Environ. Sci. Technol. 2002, 36, 4005-4006
Comment on “Pharmaceuticals, Hormones, and Other Organic Wastewater Contaminants in U.S. Streams, 1999-2000: A National Reconnaissance” The recently published USGS nationwide survey (1) is a valuable contribution to the risk assessment process for assessing the post-consumer impact of medicines that have become an integral component of modern society and that are responsible for improving the well-being of the world’s citizens. In reviewing the USGS data, it was notable that the reported synthetic hormone concentrations, in particular 17R-ethinyl estradiol (EE2), were substantially higher than those anticipated based on two complementary lines of reasoning: (i) the estimated concentration that would be expected to enter surface waters based on known EE2 usage rates and (ii) previously published surface water values. The U.S. Food and Drug Administration (FDA) has established guidance (2) for conducting environmental assessments (EA). EA require that an expected introductory concentration (EIC) be calculated based on yearly usage estimates and average POTW flow (2). An EIC for EE2 was calculated using a conservative usage estimate of 170 kg/yr (FDA’s Review of Estrogen; 3) as compared to slightly lower estimates provided by IMS Health Incorporated. The EIC (3.8 ng/L) is plotted in Figure 1 as a reference point to the concentration that would be expected as a worst-case estimate with no metabolism, biodegradation, or dilution. A very similar model is established by the European Medical
Agency (EMEA; 4) for calculating predicted environmental concentrations in surface waters (PECsw ) EIC/10). According to that model, the PECsw in German surface waters is 0.5 ng/L based on German sales data (5). A comprehensive literature survey reveals references 6-15 reporting EE2 surface water concentrations measured in the United States, the United Kingdom, The Netherlands, or Germany. Countries represent developed regions of the world where EE2 usage would likely be similar. Analytical methods either employ immunoassay [4], GC/MS [2], HPLC/MS [1], or GC/MS/MS [3] techniques. (Numbers in [ ] indicate methods or types of water samples used.) Sample preparation used both filtered [6] and unfiltered [4] water samples, followed by any of the following, alone or in combination: lyophilization, solid phase or liquid extraction, fractionation. Two studies (8, 15) used a glucuronidase digestion step in order to separate the glucuronide metabolites from the parent compound, which otherwise are erroneously determined as EE2. Sample recoveries were typically greater than 70%, although one reference obtained only 10-30%. Three other references did not provide any recovery data. The substantial disparity between both the estimated and the previously published EE2 data is demonstrated in Figure 1. Data were plotted as either minimum and maximum values or individual data points, depending upon what was reported in the reference. In cases where no EE2 was detected, the assay limit of detection (LOD) was plotted. While 84% of the reported USGS values were below the limit of detection, 16% of the USGS data is approximately 1-3 orders of magnitude (10-1000 times) greater than either the estimated effluent concentrations (EIC) or the previously published surface water values. USGS data range from its
FIGURE 1. Reported ethinyl estradiol concentration in surface water. 10.1021/es0200903 CCC: $22.00 Published on Web 08/14/2002
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minimum detectable concentration of
