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EPA attacks report questioning safety of Taiwan's water

The quality of water in reservoirs and water treatment plants remains safe, with a very low level of microcystins -- toxins frequently associated with liver disease -- found in samples, the Environmental Protection Administration (EPA) said yesterday.

The EPA was responding to a report in the Chinese-language Minsheng Daily that claimed the level of microcystins in nine reservoirs exceed the acceptable level set by the WHO, posing a threat to tap water users.

Commonly found in lakes, ponds and reservoirs, microcystis bacteria produce natural toxins, called microcystins, that are very potent. Microcystins are hepatotoxic, and widespread scientific studies show that accumulation of the chemicals can cause liver damage.

Safe levels

EPA officials, however, rebutted the report by showing the results of a study on 10 reservoirs and nine water-treatment plants nationwide.

The study showed that among 314 samples of water collected from reservoirs and water treatment plants, the highest total concentration of microcystins (in nanograms per liter) was 278, which was far below the WHO's drinking-water standard of 1,000. This level was found in Taihu (太湖) Reservoir in Kinmen County.

According to the study, total microcystin concentrations in samples of treated water were all lower than 65.

"We don't see any danger in the current situation," Chen Chih-ming (陳志銘), a section chief at the Bureau of Sanitation and Toxic Substances Control, told the Taipei Times.

However, Chen said microcystin concentration in public water supply reservoirs varies and these changes deserve more attention.

"During droughts or on hot days, the microcystin concentration can climb dramatically," Chen said.

Real-time monitors

To ensure the safety of drinking water, Chen said this year the EPA will advise water-treatment plants to set up real-time monitoring systems to check toxin levels.

"Once the concentration starts climbing, plant operators should be wise enough not to draw water from the upper water column of the reservoirs. Microcystins mostly float on the surface or upper part of the water," Chen said.

Plants can further degrade microcystins through various chemical oxidants in the treatment process, Chen said.

Chen said risk assessment for microcystins in drinking water has been a hot topic for research in recent years because the chemical is included in the WHO's guidelines for drinking-water quality.

However, only a few countries, such as Australia and Canada, include the level of microcystins in their national drinking- water regulations.
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