PFAS in Biosolids (“sludge”) and Residuals
NEW! Maine Farm PFAS Concern - Information Update - March 26, 2019
enhances soil health
sequesters carbon (mitigating climate change)
reduces fertilizer & pesticide use
strengthens farm economies (thousands of farmers choose to use biosolids, because they work)
restores vitality to degraded lands
puts to productive use residuals that every community has to manage.
(Wastewater treatment is a vital public health service, and it creates residual solids that have to be managed!)
Sustainability & healthy soils require recycling organic residuals. Explore our website to see why.
PFAS are in biosolids, paper mill residuals, digestates, composts, & soils.
Of course they are, in trace amounts. Because these materials reflect the chemistry of our daily lives. PFAS are a family of chemical compounds commonly used in many different products we encounter in our daily lives, which is how we are exposed to them and how they end up in trace amounts (parts per billion or less) in wastewater and biosolids and other residuals. Fortunately, PFOA and PFOS, the most concerning and most-researched PFAS, have been mostly phased out, reducing potential risk. Such source reduction is the most efficient action to reduce risk - and it reduces potential concerns related to PFAS in recycled biosolids and residuals.
General information about PFAS:
NEW! EPA’s PFAS Action Plan (Feb. 14, 2019)
Interstate Council Fact Sheets
U. S. EPA PFAS webpage
U. S. CDC PFAS health info
Australian Health Expert Panel Report
Common products containing PFAS:
Textile treatments • Paper coatings • Paints • Surfactants • Pesticides • Fire-fighting foam • Floor/Ski polish • Photographic film • Denture cleaner • Mining fluids • Polymers • Non-stick cookware • Adhesives • Caulks • Lubricant additive • Carpets • Food wrappers See more.
Industry, military uses, & fire-fighting are the sources of significant PFAS contamination in the environment.
In contrast, wastewater & biosolids are part of low-level “ambient background” exposure.
The proper characterization of the known major sources of PFAS in the environment is as depicted below. Almost all of the known sites with high levels* of water and soil contamination by PFAS are directly related to:
a) industrial uses of significant volumes of PFAS with direct discharges to land or air, or
b) firefighting and fire training sites, including military sites and airports.
These are the sites that deserve and are getting the highest level of federal Department of Defense (DoD), U. S. EPA, Health Canada, and state and provincial environmental agency attention.
*”high levels” means above - and sometimes far above - EPA’s 70 ppt public health advisory level for drinking water
Wastewater and biosolids are not “sources” of PFAS.
Wastewater treatment processes do not utilize PFAS chemicals. Wastewater and biosolids convey traces of PFAS that we use and encounter in our daily lives. Only in a few worst-case scenarios have wastewater and biosolids been implicated in PFAS water contamination at levels of concern (e.g. near or above 70 ppt in water). These rare cases are where there has been ongoing discharges to the sewers from industrial facilities using significant volumes of PFAS. In these rare situations, PFAS levels in wastewater and biosolids have been reduced efficiently by investigating industries discharging to the sewer system and stopping their discharges through industrial pretreatment requirements and other source controls.
Levels compared to biosolids:
Foundation cosmetic: up to 2,370 ppb PFOA (1)
Pork liver in Taiwan: up to 283 ppb PFOA (2)
Dust in daycare center: 142 ppb PFOA median (3)
Household food waste: 6 ppb all PFAS mean (4)
U. S. human blood serum: 2 ppb PFOA mean (5)
Control garden soil: .36 ppb PFOA median (6)
NH biosolids (n = 20): 2.3 ppb PFOA mean
When biosolids are applied to soil, they are diluted ~200 times. So a typical biosolids application will result in soil levels at 0.012 ppb PFOA, for example. Compare to control (uncontaminated) garden soil, above.
(1) Danish study, Oct. 2018
(2) Chen et al., 2018
(3) Strynar and Lindstrom, 2008
(4) Brandli et al., 2006
(5) NHANES, 2012
(6) MN Dept. of Health, 2005
What is a part per trillion (ppt)?
PFAS in drinking water and other waters is usually reported in ppts.
1 ppt = 1 second in ~31,700 years
1 ppt = 1 drop of water in 20 Olympic-sized pools
(assuming ~590 drops / oz. and ~660,000 gallons in an Olympic-sized swimming pool)
1 ppt = 1 drop of water in a pool of water the size of a football field and 30.7 feet deep.
(a U. S. football field is 160 x 360 feet)
What is a part per billion (ppb)?
A ppb is 1000 times more than a ppt. It is 1 second in 31.7 years. PFAS in soils, sediments, biosolids, and residuals are usually reported in ppbs.
PFAS in our daily lives:
PFAS exposure from biosolids/residuals is unlikely & minimal.
Risk assessments by states (ME, NH, NY, VT, etc.) have determined that direct contact, inhalation, or ingestion of typical biosolids and other recycled residuals pose no significant health risk, including from the traces of PFAS they contain. Typical levels of PFAS in modern residuals are ~10 times less than the most stringent direct contact standard for soils, which is 300 ppb (ME, VT). And, when biosolids/ residuals are applied to soils, they are diluted (typically 200 times), further reducing potential exposure.
Can PFAS leach from soils amended with biosolids & residuals and affect ground- & surface water?
This is the one concern that has been raised regarding PFAS in biosolids and residuals. Limited research shows this is a possibility. But that research and investigations by state regulators indicate that typical biosolids with no direct large industrial inputs are unlikely to impact ground- and surface waters at levels above U. S. EPA’s health advisory level for drinking water (70 ppt). Therefore, the PFAS conveyed in modern wastewater, biosolids, and residuals are similar to numerous other incidental, minor releases of PFAS to the environment and are no greater risk to public health than those other releases from daily activities. (See all the ways we use PFAS.)
What can be done?
Steps we are taking to reduce potential risk
Wastewater treatment facilities and biosolids managers - who serve public health 24/7/365 - are taking proactive measures to address potential risks from PFAS in wastewater, biosolids, and residuals.
We are proactively advancing further research on the one important concern - the potential leaching of PFAS into ground- and/or surface waters.
In the meantime, we have published Interim Best Management Practices (January 2019).
The most significant action we can all take is to support removal from commerce of chemicals of high concern. That reduces the potential concerns related to wastewater, biosolids, and residuals.
We support source reduction and pollution prevention in the case of the most concerning PFAS, just as we have with regards to other trace chemicals of high concern in the past.
You can help: think about what you buy and what you use.