Glossary / Health hazards
Chronic toxicity
Chronic toxicity refers to harmful effects that develop after prolonged or repeated exposure to a substance, often over months or years. Exposures may be too low to cause any immediate symptoms.
Explanation
Chronic harm builds slowly. A worker may feel fine for years while a chemical gradually injures the liver, kidneys, nerves or lungs, or while cancer risk quietly rises. Because there are no early warnings, relying on how you feel is a poor safety check.
The GHS has no single class called chronic toxicity. Instead, long-term effects are captured by several: specific target organ toxicity after repeated exposure, carcinogenicity, germ cell mutagenicity, and reproductive toxicity. In the environment, chronic aquatic hazards are classed separately. The H372 and H373 statements are common signs of chronic organ effects.
Occupational exposure limits exist largely because of chronic effects. A time-weighted average aims to keep the average daily dose below levels linked to harm over a working lifetime. Studies that find a NOAEL in long-term animal tests are an important basis for those limits.
Some chemicals accumulate in the body, so each exposure adds to the last. Others cause damage that is not reversible, so recovery after stopping is limited. These features make prevention and measurement far more valuable than treatment.
What to do and watch for
- Compare air monitoring results with the applicable exposure limit, not with your sense of smell.
- Join any medical surveillance program offered for the chemicals you work with.
- Keep control measures in place even when a task seems to cause no problems.
Where it appears on an SDS
- Section 11: Toxicological information. Long-term effects, such as repeated-dose organ damage, cancer and reproductive findings, are described here.
- Section 8: Exposure controls / personal protection. Exposure limits, designed largely to prevent chronic harm, and recommended controls are listed in this section.
SDS content and wording vary by supplier. This page is general reference and does not replace the current SDS for your product.