Quantcast
Health
Shutterstock

EPA: Perchlorate in Drinking Water Can Harm Fetal Brain Development

By Tom Neltner

Pursuant to a consent decree with the Natural Resources Defense Council (NRDC), the U.S. Environmental Protection Agency (EPA) is developing drinking water regulations to protect fetuses and young children from perchlorate, a toxic chemical that inhibits the thyroid's ability to make the hormone T4 essential to brain development. The rulemaking is part of a long process that began in 2011 when the agency made a formal determination that Safe Drinking Water Act standards for perchlorate were needed. Under the consent decree, EPA should propose a standard by October 2018.

In the latest step in that process, EPA's scientists released a draft report in September that, at long last, answers questions posed by its Science Advisory Board in 2013: does perchlorate exposure during the first trimester reduce production of T4 in pregnant women with low iodine consumption? Does reduction in maternal T4 levels in these women adversely affect fetal brain development? According to EPA's scientists, the answers are Yes and Yes.


For several years, EPA and the Food and Drug Administration (FDA) have developed and refined a model that would predict the effect of different doses of perchlorate on levels of T4 in pregnant women. The latest version of the model addresses women during the first trimester, especially those with low iodine intake. This is important because iodine is essential to make T4 (the number four indicates the number of iodine atoms present in the hormone); perchlorate inhibits its transport from the blood into the thyroid. The risk of perchlorate exposure to fetuses in the first trimester is greatest because brain development starts very early and is fully dependent on maternal T4. If the mother gets insufficient iodine to offset the perchlorate inhibition, she will not produce enough T4 for the fetal brain to develop properly. When free T4 (fT4) levels are low but without increase in thyroid stimulating hormone (TSH), the condition is known as hypothyroxinemia. When T4 production is lowered further, the pituitary gland releases TSH to increase T4 production by a feedback loop mechanism.

EPA's scientists reviewed 55 research studies and concluded, "Overall, the results of this literature review lend support to the concept that maternal fT4, especially in the hypothyroxinemic range, is critical to the offspring's proper neurodevelopment" and "the impact of altered fT4 is seen even with small incremental changes in fT4 (and in populations with fT4 across the "normal" range)."From the literature search, EPA identified IQ, motor skills, cognitive and language development and reaction time as measurements of neurodevelopment that enable them to quantify the effects of perchlorate exposure in the first trimester.

EPA also estimated the impact of perchlorate exposure in the population of pregnant women in the first trimester and with low iodine consumption; in other words, how many pregnant women will become hypothyroxinemic due to perchlorate exposure thus increasing the risk of adverse neurodevelopmental effects in their children. They predicted that a dose of:

  • 0.3-0.4 micrograms of perchlorate per kilogram of body weight/day (µg/kg bw/day) is associated with a one percent increase in pregnant women with hypothyroxinemia; and
  • 2.1-2.2 µg/kg bw/day is associated with a five percent increase in pregnant women with hypothyroxinemia.

While these percentages appear small, they represent a significant number of potentially affected children since neurodevelopmental harm is likely irreversible. EPA did not estimate the number of pregnant women or children potentially affected. We did. Based on four million children born in the U.S. each year, an estimated 400,000 were born to women with hypothyroxinemia. A one percent shift in the population of women with hypothyroxinemia associated with perchlorate exposure would correspond to an increase of 4,000 impacted children; if there is a five percent shift, the number of impacted children born to hypothyroxinemic mothers would increase to 20,000.

The agency is accepting public comments until Nov. 20, 2017 and will convene a peer review panel to review its findings in January 2018. After considering the panel's feedback, EPA will develop a Maximum Contaminant Level Goal (MCLG) and, eventually, a drinking water standard for perchlorate. The model's conclusions and identification of a new reference dose are also expected to inform EPA's standards for hypochlorite bleach to limit degradation to perchlorate and FDA's assessment of its decision to allow perchlorate to be added to plastic packaging and food handling equipment at concentrations as high as 1.2 percent.

EDF and NRDC submitted joint comments to EPA supporting the draft report and its analysis. We also made the following general observations:

  • Incremental changes in free T4 (fT4) are fundamental: Critical neurodevelopmental adverse effects could be missed by measuring full range maternal fT4. Windows of susceptibility are common in all organs during development. Hormonal control of brain development is no exception. Therefore, adverse neurodevelopmental outcomes will vary based on the time and duration of decreases in fT4 levels. We appreciate seeing the agency building a model based on this fundamental principle of developmental biology.
  • EPA's scientists provide an essential service: Academic researchers laid a solid foundation for the analysis. Without their work, typically funded by government grants, we would not have the evidence necessary to recognize the harm from perchlorate at the levels under consideration. But it took the independent scientists at EPA, building on a model developed by FDA, to provide the objective rigorous review of the evidence and adapt the model.
Show Comments ()

EcoWatch Daily Newsletter

Sponsored
Food
Vegetables in Whole Foods Market. Masahiro Ihara / CC BY 2.0

Food's Environmental Impact Varies Greatly Between Producers

By Jason Daley

There's no way around it—everything in the grocery store, from nuts and kale to beef and apples, has an environmental impact. Fertilizer causes water pollution, farm fields can encroach on habitat, and a lot of carbon gets released when food is transported from one place to another. But it turns out not every stalk of broccoli or pound of Gouda has the same ecological footprint. A new study of food systems in the journal Science shows the same items sitting next to each other on the shelf can have radically different impacts.

Keep reading... Show less
Politics
U.S. Senator Ted Cruz of Texas. Gage Skidmore / Flickr / CC BY-SA 2.0

GOP Senators Demand Probe of Federal Grants on Climate Change

A group of Republican senators are calling for an investigation of the National Science Foundation (NSF) over a program that "[turns] television meteorologists into climate change evangelists," according to a Wednesday press release from the office of Sen. Ted Cruz (Texas).

Keep reading... Show less
Popular
pxhere

World's Plastic Waste Problem Now Predicted to Reach 111 Million Metric Tonnes by 2030

Mountains of plastic waste are building up around the globe after China implemented a ban on other countries' trash.

By 2030, an estimated 111 million metric tons of single-use drink bottles, food containers and other plastic junk will be displaced because of China's new policy, according to a new paper from University of Georgia researchers, who cited UN global trade data for their study.

Keep reading... Show less
Politics
Children detained at a facility in McAllen, Texas under Trump's "zero tolerance" immigration policy. U.S. Customs and Border Control

Trump Penalizes Migrants Fleeing Climate Crisis He Ignores

The impacts of climate change do not respect international borders. If they did, it wouldn't be the case that the countries who have done the least to contribute to global carbon dioxide emissions are expected to suffer disproportionately from their effects.

But as climate refugees begin to flee deteriorating conditions, they are already finding that borders very much apply to them.

Keep reading... Show less
Sponsored
Popular
Indigenous inhabitants of one of the floating islands in Lake Titicaca greet a tour group from Puno, Peru. David Stanley / CC BY 2.0

5 Ways Indigenous Groups Are Fighting Back Against Land Seizures

By Peter Veit

Much of the world's land is occupied and used by Indigenous Peoples and communities—about 50 percent of it, involving more than 2.5 billion people. But these groups are increasingly losing their ancestral lands—their primary source of livelihood, income and social identity.

Keep reading... Show less
Animals

Koko the Gorilla Dead at 46, an 'Icon for Interspecies Communication and Empathy'

Koko, the beloved western lowland gorilla who could communicate with sign language, died at age 46, the Gorilla Foundation announced. She died in her sleep on Tuesday morning in Woodside, California.

"Koko touched the lives of millions as an ambassador for all gorillas and an icon for interspecies communication and empathy. She was beloved and will be deeply missed," the foundation said in a press release.

Keep reading... Show less
Sponsored
Climate
West Palm Beach broadcast meteorologist Jeff Berardelli with the graphic used in Thursday's #MetsUnite campaign. Jeff Berardelli

#MetsUnite to Spread Climate Change Awareness as Heat Wave Season Begins

If you tune in to a TV weather report on today's Northern hemisphere summer solstice, you might notice the meteorologist wearing a unique striped tie or necklace that begins in blue and changes to red.

This isn't just a fun summer style. The design is actually University of Reading climate scientist Ed Hawkin's "Warming Stripes" visualization, which represents the change in annual global temperatures from 1850 to 2017. Nearly 100 TV meteorologists are displaying it in some way on Thursday as part of Meteorologists United on Climate Change or #MetsUnite, Weather Underground reported.

Keep reading... Show less
Popular
Pexels

'Public Relations Nightmare' Toxic Chemical Report Finally Released by CDC

A report with frightening consequences for American drinking water that the Trump administration tried to suppress was finally released by the Center for Disease Control and Prevention (CDC) Wednesday, ProPublica reported.

Keep reading... Show less
Sponsored

mail-copy

The best of EcoWatch, right in your inbox. Sign up for our email newsletter!