02
Mar
Sewage Sludge Creates a “Safe Haven” for Covid Viral Particles, Placing Public Health at Risk
(Beyond Pesticides, March 2, 2022) Covid (SARS-CoV-2) is being detected in wastewater, sludge, and biosolids, providing a “safe haven” for the virus and creating a health risk for wastewater workers and farmers. Published in Geoscience Frontiers, an international team of researchers systematically reviewed the available literature on the prevalence of pandemic coronavirus in wastewater in order to better determine risks to workers and public health. The timely review comes as many communities and states are reevaluating their use reclaimed human effluent due to a range of toxic contaminants, including per and polyfluoroalkyl substances (PFAS).
Researchers found 20 articles from published literature that met the criteria for their review. Each of three environmental materials –wastewater effluent, sludge, and biosolids were analyzed for the presence of Covid. Effluent is the liquid that remains after a sewage treatment process, sludge is organic matter separated from effluent, and biosolids are the fully processed product that is then often applied to farm fields.
Of the three materials, sludge contained the highest prevalence of covid RNA, followed by biosolids and then effluent, according to modeling of the data employed by researchers. Covid amounts were found to be related to the number of infected individuals living within the bounds of a treatment plant, as well as the treatment approach utilized by the plant.
Covid is an enveloped virus, and as such contains a hydrophobic envelope layer. As a result, the virus is apt to latch on to solid particles present in the wastewater stream. Researchers found that greater amount of solids and longer retention times (amount of time the effluent is stored) increase the rate of Covid RNA detection. Further, suspended solids in wastewater retention tanks have the potential to block UV light that may otherwise breakup the virus.
Scientists indicate that if proper guidelines are not in place, the routes of transmission through environmental materials are “numerous.” Accordingly, wastewater workers, who can be exposed to these materials for long periods of time, are at high risk. “The inevitable inhalation of the virus-laden aerosols generated during the wastewater and sludge processing activities, especially without adequate protection, could also lead to fecal-oral transmission of the virus,” the authors write.
The data indicates that conventional wastewater treatment is not effective at entirely removing Covid RNA from the waste stream as it processes these materials for reuse. Although citing studies on potential transmission, authors do note that there is not clear agreement in the literature that the genetic materials found in these waste streams are directly contributing to the spread of viral infection.
The authors suggest the use of “adequate protections, including the use of personal protective equipment should be ensured for the wastewater/sludge workers, while the use of reclaimed wastewater and other materials like sludge and biosolids should be done with caution, especially in rural settings of developing and low-income countries where water, sanitation, and hygiene are insufficiently deployed.” The article also suggests methods to better ensure the elimination of Covid RNA, including best practice treatment measures.
However, even if concerns over Covid RNA are addressed, wastewater products still pose a range of pubic health concerns. Biosolid/sludge products have been found in the past to contain residues of hazardous pesticides, heavy metals, antibiotics and other pharmaceuticals, personal care products, and a range of other toxicants. A 2018 report from the U.S. Environmental Protection Agency’s Office of Inspector General identified over 350 pollutants in biosolids, 61 of which are considered hazardous. A recent study conducted by the Sierra Club and the Ecology Center found PFAS in every biosolid fertilizer sold to consumers at hardware stores. With even the most highly processed consumer-forward biosolids contaminated with hazardous materials, many communities and states are rethinking their use of these products.
In Oklahoma, the small town of Luther in 2020 voted to ban the use of biosolids on farmland. This has led Oklahoma state senator Shane Jett to introduce a state-level prohibition on the use of human raw sewage on agricultural land. Concern over PFAS in Maine led to legislation that would likewise ban the use of sludge or sludge-derived products unless a laboratory test confirms PFAS below a certain level to be determined by state agencies.
As the worst of the coronavirus pandemic appears to be in the rear-view mirror, it is critical that steps are taken to address all potential routes of exposure. As Beyond Pesticides continues to track this story, read more about the hazards associated with the use of environmental materials in agriculture through the reports Wastewater Irrigation on Farms Contaminates Food, and Biosolids or Biohazards.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: Geoscience Frontiers, News-Medical
