| Balancing the Risks and Benefits of Drinking Water Disinfection: Disability Adjusted Life-Years on the Scale Arie H. Havelaar, Augustinus E.M. De Hollander, Peter F.M. Teunis, Eric G. Evers, Henk J. Van Kranen, Johanna F.M. Versteegh, Joke E.M. Van Koten, and Wout Slob National Institute of Public Health and the Environment (RIVM), Bilthoven, The Netherlands Abstract
To evaluate the applicability of disability adjusted life-years (DALYs) as a measure to compare positive and negative health effects of drinking water disinfection, we conducted a case study involving a hypothetical drinking water supply from surface water. This drinking water supply is typical in The Netherlands. We compared the reduction of the risk of infection with Cryptosporidium parvum by ozonation of water to the concomitant increase in risk of renal cell cancer arising from the production of bromate. We applied clinical, epidemiologic, and toxicologic data on morbidity and mortality to calculate the net health benefit in DALYs. We estimated the median risk of infection with C. parvum as 10-3/person-year. Ozonation reduces the median risk in the baseline approximately 7-fold, but bromate is produced in a concentration above current guideline levels. However, the health benefits of preventing gastroenteritis in the general population and premature death in patients with acquired immunodeficiency syndrome outweigh health losses by premature death from renal cell cancer by a factor of > 10. The net benefit is approximately 1 DALY/million person-years. The application of DALYs in principle allows us to more explicitly compare the public health risks and benefits of different management options. In practice, the application of DALYs may be hampered by the substantial degree of uncertainty, as is typical for risk assessment. Key words: bromate, Cryptosporidium parvum, disinfection, drinking water, ozone, quality of life, risk assessment. Environ Health Perspect 108:315-321 (2000) . [Online 21 February 2000] http://ehpnet1.niehs.nih.gov/docs/2000/108p315-321havelaar/ abstract.html Address correspondence to A.H. Havelaar, Microbiological Laboratory for Health Protection, National Institute of Public Health and the Environment (RIVM) , PO Box 1, 3720 BA Bilthoven, The Netherlands. Telephone: 31 30 2742826. Fax: 31 30 2744434. E-mail Arie.Havelaar@rivm.nl We thank D. Habbema and M-L. Essink Bot. We also thank P. Kramers and J. Melse for discussions on methodology and presentation of quality-of-life-related measures in public health decision making ; K. Blair for the data on the mortality risk associated with cryptosporidiosis ; and C. Haas, D. Wolf, and the reviewers for helpful comments on draft manuscripts. Received 29 July 1999 ; accepted 26 October 1999.
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