A newly published peer-reviewed study is drawing national attention after researchers reported detecting measurable anti-progesterone activity consistent with the abortion drug mifepristone in municipal drinking water samples collected from three American cities.

The study, titled “Anti-Progesterone in Environmental Water,” was authored by Elise Rose, Ph.D., and Michael Varveris, M.D., and published in the July 20, 2026 edition of Issues in Law & Medicine.

Researchers collected water samples from multiple locations in Austin, Texas; Blacksburg, Virginia; and Carbondale, Illinois. Samples were taken both upstream and downstream of wastewater treatment facilities, as well as directly from municipal tap water systems serving residents.

According to the study, researchers detected significant anti-progesterone activity in eight of the nine sampling categories, with reported concentrations reaching 0.041 micrograms per liter (41 parts per trillion).

What Is Mifepristone?

Mifepristone is a prescription medication approved by the U.S. Food and Drug Administration (FDA) for use in medication abortions during early pregnancy. It is also prescribed for certain other medical conditions under specific circumstances.

The drug works by blocking progesterone, a naturally occurring hormone essential for maintaining pregnancy. Without sufficient progesterone activity, the uterine lining begins to break down, preventing a pregnancy from continuing. Mifepristone is typically followed by a second medication, misoprostol, which causes the uterus to contract and expel its contents.

Because of this mechanism, mifepristone is classified as an anti-progesterone or progesterone receptor antagonist.

What Did Researchers Find?

The study concluded that conventional wastewater treatment processes did not consistently remove the detected anti-progesterone compound from the water supply.

In some instances, researchers reported that concentrations measured downstream of wastewater treatment plants were higher than those measured upstream, raising additional questions about how pharmaceutical compounds move through municipal water systems and whether current treatment methods adequately remove them.

The reported concentrations were measured in parts per trillion, an extremely small unit of measurement commonly used for environmental contaminants.

While these concentrations are very low, the authors argue that hormones and hormone-blocking compounds may warrant additional study because biological systems can respond to very small amounts of certain substances.

Why This Matters

The study adds to a broader scientific discussion regarding pharmaceutical contaminants in the environment.

Over the past two decades, researchers around the world have documented the presence of numerous medications in rivers, lakes, groundwater, and treated drinking water, including:

• Antibiotics

• Antidepressants

• Blood pressure medications

• Pain relievers

• Birth control hormones such as ethinyl estradiol

• Anti-inflammatory drugs

• Other endocrine-disrupting compounds

  
  

Many of these substances enter wastewater systems after being excreted by patients or improperly disposed of through sinks and toilets. Conventional wastewater treatment facilities were generally not designed to remove every pharmaceutical compound now entering municipal water systems.

The authors of the new study argue that anti-progesterone compounds should be included among the pharmaceuticals receiving additional environmental monitoring and research.

Questions Remain

Although the study underwent peer review, additional independent research will likely be needed to confirm the findings, determine whether similar results are present in other municipalities, and better understand any potential public health implications.

At this time, the study does not conclude that the reported concentrations are causing documented health effects in humans. Instead, the findings raise questions about the effectiveness of existing water treatment technologies and whether additional monitoring of pharmaceutical contaminants is warranted.

As with many emerging areas of environmental research, scientists will likely continue evaluating these findings through additional testing and independent replication.

Editorial Note: IRC Media will continue following this story as additional scientific analysis, independent research, and responses from public health agencies become available.

Disclaimer: IRC Media uses aggregated public records, publicly available research, and verified sources in the preparation of its reporting. Every effort is made to ensure accuracy at the time of publication. As scientific understanding evolves, information may be updated to reflect new evidence.