October 12, 2006

Sensory Irritation During Use of Hair Color Product and Explanation ofSkin Characteristics that Increase Susceptibility to Sensory Irritation:
An Evaluation Method Established by Mandom.
Mandom Corporation (Head Office: Osaka, President Executive Officer: Motonobu Nishimura, hereafter“Mandom”) has independently established a technique for appropriately evaluating sensory irritation that isexperienced when using hair color (oxidative hair dye).
Additionally, we have identified and explained the skin characteristics that make one susceptible to thesensory irritation that occurs as a result of using hair color (oxidative hair dye). We expect that this will enable
us to ensure that our customers can use our products more comfortably than ever before.
We plan on presenting our research achievements at the International Federation of Societies of Cosmetic
Chemists (IFSCC) Osaka Conference that is held on October 16-19.
<Research Background: In Order to Ensure Comfortable Use of Hair Color>
Over the last ten years, hair color’s (oxidative hair dye) place in the world of fashion as the substance ofchoice for changing one’s hair color has been solidified. However, there are a few rare cases in which
individuals choose to stop using hair color because of an uncomfortable tingling, prickly, or pain-like sensationthat is experienced when hair color products come into contact with their skin. From our understanding, thisunpleasant tingling is not an allergic reaction to dyes present in the product; instead, it is caused by alkali andhydrogen peroxide.
In order to enable consumers to comfortably use cosmetic products, a great deal of research has been
conducted on sensitive skin—skin prone to experiencing this sensory irritation. Further, in order to enableconsumers to understand criteria by which they can choose a product most suited to their skin and hair needs
before use, we list all the compounds that are used in our cosmetic products on their labels. However, because
hair color is a product for hair, not skin, almost no research has been done on its dermatological effects. Thus,in order to ensure that as many people as possible are able to use hair color products comfortably, Mandom hasdeveloped and explained—through research—a method to evaluate the sensory irritation that is experienced
when using hair color products, as well as a list of characteristics of the skin types that are most likely toexperience this sensory irritation.
<Evaluation Methods for the Sensory Irritation>
Common methods for evaluating sensory irritation include patch tests, in which the product is tested against
their inner arm, and use tests, in which one actually uses the hair color product to dye their hair. However,
because evaluation of sensory irritation varies wildly with patch tests and because use tests cannot be performed
many times across a large group of people (their hair color will change), the most appropriate evaluation
method has yet to be found. As a result, it has been incredibly difficult to prevent against the rare occurrence of
this sensory irritation. Thus, in order to develop a method suited to multiple experiments, we carried out anexperiment with a total of twenty men and women as our subjects. We found that evaluating the hair color
product on the back of the neck enabled subjects to most appropriately evaluate their experience of the sensory

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-1-irritation (refer to Table 1, Figure 1). We believe that the reason for these results is that the distribution ofnerves in the scalp and neck is quite similar.
Figure 1: Appearance of a Sensory
Irritation Test

Table 1: Survey of Sensitivity to Hair Color(on Multiple Parts of the Body)

Back of the Head

Decided thata higher amountof the irritating
compound(containing morealkali) hurt more
76%

Decided thata lower amountof the irritating
compound(containing lessalkali) hurt more
6%

Back of the Neck80%

20%

0%

Inner Arm

17%

34%

49%

Outer Arm

38%

25%

37%

Part

Could notdifferentiate

18%<Characteristics of Skin Prone to Experiencing Sensory Irritation>
While conducting experiments on the sensitivity of the back of the neck to sensory irritation, we alsomeasured the skin characteristics of forty-six male subjects to determine the characteristics exhibited byindividuals that were most sensitive to sensory irritation. This evaluation was conducted over the course of two
experiments in June and October 2005. As a result, we discovered that subjects with the following
characteristics were particularly susceptible to sensory irritation:  low skin moisture barrier strength,  low
sebaceous secretion (easily dried, flaky skin),  low skin surface temperature, and  high skin catalase(enzyme that breaks down hydrogen peroxide, an ingredient in hair color) activity (refer to Figure 2).
By identifying the characteristics of sensitive skin using this method, we are able to provide appropriate andapplicable advice to enable consumers to use hair color comfortably, such as the following: “To avoid dryingout your scalp and hair, try to wash it as gently as possible the day before,” and “Do not color hair when yourscalp is damaged, such as when it has been sunburned.”
Hereafter, we plan to research the relationship between skin surface temperature and enzymatic activity tocontinue developing comfortable products and useful advice for our consumers.

Sensitive
individuals

Insensitive
individuals

Sensitive
individuals

Insensitive
individuals

Catalase activity High
Low

Low

Low

Sebum amount

Moisture
barrier strength HighHigh

Low Surface temperature High

Figure 2: Skin Characteristics of Individuals Prone to Experiencing Sensory Irritation when
Using Hair Color Products

Sensitive
individuals

Insensitiveindividuals

Sensitiveindividuals

Insensitive
individuals

Moisture barrier strength: reciprocal of transepidermal water loss; Sebum amount: Amountof sebum secreted in 20 sminutes; Surface temperature: skin surface temperature; Catalase
activity: catalase activity on exfoliated skin measured via colorimetric test-2-

<Future Applications to Hair Color Products>
Based on the results of this research, Mandom will test all of its currently marketed products using theaforementioned sensory irritation tests and will continue to only market products that meet certain comfort
standards. Unlike the outcome of our older evaluation methods, the number of claims of pain and discomfort wehave received from customers have gone down significantly, confirming the results of our research. In thefuture, we plan to continue releasing hair color products that consumers can safely and comfortably use.
Finally, we would like to indicate that we expect our current research to lessen only the sensory irritationassociated with the use of hair color products, not allergic reactions to hair color products. In order to prevent
allergic reactions, the Japan Hair Color Industry Association advises “individuals who have experienced rashes
due to hair dyes” and “individuals who have felt sick after using hair dyes” to avoid using hair color products.
We publicize these guidelines on our hair color products and have not changed our belief that individuals thatare susceptible to allergic reactions avoid using hair color products.
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