WHO's Proposed Limits on PFAS in Drinking Water Far Too Weak: Experts

The World Health Organization's draft drinking water guidelines for two "forever chemicals" reveal a "striking and inappropriate disregard of the best available science" and must be "extensively revised" to adequately protect public health.

So wrote former U.S. government scientists Betsy Southerland and Linda Birnbaum in an article published Wednesday in the peer-reviewed journal Environmental Science & Technology.

The stakes are extremely high, according to Southerland, the former director of science and technology at the U.S. Environmental Protection Agency's (EPA) Office of Water, and Birnbaum, the former director of the National Institute of Environmental Health Sciences.

That's because once finalized, the WHO's regulatory framework for per- and polyfluoroalkyl substances (PFAS) in drinking water is likely to be adopted by many countries. The United Nations agency's draft guidelines are much weaker than rules imposed in Denmark and advanced in Canada, and they could facilitate legal challenges to the U.S. EPA's proposed standards, which are much more stringent albeit still insufficient according to many public health advocates.

PFAS are a class of hazardous synthetic compounds widely called "forever chemicals" because they persist in people's bodies and the environment for years on end. Scientists have linked long-term PFAS exposure to numerous adverse health outcomes, including cancer, reproductive and developmental harms, immune system damage, and other negative effects. The substances—used in dozens of everyday household products, including ostensibly "green" and "nontoxic" children's items, as well as firefighting foam—have been detected in the blood of 97% of Americans and in 100% of breast milk samples.

The WHO's draft guidance recommends drinking water limits of 100 parts per trillion (ppt) individually for perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA)—two of the most well-studied PFAS—and 500 ppt total for the 29 PFAS compounds that can be reliably measured, though this is a fraught topic. The WHO's proposed limits on PFOS and PFOA are 25 times higher than those put forth last month by the U.S. EPA, and such a significant gap could hinder federal and state efforts to better regulate the nation's drinking water.

What accounts for the glaring discrepancy between the two agencies? According to the new article, the WHO has proposed relatively weak PFAS limits because its working group contends that "there is significant uncertainty and lack of consensus on whether PFOA and PFOS can be linked to adverse health effects."

Southerland and Birnbaum condemned the WHO's conclusion as "a striking and inappropriate disregard for the best available science." As the authors noted, numerous studies "link exposure to PFOA, PFOS, and other PFAS with multiple health effects, including immune effects, increased cholesterol, liver, and thyroid problems, reproductive and developmental harm, and multiple types of cancer."

In addition to failing to "take into account the overwhelming global scientific evidence of serious health effects in epidemiological studies," the WHO's guidelines "misrepresent the effectiveness of affordable, readily available treatment technology," Southerland and Birnbaum argued. "At the same time that the European Chemicals Agency is considering restrictions on the manufacture and use of all PFAS on the basis of the scientific evidence, it is stunning that the WHO maintains no health-based guidance values can be developed. To support the work of public health agencies worldwide providing people with safe drinking water, the WHO guidance levels need to be extensively revised."

The new article comes almost six months after more than 100 scientists sent a letter calling on the WHO to completely overhaul or withdraw its draft guidance and to disclose authorship and potential conflicts of interest.

In response to that letter and other demands for transparency, the WHO published a list of contributors in January. However, it remains unclear if the list is comprehensive.

Moreover, the WHO has not yet disclosed the feedback it received during the public comment period, nor has the agency announced when it plans to finalize its proposed rules.

"It is critically important for the safety of drinking water worldwide," wrote Southerland and Birnbaum, "that WHO recommendations are based on the best available science on the health effects of PFAS and the effectiveness of drinking water treatment technology."