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Environ Health Perspect. 2008 April; 116(4): A155.
PMCID: PMC2291008
Perspectives
Correspondence

The Interaction of Agricultural Pesticides and Marginal Iodine Nutrition Status as a Cause of Autism Spectrum Disorders

Roberts et al. (2007) recently reported on the results of their investigation into the relationship between agricultural pesticides and autism spectrum disorders (ASD) and found an association between organochlorines and ASD. One possible mechanism for this relationship is through thyroid disruption (Cheek et al. 1999). There is evidence to suggest that iodine deficiency might be associated with some of the increase in the reported prevalence/incidence of autism (Sullivan and Maberly 2004). For pregnant women who have a marginal iodine nutrition status, the disruption of the thyroid due to exposure to organochlorines could induce iodine deficiency and result in negative effects on the brain of the developing fetus. The U.S. iodine nutrition status has declined markedly over the last three decades, with the current iodine nutrition status among pregnant women being marginal (Caldwell et al. 2005; Hollowell et al. 1998). Because of the current iodine status of pregnant women, the Public Health Committee of the American Thyroid Association (2006) has recently recommended that all pregnant and lactating women take daily iodine supplements. It is interesting that the ASD case mothers tended to be older and more likely to be non-Hispanic white and non-Hispanic black than controls, which is consistent with a poorer iodine nutrition status in older women and in non-Hispanics in the United States (Caldwell et al. 2005; Hollowell et al. 1998).

Ensuring adequate iodine nutrition status of women, especially throughout pregnancy, is an extremely important public health goal. Given the negative effects of a number of environmental chemicals on the thyroid (Zoeller and Crofton 2000), it becomes increasingly important to ensure that all women have an adequate iodine intake and that the recommended approach to assuring adequate iodine nutrition is through a comprehensive iodized salt program (International Council for Control of Iodine Deficiency Disorders/United Nations Children’s Fund/World Health Organization 2001; Sullivan 2007).

Editor’s note

Editor’s note

In accordance with journal policy, Roberts et al. were asked whether they wanted to respond to this letter, but they chose not to do so.

References

  • Caldwell KL, Jones R, Hollowell JG. Urinary iodine concentrations: United States National Health and Nutrition Examination Survey 2001–2002. Thyroid. 2005;15:692–699. [PubMed]
  • Cheek AO, Kow K, Chen J, McLachlan JA. Potential mechanisms of thyroid disruption in humans: interaction of organochlorine compounds with thyroid receptor, transthyretin, and thyroid-binding globulin. Environ Health Perspect. 1999;107:273–278. [PMC free article] [PubMed]
  • Hollowell JG, Staehling NW, Hannon WH, Flanders DW, Gunter EW, Maberly GF, et al. Iodine nutrition in the United States. Trends and public health implications: iodine excretion data from National Health and Nutrition Examination Surveys I and III (1971–1974 and 1988–1994) J Clin Endocrinol Metab. 1998;83:3401–3408. [PubMed]
  • International Council for Control of Iodine Deficiency Disorders, United Nations Children’s Fund/World Health Organization. Assessment of Iodine Deficiency Disorders and Monitoring Their Elimination: A Guide for Programme Managers. 2. 2001. [accessed 7 March 2008]. WHO/NHD/01.1. Available: http://who.int/reproductive-health/docs/iodine_deficiency.pdf.
  • Public Health Committee of the American Thyroid Association. Iodine supplementation for pregnancy and lactation—United States and Canada: recommendations of the American Thyroid Association. Thyroid. 2006;16:949–951. [PubMed]
  • Roberts EM, English PB, Grether JK, Windham GC, Somberg L, Wolff C. Maternal residence near agricultural pesticide applications and autism spectrum disorders among children in the California Central Valley. Environ Health Perspect. 2007;115:1482–1489. [PMC free article] [PubMed]
  • Sullivan KM. Iodine supplementation for pregnancy and lactation—United States and Canada: recommendations of the American Thyroid Association [Letter] Thyroid. 2007;17:483–484. [PubMed]
  • Sullivan KM, Maberly GF. Rapid Responses: Iodine deficiency as a cause of autism? BMJ. 2004. [accessed 7 March 2008]. Available: http://www.bmj.com/cgi/eletters/328/7433/226-c#78048.
  • Zoeller RT, Crofton KM. Thyroid hormone action in fetal brain development and potential for disruption by environmental chemicals. Neurotoxicology. 2000;21:935–945. [PubMed]

Articles from Environmental Health Perspectives are provided here courtesy of National Institute of Environmental Health Science