[Status and influencing factors of mercury exposure in neonates and their mothers in Zhoushan]

Abstract

Objective: To investigate the status of mercury exposure of neonates and their mothers in Zhoushan City, and analyze the related influencing factors.

Methods: From Aug to Sep, 2004, 408 neonate-mother pairs were cluster sampled at the Third People's Hospital in Dinghai region, Zhoushan City, and a further investigation for the neurobehavioral development of these children was followed up in a year. The contains of mercury of 14 kinds of fish, 5 pieces of each kind bought in markets of Dinghai region were detected.

Results: The geometric mean of cord-blood Hg was 27.81 nmol/L (5.58 microg/L), while that of hair Hg of mothers was 1246.56 microg/kg. 69.9% of pregnant women had surpassed the RfD (reference dose, 0.1 microg/kg/day) for Hg intake. There was a strong correlation between hair and cord blood Hg levels (r = 0.821). The factors influencing cord-blood Hg levels were fish dinners, dwelling time, and fathers smoking or not, while those of hair Hg were fish dinners and dwelling time. The correlation between fish dinners and the cord blood Hg as well as hair Hg were of significance (r = 0.539, 0.481 respectively), the Hg levels were higher in more fish dinners (H = 119.805, 94.384 respectively). The mean fish Hg level at Dinghai region was low (< 0.1 mg/kg), and no samples were higher than 0.5 mg/L. Two samples of cutlassfish and dried eel contained higher Hg than the others, belonging to a middle level (0.1-0.5 mg/kg).

Conclusions: Hg levels in neonates and pregnant women were generally below those considered hazardous, but the safety margin was narrow for some women and supporting efforts should be made to reduce mercury exposure. The main resource of Hg was from eating fish, and it is necessary to investigate the Hg levels in large samples, as to developing the fish advisories for susceptible people.