Iodine intake as a possible cause of discontinuous decline in sperm counts : A re-evaluation of historical and geographic variation in semen quality

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Author(s)

    • Sakamoto Kentaro Q
    • Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University
    • Ishizuka Mayumi
    • Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University
    • Kazusaka Akio
    • Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University
    • Fujita Shoichi
    • Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University

Abstract

In order to examine whether iodine supplements may have caused a global decline in sperm concentrations during the past several decades, the synchronicity of the decline in mean sperm counts and the introduction of iodine supplements was analyzed statistically. A positive correlation between the incidence of thyroid disease and sperm counts has been detected in Europe. In addition, it has been shown that sperm counts began falling around 1965 in the United States, 40years after iodine supplements were introduced. Mean sperm counts before and after 1965 were 111 x 10^6ml and 70 x lO^6/ml, respectively, in calculations weighted by the number of subjects included in each individual publication. The timing of the declines coincided with the introduction of iodine supplements in the United States, France, and the United Kingdom. The implications are that the global decline in sperm concentrations may be caused by iodine intake. Geographical variation in the types of sperm count decline also appears to be present.

Journal

  • Japanese Journal of Veterinary Research

    Japanese Journal of Veterinary Research 52(2), 85-94, 2004-08

    The Graduate School of Veterinary Medicine, Hokkaido University

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