Biosolids on Farmland

Policy on Applying Biosolids on Farmland
March 14, 2008
Passed by EFAO Board of Directors

  • Whereas sewage sludge (biosolids) is a unpredictable mixture of various chemicals,
  • Whereas there is little independent research being done to explore the effects of handling, applying and spreading of biosolids on farm land over a long term,
  • Whereas there is a high potential that the toxic components of biosolids being taken up by plants and water that is being used to feed livestock and their use for human consumption,
  • Whereas the risks of spreading biosolids and contamination of water and land is high and possible;

Therefore it should be resolved that EFAO supports a moratorium to ban the spreading of biosolids on farm land and to support and ask for independent research on long term effects on farmland and surrounding ecosystems.

Further Discussion around Concerns about Applying Biosolids on Farmland:

Biosolids are the dense concentrate left over after sewage treatment plants extract water from toilet and industrial waste coming from sewers. In Ontario, two-thirds of all sewage sludge is disposed of by spreading it on farm fields – 300,000 tonnes a year. Toronto alone contributes 80,000 tonnes a year.

Biosolids are praised for the high nutrient levels which are beneficial to the soil. But there can also be uncontrolled concentrations and mixtures of, namely: Bacteria, Viruses, Parasites, Endotoxins, Heavy metals like Arsenic, Lead, Mercury, Chromium, Cadmium, Molybdenum, Copper, Selenium, Zinc, Chemicals like PCB’s, PBDE’s (fire retardants), dioxins and furans, endocrine disruptors, polyaromatic hydrocarbons, and others discharged into sewers from home and industry as well as Antibiotics and other drugs flushed down toilets and drains.

There is little independent research on biosolids. Perhaps the most alarming development has been the research conducted by Cornell University examining historical biosolids spread fields in the US and Ontario. This study has discovered that significant amounts of the heavy metals in the biosolids have vanished from the plough depth of the fields. (The heavy metals are markers for some 10,000 potentially harmful chemicals in the sludge, which are not individually tested for.) Testing has revealed the metals did not migrate deeper into the soil, and while some leachate into surface waters was found, the rate of leachate could not account for the bulk of the missing material. The only clues to its disappearance were elevated levels of metals found in weeds adjacent to the spread fields.

One of the independent studies, a study by OME/OMAFRA/WTI in Ontario reinforces the findings. That study found dioxins in known historic biosolids spread fields had also vanished. While neither Cornell nor OME/OMAFRA is prepared to state the obvious, the logical assumption is that these harmful chemicals were absorbed into the plants grown as food and fodder crops and are contaminating the entire food chain from vegetables and fruit fertilized with sludge (tobacco is the only crop that cannot be grown in biosolids in Ontario) to the meat, eggs, milk, and prepared foods from animals fed sludge-contaminated feeds.

Another concern is e-coli contamination. Recent research showing that lettuce and spinach (the only plants tested) draw e-coli in through their roots so it cannot be removed by washing is also cause for concern. Biosolids contain 1.5 million e-coli colonies as part of the 5.8 billion coliform colonies per 1/2 cup, and the routine application is 8 tonnes per acre. Aside from the obvious danger of food and animal feed crops being infected there is the secondary risk of pathogenic leachate entering surface waters and being sprayed on berries and market gardens when watering in dry weather, or perhaps being inhaled by golfers breathing the aerosols off water sprayed on golf courses from the same sources.

E-coli is not the only hazard. It is a marker for every viral and bacterial disease organism from the sick people and disease carriers in the population, whose waste is concentrated in the biosolids and capable of infecting others. The US National Institute for Occupational Health (NIOSH) has issued guidelines for protecting workers with Class B sludge that are similar to protective measures for handling germ warfare agents, yet no warning signs are posted to protect the public from coming in contact with it on farm fields, and trucks carrying it do not require “hazardous waste” markings.

Because our health and the protection of the environment are at stake in the spreading of pathogens and toxins in form of biosolids on farmlands, it is imperative that the proponents of this practice prove “beyond a reasonable doubt” that what they are doing is safe. Such proof has not been forthcoming, and cannot be provided until the problems that are raised here are scientifically examined.

The Canadian Infectious Decease Society and the National Farmers Union have both called for an immediate moratorium on the spreading of biosolids. The Canadian Infectious Disease Society says regarding pathogenic biosolids, “a moratorium on their use is certainly in order where insufficient data exists regarding safety to the Canadian population. With so many question marks, opposing the use of biosolids on farmlands makes sense.”