Research Toxicological Effects of Chloride Based Deicers in the Natural Environment

Focus Area

Water Quality/Wetlands


Natural Resources







Research Idea Scope

Recent toxicity data obtained through studies conducted by the State of Iowa and EPA Region 5 in 2009 showed that chloride was less toxic to aquatic organisms when accounting for hardness levels and the presence of sulfate in ambient waters.  EPA’s ambient aquatic life water quality criteria (EPA 440/5-88-001, 1988) for chloride needs to be revisited the criteria do not account for the seasonality of the potential chloride effects where organisms may be less susceptible to chloride toxicity during the winter period when their metabolic rates are low and feeding is at a minimum. Additional research should be conducted both in the field and/or in the laboratory to try to determine the actual effects of short and long-term exposure to various chloride levels in receiving streams.

Related Research (Added by TERI Administrator, March 2011)
Evaluation of Alternative Anti-Icing and Deicing Compounds Using Sodium Chloride and Magnesium Chloride as Baseline Deicers – Phase I; Montana State University, Bozeman, 2009, 294p

Impacts of Magnesium Chloride-Based Deicers on Roadside Vegetation; Transportation Research E-Circular, Issue E-C126, 2008, pp 171-186

Urgency and Payoff

Chloride based deicers will continue to be the primary deicing chemical of choice due to the huge cost differential with non chloride deicers.  Non-chloride deicers generally cost 15 to 20 times more than regular road salt.  There are few options for treatment or cost-effective alternatives. There has been an increasing trend of more and more water bodies being listed as impaired in the northern snowbelt States due to chloride levels exceeding the EPA’s recommended water quality standard for chloride established in 1988.  The more recent toxicological data developed by EPA Region 5 and State of Iowa suggests that chloride may not be as toxic as previously indicated in EPA’s 1988 data, particularly at the lower chronic standard used for long-term exposures.  A revision to the chloride standards, which appears warranted based on this recent data, could result in huge cost savings for many state transportation agencies by minimizing the amount of remedial measures needed to meet the chloride standard and avoid unnecessary expenditures used to mitigate for chloride related impairments that may be based on outdated data.

Suggested By

Kevin Walsh, Massachusetts Department of Transportation

[email protected]