Ethics: Using Animals to Test for Toxic Properties in Pharmaceuticals and Other Chemicals
This is an area on which much has been said and written over a very long time. This short piece simply aims to set out the context of the main aim of the ESNATS programme. This aim is to reduce significantly the numbers of animals currently used for toxicology testing during drug development by replacing parts of the required animal tests using human embryonic stem cells or somatic cells derived from them.
Animals are used to try to estimate beforehand if a compound that is proposed for human use is likely to prove toxic. This has been criticised by many people, especially groups opposed to animal testing, on many grounds. Some object in principle to what is seen as the violation of the intrinsic value of fellow creatures, others object to inflicting serious harm on other sentient beings, and that experiments on animal species have, at best, only a limited ability to predict the behaviour of the chemical concerned on humans, because of inter-species differences. This latter point is well taken by many who work in the field of toxicology. But one argument generally given in response is that limited data are better than none, if the aim is to avoid serious toxic effects in humans.
For many years there has been an increasing emphasis on three principles applied to animal experimentation in general, known as "the 3Rs", namely Reduce, Refine and Replace. Reduce the number of animals used, refine the methods in relation to the welfare of the animal, and look to replace the use of animals wherever possible. These principles are widely recognised in both academic research and also industry. As well as ethical and humane concerns, animal experiments can also be very expensive. The best initiatives are coming from collaboration between the different sectors and stakeholders.
Despite the general acceptance in theory, the practice of finding replacements, reducing numbers and refining procedures is patchy. Animal welfare organisations are constantly pressing for greater urgency, wider uptake, better co-ordination, and regulatory changes. In some areas, real strides have been made; in others, rather little has changed. Overall, the downward trend is somewhat offset by the emergence of new areas of scientific activity which have created new demands for animal experiments, such as in human genetics, stem cells and nanotechnology, and the potentially very large increase in testing arising out of the need to establish the safety of some 30,000 existing chemicals under the EC REACH Directive.
ESNATS seeks to address one notable area of animal experimentation, that of using animals for a range of testing procedures for the toxic effects of pharmaceuticals and other chemicals on especially on human reproduction and development (reproductive toxicology), the human nervous system (neuro-toxicology). By using human cells, the programme aims to achieve two ethical advantages.
One is to do the basic research on stem cell production and differentiation, and applied research on validation and quality control, which will enable tests to be developed which will replace a significant number of animal trials.
The second is to lead to a better quality type of toxicological data, by relying on the response of human cells rather than animals.
Set against this ethically, however, is the need to use of human embryos to derive the human cells. This poses a serious ethical dilemma which we discuss further in < Can Human Embryonic Stem Cells be an Ethical Alternative to Animal Experiments?>