Cosmetic product safety: old friend or new foe?

Currently, Article 7a of the prevailing European legislation Council Directive 76/768/EEC, merely requires that manufacturers of cosmetic products have readily available an assessment of the safety for human health of the finished product. This safety assessment should include, among other things, the general toxicological profile of the ingredients, their chemical structure and level of exposure. However, the recent recast of the EU cosmetic legislation, Regulation (EC) No 1223/2009, now requires a more detailed safety assessment to be performed for cosmetic products placed on the market from 11 July 2013, the date upon which the Regulation comes into force. Indeed, the Regulation now describes explicitly the specific information that is required to form part of the safety assessment, now called the Cosmetic Product Safety Report (CPSR). Taking its lead from the 7th Revision of the SCCS’s Notes of Guidance for the testing of cosmetic ingredients and their safety evaluation (where the Committee describe the desirable toxicological studies and principles for the safety assessment of cosmetic ingredients and subsequently finished products) Annex I of Regulation 1223/2009 (the CPSR) clearly states that the CPSR should contain the specific details of the toxicological profile of the substances in a cosmetic product for all relevant end-points, with a particular focus on an evaluation of local toxicity such as skin and eye irritation and skin sensitisation, as well as systemic toxicity and corresponding margins of safety if systemic exposure is likely to arise following normal and foreseeable usage of a cosmetic product. Although the clear inference from Annex I is that it is classic toxicity end-points that only need to be considered during a cosmetic product’s safety assessment, the cosmetic action being attributed to ingredients in the 21st century could be considered to be outside of the scope of the SCCS’s Notes of Guidance, for example proteolytic enzymes, peptide growth factors and other metabolic enzyme inhibitors. Recently, it was reported in the online journal, Cosmetic Design (8 February 2012), that researchers in Thailand had isolated and characterised the enzyme bromelain from waste pineapple material following the processing of this plant for food usage. It was reported that pineapple waste such as peel, core, stems and crown contained appreciable amounts of this proteolytic enzyme, which could in turn be commercially beneficial to the pineapple processors. Bromelain is one of a family of proteolytic enzymes isolated from the pineapple plant which among other applications finds usage in the food industry and diagnostic medical laboratories, for example as a meat tenderiser and in blood typing procedures. Its usage as a cosmetic ingredient is somewhat limited though, primarily on the grounds of cost, essentially being limited to oral care or premium skin care products. However, the availability of a cheap and plentiful source of the enzyme could open up its usage in mass market brands for its ‘natural’ exfoliating action. Although the usage of bromelain as a food additive has been reviewed and approved by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) with an Acceptable Daily Intake of ‘Not limited’, in their 15th Report, the Committee acknowledged the possibility of allergic reactions following skin application of enzymes used as food additives.1 However, the possibility of such reactions occurring was subsequently discounted, since the route of exposure was through the diet, which was considered to be equivalent to the normal dietary exposure to proteins and protein fragments. With this in mind, Kelling et al.2 and Sarlo et al.3 evaluated the safety of bacterial proteases as prototype cosmetic ingredients in both rinse-off (soap bar cleansing product) and leave-on applications (moisturiser body lotion). These studies were performed with the knowledge that protease enzyme usage in household laundry products has been shown to produce IgE-mediated hypersensitivity in workers handling detergent enzymes in the occupational setting, primarily through respiratory exposure to enzyme dusts. Both these studies revealed that a number of volunteers developed Type I hypersensitivity to the enzyme in the two prototype products being evaluated, and that respiratory exposure to airborne enzyme was responsible for antibody elicitation. Production of antibody in both studies was also highly time-dependent, taking at least four months of exposure before measurable levels were detected in the blood of volunteers. However, none of the volunteers with elevated antibody titres in either study reported any respiratory symptoms typical of Type I hypersensitivity. Similarly, the only dermal symptoms reported during the studies were considered to be consistent with an irritant response to the prototype products being evaluated. It was subsequently concluded that the induction of the allergic antibody was sufficient grounds to discontinue the development of these prototype proteasecontaining personal care products. Although these studies were performed using purified Bacillus bacterial protease enzymes, occupational respiratory sensitisation has also been reported in medical laboratory workers handling bromelain during their day-to-day work.4 Indeed, Baur and Fruhman5 had earlier reported a confirmed case of occupationally-derived sensitisation to bromelain in a pharmaceutical worker handling purified enzyme over a 10-year period. In this specific case, asthma and rhinitis were also reported by the affected worker concurrently with handling of bromelain at work. In investigating the case, respiratory symptoms were recorded during both respiratory and dietary challenge with unpurified pineapple material. Therefore, although classic toxicological principles and techniques (as described in the SCCS Notes for Guidance) are suggestive of protease enzymes being acceptable as cosmetic ingredients, practical human clinical data reveal the opposite. Consequently, cosmetic safety assessors would be lulled in to a false sense of security if, for example, they only utilised techniques such as read-across to other exposure scenarios such as dietary intake following usage of the enzymes as tenderisers. For protease enzymes, the only definitive way to demonstrate their safety as cosmetic ingredients would be to undertake extensive clinical testing, including invasive blood sampling, which could be considered outside of the scope of the SCCS Notes for Guidance.

Epidermal growth factor

Turning now to the proliferation of skin care products containing peptides depicted as epidermal growth factor (EGF), and described by Hart-Davis in January 2011 as being ‘the next big thing’,6 ingredients which at the very least should be used with caution in the light of their biological action. EGF is one of a family of growth factors, being a polypeptide of 53 amino acids, which possesses the ability to stimulate the growth and differentiation of epithelial tissues, fibroblasts and endothelial cells. This effect is achieved through the molecule binding to specific cell surface EGF receptors, to stimulate mitogenic responses in the target tissue.7 Other effects noted for EGF include stimulation of cell migration and development of new blood vessels within the tissue undergoing repair. Of interest to the cosmetologist is the knowledge that EGF plays a major role in tissue repair and wound healing, in concert with a number of other naturallyoccurring growth factors and cytokines. This observation led ultimately to the development and usage of EGF as a therapeutic agent in the management of wounds and burns, for both internal and external tissue repair. But, and importantly from the cosmetic product safety assessment point of view, these cellular events are also common critical processes in the development of cancerous tumours, which led to concerns about the predisposition of patients being treated with EGF to cancer development. However, the experimental evidence suggests that EGF does not ‘initiate’ tumours, which means it does not transform normal cells in to cancerous cells. Rather, EGF is a ‘promoter’, which means that it will stimulate the growth of cells that have already been transformed in to potential tumour cells. In this context, Berlanga-Acosta J et al.7 reported that the cancer incidence among patients being treated with EGF for the management of burns essentially matched an untreated control group. However, in marked contrast, following a review of data for patients being treated with a recombinant human platelet-derived growth factor for the treatment of diabetic ulcers, USA FDA warned that there was an increased risk of death due to secondary cancerous tumours among patients being treated with the preparation; the types of cancer recorded were varied and remote from the site of treatment with EGF. Consequently, it is now stated in an ‘Important Drug Warning’ issued by the manufacturer of the preparation that this EGF should be used with caution in patients with known malignancy, and that the material should only be used when the benefits can be expected to outweigh the risks.8 Although EGF would be expected not to penetrate the skin into the blood due to its molecular size, clinical studies clearly demonstrate changes in skin structure and morphology in both the epidermis and upper dermis at the site of application.9 Mehta and Fitzpatrick10 state that evidence suggests a double feedback loop exists in the skin whereby keratinocytes stimulate fibroblasts to synthesise growth factors that in turn stimulate keratinocyte proliferation, which in essence acts as an amplification of the initial effects of topically-applied growth factors. With respect to the classic toxicological end-points as described in the SCCS Notes for Guidance, Marachin et al.11 reported the outcome of a toxicology testing programme in various animal models with human urinary EGF. This testing revealed that while urinary human EGF was devoid of mutagenic or teratogenic activity, there were pronounced pharmacological effects which produced severe impairment of the main organ systems, leading to the death of some animals. However, the SCCS Notes for Guidance essentially do not take account of the reputed biological action of cosmetic ingredients. Therefore, the cosmetic toxicologist may not fully appreciate the potential hazard of novel ingredients if the biological action of the cosmetic ingredient under review is not considered during the safety assessment process. Nevertheless, there is also a question mark concerning the regulatory status of the some EGF peptides used as cosmetic ingredients. In North America, the growth factors and cytokines commonly used as cosmetic ingredients are generally produced from cultured human dermal fibroblasts,12,13 making them specifically human-derived. These growth factors would be considered illegal as cosmetic ingredients in the EU, according to EU Directive 76/768 EEC, Annex II, No. 416. This entry specifically prohibits the use of cells, tissues or products of human origin, including RH-oligopeptide-1, which is described as a recombinant human peptide produced by microbial fermentation, where the starting gene has been directly isolated from a human cell. Other biosynthetic routes for EGF production include extraction from cell culture growth media or plant tissue genetically modified to produce human-like growth factors, where a human-identical recombinant gene has been transfected by a vector organism in to a host plant. Therefore, when considering the usage of peptide growth factors such as EGF as cosmetic ingredients, not only should the cosmetic toxicologist consider the regulatory position of such peptides, it is also crucial that a holistic approach is adopted to the safety assessment of the peptide in question, which should include the reputed biological action of the molecule under evaluation.