Opinion ID: 663703
Heading Depth: 4
Heading Rank: 2

Heading: Bioconcentration Factor (BCF)

Text: 33 Based on EPA laboratory studies, dioxin is more soluble in fat tissues than it is in water. As a result, it tends to accumulate in fish fat tissues at concentrations higher than those present in the water. By averaging the fat content of fish likely to be eaten by an exposed population, a generic BCF can be calculated that reflects dioxin's presence in fish as some multiple of its concentration in ambient water. In its 1984 dioxin criteria document, EPA calculates a dioxin BCF of 5000 for fish of average (3%) lipid 14 content. Maryland and Virginia used this BCF figure, inter alia, to derive their numeric water quality criteria. 34 Appellants challenge EPA's use and approval of a 5000 BCF. They essentially contend that the 5000 BCF figure is outdated because the latest scientific research suggests that a higher BCF should be used. Citing the administrative record, appellants emphasize that: (1) EPA admits that scientific literature and research has changed significantly since preparation of the 1984 dioxin criteria document; (2) EPA further admits that BCF factors now range from 26,000 to 150,000, depending on test species; (3) Virginia conducted a state-specific study which revealed a BCF calculation of 22,000; and (4) Maryland refused to conduct such a study. Appellants contend that, taking all of these factors into account, EPA ignored all the current scientific data and simply defaulted to its old BCF assumption. Appellants argue that EPA acted arbitrarily and improperly in not requiring a higher BCF, especially when Virginia and Maryland chose less stringent factors for cancer potency and risk. We disagree. 35 Once again, we are confronted with an area dominated by complex scientific inquiry and judgment. Although EPA is aware that some recent BCF studies suggested a higher BCF than 5000, EPA maintains that such results are inconclusive and that no compelling scientific evidence indicates that a 5000 BCF is no longer within the range of scientific defensibility. We simply are not in a position to second-guess this technical decision by administrative experts. A review of the record does indicate that several more recent BCF studies have been conducted and that some have suggested a higher BCF; however, the court concludes that the best course of action is to leave this debate to the world of science to ultimately be resolved by those with specialized training in this field. Upon a careful review of the administrative record, we find no clear evidence showing that the 5000 BCF figure is not supported by sound scientific rationale. Accordingly, we hold that EPA did not act arbitrarily in approving the BCF figure used by Maryland and Virginia, and that EPA has made a rational connection between the facts found in the administrative record and its choice to approve the BCF figure. EPA's approval of the 5000 BCF will not be disturbed.