Continuous Improvement

In a never-ending battle, another industry standard is being brought under fire on its scientific basis. A new report from the National Academies' National Research Council states the U.S. Environmental Protection Agency's (EPA) standards that govern using treated sewage sludge (biosolids) on soil are based on outdated science.

This time though, it was the EPA who asked the National Academies to convene a committee to conduct an independent evaluation of the technical methods and approaches used to establish the chemical and pathogen standards for biosolids. They specifically were to focus on health protection.

"There is a serious lack of health-related information about populations exposed to treated sewage sludge," said Committee Chair Thomas A. Burke, professor, Department of Health Policy and Management, Johns Hopkins University Bloomberg School of Public Health.

Under a 1993 Clean Water Act rule (Part 503), biosolids can be applied to land if it is treated to limit concentrations of certain chemicals and reduce disease-causing pathogens. These biosolids are applied to agricultural or other lands to improve the properties of the soil. Approximately 60 percent of the 5.6 million dry tons of sewage sludge disposed of annually in the United States are land applied.

According to the committee, methods for assessing the health risks caused by exposure to chemicals have evolved substantially since the 1993 rule was established. In addition, EPA used an unreliable 1988 survey to identify chemicals to regulate and since then new chemicals have been identified as concerns. A new survey and revised risk assessments were proposed.

However, the committee agreed with EPA's general approach for regulating pathogens. EPA established requirements to reduce pathogens by treatment or a combination of treatment and use restrictions. The report found no documented scientific evidence of the EPA's standards failing to protect public health.

The report did suggest that the agency use new pathogen-detection technology to ensure that treatments are available. It also suggested that EPA increase its efforts to ensure that companies producing biosolids meet the regulatory requirements to remove or neutralize chemicals and pathogens.

The fact is just 30-years ago, thousands of American cities dumped their raw sewage directly into our nation's rivers, lakes and bays. Now, only biosolids that meet the most stringent standards spelled out in the Federal and state rules can be approved for fertilizer.

I remember when I was a kid, my family loaded up the car trunk with untreated cow manure from a relative's farm in downstate Illinois and drove back to Chicago so we could put it in the garden. Obviously, waste treatment has come a long way since then. As with many EPA rules, a little reassessment to make sure that standards are still based on current data might be a good idea.