Andrew Rowan has written an update on animal use in drug company research, and of course, it touches on numbers of animals, and trends in numbers used. Andrew has been following this issue for a long time, and it’s his book, Of Mice, Models and Men that made me realize that any description of lab animal use for non-lab animal users had to include some description of the kinds of animals used and the numbers used. Many things have changed since his 1984 book that can affect numbers of animals used, in different directions. It does seem (but as I say, in the US, No One Knows) that animal use in commercial safety and toxicity is decreasing. Credit Henry Spira in the late 70s for bringing rabbit eye irritancy testing of cosmetics to public attention. Replacement of animals in safety testing, and changes in regulations for safety testing, may indeed be reducing animal use in this field (Joanne Zurlo et al wrote a good overview of this, though it needs an update). In the other direction. Right around that time, scientists Mintz and Jaenisch “created” the first transgenic mouse, and technologies for genetically engineering laboratory animals have been causing a boom in mouse and zebra fish use for decades now (as far as I can tell: No One Knows as no one counts these animals in the US in a systematic way).
So, animal use in the US is decreasing in some areas and increasing in others, as far as we know. And so, how many animals are used in US labs? Like myself and others, Andrew Rowan is trying to estimate what we can only see indirectly, with each of us looking into a dark room via a different keyhole (are there still keyholes? Need a better metaphor on that). He has been closely following Great Britain stats over a few decades (where there is a legal requirement for transparency and reporting) older US literature such as survey from the National Academies’ division (ILAR) that covers animal research. His approach makes an effort to incorporate differences in use in academia versus in industry, though he has not recently published an attempt at estimating total US animal use.
He reminded me of a 1987 report on lab animal use sponsored by the US Office of Technology Assessment (OTA). That report also tried looking through a few keyholes to estimate US animal use at the time, with this caveat:
“There are no easily obtainable data in the United States allowing an accurate estimate of animal use for research, testing, and education that satisfies all interested parties; estimates range over a full order of magnitude, from approximately 10 million to 100 million animals. These estimates have all been prepared by different people or institutions with different data sources under different standards (e.g., different time periods or definitions). Comparison of the various estimates is difficult and, in many cases, impossible.”
BOTTOM LINE on this question at this point: we really do not know how many mice are used in US labs (and know even less how many zebra fish). I know my own estimate may be high or low, if patterns of use are significantly different in pharma versus academia are significantly different. It may well under-report mouse use at the institutions I surveyed if they base their annual estimate of mouse use on their daily inventory of occupied cages.