New health-based guidelines for PFAS in drinking water

The National Health and Medical Research Council (NHMRC) has released updated draft guidelines for per- and polyfluoroalkyl substances (PFAS) in drinking water.

The new draft guidelines include revised guidance on regulations for four main PFAS chemicals which will inform state and territory strategies for maintaining water supply safety. These chemicals include: perfluorooctane sulfonic acid (PFOS); perfluorooctanoic acid (PFOA); perfluorohexane sulfonic acid (PFHxS); and perfluorobutane sulfonic acid (PFBS).

The draft guidance also includes additional information on hexafluoropropylene oxide dimer acid and its ammonium salt (GenX chemicals).

The health-based guideline values are conservative, protective of human health, and are based on comprehensive evaluations of the latest evidence.

Submissions on the draft guidance will close Friday, 22 November 2024.

The Water Quality Advisory Committee in consultation with NHMRC will consider all submissions. Therefore, it must not be assumed that these PFAS guideline values will be the final ones for the Australian Drinking Water Guidelines, after public consultation is taken into account, said the NHMRC in a statement.

The final guidance material will be published as part of the Australian Drinking Water Guidelines in April 2025. Until then, the current guidelines remain in effect.

Limited health impacts?

Dr Ian Musgrave, a Senior Lecturer in the Faculty of Medicine, School of Medicine Sciences, within the Discipline of Pharmacology at the University of Adelaide, said PFASs are highly fat soluble compounds that are very slow to break down. They persist in the environment and can accumulate in the human body.

“It can take five years for half an ingested dose of PFAS to be removed. Because they have the potential to mimic the body’s own fats there was concern PFAS could have adverse health effects if sufficient amounts accumulated in the body. PFAS began to be phased out in Australia in the 2000s and the levels of PFAS detected in the Australian population has steadily dropped since then,” Musgrave said.

“Now that industrial use has been phased out, the main way we are exposed to PFAS is through things like persistent environmental contamination including drinking water from contaminated environmental sources.

“The Australian drinking water guidelines provide limits for how much PFAS is allowed to be in our drinking water. The NHMRC periodically reviews the health evidence around PFAS used to develop these guidelines, which were last updated in 2018.

“The latest review looks at additional evidence available since 2018. After carefully reviewing multiple line of evidence about health impacts, and including revised estimates of how much PFAS is coming from other environmental sources and food. The limits have been revised downwards as follows:

“Current PFOS + PFHxS: 70 ng/L. New PFOS: 4 ng/L, PFHxS: 30 ng/L. Current PFOA: 560 ng/L. New PFOA: 200 ng/L.

“There are likely to be limited health impacts from this revision, as most potable water supplies in Australia either have no detectable PFAS or levels already below the new limits. Eg, drinking water sampling for NSW water found levels of PFOS from 1.2 ng/L to undetectable, PFHxS from 1.4–0.1 ng/L and PFOA to be basically undetectable.

“While the concentration of PFAS in bores near contamination sites is high, these are typically not used as drinking water sources,” Musgrave said.

More work required to map out contamination

Denis O’Carroll, a Professor in the Water Research Laboratory and Deputy Head of School (Research) in the School of Civil and Environmental Engineering at UNSW Sydney, said PFAS constitute a class of over 14,000 chemicals that have been extensively used in industrial applications and consumer products around the world and are a serious health concern.

For example, the World Health Organization lists PFOA as a Group 1 carcinogen and PFOS as a Group 2B carcinogen. International organisations (eg, European Union and the US Centers for Disease Control) have serious health concerns about a much wider range of PFAS than those subject to Australian guidelines, O’Carroll said.

“Proposed drinking water guidelines are much less stringent than those of the European Union, the United States and Canada. One of the most restrictive recommendations for drinking water is Health Canada’s, with the sum of all PFAS being less than 30 ng/L, whereas the European Union recommends the sum of all PFAS being less than 500 ng/L or the sum of 20 select PFAS being less than 100 ng/L.

“In April this year, the US EPA [Environmental Protection Agency] set drinking water concentration limits of 4 ng/L for PFOS and PFOA, 10 ng/L for PFHxS and 2000 ng/L for PFBS in their National Primary Drinking Water Regulation.

“They also set limits on PFNA and GenX, which are not subject to the new Australian guidance. A range of PFAS is also subject to the Stockholm Convention for the protection of human health and the environment from persistent organic pollutants (POPs) (ie, PFOS, PFHxS, PFOA and potentially all long-chain perfluoroalkyl carboxylic acids). The new Australian drinking water guidelines do not include all PFAS on the Stockholm Convention list.

“Our study published earlier this year in Nature Geoscience investigated the global extent of PFAS in our surface and groundwaters. We found that PFAS levels in many of our international drinking source water exceed drinking water guidance levels and that international guidance is much more stringent than Australia.

“The Australian Government should consider the inclusion of a wider range of PFAS in the drinking water guidelines as is common in a number of other countries.

“Much more work is required to map out PFAS contamination in Australian source waters, and the government urgently needs to fund research to better understand the health and ecosystem risks posed by a wide range of PFAS (ie, not just those listed in the updated guidance); improve our understanding of the environmental fate of PFAS; [and] develop cost-effective PFAS drinking water technologies. Current work is underway at UNSW to develop new technologies to clean up contaminated water,” O’Carroll said.

Active monitoring and management

Dr Daniel Deere, a Water and Health Consultant at Water Futures, said we are fortunate in Australia in that we have hardly any water that is affected by PFAS, and should only be concerned if directly advised by the authorities.

“In more detail, our concerns are largely limited to a small number of hotspots where there has been extensive use of firefighting foam in the past, eg, directly adjacent to airports or firefighting training grounds. These have been identified and the PFAS risk is well understood and being actively monitored and managed,” Deere said.

“Public water supplies in Australia are all managed by specialist professionals employed by local and state/territory government utilities, and overseen by water utility regulators and health departments.

“Remember that water utility staff and their regulators, and their friends and family, drink the same water that you do. They have no incentive or reason to provide unsafe water, or to hide information from the public.

“If levels of PFAS present a risk to your health in your water supply two things will happen. Firstly, you will be notified within at most a few days of the problem being confirmed, as required under their regulations. Secondly, and as soon as reasonably practicable and affordable, the problem will be resolved through things like changing water sources or introducing PFAS removal treatment.”

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