4. What fragrance substances can be classified as skin allergens?
- 4.1 What sources of information have been taken into account for the SCCS opinion?
- 4.2 What are the findings from clinical and epidemiological studies?
- 4.3 What are the findings from studies in animals?
- 4.4 Can the chemical structure of a substance help predict if it is an allergen?
4.1 What sources of information have been taken into account for the SCCS opinion?
The present opinion by the Scientific Committee on Consumer Safety (SCCS) updates a 1999 opinion by the Scientific Committee on Cosmetic Products and Non-Food Products (SCCNFP) using a systematic and critical review of the scientific literature to identify fragrance allergens, including natural extracts, relevant to consumers. A well-defined search strategy was established to retrieve pertinent clinical/epidemiological and experimental studies. This was complemented, where necessary, with SAR modelling. The evidence was evaluated according to clearly defined criteria and the substances were then categorised as (i) established contact allergens (in humans or animals), (ii) likely contact allergens or (iii) possible contact allergens. More...
|Category||Number of individual fragrences||Number of natural extracts||Lists of substances||Conclusion concerning labelling of consumer products|
|Established in humans||54||28||82 substances (13.1
|Established in animals||18||1||19 substances (13.2
|Likely||26||26 Substances (13.3
|Possible||35||13||48 substances (13.4
4.2 What are the findings from clinical and epidemiological studies?
Based on the results of clinical/epidemiological studies, the SCCS identified a total of 54 individual chemicals and 28 natural extracts (essential oils) that can be categorised as ‘established contact allergens in humans’. Of these, 12 are of special concern due to the high number of reported cases. One ingredient in particular stands out, hydroxyisohexyl 3-cyclohexene carboxaldehyde (HICC), having caused more than 1,500 reported cases of sensitisation in humans since the 1999 SCCNFP publication. More...
4.3 What are the findings from studies in animals?
Where human data are lacking or are considered to be insufficient, animal studies such as the local lymph node assay (LLNA) in the mouse or guinea pig assays (GPMT, Buehler test) can provide important information on the skin sensitising potential and potency of fragrance substances (other types of animal studies are also available). Results from animal testing (mainly LLNA) were available for approximately 70 fragrance substances. Based on this data and in combination with human evidence where possible, 18 individual chemicals and 1 natural extract were categorised by the SCCS as ‘established contact allergens in animals’. More...
4.4 Can the chemical structure of a substance help predict if it is an allergen?
The ability of a chemical to react with and bind to proteins in the skin, either directly or after activation, determines the chemicals’ potential to be a skin sensitizer. The relationship between molecular structure and protein reactivity is based on well-established principles of mechanic organic chemistry and forms the basis for identifying structural alerts by existing structure activity relationship (SAR) computer models. While significant progress has been made in the area of SAR modelling, the computer-based methodology alone is not considered to be sufficient for the identification of skin allergens. Nevertheless, SAR can be used in combination with human and animal data to make useful predictions. Based on a combination of evidence, the SCCS determined 26 individual chemicals categorised as ‘likely contact allergens’ and 35 individual chemicals plus 13 natural extracts categorised as ‘possible contacts allergens’. More...