How are very toxic materials classified under WHMIS?
Under the Workplace Hazardous Materials Information System (WHMIS), very toxic materials are part of Hazard Class D — Poisonous and Infectious Materials. Since very toxic materials can cause acute (short-term) health effects as well as chronic (long-term) health effects, WHMIS has a division for each. It is possible for a very toxic material to cause both acute and chronic health effects. Division 1 (D1) contains “Materials Causing Immediate and Serious Toxic Effects”. It is represented by the WHMIS symbol to the right. As the title suggests, these materials can cause immediate and serious health effects if an exposure occurs. Within this division, there are two additional subdivisions that separate “Toxics” and “Very Toxics”. The “Very Toxics” are D1A; the “Toxics” are D1B. In this division, the primary difference between D1A and D1B is acute toxicity (e.g. LD50, LC50). D1A substances require significantly less material to produce an immediate and serious effect. Some very toxic mate
