Road crews are spreading salt on many East Coast highways as a big winter storm prepares to slam into the region Friday morning, but the same de-icing salt that may prevent accidents could also be poisoning drinking water in many U.S. communities, scientists say.
In Flint, Mich., for example, thousands of families have suffered health effects from high amounts of lead in their drinking water -- from skin rashes to possible brain damage in children. President Obama declared Flint a disaster area this month, and Michigan's governor apologized to local residents on Tuesday, saying he would spend $28 million to fix the water problems.
While many residents are angry at the people who ran the city's water supply, as well as state and federal regulators who residents say ignored the problem for almost two years, there may be an additional culprit: road salt. Researchers believe that high levels of chloride from salt corrodes the pipes and can dislodge lead particles into the water that flows into our homes.
"We are essentially salting our earth," said Marc Edwards, professor of water engineering at Virginia Tech, who has been studying the effects of salt corrosion on lead found in water pipes in Flint, Washington, D.C. and New Jersey.
"We are putting 130 pounds per person on the roads each year in the U.S. and it's already doubled the level of salt in many U.S. rivers," he told Discovery News. "The potential consequences of this are quite extraordinary."
According to a recent study by the U.S. Geological Survey, the amount of road salt used on the nation's roads doubled from 1990 to 2011, while salt levels in northern streams has risen faster than the rate of normal urbanization.
In 2015, the National Science Foundation gave Edward a $50,000 grant to investigate Flint's water distribution system. He found that chloride concentrations in the city's drinking water had soared from 11.4 mg/l to 92 mg/l after city officials switched from the Detroit River to the Flint River.
Edward said high chloride levels corrode plumbing infrastructure, causing lead particles to separate from the pipe and leach into the water.
"Salt can serve as a trigger for lead leaching," he said. "We are researching this now. This really escaped my radar until these events."
It's not just Flint. Brick, N.J., residents have been warned about high lead in their drinking water for the past two years. Officials believe the problem may have come from saltwater intrusion from Hurricane Sandy that is corroding lead soldering in pipes from homes built before 1987, according to Edwards.
While some cities and towns are trying to cut back on the use of salt because of problems with public health and the environment, it's still the most popular way to clear snow and ice from asphalt surfaces. Some alternatives have emerged, like mixing a brine of water and salt with carbohydrates like extracts from beets, wine, beer or cheese to make the mixture stick to the road surface.
"The salt you put on the road stays on the road longer" with these carbohydrate-based extracts, said Wilfrid Nixon, vice president of science and the environment at the Salt Institute, a non-profit industry trade group based in Alexandria, Va. "The longer it's on the road, the more good it's going to do you before it gets into the environment."
Nixon says the only states that do not stockpile road salt for the winter are Louisiana, Alabama and Florida. He said reducing the use of road salt means more training, bigger storage areas and new highway equipment that can apply the mixtures. These improvements aren't always possible for local governments facing tight budgets.
"There are more and more people just trying to be as efficient as they can," Nixon said. "Because the winter maintenance budget fairy isn't handing out any more money."