Opinion ID: 365968
Heading Depth: 4
Heading Rank: 3

Heading: Degradability

Text: 104 EPA summarized a number of studies concerning the degradation of both less and more chlorinated PCBs by living organisms. PCBs were shown to resist degradation, to bioaccumulate (build up) to high levels in simple organisms, and then to bioaccumulate further as those simple organisms are consumed by higher organisms. 104 42 Fed.Reg. 6539-41. When degradation does occur, it may result in creation of other harmful substances, either as intermediates, or as end products of degradation. 105 Industry petitioners disputed EPA's evidence, and produced their own evidence that less chlorinated PCBs are more easily metabolized and eliminated, and less likely to bioaccumulate than more chlorinated PCBs. They also contended that these substances degrade by safe routes into non-dangerous substances. App. I 209-12, 237-39. 105 However, the conclusions advanced by industry petitioners do not necessarily weaken the support for EPA's prohibition. It was not necessary for EPA to prove that less chlorinated PCBs were as dangerous as more chlorinated PCBs in order to justify a prohibition. The central issue is not whether less chlorinated PCBs are less degradable than more chlorinated PCBs, but whether less chlorinated PCBs are insufficiently degradable. Our task in reviewing the record is not to choose between these conflicting studies, but rather to determine whether EPA's decision had substantial evidence on the whole record. Viewed as a whole, the record provided substantial support for EPA's conclusions. 106