a germ is a kind of harmful substance
germ is microorganism. toxic_substance is biochemically_harmful_substance. biochemically_harmful_substance is not dangerous_thing. biochemically_harmful_substance is dangerous_thing. chemically_harmful_substance is not biochemically_harmful_substance. radioactive_substance is biochemically_harmful_substance. aerosol is biochemically_harmful_substance. radioactive_substance is not biochemically_harmful_substance. germ is not microorganism. chemically_harmful_substance is biochemically_harmful_substance.