City to avoid mag chloride despite study
The controversial de-icing agent magnesium chloride does not appear to threaten human health, according to a study released Wednesday by the Colorado Department of Health and Environment.
But that’s not stopping the city of Aspen from a tenfold increase in its de-icer budget – from $4,200 to $42,000 – so it can purchase a more benign substance.
The health department study found levels of potentially toxic heavy metals in the air often increased by the same amount when either mag chloride or the traditional mixture of sand and salt was used. It found small increases in five heavy metals – arsenic, barium, cadmium, chromium and manganese – with both de-icers, but not apparently at levels high enough to cause concern.
By analyzing filters from its air pollution monitoring equipment in Aspen and other communities around the state where magnesium chloride is applied, the department analyzed concentrations of 44 chemicals in the air on days when either mag chloride or salt and sand were applied to streets.
The study was initiated last spring, after the department started receiving complaints about mag chloride, mostly from the Roaring Fork Valley, but also from Vail and Denver.
Christopher Dann, a spokes-man for the department’s air pollution division, said the chance of experiencing health problems, including cancer, as a result of breathing air in the 24-hour period after mag chloride is applied is three in a million. That’s versus one in a million on days when concentrations of heavy metals are at normal levels.
“We cannot associate any health risk in connection with the use of magnesium chloride,” Dann said. “Sand and salt, on the other hand, has well-documented respiratory impacts on human health.”
Health problems associated with particulate matter have been studied and documented since the 1960s, leading up to adoption of the Clean Air Act in 1970. During winter, until recently, a major source of particulate matter in many communities was sand, salt and rubber ground up and kicked into the air by car tires, Dann said. Concerns remain In spite of the study’s findings, local officials remain concerned about magnesium chloride.
Aspen’s environmental health director, Lee Cassin, noted the study used a relatively small number of samples. And based on the limited amount of information from the study that Cassin has seen, she said it looks as if heavy metals were indeed more prevalent on days when mag chloride was applied.
Cassin said the city plans to replace magnesium chloride, which has been sprayed on city streets since the mid-1990s, with a de-icer known as CMAK, a mixture of calcium magnesium acetate and potassium acetate. CMAK costs about ten times as much as mag chloride, according to the Colorado Department of Transportation, and the city’s budget increase reflects that.
“It’s considered to be better for the environment than mag chloride, because it is biodegradable and does not add chlorides [salts] to the water,” she said.
Cassin also said the study did not investigate causes behind the breathing problems some people experience after inhaling mag chloride.
Carbondale resident Mary Weaver is one of those people. She was hospitalized for three days last February after being exposed to high concentrations of mag chloride while trying to wash it off her car.
Weaver said she is aware of the study, but has yet to read it and is unwilling to comment on it until she does. However, she pointed out that last fall, a spokesman from the health department said the study was not a health study, and she wondered why they were proclaiming magnesium chloride safe just a few months later.
“I personally, and other people I know, have asthmatic reactions to magnesium chloride. I never had asthma until two years ago. This is very frustrating,” she said.
Health department officials are the first to admit the study was limited in scope, simply analyzing the chemical content of the air on days the de-icers were applied.
When department officials started looking for health studies on magnesium chloride, they found that most studies had focused on its effects on the environment, with little done to determine its effects on human health.
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