Overview
ISO 8259:2024, "Soil quality - Bioaccessibility of organic and inorganic pollutants from contaminated soil and soil-like materials," provides a standardized method for testing the bioaccessibility of substances from contaminated soil and soil-like materials. Developed by the International Organization for Standardization (ISO), this standard is critical for laboratories, environmental professionals, and regulatory bodies involved in soil risk assessment and contaminated land management. The method aims to estimate the fraction of pollutants that could potentially become available for absorption in the human gastrointestinal tract following ingestion, thereby supporting more accurate human health risk assessments. Notably, this method is not applicable for volatile contaminants and requires suitable analytical methods for extraction and detection of a broad range of substances.
Key Topics
- Bioaccessibility Testing: Focuses on the estimation of the fraction of pollutants (such as metals, PAHs, PCBs) becoming available for absorption after ingestion. The method simulates human digestion using artificial gastric and intestinal juices.
- Scope and Limitations: Applicable to non-volatile organic and inorganic contaminants, provided suitable detection methods are available. Volatile substances like certain PAHs (naphthalene, acenaphthene, etc.) are excluded due to their loss during testing.
- Sample Preparation: Emphasizes the importance of using the ≤2 mm particle size fraction to simulate ingestion by children and for practical laboratory handling. Duplication testing and quality assurance requirements are specified.
- Test Procedure: The test mimics realistic physiological conditions (temperature, agitation, pH) using artificial digestive juices and food surrogates (such as milk powder) to accurately reflect human gastrointestinal processes.
- Quality Assurance: Mass balance and recovery calculations are required, alongside appropriate sample handling and retention practices for reliable, repeatable results.
- Applicability: Suitable for both anthropogenically and geogenically contaminated soils, as well as various soil-like materials such as ash, dust, sediments, and waste materials.
Applications
- Human Health Risk Assessment: The primary application is to inform detailed, site-specific risk assessments by providing a realistic estimate of the bioaccessible fraction of soil contaminants relevant to oral ingestion, especially in children.
- Environmental Site Investigation: Supports regulatory compliance and remediation planning by identifying sites where total contaminant measures may overestimate actual exposure risk.
- Research and Development: Useful for academic, governmental, and private sector research into soil contamination, contaminant behavior, and human exposure pathways.
- Policy and Regulation: Assists policymakers and regulators in establishing safety standards and clean-up thresholds based on bioaccessibility rather than total contaminant concentrations, thus potentially reducing unnecessary remediation.
- Interlaboratory Comparison: Standardizes methods and reporting, ensuring consistency and comparability between laboratories and across studies.
Related Standards
- ISO 15800: Provides guidance on soil and site characterization for evaluating human exposure to substances present in soil, including bioaccessibility and bioavailability.
- ISO 17402: Outlines the concept of bioavailability, definitions, and assessment methods for various exposure pathways in contaminated soils.
- ISO 17924: Describes a method specifically for assessing the bioaccessible fraction of metals in contaminated soil following ingestion and distinguishes between separate gastric and combined gastric-intestinal phases.
Keywords: ISO 8259, soil quality, bioaccessibility, contaminated soil, organic pollutants, inorganic pollutants, human health risk assessment, in vitro digestion, artificial digestive juices, environmental standard, soil contamination testing, risk management, laboratory methods, soil remediation, PAHs, PCBs, heavy metals.
By adhering to ISO 8259:2024, stakeholders ensure rigorous, harmonized assessment of pollutant bioaccessibility in soils, leading to improved public health protection and evidence-based environmental decision-making.