Environmental mercury exposure in children: South China's experience

Abstract

Background: Environmental mercury levels significantly increased in the past decades following its increase in industrial applications. In spite of an increasing concern on the potential harmful effects of mercury on children, there is no reported data for the Chinese population. The relationship between dietary habit and environmental mercury exposure in Chinese children was studied. Methods: The hair and blood mercury levels of Chinese children aged above 3 years in 2000 March to September, were studied. Sociodemographic data, dietary habits of the past 6 months, and other risk factors for environmental mercury exposure were collected. Those children with blood mercury levels above the toxic range (i.e. > 45 nmol/L) and their family members were further evaluated and their blood and hair mercury levels were monitored before and after Fishing-Moratorium period (June to August 2000) in South China Sea. Results: Altogether, 137 Chinese children (mean age, 7.2 years) were recruited. The mean hair mercury level was 2.2 p.p.m and the mean blood mercury level was 17.6 nmol/L. There was a strong correlation (r = 0.88) between hair and blood mercury levels in our cohort. Frequency of fish consumption correlated with hair (r =0.51) and blood (r = 0.54) mercury levels. For those children who consumed fish more than 3 times/week, hair and blood mercury levels were twice as high as those who consumed fish 1-3 times/week and threefold of those who never consumed fish. Five children and 12 family members had toxic blood mercury levels. Their blood (P < 0.0001) and hair (P = 0.02) mercury levels dropped significantly after reducing fish consumption during Fishing-Moratorium period. Conclusion: Both blood and hair (i.e. Tissue) mercury levels of children in Hong Kong was elevated and correlated with the frequency of fish consumption.