Chemistry

Peering down the Drain

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Science  18 Jul 2008:
Vol. 321, Issue 5887, pp. 318
DOI: 10.1126/science.321.5887.318a

Recent observations that excreted estrogenic compounds derived from pharmaceuticals can harm fish at concentrations in the ng/liter range have driven researchers with increasing urgency to track the path of these microcontaminants down the drain. Johnson et al. review the various pros and cons of analytical sampling versus modeling approaches toward understanding precisely what flows from the sewer into the wider world. Sampling might seem the most accurate option, but in practice, field conditions vary widely over time and space, necessitating multiple withdrawals; compounds may degrade between acquisition and analysis; and techniques may lack the requisite detection sensitivity. Modeling is a daunting alternative, in light of the numerous factors that must be considered, ranging from human drug consumption and excretion trends, to variations in the effectiveness of sewage treatment protocols, to the range of hydrological features affecting flow dynamics. On the flip side, though, the authors note that models can more easily be scaled to treat diminishingly small concentrations without running into detection thresholds. In cases where physical measurements and model results could be compared, they agreed reassuringly well (often within a factor of 3 or 4), supporting the case for an integrated approach that balances the strengths of each complementary technique. — JSY

Environ. Sci. Technol. 42, 10.1021/es703091r (2008).

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