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Acute toxicity


Acute toxicity describes the adverse effects resulting from a single exposure to a substance. Under Paragraph A.1.1. of Appendix A to to 29 CFR 1910.1200, the OSHA Hazard Communication Standard (HCS 2012), acute toxicity is defined specifically as adverse effects occurring following oral or dermal administration of a single dose of a substance, or multiple doses given within 24 hours, or an inhalation exposure of 4 hours.

Additional Info

Acute Toxicity is one of the ten health hazard classifications under HCS 2012. Manufacturers are required to research the available scientific literature for data establishing acute toxicity per Paragraph A.1.2.1 of Appendix A, but are not required to perform any testing when performing the hazard classification process.

Per Paragraph A.1.2.3 of Appendix A:

The preferred test species for evaluation of acute toxicity by the oral and inhalation routes is the rat, while the rat or rabbit are preferred for evaluation of acute dermal toxicity. Test data already generated for the classification of chemicals under existing systems should be accepted when reclassifying these chemicals under the harmonized system. When experimental data for acute toxicity are available in several animal species, scientific judgment should be used in selecting the most appropriate LD50 value from among scientifically validated tests.

Human tests for acute toxicity are not performed because of ethical and legal prohibitions. The U.S. Environmental Protection Agency (EPA) describes the following methods for determination of acute toxicity:

  1. Animal testing. Animal tests are still used where other laboratory protocols are not available. These tests are combined with other assays (lethality, necroscopy etc.) to minimize the number of animals sacrificed. Evaluation of acute toxicity data should include the relationship, if any, between the exposure of animals to the test substance and the incidence and severity of all abnormalities, including behavioral and clinical abnormalities, the reversibility of observed abnormalities, gross lesions, body weight changes, effects on mortality, and any other toxic effects.

  2. Use of data from structurally related substances or mixtures. In order to minimize the need for animal testing for acute effects, the EPA encourages the review of existing acute toxicity information on chemical substances that are structurally related to the agent under investigation. In certain cases it may be possible to obtain enough information to make preliminary hazard evaluations that may reduce the need for further animal testing for acute effects.

  3. Chemical properties. For example, if a substance is a strong acid then there is really no need to do skin and eye tests as a corrosive material such as this will obviously cause great harm.

  4. In vitro testing (test tube experiments). Animal rights activists advocate such methods whenever possible. While in vitro tools have now become quite powerful, they will never be able to replace completely the need for animal studies, particularly for pharaceutical studies.

  5. Limit testing. A single group of animals, typically mice or rats, is given a large dose of the agent. If no lethality is demonstrated, no further testing is pursued and the substance is classified in a hazard category according to the dose used.

SDS Relevance

In OSHA's adoption of the GHS model, does not include the GHS's acute toxicity Category 5. This means that if the manufacturer's survey of the scientific literature (or testing, although none is required) determines that a substance meets the criteria for GHS Category 5, the acute toxicity classification of this material under the HCS would be a hazard not otherwise classified (HNOC) rather than Acute Toxicity Category 5. While the HNOC finding must be reported on the Safety Data Sheet (SDS), an HNOC finding is not one of the pieces of information that must appear on the container label (although the manufacturer is include it if they wish). This scenario is another great example of why one should always read the SDS before working with a new material - labels present only the most important hazards and precautions whereas SDS's are comprehensive.

Acute toxicity helps workers understand the health consequences from a single exposure to a chemical. For example, hydrogen cyanide is a highly toxic substance; acute exposure at relatively low doses can result in death.

Acute toxicity differs from chronic toxicity, which describes the adverse health effects from repeated (lower level) exposures to a substance over a longer period (months to years).

Further Reading

See also: Chronic toxicity, cyanide, LD50, mus (mouse), TLV

Additional definitions from Google and Onelook.

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