Every winter, de-icing salts — sodium chloride, calcium chloride and magnesium chloride — battle icy roads nationwide. The effort is epic in scope: Hundreds of millions of gallons of salty substances are sprayed on roads and billions of pounds of rock salt are spread on their surfaces each year. That may lead to safer roads, but it has a real effect on the planet. In a review in the journal Frontiers in Ecology and the Environment, a group of environmental scientists looked at the hazards of salts that make driving safer.
De-icing salts end up in bodies of fresh water, contaminating lakes and streams and building up in wetlands. The Environmental Protection Agency’s thresholds are not high enough to protect life in freshwater, the scientists write, and “there is also an urgent need to understand how freshwater organisms respond to novel chemical cocktails generated from road salt salinization.”
Then there’s drinking water.
When the researchers reviewed the scientific literature, they found that in many cases, drinking water salinity levels outstrip federal thresholds. The salt isn’t the only problem: Salts also increase the amount of elements such as cadmium, lead and even radium in groundwater. And because brackish drinking water can corrode plumbing, de-icing is linked to leaching of metals such as lead into the water supply in places such as Flint, Mich.
There may not be a way to end the use of de-icing salts, the researchers concede. But they say that with proper storage, mindful equipment calibration and different de-icing methods, such as pre-wetting roads or spraying salt brines before there’s ice on the ground, salts’ environmental impacts can be reduced.
One of the simplest solutions may also be the hardest to achieve. The public may need to “consider that our expectations during the winter may come at the cost of contaminating freshwater ecosystems.”
Is the public prepared to trade completely clear roads for cleaner water? It won’t be an easy choice. Either way, the “magnitude of the road salt contamination issue is substantial and requires immediate attention,” says the study’s lead author, Bill Hintz of the University of Toledo, in a news release.