Widely used throughout the pharmaceutical, food and cosmetic industries, the Ames test is a legal requirement before drugs, cosmetics, food and packaging items can be safely brought to market and used by the public. So, what does the Ames test do, and why is it necessary to ensure safety?

What is an Ames test?

The Ames test has been in use for decades and is one of the most requested tests to investigate the mutagenic potential of compounds associated with cancer. It is essential to identify any risks of cancer mutation within a compound before development continues. The Ames test uses reverse mutation principles to provide early indications of carcinogenic and mutation properties.

Ames testing may identify whether a chemical could become mutagenic and act as a carcinogen. Cancer is often linked to mutation, and such a test identifies whether a given chemical can cause various changes and mutations within the DNA of the test organism.

The use of this chemical test is a quick, convenient and easily replicated test. In some cases, it can negate the need for standard carcinogen assay testing, previously carried out on rats and mice, taking two to three years to complete, often at a high cost.

Why do we need the Ames test?

Experienced providers of Ames testing, such as Gentronix, will tell you that it has become increasingly important to find suitable alternative strategies for carcinogenicity assessment. Ames testing can be used in isolation or as part of a more comprehensive testing framework to identify the risks and mutations, and may help companies make key decisions on project progression before conducting further animal studies.

Ames testing uses strains of bacteria that may carry a mutation, most commonly Salmonella Typhimurium, to carry out controlled sampling, which can take as little as two days incubation to provide a result. This is more humane and socially acceptable than previous animal testing options. It is also cheaper, more readily controlled and repeated. Ames testing Is also mechanistically amenable to use of adverse outcome pathway analysis.

What industries is Ames testing used in?

Essentially all of them. Industries that provide drugs, cosmetics or foodstuffs to humans and animals are required by law to ensure the safety of such products. They will use the Ames test to assist with determining product viability. The Ames test Is either required or expected to be conducted In almost all regulatory frameworks assessing toxicity to human health.

Testing will also identify when further investigation or control points are required. Early risk identification is critical during product development, and Ames test results can help determine whether further action is safe or viable. Positive or unwanted results can then determine future decisions if a risk is identified. In some cases, identifying a risk may not be the end, as it can be used as a basis for further tests.

How does the Ames test work?

Tester strains are specially constructed to detect either DNA base changes or frameshift mutations in the genes required to synthesize key substances such as histidine, enabling mutagens activating via different mechanisms to be identified.

Mammals have metabolic processes that have the potential to turn a non-mutagenic chemical into one that is. Rat liver enzymes can be added to the Ames testing compound to replicate the metabolic processing effect. Adding limited amounts of histidine to control plates allows bacteria to grow and have an opportunity to mutate. Where such mutation is identified using the Ames test, it is possible to identify many known carcinogens.

Whilst the Ames test identifies the presence of mutagens and therefore the potential for carcinogens, this may not necessarily be the case. Further tests can be carried out to determine where positives may be caused by other factors such as bacterial specific metabolism, , which can provide a false positive or identify a safe level of presence and risk.

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