Phototoxicity Testing

Phototoxicity testing identifies and evaluates the potential of chemical agents to induce toxicity upon subsequent exposure to light.

Understanding Phototoxicity Testing

Phototoxicity is defined as a toxic response that is induced upon initial exposure of skin to a test chemical or systemic administration, and subsequent exposure to light. The in vitro 3T3 BRU Phototoxicity test is a very sensitive assay that evaluates the potential of a chemical agent to induce phototoxicity.

Evaluation of potential of a chemical agent to elicit or increase a toxic response upon dermal or systemic exposure followed by exposure to a nontoxic dose of UVA and visible light is an important component of toxicological testing of pharmaceuticals and cosmetics.

Any compound that absorbs light within the range of natural sunlight (290-700nm) and generates reactive species following absorption of UV-visible light and is distributed sufficiently to light-exposed tissues poses phototoxicity concern and should be investigated.

Toxikon offers GLP and non GLP phototoxicity tests using highly sensitive in vitro 3T3 neutral red uptake method per OECD 432 guidelines using Honle SOL 500 lamp.

The test article will be dissolved in suitable solvent and tested at 8 concentrations to evaluate concentration response and calculate mean photo effect (MPE).

Phototoxicity Testing Capabilities

Toxikon has over 4 decades of experience performing cytotoxicity assays and offers the following related services.

  • In Vitro NRU cytotoxicity Assay
  • MEM Elution cytotoxicity assay
  • MTT cytotoxicity assay


  • OECD 432 In Vitro 3T3 NR U phototoxicity test
  • ISO 10993-5, 2009, Biological Evaluation of Medical Devices – Part 5: Tests for In Vitro Cytotoxicity.
  • United States Pharmacopeia 40, National Formulary 35, 2017. <87> Biological Reactivity Tests, In Vitro.

Testing Categories and Specifications

  • In Vitro 3T3 NR U phototoxicity test