Glossary / Health hazards
Acute toxicity
Acute toxicity is the adverse effect that occurs soon after a single exposure, or multiple exposures within 24 hours, to a substance by the oral, dermal or inhalation route. It is measured with values such as LD50 and LC50.
Explanation
Acute effects begin quickly, from minutes to a day or so. They range from headache and nausea to unconsciousness or death. The word describes timing and not severity: some acute effects are mild and short-lived, and others are fatal.
The UN GHS ranks acute toxicity into Categories 1 to 5 for each route, with Category 1 the most toxic; OSHA HazCom uses only Categories 1 to 4. For oral toxicity the Category 1 to 4 cutoffs are LD50 values of 5, 50, 300 and 2000 mg/kg. Categories 1 to 3 usually bring the skull and crossbones pictogram and the signal word Danger, while Category 4 brings the exclamation mark and Warning. Dermal and inhalation routes have their own cutoffs, which the SDS applies for you.
LD50 and LC50 are the usual numbers behind these categories. Lower numbers mean a smaller amount is lethal, so a low LD50 signals higher toxicity. These values come mostly from animal tests and are estimates rather than exact thresholds for people.
Acute toxicity contrasts with Chronic toxicity, which arises from long-term exposure. A chemical can be modest in one and severe in the other, so both must be read on the SDS.
What to do and watch for
- Match the route in the hazard statement, such as H301, H311 or H331, to how you might actually be exposed.
- Keep first-aid information and the poison control number available at the worksite.
- Never judge a chemical safe from a single missing symptom, as some effects are delayed.
Where it appears on an SDS
- Section 2: Hazard identification. The acute toxicity category for each route and its hazard statement and pictogram are listed here.
- Section 11: Toxicological information. Specific LD50 and LC50 values, test species and routes are reported in the acute toxicity entry.
SDS content and wording vary by supplier. This page is general reference and does not replace the current SDS for your product.