Overview
EN ISO 10298:2020 (identical to ISO 10298:2018) provides a standardized source of acute inhalation toxicity data for gases and gas mixtures to support the safe selection of cylinder valve outlets. The document lists best-available LC50 (lethal concentration for 50% of test animals) values-referenced to a 1 h exposure-and gives rules for deriving mixture toxicity and for selecting appropriate toxicity classifications used in cylinder outlet selection and related safety/regulatory tasks.
Key topics and requirements
- Scope and purpose: Compile reliable acute-toxicity data from literature to classify gases and gas mixtures for inhalation toxicity.
- Toxicity metrics: Defines key terms such as LC50, LCLO, LD50 and toxicity levels (Subdivision 1–3) used for cylinder valve selection and transport classification.
- Exposure basis: LC50 values in Annex B correspond to 1 hour exposure (typically in albino rats). Conversion guidance for other exposure times is provided (Annex A).
- Time adjustment principles: Explains use of Haber's rule and a square‑root time adjustment approach when converting between exposure durations; notes the conversion convention used when relating ISO values to GHS 4‑hour categories.
- Mixture calculation: Specifies a calculation method to estimate a gas-mixture LC50 from component LC50s and component mole fractions (Formula in Clause 4.3). Synergistic effects are not accounted for in the formula.
- Data quality and test methods: Recommends use of internationally recognized test methods (e.g., OECD TG 403) for new toxicity data and discusses animal‑welfare considerations-use calculation when component data are available.
- Annexes:
- Annex A - guidance on selecting LC values and time extrapolation,
- Annex B - tabulated LC50 values for toxic gases and vapours.
Applications and users
EN ISO 10298:2020 is used by:
- Cylinder and valve manufacturers to determine compatible valve outlet types according to toxicity classifications.
- Industrial gas suppliers for classification and labelling of gas cylinders.
- Safety engineers, EHS professionals and risk assessors evaluating inhalation hazards.
- Regulatory and transport authorities referencing toxicity data for classification (including alignment with GHS categories).
- Standards committees and laboratories generating or validating inhalation toxicity data.
Related standards
- ISO 5145 - valve outlet dimensions for gas cylinders.
- ISO 14456 - criteria for compatible gas groups.
- GHS (Globally Harmonized System) - classification guidance for inhalation toxicity (4 h basis).
- OECD TG 403 - inhalation toxicity test method.
Keywords: EN ISO 10298:2020, ISO 10298:2018, gas cylinders, toxicity, LC50, cylinder valve outlets, gas mixtures, inhalation toxicity, GHS, ISO 5145.
