More than 520 chemicals found in English soil, including long-banned medical substances | Farming

More than 520 chemicals have been found in English soils, including pharmaceuticals and toxins that were banned decades ago due to the practice of spreading human waste to fertilize arable land.

Research by scientists at the University of Leeds, published as a pre-print in the Journal of Hazardous Materials, has revealed a worrying range of chemicals in English soils. Nearly half (46.4%) of the pharmaceutical substances detected had not been reported in previous global surveillance campaigns.

The anticonvulsants lamotrigine and carbamazepine were among the drugs for human use first reported on English soil.

One category of chemicals of particular concern to scientists is emerging contaminants, which are pharmaceuticals and other chemicals whose impact on the environment or human health has not been widely studied as they re-enter the food chain.

Water companies treat human feces and remove some contaminants from wastewater at their treatment centers. The resulting product is processed biosolids, organic matter derived from human waste, and these are often disposed of by being spread on fields as fertilizer.

However, it appears that despite decontamination, hundreds of chemicals leach into the soil and, in some cases, remain there for many years. Many chemicals banned or withdrawn from use decades ago persisted in agricultural soils.

One of the researchers, Laura Carter, professor of environmental chemistry at the University of Leeds, said: “Some chemicals were banned from use decades ago and their presence suggests they are truly persistent…so soils are a long-term sink for these pollutants.” »

It’s possible these chemicals could enter the food chain and be ingested by humans who eat food grown in these fields, she said. It could also harm agricultural productivity if chemicals inhibit plant growth or harm soil health.

“Some of the work we did before this monitoring campaign focused on uptake and accumulation in crops and effects on soil and plant health,” she said. “What we need to understand is the subsequent pathway from cultivation to consumption. Some of these contaminants can [affect] soil health and inhibit nutrient uptake by crops.

To conduct the research, Carter and his team asked farmers to send soil samples to their lab and also visited some farms themselves. They took various steps to detect what she calls a “chemical fingerprint” of the soil, using methods such as mass spectrometry.

The EU is working to eliminate these emerging contaminants from wastewater across the continent by passing legislation requiring countries to implement “quaternary treatment,” which is an advanced pollution removal method capable of removing micropollutants such as these chemicals. The UK has no plans to do this and is currently relying on less precise tertiary treatment systems.

“Wastewater treatment processes can remove some contaminants,” Carter said. “We found that the processes are not as effective as they should be in removing them.

“These chemicals are unregulated, so there is no desire to develop or focus on technologies that can eliminate them. More advanced treatment, such as the quaternary treatment planned by the EU, will generally eliminate more of them.”

Soil pollution is understudied compared to wastewater and river research, despite the fact that soils are so important to human and environmental health and contaminants can persist for decades.

“It’s due to a combination of factors. There are analytical challenges, the chemicals are often in trace amounts so you have to develop methods to extract them; the soil and biosolids and more agricultural focus mean you have to deal with the complexity of environmental measurements when you’re trying to monitor them. And there’s a lack of awareness about the pathways by which they enter the environment,” Carter said.

Contaminants can be removed, she said: “You can do processes like actively planting crops so that they absorb the contaminants and that’s one way to remove the contaminants from the soil. But then you’ll have to try to get rid of that contaminated plant.”

She was very surprised to discover the banned chemicals, as it showed the long-term persistence of contaminants in the soil. “Their use has been banned for several years, so we were surprised by their persistence in soils,” Carter said.

“We were also able to detect some anti-cancer drugs, which was surprising because there isn’t a lot of research in this area so we haven’t seen those detected before.”

It’s not the farmers’ fault for spreading this, she said, because that’s what they’ve been told to do to be sustainable.

“We need to regulate them properly and we need education to make sure everyone knows what’s being enforced and what the potential risks are associated with it,” Carter said.