Toenail mercury and dietary fish consumption.

New England is one of three areas in the United States with the highest annual deposition of mercury, an established environmental pollutant with a variety of health effects. We measured the mercury content in toenails of 27 individuals in New Hampshire who participated as controls in a health study in 1994-95. The mean total toenail mercury concentration was 0.27 mcg/g (median 0.16; SD 0.27; range 0.04-1.15 mcg/g). The best predictor of toenail mercury levels was the mean combined fish and shellfish consumption measured using four simple questions from a validated food frequency questionnaire. Toenail total mercury content was significantly correlated with the mean average weekly consumption of finfish and shellfish (Spearman correlation coefficient 0.48, P=0.012). Multivariate models confirmed that toenail total mercury concentration was best predicted by total finfish and shellfish consumption.