In today`s society, readers of newspapers should expect rational and balanced perspectives on complex environmental issues that confront Canadians. It was with considerable dismay, therefore, that we read the recent article entitled, "Scientist's Open Letter on the Dangers of Biosolids" by Dr. Sierra Rayne, John Werring, Dr. Richard Honour, and Dr. Steven R. Vincent (Rayne et al.) on the issue of biosolids management. We feel that the authors of the article have misrepresented many aspects about the management of biosolids and in particular have unfairly demonized the practice of applying biosolids onto agricultural lands. As scientists with significant experience researching the environmental impact of biosolids, we wish to respond with a more balanced perspective on the issue of managing biosolids in Canadian society; a perspective based on evidence......
Biosolids are not the "toxic stew" that Rayne et al. attempt to portray. The "sludge" that collects in wastewater treatment plants is treated through sophisticated, engineered processes such as anaerobic digestion, composting, or alkaline stabilization before it becomes the biosolids end-product. Sludge treatment reduces odour and levels of pathogens, as well as enhancing degradation of many organic chemicals. When biosolids are applied carefully and judiciously to agricultural soils, this material adds nutrients to the soils that benefit crop production and reduce the need for chemical fertilizers. In most jurisdictions across Canada, applying biosolids to agricultural fields is strictly regulated. In Ontario, the maximum application rate is 22 tonnes/hectare every 5 years, with regulated waiting periods for both harvest and animal grazing to provide additional time for pathogen die-off and degradation of organic chemicals. The Canadian Council of Ministers of the Environment endorses land application as a sustainable and responsible method of managing biosolids, as do most provinces and territories that regulate biosolids. By focusing exclusively on the occurrence of chemicals in biosolids, Rayne et al. have stoked fears among the public about exposure to toxic chemicals....
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