In some women abnormally high levels of the common and pervasive chemical perchlorate may lead to adverse effects in their offspring. The study in the Journal of Clinical Endocrinology  &  Metabolism says is the first of its kind to shed light on the possible harmful side effects of perchlorate in mothers and their children.  

Perchlorate is a natural chemical that is also manufactured to produce things like rocket fuel and fireworks. Some studies have linked it to disruption the thyroid’s ability to produce hormones needed for normal growth and development.

Because of that hypothesis, the United States Environmental Protection Agency is evaluating the available peer-reviewed science on perchlorate health effects and exposure, and also evaluating laboratory methods for measuring it in drinking water.  Once the analyses are complete and it is determined if there is an issue, they will propose a national primary drinking water regulation for perchlorate. 

Using data from the Controlled Antenatal Thyroid Study (CATS) cohort, researchers at Boston University School of Medicine and Cardiff University created an epidemiological link to possible effects of perchlorate on children born to mothers with above average levels of this substance in their system. They matched 487 mother-child pairs from women with underactive thyroid glands and in the 50 women with the highest levels of perchlorate in their body, their offspring had below average IQ levels when compared to other children.  It's a causalation claim but the EPA is quite good about separating controlled studies from epidemiology curve-matching.

"The reason people really care about perchlorate is because it is ubiquitous. It's everywhere," said Elizabeth Pearce, MD, MSc, associate professor of medicine at Boston University School of Medicine. "Prior studies have already shown perchlorate, at low levels, can be found in each and every one of us."

According to Pearce, previous studies have attempted to implicate this anti-thyroid activity in pregnant mothers as a possible cause of hypothyroidism, or an underactive thyroid gland. Hypothyroidism in newborns and children can lead to an array of unwelcome side effects, including below average intelligence.