The Environmental Protection Agency (EPA) is utilizing data from over 20 years ago to establish the nation's first drinking water standard for perchlorate, a chemical found in rocket fuel, missiles, fireworks, and military flares. This chemical can contaminate groundwater used for public drinking water systems and is undetectable by sight, smell, or taste.
A Daily Mail analysis of the EPA's 2001-2005 nationwide survey revealed perchlorate in 126 public water systems across 26 states. Since then, no equivalent nationwide survey has been conducted, leaving the current extent of contamination uncertain.
Despite the aged data, the EPA is combining it with compliance monitoring data from California (2007) and Massachusetts (2023) to estimate the number of water systems that might exceed the proposed national limit. The agency is mandated to finalize this rule by May 21, 2027.
Perchlorate's history with the EPA has seen shifting positions. The agency opposed a federal limit in 2008, citing infrequent concerning levels, but reversed course in 2011, concluding a national standard was necessary under the Safe Drinking Water Act. A lawsuit by the Natural Resources Defense Council (NRDC) in 2016 compelled the EPA to act on its missed regulatory deadline.
In 2019, the EPA identified reduced IQ in children following prenatal exposure as the most sensitive health effect of perchlorate, noting its disruption of thyroid hormone production. A human study from that year indicated that pregnant women with the highest perchlorate levels were over three times more likely to have children in the lowest IQ percentile at age three. However, in 2020, the EPA again proposed not to set a standard, citing updated analyses and state actions. The Biden administration reviewed this decision in 2022 and upheld its scientific basis. A federal appeals court ruling in 2023, however, mandated that the EPA must propose regulations, deeming the chemical a public health threat.
"Members of the public deserve to know whether there’s rocket fuel in their tap water," said NRDC senior attorney Sarah Fort, according to the Associated Press. "We’re pleased to see that, however reluctantly, EPA is moving one step closer to providing the public with that information."
Perchlorate contamination is often linked to military bases and aerospace facilities where production and testing have occurred over decades. The chemical dissolves easily in water and can travel long distances through groundwater.
Upon ingestion, perchlorate hinders the thyroid's uptake of iodine, a nutrient crucial for hormones regulating metabolism, growth, and brain development. Shan Yin, a toxicologist with the American College of Medical Toxicologists, told the Daily Mail that the thyroid is vital for neurodevelopment, making pregnant women and infants particularly at risk.
The EPA's 2019 assessment highlighted the vulnerability of developing fetuses, which depend on maternal thyroid hormones during early pregnancy when the brain and nervous system rapidly develop. Yin noted that pregnant women's increased metabolic demands while carrying a fetus could exacerbate the impact of perchlorate exposure.
While drinking water is a regulated exposure pathway, research suggests food is now the largest source of perchlorate for most Americans, with the chemical detected in nearly all produce, dairy, and packaged foods. The 2001-2005 EPA survey showed California had the highest number of affected water systems, followed by New York and Arizona.
Some water systems recorded high concentrations, including Sebring, Florida, at 70 parts per billion (ppb) and Redlands, California, at 67 ppb. These figures are from over two decades ago, and current levels are unknown.
In the absence of a federal rule, states like California and Massachusetts have implemented their own enforceable standards, at 6 ppb and 2 ppb respectively. At least ten other states have adopted health advisories or screening levels that vary significantly.
The EPA is currently considering federal limits of 20 ppb, 40 ppb, or 80 ppb, which are considerably higher than some state-level limits. The agency has stated that it anticipates fewer than one-tenth of one percent of regulated water systems will exceed the proposed limits, arguing that the majority of systems would face significant costs with limited public health benefit.
If adopted, water utilities exceeding the limits could be required to implement treatment systems, close contaminated wells, or find alternative water sources.
