toxicity category rating toxicity category rating in 40 cfr 156.62, the epa established four toxicity categories for acute hazards of pesticide products, with "category i" being the highest toxicity category (toxicity class). most human hazard, precautionary statements, and human personal protective equipment statements are based upon the toxicity category of the pesticide product as sold or distributed. in addition, toxicity categories may be used for regulatory purposes other than labeling, such as classification for restricted use and requirements for child-resistant packaging. in certain cases, statements based upon the toxicity category of the product as diluted for use are also permitted. a toxicity category is assigned for each of five types of acute exposure, as specified in the table below. overview the four toxicity categories, from one to four are: toxicity category i is highly toxic and severely irritating, toxicity category ii is moderately toxic and moderately irritating, toxicity category iii is slightly toxic and slightly irritating, toxicity category iv is practically non-toxic and not an irritant. acute toxicity categories for pesticide products in the following table, the leftmost column lists the route of administration. i ii iii iv oral ld50 up to and including 50 mg/kg from 50 to 500 mg/kg from 500 to 5000 mg/kg greater than 5000 mg/kg inhalation lc50 up to and including 0.2 mg/l from 0.2 to 2 mg/l from 2. to 20 mg/l greater than 20 mg/l dermal ld50 up to and including 200 mg/kg from 200 to 2000 mg/kg from 2000 to 20,000 mg/kg greater than 20,000 mg/kg eye effects corrosive; corneal opacity not reversible within 7 days corneal opacity reversible within 7 days; irritation persisting for 7 days no corneal opacity; irritation reversible within 7 days no irritation. skin effects corrosive severe irritation at 72 hours moderate irritation at 72 hours mild or slight irritation at 72 hours