An Assessment of Potential Exposure and Risk from Estrogens in Drinking Water

Article excerpt

BACKGROUND: Detection of estrogens in the environment has raised concerns in recent years because of their potential to affect both wildlife and humans.

OBJECTIVES: We compared exposures to prescribed and naturally occurring estrogens in drinking water to exposures to naturally occurring background levels of estrogens in the diet of children and adults and to four independently derived acceptable daily intakes (ADIs) to determine whether drinking water intakes are larger or smaller than dietary intake or ADIs.

METHODS: We used the Pharmaceutical Assessment and Transport Evaluation (PhATE) model to predict concentrations of estrogens potentially present in drinking water. Predicted drinking water concentrations were combined with default water intake rates to estimate drinking water exposures. Predicted drinking water intakes were compared to dietary intakes and also to ADIs. We present comparisons for individual estrogens as well as combined estrogens.

RESULTS: In the analysis we estimated that a child's exposures to individual prescribed estrogens in drinking water are 730-480,000 times lower (depending upon estrogen type) than exposure to background levels of naturally occurring estrogens in milk. A child's exposure to total estrogens in drinking water (prescribed and naturally occurring) is about 150 times lower than exposure from milk. Adult margins of exposure (MOEs) based on total dietary exposure are about 2 times smaller than those for children. Margins of safety (MOSs) for an adult's exposure to total prescribed estrogens in drinking water vary from about 135 to > 17,000, depending on ADI. MOSs for exposure to total estrogens in drinking water are about 2 times lower than MOSs for prescribed estrogens. Depending on the ADI that is used, MOSs for young children range from 28 to 5,120 for total estrogens (including both prescribed and naturally occurring sources) in drinking water.

CONCLUSIONS: The consistently large MOEs and MOSs strongly suggest that prescribed and total estrogens that may potentially be present in drinking water in the United States are not causing adverse effects in U.S. residents, including sensitive subpopulations.

KEY WORDS: acceptable daily intake, dietary intake, drinking water, environmental sources, estrogen, excretion, PhATE, phytoestrogen, surface water. Environ Health Perspect 118:338--344 (2010). doi:10.1289/ehp.0900654 available via http:lldx.doi.org/ [Online 13 October 2009]

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Detection of estrogens in the environment has raised concerns in recent years because of the potential of these compounds to affect both wildlife and humans. The incomplete removal by publicly owned treatment works (POTWs) of excreted endogenous estrogens and prescribed estrogens leads to their introduction into surface waters and potentially into drinking water sources that rely on surface water. Estrogens, specifically estrone (El), 17[beta]-estradiol (E2), estriol (E3), and ethinyl estradiol (EE2), have been detected in numerous studies of wastewater influents and effluents (Baronti et al. 2000; Belfroid et al. 1999; Desbrow et al. 1998; Ferguson et al. 2001; Heberer 2002; Huang and Sedlak 2001; Huggett et al. 2003; Lagana et al. 2000; Mouatassim-Souali et al. 2003; Nasu et al. 2001; Rodgers-Gray et al. 2000; Spengler et al. 2001; Ternes et al. 1999a, 1999b, 2002), and their presence has been confirmed in U.S. and European surface waters (Aherne and Briggs 1989; Belfroid et al. 1999; Heberer 2002; Kolodziej et al. 2003; Kolpin et al. 2002; Kuch and Ballschmiter 2001). More recently, several estrogens have also been detected in the source water of drinking water treatment plants but not in the finished water (Benotti et al. 2009).

The effects of estrogens on fish and other aquatic organisms have been widely studied (see Caldwell et al. 2008). However, fewer studies have evaluated the potential effects of estrogens in surface water on humans. …