In Vitro Toxicity Testing Is Widely Accepted Method for Determining the Relative Toxicity of Different Chemicals

 

In Vitro Toxicity Testing

In vitro toxicology tests are used to determine the relative toxicity of different chemicals. Relative toxicity is the concentration at which a chemical exerts 50% of its effect on untreated cells. This is also known as the Effective Concentration (EC50) for 50% of a particular chemical. The EC50 is a useful method of comparing the toxicities of different chemicals. In vitro toxicity testing can be used to identify potentially harmful substances and identify drug candidates before they reach the clinic. In vitro test models help to understand chemical-induced toxicity in a more streamlined manner. These tests may complement or replace in vivo methods for the toxicological evaluation of chemicals. In vivo tests are also increasingly used in developing new drugs or pesticides. This means that the in vitro market is set to grow. The market for in vitro toxicity testing is largely driven by the increasing need for non-animal tests.

There are two methods of In Vitro Toxicity Testing: in vitro and in vivo. In vitro tests are conducted outside of a living organism, typically in isolated organs, tissues, or cells. The latter can predict the biological effects of a chemical compound, while in vivo tests involve live organisms. Although in vitro testing can be useful in some cases, it cannot predict how a substance will affect a living organism.

The in vitro toxicity test results cannot accurately predict the toxicity in vivo, however they can provide a valuable insight into the mechanisms of toxicity. However, in vitro testing can be limited to the cellular and molecular level, a fraction of which is in vivo. So in vitro testing does not always predict what will happen in vivo. So, it is always important to use caution when using in vitro methods. While the Draize test is still widely used, many scientists have developed alternatives. One such technique, called the BCOP test, is a stand-alone method for determining the toxicity of a substance. This method uses cow eyes, which are normally discarded, which can be considered an animal test. PETA raised this issue, and the scientists at IIVS contacted the organization to resolve the issue.

To be effective, in vitro toxicity testing must include several technical challenges. For example, the concentration of the test chemical is often lower than in vivo, leading to an underestimation of environmental risks. Moreover, the in vitro data often produce a PNEC (Predicted No Effect Concentration) value that is far below the in vivo effect concentration. Thus, it is important to have the data on both the in vitro and in vivo toxicity of a chemical.

Moreover, in vitro cytotoxicity assays used in ecotoxicology are not completely comparable to in vivo fish lethality test. The sensitivity difference between the two in vitro assays was two to three orders of magnitude according to the studies by Bols et al. The same is true for in vivo fish lethality testing. Hence, in vitro and in vivo assays are often used for the same purpose.