May 11, 2000
FOR IMMEDIATE RELEASE
Contact: Roban Johnson
(800) 837-2911 or (912) 301-2716
RESEARCHERS FIND ELEVATED BLOOD MERCURY LEVELS IN PRETERM INFANTS RECEIVING HEPATITIS B VACCINE
ATLANTA -- Because preterm infants are at high risk of neurological disorders, protecting them from potential toxins is critical. In the May 2000 issue of The Journal of Pediatrics, researchers report that hepatitis B vaccines containing thimerosal are elevating mercury levels in some preterm infants. Thimerosal is an organic mercury compound used to enhance product stability in several drugs and vaccines.
A team of investigators from Mercer University, the Georgia Poison Center, Grady Health System and Emory University collaborated on a study to measure total mercury levels in preterm and term infants who had received the hepatitis B vaccine. Principal investigator was Gregory V. Stajich, Pharm.D., associate professor of pharmacy practice at Mercer University Southern School of Pharmacy.
"Preterm infants receive the same dose of hepatitis B vaccine as do term infants, usually within the first days of life," Stajich said. "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 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."
Other members of the research team included Gaylord P. Lopez, Pharm.D., and Sokei W. Harry, MPH, of the Georgia Poison Control Center, and William R. Sexson, M.D., Emory University School of Medicine.
The study was supported by a grant from the American Association of Poison Control Centers, Washington, D.C.
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