Methyl Mercury Pharmacokinetics in Man: A Reevaluation

Data taken from Aberget al.((1969)Arch. Environ. Health19,478–484) and Miettinenet al.((1971)Ann. Clin. Res.3,116–122) were analyzed by means of models that describe methyl mercury pharmacokinetics in man in terms of parent compound only (Model I) or in terms of parent compound plus metabolite, inorganic mercury (Model II). Fecal and urinary excretion of mercury are linear for both models. In Model I all excreted mercury arises from a common pool. This model successfully simulates the time profiles for body total mercury and fecal excretion but fails to explain the continuous increase in daily urinary mercury that occurs for several weeks following methyl mercury administration. In Model II fecal mercury arises from the methyl mercury compartment and urinary mercury from the inorganic mercury compartment. Simulations from this model are comparable to those from Model I for body total mercury and fecal excretion but are significantly more precise for urinary excretion. Model II also accounts for the observation (Miettinenet al.,1971) that blood mercury comprises a steadily declining proportion of body mercury burden for at least 91 days after methyl mercury dosing. Data simulated by means of Model II, using parameters estimated from Aberg's and Miettinen's data sets, predict methyl mercury half-lives of 51 and 56 days, respectively. These values are comparable to the methyl mercury half-life of 44 days reported by Smithet al.((1994)Toxicol. Appl. Pharmacol.128,251–256) and are approximately 70% of half-lives reported by Aberg and Miettinen.