"Because the chlorides are so cheap, they will stay (in the marketplace) for a long time," Shi said. "The big picture is pretty scary."
Shi said that there are increasing reports of salt in drinking water supplies that occasionally exceed EPA limits. But he said there's not enough data or testing about whether sidewalk de-icing is to blame. As for road surfaces, which get tons more de-icing products dumped on them, most cities and counties are keeping it old school.
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"Without a doubt, the number one chemical that we use on the roads is good old fashioned rock salt, sodium chloride," said Wilfrid A. Nixon, professor of civil and environmental engineering at the University of Iowa. "What we are trying to do is not melt the snow and ice, but stop it from melting to the road surface. The way you get it off the road is with a plow."
New additives are too expensive for most municipalities; so are heated roadways, which would eliminate the need for applying chemicals in the first place. Sand or dirt is sometimes spread on roads to provide temporary traction, although most of it is blown away by vehicle traffic, according to Nixon.