NEWSGOVERNMENT Final drinking water monitoring rule set for June A final rule to mandate nationwide monitoring of drinking water for microbes and disinfection byproducts is slated to be promulgated this June [Federal Register, 59, 58245), according to Stig Regli, regulation manager for the rule. Under the rule, all public water systems that use surface waters or groundwater influenced by surface waters and serve 10,000 to 100,000 people will test their source water for Cryptosporidium, Giardia, fecal coliforms, and total coliforms. Systems serving > 100,000 people and drawing water from the same types of source waters would monitor for the above pathogens plus total culturable viruses. The large systems will also run tests on finished water if pathogens are detected in the source waters. All systems will have to provide EPA with engineering details related to removal of microorganisms. In addition, all systems serving > 100,000 people will analyze for certain disinfection byproducts. Monitoring is expected to last as long as 18 months. According to EPA, 1725 treatment plants will be involved in the microbial monitoring, and almost 300 plants in disinfection byproduct analysis. The water monitoring was proposed last February (Federal Register, 59, 6332) and was expected to begin in late 1994. However, the start has been delayed by the development of protocols for detecting microbes in different environmental matrices, says Regli. EPA is relying on immunofluorescence to detect Cryptosporidium and other protozoans, but the procedure "is complex and open to error," says EPA senior microbiologist Paul Berger. Following preparation of a sample, protozoan cysts and oocysts (cysts and oocysts are the protective walled stage in the protozoan life cycle during which the parasite waits for a host) are identified under a microscope by specific criteria for immunofluorescence, size, shape and internal morphology.
Initial testing of commercial laboratories in 1991 and 1992 revealed that the recovery efficiency—how well each laboratory could quantitatively identify the pathogens in a sample—varied significantly. EPA responded, says Berger, by tightening the procedures and even listing brand names for materials to standardize lab practices. What followed has been the development of quality assurance and performance evaluation sample protocols to aid laboratories in performing immunofluorescence in the presence of various environmental interferences. As of November, says senior microbiologist Stephen Schaub, the method still at times failed to detect protozoans in water samples with high turbidity or algae. Nevertheless, says Schaub, "the methodologies are fairly firm." He expects that a round robin of about 10 labs to evaluate the method's recovery accuracy and precision will begin this month. Schaub estimates that
when the rule is finalized as many as 50 commercial laboratories may offer the method. Immunofluorescence has been criticized because it fails to differentiate between live and dead (viable and nonviable) waterborne Cryptosporidium oocysts, or between infectious and noninfectious strains of the parasite. "However, we don't need great accuracy," says Berger. The data on pathogen densities in raw water will be used in the related surface water treatment rule (see pg. 17A) to determine what utilities must do to reduce microbial levels in their finished drinking water. Those proposed actions are triggered by density values that vary by a factor of 10. EPA is also examining new methods for the future, says Berger. Electrorotation, now under development in Great Britain, promises better cell counts and may distinguish viable cysts. However, the method has yet to pass muster in a peer-reviewed journal. —ALAN NEWMAN
INVESTIGATION NRC to look at incinerators, human health Public confusion and distrust of incineration have led to a new study by the National Research Council (NRC) of waste incineration and its impact on human health. This month the newly created NRC Committee on Health Effects of Waste Incineration will start meeting to explore the relationship between waste combustion and human health, says Raymond A. Wassel, NRC committee staff officer. Wassel notes that the study is sponsored by a mix of federal agencies that are responsible for incinerator regulations as well as some that deal with environmental and health issues: EPA, the Agency for Toxic Substances and Disease Registry, and the Department of Energy. The newly created 18-member committee will be chaired by Donald Mattison, dean of the School of Public Health at the University of Pittsburgh, and will issue its final report in September 1996. The study will look into a broad spectrum of issues: incinerator siting, design, and operating conditions, and public perceptions about waste combustion. All types of combustors—hazardous, medical, municipal waste and cement kilns, industrial furnaces and boilers—will be examined, as will their impact on human health. The study will be done while EPA is immersed in drawing up and implementing new standards for incinerators. Wassel says the committee will be watching regulations proposed or finalized by EPA but will not provide "real-time advice." Rather, it will address long-term issues, including alternatives to burning wastes. —JEFF JOHNSON
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