To evaluate the level of maternal and prenatal mercury exposure and to analyze the related factors.

Fifty-nine pregnant women were recruited into this study after obtaining informed consent. Samples were collected at delivery from normal pregnant women who were living in the city of Busan, Korea. Mercury concentrations in maternal and umbilical cord blood samples were measured using a gold-amalgam collection method. The total and methyl mercury levels of 36 of the 59 pregnant women were analyzed after randomization, and the results were compared.

The mean total mercury concentration was 3.16±1.21 ppb and 5.43±2.22 ppb in maternal and cord blood, respectively. The average, maternal blood mercury level was lower than the prescribed toxic limit for human (WHO, 5 ppb), whereas the cord blood mercury was higher. The mercury exposure level exceeded the WHO recommendation in 5 (8.47%) cases of maternal blood and 29 of (49.15%) cord blood. There was a significant correlation between maternal and cord blood mercury concentrations. Total mercury and methyl mercury concentrations of the 36 random pregnant women were 3.06±1.17 ppb, and 2.60±1.11 ppb in maternal blood, and 5.20±2.36 ppb, and 4.70±1.97 ppb in cord blood, respectively. Methyl mercury accounted for 85.0% of the total mercury in maternal blood and 90.4% in cord blood. There was a significant correlation between total and methyl mercury concentrations.

The study results suggest that mercury concentrations of cord blood may be regarded as indicative of high prenatal mercury exposure. Therefore, further studies are necessary to explain the cause of high mercury concentrations in cord blood, and to examine its relationship with various health indices.