Indicators of toxicity hazards include LD ₅₀, LC ₅₀, plus a wide range of in vitro and in vivo techniques for assessment of skin and eye irritation, skin sensitization, mutagenicity, acute and chronic dermal and inhalation toxicity, reproductive toxicology, carcinogenicity etc.

The LD ₅₀ is the statistically derived single dosage of a substance that can be expected to cause death in 50% of the sample population. It is therefore an indicator of acute toxicity, usually determined by ingestion using rats or mice, although other animals may be used. LD ₅₀ is also determined by other routes, e.g. by skin absorption in rabbits. The values are affected by species, sex, age, etc.

The LC ₅₀ is the lethal concentration of chemical (e.g. in air or water) that will cause the death of 50% of the sample population. This is most appropriate as an indicator of the acute toxicity of chemicals in air breathed (or in water, for aquatic organisms). Table 5.11 illustrates the use of LD ₅₀ values to rank the toxicity of substances.