The American Society for Microbiology (ASM) would like to comment on the proposed National Pollutant Discharge Elimination System (NPDES) permit regulation and effluent limitations guidelines and standards for Concentrated Animal Feeding Operations (CAFO) rule published January 12, 2001, in the Federal Register.
The ASM is the premier educational and scientific society dedicated to the advancement of microbiological research and its application for the common good. The Society represents more than 42,000 microbiologists, including scientists in academic, industrial and government institutions, working in a variety of areas, including medical, genomic, molecular, environmental and food microbiology, and public health.
The ASM commends the Environmental Protection Agency (EPA) for addressing the ecological and human health effects on our nation's water systems from CAFOs. The ASM is especially pleased to see that the proposed rule acknowledges the importance of pathogens as manure constituents that contaminate ambient waters and aquifers and other environmental media, such as food crops, edible shellfish (especially bivalve mollusks). Discharges from CAFOs can result in excessive nutrients (nitrogen, phosphorus, and potassium), oxygen-depleting substances, and other pollutants accumulating to harmful levels in the water. This pollution threatens fish and shellfish, causes excessive and destructive alga growth, harms marine mammals, and contaminates drinking water.
Unfortunately, a majority of the measures proposed in the rule are inadequate to controll microorganisms, which pose a significant threat to human health through contamination of the environment, and water systems in particular. While the proposed rule does mention several measures that could effectively control pathogens in animal manure, they are not expected to be adopted or enforced in the proposed rule. Specifically, many of the proposed treatment and management technologies are inadequate to control pathogens and do not appreciably destroy these microorganisms.
The ASM offers the following recommendations in an effort to address public health deficiencies and environmental quality issues found in the proposed CAFO rule.
- ISSUE: The proposed rule notes that thermophilic processes such as composting, thermophilic digestion and other high temperature processes will greatly reduce pathogens. It also notes that alkaline processes (those that elevate pH to 12), such as lime stabilization, will also reduce pathogens. However, these processes are not required under the proposed rule and are only listed as options along with other methods that may not reduce pathogens.
SOLUTION: The proposed rule should require processes that will greatly reduce pathogens, such as, the thermophilic processes and alkaline stabilization in all manure treatments. The proposed rule should also stipulate that these processes be applied before land application or any other form of environmental release that could result in off-farm transport.
- ISSUE: The proposed rule does not set required pathogen reduction levels (percent or log10 reductions) or final pathogen concentration amounts in treated effluents or solids (biosolids) prior to land application or other disposal methods. Without such requirements, high concentrations of manure-associated pathogens will continue to be released into the environment under the proposed rule. It is important to note that after land application or other environmental release methods, the applied material and its pathogen load will not be easily contained or controlled because of exposure to natural environmental forces and phenomena, such as precipitation events.
SOLUTION: The EPA could address this by requiring target pathogen levels in treated wastewater effluents and residual solids (biosolids) similar to those set for municipal wastewater effluents and biosolids that are land-applied or otherwise released in the environment. If end-product pathogen criteria and standards are appropriate and required to protect public health from domestic or municipal wastes, then there is no reason why those same public health benefits should not be applied to animal wastes. Therefore, the proposed rule should include provisions for pathogen analysis, as it is required for municipal wastewater discharges and biosolids.
- ISSUE: Establishing setbacks or buffer zones.
SOLUTION: While the creation of setbacks or buffer zones will prevent the application of manure and wastewater within 100 feet of surface waters, tile drains, sinkholes and agricultural drainage wells, additional measures are necessary. The proposed rule should require setbacks or buffer zones be supplemented with extensive vegetative cover to reduce pathogen penetration of the setback or buffer zone. The lack of such vegetation requirements will increase the likelihood of surface and ground water contamination.
- ISSUE: The proposed rule suggests that manure be applied based on agronomic rates for nutrients, such as nitrogen and phosphorous.
SOLUTION: Such a management plan and application strategy will not assure that pathogens will be adequately controlled to prevent serious ground and surface water contamination. Research has shown that current nutrient-based manure application rates have caused serious pathogen contamination of both surface and ground water systems. Therefore, the continued use of these nutrient-based land application rates will continue to deliver high levels of pathogens to the environment, further contaminating surface and ground water. Alternative indicators such as testing for antibiotic resistance markers in bacteria associated with animal feeding operations could be developed and used to examine fate transport and off-lot water quality impacts.
- ISSUE: Once applied, control over the transport, survival and fate of pathogens in land applied material is subject to many environmental phenomena that can lead to pathogen persistence and dissemination. In particular, during storm (precipitation) events, pathogens in land applied manure can potentially run off into nearby waterways and infiltrate into ground water. The EPA must provide scientifically sound methods to contain pathogens during such events to prevent off-farm pathogen persistence and transport.
SOLUTION: Under the storm water and Total Maximum Daily Load (TMDL) rules, the EPA should consider using source tracking techniques (e.g., ribotyping, multiple antibiotic resistance) to monitor fecal bacteria in run-off associated with a specified amount of rain at CAFOs of certain sizes. Retention ponds and other types of storm water control methods should also be monitored.
The EPA estimates that under the proposed rule, there will be a 50% reduction of fecal coliforms and a 60% reduction of fecal streptococci in surface waters. This level of reduction is entirely inadequate because high concentrations of pathogens will still be present in many impaired surface and ground waters. In many of these impaired surface and ground waters the levels of pathogens will still be unacceptable for primary contact recreation, for harvesting of bivalve molluskan shellfish, for irrigation of crops eaten raw and as sources of drinking water for both public and private supplies. While public water supplies may be able to reduce pathogen concentrations in impaired waters by treatment processes, many rural dwellers rely on untreated private water supplies and will remain at risk. Serious human health risks will not be addressed, such as E. coli 0157 H7, cryptosporidium, antibiotic resistant bacteria, unless the proposed rule is modified to monitor and control the pathogens of concern. Therefore, the ASM encourages the EPA to include microbial-based monitoring and standard setting, along with science-based risk reductions to ensure a healthy environment and provide adequate public health safety.
The ASM is pleased to have the opportunity to provide comments in response to the proposed rule on the NPDES permit regulation and effluent limitation guidelines and standards for Concentrated Animal Feeding Operations and hopes that these comments and recommendations are of assistance to the EPA.