Human sewage sold as a cheap form of fertiliser to British farms contains microplastics that could harm agricultural land, according to a confidential report prepared for the Environment Agency and seen by the Telegraph.
The majority of British wastewater is repurposed into 3.6m tonnes of treated sludge supplied by water companies and used on farmlands every year, on 370 sites across the country.
The practice has boomed in the last 20 years, after the government banned water companies from dumping sewage at sea in 1998 because of the threat to marine life.
But the report says the composition of waste has changed significantly since regulations were first brought in and microplastics are a growing concern.
The report, leaked to Greenpeace’s Unearthed team, was prepared in 2017 but the Environment Agency is yet to act to update regulations.
It warns microplastics could harm soil ecosystems or crops either directly or through hormone-disrupting substances, and contain chemicals that could be released slowly as they break down over hundreds of years.
Stephen Smith, a professor of bioresource systems at Imperial College London, said their presence was an indicator of how deeply embedded plastic is in our lives.
He said synthetic fibres washing off during a machine cycle was one of the biggest contributors of microplastics into the wastewater system, since the government banned the use of microbeads in 2018.
“These things are in our homes, our environment is impregnated with them,” he said.
The report will be explored in depth in Tuesday night’s File on 4 on BBC Radio 4 at 8pm.
One report from Anglia Ruskin University last year indicated that microplastics in soil could cause worms to lose weight.
But Professor Smith cautioned that the impact of microplastics on soils was only likely to be seen decades in the future and said the report was a wake-up call to deal with harmful pollutants before they make it into wastewater.
“We need to be more responsible,” he said. “I think people would be horrified if they knew the extent of chemical use in their homes and where they work.”
The water companies, which have a legal responsibility to dispose of the waste, provide the sewage to farmers free or at minimal cost as treated biosolids.
Most is applied to land growing arable crops such as wheat or barley, but it can also be used on fruit and vegetable crops.
The practice is supported by the National Farmers Union and Defra as a nutrient rich alternative to fertilisers. It is not approved for organic farming but the Soil Association, which certifies organic foods, has called for its use to be expanded, if checks are tightened.
NFU environment forum chairman, Phil Jarvis said: “When used according to regulation and best practice requirements, certified biosolids provide the agricultural sector with a valuable and sustainable fertiliser.”
The practice is highly regulated but the list of contaminants that are checked for date back to the 1980s, when the biggest concerns were toxic metals as a byproduct of heavy industry.
The antibiotic Triclosan, which has been linked to antibiotic resistance, is among the many potentially harmful toxins identified in the report as present in wastewater which are not tested for under current regulations.
Water UK, the industry body for water companies, said: “Robust research from the UK and across Europe shows conclusively that sludge recycling allows nutrients to be returned to the land in a way that is safe, sustainable, good for farmers, and good for the environment.”
The Environment Agency is expected to begin the process of updating its regulations over the use of sludge in the coming months. It said: “We take our responsibility to protect the environment very seriously, which is why we commissioned this report.”
Asda and Sainsburys are among supermarkets that allow biosolids to be used on their products and said they expected suppliers to conform to all legal requirements and industry standards. Others, including Marks and Spencer and Co-Op, refuse produce from farms where human effluent is used.