I am still trying to get up to speed on ice-melting compounds. So far, two things appear crystal clear.
First, rock salt — sodium chloride, NaCl, halite — is the worst ice-melting compound, in terms of metal and concrete damage, environmental harm, and pet safety.
Second, most of the claims, made by most ice melters, are, at best, exaggerations.
Pet-safer: Crossing the line on exaggerated product claims.
But some ice-melter claims — particularly regarding “pet-safe” and “eco-friendly” — are purposefully deceptive.
And, oddly enough, those purposefully-deceptive claims of “pet-safe” and “eco-friendly” ice melts work exactly the same way. In order to be legal, they only claim to be pet-safer or eco-friendlier. Than what, you might ask? Than pure rock salt. So the first takeaway is that anything that’s even trivially better than pure rock salt — such as rock salt with some tiny amount of additives — can advertise itself as both “pet-safer” and “eco-friendlier” (…. than rock salt).
Surely we agree that rock salt is not pet safe?
By way of making this as clear as possible, let me narrow it to dogs. And focus on the bottom of the barrel — rock salt.
A dog will get sick if it ingests too much (table, NaCl) salt. One reference listed a dog-lethal dose of sodium chloride (salt) as 4 grams per kilogram body weight (Source: Veterinary Toxicology, 4th Edition.) Thus a 30-pound dog that manages to eat two ounces of rock salt, and keep it down, might reasonably die from doing that. (That’s about three level tablespoons of table salt.)
And a dog could pretty clearly get sick from a lower dose than that. Salt poisoning leads to vomiting, diarrhea, and, if it proceeds far enough, to neurological symptoms (e.g., inability to walk).
Salt poisoning of dogs does not appear to be very common. Another reference said that in 1998, there were just 50 such cases reported to ASPCA poison control hot line. Currently, salt poisoning doesn’t make the top 10 list of common pet poisons.
And, from reading a few case reports, ice-melt poisoning can occur if a dog takes a big gulp of the stuff, straight out of the bag. But, in general, that’s not the problem being addressed by use of “pet-safe” de-icers. A mouthful of de-icer is going to be bad for your pet, no matter what.
Instead, people who buy pet-safe ice melt are worried about dogs walking on areas treated with (e.g.) rock salt as an ice-melter. First, salt irritates dogs’ paws. And second, dogs ingest salt from licking off salt crystals stuck on or in their paws,
The upshot of all that is that rock salt (NaCl) is something you don’t want to see in a “pet-safe” ice melt.
So what do I find, off the crack of the bat, on the Home Depot website?
And that’s not a one-off accident. Here’s the same nonsense from Uline, a supplier of industrial products of all types:
So …
Once you move beyond colored rock salt — clearly not pet-safe — there’s some real ambiguity as to what’s safe or not.
Urea is typically considered fully safe for dogs and cats (but is not safe for ruminants). But urea is basically high-potency nitrogen fertilizer.
I can’t see myself dumping a 50-pound bag of 43-0-0 fertilizer on the driveway in winter. Or in any season, really.
Plus, it’s a poor ice melter, and you’d be hard-pressed to find it bagged in bulk for consumer ice-melt use. Apparently, it is only commonly used in specialty situations such as elevated metal walkways, where lack of metal corrosion is the key concern for the ice-melt.
Acetate ice melters (calcium magnesium acetate (CMA) and potassium acetate (KAC)) are considered pet-safe by some. But these, too, perform relatively poorly as ice-melters, and are expensive per effective melting dose, as well. They have the additional advantage of not being chloride salts, and so being less toxic to the aquatic environment than (say) rock salt.
Beware “with CMA”, just as you should beware pet friendlier. A lot of ice-melt blends want to bask in the glow of CMA without the bother and expense of actually including much of it in their blend. (Plus, the ice melter probably works better as an ice melter if you go light on the CMA, because CMA apparently is not a very good ice melter. It just has the big advantage of killing less stuff than chloride salts do.)
Magnesium chloride is considered safer for pets than other chloride salts. It is sold, for example, by both PetSmart and PetCo as a pet-safer de-icer. It also performs quite well as a de-icer. From a pet-safety standpoint, the only drawback appears to be price. In retail packaging, MgCl2 appears to cost anywhere from five to ten times as much as rock salt. But, as a chloride salt, this is not materially better than rock salt, from the standpoint of toxicity to the aquatic environment. And some references suggest that it causes more damage to concrete than rock salt does, particular to newer (under-one-year-old) concrete.
Conclusion
I have no dog in this fight, if you will excuse the phrase. I don’t own a pet, so this isn’t my problem. I only stumbled across it in looking for ice melts that aren’t chloride salts, hoping for lower environmental impact. And was vaguely outraged once I figured the whole pet-friendlier thing as discussed above.
But I note that it is a common and accepted practice in the ice-melt market to take a bag of common rock salt, color it (green or blue, inevitably), sprinkle in some actually pet-safe materials, slap “pet-safer” on the bag, and then double the amount charged for it.
Unlike pet food, nobody appears to regulate anything about “pet-safer” de-icers. Even though the danger arises from pets eating the stuff. Contrast that the the multi-agency Federal regulation of pet food. (Not that the Feds need to regulate de-icers per se, but the use of “pet-safer” and similar legal-but-misleading claims.)
Unsurprisingly, then, a lot of stuff offered in the big-box hardware stores as “pet-safer” ice melt is just rock salt (plus a tiny amount of additives) sold at a steep markup.
Caveat emptor.
