What do new draft guidelines for ‘forever chemicals’ mean for Australia’s drinking water?

The Australian National Health and Medical Research Council (NHMRC) has released draft guidelines for acceptable levels of per- and polyfluoroalkyl substances (PFAS) in drinking water. These chemicals, often referred to as “forever chemicals,” are resistant to degradation and can persist in the environment and accumulate in the human body. The proposed guidelines aim to reduce the maximum allowable levels of four key PFAS chemicals: PFOS, PFOA, PFHxS, and PFBS.

What are PFAS chemicals?

PFAS are a group of synthetic chemicals made of carbon-fluorine bonds, which are highly stable and resistant to heat, water, and oil. This makes them useful in industrial applications, such as firefighting foams, nonstick cookware, and water- or stain-repellent fabrics. However, their environmental persistence and tendency to accumulate in the human body have raised concerns over long-term health impacts. PFAS chemicals are fat-soluble and can remain in the body for extended periods, with half the dose of PFAS taking years to be cleared.

Potential health effects of PFAS

The health risks of PFAS are still under investigation, but some potential concerns include:

• Increased cholesterol levels, which may raise the risk of heart disease.
• Thyroid dysfunction, which can affect metabolism, growth, and development.
• Cancer: While some studies suggest a possible link between PFAS and cancer, particularly with one of the chemicals, PFOS, the evidence remains inconsistent. The International Agency for Research on Cancer (IARC) has classified PFOS as “possibly carcinogenic” but notes that the evidence is inadequate.

A 2018 review by Australia’s health panel indicated that the health risks from PFAS exposure in Australia appear to be relatively low, with no conclusive evidence linking PFAS to cancer or cardiovascular diseases.

Why the revision of guidelines?

The need to revise the PFAS guidelines stems from ongoing environmental contamination, primarily due to historical industrial use. Drinking water is not a major source of PFAS exposure in Australia, but environmental contamination from sources like contaminated dust or groundwater could lead to PFAS entering water supplies. The NHMRC’s periodic reviews of the available evidence help refine these guidelines, which were last updated in 2018.

Recent studies have raised concerns about PFAS effects on thyroid function, and the IARC’s ruling on the carcinogenic potential of PFOS has prompted further investigation into the appropriate exposure limits for drinking water.

New PFAS limits

The proposed new PFAS limits are based on animal studies and human epidemiology. The NHMRC considered what concentration of PFAS exposure had no observable effects in animals, then applied a safety margin to set human exposure limits. The proposed new limits are likely to have little impact on public health in Australia, as the majority of drinking water supplies already have PFAS levels below or undetectable by these new guidelines. For instance, WaterNSW's drinking water samples show PFOS levels between 1.2 ng/L and undetectable, which is well below the new proposed limits.

Public consultation and final guidelines

The draft guidelines are now open for public consultation, with submissions due by 22 November 2024. The final guidelines are expected to be released in April 2025. The NHMRC has noted that the guidelines may differ from those of other countries due to variations in how evidence is weighed between animal studies and human data.
In summary, while the revised guidelines will help ensure the safety of drinking water, most Australians are unlikely to see a significant change in the quality of their drinking water due to the already low levels of PFAS present in most water supplies.

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