Question to the Home Office:

To ask the Secretary of State for the Home Department, how many animals were used in LD50 tests to evidence compliance with UK-only regulations in each of the last five years.

The Home Office publishes detailed annual statistics on the use of animals in science, including procedures for acute and subacute toxicity testing which covers tests such as LD50 (Lethal Dose 50) and LC50 (Lethal Concentration 50). These figures represent the total number of procedures carried out in this category each year.

The Home Office does not collect information on whether individual procedures were conducted specifically to meet UK only regulatory requirements, so the data is not available in the form requested.

Based on the published annual statistics, the total number of procedures in the acute and sub‑acute toxicity category (which includes LD50 and LC50 tests) in each of the last five years is as follows:

2024: 11,992

2023: 11,519

2022: 12,651

2021: 11,758

Statistics for 2025 have not yet been published. Official statistics on the use of animals in science are released annually and are available here:
www.gov.uk/government/collections/animals-in-science-statistics