Scientists seek to assess the microbial risks in the water we drink

The report focuses on microbial risk assessment, a relatively new tool for addressing the problems of waterborne infectious diseases that provides a formal process for quantifying the health risks from pathogenic microorganisms.

“Microbial risk assessment is an evolving field, and it requires an interdisciplinary, collaborative approach,” LeChevallier explains. “Much more research is needed to fill gaps in our understanding of waterborne pathogens and to determine the current rate of waterborne illness.”

The report is the result of a colloquium convened by the American Academy of Microbiology in October, 2006. Experts in diverse fields with expertise in water quality and analysis – including microbiology, public health, engineering, epidemiology, medicine, and water science – discussed some of the controversial topics in microbial risk assessment, research that could move the field forward, and the need for increased training and better communication with the public. The report is a record of their discussions and recommendations.

During an outbreak situation, scientists and public health officials have many questions to address. Which water treatment option is best" Who are the most sensitive members of the population, and how can they be protected" Where should efforts and resources be directed" What are the most dangerous pathogens found in the water, and how did they get there"

Microbial risk assessment addresses all these questions by offering a formalized approach for identifying the risks that arise from contact with pathogenic microorganisms, including certain bacteria, viruses, and microscopic eukaryotes. Microbial risk assessment also can help guide management decisions, identify sensitive groups, spot critical pathogen control points, and aid in the assessment of the adequacy of drinking water treatment barriers.

The report describes the scientific methods involved in microbial risk assessment, addresses the current challenges facing this evolving field, and offers a number of recommendations, including:

• An international database of pathogen occurrence in drinking water and ambient waters should be established. This would inform microbial risk assessment, risk management, and enable the implementation of effective public health initiatives.

• An independent microbial risk assessment advisory board with members from both industry and academia, and with international representation, should be assembled. This advisory board could foster the most consistent use of the best techniques for evaluating the problems of public health and ambient water.

• The general public needs to know basic information about their source and treatment of drinking water, the need for future treatment upgrades and infrastructure enhancements, and the fundamentals of microbial risk.

• Additional research is needed to validate numerical guidelines, such as the EPA’s microbial water guidance of one illness per 10,000 individuals in a given year. Numerical guidelines are useful, but may not be suitable for all water exposures.

• Microbial risk assessment needs to broaden the use of available epidemiologic data. Studies are needed to integrate outbreak data to better estimate microbial infectivity under real-world conditions.

A full copy of the report and further recommendations can be found on the Academy website at www.asm.org/colloquia. Ninety-second pod casts, originally aired as part of the American Society for Microbiology’s radio series, are available for download at this website. To receive a printed copy of Clean Water: What is Acceptable Microbial Risk", email the Academy at colloquia@asmusa.org.

The American Academy of Microbiology is the honorific leadership group of the American Society of Microbiology. The mission of the Academy is to recognize scientific excellence, as well as foster knowledge and understanding in the microbiological sciences. For more information about the American Society for Microbiology, contact Barbara Hyde at 202-942-9206 or visit www.asm.org