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.
Symbol - Materials Causing Immediate and Serious Toxic 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. 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.
Symbol - Materials Causing Other Toxic Effects
Division 2 (D2) is for "Materials Causing Other Toxic Effects". It is represented by the WHMIS symbol to the right. These materials have toxic effects but these effects may be delayed. The D2 division also has two subdivisions that separate "Toxics" and "Very Toxics". The "Very Toxics" are D2A; the "Toxics" are D2B. The "Toxic" group here also includes products that produce immediate but less serious reversible effects.
Under the D2A heading of "Materials Causing Other Toxic Effects", the health effects considered for very toxic materials (D2A) include:
severe chronic toxic effects
reproductive toxicity (material known or suspected to cause a negative impact on reproductive functions (male or female)
teratogenicity and embryotoxicity (material known or suspected to cause a negative impact on a developing embryo or fetus)
carcinogenicity (material known or suspected to cause cancer)
respiratory sensitization
Under the D2 heading of "Materials Causing Other Toxic Effects", the health effects considered for toxic materials (D2B) include:
chronic toxic effects
skin or eye irritation
skin sensitization
mutagenicity (material known or suspected to cause changes to cells)