Slime protects community from asbestos-lined water pipesAirborne asbestos is extremely dangerous, even in small but regular amounts. Waterborne asbestos fibers, on the other hand, are different. It's unclear at what threshold the presence of asbestos in drinking water begins to have a negative effect on public health. But one Canadian city may not have to find out, thanks to a slime growing in its asbestos cement water pipes.
According to microbiologist Ray Cullimore of Regina, Saskatchewan, bacteria growing in the capital city's water pipes appears to be preventing residents from ingesting as much asbestos as they otherwise would.
He explained that four different species of microbes line the water pipes beneath the city. These bacteria form a thin, harmless slime over the pipe walls, making a barrier between the asbestos and the water.
And that's not all - Cullimore said that these microorganisms actually draw the fibers from the cement, coat them with an organic goo (called a "patina") that renders them harmless and then set them free in the water.
What is asbestos doing down there?
The first question one might be inclined to ask about all this is, what is asbestos doing in water pipes in the first place? Cullimore had an answer for that. In an interview on the local radio station CJME News Talk 980, he explained that engineers added asbestos to a number of structures in the 1950s, even those that didn't need fireproofing.
"The asbestos was put in the cement with the very best of intentions, because the asbestos gave strength to the cement, and the general premise was that it's a fiber-reinforced concrete," he explained to his hosts. "It must work better than the standard concrete, and it did."
Of course, the presence of asbestos in any publicly used utility today is likely to scare people. But Cullimore said that the residents of Regina can relax for two reasons. First, waterborne asbestos is not as harmful as the aerosolized kind. And second, tiny microorganisms are keeping asbestos out of the water supply anyway.
Inhaled vs. ingested
Exposure to asbestos on the air is extremely dangerous, as it can cause asbestosis, malignant pleural mesothelioma and other severe respiratory conditions. But, perhaps counterintuitively, ingesting small amounts of asbestos through drinking water is not as toxic.
The U.S. Environmental Protection Agency estimates that up to 7 million asbestos fibers per liter of drinking water is safe for consumption.
Of course, many people would prefer to avoid asbestos exposure of any sort. For residents of Regina, bacteria are helping them do just that.
Cullimore added that, just as dry, friable asbestos should be left alone (or only be removed with care), so should this protective slime be preserved.
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