Some people say the dangers of mold are highly overrated. They are the lucky ones. Maybe they are the ones who are unaffected. Just as some people do not have hayfever, some people do not have sensitivity to the kinds of mold that cause an allergic reaction in people. As for other molds which produce known toxins, those molds are known to be toxigenic across the board. Those are the molds that create toxins, called mycotoxins.
Mycotoxins vary greatly in their severity, depending on the fungus creating them, and the victim infected and his or her susceptibility. The most studied mycotoxins are those which affect crops. The ones that affect housing have not been as well studied. But regardless how well they are studied, mycotoxins can cause serious illnesses in the field, in crops, and in homes and offices, or anywhere the mold can find moisture and ingest cellulose.
Some estimate that half the buildings in the United States contain some sort of mold and water damage; this is an alarming statistic when more than a quarter of the population is genetically sensitive to mold toxins.
Read the toxic effects of mycotoxins in humans.