Elevated blood mercury levels found in vaccinated infants Preterm infants who receive hepatitis B vaccine are showing elevated blood mercury levels, according to an article in the May 2000 issue of The Journal of Pediatrics. The vaccines contain thimerosal, an organic mercury compound used in several drugs and vaccines. "Preterm infants receive the same dose of hepatitis B vaccine as do term infants, usually within the first days of life," said Gregory V. Stajich, Pharm.D., associate professor of pharmacy practice at Mercer University Southern. "Because dosing adjustments are not made based on birth weight, preterm infants are exposed to relatively more mercury than term infants." Their study, which measured mercury levels in 15 preterm and five full term infants, determined that preterm infants had more than three times the mean mercury levels than did term infants after an initial dose of hepatitis B vaccine. "Because little is known about mercury's effects on the neonate, this early exposure to mercury should raise concern," Stajich said, "especially in preterm infants who are already at greater risk of neurological disorders." Studies have shown that humans are subject to health risks from mercury in fish and in the environment. However, this new study provided the first clinical evidence that neonates develop measurable levels of mercury in their blood following hepatitis B vaccination. "It appears from other studies that mercury in high levels during critical developmental periods may be neurotoxic," the authors state. "Because we found a statistically significant rise in total mercury levels in these infants after vaccination, we are concerned about the possibility of compounding the neurologic risk for these infants." SOURCE: "Researchers find elevated blood mercury levels in preterm infants receiving hepatitis B vaccine," Mercer University School of Medicine, May 13, 2000.