Vaccines remain one of the most effective ways to prevent infectious disease and deaths globally.1 Universal childhood immunization provides herd immunity against many infectious agents and is a policy that has achieved dramatic reductions in common childhood illnesses. Thimerosal, which contains ethyl mercury, has been used as a preservative in vaccines to prevent contamination of multidose vials from bacteria and fungi since the 1930s.2 Although there are clear neurotoxic effects of methyl mercury absorption, ethyl mercury has not been associated with those consequences. Nevertheless, before data were available on risks of thimerosal in vaccines, in 1999 the American Academy of Pediatrics and the US Public Health Service recommended moving toward removing thimerosal use in preservatives as a precautionary measure.3 Thus, thimerosal as a preservative has been removed from most vaccines in the United States, generally resulting in distribution of vaccines in single-dose rather than multidose vials. US...
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January 2013
Commentary|
January 01 2013
Global Vaccination Recommendations and Thimerosal
Walter A. Orenstein, MD;
aDepartments of Medicine, Pediatrics and Global Health, School of Medicine and Rollins School of Public Health,
bEmory Vaccine Center, and
Address correspondence to Walter A. Orenstein, MD, 1462 Clifton Rd, Suite 446, Atlanta, GA 30322. E-mail: [email protected]
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Jerome A. Paulson, MD, FAAP;
Jerome A. Paulson, MD, FAAP
cDepartment of Pediatrics, School of Medicine & Health Sciences, School of Public Health & Health Services, George Washington University, Washington District of Columbia;
dDepartment of Environmental and Occupational Health Children’s National Medical Center, Washington District of Columbia;
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Michael T. Brady, MD, FAAP;
Michael T. Brady, MD, FAAP
eDivision of Infectious Diseases, Nationwide Children’s Hospital, The Ohio State University, Columbus, Ohio; and
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Louis Z. Cooper, MD;
Louis Z. Cooper, MD
fDepartment of Pediatrics, College of Physicians and Surgeons, Columbia University, New York, New York
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Katherine Seib, MSPH
Katherine Seib, MSPH
gHubert Department of Global Health, Emory University, Atlanta, Georgia;
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Address correspondence to Walter A. Orenstein, MD, 1462 Clifton Rd, Suite 446, Atlanta, GA 30322. E-mail: [email protected]
FINANCIAL DISCLOSURE: The authors have indicated they have no financial relationships relevant to this article to disclose.
Pediatrics (2013) 131 (1): 149–151.
Article history
Accepted:
October 09 2012
Citation
Walter A. Orenstein, Jerome A. Paulson, Michael T. Brady, Louis Z. Cooper, Katherine Seib; Global Vaccination Recommendations and Thimerosal. Pediatrics January 2013; 131 (1): 149–151. 10.1542/peds.2012-1760
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Reducing mercury exposure in newborns, infants, and young children is compatible with supporting vaccination.
Reducing mercury exposure in newborns, infants, and young children is compatible with supporting vaccination.
Jose G. Dorea
Department of Nutrition, University of Brasilia, 70919-970 Brasilia, DF, BRAZIL
E-mail: [email protected] Key words: Thimerosal; pediatric vaccines; ethylmercury.
Nobody should dispute the importance of vaccines, global immunization policies or the difficulty faced by those in charge of implementing such policies involving pediatric Thimerosal-containing vaccines (TCVs). Orenstein et al2 commentary correctly points out that Thimerosal use in vaccines should only have special consideration for emergencies and regulating stocks. I fully support this thoughtful stand. However special circumstances do not exclude the necessity for considering the brain's vulnerability for fetuses, newborns, infants, and young children exposure to a known toxicant - ethylmercury.
When the issue of Thimerosal in vaccines was first discussed2 few studies existed on low-doses of mercury in vulnerable infants, and no specific studies looked at ethylmercury. To address these uncertainties, Wigzell2 compared the large mercury load apportioned by infants taking TCVs with what was then known about methylmercury. Wigzell2 concluded for Scandinavians, the neurotoxic uncertainties of Thimerosal vaccines would not constitute a significant addition to infants' daily input from milk or formulas, but recommended that it should be removed from pediatric vaccines. In the USA, the discussion for reducing this mercury exposure resulted in a similar decision 10 years later and has been politically charged since then.
Three chemical forms of Hg have been responsible for significant, unfortunate accidents where children suffered the most: 1) teething powder containing inorganic Hg (calomel or HgCl2) used into the 1930s caused acrodynia and other complications from mercury exposures, 2) in the 1950s tragic events of mass poisonings from industrial discharges in Japan (organic methylmercury in fish; Minamata Disease) and 3) in Iraq and other countries where draught and famine triggered aid (accidental bread poisoning with ethylmercury fungicide). By 1955 teething powders and childhood medications that contained inorganic mercury were withdrawn from the market;3 in the 1970s mercurial fungicides (containing both methyl- and ethylmercury) were banned from agriculture uses; and before 2000, industrial practices discharging mercury wastes had all but ended in both developed and developing countries. As to the methylmercury, most countries have issued fish consumption advisories to help guide consumer awareness on the risks of low-dose exposure.4 Therefore, all of us in health (including Orenstein et al) and environmental sciences welcome the United Nations Environmental Program (UNEP) treaty that promises to control mercury pollution and exposure at the global scale.
Orenstein et al opined that ethylmercury's neurotoxic effects have not been associated with same outcomes as methylmercury. Indeed, given the long latency expected from low doses of mercury, clinically recognizable neurologic complications are unlikely to result from TCVs. Such line of reasoning should not dismiss all accumulated knowledge on ethylmercury toxicity that has been developed in the last 10 years which indicates that untoward effects in susceptible infants are no longer a conjecture.5 Orenstein et al commentary carries a message of unilateral determinism anchored solely on the additional cost of single vials to justify a product (pediatric TCV) abandoned by advanced countries. Pragmatic vaccinologists and conventional toxicologists can work to find cost- effective solutions for Thimerosal-free products compatible with supporting global vaccination programs for newborns, infants, and young children.
References 1. Orenstein WA, Paulson JA, Brady MT, Cooper LZ, Seib K. Global vaccination recommendations and thimerosal. Pediatrics 2013;131(1):149-151. 2. Wigzell H. [Difficulties in replacing mercury as a preservative in bacterial vaccines]. Lakartidningen 1990;87(9):621. 3. Dally A. The rise and fall of pink disease. Soc Hist Med 1997;10(2):291-304. 4. Sagiv SK, Thurston SW, Bellinger DC, Amarasiriwardena C, Korrick SA. Prenatal Exposure to Mercury and Fish Consumption During Pregnancy and Attention-Deficit/Hyperactivity Disorder-Related Behavior in Children. Arch Pediatr Adolesc Med 2012;166(12):1123-1131. 5. Dorea JG. Integrating experimental (in vitro and in vivo) neurotoxicity studies of low-dose thimerosal relevant to vaccines. Neurochem Res 2011;36(6):927-938.
Conflict of Interest:
None declared