Overview
ISO 20963:2005 - Soil quality - Effects of pollutants on insect larvae (Oxythyrea funesta) - Determination of acute toxicity describes a standardized laboratory method to assess acute toxicity of contaminated soils and chemical substances to the larvae of the scarab beetle Oxythyrea funesta. The test exposes third‑instar larvae to pollutants by cuticular and alimentary uptake and measures mortality after a 10‑day exposure. The method is designed for soil quality assessment, ecotoxicology and environmental monitoring of soil pollution.
Key topics and technical requirements
- Test organism: Oxythyrea funesta, third‑instar larvae (fresh mass 100–200 mg); within‑container mass range must not differ by more than 50 mg.
- Exposure routes: Cuticular and alimentary uptake from contaminated soil or artificial soil substrate.
- Test conditions: Temperature (26 ± 1) °C, complete darkness; test mixtures prepared at start and not renewed.
- Duration and endpoints: Mortality recorded after 10 days to determine LC50 (median lethal concentration). Growth (mass increase) may be measured as an optional complementary endpoint.
- Test design: Two‑step approach - preliminary range‑finding (no replication) and definitive test (at least five concentrations, geometric progression, three replicates per concentration). Ratio between consecutive concentrations should not exceed 2.
- Substrates: For substances, a defined artificial soil (70% quartz sand, 20% kaolinite clay, 10% sphagnum peat; CaCO3 added to reach pH 6.0 ± 0.5) with 300 g dry mass per test container. For contaminated soils, either comparable uncontaminated soil or artificial soil may be used as control/dilution substrate.
- Limitations: Not applicable to volatile substances (Henry’s constant or air/water partition coefficient > 1, or vapour pressure > 0.00133 Pa at 25 °C). The method does not account for substance degradation during the test.
- Reference substance: 2,4,5‑trichlorophenol (analytical grade) suggested for performance checks.
- Quality requirements: pH and water‑holding capacity must be measured (referenced ISO standards), replicate numbers and concentration ranges specified for statistical LCx estimation.
Applications and users
- Environmental testing laboratories conducting soil ecotoxicity tests and screening of contaminated sites.
- Regulatory agencies and risk assessors evaluating soil pollution impacts on soil invertebrates.
- Remediation consultants and environmental consultants assessing acute toxicity of soils or amendments.
- Pesticide and chemical safety assessors requiring standardized methods for soil organism toxicity.
Practical value: ISO 20963:2005 provides a reproducible test for LC50 estimation and comparative toxicity screening, aiding decision‑making in site assessment, remediation prioritization and regulatory compliance.
Related standards
Keywords: ISO 20963:2005, soil quality, Oxythyrea funesta, acute toxicity, LC50, soil ecotoxicology, artificial soil, soil pollution, environmental monitoring.