How are toxic materials classified under WHMIS?
Under the Workplace Hazardous Materials Information System (WHMIS), toxic materials are part of Hazard Class D — Poisonous and Infectious Materials. Since 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 toxic material to be classified in both categories. 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. Within this division, there are two additional subdivisions that separate “Toxics” and “Very Toxics”. The “Very Toxics” are D1A; the “Toxics” are D1B. The main difference between D1A and D1B is the value used to determine acute toxicity (e.g. LD50, LC50). In simplest terms, D1A substances require much less material to produce a fatal effect. Division 2 (D2) is for “Materials Causing Other Toxic Effects”. It i
