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.

Rees, JR, Sturup, S, Chen, C, Folt, C, and Karagas, MR. Toenail mercury and dietary fish consumption. Journal of Exposure Analysis and Environmental Epidemiology 2007 17:25-30.