Objective of the study

The 90-day inhalation toxicity test is used to characterize the toxicity of a pesticide by the inhalation route for a sub-chronic duration (90 days), and to provide robust data for quantitative inhalation risk assessments.

Sub-chronic inhalation toxicity studies are primarily used to derive regulatory concentrations for assessing operator and worker risk in occupational settings. They are also used to assess human residential risk.

Circumstances under which the study is recommended to be required

The 90-day inhalation toxicity study may be required if there is a likelihood of significant repeated inhalation exposure to the pesticide as a gas, vapour, aerosol or small particulate.

The decision whether to conduct a 90-day inhalation toxicity study should be made based on the basis of expert opinion, after initial consideration of acute inhalation toxicity data.

Depending on estimates of the magnitude and duration of human exposure, studies of shorter duration, e.g. 21 or 28 days, may be sufficient to satisfy this requirement.

Test organism

The study is normally conducted with rats. If another mammalian species is used, the applicant should provide a justification for its selection.

Test substance

- Technical grade active ingredient

Typical endpoints of the study

Typical endpoints include mortality, haematology and clinical pathology, as well as ophthalmology, gross pathology, organ weights, and histopathology.

Where possible, the No Observed Adverse Effect Level (NOAEL) will be reported.

Test guidelines

The following test guidelines may be used for the short-term inhalation toxicity studies:
• OECD Guidelines for the Testing of Chemicals. Test No. 413: Subchronic inhalation toxicity: 90-day study.
• OECD Guidelines for the Testing of Chemicals. Test No. 412: Subchronic inhalation toxicity: 28-day study.
• US EPA Health Effects Test Guidelines. OPPTS 870.3465. 90-day inhalation toxicity.
• EC Testing Method B.29 Sub-chronic inhalation toxicity study 90-day repeated inhalation dose study using rodent species. Council Regulation (EC) No 440/2008.
• EC Testing Method B.8 Repeated dose (28 days) toxicity (inhalation). Council Regulation (EC) No 440/2008.