Overview
ISO 29200:2013 - "Soil quality - Assessment of genotoxic effects on higher plants - Vicia faba micronucleus test" describes a standardized in vivo method to detect genotoxicity in soils and soil materials using the secondary roots of Vicia faba (broad bean). The test identifies micronuclei in root tip cells caused by chromosome breakage (clastogenicity) or mitotic spindle dysfunction (aneugenicity). Two exposure routes are covered: direct exposure to soil/material and exposure to water extracts (leachates/eluates) to detect mobile mutagens transferable to aquatic compartments.
Key topics and technical requirements
- Test organism: Vicia faba (broad bean), seeds free of pesticide coatings; secondary roots are examined.
- Endpoints measured: micronucleus frequency and mitotic index; statistical analysis to determine significance.
- Exposure modes:
- Direct contact with sieved soil/material (samples sieved to 4 mm; moisture ~70% of water-holding capacity).
- Aqueous exposure using leachates/eluates prepared per ISO/TS 21268 series (eluates decanted, not filtered; tests within 24 h).
- Controls and reference: negative (Hoagland’s medium or control soil) and positive control using a reference substance (maleic hydrazide is recommended; the standard specifies control conditions).
- Laboratory setup & equipment:
- Plastic pots for soil exposure and glass beakers for liquid exposure.
- Microscope capable of ×400 magnification for scoring micronuclei.
- Reagents and sample handling:
- Carnoy’s solution, HCl hydrolysis, DNA staining (e.g., orcein in acetic acid) and Hoagland’s medium (composition given in annex).
- Sample storage guidance: short-term dark storage at ~4 °C to minimise volatilisation and sorption losses.
- Quality criteria: defined validity criteria, sample characterisation (texture, pH, organic matter, cation exchange capacity, water content) and recommended control soil matching.
Applications and users
ISO 29200:2013 is practical for:
- Environmental laboratories performing soil genotoxicity testing.
- Regulatory agencies assessing contaminated sites, remediation outcomes and waste/compost/sludge safety.
- Ecotoxicologists and soil scientists evaluating mutagenic risk to terrestrial plants and potential transfer to aquatic systems through leachates.
- Industry and consultants conducting environmental impact assessments or monitoring effluents and treated soils.
Benefits include detecting genotoxic agents not readily revealed by chemical analysis or conventional ecotoxicity tests and providing standardized, comparable results for risk assessment.
Related standards
Normative and complementary references include:
Keywords: ISO 29200:2013, Vicia faba micronucleus test, soil quality, genotoxicity testing, micronucleus, leachate, eluate, Hoagland’s medium, soil ecotoxicology.