Magnesium Chloride - Know the Facts



Over the past few months and years, much has been printed about the use of magnesium chloride as an anti- and/or de-icer on our nation’s roads.  It has been suggested that the use of magnesium chloride has negative impacts on our environment, human health, and corrosion of cars.  In one article, however, a studied and responsible reporter from a newspaper in Glenwood Springs, Colorado reported that “There seems to be a lot of complaints and innuendoes – but very little science”.


In the spirit of that article let us strive to dispel with fiction and rumor, and replace it with fact and science.  This document will review several areas from a factual, practical, and scientific basis.  We will discuss effects on human health; on vegetation and streams; metal corrosion; and roadway safety as well as alternative methods of ice and snow control.


What is Magnesium Chloride

Let’s begin with understanding exactly what magnesium chloride is.  Simply put, magnesium chloride is “salt water”.  It is only slightly different from the salt water made from combining table salt and warm water as is often used as a gargle to remedy a sore throat.  Magnesium chloride is a naturally occurring compound that exists in the waters of the Great Salt Lake and other salt bearing aquifers deep under ground. It can additionally be found in the salt flats of Western Utah.  To harvest the product it is simply collected, allowed to purify naturally by solar evaporation and then used for its intended purpose such as to keep roads safe.


Effects on Human Health

The Colorado Department of Health (CDOH) recently undertook an extensive study to determine if airborne particulates from magnesium chloride could be detected.  The study took place in Aspen, Colorado.  Aspen was concerned about the use of the product in their community.  Complaints of severe headaches and sinus irritation were leveled at the Colorado DOT claiming the use magnesium chloride was the cause.  These complaints prompted the CDOH study, which provided conclusive results.  During the course of the study, magnesium chloride could not be detected in the air before, during, or after applications to the roadway. There were, however, minor levels of metals and other natural salts detected. The CDOH study also reported that the levels of these particulates were well within the safe or “normal” range. If the true source of these airborne metals and salts truly need to be located, perhaps the geography and geology of the region should be studied.


In other regions, there have been health complaints blamed on magnesium chloride “vapor” which is then breathed in by “unsuspecting citizens”.  This is another misconception based on speculation that is, in fact, scientifically impossible. The scientific definition of a vapor is “a substance in a gaseous state”.  Magnesium chloride is extremely hygroscopic, which is a scientific term that means “the product attracts water”.  The fact is that at normal atmospheric conditions, magnesium chloride cannot exist as a gas, it can only exist as a liquid.  It is for this reason that it is used extensively in dry weather as a dust control agent. The product remains liquid and maintains a damp road surface.  Therefore, any claims of magnesium chloride “vapor” causing ill health are best described as not only misguided but evidence of the ignorance of misinformation.  Additional blatant misinformation comes in the form of a statement made earlier this year in Montana where someone at a County Commissioners meeting stated that “magnesium chloride is a known carcinogen”.  For the record, magnesium chloride is NOT a known carcinogen.


While on the topic of air quality, let us not forget the infamous “brown cloud” that engulfed the city of Denver for a number of years.  This “cloud” can be linked to several impacts to human health as documented by a number of agencies.  Not the least of these agencies was the EPA.  The primary cause of the cloud was determined to be sand and other traction enhancing aggregates used during snow events.  The sand was ground to a fine powder by traffic and lifted into the atmosphere.  With temperature inversions, which happen naturally in the Denver geography, this fine dust remained suspended in the air that the citizens of that community had no choice but to breathe. This fine powder can be measured and was defined as “particulate matter 10 microns” (PM10). The EPA identified PM10 as a significant source of respiratory ailments. Due to the elevated levels of PM10, the EPA designated the Denver area as a “Non-Containment” area which meant they were mandated to take action to reduce the PM10 levels in the atmosphere.


The containment levels designated were met and exceeded through the use of liquid magnesium chloride in a technology known as anti-icing.  Additionally, the end result also provided a better level of service to the traveling public.  Some have suggested that perhaps we should return to the use of ordinary rock salt. It should be noted here that rock salt, or sodium chloride, is not hygroscopic.  Therefore, it can dry out on the road surface and produce a powder that is lifted into the atmosphere and contribute to air pollution, exacerbating the PM10 issues.


For some time now, complaints have surfaced of burning eyes and hands due to the use of magnesium chloride. This certainly can and does happen with repeated contact to magnesium chloride, as well as all other chloride (salt) based de-icing products. If you have any sort of perforation in your skin where the product can penetrate, you will notice a burning sensation.  If, for example, an auto mechanic uses solvents and harsh cleaners to clean the grease from his hands, they can and usually do get chapped.  This occurs because solvents and cleansers “de-fat” the skin subjecting it to dryness and leading to susceptibility of cracking especially during cold, wet weather.  When the mechanic then removes auto parts fresh in from wet winter roads, a burning sensation can occur.  That does not necessarily dictate that all complaints of skin irritation can be attributed to magnesium chloride.  Recently a mechanic in Summit County Colorado made this complaint.  It’s interesting, however, that the only magnesium chloride in the area was on Interstate 70, not the city streets. However, ordinary salt (sodium chloride) was applied along with sand to those very streets where the mechanic claimed magnesium chloride was “…not only burning my hands but ruining the cars”.


Environmental Impact

Several years ago, Dr. Bill Lewis from the University of Colorado was commissioned by the Colorado Department of Transportation (CDOT) to perform a study of the effects of magnesium chloride on the environment.  His study discovered ill effects on certain types of sensitive toads and crustaceans that are found in the Colorado high country.  These ill effects were prevalent in the laboratory at high concentrations with water.  After completing the laboratory evaluations, Dr. Lewis proceeded to the open environment to determine if the high level of contamination required to produce the ill effects to the toads and crustaceans existed in areas where magnesium chloride was being applied to the roads.  What he found was no detection of magnesium chloride what so ever beyond three feet from the edge of the road.  His study also indicated that dilution factors of up to 10,000:1, snow melt to de-icer were reasonable to expect before the de-icer left the road surface.  What is important to note here is that the tests used to approve de-icers for use on the highways in the majority of the country are 100:1, while in Colorado the products are tested using no dilution at all.  In many cases, the levels of metals or other contaminants found in drinking water are higher than those allowed in magnesium chloride de-icers.


There are also claims that the use of magnesium chloride will “burn” vegetation along the roadside. Typically, the shoulder of the road is 3 feet wide.  Dr. Lewis’ study demonstrated that magnesium chloride could not be detected beyond that distance.  Therefore, if magnesium chloride cannot be detected at that distance, how can it “burn” vegetation?  Certainly, magnesium chloride in sufficient quantities can harm plants. However, current and responsible application rates are usually around 30 gallons per lane mile, which equates to less than one ounce per square yard. At such low application rates, roadside contamination is not likely.  Consider now the fact that for many years we have applied sand to our roads to increase traction.  This sand is then thrown to the road shoulder and beyond by traffic and snow plows. This practice creates a build up of sand which is much more likely to inhibit plant growth than the magnesium chloride.


Again, some would suggest a return to standard rock salt (sodium chloride). Consider the fact that real potential for true roadside contamination exists with the use of rock salt.  Magnesium chloride is applied as a liquid in anti-icing practices.  Once applied to the road it stays there until melting snow and ice dilute it and wash it from the road surface.  Rock salt, however, is a solid that is applied in de-icing practices.  The fact that the product is dry poses two risks to the environment.  First, there have been multiple studies that demonstrate as much as 70% of the salt applied to the road is thrown to the shoulder of the road and beyond by traffic.  Second, magnesium chloride is a liquid solution that contains 30% magnesium chloride salt while the remaining 70% is water.  Rock salt is 100% sodium chloride.  Therefore, pound for pound, ordinary salt will melt far less ice and snow yet has more than three times the contamination potential.


Study after study conducted by various scientific and governmental institutions has determined that magnesium chloride does not pose a threat to the environment.  Levelton Engineering in British Columbia, one of the most water sensitive areas of our planet, has published studies extolling the safety to the environment and human health through the use of anti-icing chemicals including magnesium chloride.


The Issue of Corrosion

In the evaluation of de-icing products, agencies do indeed consider the corrosion rate of the products.  Stringent specifications have been established that require corrosion inhibitors be added before a product will be approved for use.  The industry standard for most ice melting products states that the product must be at least 70% less corrosive than standard rock salt.  The early requirements for corrosion inhibitors were primarily geared to prevent corrosion within the highway infrastructure, primarily bridges and elevated structures.  This was due to the fact that the infrastructure is expensive and difficult to replace.  Washington State has used magnesium chloride with corrosion inhibitors longer than most other agencies.  Their studies of core samples from roadway and bridges prove the positive impact of the corrosion inhibitors.  Conservatively, maintenance personnel with the state of Washington estimate from 20% to 50% increases in life expectancy of bridges due to the use of inhibited magnesium chloride.


Much has been said about corrosion to vehicles.  There have been numerous complaints regarding the cosmetic affect to chrome as well as wiring of vehicles.  First, let’s understand that the use of any chloride de-icing product (sodium, calcium, or magnesium) will increase the occurrence of rust. Yet do not forget to compare vehicles in states where corrosion inhibited magnesium chloride is used to those vehicles where rock salt is the primary product (much of the Eastern and Midwestern parts of our country).  Also, do not forget that the magnesium chloride, or any de-icing product for matter, is used to make roads safer for travel.  Washing the vehicle more often will resolve the vast majority of the vehicle corrosion issues, and this is hardly a high price to pay for safer roads and far less accidents and resultant damage claims.  With that said, the leading de-icing manufacturers are diligently working to continually improve the performance of the corrosion inhibitors.


There has also been considerable discussion regarding the impact to the environment and human health of the corrosion inhibitors themselves.  To set the record straight, most of the current corrosion inhibitors used in de-icing products are patented and proprietary.  As such, they are designed and highly engineered compounds.  In the development of such inhibitors, more consideration is given to the environmental impact of the product than the actual corrosion inhibiting performance.  In fact, most of the corrosion inhibitors used today are designed using food grade materials.  The same products you find in soft drinks, cosmetics, and shampoo, are used in the corrosion inhibitors.


In Colorado, corrosion to power lines has become a highly debated topic.  Certain power companies have complained that the use of magnesium chloride is corroding their equipment, causing power failures and even power pole fires.  None of these claims has to date been substantiated with scientific proof.  Further, some of their failures have been in locations where magnesium chloride is not being used.  On multiple occasions, individuals within the de-icing industry have stepped forward to investigate the issue and offered their assistance to these mainly small and rural power companies. Those offers have gone unanswered.


On the other side of the same coin, large power companies have indicated that the use of magnesium chloride has helped to eliminate costly air pollution which has saved them millions of dollars. These reductions in costs also should translate to lower utility bills for consumers. In spite of these facts one rural utility still complained that magnesium chloride damage to their equipment cost them $68,000.00 in one year, which was mostly in the Denver metro area.  Now consider the municipal studies that have shown that a reduction in the traffic flow of a metropolitan city due to snow and ice can cost the economy up to $ 2 Million dollars per hour.  If the magnesium chloride is truly the cause of the equipment failures as the power companies contend, perhaps they should still consider the larger issue at hand.


Roadway Safety

The City of Denver, the Colorado DOT, the State of Idaho and many other agencies have studied the positive effects of magnesium chloride on road safety.  In areas where magnesium chloride is used, it has been documented by these agencies that up to 70% fewer accidents occur.  These are not isolated cases.  The Insurance Corporation of British Columbia (ICBC) has conducted several studies into accidents, fatalities, and accident claims.  The most recent study showed that through the use of an anti-icing program, snow and ice related crashes were being reduced.  To quote the report, “The anti-icing program appears to be contributing to a steadily decreasing wintertime snow and ice day crash related claims rate in the Kamloops area.  Kamloops has experienced a 40% reduction in overall claims related to snow and ice road conditions.”  Such dramatic improvements are the result of a proactive maintenance plan that includes anti-icing practices using, among other products, magnesium chloride.   Money saved, and certainly, lives saved was the conclusion reached through practices that included the use of magnesium chloride.


What are the alternatives?

Magnesium chloride is not the only product on the market.  There is rock salt, sand, salt and sand mixtures, calcium chloride, various non-chlorides and others.  Again and again misinformed opponents to magnesium chloride ask “Why not just go back to sand or salt?  Sand, as demonstrated above can pose a significant threat to human health in urban environments.  Further, environmentalists have stated that due to siltation, sand is perhaps more detrimental to aquatic life than even rock salt.  Many studies have shown that the sand removed from streets and roadways contains elevated levels of lead presenting problems of disposal of a potentially hazard waste.  In regard to salt, one of the things the scientific community knows for sure is that salt is detrimental to the environment.  In fact, as discussed above the Canadian Ministry of the Environment is currently investigating salt and it is expected that they could list salt as one of the substances that would be considered CEPA toxic.  Additionally, as demonstrated above it can also pose a human health risk in urban environments as well as contaminating drinking wells, which has been well documented in the Eastern US.


There are non-chlorides products available that are exceptionally safe and even less corrosive than water.  However, these products are expensive (as much as 7-8 times as expensive as magnesium chloride) and agency budgets continue to shrink.  Additionally, some of the non-chlorides are not nearly as effective as magnesium chloride and therefore not practical for wide application.


It has been suggested in the press that highway agency management is arrogant and even “stupid”.  We submit that the managers and workers of our transportation departments and the city street maintenance agencies are neither arrogant nor stupid but prudent civil servants doing a thankless job and doing it well.  They have studied all of the alternatives and have made rational decisions based on fact and scientific data.  Our economy benefits and our streets stay clear and safe.  Our civil servants are doing this with fewer and fewer resources.  We owe them a vote of thanks, not unfounded criticism.  If the majority of the citizens will rationally consider the facts and the science that goes into the decisions by the road maintenance agencies, they will undoubtedly offer their support and thanks to those agencies.


Thank you for your kind patience and consideration.


In the development of this document, studies conducted by the following agencies were consulted:

1. Dr. Bill Lewis Study, University of Colorado

2. USEPA Clean Water Act and Resource Conservation and Recovery Act

3. Levelton Engineering Report on the Environmental Impact of De-icing Chemicals

4. OSHA Dermatitis Study of Factory Workers

5. Various studies conducted by MnDOT, CDOT, WSDOT, IDOT

6. Dale Keep, Washington State DOT (Retired)

7. Marion Fischel – Sea Crest Group

8. ICBC report:  Evaluation of the Southern Interior Anti-icing Programs.