Studies on the relationship between the characteristics of daily food consumption and the concentration of mercury in urine

Abstract

In order to assess the degree of mercury poisoning in the case of occupational and environmental mercury exposure, we commonly used to measure urinary mercury concentration as an indicator. However, it was known that the normal mercury concentrations in the urine of persons who have not been exposed to mercury show a wide range of differences between individuals. The author recently conducted a study to establish the baseline inorganic mercury levels in urine by testing 48 married couples from Niigata, Japan, and investigated the relationship between daily intake of foodstuffs and the variations in urinary mercury levels.The results were as follows:1) Urinary mercury concentration averaged 2.70μg/l for the husband, 2.33μg/l for the wife and 2.51μg/l overall.2) The amount of mercury intake from daily food consumption was similar for husband and wife pairs. It was found that fish and shellfish contributed 50% of the dietary mercury (20.4μg/day a person).3) Urinary mercury concentration was highly correlated for husband and wife pairs (p<0.01). In the case of married couple samples, there was a significant correlation between urinary mercury concentration and the amount of mercury intake from fish and shellfish (p<0.05).4) Considering that (a) intake amounts of mercury from fish and shellfish formed the greater part of dietary mercury as compared with that from other food items and that (b) the form of mercury in fish and shellfish was mainly methylmercury, which has a high affinity in vivo, it cannot be denied that the primary factor in the variations in urinary mercury concentration is related to the amount of fish and shellfish consumed.