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  • Writer's picturejtanu071

Rock Salt vs Ethylene Glycol: The Price we Pay for Cheap De-Icing

Author: Niharika Namulla, Environmental Assessment Analyst, PhD. in Environment and Sustainability


Impacts of Rock Salt on the Environment

Rock salt has a wide range of distressing impacts on wildlife, plants, water and soil (1):

Chloride:

  • completely soluble and mobile.

  • Toxic to aquatic life, impacts on vegetation and wildlife.

  • No natural process to break down, metabolize, or remove from environment(2)

Sodium:

  • can alter soil chemistry- replace and release nutrients into groundwater/surface water- impacting aquatic life.

  • contamination to drinking water (concern for low-sodium restricted diet of individuals)(2)

Fresh water bodies far from urban centers can be impacted too(3)

In some urban streams, salt is high enough to kill, but lower levels can be very lethal as well

At moderate levels salt can cause decreased reproduction in amphibians, plant browning, and lower nutrient availability for plants and animals, increase in unwanted invasive species.


Dense salt water sinks --> threat to deep cold water fish


Most visible impact on grass, shrubs and terrestrial roadside vegetation which can also impact submerged aquatic plants eventually



Environment Canada considered adding this substance to the country's most toxic substances(1)


A recent study (Dugan et al., 2017) found that at least 7,770 lakes in North America are at risk from salinization due to road salt(3)

Impacts of Ethylene Glycol on the Environment(4)

Ethylene glycol can also have certain negative impacts on people and animals- along with toxic effects in streams, rivers and other bodies of water. The direct comparison of exposure concentrations along with no-effect values (ENEVs) suggests that adverse effects are unlikely when consideration is given to the seasonal nature of releases, ambient temperatures, metabolic rates and duration of exposure. Indirect effects through oxygen depletion low potential for concentrations of dissolved oxygen (DO) to drop to levels of concern.


For the year 2005, scheduled air transportation and support activities for air transport account for 95% of untreated releases to land.


Ethylene glycol has been found to biodegrade rapidly in the aquatic environment and therefore has the potential to induce depletion of the dissolved oxygen (DO) in receiving waters.

However, it is proposed that ethylene glycol is not entering the environment in a quantity or concentration or under conditions that have or may have an immediate or long-term harmful effect on the environment. The SoS Report revealed that, once released into the environment, ethylene glycol partitions mainly into surface water or groundwater.


Ethylene glycol does not bio-accumulate or persist in the environment, primarily due to biodegradation.


Furthermore, the substance has a low inherent toxicity (adverse effects in organisms only at relatively high doses or concentrations). Half-life: 0.35 to 3.5 days in air, 2 to 12 days in water (4) to 24 days in groundwater and 2 to 12 days in soil(4).


IN CONCLUSION

Ethylene glycol would be an acceptable replacement for rock salt considering the significantly lower impacts of ethylene glycol on the environment as well as the human health. Any initial start up costs in manufacturing and start-up of ethylene glycol will be replaced with increased savings from decrease in environmental repair and damage control as would be necessary for rock salt.


REFERENCES:

  1. Russell, A. (2017, January 11). Why do we still use road salt and what are the alternatives? Retrieved March 10, 2018, from https://globalnews.ca/news/3174300/why-do-we-still-use-road-salt-and-what-are-the-alternatives/

  2. New Hampshire Department of Environmental Services. (n.d). Environmental, Health and Economic Impacts of Road Salt. Retrieved from https://www.des.nh.gov/organization/divisions/water/wmb/was/salt-reduction-initiative/impacts.htm

  3. International Institute for Sustainable Development. (2017). Costs of Pollution in Canada. Retrieved from https://www.iisd.org/sites/default/files/publications/costs-of-pollution-in-canada.pdf

  4. Health Canada, Priority Substances List Assessment report (2007). Retrieved from https://www.ec.gc.ca/lcpe-cepa/documents/substances/eg/eg_draft-eng.pdf

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1 Comment

Stuart Tait
Stuart Tait
Mar 26, 2018

Very simple to understand, and the pictures are easy to follow. I hope Ottawa makes the right decision in choosing Ethylene Glycol because the environment is a resource we can't risk losing or destroying!

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