Hair mercury levels in pregnant women in Mahshahr, Iran: Fish consumption as a determinant of exposure

MeHg is a well-documented neurotoxicant even at low levels of exposure. Developing brain, in particular, is vulnerable to that. Through bioaccumulating to differing degrees in various fish species, it can have serious adverse effects on the development and functioning of the human central nervous system, especially during prenatal exposure. Therefore, the purpose of this study was to investigate mercury concentration in hair samples of pregnant women living in Mahshahr located in Khuzestan province, Iran. It assessed the association between fish consumption and specific characteristics that can influence exposure. From April to June 2008, 149 pregnant women were invited to participate in this study. An interview administered questionnaire was used to collect information about age, body weight, height, fish (fresh, canned and shrimp) consumption, pregnancy stage, residence duration, education level, family income and number of dental amalgam fillings. The obtained results showed that the geometric mean and range for hair total Hg concentration was 3.52 μg/g (0.44–53.56 μg/g). About 5.4% of mothers had hair total Hg levels in excess of 10 μg/g. Maternal hair mercury level was less than threshold level of WHO (5 μg/g). As expected, there was a clear increase in hair Hg with reported fresh marine fish consumption (p = 0.04). The highest mean for hair mercury level in a group who consumed fish several times per week, was 4.93 μg/g. Moreover, a significant effect of age and residential time on Hg concentration in the hair of the women was found. Pregnant women in Mahshahr consumed large amounts of fish; consequently, most of their offspring were prenatally exposed to moderately high levels of mercury. The results found suggest that pregnant women should decrease their fish consumption.