Taste and Odour and Health, Ontario Water Works Research Consortium

T&O and Health

Taste and odour is an aesthetic objective and not a health related objective for drinking water. At the present time, no health related guidelines or regulations are known to exist for geosmin or MIB anywhere in the world. The World Health Organization Drinking Water Quality Guidelines (WHO, 2004) indicate that the taste and odour of drinking water should not be offensive to the consumer, however, no health-based guideline value is proposed. The United States Environmental Protection Agency (USEPA, 1992) has set an unenforceable secondary standard (aesthetic effect) indicating that a threshold odour number should not be exceeded (for taste and odour in general). The Australian Drinking Water Guidelines simply state that the taste and odour of drinking water should be acceptable to most people (ADWG, 2004). Similarly, the Guidelines for Canadian Drinking Water Quality indicate that both taste and odour should be 'inoffensive' (Health Canada, 2006). Taste and odour compounds can be detected at very low concentrations, with the average person noticing the odour of geosmin at as little as 4 nanograms per litre (ng/L). (A trillion nanograms equal one gram) MIB is usually noticeable at levels of approximately 9 ng/L.

The Ames test has been widely used since the 1970s as a preliminary screening tool for potential carcinogens. Neither geosmin nor MIB is mutagenic as determined by the Ames test (Dionigi et al. 1993; Nakajima et al. 1996). The fact that neither geosmin nor MIB are mutagenic makes them unlikely candidates as potential carcinogens and has limited further research into their potential health effects. No research involving potential health effects of these two compounds has been conducted in humans.

References

Dionigi, C.P., Lawlor, T.E., McFarland, J.E. and Johnsen, P.B., 1993. Evaluation of geosmin and 2-methylisoborneol on the histidine dependence of TA98 and TA100 Salmonella typhimurium tester strains. Wat. Res., 27(11), 1615-1618.

Nakajima, M., Ogura, T., Kusama, Y., Iwabuchi, N., Imawaka, T., Araki, A., Sasaki, T., Hirose, E. and Sunairi, M., 1996. Inhibitory effects of odor substances, geosmin and 2-methylisoborneol, on early development of sea urchins. Wat. Res., 30(10), 2508-2511.

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