(PT063A) Estimating ethinylestradiol levels in sewage effluent originating from oral contraceptive usage.
O'Brien, T,
ABSTRACT- Oral contraceptives contain the synthetic estrogen, ethinylestradiol (EE2). Their widespread usage may serve as a source of trace levels of estrogens in the environment. Based on the NHANES 1999-2000 data, approximately 12,000,000 U.S. women of ages 20 years and older take individual oral contraceptive doses containing an average of 35 mg EE2 per day. Women taking oral contraceptives excrete EE2 via urine and feces. EE2 from oral contraceptives can enter sewage systems either through excretion or direct disposal of unused drugs. Based on values for percent excretion and usage from the published literature, a range of influent concentrations was estimated. For the excretion route, a range of approximately 0.6 to 2.2 ng/L in sewage treatment plant influent was estimated. For the direct disposal route, an influent concentration of 2.4 ng/L was estimated as a worst case scenario by assuming 100% direct disposal. Assuming 85% to 90% removal of EE2 at STP, an effluent range of 0.06 to 0.4 ng/L EE2 was estimated for the U.S. When STP effluent is discharged into surface waters, EE2 concentrations will be diluted, depending on the volume of the receiving waters. For effluent dominated streams, the levels of EE2 are potentially within the range where documented effects, including intersex in medaka and vitellogenesis induction in male rainbow trout, were observed in aquatic wildlife species. Disclaimer: The views expressed in this paper are those of the author and do not necessarily reflect the views or policies of the U.S. Environmental Protection Agency.
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