Cleaning Up Winter May be Damaging Your Health

by Isatu Crosby on March 28, 2014

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Winter Plow Clearing Snow

I think we can all agree that it has been a long, difficult winter for New England. We have weathered countless storms and blizzards in the deep of winter, and continue to experience remnants of this clear into the beginning of March. I say enough is enough, especially if city efforts to clean up these messes that winter leaves in its path can harm our environment and jeopardize our health. The U.S. Geological Survey (2009) reports that in urban streams, the highest levels of chloride were measured during winter months, approximately 20 times higher than the recommended federal quota.

With every major snowfall comes a parade of road crews clearing roads and pedestrian walkways. The most popular agent used for this job is sodium chloride, better known simply as salt. It is chemically composed of 40% sodium ions and 60% chloride ions. According to the 2008 Minerals Yearbook, the United States had been the world’s leading salt producing nation until 2005, when China surpassed the U.S. Nationwide we use more than 20 million metric tons of sodium chloride on our roads each winter, approximately 139 pounds per person. This amounts to more than 13 times more salt that the entire food processing industry uses. The salt is used to clear away snow and ice due to its efficient chemical properties. The chloride is completely soluble and easy to move around. Together the chemicals act to lower the freezing point of water to facilitate melting. Despite the ability of salt to mitigate our winter experiences with snow and ice, these public safety benefits do come at an environmental price. It is important to consider the unintended consequences of road-salt application to your drinking water supplies.

Do you ever think about what happens to the snow and ice after it has melted away and is out of your way? Until recently, I did not, and I found the answer a little disconcerting. The slush mixture created from deicing washes away from our streets and into lakes and streams or into groundwater supplies. In surface waters, salt pollution is measured based on the concentration of chloride in a given sample. The Environmental Protection Agency recommends that chloride levels remain under 230 milligrams per liter, approximately one teaspoon in five gallons of water. Chloride cannot naturally be broken down, metabolized, taken up or removed from the environment. Studies by the U.S. Geological Survey reveal that chloride levels above the recommended federal criteria have been on the climb in the U.S. as the use of road salt for deicing increases. This in part is attributable to the expansion of road networks and parking lots that need deicing, increases in discharge of wastewater, and increases in the number of septic systems. The Sources of chloride in groundwater and surface water come from different sources and can vary from one location to the nest. One of the five leading states in the production and use of salt is New York.

Salt accumulates in pockets of water underground, which has detrimental effects on well water systems. A 2008 study done in Dutchess County, New York found that 48% of 128 wells in the region averaged sodium concentration levels of 48mg/L, compared to the EPA recommendation of 20mg/L. Overall, 91% of sodium comes directly from deicing roads. The highest levels of salt concentration, 347mg/L, were found in wells in close proximity to salt storage facilities and in wells near heavily salted roads. Health officials recommend that most Americans consume 4,000mg to 6,000mg of sodium per day, or if on a sodium-restricted diet, 1,000mg to 3,00mg per day. The highest well salt concentration levels translate to consuming nearly 700mg of sodium if someone were to drink 2 liters of water from one of these high sodium wells. Considering that the majority of our salt intake should come primarily from food, this is a significant, inappropriate source of sodium for the many individuals today who struggle with hypertension.

Currently, environmental protection organizations, public health officials, and transportation officials are working in collaboration to investigate new cost-effective alternatives to road salt. In Duchess County, nearly 20% of the wells now have restrictions on the salt concentration levels that can be used by residents with high blood pressure. The majority of deicers on the market today (60-90%) are sodium chloride based, including Magic Salt® and Blizzard Wizard®. There are several alternative deicers that can be as efficient, but less damaging to both the environment and human health. Some of the chemicals that can be used in place of or to reduce salt include potassium chloride, magnesium chloride, urea, and sand. However none of these alternatives are perfect solutions. Alternatively, sometimes even simply improving the efficiency of the application process itself can contribute to decreased salt concentration levels. This can be done in many ways: using Road Weather Information Systems (RWIS) which provide real-time information about road and weather conditions to help determine the appropriate type of deicer and timing of application; retrofitting trucks with salt reducing applicator regulators; and calibrating the equipment to ensure adequate measurements. By using a combination of efforts, we can begin to improve conditions for ourselves while investing in the healthy lives of our future. Despite how far we have come, there is still a long way to go.

References
Kelly, V. R., Findlay, S. E. G.,Schlesinger, W. H., Menking, K., and Chatrchyan, A. M. (2010). Road salt: Moving toward the solution. Cary Institute of Ecosystem Studies.

New Hampshire Department of Environment Services. (2014). Environmental, health, and economic impacts of road salt. Retrieved from <http://des.nh.gov/organization/divisions/water/wmb/was/salt-reduction-initiative/impacts.htm>

PBS Newshour. (2014). Road salt keeps America’s roads safe, but threatens the environment. Retrieved from <http://www.pbs.org/newshour/rundown/road-salt-keeps-americas-roads-safe-but-threatens-wildlife-and-environment/#the-rundown>

U.S. Geological Survey [USGS]. (2009). Chloride found at levels that can harm aquatic life in urban streams of the northern U.S.–Winter deicing a major source. Retrieved from <http://www.usgs.gov/newsroom/article.asp?ID=2307#.UzYDqe-PLIU>


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