| Time to Re-evaluate the Guideline Value for Manganese in Drinking Water? Karin Ljung and Marie Vahter Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
Abstract
Objective: We reviewed the scientific background for the current health-based World Health Organization (WHO) guideline value for manganese in drinking water. Data sources and extraction: The initial starting point was the background document for the development of the WHO's guideline value for manganese in drinking water as well as other regulations and recommendations on manganese intake levels. Data referred to in these documents were traced back to the original research papers. In addition, we searched for scientific reports on manganese exposure and health effects. Data synthesis: The current health-based guideline value for manganese in drinking water is based partly on debatable assumptions, where information from previous reports has been used without revisiting original scientific articles. Presently, preparation of common infant formulas with water containing manganese concentrations equivalent to the WHO guideline value will result in exceeding the maximum manganese concentration for infant formula. However, there are uncertainties about how this maximum value was derived. Concurrently, there is increasing evidence of negative neurologic effects in children from excessive manganese exposure. Conclusions: The increasing number of studies reporting associations between neurologic symptoms and manganese exposure in infants and children, in combination with the questionable scientific background data used in setting the manganese guideline value for drinking water, certainly warrant a re-evaluation of the guideline value. Further research is needed to understand the causal relationship between manganese exposure and children's health, and to enable an improved risk assessment. Key words: children, drinking water, infants, infant formula, neurotoxicity. Environ Health Perspect 115:1533–1538 (2007) . doi:10.1289/ehp.10316 available via http://dx.doi.org/ [Online 25 July 2007]
Address correspondence to M. Vahter, Institute of Environmental Medicine, Karolinska Institutet, PO Box 210, S-171 77 Stockholm, Sweden. Telephone: 46 8 524 87540. Fax: 46 8 33 69 81. E-mail: Marie.Vahter@ki.se The authors declare they have no competing financial interests. Received 30 March 2007 ; accepted 25 July 2007.
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