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Survey and safety assessment of Chemical substances in artificial nails and nail hardeners 4 Chemical Analyses
4.1 Quantification of formaldehyde in nail hardenersIn cooperation with the Danish Environmental Protection Agency, a number of nail hardeners were selected to be analysed for content of formaldehyde. Six of the seven purchased nail hardeners were analysed. As two of the products were of the same brand, only one of them was selected. Thus, all six different brands were represented in the analysis. 4.1.1 Quantitative GC-MS method of analysisBefore breaking the sealing of the sample, the sample is heavily shaken. The next step is to weigh out quickly approx. 1 g to a measuring flask half filled with dichlormethane. The measuring flask is filled up to the marking dicloromethane. The samples are dissolved/extracted during a period of approx. 2 hours. After extraction/dissolution, part of the dichlormethane phase is transferred to GC-vial, whereupon it is ready for analysis. In connection with very viscuous extracts, the sample is appropriately diluted before analysis (typical 10*). The dichloromethane used for the analyses is also used to dilute the sample. Also analyses of blind samples of the dichloromethane used for the analyses are carried out. The extract is analysed on GC-MS-SIM. The following method parameters are used: Oven: Starting temperature 40o C to be kept for 3 minutes, then a slope of 30 o C/minute until 300 o C has been reached. The final temperature is kept for 2 minutes. Injector parameters: 280 o C, split less injection. 2µl injected. Starting pressure 6.0 psi. The method is an internal method used by Analycen. The reference number for internal method is KG.18. Calculation of the content is carried out based on internal standards. The detection limit of the analysis method is determined to be 10 mg/kg, and the analyses uncertainty is 10%. By this method both the content of free formaldehyde and the content of formaldehyde donors were determined. 4.1.2 Results in % of the GC-MS analyseThe quantified content obtained from the performed GC-MS analysis is illustrated in table 4.1. The analyses show that 2 of the analysed 6 products contain more than 2% formaldehyde, whereas the remaining 4 products all contain between 0.01 and 0.8% formaldehyde. The formaldehyde of the two products with the lowest content of formaldehyde (product no. 9 and 20) has not been declared. Table 4.1 Content of formaldehyde (%) in selected nail hardeners analysed in double determination. The indicated content is the average of the double determination. The difference between the two determinations varies less than 3% for all samples except for product identification 20 that varies 9%. Besides it is indicated for each product if formaldehyde is declared (√) or not (-). The detection limit is 0.001%.
4.2 Quantification of acrylic compounds in products for manufacture of artificial nailsIn cooperation with the Environmental Protection Agency, a number of nail products were selected for analysis of content of different acrylic compounds. The products were selected within the categories gel nails, acrylic powders for building up acrylic nails and liquids that are also applied for formation of acrylic nails (see Chapter 3). All three types of products were selected in order to be able to compare and evaluate the degree of health risk of the different systems. During the analyses, the monomers are focused on. In accordance with the safety data sheets, the artificial nail products contain different forms of polymers. Polymers are not particularly interesting with respect to safety, as their toxicity is considered low due to their big size, and very often the data found are very few. On the other hand, polymers may contain small amounts of monomers (the starting material of the polymers) that may have a high toxicity. Therefore the focus in the analyses were the monomers in order to illustrate the levels of monomers in the different products. In cooperation with the Environmental Protection Agency it was determined to test for the following acrylate monomers in the selected products: - triethyleneglycol diacrylate (CAS nr. 1680-21-3) - 2-hydroxypropyl acrylate (CAS nr. 999-61-1) - 2-hydroxyethyl acrylate (CAS nr. 818-61-1) - ethyl acrylate (CAS nr. 140-88-5) - ethylene dimethacrylate (CAS nr. 97-90-5) - 2-hydroxypropyl methacrylate (CAS nr. 27813-02-1) 4.2.1 Method of quantitative GC-MS analysisFor description of methods, please see Chapter 4.1.1. The content was calculated based on internal standards. The detection limit is 10 mg/kg and the uncertainty margin 10%. All analyses were performed in double determination. 4.2.2 Results in % of the GC-MS analysisThe content of acrylic compounds quantified in the GC-MS analysis is shown in table 4.2 – 4.3. Tabel 4.2 Content of acrylic compounds (%) in selected products for gel nails. The indicated content is the average of a double determination. (-) indicates that the substance is below the detection limit of 0.001%.
The analyses for acrylic compounds show that the amount of tested compounds contained in the products for production of artificial nails (acrylic nails and gel nails) is limited. Some products contain 10% of one of the 6 analysed substances, but in all cases only one of the substances is contained in the product in such a great magnitude. Generally, it can be seen that the products for formation of gel nails contain several of the tested acrylic compounds. The analysis shows that the products for manufacture of gel nails generally contain the substance 2-hydroxyethyl acrylate in the highest concentrations (3-8%) and only one product out of seven tested does not contain the substance (table 4.2). Unlike the other products, this product (product number 17) contains mainly 2-hydroxypropyl methacrylate. The other tested acrylic compounds are only found in small amounts (< 0.8%) in the tested products. Except for a small amount of ethylene dimethacrylate found in product no. 25 (0.015%) (table 4.3), none of the tested acrylate compounds were found in the powders for manufacture of acrylic nails. This is somewhat surprising but the reason may be that the content of this type of products are mainly polymers, whereas the content of monomers in the products are low. Based on safety data sheets on the individual products, the ingredients have been identified as different types of polymers such as polyethyl methacrylate, polymethyl methacrylate orcopolymerer of ethyl and methyl methacrylate. By screening the ingredients in the powders, butyl methacrylate has most probably been found in 6 of the seven analysed products (Chapter 4.3.2 – table 4.5). However, no methyl methacrylate and ethyl methacrylate have been found in the powders. This indicates that there is only a very small amount or none of these monomers in the product. In the liquids which together with the powders are used for manufacture of acrylic nails, the amount and type of acrylic compounds vary to some extent between the products. For two of the products, the content of 2-hydroxypropyl methacrylate is found to be approx. 10%, while another product contains 15% ethylene dimethacrylate. From the Safety Data Sheets for a couple of the products it appears that this type of product often contains quite a considerable amount of ethyl methacrylate (up to 80%). An assumed content of ethyl methacrylate was also identified during the screening (Chapter 4.3.2 – table 4.5). Table 4.3 Content of acrylic compounds (%) in selected product for building up acrylic nails divided into powders and liquids. The indicated content is the average of a double determination. (-) indicates that the substance is below the detection limit of 0.001%.
4.3 Screening for ingredients in products for manufacture of artificial nailsThe quantitative analyses for acrylic compounds showed that it is very obvious that the nail products contain other ingredients than the analysed 6 acrylic compounds due to the fact that the GC-MS analysis showed many other peaks in the mass spectres than the 6 acrylic compounds. Consequently it was decided to perform a screening (GC-MS-SCAN) of the ingredients that appeared with the highest peasks in GC-MS based on the quantitative analyses. With a reasonable probability it will be possible by this method to assume the ingredients of the highest peaks. 4.3.1 Principle of analysesA well-known amount of sample is diluted/extracted with dichlormethane. The extract is analysed using the GC-MS-SCAN. During the analysis the mass- spectres of the substances contained in the sample are absorbed. Different substances have different mass-spectres; however isomers (for instance xylenes) may have (almost) identical mass-spectres. The absorbed mass-spectres can be compared with the mass-spectres in a library containing more than 100,000 mass-spectres. Based on the congruity between the absorbed spectres and the spectres of the library, the possible substance is suggested. Also the library shows a quality assessment of the suggested substance. This is indicated as a number between 0 and 100. The closer to 100 the better is the congruity, and the greater the probability that the suggestion is correct. The laboratory has experienced that suggestions of a quality above 80 are often correct. However it should be emphasized that it cannot be finally verified, until a standard containing the suggested substance has been analysed. Table 4.4 and 4.5 show the components that have been suggested using GC-MS-SCAN through library search. The number of suggested components varies from 1 to 6. The tables do NOT reflect the complete number of components in the products, on the contrary it is estimated that by far the most products contain between 50 and 100 components. 4.3.2 Screening results21 products to be applied for artificial nails (acrylic nails and gel nails) were screened for ingredients. Each product has been screened for the ingredients showing the highest peaks during the quantitative GC-MS analyses for acrylic compounds. Table 4.4 Screening of ingredients in selected products for gel nails.
Table 4.5 Screening of ingredients in selected products for acrylic nails (powders)
Table 4.6 Screening of ingredients in selected products for acrylic nails (liquids)
4.4 Quantification of benzophenon or azobenzenIn connection with screening for ingredients, a product was assumed to possibly contain azobenzene, which is classified as mutagenic and carcinogenic (see table 5.1). Therefore there was a need to state if the product contained the substance, or if it was benzophenon. 4.4.1 Method of analysis for quantitative GC-MS methodPlease refer to Chapter 4.1.1 for description of the GC-MS analysis method. The content was calculated based on internal standards. The detection limit is 10 mg/kg and the uncertainty 10%. All analyses were performed in double determination. 4.4.2 Results in % of the GC-MS analysisThe quantified content obtained from the GC-MS analysis is illustrated in table 4.7. The analyses show that the gel product contained benzophenon and not the cacinogenic azobenzene. Table 4.7 Content of benzophenon (%) and azobenzene in selected gel nail products. The indicated content is the average of a double determination. The detection limit of the analysis amounted to 0.01%. (-) indicates that the substance is below the detection limit of 0.001%.
4.5 Selection of substances for safety assessmentBased on the analyses performed on nail hardeners and products for manufacture of artificial nails, the substances to be toxicologically assessed were selected in cooperation with the Danish Environmental Protection Agency. The following substances were selected: - Formaldehyde (in nail hardeners) - 2-Hydroxyethyl acrylate (in gel nails) - 2-Hydroxypropyl acrylate (in gel nails) - 2-Hydroxypropyl methacrylate (in liquid and gel nails) - Ethylene dimethacrylate (in liquid and gel nails) Footnotes[1] No reliable hits appear, but the sample is assumed to contain up to 100 components.
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