Millions of dry tons of “biosolids”—the nutrient-rich waste from municipal wastewater treatment, also known as sewage sludge—are applied annually to agricultural soil in the United States as a natural alternative to petroleum-based fertilizers. However, this practice, long marketed to farmers as an environmentally friendly solution, has caused widespread contamination with PFAS substances, known in the media as “forever chemicals.”
Environmental scientist Jake Thompson from Yale University explains that the problem of PFAS contamination in agricultural land disproportionately harms small-scale and organic farmers, who used fertilizers loaded with these substances before the full scale of the issue became clear. Thompson and his research team have proposed a new detailed treatment method, published in the journal “Proceedings of the National Academy of Sciences,” which promises to reduce PFAS concentrations in soil at a much lower cost than current methods.
Alarming Numbers on the Scale of Contamination
According to a national sewage sludge survey conducted by the U.S. Environmental Protection Agency in 2001, the total annual amount of biosolids produced in the United States contains between 2,749 and 3,450 kilograms of PFAS substances, roughly half of which is applied to agricultural land, according to ScienceAlert.
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It is noted that “forever chemicals” do not break down easily, as the carbon-fluorine bond at the core of these molecules is extremely strong, allowing them to persist in the environment for thousands of years. When applied to soil, these substances gradually accumulate with each new fertilization event and can leach into waterways or be absorbed by plants growing in contaminated soil, re-entering the food chain.
Increasing Health Risks
Growing scientific evidence indicates that exposure to PFAS substances may be harmful to the health of living organisms. Laboratory and animal studies have suggested a potential role for these substances in causing cancer, as well as pregnancy and reproductive problems. Studies on human populations have also revealed links between exposure to these substances and the development of certain types of cancer, an increased risk of cardiovascular disease, multiple sclerosis, and fertility issues, although many of these studies are still in their early stages.
Thompson points out that this study, despite its focus on the United States, reflects a global challenge facing many countries based on available data.
Huge Cost Difference
The cost of removing PFAS substances from U.S. agricultural land using current methods is estimated to be between $800,000 and $1.6 million per hectare, which equates to roughly $8 trillion on a national level.
In contrast, the cost of the proposed new method is only about $29,000 per hectare, if the process is repeated for up to 20 years to ensure complete treatment.
The researchers emphasize that their method