King County officials have detected “forever chemicals” in the region’s human waste and in fertilizers made from the materials, which are spread over forests and crops, according to a recent analysis.
County officials say not to panic. They expected these results, saying levels are relatively low and they don’t believe crops grown with these fertilizers are contaminated. But their findings carry some significance.
The emerging county data — published earlier this week — comes as states across the country contend with the worsening toxic legacy of these per- and polyfluoroalkyl compounds, also known as PFAS. Farms, aquifers and broad swathes of land across the country have been contaminated by the chemicals, which are known to cause cancer and a host of other health problems. Some states have gone so far as to ban the spread of fertilizers made from human waste entirely or sue chemical manufacturers. In Washington, lawmakers are pushing for new testing requirements.
These hazardous chemicals are everywhere. They’re in the food you eat, your cookware, the clothes on your back, the furniture in your house and in the foams we have used to fight fires. These compounds are even in our rainwater.
So it stands to reason these chemicals, which don’t naturally degrade, are in your waste. In urban King County much of that waste moves from your toilet to biosolids production plants where it’s turned into fertilizer for the state’s forests and cropland.
As opposed to places in Maine or Connecticut, King County’s biosolids contain relatively low levels of PFAS, which means there aren’t many major industrial sources of the chemicals in the area, the yearlong analysis shows. More than likely, we’re all consuming them in our daily lives.
“The scary part is that you’re being exposed at home,” said Sally Brown, a research professor of environmental and forest sciences at the University of Washington.
Even if King County uses this data to look for upstream sources of the chemicals (and they might know of a few), there isn’t a whole lot they can do. Neither Washington nor the federal government has any legal limit for the compounds. There are no laws to enforce here.
Still, state lawmakers are eyeing the issue. In the last days of the legislative session, they unanimously passed a bill requiring regular PFAS testing for biosolid programs across the state, of which there are more than 100.
Meanwhile, levels are low enough to continue King County’s biosolids program and even expand the business, officials say. The strategy has multiple benefits, including cutting greenhouse gas emissions and providing high-quality and consistent nutrients for Washington crops. Risk of this food absorbing the chemicals is relatively low, Brown said.
King County’s PFAS study
A common refrain in the PFAS arena is that the more we learn about these forever chemicals, the more harmful we understand them to be.
Globally, scientists and regulators have yet to understand the full scope of the problem. States (and even King County) are suing major producers of the chemicals, companies often accused of understanding the risks but continuing to churn out the compounds anyway.
King County officials expected PFAS in their waste streams and the biosolid fertilizers they produce. Other states across the country are contending with high levels of contamination and growing concern. Maine and Connecticut even banned the use of biosolids on agricultural land.
To learn more about forever chemical levels locally, the county launched a monthly testing regimen at three treatment plants in October 2023, said Erika Kinno, the county’s policy and research supervisor.
Average waste flowing out of King County’s plants was highest at the South Treatment Plant in Renton at 73.2 parts per billion and lowest at the West Point Treatment Plant near Discovery Park at 47.3 parts per billion.
For context, one part per billion is equal to about a single drop of water in an Olympic-sized swimming pool.
These findings are comparable to levels at the California Bay Area Clean Water Agencies’ treatment plants serving the San Francisco area, said Kamuron Gurol, director of the county’s Wastewater Treatment Division.
The Renton plant averaged about 33% higher than the Bay Area’s average while the West Point Plant sat about 14% lower.
Human waste treated and turned into fertilizers showed even lower levels, an average of 27.4 parts per billion at West Point on the high end and 11.8 parts per billion at the South Plant on the low end.
While Washington doesn’t regulate these compounds in biosolids, Michigan has a series of standards, Brown said. Anything below 20 parts per billion is safe to be spread on land. Surpassing that mark (as West Point did) could trigger additional investigation and anything above 100 parts per billion shouldn’t be used, she said.
Gurol said some of the elevated PFAS levels in waste streams could come from landfills and stormwater systems leaching or carrying the chemicals into the treatment plants. This calls for additional investigation but by and large the findings are reasonable.
“I’m not saying we can declare victory,” he said. “But we have a comparatively lower level of concern in what we’re finding.”
The biggest source of the chemicals is more than likely everyday items like Teflon pans, Gore-Tex jackets, hamburger wrappers, cosmetics, furniture and more, Gurol said. Waste treatment plants don’t produce any of the chemicals, they’re only on the receiving end of whatever we dump down our drains.
Really, the best way to avoid these chemicals is to stop buying products that use them whenever possible, Gurol said.
Often that’s easier said than done.
As far as PFAS levels in the biosolids used for crops, Brown is unconcerned. Not only are these low enough levels but also they’re not spread in large enough quantities to be an issue.
Kinno said King County biosolids are only spread on the same plot once every four years at most.
Plus, Brown noted that crops like wheat, which are grown with King County’s fertilizers, don’t absorb much of the compounds at all, cutting the risk even further. She sees no reason to stop using the products.
