1. it can cause excessive sweating and vomiting
2. it is a major component in acid rain
3. it can cause severe burns in its gaseous state
4. accidental inhalation can kill you
5. it contributes to erosion
6. it decreases effectiveness of automobile brakes
7. it has been found in tumors of terminal cancer patients

I guess only # 1, 3, 4, and maybe 5 would be real reasons why but still, not a good enough reason.