The work on new limit values of PFAS for drinking water in the USA has been going on for a number of years. In April 2024, the US EPA published the final National Primary Drinking Water Regulation (NPDWR) for PFAS. The regulation covers six individual PFAS compounds: PFOA, PFOS, PFHxS, PFNA, GenX (HFPO-DA), and PFBS.
- For PFOA and PFOS, the US EPA is setting a Maximum Contaminant Level Goal (MCLG), a non-enforceable health-based goal, at zero. This reflects the latest studies showing that there is no level of exposure to these contaminants without risk of health impacts, including certain cancers.
- US EPA is setting enforceable Maximum Contaminant Levels (MCL) at 4.0 parts per trillion (ppt, ng/L) for PFOA and PFOS, individually. This standard will reduce exposure from these PFAS in drinking water to the lowest levels that are currently able to be analysed and thus feasible for effective implementation.
- For PFNA, PFHxS, and “GenX Chemicals,” EPA is setting the MCLGs and MCLs at 10 parts per trillion (ng/L).
- Because PFAS can often be found together in mixtures, and research shows these mixtures may have combined health impacts, the US EPA is also setting a limit for any mixture of two or more of the following PFAS: PFNA, PFHxS, PFBS, and “GenX Chemicals”.
There are legally binding Maximum Contaminant Levels (MCL) for five of the six compounds and a Hazard Index (HI) for four (see table below). The HI calculation is based on the summation of the relative numbers obtained by division of the measured level by the health-based water concentration for the substance. These health-based concentrations are the same as the MCL for all but PFBS. The resulting sum should not exceed 1. In addition, there are Maximum Contaminant Level Goals (MCLG), a non-enforceable health-based goal, that are zero for PFOS and PFOA and the same as the MCL for the rest.
Eurofins Environment Testing performs a PFAS in drinking water suite that follows the US EPA Methods 537.1, 533, and 1633. We are able to calculate the HI to assess your water supply against these US EPA MCLs if this is required.
Table 1: Overview US EPA National Primary Drinking Water Regulation (April 2024)
| CHEMICAL | MAXIMUM CONTAMINANT LEVEL GOAL (MCLG) | MAXIMUM CONTAMINANT LEVEL (MCL) |
|---|---|---|
| PFOA | 0 | 4.0 ppt (ng/L) |
| PFOS | 0 | 4.0 ppt (ng/L) |
| PFNA | 10 ppt (ng/L) | 10 ppt (ng/L) |
| PFHxS | 10 ppt (ng/L) | 10 ppt (ng/L) |
| HFPO-DA (GenX chemicals) | 10 ppt (ng/L) | 10 ppt (ng/L) |
| Mixture of two or more: PFNA, PFHxS, HFPO-DA, and PFBS | Hazard Index of 1 | Hazard Index of 1 |
Maximum Contaminant Level Goal (MCLG): The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety and are non-enforceable public health goals.
Maximum Contaminant Level (MCL): The highest level of a contaminant that is allowed in drinking water. MCLs are set as close to MCLGs as feasible using the best available treatment technology and considering cost. MCLs are enforceable standards.
Hazard Index (HI): The Hazard Index is a long-established approach that EPA regularly uses to understand health risks from a chemical mixture (i.e., exposure to multiple chemicals). The HI is made up of a sum of fractions. Each fraction compares the level of each PFAS measured in the water to the health-based water concentration.
Regarding implementation, the crucial role of public water suppliers comes into play. Initial monitoring, a significant step, should be completed by 2027. After that, the monitoring becomes compulsory, and public information on the concentrations should be made available. In 2029, if the drinking water exceeds the MCLs, action needs to be taken by the provider and the consumers notified. The cost of monitoring and treatment technologies has been estimated to be $1.5 billion USD per year by the US EPA.
If the new US EPA limits are compared to the Australian drinking water regulations, it can be noted that only PFOS + PFHxS & PFOA are regulated, whereby the sum of PFOS + PFHxS is 70 ng/L and 560 ng/L for PFOA.
GenX (or HFPO-DA) is a PFAS that has replaced PFOA in fluoropolymer production. In the US, the compound has been the major contaminant in the Cape Fear River (North Carolina) case, while in the EU, it has been associated with emissions from the Chemours plant in Dordrecht, the Netherlands (NL). The MCL for GenX (10 ppt, ng/L) is lower than earlier estimates in both NL and US, but coincides with the Dutch guideline value for surface water from 2022 (RIVM).
Contact Eurofins PFAS experts!
Questions about PFAS can be answered by our Technical Team at EnviroTechnical@eurofins.com
About Eurofins
Eurofins Scientific through its subsidiaries is a world leader in food, environment, pharmaceutical and cosmetic product testing, discovery pharmacology, forensics, advanced material sciences, and in agroscience Contract Research services. It is also one of the global independent market leaders in genomics and in the support of clinical studies, as well as in BioPharma Contract Development and Manufacturing. In addition, Eurofins is one of the key emerging players in specialty esoteric and molecular clinical diagnostic testing in Europe and the USA. With ca. 62,000 staff across a network of over 1,000 independent companies in 62 countries and operating over 900 laboratories, Eurofins offers a portfolio of over 200,000 analytical methods for evaluating the safety, identity, composition, authenticity, origin and purity of biological substances and products, as well as for innovative clinical diagnostics. The objective of Eurofins companies is to provide their customers with high-quality services, accurate results on time and expert advice by their highly qualified staff.