the relationship between perchlorate in drinking water and cord blood thyroid hormones: first experience from iran

background: considering the controversial information regarding the effects of perchlorate on thyroid function of high risk population as neonates, and given the high prevalence rate of thyroid disorders specially congenital hypothyroidism in our region, this study aims to investigate for the frst time in iran, the relationship between drinking groundwater perchlorate and cord blood thyroid hormones level in an industrial region. methods:   in  this cross-sectional study, drinking groundwater perchlorate  level of  rural areas of zarinshahr, isfahan was measured. simultaneously, cord blood level of thyroid hormones of neonates born in the studied region was measured. thyroid function test of neonates in regions with low and high perchlorate level were compared. results: in this study, 25 tap water samples were obtained for perchlorate measurement. level of cord blood thyroid stimulating hormone (tsh), t4 and t3 of 25 neonates were measured. mean (standard deviation) of perchlorate, tsh, t4 and t3 was 3.59 (5.10) µg/l, 7.81 (4.14) miu/m, 6.06 (0.85) mg/dl, and 63.46 (17.53) mg/dl, respectively. mean levels of thyroid function tests were not different  in  low  (<5 µg/l) and high  level of drinking ground water perchlorate (p > 0.05). conclusions: perchlorate did not appear  to be  related  to  thyroid  function of neonates  in  the studied industrial region. it seems that iodine status of the regions, as well as other environmental contaminants and genetic background,  could  impact on  its  relation with  thyroid  function of neonates.