[Code of Federal Regulations]
[Title 29, Volume 6]
[Revised as of July 1, 2006]
From the U.S. Government Printing Office via GPO Access
[CITE: 29CFR1910.1028]
[Page 232-250]
TITLE 29--LABOR
CHAPTER XVII--OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT
OF LABOR
PART 1910_OCCUPATIONAL SAFETY AND HEALTH STANDARDS (CONTINUED)--Table of
Contents
Subpart Z_Toxic and Hazardous Substances
Sec. 1910.1028 Benzene.
(a) Scope and application. (1) This section applies to all
occupational exposures to benzene. Chemical Abstracts Service Registry
No. 71-43-2, except as provided in paragraphs (a)(2) and (a)(3) of this
section.
(2) This section does not apply to:
(i) The storage, transportation, distribution, dispensing, sale or
use of gasoline, motor fuels, or other fuels containing benzene
subsequent to its final discharge from bulk wholesale storage
facilities, except that operations where gasoline or motor fuels are
dispensed for more than 4 hours per day in an indoor location are
covered by this section.
(ii) Loading and unloading operations at bulk wholesale storage
facilities which use vapor control systems for all loading and unloading
operations, except for the provisions of 29 CFR 1910.1200 as
incorporated into this section and the emergency provisions of
paragraphs (g) and (i)(4) of this section.
(iii) The storage, transportation, distribution or sale of benzene
or liquid mixtures containing more than 0.1 percent benzene in intact
containers or in transportation pipelines while sealed in such a manner
as to contain benzene vapors or liquid, except for the provisions of 29
CFR 1910.1200 as incorporated into this section and the emergency
provisions of paragraphs (g) and (i)(4) of this section.
(iv) Containers and pipelines carrying mixtures with less than 0.1
percent benzene and natural gas processing plants processing gas with
less than 0.1 percent benzene.
[[Page 233]]
(v) Work operations where the only exposure to benzene is from
liquid mixtures containing 0.5 percent or less of benzene by volume, or
the vapors released from such liquids until September 12, 1988; work
operations where the only exposure to benzene is from liquid mixtures
containing 0.3 percent or less of benzene by volume or the vapors
released from such liquids from September 12, 1988, to September 12,
1989; and work operations where the only exposure to benzene is from
liquid mixtures containing 0.1 percent or less of benzene by volume or
the vapors released from such liquids after September 12, 1989; except
that tire building machine operators using solvents with more than 0.1
percent benzene are covered by paragraph (i) of this section.
(vi) Oil and gas drilling, production and servicing operations.
(vii) Coke oven batteries.
(3) The cleaning and repair of barges and tankers which have
contained benzene are excluded from paragraph (f) methods of compliance,
paragraph (e)(1) exposure monitoring-general, and paragraph (e)(6)
accuracy of monitoring. Engineering and work practice controls shall be
used to keep exposures below 10 ppm unless it is proven to be not
feasible.
(b) Definitions. Action level means an airborne concentration of
benzene of 0.5 ppm calculated as an 8-hour time-weighted average.
Assistant Secretary means the Assistant Secretary of Labor for
Occupational Safety and Health, U.S. Department of Labor, or designee.
Authorized person means any person specifically authorized by the
employer whose duties require the person to enter a regulated area, or
any person entering such an area as a designated representative of
employees for the purpose of exercising the right to observe monitoring
and measuring procedures under paragraph (l) of this section, or any
other person authorized by the Act or regulations issued under the Act.
Benzene (C6 H6) (CAS Registry No. 71-43-2)
means liquefied or gaseous benzene. It includes benzene contained in
liquid mixtures and the benzene vapors released by these liquids. It
does not include trace amounts of unreacted benzene contained in solid
materials.
Bulk wholesale storage facility means a bulk terminal or bulk plant
where fuel is stored prior to its delivery to wholesale customers.
Container means any barrel, bottle, can, cylinder, drum, reaction
vessel, storage tank, or the like, but does not include piping systems.
Day means any part of a calendar day.
Director means the Director of the National Institute for
Occupational Safety and Health, U.S. Department of Health and Human
Services, or designee.
Emergency means any occurrence such as, but not limited to,
equipment failure, rupture of containers, or failure of control
equipment which may or does result in an unexpected significant release
of benzene.
Employee exposure means exposure to airborne benzene which would
occur if the employee were not using respiratory protective equipment.
Regulated area means any area where airborne concentrations of
benzene exceed or can reasonably be expected to exceed, the permissible
exposure limits, either the 8-hour time weighted average exposure of 1
ppm or the short-term exposure limit of 5 ppm for 15 minutes.
Vapor control system means any equipment used for containing the
total vapors displaced during the loading of gasoline, motor fuel or
other fuel tank trucks and the displacing of these vapors through a
vapor processing system or balancing the vapor with the storage tank.
This equipment also includes systems containing the vapors displaced
from the storage tank during the unloading of the tank truck which
balance the vapors back to the tank truck.
(c) Permissible exposure limits (PELs)--(1) Time-weighted average
limit (TWA). The employer shall assure that no employee is exposed to an
airborne concentration of benzene in excess of one part of benzene per
million parts of air (1 ppm) as an 8-hour time-weighted average.
[[Page 234]]
(2) Short-term exposure limit (STEL). The employer shall assure that
no employee is exposed to an airborne concentration of benzene in excess
of five (5) ppm as averaged over any 15 minute period.
(d) Regulated areas. (1) The employer shall establish a regulated
area wherever the airborne concentration of benzene exceeds or can
reasonably be expected to exceed the permissible exposure limits, either
the 8-hour time weighted average exposure of 1 ppm or the short-term
exposure limit of 5 ppm for 15 minutes.
(2) Access to regulated areas shall be limited to authorized
persons.
(3) Regulated areas shall be determined from the rest of the
workplace in any manner that minimizes the number of employees exposed
to benzene within the regulated area.
(e) Exposure monitoring--(1) General. (i) Determinations of employee
exposure shall be made from breathing zone air samples that are
representative of each employee's average exposure to airborne benzene.
(ii) Representative 8-hour TWA employee exposures shall be
determined on the basis of one sample or samples representing the full
shift exposure for each job classification in each work area.
(iii) Determinations of compliance with the STEL shall be made from
15 minute employee breathing zone samples measured at operations where
there is reason to believe exposures are high, such as where tanks are
opened, filled, unloaded or gauged; where containers or process
equipment are opened and where benzene is used for cleaning or as a
solvent in an uncontrolled situation. The employer may use objective
data, such as measurements from brief period measuring devices, to
determine where STEL monitoring is needed.
(iv) Except for initial monitoring as required under paragraph
(e)(2) of this section, where the employer can document that one shift
will consistently have higher employee exposures for an operation, the
employer shall only be required to determine representative employee
exposure for that operation during the shift on which the highest
exposure is expected.
(2) Initial monitoring. (i) Each employer who has a place of
employment covered under paragraph (a)(1) of this section shall monitor
each of these workplaces and work operations to determine accurately the
airborne concentrations of benzene to which employees may be exposed.
(ii) The initial monitoring required under paragraph (e)(2)(i) of
this section shall be completed by 60 days after the effective date of
this standard or within 30 days of the introduction of benzene into the
workplace. Where the employer has monitored within one year prior to the
effective date of this standard and the monitoring satisfies all other
requirements of this section, the employer may rely on such earlier
monitoring results to satisfy the requirements of paragraph (e)(2)(i) of
this section.
(3) Periodic monitoring and monitoring frequency. (i) If the
monitoring required by paragraph (e)(2)(i) of this section reveals
employee exposure at or above the action level but at or below the TWA,
the employer shall repeat such monitoring for each such employee at
least every year.
(ii) If the monitoring required by paragraph (e)(2)(i) of this
section reveals employee exposure above the TWA, the employer shall
repeat such monitoring for each such employee at least every six (6)
months.
(iii) The employer may alter the monitoring schedule from every six
months to annually for any employee for whom two consecutive
measurements taken at least 7 days apart indicate that the employee
exposure has decreased to the TWA or below, but is at or above the
action level.
(iv) Monitoring for the STEL shall be repeated as necessary to
evaluate exposures of employees subject to short term exposures.
(4) Termination of monitoring. (i) If the initial monitoring
required by paragraph (e)(2)(i) of this section reveals employee
exposure to be below the action level the employer may discontinue the
monitoring for that employee, except as otherwise required by paragraph
(e)(5) of this section.
(ii) If the periodic monitoring required by paragraph (e)(3) of this
section reveals that employee exposures,
[[Page 235]]
as indicated by at least two consecutive measurements taken at least 7
days apart, are below the action level the employer may discontinue the
monitoring for that employee, except as otherwise required by paragraph
(e)(5).
(5) Additional monitoring. (i) The employer shall institute the
exposure monitoring required under paragraphs (e)(2) and (e)(3) of this
section when there has been a change in the production, process, control
equipment, personnel or work practices which may result in new or
additional exposures to benzene, or when the employer has any reason to
suspect a change which may result in new or additional exposures.
(ii) Whenever spills, leaks, ruptures or other breakdowns occur that
may lead to employee exposure, the employer shall monitor (using area or
personal sampling) after the cleanup of the spill or repair of the leak,
rupture or other breakdown to ensure that exposures have returned to the
level that existed prior to the incident.
(6) Accuracy of monitoring. Monitoring shall be accurate, to a
confidence level of 95 percent, to within plus or minus 25 percent for
airborne concentrations of benzene.
(7) Employee notification of monitoring results. (i) The employer
must, within 15 working days after the receipt of the results of any
monitoring performed under this section, notify each affected employee
of these results either individually in writing or by posting the
results in an appropriate location that is accessible to employees.
(ii) Whenever the PELs are exceeded, the written notification
required by paragraph (e)(7)(i) of this section shall contain the
corrective action being taken by the employer to reduce the employee
exposure to or below the PEL, or shall refer to a document available to
the employee which states the corrective actions to be taken.
(f) Methods of compliance--(1) Engineering controls and work
practices. (i) The employer shall institute engineering controls and
work practices to reduce and maintain employee exposure to benzene at or
below the permissible exposure limits, except to the extent that the
employer can establish that these controls are not feasible or where the
provisions of paragraph (f)(1)(iii) or (g)(1) of this section apply.
(ii) Wherever the feasible engineering controls and work practices
which can be instituted are not sufficient to reduce employee exposure
to or below the PELs, the employer shall use them to reduce employee
exposure to the lowest levels achievable by these controls and shall
supplement them by the use of respiratory protection which complies with
the requirements of paragraph (g) of this section.
(iii) Where the employer can document that benzene is used in a
workplace less than a total of 30 days per year, the employer shall use
engineering controls, work practice controls or respiratory protection
or any combination of these controls to reduce employee exposure to
benzene to or below the PELs, except that employers shall use
engineering and work practice controls, if feasible, to reduce exposure
to or below 10 ppm as an 8-hour TWA.
(2) Compliance program. (i) When any exposures are over the PEL, the
employer shall establish and implement a written program to reduce
employee exposure to or below the PEL primarily by means of engineering
and work practice controls, as required by paragraph (f)(1) of this
section.
(ii) The written program shall include a schedule for development
and implementation of the engineering and work practice controls. These
plans shall be reviewed and revised as appropriate based on the most
recent exposure monitoring data, to reflect the current status of the
program.
(iii) Written compliance programs shall be furnished upon request
for examination and copying to the Assistant Secretary, the Director,
affected employees and designated employee representatives.
(g) Respiratory protection--(1) General. For employees who use
respirators required by this section, the employer must provide
respirators that comply with the requirements of this paragraph.
Respirators must be used during:
(i) Periods necessary to install or implement feasible engineering
and work-practice controls.
(ii) Work operations for which the employer establishes that
compliance
[[Page 236]]
with either the TWA or STEL through the use of engineering and work-
practice controls is not feasible; for example, some maintenance and
repair activities, vessel cleaning, or other operations for which
engineering and work-practice controls are infeasible because exposures
are intermittent and limited in duration.
(iii) Work operations for which feasible engineering and work-
practice controls are not yet sufficient, or are not required under
paragraph (f)(1)(iii) of this section, to reduce employee exposure to or
below the PELs.
(iv) Emergencies.
(2) Respirator program. (i) The employer must implement a
respiratory protection program in accordance with 29 CFR 1910.134 (b)
through (d) (except (d)(1)(iii), (d)(3)(iii)(B)(1), and (2)), and (f)
through (m).
(ii) For air-purifying respirators, the employer must replace the
air-purifying element at the expiration of its service life or at the
beginning of each shift in which such elements are used, whichever comes
first.
(iii) If NIOSH approves an air-purifying element with an end-of-
service-life indicator for benzene, such an element may be used until
the indicator shows no further useful life.
(3) Respirator selection. (i) The employer must select the
appropriate respirator from Table 1 of this section.
(ii) Any employee who cannot use a negative-pressure respirator must
be allowed to use a respirator with less breathing resistance, such as a
powered air-purifying respirator or supplied-air respirator.
Table 1--Respiratory Protection for Benzene
------------------------------------------------------------------------
Airborne concentration of
benzene or condition of use Respirator type
------------------------------------------------------------------------
(a) Less than or equal to 10 (1) Half-mask air-purifying respirator
ppm. with organic vapor cartridge.
(b) Less than or equal to 50 (1) Full facepiece respirator with
ppm. organic vapor cartridges.
(1) Full facepiece gas mask with chin
style canister. \1\
(c) Less than or equal to 100 (1) Full facepiece powered air-purifying
ppm. respirator with organic vapor canister.
\1\
(d) Less than or equal to (1) Supplied air respirator with full
1,000 ppm. facepiece in positive-pressure mode.
(e) Greater than 1,000 ppm or (1) Self-contained breathing apparatus
unknown concentration. with full facepiece in positive pressure
mode.
(2) Full facepiece positive-pressure
supplied-air respirator with auxiliary
self-contained air supply.
(f) Escape................... (1) Any organic vapor gas mask; or
(2) Any self-contained breathing
apparatus with full facepiece.
(g) Firefighting............. (1) Full facepiece self-contained
breathing apparatus in positive pressure
mode.
------------------------------------------------------------------------
\1\ Canisters must have a minimum service life of four (4) hours when
tested at 150 ppm benzene, at a flow rate of 64 LPM, 25 deg. C, and
85% relative humidity for non-powered air purifying respirators. The
flow rate shall be 115 LPM and 170 LPM respectively for tight fitting
and loose fitting powered air-purifying respirators.
(h) Protective clothing and equipment. Personal protective clothing
and equipment shall be worn where appropriate to prevent eye contact and
limit dermal exposure to liquid benzene. Protective clothing and
equipment shall be provided by the employer at no cost to the employee
and the employer shall assure its use where appropriate. Eye and face
protection shall meet the requirements of 29 CFR 1910.133.
(i) Medical surveillance--(1) General. (i) The employer shall make
available a medical surveillance program for employees who are or may be
exposed to benzene at or above the action level 30 or more days per
year; for employees who are or may be exposed to benzene at or above the
PELs 10 or more days per year; for employees who have been exposed to
more than 10 ppm of benzene for 30 or more days in a year prior to the
effective date of the standard when employed by their current employer;
and for employees involved in the tire building operations called tire
building machine operators, who use solvents containing greater than 0.1
percent benzene.
(ii) The employer shall assure that all medical examinations and
procedures are performed by or under the supervision of a licensed
physician and that all laboratory tests are conducted by an accredited
laboratory.
(iii) The employer shall assure that persons other than licensed
physicians
[[Page 237]]
who administer the pulmonary function testing required by this section
shall complete a training course in spirometry sponsored by an
appropriate governmental, academic or professional institution.
(iv) The employer shall assure that all examinations and procedures
are provided without cost to the employee and at a reasonable time and
place.
(2) Initial examination. (i) Within 60 days of the effective date of
this standard, or before the time of initial assignment, the employer
shall provide each employee covered by paragraph (i)(1)(i) of this
section with a medical examination including the following elements:
(A) A detailed occupational history which includes:
(1) Past work exposure to benzene or any other hematological toxins,
(2) A family history of blood dyscrasias including hematological
neoplasms;
(3) A history of blood dyscrasias including genetic hemoglobin
abnormalities, bleeding abnormalities, abnormal function of formed blood
elements;
(4) A history of renal or liver dysfunction;
(5) A history of medicinal drugs routinely taken;
(6) A history of previous exposure to ionizing radiation and
(7) Exposure to marrow toxins outside of the current work situation.
(B) A complete physical examination.
(C) Laboratory tests. A complete blood count including a leukocyte
count with differential, a quantitative thrombocyte count, hematocrit,
hemoglobin, erythrocyte count and erythrocyte indices (MCV, MCH, MCHC).
The results of these tests shall be reviewed by the examining physician.
(D) Additional tests as necessary in the opinion of the examining
physician, based on alterations to the components of the blood or other
signs which may be related to benzene exposure; and
(E) For all workers required to wear respirators for at least 30
days a year, the physical examination shall pay special attention to the
cardiopulmonary system and shall include a pulmonary function test.
(ii) No initial medical examination is required to satisfy the
requirements of paragraph (i)(2)(i) of this section if adequate records
show that the employee has been examined in accordance with the
procedures of paragraph (i)(2)(i) of this section within the twelve
months prior to the effective date of this standard.
(3) Periodic examinations. (i) The employer shall provide each
employee covered under paragraph (i)(1)(i) of this section with a
medical examination annually following the previous examination. These
periodic examinations shall incude at least the following elements:
(A) A brief history regarding any new exposure to potential marrow
toxins, changes in medicinal drug use, and the appearance of physical
signs relating to blood disorders:
(B) A complete blood count including a leukocyte count with
differential, quantitative thrombocyte count, hemoglobin, hematocrit,
erythrocyte count and erythrocyte indices (MCV, MCH, MCHC); and
(C) Appropriate additional tests as necessary, in the opinion of the
examining physician, in consequence of alterations in the components of
the blood or other signs which may be related to benzene exposure.
(ii) Where the employee develops signs and symptoms commonly
associated with toxic exposure to benzene, the employer shall provide
the employee with an additional medical examination which shall include
those elements considered appropriate by the examining physician.
(iii) For persons required to use respirators for at least 30 days a
year, a pulmonary function test shall be performed every three (3)
years. A specific evaluation of the cardiopulmonary system shall be made
at the time of the pulmonary function test.
(4) Emergency examinations. (i) In addition to the surveillance
required by (i)(1)(i), if an employee is exposed to benzene in an
emergency situation, the employer shall have the employee provide a
urine sample at the end of the employee's shift and have a urinary
phenol test performed on the sample within 72 hours. The urine specific
gravity shall be corrected to 1.024.
(ii) If the result of the urinary phenol test is below 75 mg phenol/
L of urine, no further testing is required.
[[Page 238]]
(iii) If the result of the urinary phenol test is equal to or
greater than 75 mg phenol/L of urine, the employer shall provide the
employee with a complete blood count including an erythrocyte count,
leukocyte count with differential and thrombocyte count at monthly
intervals for a duration of three (3) months following the emergency
exposure.
(iv) If any of the conditions specified in paragraph (i)(5)(i) of
this section exists, then the further requirements of paragraph (i)(5)
of this section shall be met and the employer shall, in addition,
provide the employees with periodic examinations if directed by the
physician.
(5) Additional examinations and referrals. (i) Where the results of
the complete blood count required for the initial and periodic
examinations indicate any of the following abnormal conditions exist,
then the blood count shall be repeated within 2 weeks.
(A) The hemoglobin level or the hematocrit falls below the normal
limit [outside the 95% confidence interval (C.I.)] as determined by the
laboratory for the particular geographic area and/or these indices show
a persistent downward trend from the individual's pre-exposure norms;
provided these findings cannot be explained by other medical reasons.
(B) The thrombocyte (platelet) count varies more than 20 percent
below the employee's most recent values or falls outside the normal
limit (95% C.I.) as determined by the laboratory.
(C) The leukocyte count is below 4,000 per mm\3\ or there is an
abnormal differential count.
(ii) If the abnormality persists, the examining physician shall
refer the employee to a hematologist or an internist for further
evaluation unless the physician has good reason to believe such referral
is unnecessary. (See Appendix C for examples of conditions where a
referral may be unnecessary.)
(iii) The employer shall provide the hematologist or internist with
the information required to be provided to the physician under paragraph
(i)(6) of this section and the medical record required to be maintained
by paragraph (k)(2)(ii) of this section.
(iv) The hematologist's or internist's evaluation shall include a
determination as to the need for additional tests, and the employer
shall assure that these tests are provided.
(6) Information provided to the physician. The employer shall
provide the following information to the examining physician:
(i) A copy of this regulation and its appendices;
(ii) A description of the affected employee's duties as they relate
to the employee's exposure;
(iii) The employee's actual or representative exposure level:
(iv) A description of any personal protective equipment used or to
be used; and
(v) Information from previous employment-related medical
examinations of the affected employee which is not otherwise available
to the examining physician.
(7) Physician's written opinions. (i) For each examination under
this section, the employer shall obtain and provide the employee with a
copy of the examining physician's written opinion within 15 days of the
examination. The written opinion shall be limited to the following
information:
(A) The occupationally pertinent results of the medical examination
and tests;
(B) The physician's opinion concerning whether the employee has any
detected medical conditions which would place the employee's health at
greater than normal risk of material impairment from exposure to
benzene;
(C) The physician's recommended limitations upon the employee's
exposure to benzene or upon the employee's use of protective clothing or
equipment and respirators.
(D) A statement that the employee has been informed by the physician
of the results of the medical examination and any medical conditions
resulting from benzene exposure which require further explanation or
treatment.
(ii) The written opinion obtained by the employer shall not reveal
specific records, findings and diagnoses that have no bearing on the
employee's ability to work in a benzene-exposed workplace.
[[Page 239]]
(8) Medical removal plan. (i) When a physician makes a referral to a
hematologist/internist as required under paragraph (i)(5)(ii) of this
section, the employee shall be removed from areas where exposures may
exceed the action level until such time as the physician makes a
determination under paragraph (i)(8)(ii) of this section.
(ii) Following the examination and evaluation by the hematologist/
internist, a decision to remove an employee from areas where benzene
exposure is above the action level or to allow the employee to return to
areas where benzene exposure is above the action level shall be made by
the physician in consultation with the hematologist/internist. This
decision shall be communicated in writing to the employer and employee.
In the case of removal, the physician shall state the required probable
duration of removal from occupational exposure to benzene above the
action level and the requirements for future medical examinations to
review the decision.
(iii) For any employee who is removed pursuant to paragraph
(i)(8)(ii) of this section, the employer shall provide a follow-up
examination. The physician, in consultation with the hematologist/
internist, shall make a decision within 6 months of the date the
employee was removed as to whether the employee shall be returned to the
usual job or whether the employee should be removed permanently.
(iv) Whenever an employee is temporarily removed from benzene
exposure pursuant to paragraph (i)(8)(i) or (i)(8)(ii) of this section,
the employer shall transfer the employee to a comparable job for which
the employee is qualified (or can be trained for in a short period) and
where benzene exposures are as low as possible, but in no event higher
than the action level. The employer shall maintain the employee's
current wage rate, seniority and other benefits. If there is no such job
available, the employer shall provide medical removal protection
benefits until such a job becomes available or for 6 months, whichever
comes first.
(v) Whenever an employee is removed permanently from benzene
exposure based on a physician's recommendation pursuant to paragraph
(i)(8)(iii) of this section, the employee shall be given the opportunity
to transfer to another position which is available or later becomes
available for which the employee is qualified (or can be trained for in
a short period) and where benzene exposures are as low as possible but
in no event higher than the action level. The employer shall assure that
such employee suffers no reduction in current wage rate, seniority or
other benefits as a result of the transfer.
(9) Medical removal protection benefits. (i) The employer shall
provide to an employee 6 months of medical removal protection benefits
immediately following each occasion an employee is removed from exposure
to benzene because of hematological findings pursuant to paragraphs
(i)(8) (i) and (ii) of this section, unless the employee has been
transferred to a comparable job where benzene exposures are below the
action level.
(ii) For the purposes of this section, the requirement that an
employer provide medical removal protection benefits means that the
employer shall maintain the current wage rate, seniority and other
benefits of an employee as though the employee had not been removed.
(iii) The employer's obligation to provide medical removal
protection benefits to a removed employee shall be reduced to the extent
that the employee receives compensation for earnings lost during the
period of removal either from a publicly or employer-funded compensation
program, or from employment with another employer made possible by
virtue of the employee's removal.
(j) Communication of benzene hazards to employees--(1) Signs and
labels. (i) The employer shall post signs at entrances to regulated
areas. The signs shall bear the following legend:
DANGER
BENZENE
CANCER HAZARD
FLAMMABLE--NO SMOKING
AUTHORIZED PERSONNEL ONLY
RESPIRATOR REQUIRED
(ii) The employer shall ensure that lables or other appropriate
forms of warning are provided for containers of benzene within the
workplace. There is
[[Page 240]]
no requirement to label pipes. The labels shall comply with the
requirements of 29 CFR 1910.1200(f) and in addition shall include the
following legend:
DANGER
CONTAINS BENZENE
CANCER HAZARD
(2) Material safety data sheets. (i) Employers shall obtain or
develop, and shall provide access to their employees, to a material
safety data sheet (MSDS) which addresses benzene and complies with 29
CFR 1910.1200.
(ii) Employers who are manufacturers or importers shall:
(A) Comply with paragraph (a) of this section, and
(B) Comply with the requirement in OSHA's Hazard Communication
Standard, 29 CFR 1910.1200, that they deliver to downstream employers an
MSDS which addresses benzene.
(3) Information and training. (i) The employer shall provide
employees with information and training at the time of their initial
assignment to a work area where benzene is present. If exposures are
above the action level, employees shall be provided with information and
training at least annually thereafter.
(ii) The training program shall be in accordance with the
requirements of 29 CFR 1910.1200(h) (1) and (2), and shall include
specific information on benzene for each category of information
included in that section.
(iii) In addition to the information required under 29 CFR
1910.1200, the employer shall:
(A) Provide employees with an explanation of the contents of this
section, including Appendices A and B, and indicate to them where the
standard is available; and
(B) Describe the medical surveillance program required under
paragraph (i) of this section, and explain the information contained in
Appendix C.
(k) Recordkeeping--(1) Exposure measurements. (i) The employer shall
establish and maintain an accurate record of all measurements required
by paragraph (e) of this section, in accordance with 29 CFR 1910.20.
(ii) This record shall include:
(A) The dates, number, duration, and results of each of the samples
taken, including a description of the procedure used to determine
representative employee exposures;
(B) A description of the sampling and analytical methods used;
(C) A description of the type of respiratory protective devices
worn, if any; and
(D) The name, social security number, job classification and
exposure levels of the employee monitored and all other employees whose
exposure the measurement is intended to represent.
(iii) The employer shall maintain this record for at least 30 years,
in accordance with 29 CFR 1910.20.
(2) Medical surveillance. (i) The employer shall establish and
maintain an accurate record for each employee subject to medical
surveillance required by paragraph (i) of this section, in accordance
with 29 CFR 1910.20.
(ii) This record shall include:
(A) The name and social security number of the employee;
(B) The employer's copy of the physician's written opinion on the
initial, periodic and special examinations, including results of medical
examinations and all tests, opinions and recommendations;
(C) Any employee medical complaints related to exposure to benzene;
(D) A copy of the information provided to the physician as required
by paragraphs (i)(6) (ii) through (v) of this section; and
(E) A copy of the employee's medical and work history related to
exposure to benzene or any other hematologic toxins.
(iii) The employer shall maintain this record for at least the
duration of employment plus 30 years, in accordance with 29 CFR 1910.20.
(3) Availability. (i) The employer shall assure that all records
required to be maintained by this section shall be made available upon
request to the Assistant Secretary and the Director for examination and
copying.
(ii) Employee exposure monitoring records required by this paragraph
shall be provided upon request for examination and copying to employees,
employee representatives, and the Assistant Secretary in accordance with
29 CFR 1910.20 (a) through (e) and (g) through (i).
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(iii) Employee medical records required by this paragraph shall be
provided upon request for examination and copying, to the subject
employee, to anyone having the specific written consent of the subject
employee, and to the Assistant Secretary in accordance with 29 CFR
1910.20.
(4) Transfer of records. (i) The employer shall comply with the
requirements involving transfer of records set forth in 29 CFR
1019.20(h).
(ii) If the employer ceases to do business and there is no successor
employer to receive and retain the records for the prescribed period,
the employer shall notify the Director, at least three (3) months prior
to disposal, and transmit them to the Director if required by the
Director within that period.
(l) Observation of monitoring--(1) Employee observation. The
employer shall provide affected employees, or their designated
representatives, an opportunity to observe the measuring or monitoring
of employee exposure to benzene conducted pursuant to paragraph (e) of
this section.
(2) Observation procedures. When observation of the measuring or
monitoring of employee exposure to benzene requires entry into areas
where the use of protective clothing and equipment or respirators is
required, the employer shall provide the observer with personal
protective clothing and equipment or respirators required to be worn by
employees working in the area, assure the use of such clothing and
equipment or respirators, and require the observer to comply with all
other applicable safety and health procedures.
(m) [Reserved]
(n) Appendices. The information contained in Appendices A, B, C, and
D is not intended, by itself, to create any additional obligations not
otherwise imposed or to detract from any existing obligations.
Appendix A to Sec. 1910.1028--Substance Safety Data Sheet, Benzene
I. Substance Identification
A. Substance: Benzene.
B. Permissible Exposure: Except as to the use of gasoline, motor
fuels and other fuels subsequent to discharge from bulk terminals and
other exemptions specified in Sec. 1910.1028(a)(2):
1. Airborne: The maximum time-weighted average (TWA) exposure limit
is 1 part of benzene vapor per million parts of air (1 ppm) for an 8-
hour workday and the maximum short-term exposure limit (STEL) is 5 ppm
for any 15-minute period.
2. Dermal: Eye contact shall be prevented and skin contact with
liquid benzene shall be limited.
C. Appearance and odor: Benzene is a clear, colorless liquid with a
pleasant, sweet odor. The odor of benzene does not provide adequate
warning of its hazard.
II. Health Hazard Data
A. Ways in which benzene affects your health. Benzene can affect
your health if you inhale it, or if it comes in contact with your skin
or eyes. Benzene is also harmful if you happen to swallow it.
B. Effects of overexposure. 1. Short-term (acute) overexposure: If
you are overexposed to high concentrations of benzene, well above the
levels where its odor is first recognizable, you may feel breathless,
irritable, euphoric, or giddy; you may experience irritation in eyes,
nose, and respiratory tract. You may develop a headache, feel dizzy,
nauseated, or intoxicated. Severe exposures may lead to convulsions and
loss of consciousness.
2. Long-term (chronic) exposure. Repeated or prolonged exposure to
benzene, even at relatively low concentrations, may result in various
blood disorders, ranging from anemia to leukemia, an irreversible, fatal
disease. Many blood disorders associated with benzene exposure may occur
without symptoms.
III. Protective Clothing and Equipment
A. Respirators. Respirators are required for those operations in
which engineering controls or work practice controls are not feasible to
reduce exposure to the permissible level. However, where employers can
document that benzene is present in the workplace less than 30 days a
year, respirators may be used in lieu of engineering controls. If
respirators are worn, they must have joint Mine Safety and Health
Administration and the National Institute for Occupational Safety and
Health (NIOSH) seal of approval, and cartridge or canisters must be
replaced before the end of their service life, or the end of the shift,
whichever occurs first. If you experience difficulty breathing while
wearing a respirator, you may request a positive pressure respirator
from your employer. You must be thoroughly trained to use the assigned
respirator, and the training will be provided by your employer.
B. Protective Clothing. You must wear appropriate protective
clothing (such as boots, gloves, sleeves, aprons, etc.) over any parts
of your body that could be exposed to liquid benzene.
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C. Eye and Face Protection. You must wear splash-proof safety
goggles if it is possible that benzene may get into your eyes. In
addition, you must wear a face shield if your face could be splashed
with benzene liquid.
IV. Emergency and First Aid Procedures
A. Eye and face exposure. If benzene is splashed in your eyes, wash
it out immediately with large amounts of water. If irritation persists
or vision appears to be affected see a doctor as soon as possible.
B. Skin exposure. If benzene is spilled on your clothing or skin,
remove the contaminated clothing and wash the exposed skin with large
amounts of water and soap immediately. Wash contaminated clothing before
you wear it again.
C. Breathing. If you or any other person breathes in large amounts
of benzene, get the exposed person to fresh air at once. Apply
artificial respiration if breathing has stopped. Call for medical
assistance or a doctor as soon as possible. Never enter any vessel or
confined space where the benzene concentration might be high without
proper safety equipment and at least one other person present who will
stay outside. A life line should be used.
D. Swallowing. If benzene has been swallowed and the patient is
conscious, do not induce vomiting. Call for medical assistance or a
doctor immediately.
V. Medical Requirements
If you are exposed to benzene at a concentration at or above 0.5 ppm
as an 8-hour time-weighted average, or have been exposed at or above 10
ppm in the past while employed by your current employer, your employer
is required to provide a medical examination and history and laboratory
tests within 60 days of the effective date of this standard and annually
thereafter. These tests shall be provided without cost to you. In
addition, if you are accidentally exposed to benzene (either by
ingestion, inhalation, or skin/eye contact) under emergency conditions
known or suspected to constitute toxic exposure to benzene, your
employer is required to make special laboratory tests available to you.
VI. Observation of Monitoring
Your employer is required to perform measurements that are
representative of your exposure to benzene and you or your designated
representative are entitled to observe the monitoring procedure. You are
entitled to observe the steps taken in the measurement procedure, and to
record the results obtained. When the monitoring procedure is taking
place in an area where respirators or personal protective clothing and
equipment are required to be worn, you or your representative must also
be provided with, and must wear the protective clothing and equipment.
VII. Access to Records
You or your representative are entitled to see the records of
measurements of your exposure to benzene upon written request to your
employer. Your medical examination records can be furnished to yourself,
your physician or designated representative upon request by you to your
employer.
VIII. Precautions for Safe Use, Handling and Storage
Benzene liquid is highly flammable. It should be stored in tightly
closed containers in a cool, well ventilated area. Benzene vapor may
form explosive mixtures in air. All sources of ignition must be
controlled. Use nonsparking tools when opening or closing benzene
containers. Fire extinguishers, where provided, must be readily
available. Know where they are located and how to operate them. Smoking
is prohibited in areas where benzene is used or stored. Ask your
supervisor where benzene is used in your area and for additional plant
safety rules.
Appendix B to Sec. 1910.1028--Substance Technical Guidelines, Benzene
I. Physical and Chemical Data
A. Substance identification.
1. Synonyms: Benzol, benzole, coal naphtha, cyclohexatriene, phene,
phenyl hydride, pyrobenzol. (Benzin, petroleum benzin and Benzine do not
contain benzene).
2. Formula: C6 H6 (CAS Registry Number: 71-43-
2)
B. Physical data.
1. Boiling Point (760 mm Hg); 80.1 [deg]C (176 [deg]F)
2. Specific Gravity (water=1): 0.879
3. Vapor Density (air=1): 2.7
4. Melting Point: 5.5 [deg]C (42 [deg]F)
5. Vapor Pressure at 20 [deg]C (68 [deg]F): 75 mm Hg
6. Solubility in Water: .06%
7. Evaporation Rate (ether=1): 2.8
8. Appearance and Odor: Clear, colorless liquid with a distinctive
sweet odor.
II. Fire, Explosion, and Reactivity Hazard Data
A. Fire.
1. Flash Point (closed cup): -11 [deg]C (12 [deg]F)
2. Autoignition Temperature: 580 [deg]C (1076 [deg]F)
3. Flammable limits in Air. % by Volume: Lower: 1.3%, Upper: 7.5%
4. Extinguishing Media: Carbon dioxide, dry chemical, or foam.
5. Special Fire-Fighting procedures: Do not use solid stream of
water, since stream will scatter and spread fire. Fine water spray can
be used to keep fire-exposed containers cool.
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6. Unusual fire and explosion hazards: Benzene is a flammable
liquid. Its vapors can form explosive mixtures. All ignition sources
must be controlled when benzene is used, handled, or stored. Where
liquid or vapor may be released, such areas shall be considered as
hazardous locations. Benzene vapors are heavier than air; thus the
vapors may travel along the ground and be ignited by open flames or
sparks at locations remote from the site at which benzene is handled.
7. Benzene is classified as a 1 B flammable liquid for the purpose
of conforming to the requirements of 29 CFR 1910.106. A concentration
exceeding 3,250 ppm is considered a potential fire explosion hazard.
Locations where benzene may be present in quantities sufficient to
produce explosive or ignitable mixtures are considered Class I Group D
for the purposes of conforming to the requirements of 29 CFR 1910.309.
B. Reactivity.
1. Conditions contributing to instability: Heat.
2. Incompatibility: Heat and oxidizing materials.
3. Hazardous decomposition products: Toxic gases and vapors (such as
carbon monoxide).
III. Spill and Leak Procedures
A. Steps to be taken if the material is released or spilled. As much
benzene as possible should be absorbed with suitable materials, such as
dry sand or earth. That remaining must be flushed with large amounts of
water. Do not flush benzene into a confined space, such as a sewer,
because of explosion danger. Remove all ignition sources. Ventilate
enclosed places.
B. Waste disposal method. Disposal methods must conform to other
jurisdictional regulations. If allowed, benzene may be disposed of: (a)
By absorbing it in dry sand or earth and disposing in a sanitary
landfill; (b) if small quantities, by removing it to a safe location
from buildings or other combustible sources, pouring it in dry sand or
earth and cautiously igniting it; and (c) if large quantities, by
atomizing it in a suitable combustion chamber.
IV. Miscellaneous Precautions
A. High exposure to benzene can occur when transferring the liquid
from one container to another. Such operations should be well ventilated
and good work practices must be established to avoid spills.
B. Use non-sparking tools to open benzene containers which are
effectively grounded and bonded prior to opening and pouring.
C. Employers must advise employees of all plant areas and operations
where exposure to benzene could occur. Common operations in which high
exposures to benzene may be encountered are: the primary production and
utilization of benzene, and transfer of benzene.
Appendix C to Sec. 1910.1028--Medical Surveillance Guidelines for
Benzene
I. Route of Entry
Inhalation; skin absorption.
II. Toxicology
Benzene is primarily an inhalation hazard. Systemic absorption may
cause depression of the hematopoietic system, pancytopenia, aplastic
anemia, and leukemia. Inhalation of high concentrations can affect
central nervous system function. Aspiration of small amounts of liquid
benzene immediately causes pulmonary edema and hemorrhage of pulmonary
tissue. There is some absorption through the skin. Absorption may be
more rapid in the case of abraded skin, and benzene may be more readily
absorbed if it is present in a mixture or as a contaminant in solvents
which are readily absorbed. The defatting action of benzene may produce
primary irritation due to repeated or prolonged contact with the skin.
High concentration are irritating to the eyes and the mucuous membranes
of the nose, and respiratory tract.
III. Signs and Symptoms
Direct skin contact with benzene may cause erythema. Repeated or
prolonged contact may result in drying, scaling dermatitis, or
development of secondary skin infections. In addition, there is benzene
absorption through the skin. Local effects of benzene vapor or liquid on
the eye are slight. Only at very high concentrations is there any
smarting sensation in the eye. Inhalation of high concentrations of
benzene may have an initial stimulatory effect on the central nervous
system characterized by exhilaration, nervous excitation, and/or
giddiness, followed by a period of depression, drowsiness, or fatigue. A
sensation of tightness in the chest accompanied by breathlessness may
occur and ultimately the victim may lose consciousness. Tremors,
convulsions and death may follow from respiratory paralysis or
circulatory collapse in a few minutes to several hours following severe
exposures.
The detrimental effect on the blood-forming system of prolonged
exposure to small quantities of benzene vapor is of extreme importance.
The hematopoietic system is the chief target for benzene's toxic effects
which are manifested by alterations in the levels of formed elements in
the peripheral blood. These effects have occurred at concentrations of
benzene which may not cause irritation of mucous membranes, or any
unpleasant sensory effects. Early signs and symptoms of benzene
morbidity are varied, often
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not readily noticed and non-specific. Subjective complaints of headache,
dizziness, and loss of appetite may precede or follow clinical signs.
Rapid pulse and low blood pressure, in addition to a physical appearance
of anemia, may accompany a subjective complaint of shortness of breath
and excessive tiredness. Bleeding from the nose, gums, or mucous
membranes, and the development of purpuric spots (small bruises) may
occur as the condition progresses. Clinical evidence of leukopenia,
anemia, and thrombocytopenia, singly or in combination, has been
frequently reported among the first signs.
Bone marrow may appear normal, aplastic, or hyperplastic, and may
not, in all situations, correlate with peripheral blood forming tissues.
Because of variations in the susceptibility to benzene morbidity, there
is no ``typical'' blood picture. The onset of effects of prolonged
benzene exposure may be delayed for many months or years after the
actual exposure has ceased and identification or correlation with
benzene exposure must be sought out in the occupational history.
IV. Treatment of Acute Toxic Effects
Remove from exposure immediately. Make sure you are adequately
protected and do not risk being overcome by fumes. Give oxygen or
artificial resuscitation if indicated. Flush eyes, wash skin if
contaminated and remove all contaminated clothing. Symptoms of
intoxication may persist following severe exposures. Recovery from mild
exposures is usually rapid and complete.
V. Surveillance and Preventive Considerations
A. General
The principal effects of benzene exposure which form the basis for
this regulation are pathological changes in the hematopoietic system,
reflected by changes in the peripheral blood and manifesting clinically
as pancytopenia, aplastic anemia, and leukemia. Consequently, the
medical surveillance program is designed to observe, on a regular basis,
blood indices for early signs of these effects, and although early signs
of leukemia are not usually available, emerging diagnostic technology
and innovative regimes make consistent surveillance for leukemia, as
well as other hematopoietic effects, essential.
Initial examinations are to be provided within 60 days of the
effective date of this standard, or at the time of initial assignment,
and periodic examinations annually thereafter. There are special
provisions for medical tests in the event of hematologic abnormalities
or for emergency situations.
The blood values which require referral to a hematologist or
internist are noted in the standard in paragraph (i)(5). The standard
specifies that blood abnormalities that persist must be referred
``unless the physician has good reason to believe such referral is
unnecessary'' (paragraph (i)(5)). Examples of conditions that could make
a referral unnecessary despite abnormal blood limits are iron or folate
deficiency, menorrhagia, or blood loss due to some unrelated medical
abnormality.
Symptoms and signs of benzene toxicity can be non-specific. Only a
detailed history and appropriate investigative procedures will enable a
physician to rule out or confirm conditions that place the employee at
increased risk. To assist the examining physician with regard to which
laboratory tests are necessary and when to refer an employee to the
specialist, OSHA has established the following guidelines.
B. Hematology Guidelines
A minimum battery of tests is to be performed by strictly
standardized methods.
1. Red cell, white cell, platelet counts, white blood cell
differential, hematacrit and red cell indices must be performed by an
accredited laboratory. The normal ranges for the red cell and white cell
counts are influenced by altitude, race, and sex, and therefore should
be determined by the accredited laboratory in the specific area where
the tests are performed.
Either a decline from an absolute normal or an individual's base
line to a subnormal value or a rise to a supra-normal value, are
indicative of potential toxicity, particularly if all blood parameters
decline. The normal total white blood count is approximately 7,200/mm\3\
plus or minus 3,000. For cigarette smokers the white count may be higher
and the upper range may be 2,000 cells higher than normal for the
laboratory. In addition, infection, allergies and some drugs may raise
the white cell count. The normal platelet count is approximately 250,000
with a range of 140,000 to 400,000. Counts outside this range should be
regarded as possible evidence of benzene toxicity.
Certain abnormalities found through routine screening are of greater
significance in the benzene-exposed worker and require prompt
consultation with a specialist, namely:
a. Thrombocytopenia.
b. A trend of decreasing white cell, red cell, or platelet indices
in an individual over time is more worrisome than an isolated abnormal
finding at one test time. The importance of trend highlights the need to
compare an individual's test results to baseline and/or previous
periodic tests.
c. A constellation or pattern of abnormalities in the different
blood indices is of more significance than a single abnormality. A low
white count not associated with any abnormalities in other cell indices
may be a normal statistical variation, whereas if the low white count is
accompanied by decreases
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in the platelet and/or red cell indices, such a pattern is more likely
to be associated with benzene toxicity and merits thorough
investigation.
Anemia, leukopenia, macrocytosis or an abnormal differential white
blood cell count should alert the physician to further investigate and/
or refer the patient if repeat tests confirm the abnormalities. If
routine screening detects an abnormality, follow-up tests which may be
helpful in establishing the etiology of the abnormality are the
peripheral blood smear and the reticulocyte count.
The extreme range of normal for reticulocytes is 0.4 to 2.5 percent
of the red cells, the usual range being 0.5 to 1.2 percent of the red
cells, but the typical value is in the range of 0.8 to 1.0 percent. A
decline in reticulocytes to levels of less than 0.4 percent is to be
regarded as possible evidence (unless another specific cause is found)
of benzene toxicity requiring accelerated surveillance. An increase in
reticulocyte levels to about 2.5 percent may also be consistent with
(but is not as characteristic of) benzene toxicity.
2. An important diagnostic test is a careful examination of the
peripheral blood smear. As with reticulocyte count the smear should be
with fresh uncoagulated blood obtained from a needle tip following
venipuncture or from a drop of earlobe blood (capillary blood). If
necessary, the smear may, under certain limited conditions, be made from
a blood sample anticoagulated with EDTA (but never with oxalate or
heparin). When the smear is to be prepared from a specimen of venous
blood which has been collected by a commercial Vacutainer
[reg] type tube containing neutral EDTA, the smear should be
made as soon as possible after the venesection. A delay of up to 12
hours is permissible between the drawing of the blood specimen into EDTA
and the preparation of the smear if the blood is stored at refrigerator
(not freezing) temperature.
3. The minimum mandatory observations to be made from the smear are:
a. The differential white blood cell count.
b. Description of abnormalities in the appearance of red cells.
c. Description of any abnormalities in the platelets.
d. A careful search must be made throughout of every blood smear for
immature white cells such as band forms (in more than normal proportion,
i.e., over 10 percent of the total differential count), any number of
metamyelocytes, myelocytes or myeloblasts. Any nucleate or
multinucleated red blood cells should be reported. Large ``giant''
platelets or fragments of megakaryocytes must be recognized.
An increase in the proportion of band forms among the neutrophilic
granulocytes is an abnormality deserving special mention, for it may
represent a change which should be considered as an early warning of
benzene toxicity in the absence of other causative factors (most
commonly infection). Likewise, the appearance of metamyelocytes, in the
absence of another probable cause, is to be considered a possible
indication of benzene-induced toxicity.
An upward trend in the number of basophils, which normally do not
exceed about 2.0 percent of the total white cells, is to be regarded as
possible evidence of benzene toxicity. A rise in the eosinophil count is
less specific but also may be suspicious of toxicity if the rises above
6.0 percent of the total white count.
The normal range of monocytes is from 2.0 to 8.0 percent of the
total white count with an average of about 5.0 percent. About 20 percent
of individuals reported to have mild but persisting abnormalities caused
by exposure to benzene show a persistent monocytosis. The findings of a
monocyte count which persists at more than 10 to 12 percent of the
normal white cell count (when the total count is normal) or persistence
of an absolute monocyte count in excess of 800/mm\3\ should be regarded
as a possible sign of benzene-induced toxicity.
A less frequent but more serious indication of benzene toxicity is
the finding in the peripheral blood of the so-called ``pseudo'' (or
acquired) Pelger-Huet anomaly. In this anomaly many, or sometimes the
majority, of the neutrophilic granulocytes possess two round nuclear
segements--less often one or three round segments--rather than three
normally elongated segments. When this anomaly is not hereditary, it is
often but not invariably predictive of subsequent leukemia. However,
only about two percent of patients who ultimately develop acute
myelogenous leukemia show the acquired Pelger-Huet anomaly. Other tests
that can be administered to investigate blood abnormalities are
discussed below; however, such procedures should be undertaken by the
hematologist.
An uncommon sign, which cannot be detected from the smear, but can
be elicited by a ``sucrose water test'' of peripheral blood, is
transient paroxysmal nocturnal hemoglobinuria (PNH), which may first
occur insidiously during a period of established aplastic anemia, and
may be followed within one to a few years by the appearance of rapidly
fatal acute myelogenous leukemia. Clinical detection of PNH, which
occurs in only one or two percent of those destined to have acute
myelogenous leukemia, may be difficult; if the ``sucrose water test'' is
positive, the somewhat more definitive Ham test, also known as the acid-
serum hemolysis test, may provide confirmation.
e. Individuals documented to have developed acute myelogenous
leukemia years after initial exposure to benzene may have progressed
through a preliminary phase of
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hematologic abnormality. In some instances pancytopenia (i.e., a
lowering in the counts of all circulating blood cells of bone marrow
origin, but not to the extent implied by the term ``aplastic anemia'')
preceded leukemia for many years. Depression of a single blood cell type
or platelets may represent a harbinger of aplasia or leukemia. The
finding of two or more cytopenias, or pancytopenia in a benzene-exposed
individual, must be regarded as highly suspicious of more advanced
although still reversible, toxicity. ``Pancytopenia'' coupled with the
appearance of immature cells (myelocytes, myeloblasts, erythroblasts,
etc.), with abnormal cells (pseudo Pelger-Huet anomaly, atypical nuclear
heterochromatin, etc.), or unexplained elevations of white blood cells
must be regarded as evidence of benzene overexposure unless proved
otherwise. Many severely aplastic patients manifested the ominous
finding of 5-10 percent myeloblasts in the marrow, occasional
myeloblasts and myelocytes in the blood and 20-30% monocytes. It is
evident that isolated cytopenias, pancytopenias, and even aplastic
anemias induced by benzene may be reversible and complete recovery has
been reported on cessation of exposure. However, since any of these
abnormalities is serious, the employee must immediately be removed from
any possible exposure to benzene vapor. Certain tests may substantiate
the employee's prospects for progression or regression. One such test
would be an examination of the bone marrow, but the decision to perform
a bone marrow aspiration or needle biopsy is made by the hematologist.
The findings of basophilic stippling in circulating red blood cells
(usually found in 1 to 5% of red cells following marrow injury), and
detection in the bone marrow of what are termed ``ringed sideroblasts''
must be taken seriously, as they have been noted in recent years to be
premonitory signs of subsequent leukemia.
Recently peroxidase-staining of circulating or marrow neutrophil
granulocytes, employing benzidine dihydrochloride, have revealed the
disappearance of, or diminution in, peroxidase in a sizable proportion
of the granulocytes, and this has been reported as an early sign of
leukemia. However, relatively few patients have been studied to date.
Granulocyte granules are normally strongly peroxidase positive. A steady
decline in leukocyte alkaline phosphatase has also been reported as
suggestive of early acute leukemia. Exposure to benzene may cause an
early rise in serum iron, often but not always associated with a fall in
the reticulocyte count. Thus, serial measurements of serum iron levels
may provide a means of determining whether or not there is a trend
representing sustained suppression of erythropoiesis.
Measurement of serum iron, determination of peroxidase and of
alkaline phosphatase activity in peripheral granulocytes can be
performed in most pathology laboratories. Peroxidase and alkaline
phosphatase staining are usually undertaken when the index of suspecion
for leukemia is high.
Appendix D to Sec. 1910.1028--Sampling and Analytical Methods for
Benzene Monitoring and Measurement Procedures
Measurements taken for the purpose of determining employee exposure
to benzene are best taken so that the representative average 8-hour
exposure may be determined from a single 8-hour sample or two (2) 4-hour
samples. Short-time interval samples (or grab samples) may also be used
to determine average exposure level if a minimum of five measurements
are taken in a random manner over the 8-hour work shift. Random sampling
means that any portion of the work shift has the same change of being
sampled as any other. The arithmetic average of all such random samples
taken on one work shift is an estimate of an employee's average level of
exposure for that work shift. Air samples should be taken in the
employee's breathing zone (air that would most nearly represent that
inhaled by the employee). Sampling and analysis must be performed with
procedures meeting the requirements of the standard.
There are a number of methods available for monitoring employee
exposures to benzene. The sampling and analysis may be performed by
collection of the benzene vaptor or charcoal absorption tubes, with
subsequent chemical analysis by gas chromatography. Sampling and
analysis may also be performed by portable direct reading instruments,
real-time continuous monitoring systems, passive dosimeters or other
suitable methods. The employer has the obligation of selecting a
monitoring method which meets the accuracy and precision requirements of
the standard under his unique field conditions. The standard requires
that the method of monitoring must have an accuracy, to a 95 percent
confidence level, of not less than plus or minus 25 percent for
concentrations of benzene greater than or equal to 0.5 ppm.
The OSHA Laboratory modified NIOSH Method S311 and evaluated it at a
benzene air concentration of 1 ppm. A procedure for determining the
benzene concentration in bulk material samples was also evalauted. This
work, reported in OSHA Laboratory Method No. 12, includes the following
two analytical procedures:
I. OSHA Method 12 for Air Samples
Analyte: Benzene
Matrix: Air
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Procedure: Adsorption on charcoal, desorption with carbon disulfide,
analysis by GC.
Detection limit: 0.04 ppm
Recommended air volume and sampling rate: 10L to 0.2 L/min.
1. Principle of the Method.
1.1 A known volume of air is drawn through a charcoal tube to trap
the organic vapors present.
1.2. The charcoal in the tube is transferred to a small, stoppered
vial, and the anlyte is desorbed with carbon disulfide.
1.3. An aliquot of the desorbed sample is injected into a gas
chromatograph.
1.4 The area of the resulting peak is determined and compared with
areas obtained from standards.
2. Advantages and disadvantages of the method.
2.1 The sampling device is small, portable, and involved no liquids.
Interferences are minimal, and most of those which do occur can be
eliminated by altering chromatographic conditions. The samples are
analyzed by means of a quick, instrumental method.
2.2 The amount of sample which can be taken is limited by the number
of milligrams that the tube will hold before overloading. When the
sample value obtained for the backup section of the charcoal tube
exceeds 25 percent of that found on the front section, the possibility
of sample loss exists.
3. Apparatus.
3.1 A calibrated personal sampling pump whose flow can be determined
within 5 percent at the recommended flow rate.
3.2. Charcoal tubes: Glass with both ends flame sealed, 7 cm long
with a 6-mm O.D. and a 4-mm I.D., containing 2 sections of 20/40 mesh
activated charcoal separated by a 2-mm portion of urethane foam. The
activated charcoal is prepared from coconut shells and is fired at 600
[deg]C prior to packing. The adsorbing section contains 100 mg of
charcoal, the back-up section 50 mg. A 3-mm portion of urethane foam is
placed between the outlet end of the tube and the back-up section. A
plug of silanized glass wool is placed in front of the adsorbing
section. The pressure drop across the tube must be less than one inch of
mercury at a flow rate of 1 liter per minute.
3.3. Gas chromatograph equipped with a flame ionization detector.
3.4. Column (10-ft x \1/8\-in stainless steel) packed with 80/100
Supelcoport coated with 20 percent SP 2100, 0.1 percent CW 1500.
3.5. An electronic integrator or some other suitable method for
measuring peak area.
3.6. Two-milliliter sample vials with Teflon-lined caps.
3.7. Microliter syringes: 10-microliter (10-[micro]L syringe, and
other convenient sizes for making standards, 1-[micro]L syringe for
sample injections.
3.8. Pipets: 1.0 mL delivery pipets
3.9. Volumetric flasks: convenient sizes for making standard
solutions.
4. Reagents.
4.1. Chromatographic quality carbon disulfide (CS2). Most
commercially available carbon disulfide contains a trace of benzene
which must be removed. It can be removed with the following procedure:
Heat under reflux for 2 to 3 hours, 500 mL of carbon disulfide, 10
mL concentrated sulfuric acid, and 5 drops of concentrated nitric acid.
The benzene is converted to nitrobenzene. The carbon disulfide layer is
removed, dried with anhydrous sodium sulfate, and distilled. The
recovered carbon disulfide should be benzene free. (It has recently been
determined that benzene can also be removed by passing the carbon
disulfide through 13x molecular sieve).
4.2. Benzene, reagent grade.
4.3. p-Cymene, reagent grade, (internal standard).
4.4. Desorbing reagent. The desorbing reagent is prepared by adding
0.05 mL of p-cymene per milliliter of carbon disulfide. (The internal
standard offers a convenient means correcting analytical response for
slight inconsistencies in the size of sample injections. If the external
standard technique is preferred, the internal standard can be
eliminated).
4.5. Purified GC grade helium, hydrogen and air.
5. Procedure.
5.1. Cleaning of equipment. All glassware used for the laboratory
analysis should be properly cleaned and free of organics which could
interfere in the analysis.
5.2. Calibration of personal pumps. Each pump must be calibrated
with a representative charcoal tube in the line.
5.3. Collection and shipping of samples.
5.3.1. Immediately before sampling, break the ends of the tube to
provide an opening at least one-half the internal diameter of the tube
(2 mm).
5.3.2. The smaller section of the charcoal is used as the backup and
should be placed nearest the sampling pump.
5.3.3. The charcoal tube should be placed in a vertical position
during sampling to minimize channeling through the charcoal.
5.3.4 Air being sampled should not be passed through any hose or
tubing before entering the charcoal tube.
5.3.5. A sample size of 10 liters is recommended. Sample at a flow
rate of approximately 0.2 liters per minute. The flow rate should be
known with an accuracy of at least 5 percent.
5.3.6. The charcoal tubes should be capped with the supplied plastic
caps immediately after sampling.
5.3.7. Submit at least one blank tube (a charcoal tube subjected to
the same handling procedures, without having any air drawn through it)
with each set of samples.
[[Page 248]]
5.3.8. Take necessary shipping and packing precautions to minimize
breakage of samples.
5.4. Analysis of samples.
5.4.1. Preparation of samples. In preparation for analysis, each
charcoal tube is scored with a file in front of the first section of
charcoal and broken open. The glass wool is removed and discarded. The
charcoal in the first (larger) section is transferred to a 2-ml vial.
The separating section of foam is removed and discarded; the second
section is transferred to another capped vial. These two sections are
analyzed separately.
5.4.2. Desorption of samples. Prior to analysis, 1.0 mL of desorbing
solution is pipetted into each sample container. The desorbing solution
consists of 0.05 [micro]L internal standard per mL of carbon disulfide.
The sample vials are capped as soon as the solvent is added. Desorption
should be done for 30 minutes with occasional shaking.
5.4.3. GC conditions. Typical operating conditions for the gas
chromatograph are:
1.30 mL/min (60 psig) helium carrier gas flow.
2.30 mL/min (40 psig) hydrogen gas flow to detector.
3.240 mL/min (40 psig) air flow to detector.
4.150 [deg]C injector temperature.
5.250 [deg]C detector temperature.
6.100 [deg]C column temperature.
5.4.4. Injection size. 1 [micro]L.
5.4.5. Measurement of area. The peak areas are measured by an
electronic integrator or some other suitable form of area measurement.
5.4.6. An internal standard procedure is used. The integrator is
calibrated to report results in ppm for a 10 liter air sample after
correction for desorption efficiency.
5.5. Determination of desorption efficiency.
5.5.1. Importance of determination. The desorption efficiency of a
particular compound can vary from one laboratory to another and from one
lot of chemical to another. Thus, it is necessary to determine, at least
once, the percentage of the specific compound that is removed in the
desorption process, provided the same batch of charcoal is used.
5.5.2. Procedure for determining desorption efficiency. The
reference portion of the charcoal tube is removed. To the remaining
portion, amounts representing 0.5X, 1X, and 2X and (X represents target
concentration) based on a 10 L air sample are injected into several
tubes at each level. Dilutions of benzene with carbon disulfide are made
to allow injection of measurable quantities. These tubes are then
allowed to equilibrate at least overnight. Following equilibration they
are analyzed following the same procedure as the samples. Desorption
efficiency is determined by dividing the amount of benzene found by
amount spiked on the tube.
6. Calibration and standards. A series of standards varying in
concentration over the range of interest is prepared and analyzed under
the same GC conditions that will be used on the samples. A calibration
curve is prepared by plotting concentration ([micro]g/mL) versus peak
area.
7. Calculations. Benzene air concentration can be calculated from
the following equation:
mg/m\3\=(A)(B)/(C)(D)
Where:
A=[micro]g/mL benzene, obtained from the calibration curve
B=desorption volume (1 mL)
C=Liters of air sampled
D=desorption efficiency
The concentration in mg/m\3\ can be converted to ppm (at 25[deg] and
760 mm) with following equation:
ppm=(mg/m\3\)(24.46)/(78.11)
Where:
24.46=molar volume of an ideal gas
25 [deg]C and 760 mm
78.11=molecular weight of benzene
8. Backup Data.
8.1 Detection limit--Air Samples.
The detection limit for the analytical procedure is 1.28 ng with a
coefficient of variation of 0.023 at this level. This would be
equivalent to an air concentration of 0.04 ppm for a 10 L air sample.
This amount provided a chromatographic peak that could be identifiable
in the presence of possible interferences. The detection limit data were
obtained by making 1 [micro]L injections of a 1.283 [micro]g/mL
standard.
------------------------------------------------------------------------
Area
Injection Count
------------------------------------------------------------------------
1....................................... 655.4
2....................................... 617.5
3....................................... 662.0 X=640.2
4....................................... 641.1 SD=14.9
5....................................... 636.4 CV=0.023
6....................................... 629.2 .....................
------------------------------------------------------------------------
8.2. Pooled coefficient of variation--Air Samples. The pooled
coefficient of variation for the analytical procedure was determined by
1 [micro]L replicate injections of analytical standards. The standards
were 16.04, 32.08, and 64.16 [micro]g/mL, which are equivalent to 0.5,
1.0, and 2.0 ppm for a 10 L air sample respectively.
------------------------------------------------------------------------
Area Counts
Injection ------------------------------------
0.5 ppm 1.0 ppm 2.0 ppm
------------------------------------------------------------------------
1.................................. 3996.5 8130.2 16481
2.................................. 4059.4 8235.6 16493
3.................................. 4052.0 8307.9 16535
4.................................. 4027.2 8263.2 16609
5.................................. 4046.8 8291.1 16552
6.................................. 4137.9 8288.8 16618
[[Page 249]]
X= 4053.3 8254.0 16548.3
SD= 47.2 62.5 57.1
CV= 0.0116 0.0076 0.0034
CV=0.008........................... .......... .......... ...........
------------------------------------------------------------------------
8.3. Storage data--Air Samples
Samples were generated at 1.03 ppm benzene at 80% relative humidity,
22 [deg]C, and 643 mm. All samples were taken for 50 minutes at 0.2 L/
min. Six samples were analyzed immediately and the rest of the samples
were divided into two groups by fifteen samples each. One group was
stored at refrigerated temperature of -25 [deg]C, and the other group
was stored at ambient temperature (approximately 23 [deg]C). These
samples were analyzed over a period of fifteen days. The results are
tabulated below.
Percent Recovery
------------------------------------------------------------------------
Day analyzed Refrigerated Ambient
------------------------------------------------------------------------
0............................... 97.4 98.7 98.9 97.4 98.7 98.9
0............................... 97.1 100.6 100.9 97.1 100.6 100.9
2............................... 95.8 96.4 95.4 95.4 96.6 96.9
5............................... 93.9 93.7 92.4 92.4 94.3 94.1
9............................... 93.6 95.5 94.6 95.2 95.6 96.6
13.............................. 94.3 95.3 93.7 91.0 95.0 94.6
15.............................. 96.8 95.8 94.2 92.9 96.3 95.9
------------------------------------------------------------------------
8.4. Desorption data.
Samples were prepared by injecting liquid benzene onto the A section
of charcoal tubes. Samples were prepared that would be equivalent to
0.5, 1.0, and 2.0 ppm for a 10 L air sample.
Percent Recovery
------------------------------------------------------------------------
Sample 0.5 ppm 1.0 ppm 2.0 ppm
------------------------------------------------------------------------
1.......................................... 99.4 98.8 99.5
2.......................................... 99.5 98.7 99.7
3.......................................... 99.2 98.6 99.8
4.......................................... 99.4 99.1 100.0
5.......................................... 99.2 99.0 99.7
6.......................................... 99.8 99.1 99.9
X=......................................... 99.4 98.9 99.8
SD=........................................ 0.22 0.21 0.18
CV=........................................ 0.0022 0.0021 0.0018
X=99.4
------------------------------------------------------------------------
8.5. Carbon disulfide.
Carbon disulfide from a number of sources was analyzed for benzene
contamination. The results are given in the following table. The benzene
contamiant can be removed with the procedures given in section 4.1.
------------------------------------------------------------------------
ppm
[micro]g equivalent
Sample Benzene/ (for 10 L
mL air
sample)
------------------------------------------------------------------------
Aldrich Lot 83017................................. 4.20 0.13
Baker Lot 720364.................................. 1.01 0.03
Baker Lot 822351.................................. 1.01 0.03
Malinkrodt Lot WEMP............................... 1.74 0.05
Malinkrodt Lot WDSJ............................... 5.65 0.18
Malinkrodt Lot WHGA............................... 2.90 0.09
Treated CS2....................................... ........ ..........
------------------------------------------------------------------------
II. OSHA Laboratory Method No. 12 for Bulk Samples
Analyte: Benzene.
Matrix: Bulk Samples.
Procedure: Bulk Samples are analyzed directly by high performance
liquid chromatography (HPLC).
Detection limits: 0.01% by volume.
1. Principle of the method.
1.1. An aliquot of the bulk sample to be analyzed is injected into a
liquid chromatograph.
1.2. The peak area for benzene is determined and compared to areas
obtained from standards.
2. Advantages and disadvantages of the method.
2.1. The analytical procedure is quick, sensitive, and reproducible.
2.2. Reanalysis of samples is possible.
2.3. Interferences can be circumvented by proper selection of HPLC
parameters.
2.4. Samples must be free of any particulates that may clog the
capillary tubing in the liquid chromatograph. This may require
distilling the sample or clarifying with a clarification kit.
3. Apparatus.
3.1. Liquid chromatograph equipped with a UV detector.
3.2. HPLC Column that will separate benzene from other components in
the bulk sample being analyzed. The column used for validation studies
was a Waters uBondapack C18, 30 cm x 3.9 mm.
3.3. A clarification kit to remove any particulates in the bulk if
necessary.
3.4. A micro-distillation apparatus to distill any samples if
necessary.
3.5. An electronic integrator or some other suitable method of
measuring peak areas.
3.6. Microliter syringes--10 [micro]L syringe and other convenient
sizes for making standards. 10 [micro]L syringe for sample injections.
3.7. Volumetric flasks, 5 mL and other convenient sizes for
preparing standards and making dilutions.
4. Reagents.
4.1. Benzene, reagent grade.
4.2. HPLC grade water, methyl alcohol, and isopropyl alcohol.
5. Collection and shipment of samples.
5.1. Samples should be transported in glass containers with Teflon-
lined caps.
5.2. Samples should not be put in the same container used for air
samples.
[[Page 250]]
6. Analysis of samples.
6.1. Sample preparation.
If necessary, the samples are distilled or clarified. Samples are
analyzed undiluted. If the benzene concentration is out of the working
range, suitable dilutions are made with isopropyl alcohol.
6.2. HPLC conditions.
The typical operating conditions for the high performance liquid
chromatograph are:
1. Mobile phase--Methyl alcohol/water, 50/50
1. Analytical wavelength--254 nm
3. Injection size--10 [micro]L
6.3. Measurement of peak area and calibration.
Peak areas are measured by an integrator or other suitable means.
The integrator is calibrated to report results % in benzene by volume.
7. Calculations.
Since the integrator is programmed to report results in % benzene by
volume in an undiluted sample, the following equation is used:
% Benzene by Volume=A x B
Where:
A=% by volume on report
B=Dilution Factor
(B=1 for undiluted sample)
8. Backup Data.
8.1. Detection limit--Bulk Samples.
The detection limit for the analytical procedure for bulk samples is
0.88 [micro]g, with a coefficient of variation of 0.019 at this level.
This amount provided a chromatographic peak that could be identifiable
in the presence of possible interferences. The detection limit date were
obtained by making 10 [micro]L injections of a 0.10% by volume standard.
------------------------------------------------------------------------
Injection Area Count
------------------------------------------------------------------------
1.................................... 45386
2.................................... 44214
3.................................... 43822 X=44040.1
4.................................... 44062 SD=852.5
6.................................... 42724 CV=0.019
------------------------------------------------------------------------
8.2. Pooled coefficient of variation--Bulk Samples.
The pooled coefficient of variation for analytical procedure was
determined by 50 [micro]L replicate injections of analytical standards.
The standards were 0.01, 0.02, 0.04, 0.10, 1.0, and 2.0% benzene by
volume.
Area count (Percent)
----------------------------------------------------------------------------------------------------------------
Injection No. 0.01 0.02 0.04 0.10 1.0 2.0
----------------------------------------------------------------------------------------------------------------
1................................................... 45386 84737 166097 448497 4395380 9339150
2................................................... 44241 84300 170832 441299 4590800 9484900
3................................................... 43822 83835 164160 443719 4593200 9557580
4................................................... 44062 84381 164445 444842 4642350 9677060
5................................................... 44006 83012 168398 442564 4646430 9766240
6................................................... 42724 81957 173002 443975 4646260
X = 44040.1 83703.6 167872 444149 4585767 9564986
SD = 852.5 1042.2 3589.8 2459.1 96839.3 166233
CV = 0.0194 0.0125 0.0213 0.0055 0.0211 0.0174
CV = 0.017
----------------------------------------------------------------------------------------------------------------
[52 FR 34562, Sept. 11, 1987, as amended at 54 FR 24334, June 7, 1989;
61 FR 5508, Feb. 13, 1996; 63 FR 1289, Jan. 8, 1998; 63 FR 20099, Apr.
23, 1998; 70 FR 1142, Jan. 5, 2005; 71 FR 16673, Apr. 3, 2006]