Ethics of Research involving animals
Animal use in toxicity studies
Introduction
9.1 In this chapter we describe the purpose and principal methods of toxicity studies. Most of these studies are conducted to assess the degree to which substances are toxic (poisonous) for humans, animals or the environment, to investigate the mechanism of toxic chemicals, or to develop new or improved tests for specific types of chemically induced effects. We begin by explaining the scientific rationale behind important types of studies. These include: examination of adverse effects that may occur on first exposure to a single dose of a substance (acute toxicity studies), studies that seek to assess the potential of substances to interact with genetic material (genotoxicity), tests that aim to identify whether toxicity occurs after continuous exposure to a substance (repeated-dose toxicity studies), tests that are undertaken to find out whether cancers may develop as a result of exposure to certain chemicals, and studies to ensure the safety of medicines.
9.2 In the second part of the chapter we discuss a range of welfare implications that may arise for animals involved in toxicity testing. We consider first effects that may result from the dosing and sampling methods that are commonly used, and then effects related directly to the toxicity of the chemical that has been administered. Toxicity studies are highly variable in design, and where they involve the use of animals the implications for animal welfare must be considered on a case by case basis. We concentrate here on the more standardised animal methods that are widely used to characterise the adverse effects of chemicals on human and animal health, and on the environment. Many of the tests described are also used in the testing of medicines. For the most part we do not differentiate in the description between these different purposes.
| Box 9.1: Toxicity studies – number of animals used Procedures for toxicological purposes accounted for 16 percent of all animal procedures undertaken in 2003 in Great Britain. Approximately ten percent of all animal procedures were carried out for pharmacological safety and efficacy studies. About 13 percent of all animal procedures were toxicological tests conducted to conform to legislative or regulatory requirements. Source: Home Office (2004) Statistics of Scientific Procedures on Living Animals Great Britain 2003 (London: HMSO). |
Footnotes
1 European Commission (2004) Opinion of the Scientific Committee on Toxicity, Ecotoxicity and the Environment on The BUAVEuropean
Coalition to End Animal Experiments Report: The Way Forward - Action to End Animal Toxicity Testing, available at:
http://europa.eu.int/comm/health/ph_risk/committees/sct/documents/out217_en.pdf. Accessed: 26 Apr 2005.
2 The information that must be supplied by a manufacturer is laid down in the Dangerous Substances Directive (67/548/EEC),
implemented in the UK by the Notification of New Substances Regulations 1993.