Summary of Scientific Studies

Data from human studies shows that low levels of perchlorate being detected in some drinking water supplies – typically below 50 ppb – have no adverse health effects on adults, children and newborns.

  • Crump study. This study of newborns and school-age children in three cities in northern Chile, where perchlorate occurs naturally in drinking water in varying concentrations up to 110 ppb, showed no adverse health effects even at the highest levels. View Abstract

  • Lamm and Doemland study. The actual number of cases of congenital hypothyroidism was compared to the expected number in seven counties in Nevada and California where perchlorate is present in water at levels of 4-16 ppb. The study determined that perchlorate in drinking water at these low levels has no measurable effect on thyroid development of newborns. View Abstract

  • Li et al. (2000a). This study examined the thyroid function of more than 23,000 newborns in Las Vegas, where perchlorate is found in water up to 15 ppb, and Reno, which has no perchlorate in drinking water. View Abstract

  • Li et al. (2000b). This study, similar to the one above, examined the thyroid function of more than 540 newborns in Las Vegas and Reno. Scientists looked for changes in thyroid stimulating hormone (TSH) as evidence that the Las Vegas newborns were compensating for decreased levels of thyroid hormones. There was no difference in TSH levels in newborns in the two cities. View Abstract

  • Li et al. (2001). The study compared the prevalence of thyroid disease in Medicaid-eligible residents of Clark County, Nevada, which has perchlorate in drinking water up to 24 ppb, to Medicaid-eligible residents in other Nevada counties where perchlorate is not present in drinking water. It found no evidence of a higher rate of any thyroid disease in Clark County. View Abstract