The key to prevention of these accidents is awareness. The health effects of hazardous chemicals are often less clear than the physical hazards. Data on the health effects of chemical exposure, especially from chronic exposure, are often incomplete. When discussing the health effects of chemicals, two terms are often used interchangeably - toxicity and hazard . However, the actual meanings of these words are quite different.
Toxicity is the ability of a chemical substance to cause harm.
Hazard is the likelihood that a material will cause harm under the conditions of use . Thus, with proper handling, even highly toxic chemicals can be used safely. Conversely, less toxic chemicals can be extremely hazardous if handled improperly. The actual health risk of a chemical depends on the toxicity and the actual exposure. No matter how toxic the material may be, there is little risk involved unless it enters the body.