Journal of Toxiocology and Environmental Health (JTEH)

Managing Health Risks from Drinking Water: A Report to the Walkerton Enquiry

The drinking water supply system of the Ontario community of Walkerton became contaminated with deadly bacteria in May 2000 resulted in 7 mortalities and illnesses in 2,300 people among the 4,800 residents. Owing to the magnitude of the outbreak an enquiry commission was established to determine not only the factors involved in the Walkerton situation, but also potential human health impacts of municipal drinking water systems in general. This enquiry commission conducted a series of investigations to provide background information that would assist the commission in formulating recommendations to strengthen the Ontario drinking water system regulations. One of the reports was prepared by a team of experts at McLaughlin Centre for Population Health Risk Assessment that provided information on strategies to assess and manage health risks associated with contamination of drinking water with an emphasis on microbial contamination. This report was published in a special issue of the Journal of Toxicology and Environmental Health, Part A (Volume 65, Number 21:1633-1823) in 2002 with Guest Editors Vic Armstrong and Paula Carty.

In this special issue a comprehensive drinking water health risk assessment and management practices were described with a reference to the Walkerton study. A guide to the structure of the report was provided at the beginning followed by comprehensive evaluation in 5 major topics:

  1. management of population health risks,
  2. history of water-related disease outbreaks in Canada and the United States,
  3. measurements of microbiological water quality,
  4. development of drinking water standards, and
  5. strengthening drinking water management practices.  

In the first part of this published volume a detailed description of 6 risk management frameworks developed in North America was provided. The method of implementing such frameworks in developing national standards was also described. In addition, the public perception of risk and the factors influencing their perception were also examined. In the second section of the published volume, a list of water-borne pathogens was provided along with a brief account on some historical outbreaks in Canada and the U.S. In the next portion of the paper, the methodology for detection and measurement of microbial contaminants, along with strategies to monitor them was described. In the fourth section, the technical and administrative approaches in setting the standards or guidelines for drinking water quality in Canada, Ontario, the U.S, Australia, and the World Health Organization were described. In the final part of the paper some suggestions were made to improve or strengthen the drinking water management practices by (1) using recent developments to enhance surveillance practices,  (2) utilizing new technology to better characterize microbiological risks, (3)  improve source water protection, and (4) adopt a total quality management approach to attain safe drinking water practices. The authors acknowledged that a zero risk is not attainable; however, it was expected that risk could be minimized with these new enhancements.

Krewski D, Balbus J, Butler-Jones D, Haas C, Isaac-Renton J, Roberts KJ, Sinclair M. Managing health risks from drinking water--a report to the Walkerton inquiry. J Toxicol Environ Health A. 2002;65(21):1633-1823.

Published twenty-four times per year, the Journal of Toxicology and Environmental Health, Part A features strictly refereed original research in the field of environmental toxicology in general as well as in special interest fields such as target organ toxicities, immunotoxicology, risk assessment, carcinogenesis, mutagenesis, ecotoxicology, environmental factors affecting health, and aquatic toxicology.
Subscription information for the Journal of Toxicology and Environmental Health, Part A or a sample copy can be obtained from the address below.  To view the special issue (Vol. 65, Number 21), go to

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a sample copy, contact:
Taylor & Francis
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To submit an article, contact:
Dr. Sam Kacew
McLaughlin Centre for Population Health Risk Assessment
Institute of Population Health, Room 310
University of Ottawa
Ottawa, Ontario
K1N 6N5