Comparison of Blood and Brain Mercury Levels in Infant Monkeys Exposed to Methylmercury or Vaccines Containing Thimerosal

摘要

Thimerosal is a preservative that has been used in manufacturing vaccines since the 1930s. Reports have indicated that infants can receive ethylmercury (in the form of thimerosal) at or above the Environmental Protection Agency (EPA) guidelines for methylmercury (MeHg) exposure, depending on the exact vaccinations, schedule, and size of the infant. This study compared the systemic disposition and brain distribution of total and inorganic mercury in infant monkeys following thimerosal exposure with infants exposed to MeHg. Monkeys were exposed to MeHg (via oral gavage) or vaccines containing thimerosal (via i.m. injection) at birth and 1, 2, and 3 weeks of age. Total blood mercury (Hg) levels were determined 2, 4 and 7 days after each exposure. Total and inorganic brain Hg levels were assessed 2, 4, 7 or 28 days after the last exposure. The initial and terminal half-life of Hg in blood following thimerosal exposure was 2.1 and 8.6 days, which are significantly shorter than the elimination half-life of Hg following MeHg exposure at 21.5 days.