I have heard, on a couple of occasions, but always in general news, that there was some possible serious health effects associated with the use deicing salts . I should imagine the two most common compounds used in deicing salts are sodium chloride and calcium chloride. Australian roads aren't particularly prone to snow except in our few alpine regions, so they are not used here. The nearest references to a toxic effect of a calcium salt are calcium sulfate and calcium carbonate - both classed as nuisance dusts. Without precise knowledge of the components of deicing salts, that's the limit of comment.
Human blood is quite salty.
The switch from sodium chloride to magnesium chloride was made a number of years ago due to presumed reduced corrosivity to vehicles. I'm not sure why magnesium was selected rather than calcium chloride. I also can't imagine carcinogen issues unless contaminants such as trace As, Cr, Se etc. are anticipated to be present. The Strategic Highway research program developed a series of tests for alternative deicers, these included biological tests for toxicity, particularly for wildlife, particularly in water. The thing about common salt is that its toxicity is well understood and is very low.