Washington is one step closer to eliminating a major blind spot for potential contaminants in crops grown across the state using human waste as fertilizer.
Lawmakers voted unanimously last week to send Senate Bill 5033 to Gov. Bob Ferguson. The bill would require the state Department of Ecology to test fertilizers made from human waste for levels of toxic chemicals known as per- and polyfluoroalkyl substances, or PFAS, which cause cancer and a host of other health problems.
A representative for Ferguson did not respond to an inquiry as to whether the governor plans to sign the bill. But the measure comes with the full-throated support of the state House and Senate. Earlier versions of the proposal fizzled in the Statehouse but the version introduced this year passed both chambers with unanimous support.
Fertilizers made from human waste are common across the country, though they’re met with mixed reactions. In states like Connecticut and Maine, these fertilizer streams are so badly contaminated with PFAS — also called “forever chemicals” — that state lawmakers banned their use on agricultural lands. Elsewhere the resource is hailed as the future of the agricultural industry in the era of sustainability.
The practice also has a series of climate applications. The high-moisture content of the fertilizer can counteract worsening droughts. And using the waste reduces the carbon footprint of waste treatment plants because if the biosolids weren’t used, they’d either be dumped into a landfill or incinerated, which would generate greenhouse gases.
In Washington, experts say the PFAS problem isn’t nearly as pronounced because upstream contaminant sources, like industrial manufacturers, are relatively minimal. King and Pierce counties produce great quantities of fertilizer from human waste and the programs have been locally acclaimed for years.
Still, local operations producing fertilizer from human waste (also known as biosolids) have little data on PFAS levels within their products. King County commissioned a study on its program, called Loop, but the results aren’t yet publicly available. Washington hasn’t previously required testing for these chemicals and has yet to enact any specific limits for the compounds.
To that end, King County officials have welcomed the PFAS testing bill. The measure’s sponsor, state Sen. Jeff Wilson, R-Longview, testified earlier this year that he supports the use of biosolids but the law would aim to ensure they’re safe to use on the crops we eat.
Around 110 waste treatment facilities across the state produce biosolids allowed to be spread on farms or gardens, amounting to tens of thousands of tons of the material every year.
If Ferguson signs the bill, it would require Ecology to establish PFAS sampling and testing requirements for biosolids by July 2026. Facilities producing the biosolids must begin quarterly testing by the start of 2027 and turn their results into Ecology by late 2028. Then, in 2029, the state department will report its analysis back to the Legislature with recommendations on how to move forward.
