A newly published study has detected measurable anti-progesterone activity in water samples collected in three U.S. cities, including municipal tap water. The researchers say the findings warrant additional testing to determine whether mifepristone, the abortion drug that blocks progesterone receptors, is entering drinking-water supplies and whether conventional treatment removes it.
The findings do not, however, establish that Americans nationwide are drinking mifepristone, nor do they establish that trace amounts found in the tested water cause infertility or other health problems in humans.
The study tested three communities and used a biological assay that measures anti-progesterone activity expressed as “mifepristone equivalents,” meaning additional chemical testing is needed to identify precisely which compounds produced the results.
What the Study Actually Found
The study, titled “Anti-Progesterone in Environmental Water,” was published July 20 in Issues in Law & Medicine. Researchers Elise Rose, Ph.D., and Michael Varveris, M.D., collected water samples from three communities: Austin, Texas; Blacksburg, Virginia; and Carbondale, Illinois.
Samples were taken upstream and downstream of wastewater-treatment facilities and from municipal taps. Reports on the study say researchers found statistically significant anti-progesterone activity in eight of nine sampling categories, with the highest reported measurement equivalent to approximately 41 parts per trillion of mifepristone.
The researchers used a PR-CALUX biological assay to measure anti-progesterone activity. That distinction is important: the test does not, by itself, prove that every detected molecule was mifepristone. Rather, the results were converted into mifepristone-equivalent concentrations based on the activity of the reference compound.
The study’s authors concluded that the findings warrant additional investigation into the identity, sources, persistence, and potential health effects of the compounds detected.
How Could an Abortion Drug Get into Water?
Mifepristone is a progesterone receptor antagonist. The FDA says it is approved, when used with misoprostol, to terminate an intrauterine pregnancy through 70 days of gestation. The FDA first approved Mifeprex in 2000.
After a drug is taken, pharmaceutical compounds and their metabolites can be excreted from the body and enter wastewater. Unused medications can also enter the environment through improper disposal.
The possibility is not new. An FDA environmental assessment from the 1990s acknowledged potential environmental entry through patient excretion, pharmaceutical waste disposal, and manufacturing, while concluding that adverse environmental effects were not expected at the time.
What has changed is the scale of medication abortions. According to the Guttmacher Institute’s 2023 data, approximately 642,700 medication abortions occurred within the U.S. formal health care system that year, accounting for 63% of abortions. (The figure does not capture every self-managed abortion.)
Lawmakers Have Been Asking EPA to Investigate
In June 2025, Sen. James Lankford (R-OK), Rep. Josh Brecheen (R-OK), and more than 20 other Republican lawmakers asked EPA Administrator Lee Zeldin to investigate whether mifepristone and its metabolites could be entering the nation’s water system.
Lankford said in the letter the following:
“Federal regulators are rightfully eager to study the health effects of many chemicals in our water and septic systems, but they haven’t examined the environmental and public health risks of chemical abortion drugs like mifepristone in those same systems.”
The lawmakers’ request was followed by additional congressional and state-level efforts in 2026. In June, 19 Republican members of Congress asked EPA to consider mifepristone for its sixth Contaminant Candidate List, which is used to identify substances that may warrant further evaluation under the Safe Drinking Water Act.
EPA has since said it is reviewing comments concerning pharmaceuticals in drinking water. The agency’s 2026 pharmaceutical benchmark program covers 374 FDA-approved pharmaceuticals that may occur in source or treated drinking water. The benchmarks themselves are not drinking-water regulations.
What are the Potential Health Risks?
This is where the evidence becomes considerably less certain.
Mifepristone is pharmacologically active because it blocks progesterone receptors. Consequently, researchers have legitimate reasons to ask whether sustained exposure to anti-progesterone compounds could affect organisms.
Studies in aquatic species provide some evidence that mifepristone can affect reproduction. A 2013 study published in Aquatic Toxicology exposed zebrafish to low concentrations of mifepristone and reported reproductive and ovarian effects. The researchers described effects at concentrations measured in nanograms per liter.
Other research has found anti-progestogenic activity from multiple compounds in wastewater and surface water. A scientific review concluded that some progestins can affect aquatic reproduction at environmentally relevant concentrations, while also emphasizing that additional research is necessary to determine environmental risks, particularly from mixtures of compounds.
No study identified in this review has established that trace concentrations of mifepristone or mifepristone-equivalent activity in U.S. drinking water cause infertility, miscarriage, developmental problems, or other human health conditions.
Infertility is Increasing, but Causation Has Not Been Established
Infertility is a genuine and significant health issue. The World Health Organization estimates that about one in six people worldwide experience infertility during their lifetime. Causes can involve male factors, female factors, both partners, or remain unexplained.
But that statistic cannot be used to establish a connection to mifepristone in drinking water.
The WHO identifies numerous potential contributors to infertility, while the CDC’s latest fertility-services data show that 13.7% of U.S. women ages 20–49 had used some form of fertility service in 2022–2023.
There is currently no epidemiological evidence demonstrating that environmental mifepristone exposure is responsible for a measurable portion of infertility in the United States.
The Biggest Unanswered Question: What Exactly is in the Water?
The new study provides an important distinction between detecting biological activity and identifying a specific chemical.
Because the assay measures anti-progesterone activity, other substances could potentially contribute to the result. Researchers would need to use targeted analytical chemistry, such as liquid chromatography coupled with mass spectrometry, to determine whether mifepristone itself, its metabolites, or other compounds are responsible.
Researchers also need substantially larger sampling efforts across different regions, seasons, wastewater systems, and drinking-water sources.
The federal government already recognizes pharmaceuticals as an emerging water-quality issue. EPA’s pharmaceutical benchmark program is designed to help communities evaluate potential exposure to drugs in source and treated drinking water.
What Could be Done?
The most immediate step would be more testing.
Testing should determine whether mifepristone itself is present, distinguish it from other anti-progesterone compounds, measure concentrations before and after treatment, and establish how frequently the compounds occur.
Treatment technology also matters. Research into pharmaceutical removal has found that conventional wastewater treatment does not necessarily eliminate every pharmaceutical compound. Advanced processes, including activated carbon, ozonation, advanced oxidation, and membrane-based treatment, can provide additional removal for some pharmaceutical contaminants, although their effectiveness varies by compound and treatment system.
For consumers, the FDA recommends using drug take-back programs for most unused medications and says medications not on its flush list generally should not be flushed.
For water utilities and regulators, however, household disposal is only one potential pathway. If mifepristone or another anti-progesterone compound is confirmed in drinking water, regulators would need to determine the concentrations, exposure levels, health benchmarks, and most effective treatment methods before concluding that the contamination presents a health risk.
Provided by Dallas Express
