Read the full article by Anna Reade & Cyndi Roper (NRDC)
“Michigan is proposing some of the most health-protective standards in the nation for several per- and polyfluoroalkyl substances (PFAS), a group of chemicals of great environmental and health concern—yet could be missing out on the opportunity to protect its citizens in the long-term.
Michigan has performed the most comprehensive PFAS monitoring in the nation, and the state has begun taking steps to protect it citizens from the health risk these dangerous ‘forever’ chemicals pose. Among the monitoring results, it was discovered that over 100 of their public water systems are contaminated with PFAS—affecting approximately 1.5 million of its citizens.
The state has also set an expedited timeline for developing and adopting drinking water standards for PFAS. To inform this process NRDC filed an filed an extensive scientific report in April of this year making a detailed case for Michigan to establish strict drinking water standards for well-studied individual PFAS and a treatment technique for the class as a whole.
Yesterday an important step in this process was made when Michigan’s independent Science Advisory Workgroup recommended health-based drinking water values which will be used by Michigan’s Department of Environment, Great Lakes, and Energy (EGLE) to develop and adopt drinking water standards by April 2020.
The Workgroup recommended health-based values for seven PFAS, listed below:
- PFNA – 6 parts per trillion (ppt)
- PFOA – 8 ppt
- PFOS – 16 ppt
- PFHxS – 51 ppt
- GenX – 370 ppt
- PFBS – 420 ppt
- PFHxA – 400,000 ppt
Two of these, PFNA and PFOA, if adopted would be the most protective in the nation. This is due to certain more health protective choices made by the Workgroup, including the use of drinking water exposure assumptions based on fetuses, infants and children—to better protect the most vulnerable groups to PFAS exposure.
Interestingly, just today New Hampshire released its final proposed standards for four PFAS, which are significantly more protective than its original proposal due to similar accounting for the unique exposures experienced by fetuses, infants and children…
It is noteworthy that although the Workgroup recommended the most protective level in the nation for PFOA, it did not base its health-based value on the most sensitive endpoint (the health effect that occurs at the lowest exposure) for PFOA. Disruption of mammary gland development is a well-established health effect for PFOA, which occurs at extremely low levels of exposure. A health-based value that is protective of this health effect would be below 1 ppt. Unfortunately, the Workgroup determined this health effect ‘may not be adverse’—yet experts have determined that developmental disruptions like this can have long-lasting adverse health effects later in life. Supporting this conclusion, three human studies (here, here, and here) have associated PFOA with decreased duration of breastfeeding.
Unfortunately, some of the other health-based values recommended by the Workgroup are not health-protective because they do not adequately address the level of uncertainty in assessing the risk these chemicals can cause. For example, there is significantly less data on how GenX and PFBS are processed by our bodies and the health effects they may cause than PFOA, yet they all have the same total uncertainty assigned to them.
Perhaps most important is the focus on individual PFAS chemicals and a lack of an assessment of or accounting for the chemical similarities among the PFAS analyzed and for PFAS in general.
Moving beyond individual chemical-by-chemical assessment is critical to properly addressing the unique contamination crisis presented by PFAS for several reasons:
- There are thousands of chemicals within the PFAS class—which is characterized by extreme persistence, high mobility in the environment, and is associated with a multitude of different types of toxicity at very low levels of exposure
- Exposures to PFAS most often occur in mixtures—multiple PFAS are found in drinking water, food, dust, personal care products, and in people’s bodies.
- Due to chemical similarities amongst PFAS, individual PFAS often target many of the same biological systems within our bodies—simultaneous exposures to multiple PFAS likely have additive or synergistic effects.
- Traditional risk assessments that assume exposures to a chemical occur in isolation could be significantly underestimating the real-world effects of PFAS exposure.
Additionally, regulating PFAS on an individual chemical basis will result in a ‘whack a mole’ problem whereby dangerous PFAS are swiftly replaced by one another and regulatory action fails to keep pace.
The Workgroup took a smart approach to address other PFAS for which we have less data by setting a screening level for these chemicals based on well-studied related PFAS for which they could set a health-based value for. The Workgroup set the screening level for these PFAS at the most protective health-based value they derived (6 ppt) because as they note,
‘these compounds are expected to produce similar health effects.’
However, the Workgroup did not set a combined health-based value for any of the seven PFAS they assessed. This approach has been taken by other states, like Vermont that has a drinking water standard for the sum of 5 PFAS at 20 ppt. Even the EPA’s health advisory is 70 ppt for PFOA and PFOS combined. An alternative approach to addressing PFAS would be to set a treatment technique that is most effective at cleaning up all known PFAS from drinking water, such as reverse osmosis…”