Question to the Home Office:

To ask the Secretary of State for the Home Department, with reference to her Department’s publication entitled Annual statistics of scientific procedures on living animals, Great Britain 2024, published on 23 October 2025, what assessment she has made of the potential implications for her policies of the increase in the number of procedures conducted for LD50 and LC50 tests from 2023 to 2024.

The Lethal Dose 50 and Lethal Concentration 50 procedures are subject to strict regulations under the Animals (Scientific Procedures) Act 1986. This legal framework requires that animals are only ever used in science where there are no alternatives, where the number of animals used is the minimum needed to achieve the scientific benefit, and where the potential harm to animals is limited to that needed to achieve the scientific benefit.

Some authorised medicines in the UK include quality control tests which require the use of animals, conducted to ensure the quality, safety, and efficacy of specific medicines. These tests account for the LD50 cases still conducted.

The requirement for LD50 and LC50 tests is set by the Organisation for Economic Co-operation and Development (OECD) guidelines and the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) regulations set by the Department for Environment, Food & Rural Affairs.

This Government is committed to the development of non-animal alternatives and will publish a strategy by the end of this year to support the development, validation and uptake of alternatives to animal testing.