Sunday 25 February 2007

Is Our Drinking Water Carcinogenic? What Can we do?

The governing bodies of Europe and United States seem to be convinced that nitrite in drinking water is not associated with any adverse effect other than methemoglobinemia, a very rare disease of infants. The no-observed-adverse-effect-level (NOAEL) is, therefore, 500 m g/L N in NO2 in Europe and 1000 mg/L in U.S. Studies in China indicates a very strong link. The PMCL of nitrite for groundwater recharge is thus  20 mg/l and for purified drinking water is only 2 mg./L. 

The nitrite concentration in drinking water if U.S. and Europe is several hundred micrograms per litter, and the cancer mortality rate is high, up to 250 or more persons per 100,000 population. The nitrite concentration in rural communities of Asia and Africa is commonly only a few micrograms per liter, and the cancer death rate is only several persons per 100,000 population is very low in African and in Asia. Where China is rapidly urbanized, as in the Pearl River Delta area, the nitrite level in drinking water and the cancer mortality rate approaches that of the developed countries.

 One explanation of the stastistics is to blame on the praxis of sewage-treatment plants where biodegradation under oxidizing conditions produces vast amount of nitrite to contaminate the sources of our drinking water. The issue is still convertroversial, but one need not take a risk, while waiting for a definitive answer. Many have started to buy "purified drinking water" from supermarkets. A more fundamental solution is a reform of the sewage-treatment praxis to insure the supply of  nitrite-free water.

I made an invention to de-nitritize polluted or waste water. Instead of biodegradation, I used a super-filter, called hydrotransistors, to filter out particulate matter down to micron-size. The dissolved phosphates, nitrates, and nitrites are then removed by natural processes of culturing diatoms, fish, and other aquatic organisms. Experiments show that we can achieve total de-niitrification of filtered -water.
If you would like a copy of the Abstract please contact me at kenhsu@aol.com

(Abstract of a lecture to be delivered at Beijing University in March, 2007)

 

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