Overview
ISO 22190:2020 - Soil quality - Use of extracts for the assessment of bioavailability of trace elements in soils - provides guidance on using chemical extraction methods to estimate the bioavailability of trace elements in soils and soil-like materials. The standard explains how extract-based measurements relate to actual availability (dissolved pore-water concentrations) and potential availability (amount releasable under defined worst‑case conditions). Note: the extraction methods themselves are not prescribed by ISO 22190; the document guides their application, interpretation, calibration and reporting.
Key topics and requirements
- Scope and definitions: Clear terminology for bioavailability, environmental availability, actual vs potential availability, bioaccessibility and toxicological bioavailability, aligned with ISO 11074 and ISO 17402.
- Conceptual framework: How total, potential and actual fractions relate to organism exposure; extraction methods model pore-water concentrations and reactive pools.
- Extraction approach: Guidance on use of neutral extracts (to simulate pore water) and acid extracts (to measure potential availability), and on impacts of ionic strength, pH and dissolved organic carbon (DOC) on extract results.
- Tiered assessment: Use of extract data within a tiered risk-assessment workflow to improve exposure estimates versus relying on total concentrations.
- Procedure, reporting and calibration: Recommendations for general procedures using extracts, standardized reporting elements, and calibration of extract results toward biological targets (transfer functions), including discussion of limits and applicability.
- Limitations: Emphasis that extract-based methods are equilibrium‑based and may not capture kinetically controlled (non‑equilibrium) bioavailability.
Applications and users
ISO 22190 is practical for:
- Environmental consultants and contaminated‑land practitioners performing site risk assessments.
- Soil and environmental laboratories interpreting extract data for trace elements.
- Regulators and policymakers setting guidance or decision frameworks that incorporate bioavailability.
- Researchers developing or calibrating transfer functions linking chemical extracts to biological responses.
Practical uses include refining exposure estimates for ecological and human health risk assessments, prioritizing remediation, and informing monitoring strategies where bioavailable fractions matter more than total concentrations.
Related standards
- ISO 17402 - Selection and application of bioavailability assessment methods
- ISO 21268-1 - Neutral aqueous extraction approaches (actual availability)
- ISO 17586 - Acid extraction approaches (potential availability)
- ISO 17924 - Human bioaccessibility (in vitro gastrointestinal simulation)
- ISO 11074 - Soil quality vocabulary
Keywords: ISO 22190:2020, soil quality, bioavailability, trace elements, soil extracts, neutral extract, potential availability, actual availability, environmental bioavailability, risk assessment.