Non-o-PCBs

Huckins, J.N., D.L. Stalling, and J.D. Petty. 1980. Carbon-foam chromatographic separation of non-o,o -chlorine substituted PCBs from Aroclor mixtures. Jour. Assoc. Off. Anal. Chem. 63 750-755. 

Chui et al, [96] have reported that PCDE 74 (2,4,4, 5-tetraCDE) induce 7-ethoxycoumarin O-deethylase activities in trout and PCDE 28 (2,4,4-triCDE) and PCDE 74 (2,4,4, 5-tetraCDE) in rats. The effects of PCDEs were studied by administering PCDEs 100 mg kg 1 day 1 to rats and trout for three days. Chui et al. [96] classified PCDE 28 as a phenobarbital (PB)-type inducer and PCDE 74 a mixed-type inducer. Due to the fact that PCDEs cannot adopt planar configuration, it was suggested that PCDEs cannot act as 3-methyl chloranthrene(MC)-type inducers unlike non-orfho-PCBs. PCBs that are not acutely toxic can still induce toxic and biochemical responses and are PB-type inducers of hepatic drug-metabolizing enzymes [79]. 

In 40 CRF Section 761 Subpart O, the TSCA specifically addresses the requirements for verification of self-implementing cleanup by defining the numbers and locations of samples to be collected from bulk PCB remediation waste and porous surfaces. Section 761 Subpart P specifies the requirements for non-porous surfaces cleanup verification. These regulation-prescribed sampling designs are discussed in detail in Chapter 3.5.2. 

The potential toxicity of OH-PCBs was first investigated in the 1970s. Hydroxylated metabolites were reported having higher potencies for cell toxicity than their parent PCBs [64,193]. Phenolic PCB metabolites were also found to affect mitochondrial respiration and the permeability of the inner membrane. The nature of the effect depended on the structure and pKa of the phenolic metabolite [110,194]. Low binding potencies toward the aryl hydrocarbon receptor (AhR), and low induction capacity of ethoxyresorufin-O-deethylase (EROD), respectively, have been reported for phenolic PCB metabolites of non-ortho CB-77 and mono-ortho CB-105 [34, 195]. Dihydroxylated PCBs may be oxidized to quinones that in turn may react with macromolecules to form adducts, and cause oxidative stress leading to cell death [116]. 

Miyata H, Aozasa O, Ohta S, et al. 1993. Estimated daily intakes of PCDDs, PCDFs and non-ortho coplanar PCBs via drinking water in Japan. Chemosphere 26(8) 1527-1536. 

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