Hair mercury in breast-fed infants exposed to thimerosal-preserved vaccines
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Because of uncertainties associated with a possible rise in neuro-developmental deficits among vaccinated children, thimerosal-preserved vaccines have not been used since 2004 in the USA (with the exception of thimerosal-containing influenza vaccines which are routinely recommended for administration to pregnant women and children), and the EU but are widely produced and used in other countries. We investigated the impact of thimerosal on the total Hg in hair of 82 breast-fed infants during the first 6 months of life. The infants received three doses of the hepatitis-B vaccine (at birth, 1 and 6 months) and three DTP (diphtheria, tetanus, and pertussis) doses at 2, 4 and 6 months, according to the immunization schedule recommended by the Ministry of Health of Brazil. The thimerosal in vaccines provided an ethylmercury (EtHg) exposure of 25 μgHg at birth, 30, 60 and 120 days, and 50 μgHg at 180 days. The exposure to vaccine-EtHg represents 80% of that expected from total breast milk-Hg in the first month but only 40% of the expected exposure integrated in the 6 months of breastfeeding. However, the Hg exposure corrected for body weight at the day of immunization was much higher from thimerosal- EtHg (5.7 to 11.3 μgHg/kg b.w.) than from breastfeeding (0.266 μgHg/kg b.w.). While mothers showed a relative decrease (−57%) in total hair-Hg during the 6 months lactation there was substantial increase in the infant’s hair-Hg (446%). We speculate that dose and parenteral mode of thimerosal-EtHg exposure modulated the relative increase in hair-Hg of breast-fed infants at 6 months of age.
KeywordsThiomersal Ethyl-mercury Methyl-mercury Breastfeeding Immunization
difteria tetanus and pertussis
polyunsatured fatty acids
We are greatly in debt to the mothers for their participation in the study, to the staff and directors (Marinês R. dos Santos Cezar, Tereza Cristina Ramos, Daniele Brasil, Katia Wendt, Katiane G. Brandão, Laura Jane Marques) of the Hospitals (Hospital de Base Ary Pinheiro, Hospital Panamericano and Hospital Regina Pacis), Dr. Cezar Augusto Bezerra B. de Araújo (State Coordinator of the PNI-MS), the staff of the Fundação Universidade Federal de Rondônia and the Universidade Federal do Rio de Janeiro.
This work was supported by United Nations Educational, Scientific and Cultural Organization - UNESCO, Ministério da Saúde do Brasil (SC27824/2005/914BRA2000 Decit PRODOC) and The National Research Council of Brazil-CNPq (PNOPG project-55.0882/01-4 PPG7, project-556985/2005-2).
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