[Difference by sex and age of mercury concentration in red blood cells]

The mercury concentration in red blood cells (RBCs) is one of the most useful indicators for people exposed to methylmercury. Sex- and age-related differences in mercury concentrations in red blood cells were studied by considering fish consumption in 1,253 adults (511 males and 742 females) participating in a mass health examination conducted in a town of Kumamoto Prefecture in 1989. The results were as follows: 1. The mercury concentrations in RBCs showed lognormal distributions for both sexes with a higher mode in males than in females. The geometric mean of the mercury concentrations in the RBCs was 28.5 ng/g (ranging from 5.6 to 71.0 ng/g) for males and 20.4 ng/g (ranging from 3.7 to 70.4 ng/g) for females and was significantly higher in males than in females. The mercury concentration in RBCs decreased with aging for both sexes. 2. The mercury concentrations in RBCs significantly increased with the amount of fish consumption for both sexes. The mercury concentrations in RBCs were significantly higher in drinkers than in non-drinkers for males and the concentrations increased significantly with body weight for females. 3. The mercury concentrations in RBCs were higher in males than in females and decreased with aging for both sexes under conditions of a constant level of fish consumption. 4. In couples who consumed same amount of fish, the mercury concentrations in RBCs were significantly higher in husbands than in wives. These results suggest that the mercury concentrations in RBCs are higher in males than in females and decreases with aging under a constant level of fish consumption.