title: Uncertainty analysis of dioxin-like polychlorinated biphenyls-related toxic equivalents in fish.
abstract: The toxic equivalent (TEQ) concept is widely used to assess toxicity potential of a dioxin-like chemical mixture. The TEQ approach converts concentrations of various dioxin-like compounds into a single concentration that is toxicologically equivalent to the most toxic dioxin compound, 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), using toxic equivalency factors (TEFs). It has been shown that in the absence of costly measurements of dioxin-like polychlorinated biphenyls (dl-PCBs) in fish, relatively inexpensive measurements of total PCB can be utilized to estimate dl-PCB-related TEQ (i.e., TEQ(dl-PCB)). The present study assesses the impacts of uncertainties in dl-PCB measurements and estimates, and mammalian TEFs on TEQ(dl-PCB) using the Monte Carlo technique. The analysis suggests that measurement errors for dl-PCBs translate into up to 1.3-fold uncertainty in TEQ(dl-PCB), while uncertainties in estimates of dl-PCBs generally produce up to a threefold uncertainty in TEQ(dl-PCB). In contrast, the uncertainty due to TEFs normally ranges 10- to 13-fold and spans over 30- to 40-fold under extreme cases. For 2005 TEFs, PCB-126 is the dominating contributor to uncertainty in TEQ(dl-PCB). When we considered uncertainties in the TEFs and estimated dl-PCB concentrations simultaneously, there was little increase in uncertainty in TEQ(dl-PCB) that was already produced by the TEFs only. These results indicate that the dl-PCB composition in fish and/or the relationship between total PCB and TEQ(dl-PCB) can be utilized to estimate TEQ(dl-PCB) with reasonable confidence.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada.sbhavsar@utoronto.ca
authors.forename: Satyendra P
authors.initials: SP
authors.lastname: Bhavsar
authors.forename: Alan
authors.initials: A
authors.lastname: Hayton
authors.forename: Donald A
authors.initials: DA
authors.lastname: Jackson
mesh_terms: D000818:Animals; D005399:Fishes; D011078:Polychlorinated Biphenyls / Q000633:toxicity*; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D000072317:Polychlorinated Dibenzodioxins; D014874:Water Pollutants, Chemical; D011078:Polychlorinated Biphenyls