Generation and dose as modifying factors of inorganic mercury accumulation in brain, liver, and kidneys of rats fed methylmercury.

Through three generations, male rats were fed a commercial chow supplemented with four levels of methyl mercury; the average mercury concentrations were 0.038, 0.18, 7.23, and 33.92 nmol Hg/g food for control, low, middle, and high dose groups, respectively. No clinical abnormalities except enlarged kidneys were found in these animals. The effects of dose and generation on tissue distribution and accumulation of inorganic mercury and total mercury were studied in the brain, kidneys, and liver. The dose level of methyl mercury greatly determined the organ accumulation of total mercury and inorganic mercury, as well as the ratio of inorganic mercury concentration to total mercury concentration (I/T) in organs. The I/T ratio was inversely related to the dose level of methyl mercury. With generational procession, the most notable change was found in the liver, i.e., the increasing I/T ratio and the decreasing total mercury accumulation at any dose level. In contrast, the I/T ratio in the kidney showed no constant tendency with generation. The present results suggest that the generational enhancement of inorganic mercury formation from methyl mercury occurs mainly in the liver.