On the chemical perchlorate, the agency charged with protecting human health and the environment has "evolved" from pressing for a health protective proposal to no regulation at all.
The country's primary government agency in charge of protecting human health and the environment is choosing NOT to regulate a chemical called perchlorate in drinking water.
Is perchlorate hazardous?<p>The answer is "Yes." Perchlorate can interfere with normal brain development in our children.</p><p>Perchlorate is a molecule that <a href="https://toxtown.nlm.nih.gov/chemicals-and-contaminants/perchlorate" target="_blank">looks like iodine</a> to our bodies. Iodine is important because our thyroid glands need it to make thyroid hormone. </p><p>The right amount of thyroid hormone is essential for the human brain to develop properly. This is true from early on in the first trimester of pregnancy well into the second year of childhood. </p><p>Perchlorate can block the ability of our thyroid glands to get enough iodine to make the proper amount of thyroid hormone.</p><p>So, perchlorate is most certainly hazardous. If we are all exposed—even pregnant women and their fetuses—then perchlorate has the potential to damage the developing brain. </p><p>Of course, perchlorate is <a href="https://ehp.niehs.nih.gov/doi/10.1289/ehp358" target="_blank">not the only chemical</a> the fetus and infants are exposed to that can harm brain development, and they very likely produce an additive effect.<br></p>
How much perchlorate is too much?<p>There are many scientific studies in humans to try and determine how much perchlorate it takes to harm our children. Recognize that <em>if</em> we are already exposed to that amount of perchlorate, it is already harming our children and they will never recover from its effects.</p><p>But it is complicated.</p><p>Some studies have shown that measures of perchlorate exposure are associated with lower levels of thyroid hormone, while other studies have not found this. <a href="https://academic.oup.com/jcem/article/102/7/2637/3744980" target="_blank">One study</a> showed that perchlorate was associated with lower thyroid hormone in adolescent girls and boys.</p><p>We know that perchlorate and iodine <em>compete</em> to be taken up by the thyroid gland. Thus, if there is more perchlorate than iodine, perchlorate wins. If the opposite is true, perchlorate loses. </p><p>So, for any exposure level of perchlorate, its ability to block iodine is dependent upon the iodine level. This is very likely part of the explanation for why only some studies show an association between higher perchlorate and lower thyroid hormone.</p><p>But <a href="https://academic.oup.com/jcem/article/99/11/4291/2836745" target="_blank">one study</a>—the only one of its kind—showed that pregnant women with higher levels of perchlorate exposure had children with lower IQ levels. </p><p>The conclusion from the scientific evidence appears to be that some people are being damaged by perchlorate today. </p><p>That seems like a weak statement—unless your child is one of them.</p>
Fireworks, air-bags, rocket fuel, ammunition are all important sources of perchlorate. (Credit: Peter Thoeny - Quality HDR Photography/flickr)