Top 10 Deadliest Animals On The Planet

Toxicology testing, also known as safety testing, is conducted by pharmaceutical companies testing drugs, or by contract animal testing facilities, such as Huntingdon Life Sciences, on behalf of a wide variety of customers.[173] According to 2005 EU figures, around one million animals are used every year in Europe in toxicology tests; which are about 10% of all procedures.[174] According to Nature, 5,000 animals are used for each chemical being tested, with 12,000 needed to test pesticides.[175] The tests are conducted without anesthesia, because interactions between drugs can affect how animals detoxify chemicals, and may interfere with the results.[176][177] A rabbit during a Draize test.

Toxicology tests are used to examine finished products such as pesticides, medications, food additives, packing materials, and air freshener, or their chemical ingredients. Most tests involve testing ingredients rather than finished products, but according to BUAV, manufacturers believe these tests overestimate the toxic effects of substances; they therefore repeat the tests using their finished products to obtain a less toxic label.[173]

The substances are applied to the skin or dripped into the eyes; injected intravenously, intramuscularly, or subcutaneously; inhaled either by placing a mask over the animals and restraining them, or by placing them in an inhalation chamber; or administered orally, through a tube into the stomach, or simply in the animal’s food. Doses may be given once, repeated regularly for many months, or for the lifespan of the animal.[citation needed] 

There are several different types of acute toxicity tests. The LD50 (“Lethal Dose 50%”) test is used to evaluate the toxicity of a substance by determining the dose required to kill 50% of the test animal population. This test was removed from OECD international guidelines in 2002, replaced by methods such as the fixed dose procedure, which use fewer animals and cause less suffering.[178][179] Abbott writes that, as of 2005, “the LD50 acute toxicity test … still accounts for one-third of all animal [toxicity] tests worldwide.”[175] 

Irritancy can be measured using the Draize test, where a test substance is applied to an animal’s eyes or skin, usually an albino rabbit. For Draize eye testing, the test involves observing the effects of the substance at intervals and grading any damage or irritation, but the test should be halted and the animal killed if it shows “continuing signs of severe pain or distress”.[180] The Humane Society of the United States writes that the procedure can cause redness, ulceration, hemorrhaging, cloudiness, or even blindness.[181] This test has also been criticized by scientists for being cruel and inaccurate, subjective, over-sensitive, and failing to reflect human exposures in the real world.[182] Although no accepted in vitro alternatives exist, a modified form of the Draize test called the low volume eye test may reduce suffering and provide more realistic results and this was adopted as the new standard in September 2009.[183][184] However, the Draize test will still be used for substances that are not severe irritants.[184] 

The most stringent tests are reserved for drugs and foodstuffs. For these, a number of tests are performed, lasting less than a month (acute), one to three months (subchronic), and more than three months (chronic) to test general toxicity (damage to organs), eye and skin irritancy, mutagenicity, carcinogenicity, teratogenicity, and reproductive problems. The cost of the full complement of tests is several million dollars per substance and it may take three or four years to complete. 

These toxicity tests provide, in the words of a 2006 United States National Academy of Sciences report, “critical information for assessing hazard and risk potential”.[185] Animal tests may overestimate risk, with false positive results being a particular problem,[175][186] but false positives appear not to be prohibitively common.[187] Variability in results arises from using the effects of high doses of chemicals in small numbers of laboratory animals to try to predict the effects of low doses in large numbers of humans.[188] Although relationships do exist, opinion is divided on how to use data on one species to predict the exact level of risk in another.[189]