Abstract
ICR-strain mice (4 weeks of ages) were continually given a low dose (16 ppm), medium dose (30 ppm) and high dose (50 ppm) of methylmercury chloride in foods containing this compound, and mercury levels in the blood (separated into blood cells and plasma portion) and various organs at the acute and chronic onsets of mercury poisoning were assayed using an analyzer developed by the authors. The early onset of severe methylmercury chloride poisoning in female mice was chiefly attributable to sexual differences regarding the amounts of deposited mercury in the brain and other organs; and the mercury levels in all organs of the female mice were higher. The mercury level in the blood cells increased gradually with continuation of the diet and good parallels were seen between the deposited amounts of mercury in various organs and the length of time the mice ingested this diet. The mercury level in the plasma reached a plateau earlier than the onset time of mercury poisoning. The critical concentration of mercury in the blood cells and the brain at the onset of mercury poisoning tended to be low at the chronic stage. In animals on the dose level of 16 ppm, neurological signs evolved at about the half level of the mercury contents in the animals on 50 ppm. The ratios of mercury contents in the animals on 50 ppm. The ratios of mercury distribution in the blood and organs to the distribution into the brain at the onset showed a change in the brain/blood ratio; and the ratio tended to be higher according to the longer administration of methylmercury. In conclusion, the onset of methylmercury chloride poisoning can be predicted by assessing the level of this compound in the brain, in terms of the application period and the content in blood cells.
