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contaminants

January 14, 2025

PFAS in sludge spread on farmland poses health risks, EPA report says

By Shannon Kelleher and Carey Gillam

US regulators on Tuesday added to growing concerns about the long-standing practice of using sewage sludge to fertilize farmland, releasing a report warning that chemicals contaminating the sludge pose heightened human health risks for cancer and other illnesses.

The Environmental Protection Agency (EPA) said two types of hazardous per- and polyfluoroalkyl substances (PFAS) widely found in sewage sludge, a byproduct of wastewater treatment, can contaminate the milk, eggs and meat that come from farm animals raised on agricultural land where the sludge has been applied. Those “exposure pathways” are among multiple ways in which people can be at risk, the EPA said.

The agency focused on perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), two well-studied types of PFAS chemicals linked to testicular and kidney cancer as well as liver problems. The EPA last spring designated PFOS and PFOA as hazardous substances under the so-called Superfund law and announced the first legally enforceable limits for the two chemicals and four other types of PFAS in drinking water.

The EPA said that though the majority of US food crops are not grown with the use of sewage sludge as a soil conditioner or fertilizer, because of the “extreme persistence” of PFOA and PFOS in soils, land where sewage sludge was applied years ago may still be contaminated.

The agency’s draft risk assessment, which was made publicly available Jan. 14, said that “under certain scenarios and conditions,” land-applying or disposing of sewage sludge containing 1 part per billion (ppb) or more of PFOA or PFOS “could result in human health risks exceeding the agency’s acceptable thresholds for cancer and noncancer effects.”

November 2, 2023

EPA restarts assessment of health risks from nitrate in water

By Brett Walton

The US Environmental Protection Agency, reversing a Trump-era decision, is restarting a human health assessment of nitrate and nitrite, a move that has potentially far-reaching regulatory implications for one of the country’s most pervasive drinking water contaminants.

The EPA suspended its nitrate assessment in December 2018. It was one of nine chemicals that the Trump administration deemed no longer a priority for evaluation by the agency’s health assessment division known as the Integrated Risk Information System, or IRIS.

That changed in June when the EPA quietly reinserted the nitrate assessment into the IRIS agenda “to address an agency priority.”

The decision to take a closer look at the chemical comes at a time of increased scrutiny and public concern over nitrate exposure and human health. Nitrate forms when nitrogen is exposed to oxygen in the air. An exponential increase in the use of synthetic, nitrogen-based fertilizers since 1950 supercharged the production of corn and soybeans. The number of large livestock feeding operations — and the amount of manure they produce — also increased rapidly.

Nutrients are essential to crop production. But the convergence of high rates of chemical fertilizer use and immense manure production led to well-documented risks to human health and the environment. In addition to generating heat-trapping greenhouse gases, over-application of nitrogen-rich fertilizer and manure contributed to steadily rising levels of nitrate in streams and groundwater, particularly in the 11 Corn Belt states across the Great Lakes and Midwest, California’s Central Valley, North Carolina, and Washington’s Yakima Valley.