Trichlorobiphenyls

By treating groups of mice with 2,4, 5-trichIorobiphenyI and [35S]cysteine or [35S]methionine the formation of 4-[35S]methylsulfonyl-2,4, 5-trichlorobiphenyl (194) was indicated and shown to deposit in the lungs. GC-MS analysis confirmed the presence of 194 as the minor component60. 

Sediment samples from a contaminated site were spiked with Arochlor 1242 and incubated at 4°C for several months (Williams and May 1997). Degradation by aerobic organisms in the upper layers of the sediment—but not in those at >15 mm from the surface—occurred with the selective production of di- and trichlorobiphenyls. Some congeners, including... 

An anaerobic bacterial enrichment cnltnre was used to examine the dechlorination of 2,3,4,5-tetrachlorobiphenyl that prodnced 2,3,5-trichlorobiphenyl exclusively. Although there was no alteration in the valnes of 5 C, compound-specific analysis of Arochlor 1268 showed that there was a trend for decreasing C abundance with increasing content of chlorine. This is consistent with dechlorination of the congeners with more chlorine substituents. 

An anaerobic sediment sample was incnbated with 2,3,4,6-tetrachlorobiphenyl at various temperatures between 4 and 66°C (Wn et al. 1997). The main products were 2,4,6- and 2,3,6-trichlorobiphenyl and 2,6-dichlorobiphenyl the first of these was produced maximally and discontinnonsly at 12 and 34°C, the second maximally at 18°C, and the third was dominant from 25 to 30°C. Dechlorination was not observed above 37°C. 

Figure 2A. Diagram of processes included in the QWASI fugacity model showing D values for a trichlorobiphenyl in a lake similar to Lake Michigan.

The first set of calculations illustrates various levels of complexity for one chemical (a trichlorobiphenyl). Figure 3, 4,... 

Figure 6. Level IV calculation for a trichlorobiphenyl showing response to emission changes.

The QUASI fugacity model was then run for a trichlorobiphenyl in a lake the size of Lake Michigan, being approximately 60,000 times the size of the evaluative environment. A detailed justification for the selection of D values is beyond our scope here but in selecting values, we have relied on recent reports by Neely (11), Rogers (15), Armstrong and Swackhamer (16), Thomann (17), and Andren (18). 

Along with degree of chlorination another determinant of PCB metabolism in fish is species. Green sunfish and goldfish rapidly metabolize 2,2, 5-trichlorobiphenyl whereas bullheads and rainbow trout metabolize it slowly (26,29). There is little evidence for PCB metabolism in brook trout fed 4-chloro-, 4,4 -dichloro-, 2,2, 5,5 -tetrachloro- or 2,2, 4,4, 5,5 -hexachloro-biphenyl (31) and this was confirmed in rainbow trout by less than 1% of 2,2, 5,5 -tetrachlorobiphenyl accumulated being recovered as polar metabolites (25). 

Elimination. Rate that PCBs are eliminated by fish is strongly influenced by their rate of metabolism. Figure 7 shows concentration of PCB in green sunfish after being exposed to a high or low dose of 2,2, 5-trichlorobiphenyl or 2,2, 4,5,5r-pentachlorobiphenyl on day 0 and again on day 9 (26). Of these... 

Trichlorobiphenyl Biphenyl chlorinated to a chlorine content of 42 weight percent 80 10... 

Photolytic. Titanium dioxide suspended in an aqueous solution and irradiated with UV light (A, = 365 nm) converted 1,2-dichlorobenzene to carbon dioxide at a significant rate (Matthews, 1986). The sunlight irradiation of 1,2-dichlorobenzene (20 g) in a 100-mL borosilicate glass-stoppered Erlenmeyer flask for 56 d yielded 2,270 ppm 2,3, 4 -trichlorobiphenyl (Uyeta et al, 1976). 

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