Estimation of exposure criteria values for biliary polycyclic aromatic hydrocarbon metabolite concentrations in white suckers (Catostomus commersoni)

A methodology was developed for deriving quantitative exposure criteria use ful for comparing a site or a watershed to a reference condition and for de fining the occurrence of extreme exposures. The prototype method used indic ators of exposures to oil contamination and combustion by-products, naphtha lene (NAPH)-type and benzo[a]pyrene (BaP)-type biliary metabolites from whi te suckers (Catostomus commersoni). The fish were collected from first- to third-order streams in the Regional Environmental Monitoring Assessment Pro gram (REMAP) study of the Eastern Corn Belt Plains ecoregion at randomly se lected sires and from third- or higher-order streams in conjunction with th e Ohio Environmental Protection Agency (OEPA) Biomonitoring Program. which sampled sites of concern and reference sites selected by ecologists. The po lycyclic aromatic hydrocarbon metabolites were measured using fixed-wavelen gth fluorescence with excitation/emission pairs at 290/335 nm for NAPH-type and 380/430 nm for BaP-type metabolites. Exposure criteria values were sel ected for each type of metabolite for both the REMAP study and the OEPA ref erence sites following the recommendations of the International Federation of Clinical Chemistry. Exposure criteria derived for each metabolite were n ot significantly different for REMAP and OEPA reference sites. More than on e half of the OEPA nonreference sites were found to be contaminated, exceed ing criteria values for both types of metabolites. This method for finding meaningful exposure criteria can be used to develop criteria of exposure to other contaminants for other wildlife and other ecosystems.