| IMPORTANT NOTE: This document is reproduced for reference purposes only, it contains false and unsubstantiated claims designed to mislead the public. It MUST be viewed in conjunction with its rebuttal (which can be viewed by selecting this link). |
forms. These tests have greatly reduced the number of animals used in LD50 testing.
In fact, the days of the LD50 test may be numbered. A new test, the Acute Toxicity Limit Dose test (LDT), has been developed. It promises to further reduce the numbers of animals used in safety testing.
In the long term, there are hopes that computer simulation will reduce the need for animal testing even further. Already there are programmes which can predict toxicity, but these are only experimental.
New substances are tested on animals to see whether they cause cancer. Tests involve life-time feeding trials, using strains of laboratory animals which are known to be susceptible to cancer.
If low doses of a substance cause cancer, these tests work very well. However, there is a lot of debate in scientific circles about the value of testing substances which only cause cancer at very high doses.
Critics ask whether feeding high levels of a relatively safe chemical over a long period has much relevance to chemical exposure in everyday life. They say that any cancer which arises in these trials may be more a result of stress on the test animals than the cancer-causing ability of the product being tested.
On the other side of the debate there are some doctors and medical scientists who argue that there is no particular dose at which a cancer-causing chemical can be said to be safe.
In modern western societies, many of us want ever-tighter assurances that we aren't being exposed to environmental cancer risks, such as ultraviolet rays.