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Smells Good—But is it Safe?


By: Steve Herman
Posted: February 6, 2013, from the March 2013 issue of GCI Magazine.

“The safety of the people shall be the highest law.”
—Marcus Tullius Cicero

Once upon a time, a bottle of fragrance sent by an eager fragrance supplier sat in the lab. The formulating chemist and development team made a new product, and the fragrance was added. It smelled good, it was stable, and the price was right, so off to market it went. Then another base was created at a later date, and the same process was followed and on and on, whether it was a lotion, eye cream, shampoo or anything else needing a pleasing scent. So the same fragrance oil was used in many different products at different percentages without a thought of regulatory compliance. This, however, hasn’t been the case for quite a long time, but still the nitty-gritty of fragrance guidelines is a mystery to many beauty product developers and marketers.

Adding Fragrance

There are many regulations governing fragrances—they are, after all, mixtures of chemicals. But from the fragrance industry itself comes one fundamental set of guidelines, issued by the International Fragrance Association (IFRA) based on science generated by the Research Institute for Fragrance Materials (RIFM). The levels of safe use are generated by what looks like an algebraic formula, but actually incorporates toxicological complexities of serious proportions:


Where AEL = Acceptable Exposure Level, WoE = Weight of Evidence, NESIL = No Expected Sensitization Induction Level and SAF = Sensitization Assessment Factor.

If it looks like a formula and all the acronyms are decoded, it should be understandable. But WoE NESIL involves the nuanced approach to toxicology used by RIFM, and nuances are not always easy to grasp by the uninitiated.

RIFM has a huge database (available through subscription) of everything known about the safety of fragrance materials. This database is a monumental achievement and a shining symbol of the industry’s commitment to safety. When assembling the data, sometimes gaps are found, which RIFM fills by additional testing or use of whatever methods are applicable, including computer models and structural analogies.

All this data is placed before an RIFM Expert Panel (REXPAN), a group of independent academics, scientists and physicians from around the world. Their evaluation of a safe use level based on all this information becomes the WoE NESIL, the best estimate for the safe use level for the material. So the safe use level is not a fact like the average distance from the earth to the moon, but an expert consensus on the interpretation of all the available information on a given material.

But toxicologists are wary folks, and it is their wont to increase the safety margin by dividing the calculated safe use level by yet another number, the Safety Assessment Factor, or SAF. One factor takes into account the differences between individuals. Then a factor is assigned to the product matrix, and another to use considerations—for example, the underarm versus the top of the head. Thus if REXPAN concludes a fragrance material with a certain end use is safe at 10%, the final guideline may include an SAF of 100 and specify a maximum use of 0.10%. This final value is the AEL, the fragrance level not expected to induce an allergic response.

This data goes to IFRA, and every two years new amendments are made to the guidelines. This information is not a fragrance industry secret; it is all posted on the IFRA website.1