Non-human primates in research and safety testing

1. Introduction – Overview of the use of primates in research and testing in the EU

Use of primates in EU research and safety testing

Experiments on non-human primates (NHPs) have brought about important advances in biology and medicine. Primates often play a crucial role in the safety testing of new drugs and in research aimed at understanding how the brain works and how to prevent infectious diseases in humans.

Worldwide, more than 100 000 primates are used each year for biomedical animal experimentation: over half in the USA, one tenth in Europe and the rest in Japan and other countries. Primates represent a tiny proportion of the total number of animals used in experiments (less than 1 out of thousand animals in the EU and approximately 3 out of thousand in the US). According to the pharmaceutical industry, of all the primates used, less than 0.1% are involved in experiments where their level of suffering is categorised as “substantial”.

Non-human primates are a group of mammals composed of simians – monkeys and apes – and prosimians, such as lemurs. Monkeys are further divided into two subgroups: Old World monkeys, which are native of Africa and Asia, and New World monkeys, which originate from Central and South America.

The most frequently used primate species are the long-tailed macaque and the rhesus monkey (both Old World monkeys). In Europe, there is a shift towards using more new-world primates and fewer prosimians. Great Apes were not used in the EU in 2005.

In the EU, animal experimentation is regulated and is only allowed in specific research areas.

Safety testing of new drugs, substances and devices, especially those aimed for human medicine and dentistry, accounts for about 67% of the total number of NHPs used. Almost all these tests on primates are mandatory and requested by safety testing regulations. Of all primates used in safety testing, approximately half are involved in mid- to long-term toxicity studies, which entail repeated administration of the substance; one third are involved in single-administration studies; and the rest are used to study the effects on reproduction and development or for other tests.

Primates are also used in fundamental biological research (about 14% of all NHPs used) as well as in research and development of medical and dental products and devices for humans (about 13% of all NHPs used).

Nearly all primates used in scientific experiments are born to animals that are themselves bred in captivity, sometimes for several generations. Wild-caught animals are very rarely used but are nonetheless still needed to avoid the adverse effects of inbreeding of stocks. Captive-bred animals give more accurate, reliable and reproducible data. However, research on aging and on pregnancy is more reliable if conducted on wild-caught animals.

One way to avoid inbreeding while reducing the use of wild primates is to exchange wild-caught males between facilities, as zoos do. Another option is to use the captive offspring of wild-caught parents for breeding only and not for research. However, this would create a shortage of animals for experimentation that, in the short term, would result in more wild primates being captured to increase the breeding stock. Another complication relates to the difficulty to breed successive generations from captive-born parents because such animals often show reduced birth rates and poor mothering, and their offspring can have health problems.

It is important to note that in recent years there have been major investments to improve housing conditions for primates. More...