[Code of Federal Regulations]
[Title 40, Volume 28]
[Revised as of July 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR766.3]

[Page 805-806]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 766--DIBENZO-PARA-DIOXINS/DIBENZOFURANS--Table of Contents
 
                      Subpart A--General Provisions
 
Sec. 766.3  Definitions.

    The definitions in section 3 of TSCA and the definitions of 
Secs. 704.3, 716.3, 717.3, and 790.3 of this chapter also apply to this 
part.
    Congener means any one particular member of a class of chemical 
substances. A specific congener is denoted by unique chemical structure, 
for example 2,3,7,8-tetrachlorodibenzofuran.
    Dibenzofuran means any of a family of compounds which has as a 
nucleus a triple-ring structure consisting of two benzene rings 
connected through a pair of bridges between the benzene rings. The 
bridges are a carbon-carbon bridge and a carbon-oxygen-carbon bridge at 
both substitution positions.
    Dibenzo-p-dioxin or dioxin means any of a family of compounds which 
has as a nucleus a triple-ring structure consisting of two benzene rings 
connected through a pair of oxygen atoms.
    Guidelines means the Midwest Research Institute (MRI) publication 
Guidelines for the Determination of Polyhalogenated Dioxins and 
Dibenzofurans in Commercial Products, EPA contract No. 68-02-3938; MRI 
Project No. 8201-A(41), 1985.
    HDD or 2,3,7,8-HDD means any of the dibenzo-p-dioxins totally 
chlorinated or totally brominated at the following positions on the 
molecular structure: 2,3,7,8; 1,2,3,7,8; 1,2,3,4,7,8; 1,2,3,6,7,8; 
1,2,3,7,8,9; and 1,2,3,4,7,8,9.
    HDF or 2,3,7,8-HDF means any of the dibenzofurans totally 
chlorinated or totally brominated at the following positions on the 
molecular structure: 2,3,7,8; 1,2,3,7,8; 2,3,4,7,8; 1,2,3,4,7,8; 
1,2,3,6,7,8; 1,2,3,7,8,9; 2,3,4,6,7,8; 1,2,3,4,6,7,8; and 1,2,3,4,7,8,9.
    Homolog means a group of isomers that have the same degree of 
halogenation. For example, the homologous class of tetrachlorodibenzo-p-
dioxins consists of all dibenzo-p-dioxins containing four chlorine 
atoms. When the homologous classes discussed in this part are referred 
to, the following abbreviations for the prefix denoting the number of 
halogens are used:
    tetra-, T (4 atoms)
    penta-, Pe (5 atoms)
    hexa-, Hx (6 atoms)
    hepta-, Hp (7 atoms)

    HRGC means high resolution gas chromatography.
    HRMS means high resolution mass spectrometry.
    Level of quantitation or LOQ means the lowest concentration at which 
HDDs/HDFs can be reproducibly measured in a specific chemical substance 
within specified confidence limits, as described in this part.
    Polybrominated dibenzofurans refers to any member of a class of 
dibenzofurans with two to eight bromine substituents.
    Polybrominated dibenzo-p-dioxin or PBDD means to any member of a 
class of dibenzo-p-dioxins with two to eight bromine substituents.
    Polychlorinated dibenzofuran means any member of a class of 
dibenzofurans with two to eight chlorine substituents.
    Polychlorinated dibenzo-p-dioxin or PCDD means any member of a class 
of

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dibenzo-p-dioxins with two to eight chlorine substituents.
    Polyhalogenated dibenzofuran or PHDF means any member of a class of 
dibenzofurans containing two to eight chlorine, bromine, or a 
combination of chlorine and bromine substituents.
    Polyhalogenated dibenzo-p-dioxin or PHDD means any member of a class 
of dibenzo-p-dioxins containing two to eight chlorine substituents or 
two to eight bromine substituents.
    Positive test result means: (1) Any resolvable gas chromatographic 
peak for any 2,3,7,8-HDD or HDF which exceeds the LOQ listed under 
Sec. 766.27 for that congener, or (2) exceeds LOQs approved by EPA under 
Sec. 766.28.
    Precursor means a chemical substance which is not contaminated due 
to the process conditions under which it is manufactured, but because of 
its molecular structure, and under favorable process conditions, it may 
cause or aid the formation of HDDs/HDFs in other chemicals in which it 
is used as a feedstock or intermediate.
    QA means quality assurance.
    QC means quality control.
    Reimbursement period means the period that begins when the data from 
the last test to be completed under this part for a specific chemical 
substance listed in Sec. 766.25 is submitted to EPA, and ends after an 
amount of time equal to that which had been required to develop that 
data or 5 years, whichever is later.
    TSCA means the Toxic Substances Control Act, 15 U.S.C. 2601 et seq.