The Environmental Protection Agency’s regulations on land application of sewage sludge are not strict enough to protect human health or the environment, according to a report released recently by the Waste Management Institute at Cornell University.
The report said that EPA 503 rules, which were adopted in 1993, do not adequately protect against contaminants in sludges, including heavy metals, toxic organic materials such as polychlorinated biphenyls, and pathogens such as bacteria and viruses. The report recommended that EPA conduct a risk assessment that uses more conservative assumptions in establishing permissible levels of contaminants.
It also calls for the establishment of standards for additional contaminants, further assessment of risks to groundwater and surface water, and the application of clean sludges or smaller quantities of sludges to prevent the accumulation of pollutants in the soil.
Since the authors live and work in New York State, they expressed particular concern about the soil, water and crop characteristics that might be impacted by biosolid contaminants there. Some soils in the region have low pH which tends to increase metal availability, and a number of crops are sensitive to phytotoxic metals. The soils tend to be shallow, increasing concerns for groundwater contamination. Dairy farming is also a major agricultural use, so that application of additional nutrients from sludges to those already provided by manure application may result in excessive nitrogen and phosphorous.
The report, “The Case for Caution,” may be downloaded from the Internet at http://www.cfe.cornell.edu/wmi, or obtained by calling 607-255-1187.
