To evaluate the potential role of endocrine disruption in the decline of pelagic fishes in the San Francisco Bay Delta of California, various surface water samples were collected, extracted, and found to elicit estrogenic activity in laboratory fish. Chemical analysis of the estrogenic samples indicated 2 pesticides (bifenthrin, diuron), 2 alkyphenols (AP), and mixtures of 2 types of alkyphenol polyethoxylates (APEOs). Evaluation of estrogenic activity was further characterized by in vitro bioassays using rainbow trout hepatocytes (Oncorhynchus mykiss) and in vivo studies with Japanese medaka (Oryzias latipes). In the in vitro bioassays, hepatocytes exposed to the pesticides alone or in combination with the AP/APEO mixtures at concentrations observed in surface waters failed to show estrogenic activity (induction of vitelloginin mRNA). In the in vivo bioassays, medaka exposed to individual pesticides or to AP/APEO alone did not have elevated VTG at ambient concentrations. However, when the pesticides were combined with AP/APEOs in the 7-day exposure a significant increase in VTG was observed. Exposure to a 5-fold higher concentration of the AP/APEO mixture alone also significantly induced VTG. In contrast to earlier studies with permethrin, biotransformation of bifenthrin to estrogenic metabolites was not observed in medaka liver microsomes and cytochrome P450 was not induced with AP/APEO treatment. These results showed that mixtures of pesticides with significantly different modes of action and AP/APEOs at environmentally relevant concentrations may be associated with estrogenic activity measured in water extracts and feral fish that have been shown to be in population decline in the San Francisco Bay Delta.

The ubiquitous presence of alkylphenol ethoxylates in the environment as well as concern for endocrine disruption effects in biota caused by their degradation products (such as octyl- and nonylphenol) has raised interest in the environmental fate of these compounds. As part of an effort to model their behavior in a subestuary of the Chesapeake Bay, a quantitative method for the analysis of octyl- and nonylphenol, and their ethoxylates (1-5) in water and sediment was developed. Extraction procedures are based on solid-phase extraction techniques. Identification and quantitation of the analytes is done by liquid chromatography coupled to tandem mass spectrometry. Instrument detection limits for the compounds ranged from 0.1 to 9 pg injected on column, which allowed method detection limits of 0.04-3 ng/L in water and 0.2-13 ng/g of dry weight in sediment. The method was used to analyze water and sediment from the Back River, MD, where concentrations for the individual compounds ranged from <8 to 200 ng/L in water and <9 to 6700 ng/g of dry weight in sediment. Additionally, structural information obtained in the mass spectrometer is presented that supports previous observations that nonylphenol and its ethoxylates are composed mainly of isomers with a tertiary alpha-carbon.

The fate of a comprehensive group of nonylphenol and octylphenol ethoxylates (APEOs) and several of their carboxylated derivatives was studied in three American wastewatertreatment plants (WWTPs), two of which included advanced treatment. Influent and effluent concentrations of the alkylphenolic compounds (APEs) in the three plants were very similar, but effluent concentrations showed a seasonal dependency: both carboxylate and ethoxylate concentrations in the effluents were higher in winter than in summer. Sorption to particulate matter was higher for nonylphenolic compounds than for their octylphenolic counterparts, in agreement with their difference in Kow values. Both effluent concentrations and the removal efficiency of the APEOs were strongly correlated to water temperature, but no correlation was found with suspended solids or organic carbon removal. Although APEO removal from wastewater was high, overall removal from the WWTPs, including APEOs in waste sludge and transformation products, was relatively low and suggested that advanced treatment does not invariably result in better APEO removal. Additionally, a survey of urban sewers suggested that household products still constitute an important source of the APEOs reaching WWTPs.

To evaluate the occurrence and sources of compounds capable of feminizing fish in agriculturally impacted waterways of the Central Valley of California, water samples were extracted and subjected to chemical analyses as well as in vitro and in vivo measurements of vitellogenin in juvenile rainbow trout (Oncorhynchus mykiss). Among the 16 sites sampled, 6 locations frequently exhibited elevated concentrations of estrogenic substances with 17beta-estradiol equivalents up to 242 ng/L in vitro and 12 microg/kg in vivo. The patterns of activity varied among sites, with two sites showing elevated activity only in vitro, two showing elevated activity only in vivo, and two showing elevated activity in both assays. Sequential elution of solid-phase extraction (SPE) disks followed by bioassay-guided fractionation was used to characterize water samples from the two locations where activity was observed in both bioassays. The highest estrogenic activity was observed in the most nonpolar fractions (80-100% methanol eluent) from the Napa River, while most of the activity in the Sacramento River Delta eluted in the 60% methanol eluent. Quantitative analyses of SPE extracts and additional HPLC fractionation of the SPE extracts by GC-MS/MS and LC-MS/MS indicated concentrations of steroid hormones, alkylphenol polyethoxylates, and herbicides that were at least 1-3 orders of magnitude below bioassay 17beta-estradiol equivalent calculations. Given the different patterns of activity and chemical properties of the estrogenic compounds, it appears that estrogenic activity in these agriculturally impacted surface waters is attributable to multiple compounds. Further investigation is needed to identify the compounds causing the estrogenic activity and to determine the potential impacts of these compounds on feral fish.