ISO 21427-2:2006

Overview

ISO 21427-2:2006 - "Water quality - Evaluation of genotoxicity by measurement of the induction of micronuclei - Part 2: Mixed population method using the cell line V79" - specifies an in vitro micronucleus test for assessing genotoxicity of water and wastewater. The method detects chromosomal damage (clastogenicity) and spindle/segregation effects (aneugenicity) in V79 mammalian cells (Chinese hamster lung cell line) by measuring the increase in micronucleated cells after exposure to test samples, with and without metabolic activation (S9 mix).

Key topics

• Test principle: Compare frequency of micronucleated cells in treated cultures vs negative controls to identify substances causing chromosome fragments or whole-chromosome loss that appear as micronuclei.
• Cell system: Use V79 cell line with documented karyotype, plating efficiency and controlled culture conditions (37 °C, 5% CO2). Preserve stock cultures in liquid nitrogen.
• Exposure conditions: Typical exposure is 24 h (or 4 h when using S9 metabolic activation), followed by slide preparation, staining (Giemsa) and scoring.
• Metabolic activation: Use an S9 fraction (induced rat liver supernatant) and cofactor solution (S9 mix) to simulate in vivo metabolism. S9 must be prepared or sourced in accordance with Annex C.
• Quality controls: Positive controls (e.g., cyclophosphamide, EMS), negative control, and monitoring of cytotoxicity, pH and osmolality to avoid false positives caused by secondary effects or precipitation.
• Reagents & media: MEM medium, fetal bovine serum, antibiotics, fixation and staining solutions, and reagents for hypotonic treatment are specified.
• Evaluation & reporting: Criteria for D values (dilution levels), proliferation/mitotic indices, survival index and precision data are included.

Applications

• Environmental and water quality testing laboratories assessing genotoxic potential of surface water, groundwater, drinking water and wastewater.
• Regulatory monitoring programs and risk assessment workflows where identification of genotoxic agents from water-soluble fractions is required.
• Research labs studying mechanisms of waterborne genotoxicity or evaluating treatment process efficacy in removing genotoxic contaminants.

Who uses it

• Accredited environmental testing labs
• Public health and regulatory agencies
• Wastewater treatment operators and consultants
• Academic and toxicology research groups

Related standards

• ISO 21427-1 - evaluation using amphibian larvae (companion part)
• ISO 5667-16 - guidance on sampling for biotesting of water and wastewater

Keywords: ISO 21427-2:2006, water quality, genotoxicity, micronucleus test, V79 cell line, in vitro, S9 mix, micronuclei, water and wastewater testing.