[0.7] Can't mutate at toxic waste dumps

So I took robust genetics with a view to creating a freakish mutant char, but after splashing through two separate toxic dumps I haven’t even gotten sick, let alone any mutations. I have the option enabled. Are some toxic dumps not radioactive? Even so, wading through disgusting sewage should have had some effect on me. I don’t want to have to scour the world for mutagen but if I must I shall.

Edit: Nevermind, I found a geiger counter and some patches of sewage are indeed more or less radioactive than others, I managed to mutate and then shortly coughed myself to death because of smoke inhalation.