Overview
EN ISO 18187:2024 - Soil quality specifies a rapid contact test for solid samples that measures the inhibition of dehydrogenase activity of the bacterium Arthrobacter globiformis using the redox dye resazurin. The miniaturized aerobic suspension assay provides a screening result within 6 hours, enabling fast assessment of bioavailable toxicants in soils and waste materials. The document updates and supersedes EN ISO 18187:2018 and was prepared by ISO/TC 190 in collaboration with CEN/TC 444.
Key topics and technical requirements
- Test principle: Determine inhibition of A. globiformis dehydrogenase activity caused by water‑soluble or solid‑bound non‑volatile contaminants; measured via resazurin reduction (fluorescence).
- Scope of applicability: Natural samples such as soils and various waste materials; also allows testing of chemical substances (Annex C).
- Test format: Miniaturized solid contact assay in an aerobic suspension - designed to be rapid, cost‑effective and sensitive.
- Quality controls and validity:
- Use of reference substances and positive controls; updated validity criteria include alternative positive controls (e.g., copper sulfate, 3,5‑dichlorophenol, zinc sulfate) spiked into quartz sand for waste testing.
- Procedures for calculating relative fluorescence and percentage inhibition to express results.
- Methods and procedures covered: Reagents and materials, test organism preparation (Annex B), apparatus, incubation and fluorescence measurement, calculation, statistical analysis and reporting.
- Interferences and mitigation: Guidance on factors affecting assay performance (e.g., plastics, low‑density waste) and methodological alternatives to reduce uncertainty.
- Organism identification: Genome sequencing is recommended for confirming A. globiformis identity (updated from microbiological strips).
Applications and practical value
- Rapid biological screening for potentially contaminated soils and waste prior to detailed chemical analysis.
- Triage tool in contaminated land assessment, site investigation, landfill and waste characterization, and environmental monitoring.
- Useful in research settings for ecotoxicological studies exploring bioavailability and microbial enzyme inhibition.
- Supports environmental decision making by providing a biologically relevant indicator of toxicity that complements physical and chemical data.
Who should use this standard
- Environmental testing laboratories and contract labs
- Soil scientists, ecotoxicologists and remediation consultants
- Waste management professionals and landfill operators
- Regulatory agencies and compliance officers conducting screening-level assessments
Related information
- Supersedes EN ISO 18187:2018; prepared by ISO/TC 190 (Soil quality) with CEN/TC 444. Key annexes: Annex A (interlaboratory results), Annex B (test organism preparation), Annex C (chemical testing).
