The harmful effects of chemical substances depend on the toxicity of the chemical and exposure to it. Toxicity is a property of the chemical substance, while exposure depends on the way the chemical is used. The level of exposure depends on the concentration of the hazardous chemical and the period of contact time. Many substances do not give any warning (by odour for example), even though they may be present at dangerous concentrations in the air.
The first and most essential step in the safe use of chemicals is to know what they are, their potential impact on health and the environment and how to control them. That knowledge should be available for all. Furthermore, that inherently complex knowledge must be organised in such a way that essential information on chemical hazards and corresponding protective measures can be identified and conveyed to the user in a form that is easy to understand.