Ask a RIFM Scientist: Can an egg save animal lives?


The Research Institute for Fragrance Materials (RIFM) is committed to developing scientifically sound ways to evaluate the safety of fragrance ingredients without using animals.

Award-winning scientist Yax Thakkar, MS, leads RIFM’s genotoxicity testing program. This week, we talked with Mr. Thakkar about exciting new research using chicken egg models.

Q: What do chicken eggs have to offer us?

A: Everyone wants products that are safe to use without having to test them on animals.

In 2013, the European Union (EU) implemented a ban that prohibits animal testing for finished cosmetic products and ingredients in cosmetic products, as proposed in the Seventh Amendment to the Cosmetics Directive.

Before the ban went into effect, RIFM developed a set of safety assessment criteria, outlining a series of scientifically rigorous approaches to help ensure that fragrance safety evaluation meets the EU guidelines.

In those exceptionally rare cases where the other approaches are not possible, the chicken egg model offers a promising genotoxicity testing method that avoids in vivo (live animal) experiments.

Q: How does the model work?

A: The egg model uses fertilized eggs from white leghorn chickens, which are a top egg-producing breed in commercial production. Fertilized leghorn eggs take 21 days to hatch. We conduct testing up to day 11, before the chicken embryo develops a fully formed nervous system, to avoid any possible discomfort.

Q: What can these studies tell us about possible genotoxicity?

A: An animal follow-up study is necessary to confirm those rare Petri dish (in vitro) studies that return positive results for DNA mutations (mutagenicity) or chromosome breaks and alterations (clastogenicity). (See last week’s Ask a RIFM Scientist.)
RIFM may conduct egg studies following the same guidelines as confirmation animal studies, with the sole exception being that they would be carried out in eggs rather than in animals.

Q: What can an egg test tell us that a Petri dish test cannot?

A: The egg study can validate the biological relevance of the Petri dish study. For instance, Petri dish studies lack a liver detoxification pathway, which can lead to false-positive results. The egg model includes a liver and the enzymes required for the liver detoxification pathway.

Q: Are there other animal-alternative genotoxicity strategies in use or on the horizon?

A: The primary route of exposure to fragrance ingredients is via the skin. RIFM also supports the use of 3D skin models for both mutagenicity and clastogenicity.

In addition, RIFM is looking at a screening test called ToxTracker. ToxTracker can help us better understand some of the mechanisms behind Petri dish results and, thus, help us choose the most appropriate follow-up tests to assess the biological relevance of Petri dish study outcomes.