First....good lord, please never ever...ever store chemicals near your food. That is just retarded.
It might also only be -17 where the thermometers are, not all over. Also, what kind of container is it in, as it could be fairly well insulated making it take longer.
It could be contaminated, but why are you asking us what with? Did you make it yourself, or did you buy it? If you made it your self, obviously the method of production will give clues on what it might be contaminated with.
Also, did I mention how utterly stupid it is to store chemicals near your food? You do realize that bromine is very toxic to humans, and inhaling or digest any can cause serious damage and even death?