U V Light

NEWS

Ultraviolet light makes fingernail polish dry faster. It binds polymers so that ink from glossy magazines doesn't rub off on readers' hands. And for many years, particularly in Europe, it has been used as a primary treatment for water systems to kill bacteria and viruses.

Now, the federal Environmental Protection Agency has said that it is considering a new use that, especially in places like New York City, could have perhaps the biggest financial and environmental effect of all: killing a different form of waterborne microorganism, protozoans.

Protozoan parasites, like giardia and cryptosporidium, which have become a major health concern around the country in the past decade, had been considered immune to ordinary water-cleaning systems until the past few years. Chemical systems like chlorination do not do the job, and so, the federal agency had said, cities would simply have to get better at removing the organisms with filtration plants.

New research, however, has found that ultraviolet light is effective in killing those protozoans, which can cause life-threatening intestinal illness in humans, especially people with weakened immune systems.

Link: http://www.nytimes.com/2001/07/29/science/29WATE.html

Comment: You can buy a UV water filter at an aquarium shop.