A meta-analysis of studies investigating the effects of occupational lead exposure on thyroid hormones

IntroductionInvestigations of the effects of occupational exposure to lead on the concentrations of thyroid hormones in the blood have not produced consistent results. A meta-analysis was performed to assess the effect of occupational exposure to lead on thyroid hormone concentrations using the results from published studies. MethodsGroup means from studies of the thyroid function of persons occupationally exposed to lead were used in a meta-analysis. Differences between the control and exposed groups, and the slopes between thyroid hormone concentrations and log(10) blood lead concentrations or duration of exposure to lead were estimated using mixed models. The hormones analyzed were thyroid stimulating hormone, total and free thyroxine, and total and free triiodothyronine. ResultsNo differences in mean thyroid hormone concentrations were found between the exposed and control groups. No relationships were found between blood lead or the duration of exposure to lead and thyroid hormone concentrations. ConclusionThe results of the analysis do not provide evidence for an effect of occupational lead exposure on thyroid function in men. Am. J. Ind. Med. 59:583-590, 2016. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.