I found the MSDS on the only ingredient listed on the can and it seems sort of ok. Whatever the other ingredients are is a mystery.
Ammonium phosphate and potassium nitrate are generally considered to have low toxicity by all routes of exposure. Ingestion of these chemicals may also cause nausea and vomiting with irritation to the mouth, throat, esophagus, and stomach. High concentrations of dusts or mists may cause upper respiratory tract irritation with coughing and nasal discharge.