September 17, 2022 at 4:29 p.m.
Science of calcium chloride
I live on the little piece of Kego Township that is isolated on Broadwater Bay of Woman Lake, but I have to use Timber Dr, which is in Woodrow Township, to access our property. Timber Dr is gravel and my wife and I experience the issues and concerns with dust that Mr. Melby expressed in his letter of 20 August. I’m not sure if Timber Dr. is one of the three roads that Mr. Reher refers to in his letter of 10 September, but I do occasionally find that Timber Dr. appears wet, even though it hasn’t rained recently, and I assume that is because it has been sprayed with calcium chloride (CaCl2). This is not done as often as it could be, but my wife and I are grateful when it is done, as it does significantly reduce the amount of dust and stabilizes the surface of loose gravel, which is a safety benefit.
I can’t imagine anyone would want to experience the dust or a potential safety concern with loose gravel, so I assume, as Mr. Reher states in his 1 and 10 September replies, there are significant environmental issues that many residents of Woodrow Township feel are important enough to warrant limiting CaCl2 use. I am a retired scientists with 30+ years in the food and ag industry, during which I managed human and environmental safety studies for submission to EPA and other US regulatory agencies. Too often, in my experience, environmental advocates inappropriately use science to promote a particular position. I feel the use of CaCl2 (as well as its sister chemical, sodium chloride [NaCl], during the winter) are examples of this. Some of which I know, or can find scientific reference for, on this issue include the following:
• CaCl2 is, indeed, a nutrient and we used it regularly at the General Mills James Ford Bell Research Center. It is used in cheese making, fruit and vegetable canning and in beer brewing. Of course, no one should be directly consuming pure CaCl2 nor have the expectation that the spraying of CaCl2 on roads has any direct, human nutritional benefit.
• Virtually anything can be toxic. The old saying “the dose makes the poison” is toxicologically accurate. I would welcome any references on CaCl2’s toxicity to animals or plants to review for scientific appropriateness in this context.
• Dust that accumulates on plant leaves along gravel roadsides clearly must inhibit photosynthesis; thus, damaging them, including milkweed, which I am managing to support Monarch butterflies. I will research this point further but would welcome references from others who may have this information and I will obtain the reports noted in Mr. Melby’s letter.
• Per the letter of 1 September, I don’t know what additional knowledge the plumber has on environmental or human safety of road or softener salt (NaCl) but I would be willing to work with him understand his concerns.
• The comment, per letter of 1 September, that “salt is a cumulative contaminant problem, as once put into the environment, it doesn’t go away” is incorrect. Per the Encyclopedia of Chemical Technology, CaCl2 “is very soluble in water”, up to “30-45 wt %”, and is “extremely hygroscopic”, which is why it is useful as a wetting agent to control dust on gravel roads. If someone can give me an estimate of the total amount of CaCl2 applied on local roads, I can make a rough calculation, based on the water volume of surrounding lakes, of what the final concentration might be. This wouldn’t include normal rainfall, which would reduce the concentration further, but in either case, I’m confident it would be miniscule.
• Certainly the rusting of metals is a concern, but from my experience owning cars over the last 55 years, the automobile industry has significantly reduced salt erosion on auto surfaces.
• I’m not sure what study on ecological damage was referred to in the letter of 10 September but I had supplied “Salting our freshwater lakes” (Dugan et al 2017 PNAS) to a township official last year, noting my concern about the quality of the study and that some of its finding were not relevant locally. Quoting directly from the study, “Lakes in this dataset were not randomly sampled and thus do not necessarily represent the distribution of lakes within each state or province” and “data from Wisconsin and Minnesota are heavily biased toward urban lakes”; thus, the study selected for lakes that likely had a chloride concentration concern. There were 246 lakes in the initial dataset. In 42, the chloride concentration was decreasing, in 204 the concentration was stable, and in 125 the concentration was increasing. Again, noting the non-random and urban bias, 50% had increasing chloride concentrations. The study notes that the EPA threshold for negative impacts on aquatic life was 230 mg/liter(L) and suggests a threshold of 1 mg/L (230 times below the EPA threshold) as the point at which impacts on aquatic life might be a concern. The bottom line is, without any testing to determine what the actual chloride concentrations are in our lakes, we are limiting the use of a product that could actual have an environmental benefit and increase the quality of life, not to mention safety if we consider the use of salt in the winter on icy roads – all too common here in Minnesota.
• The letter of 10 September did raise a legitimate concern of cost. But if we had an open discussion of all the pros and cons, which I am willing to be a part of, perhaps a better understanding would make folks more willing to accept an increase in township expense.
The negative impacts humans have on the environment are real and we need to monitor and be concerned about them, but a document of importance to all Americans says we have a right to “…life, liberty and the pursuit of happiness” so we must make sure that the human and/or environmental concerns are significant enough to warrant limiting these rights.
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