The Ames Assay has been the standard genotoxicity test for assessing the safety of food contact materials (FCMs) for decades. In this article, Gentronix looks at the exact role the Ames Assay plays in ensuring the packaging they use for food does not cause an unacceptable risk to human health. The Ames test also checks the safety of other substances that may have been inadvertently, which could migrate into food and be eaten by the consumer.
Protecting food and our health
FCMs such as tin cans and Styrofoam cups are typically used to protect food and are therefore required to be stable, to ensure that they themselves cause us no harm. The Ames test was to help assess non-intentionally added substances (NIAS) that might occur in FCMs, either as contaminants of the starting materials or breakdown products during manufacture.
The Ames test seeks to ensure that substances leaching from food wrappings are of low risk of leading to potential mutagenic outcomes, such as cancer.
What the Ames Assay?
A positive Ames test result indicates that the chemicals tested have mutagenic potential and have the ability to change human DNA. If this is the case, they may have the potential to cause cancer. Cancer is often linked to chemical mutations, and therefore the purpose of the Ames test is to identify substances that have this potential. Those manufacturing FCMs will be mindful of the research into carcinogens and containers, and will want to ensure that their products do not harm their users.
This test is quicker and cheaper to perform and produce results over standard carcinogenicity testing on mice and rats, which takes in the region of two to three years to complete. Aside from being a non-animal approach, it also uses a fraction of the test item which is a significant logistical limitation in some circumstances. The Ames test has been effectively used to identify hundreds of genotoxic carcinogens, including many of the most potent.
Identifying NIAS presents a challenge because they are typically only present in low concentrations; it is not practicable to identify and test every substance that originates from FCMs.
The Ames test uses several bacteria strains, with mutations at specific loci, and an increase in growth of bacterial colonies shows that the tested chemical under these test conditions causes mutations, thus requiring further investigation.
Lowest effective dose in the Ames test
Gentronix, offering the Ames test as part of broader assay testing, in conjunction with Lhasa Limited looked to determine at what level FCM migration an Ames test would provide a positive result if present at regulated limits of 90 ppb. Findings did show that the lowest dose to give a positive Ames test result was found to be as low as one ng/plate for some data sets and showed the Ames test can detect potent mutagens at low concentrations but in higher doses.
No other assay was found to be more sensitive when judged by lowest effective doses than the Ames test, which is why this cost-effective test is used so widely to ensure that FCMs do not cause harm to our health.
Image Credits: Aline Ponce