ISO 16638-2:2019

Overview

ISO 16638-2:2019 - Radiological protection: Monitoring and internal dosimetry for specific materials - Part 2: Ingestion of uranium compounds - provides minimum requirements and principles for designing professional monitoring programmes and internal dosimetry specifically for occupational ingestion of uranium and its compounds. The standard focuses on harmonizing monitoring goals, dose‑assessment procedures and interpretation of bioassay data to achieve reliable outcomes for both radiological and chemical toxicity concerns. It complements related standards on inhalation (ISO 16638‑1) and on laboratory and dose assessment practices.

Key technical topics and requirements

• Scope and purpose: Defines when monitoring for ingestion is required and the objectives of confirmatory, task‑related and special monitoring programmes.
• Monitoring programme design: Information needed to design programmes (work practices, potential exposures, protective measures) and criteria for selecting suitable monitoring methods.
• Individual monitoring and bioassay: Guidance on in vitro analyses (urine, faeces, nasal samples) and interpretation of bioassay results for intake estimation and committed effective dose (integration period defined as 50 years).
• Dose assessment procedures: Standardized procedures and assumptions for converting monitoring data into intake and dose estimates, and limits indicating when more sophisticated methods are necessary.
• Performance criteria and laboratory reference values: Reference values and performance indicators for bioassay laboratories to ensure reliable results.
• Uncertainty and decision criteria: Treatment of uncertainties in dose assessment, decision thresholds, detection limits and criteria for determining the significance of monitoring results.
• Quality assurance, reporting and records: Requirements for QA/QC of laboratories and the dose assessment process, documentation, reporting formats and record keeping.
• Informative annexes: Supporting material includes nuclear data for U‑238 and U‑235, classification of uranium compounds, measurement techniques for ingestion cases, excretion rates, committed effective dose per unit intake and guidance on uncertainty estimation.

Note: ISO 16638‑2 does not provide detailed measurement techniques, inhalation dosimetry, modelling improvements, counter‑measure effects (e.g., chelation) or root‑cause investigations.

Practical applications and target users

Who uses ISO 16638‑2:

• Radiation protection officers and health physicists designing workplace monitoring programmes for uranium facilities.
• Employers in nuclear, mining, processing and research sectors handling uranium compounds.
• Occupational hygienists and industrial safety teams assessing ingestion risks and work practices.
• Bioassay laboratories seeking performance criteria and QA guidance for uranium analyses.
• Regulatory authorities and accreditation bodies harmonizing monitoring and dose assessment requirements.

Typical applications:

• Designing confirmatory or special monitoring after suspected ingestion events.
• Setting sampling schedules and bioassay types (urine/faeces) for task‑related monitoring.
• Converting bioassay results into committed effective dose estimates and reporting compliant documentation.

Related standards

• ISO 16638‑1 (inhalation of uranium compounds)
• ISO 20553 (monitoring programmes)
• ISO 28218 (laboratory requirements for bioassay)
• ISO 27048 (dose assessment software and methods)

Keywords: ISO 16638-2, radiological protection, internal dosimetry, uranium ingestion monitoring, bioassay, occupational exposure, monitoring programme, dose assessment, quality assurance.