A corrosive substance that either causes full-thickness destruction after exposure between 60 minutes and 4 hours, or does not cause full-thickness destruction but has a corrosion rate exceeding 6.25 mm per year at 55°C, belongs to which packaging group?

• A. Class 8 Packing Group 2
• B. Class 9
• C. Class 8 Packing Group 3
• D. Class 7

Answer: (C)

Class 8 packing groups are about how corrosive a substance is and how it might affect packaging materials. The two criteria given—whether exposure to the substance causes full-thickness destruction of skin within a defined time window, and the corrosion rate on metal at 55°C—are the standard thresholds used to assign packaging groups for corrosives. If either criterion places the substance within the defined limits for the lower-hazard end of the corrosives, it falls into Packing Group 3. In this scenario, the described conditions map to that group, meaning the substance is treated as a PG III corrosive, which requires less stringent packaging than the more dangerous PG I or PG II options.