PFAS In Sewage Sludge Is A Human Health Risk
I Hate To Say, I Told You So, But Here We Are. The Science Is In. Hopefully, Regulations Will Follow.
Yesterday, the U.S. Environmental Protection Agency released a draft risk assessment, or scientific report, on the potential human health risks associated with the presence of toxic per- and polyfluoroalkyl substances (PFAS) chemicals in biosolids, also called sewage sludge.
I have been talking about the health risks of this sludge since Day 1 of this newsletter, so to have our largest environmental agency discuss the severity of this issue is a big deal.
The EPA found that there may be human health risks associated with exposure to PFOA or PFOS also known as “forever chemicals” with all three methods of using or disposing of sewage sludge—land application of biosolids, surface disposal in landfills, or incineration.
In fact, the practice of using this sludge as fertilizer on farmland can contaminate the soil, groundwater, crops, and livestock.
It’s a messy practice and even low levels of exposure can cause damage.
For decades, EPA encouraged the use of sludge from treated wastewater as inexpensive fertilizer without limits on the amount of PFAS it might contain, and the agency still does not regulate these toxic compounds found in biosolids.
Late last year, The New York Times reported that 3M, which manufactured PFAS for decades, found as early as 2000 that these chemicals in sludge samples from municipal wastewater plants across the country. In 2003, 3M told EPA about its findings.
The model in the current risk assessment showed human health risks exceeding EPA’s acceptable thresholds, sometimes by several orders of magnitude, for some scenarios where a farmer applied biosolids containing 1 part per billion (ppb) of PFOA or PFOS (which is near the current detection limit for these PFAS in biosolids).
“This draft assessment provides important information to help inform future actions by federal and state agencies as well as steps that wastewater systems, farmers, and other stakeholders can take to protect people from PFAS exposure,” EPA Acting Administrator Jane Nishida said in a statement.
It’s worth noting that Maine became the first state ever to ban the spreading of sludge as fertilizer in 2022 to help stop the source of widespread toxic PFAS contamination. The PFAS-laced biosolids are now shipped to a state-owned landfill each day, but state regulators say if investments aren't made to manage it, the landfill could be at capacity as soon as 2028.
Both Texas and Oklahoma have introduced bills that would limit or eliminate sludge use on farmland.
What did the EPA risk assessment find?
The research focused on those living on or near impacted sites (e.g., farm families and their neighbors) or those that rely primarily on their products (e.g., food crops, animal products, drinking water).
Note: the draft risk assessment did not model risks for the general public.
EPA found that there may be human health risks exceeding the EPA’s acceptable thresholds for some modeled scenarios when land-applying sewage sludge that contains 1 ppb of PFOA or PFOS.
The report also discovered human health risks associated with drinking contaminated groundwater sourced near a surface disposal site when sewage sludge containing 1 ppb of PFOA or sewage sludge containing 4 to 5 ppb of PFOS is disposed in an unlined or clay-lined surface disposal unit.
The assessment is not an enforceable rule, but it does provide data that can inform future regulations or actions.
What are biosolids/sludge, again?
When sewage from households and businesses goes to a wastewater treatment plant, the liquids are separated from the solids and produce a nutrient-rich product known as “sewage sludge.” The EPA typically uses the term “biosolids” to refer to treated sewage sludge that is intended to be applied to land as a soil conditioner or fertilizer.
Sometimes, biosolids are distributed to farms. While some states, Tribes, or counties may have additional rules around the use of biosolids, federal rules currently allow biosolids to be applied to pastures, feed crops, and crops for direct human consumption.
Biosolids can also be applied to forests, tree farms, golf courses, turf farms, and other types of land. In other cases, biosolids are bagged and sold at stores to the general public and are often used on lawns or in home gardens.
About 60 percent of sewage sludge produced in the U.S. each year is applied to land.
Why assess risk now?
Although domestic manufacturing of PFOA and PFOS have been phased out and their uses restricted, multiple activities still result in PFOA, PFOS, and their precursors being released to wastewater treatment plants.
Traditional wastewater treatment technology does not remove or destroy PFOA or PFOS, and these chemicals typically accumulate in the sewage sludge.
PFOA and PFOS have strong chemical bonds, which means they do not break down on their own in the environment or in our bodies. The chemicals can move from soils to groundwater or nearby lakes or streams, and be taken up into fish, plants, and livestock.
These factors combine to raise questions about the potential risks associated with the presence of PFOA or PFOS in sewage sludge that is land applied as a fertilizer (on agricultural, forested, and other lands), surface disposed, or incinerated.
Current and historical activities include:
Industrial releases from certain types of firefighting foam or pulp and paper plants
Commercial releases from car washes or industrial launderers
Down-The-Drain releases from homes when using consumer products like after-market water resistant sprays, ski wax, floor finishes, and laundering of stain or water-resistant textiles with PFOA or PFOS coatings.
Studies have found that PFOA and PFOS in sewage sludge—even at treatment plants that only receive wastewater from residential and commercial users. Throughout the country, any of these release mechanisms may play a role in PFOA or PFOS entering the plant and contaminating the sewage sludge.
The EPA’s analysis did not suggest that the general food supply is impacted by the use of biosolids that contain PFOA or PFOS.
The U.S. Department of Agriculture and Food and Drug Administration monitor for PFAS in the food supply broadly.
Based on the best available data, biosolids account for less than one percent of the fertilized acreage of productive agricultural land in the U.S. per year, according to the EPA. While that number sounds low, it still accounts for millions of acres of farmland across the country.
Certain “hot spots” and specific farming operations may have higher levels of PFOA or PFOS if contaminated sludge has been applied. Further collaboration with impacted operations and other federal agencies will be important to fully understand risks and support impacted farmers.
Now that the risk to human health is becoming more clear, we need to pursue ways to limit PFAS in wastewater and sewage. Two ways are 1) to restrict PFAS use in everyday products and 2) to treat polluted wastewater before it enters treatment plants. These costs should be carried by the manufacturers of these products, who created this contamination nightmare in the first place.
The draft risk assessment document, Draft Sewage Sludge Risk Assessment for Perfluorooctanoic Acid (PFOA) and Perfluorooctane Sulfonic Acid (PFOS), will be available for public comment for 60 days following announcement in the Federal Register. Learn more about the draft risk assessment and how to comment on it.
Here are the EPA’s Regional and State Contacts for Biosolids.
Wildfires are still burning in California.
While wildfires can cause a variety of problems with water supplies that aren’t always straightforward to detect, consider all drinking water from close proximity to a wildfire to be chemically unsafe until proven otherwise. If you are on a utility, follow your utility’s guidelines as they communicate their activities around the fire.
Private wells are also at risk of damage and contamination from wildfires. You should always test your well water after any changes in water appearance, smell and/or taste.
How Can You Tell if Your Drinking Water Is Contaminated?
Foul-smelling and/or discolored water
Reduced water pressure
Broken or leaking pipes, valves, and hydrants
Heat-impacted materials in/near your plumbing system.
Want to know more about how wildfires can impact your drinking water quality? Our friends at TapScore put together this great resource.
Questions or comments on sewage sludge? Keep the conversation going in the comments below.