Triclosan is often used in personal and household cleaning products to improve their efficacy in controlling and eliminating bacteria. This has resulted in the chemical compound finding its way into municipal wastewater. If the removal of triclosan from wastewater treatment plants (WWTPs) is incomplete it may spread into biosolids that are being used as fertilizers.

The substance phenol, 5-chloro-2-(2,4-dichlorophenoxy), also known as triclosan, is an industrial chemical. It does not occur naturally in the environment. It is used as a material preservative in the manufacture of textiles, leather, paper, plastic and rubber to stop the growth of bacteria, fungus, mildew, and to prevent odours.

University of Guelph has conducted a study to investigate if the presence of triclosan in biosolids poses any harm to public health. The study proponents have concluded that the compound does not pose a threat to the food chain or environment.

The research funded by the Ontario Soil and Crop Improvement Association (OSCIA) addresses concerns about triclosan as a harmful component in biosolids. The research was overseen by Dr. Paul Sibley of the School of Environmental Sciences, with graduate student René Sahba Shahmohamadloo conducting the research as part of his Master’s thesis.

Gord Green, President of the OSCIA expressed relief upon hearing about the results. According to him, “Farmers apply the biosolids to their crop land as a soil amendment to capture organic matter and nutrients, so we are pleased to hear that the most commonly used antimicrobial does not affect the food or feed we grow, nor does it impact the surrounding environment. Biosolids are highly regulated so the recent research provides confidence for both the urban population and the farm community that it is a valuable resource – a win-win for both parties.”

“This research was unique compared to similar research across North America in that it included four formulations of biosolids across treatments of corn, soybean and spring wheat. Plant emergence and growth were studied at various stages to determine if there was any uptake of triclosan. Arbuscular mycorrhizzal fungi was also evaluated as part of an environmental assessment,” says Sibley.

Triclosan is not water-soluble with 98 per cent of the product removed along with biosolids at sewage treatment plants. According to Environment Canada, experimental evidence indicates that triclosan is not persistent in aerobic soil (with a half-life ranging from 3 to 58 days) under laboratory conditions. However, when applied as part of biosolids, field dissipation half-lives are 50 to 258 days. It does not bioaccumulate in soil organisms to a great extent based on studies conducted on earthworms and soybean plants. Based on the toxicity levels, effects in wildlife are not likely to occur. Overall, there is a low concern for negative effects in terrestrial organisms.

Ontario’s stringent regulations allow biosolids to be applied only once every five years on agricultural farm lands. It is not permitted on land used for fruit or vegetable production.

If you are a municipality in Ontario and in need of a biosolids management solution, please feel free to contact us at 1 (877) 479-1388.

Sources:
http://www.ec.gc.ca
https://www.ncbi.nlm.nih.gov

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