Review on the Toxicological Effects of Chloride-Based Deicers: Impacted Environments and Assessment Methods

With the growing reliance on chloride-based deicers in winter roadway maintenance operations, the concerns over their adverse impacts have been highlighted in recent years, especially the direct stress that applied chemicals bring to the receiving roadside soil, water bodies, aquatic biota, and vegetation through snowmelt runoff, infiltration and wind blow. This work started from synthesizing current knowledge on the negative/toxicological effect of chloride-based snow and ice control products to the natural ecosystem, and then put an emphasis on the examination of typical methods used to assess the toxicity of chloride-based deicers on the water quality and aquatic biota in the laboratory and field tests. The summary focused on the species to test, calculation process, and influential factors in the laboratory test, followed by the field sample collection options, timing of sampling, key variables and bio-assessments in the field test to quantify toxicological effects of chloride-based chemicals. Finally, efforts on current theoretical research and the need for further work (e.g., field monitoring and bio-assessments or bio-monitoring over time, the effective correlation between laboratory toxicity data with field data, and the relationship among key variables and resulting toxicity index) were discussed.