es test uses salmonella bacteria to detect any carcinogenicity (the ability to cause or promote cancer) (8). This test has been validated and accepted for screening purposes in toxicology. The LAL test for endotoxins has also been validated for certain purposes. This test detects the presence of fever-inducing endotoxins in intravenous products. This is made possible from blood samples gathered in the wild from horseshoe crabs. The researcher extracts amoebocyte lysate from the samples and mixes it with the endotoxin to see if a reaction occurs (8). Also, hydra can be used to screen for teratogenicity, which is the production of malformations in the embryo. Yeast cells and tobacco plant pollen tubes have also been suggested for toxicity testing. Advances in genetic engineering are opening up even more possibilities to replace the use of higher animals. Genetically engineered roundworms, because they carry human disease genes, have already been used to identify new drugs. Many studies on the development and growth can be carried on animal embryos in vitro rather than in the pregnant mother. Rodents are usually used in these procedures. Fertilized chicken eggs are also used in a test called the HETCAM, which predicts eye irritancy. The researcher can observe the effects a chemical has on the chorioallantoic membrane of the egg (5).If sufficient consideration is given to ethical and safety issues, studies on humans can replace the use of animals in some cases. Clinical studies in humans have always been required to register drugs, and human volunteers are being used more and more for the skin testing of cosmetics. Non-invasive methods can be used in healthy subjects to investigate disease processes. Some of these methods are nuclear magnetic resonance, electron spin resonance, and positron emission tomography. The great advantage to human studies is that they deal with human beings in their normal environments.Finally, the...
