Knight A, Bailey J, Balcombe J. Animal experiments harm human health. Amer Chronicle 2005, 8 Oct.
www.americanchronicle.com/articles/viewArticle.asp?articleID=2819.


Industrial lobbyist Frankie Trull has once again trotted out her tired old claim that animal experiments are essential for the advancement of medical progress (American Chronicle Oct. 5, 2005, [www.americanchronicle.com/articles/viewArticle.asp?articleID=2756]). With millions of dollars annually spent on such experiments unavailable for potentially lifesaving initiatives such as epidemiological research or health and nutrition education, the true value of animal experiments warrants closer scrutiny.

Earlier this year we critically examined the value of animal experiments in safeguarding human health. Cancer is the second leading cause of death in developed societies, and many millions of dollars, animal lives, and skilled personnel hours are spent annually on animal tests for human carcinogenicity. However, our surveys of major toxic chemical databases used by government regulatory authorities show that animal experiments yield useful human risk assessments for substantially less than half the chemicals tested. We found that over-reliance on animal data has commonly undermined predictions of the human risk of chemicals, with major implications for public health [i-ii].

Similarly, maternal exposures to teratogens during pregnancy cause thousands of human birth defects annually. The medical costs are in the millions; the human costs are incalculable. Despite similar investments to those of cancer research, our survey of animal test results demonstrated widespread discordance among all species used. For known human teratogens, mean positive predictivity barely exceeded 50% [iii]. Even sidestepping the ethical considerations of such profligate animal use, reliance on animal test data for human public health decisions constitutes bad science at best, and at worst risks human lives.

But ethical considerations relating to experimental animal use must not be sidestepped. Millions of animals die every year in toxicity tests such as these, which are rated among the most painful and stressful of procedures. Nor is their suffering brief. Dosing in the standard rodent test begins at six to eight weeks of age and continues for two years, after which any remaining survivors are killed and autopsied.

Even routine procedures such as handling, blood collection, and gavaging (insertion of a stomach tube for the delivery of test chemicals or drugs in toxicity tests) cause significant fear and stress, that also affect experimental results. Our review of eighty published studies on rats, mice, monkeys, dogs, rabbits, hamsters, bats, or birds showed rapid, profound elevations in stress-related responses such such as blood hormone levels and heart rate, for each of these procedures [iv].

When not subject to human manipulation, laboratory animals spend most of their lives confined in small, barren cages, often in social isolation. Our review of one hundred and ten scientific studies found growing evidence that these conditions take a severe toll on the animals’ neurological and psychological health. Even so-called ‘enriched’ environments fail to ameliorate most of these deficits [v]. Behavioral stereotypies—repetitive, unvarying and apparently functionless behavior patterns that are believed to reflect animal suffering—are common, occurring, for instance, in some 50% of all laboratory housed mice [vi].

Finally, we examined alternative testing protocols, and found that data of superior human predictivity can be produced far more quickly and cheaply by expert computerized analyses of chemical structure, modernised cell culture tests, high-volume DNA tests for detecting genetic damage, expanded human clinical trials, and mandatory reporting of adverse reactions to pharmaceuticals. If we are to consider ourselves an ethical, compassionate and intelligent society, our considerable scientific and medical resources should be directed at the best methods for alleviating both human and animal suffering. Animal experiments are unlikely to either cure human diseases nor eliminate ethical concerns. Instead, government and industry should redirect the enormous funds spent annually on animal experiments into the development and implementation of scientifically-based non-animal alternatives.


Veterinarian Andrew Knight, BSc., BVMS, Cert AW, MRCVS, is the Director of Animal Consultants International (www.AnimalConsultants.org), which provides expert advice on animal policy issues. Medical Scientist Jarrod Bailey PhD is a Senior Research Associate at the School of Surgical & Reproductive Sciences, the University of Newcastle upon Tyne. Biologist Jonathan Balcombe PhD is the author of The Use of Animals in Higher Education: Problems, Alternatives, and Recommendations, and of Pleasurable Kingdom: The Animal Nature of Feeling Good (MacMillan 2006, in press).


[i] Knight A, Bailey J, Balcombe J. Which drugs cause cancer? Animal tests yield misleading results. BMJ USA Oct. 2005 in press.
[ii] Knight A, Bailey J, Balcombe J. Animal carcinogenicity studies: poor human predictivity. Altex: Alternatives to Animal Experimentation 2005;22:24 Special issue. Abstracts 5th World Congress 2005.
[iii] Bailey J, Knight A, Balcombe J. The future of teratology research is in vitro. Biogenic Amines May 2005;19(2):97-146.
[iv] Balcombe J, Barnard N, Sandusky C. Laboratory routines cause animal stress. Contemporary Topics in Laboratory Animal Science Nov. 2004;43(6):42-51.
[v] Balcombe J. 2004. Rodents in impoverished laboratory environments: evidence for psychological trauma. Laboratory Animals 2006. In press.
[vi] Mason GJ, Latham NR (2004) Can’t stop, won’t stop: Is stereotypy a reliable animal welfare indicator? In: Proceedings of the UFAW International Symposium ‘Science in the Service of Animal Welfare’ (Kirkwood JK, Roberts EA, Vickery S, eds). Edinburgh, 2003. Animal Welfare 13, S57-69 (Suppl).