ISO 4962:2024

Overview

ISO 4962:2024 is an international standard from ISO focused on nanotechnologies, specifically providing a validated in vitro procedure for assessing acute nanoparticle phototoxicity. The standard outlines a method to evaluate the potential phototoxic effects of nanoparticles (NPs) suspended in cell culture media by measuring the reduction in cellular viability after exposure to near ultraviolet A (UVA) light (315 nm to 400 nm). By comparing the in vitro photoactivity of nanoparticles to a known positive control (chlorpromazine), this standard helps determine the acute phototoxicity of various nanomaterials, including nanoparticle aggregates and agglomerates. The standard is not intended for predicting other light-material interaction effects like genotoxicity, photo-allergy, or photo-mutagenicity.

Key Topics

• Phototoxicity Evaluation: The core of ISO 4962:2024 is the procedure to measure acute phototoxicity of nanoparticles. Phototoxicity refers to toxic responses triggered or intensified upon exposure to light, particularly UVA, due to activation of photoreactive substances.
• Test Methodology: The standard specifies using a 96-well plate format, incorporating a controlled UVA light source, and optical plate readers for rapid and reproducible results. Cell viability is determined after NP/UVA exposure by standard colorimetric assays.
• Controls and Comparisons: Simultaneous use of positive (chlorpromazine) and negative (cell media) controls is required to benchmark any phototoxic effects observed.
• Sample Preparation and Validation: Detailed steps on how to prepare, dose, and characterize nanoparticle suspensions are provided, with special attention to avoiding endotoxin contamination and verifying NP dispersion and stability in the test medium.
• Assay Interference: The standard addresses potential artefacts and interference from nanoparticles with the cell viability assay, ensuring that measured cell toxicity is truly due to phototoxic mechanisms.

Applications

ISO 4962:2024 is a valuable tool for researchers, regulatory agencies, material scientists, and industries engaged in the development and safety assessment of nanoparticles. Typical applications include:

• Safety Testing of Nanomaterials: Evaluate potential acute phototoxic risks during the development of nanotechnology-enabled products such as cosmetics, sunscreens, topical medications, advanced coatings, and medical devices.
• Product Development: Guide manufacturers in screening the phototoxic behavior of nanoparticle formulations early in the design process to ensure consumer and environmental safety.
• Regulatory Submissions: Provide evidence of compliance with international best practices for nanomaterial safety, increasingly required for regulatory approvals in biotechnology, healthcare, and consumer goods.
• Comparative Material Studies: Enable consistent comparison of phototoxic potential between different NP types (e.g., TiO₂, ZnO, quantum dots, metal nanoparticles) or between nano-formulated and traditional products.
• Academic Research: Facilitate fundamental research into biological effects of nanomaterials, supporting reproducibility and cross-laboratory consistency in toxicity testing.

Related Standards

To ensure comprehensive evaluation and reporting in nanoparticle toxicity and characterization, the following related standards are often referenced alongside ISO 4962:2024:

• ISO 80004-1:2023 - Nanotechnologies - Vocabulary - Part 1: Core vocabulary (provides definitions for key nanotechnology terms)
• ISO 22412 - Particle size analysis - Dynamic light scattering (DLS) (used for verifying NP dispersion)
• ISO 29701 - Nanotechnologies - Endotoxin test on nanomaterial samples for in vitro systems (addresses endotoxin contamination detection)
• ISO 19007 - Nanotechnologies - In vitro MTS assay for measuring cell viability (referenced for cell viability assessment procedure)
• OECD 432 - In vitro 3T3 NRU phototoxicity test (relevant for soluble chemicals; background for method differentiation)

By following ISO 4962:2024, stakeholders can apply a harmonized, robust approach to nanoparticle phototoxicity screening, supporting safe innovation in nanotechnology and alignment with international regulatory expectations.