BRIEFING AND EXPERT REACTION: NHMRC releases new draft guidelines on PFAS in drinking water for public consultation

Per- and Polyfluoroalkyl Substances (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 5 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 2000’s and the levels of PFAS detected in the Australian population has steadily dropped since then. 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. E.g. 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.

Australians can continue to feel confidence that the Australian Drinking Water Guidelines incorporate the latest and most robust science to underpin drinking water safety.
 
While drinking water safety always comes first, Australians will need to turn our minds to how we afford any necessary drinking water upgrades. In some cases, advanced water treatment processes may be needed and the cost of these advances will necessarily flow through to customer bills. Drinking water cost increases will hit smaller regional communities hardest.
 
A great injustice is that this is the opposite of the ‘polluter pays’ principle, in which the clean-up cost would come from the companies and industries that caused the pollution. Passing remediation costs to drinking water suppliers, and therefore on to their customers, is an example of privatising the profits and socialising the costs.

In a nutshell, my advice is: we are fortunate in Australia in that we have hardly any water that is affected by PFAS, and you 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, e.g. 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.

You have nothing to be concerned about with PFAS in your public drinking supply unless you are specifically advised otherwise. 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.

If there is reason to suspect drinking water is contaminated you will be advised via the media, text messages, water utility websites, social media, and notices on leaflets and your water bills. You don’t need to change your drinking water habits as a result of PFAS or of the latest guidelines.

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.

So, repeating - unless you are advised otherwise by the water utility, there is no reason to be at all concerned, and no value in using alternative water sources, such as bottled water, household water treatment systems, benchtop water filters, local rainwater tanks or bores. If you still have any concerns, contact your water supplier’s customer services advice line, and review the NHMRC and similar information.

The draft outlines a detailed protocol, covering the introduction, PFAS levels in Australian drinking water, treatment methodologies, potential health effects, and the established Health-Based Guidance Values (HBGVs) for prevalent PFAS.

It addresses key PFAS compounds such as PFOA, PFOS, PFHxS, and PFBS, noting that no HBGV has been set for GenX [the next generation of PFAS chemicals]. This framework supports the assessment and management of PFAS risks in drinking water.

The data have been thoroughly extracted from reliable health-based epidemiological studies, animal research, carcinogenicity studies, and existing guidelines. Factors such as exposure timeframe, critical human health endpoints, and levels of PFAS in drinking water that cause adverse health effects were considered.

The assessment also reviewed key adverse health outcomes, including liver toxicity, immune system impacts, and developmental effects associated with long-term PFAS exposure. The HBGVs are well-justified, carefully considering the uncertainties involved, including variability in individual responses, data limitations, and challenges in translating animal study findings to human health.

This ensures that the guidelines reflect a strong commitment to safeguarding public health, accounting for the complexities and uncertainties within the available data.

The Australian government proposes updating their drinking water guideline suggesting an acceptable level of:

• 200 ng/L for perfluorooctanoic acid (PFOA)
• 4 ng/L for perfluorooctane sulfonic acid (PFOS)
• 30 ng/L for perfluorohexane sulfonic acid (PFHxS)
• 1000 ng/L for perfluorobutane sulfonic acid (PFBS)

Per- and polyfluoroalkyl substances (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 (e.g., 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. 
 
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) (i.e., 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 (i.e., not just those listed in the updated guidance),
• Improve our understanding of the environmental fate of PFAS
• Develop cost-effective PFAS drinking water technologies.  Current work is underway at UNSW to develop new technologies to clean up contaminated water

What the NHMRC has released are proposed guideline concentrations for four PFAS in drinking water for public consultation. A fifth compound (GenX) was assessed but no guideline was proposed. There are no major changes to existing guidelines except that a value for PFBS is proposed for the first time, and the limit for PFOS has been lowered from 70 ng/L to 4 ng/L (which I think is overcautious and seems to be based on only one study). The guidelines won’t be final until the public consultation is complete, and the guidelines are adopted by the states and territories.

These guidelines are not based on new research but on analysis of the extensive existing data on the topic. This a trickier task than it sounds, as a lot of the data in the literature is not suitable to base judgements about human health on.

The proposed guidelines are pretty sensible and within the ranges suggested by other regulatory agencies around the world, except for the USA - whose guidelines for some compounds are lower but based more on policy, not any scientific evidence of harm, and aren’t due to come into effect until 2029.

So what are PFAS, and why do we worry about them?

PFAS are a family of synthetic chemicals based on carbon-fluorine bonds that are used in a vast range of applications. They are often termed 'forever chemicals' because they are very resistant to degradation; the name is also a small chemistry joke, as the F in forever and C in chemicals can also stand for Fluorine and Carbon, respectively. Unfortunately, the term is misleading as it implies that PFAS never break down and that if they get in your body, they are there forever - neither of which is true.

Much public concern about PFAS comes from emotive films like Dark Waters and documentaries like How to Poison a Planet. However, emotion is not science. Neither are clicks and likes or online influencers. Science is based on testable hypotheses, good data, and evidence-based assessment. What the NHMRC (or rather their consultants) have done here is a mostly good application of these principles. I don’t think they needed to assume an industry-funded study on GenX was biased just because it was funded by industry, for example. Neither do I think basing the PFOS standard on essentially one study is the best approach.

I am sure some will assume that the guidelines have been influenced by “big chemical”, but remember that the people who set the guidelines also have to drink the water, as do their families. It’s not logical to assume they would set levels they thought were unsafe. We should also remember that the mere presence of something does not mean it will automatically cause harm under normal circumstances. The dose makes the poison, everything is toxic at the right amount, even water. For example, we know you can get skin cancer from too much sun, but that doesn’t mean you will get cancer as soon as you step outside.

The limits proposed by the NHRMC are in the nanogram per litre range. One nanogram per litre is 1 part per trillion. This is equivalent to 1 second in 31.7 thousand years. So, this is an incredibly small amount, and the risk of PFAS exposure at this level is also incredibly small.

While some PFAS have been linked to health effects, the concentrations needed to cause such effects are much, much higher than the levels typically found in Australian drinking waters. In addition to that, we aren’t sure if the major source of PFAS exposure to most people is water.  If this is the case, spending millions to go from an incredibly small amount to an even smaller amount would not be money well spent and would not improve health outcomes.

I think the NHMRC have done a pretty good job here, though I think the 4ng/L limit for PFOS is lower than it needs to be, but if people don’t agree, I’d encourage them to provide feedback and make their case to the NHMRC as part of the consultation.