|
Survey of chemical substances in cleaning products for ovens, cookers and ceramic cooktops 4 Chemical analyses
4.1 Selection of products for chemical analysisAs the knowledge of contents and concentrations of chemical substances in oven and cooktop cleaners is limited, a number of the products identified in the survey were selected for analysis for specific constituents. The following selection criteria for the products for analysis were established in concert with the Danish EPA:
All the surfactants that were identifiable in the products were assessed to be completely biodegradable. Surfactants were thus not included in the analytical programme. Several of the retail products contained fragrances. A large number of fragrances are currently in focus because of their allergenic effects. As they are not leave-on products, where users are frequently exposed via skin contact, and as exposure to fragrances in oven and ceramic cooktop cleaners is considered to be limited compared to the total exposure to fragrances in consumer products, analyses for fragrances were not included. Based on the preliminary survey of the chemical constituents in oven and ceramic cooktop cleaners, 14 of 21 products were selected for chemical analysis. All 14 products were analysed for their contents of solvents, while 4 of the products were also analysed for their contents of PFOS (perfluoroctanyl sulfonate) compounds. Table 4.1 shows the selected product types.
4.1.1 SolventsSolvents are used in oven and ceramic cooktop cleaners in order to dissolve grime and grease. Furthermore, solvents improve the effect of surfactants in the products. As smudging will usually be more pronounced in ovens and on ceramic cooktops compared to other surfaces, the concentration of solvents in oven and ceramic cooktop cleaners may be expected to be higher or the composition of solvents may be different from that of common cleaning agents. 4.1.2 PFOS compoundsPFOS compounds and their metabolites are persistent in the environment. All PFOS compounds may potentially degrade to perfluorooctyl sulfonate, which degrades very slowly in the environment, and may bioaccumulate in animals and humans. PFOS is still used in cleaning agents as spray for cleaning of glass (perfluoroalkyl sulfonate) and in a number of polishing products /8/. PFOS compounds have surface-active as well as polishing properties. PFOS increases the fluidity of the product, which makes the product disperse evenly. The function of PFOS is thus an increase of the cleaning effect and the adhesion. In most of the cleaning products, in which PFOS has a polishing or impregnating function, PFOS may be replaced by silicone-based substances, which have a similar function in the products. The majority of the products for cleaning of ceramic cooktops contained silicone substances according to their listings of ingredients. Only the products, for which silicone substances did not appear from their listings of ingredients, were analysed for their potential contents of PFOS compounds. 4.2 Analytical methods4.2.1 SolventsA subsample was extracted with DMF (dimethyl formamide) with addition of internal standards. A subsample of the extract was taken out and directly analysed by combining gas chromatography and mass spectrometry (GC/MS) by scanning a larger mass area. All identifications of substances were made on the basis of the mass spectrum compared with mass spectra in a data library. The contents were calculated quantitatively by use of an external standard and response factors for external standards. For spray products with contents of propellants (propane/butane), the analysis was made after the propellant had evaporated. Analyses were made as repeat determinations and were calculated as the mean of the two determinations. The reporting limit was 500 mg kg -1 and the analytical uncertainty was approx. 15 % RSD (relative standard deviation). 4.2.2 PFOSA subsample was extracted with methanol followed by direct analysis of the extract by reverse phase column liquid chromatography with mass spectrometric detector (HPLC-MS). The detection was made by electrospray ionization in negative mode. The calibration was made with external standards analysed in series with the sample. One of the samples (product no. 7) was not dissolvable/suspendable in methanol. Instead a mixture of methanol and aqueous ammonium acetate was used. The analyses were made as repeat determinations and were calculated as the mean of the two determinations. The detection limit was 0.1 mg kg -1 and the analytical uncertainty was 10 - 15 % RSD. The analysis included the following components: Perfluorobutane sulfonate, perfluorohexane sulfonate, perfluorooctan sulfonate, perfluorodecane sulfonate, perfluorooctane sulfonamide, N-ethyl perfluorooctane sulfonamide, perfluoroheptane acid, perfluorooctane acid and perfluorononane acid. 4.3 Results4.3.1 SolventsAll 14 products were analysed for solvents. Table 4.2 shows the results of the analyses. Values are given in weight percentages. In two of the products (nos. 2 and 9), no solvents could be detected.
-: less than the stated detection limit (500 mg/kg) 4.3.2 PFOSFour of the products were analysed for 9 specific PFOS compounds. No PFOS compounds were detectable in any of the four products (detection limit: 0.1 mg kg -1). 4.4 Summary of results of analyses4.4.1 SolventsSolvents form part of the analysed products in varying concentrations. Table 4.3 shows the sum of the solvents identified by analysing products for cleaning of ovens and ceramic cooktops, respectively.
Note: Analyses of spray products have been made after evaporation of the propellant As expected, the products for cleaning of ovens contained the highest concentrations of solvents, up to 33 % based on weight. According to the analyses, the oven cleaners on spray form had high contents of organic solvents (13 – 33 %), whereas the two other oven cleaners contained < 1 % or no organic solvents. For spray products the real concentration of solvents in the total product, including the propellant, is lower than shown in Table 4.3, as the analysis as mentioned was made after evaporation of the propellant. In the products for ceramic cooktops, organic solvents were identified in 8 of the 9 analysed products. In product no. 2, no solvents were identified by chemical analysis. The solvents were found in concentrations of 0.56 - 13 % (based on weight). Of the solvents identified by analyses, six of the substances were classified in accordance with the Danish EPA’s List of dangerous substances (LODS) as stated in Table 4.4.
* Lower concentration limit for classification of product: 10 % In product no. 1 (oven cleaner, spray), the contents of N-methyl-2-pyrrolidone were measured to 15 % after evaporation of the propellant. The amount of propellant is stated in the safety data sheet to be max. 10 %, which gives a concentration of N-methyl-2-pyrrolidone of 13.5 % in the total product, including the propellant. A product must be classified and labelled as ‘Irritant’ (Xi) when the contents of N-methyl-2-pyrrolidone are more than 10 %. In accordance with the 31st adaptation to the Dangerous Substance Directive (67/548/EC), which has not yet been adopted, it has been discussed to classify N-methyl-2-pyrrolidone as reproduction toxic (T;R61 May cause harm to the unborn child), and consequently also products containing N-methyl-2-pyrrolidone. Product No. 3 contains 13 % of petroleum. For products with a viscosity of less than 7 ´ 10-6 m² sec -1, a petroleum content of > 10 % will result in a classification of a product as “Harmful” (Xn) with R65 (Harmful: may cause lung damage if swallowed). As the product, however, is a cream product with high viscosity, the product will not have to be classified due to its contents of petroleum. None of the other solvents in Table 4.4 are contained in concentrations resulting in a classification of the products. 4.4.2 PFOS compoundsNo contents of PFOS compounds above the detection limit (0.1 mg/kg) were found in any of the 4 analysed products (products nos. 7, 13, 14 and 16). All of the analysed products are ceramic cooktop cleaners. According to their listings of ingredients, the other products for cleaning of ceramic cooktops (not analysed for PFOS) contained silicone compounds (polydimethyl siloxanes). As already mentioned, silicone compounds have the same function in the products as PFOS compounds, and are used as an alternative to PFOS. 4.5 Summary of results of chemical analyses and available product informationIn Table 4.5, the results of the chemical analyses are compared with the information on the composition of the products found in their listings of ingredients and in their safety data sheets (SDS). For each product, comments are made on the concord of these data.
SDS: Safety data sheet Table 4.5 shows that a few of the available listings of ingredients do not agree with the analytical data on solvents. In general, no large amounts of dangerous substances were identified by the analyses. For several products, the results of the chemical analysis are the only data, as no information was available on the product labels or in the safety data sheets (SDS). Aromatic/aliphatic hydrocarbons were identified as petroleum, N-methyl-2-pyrrolidone or alkylised furandione in five of the products (nos. 1, 3, 5, 8 and 13). The analysed parameters indicate that the share and composition of solvents vary according to the application area and form of a product. The highest concentrations of organic solvents were thus found in spray products for oven cleaning, whereas the concentrations in the other analysed produces were lower. The data material, however, is not extensive enough to draw unambiguous conclusions on the composition and contents of solvents according to the different types of products. 4.6 Comparison with scouring creamA sub-objective of this survey and the chemical analyses of oven and ceramic cooktop cleaners were to compare the contents of ceramic cooktop cleaners with common scouring creams. The purpose of this comparison was to assess whether it is the same substances that form part of these two types of products, especially with respect to the use of abrasives. Depending on the grain size of the abrasive particles, the abrasives may scratch the surfaces cleaned. For this purpose, three common scouring creams were purchased in May - July 2005. Table 4.6 shows the typical constituents of scouring creams identified on the basis of the listings of ingredients of the three products.
* According to its listing of ingredients, > 30 % water and calcium carbonate form part of the product Table 4.6 indicates a certain coincidence of chemical substances used in scouring creams and ceramic cooktop cleaners, respectively, e.g. regarding surfactants (surface-active substances). The available information on the specific composition of the products is, however, limited and the comparison is only based on a small number of products. It is thus possible that the overlap in the contents of chemical substances is even larger than indicated in Table 4.6. A substantial difference between the two types of products is that silicone does not form part of the scouring creams. The concentration of solvents in scouring creams is only stated for one of three products, which contains less than 5 % of solvent. If this level is representative of scouring creams, it corresponds to the average concentration of solvents quantified in ceramic cooktop cleaners (4.8 %), see Table 4.3. Various abrasives are used for scouring creams and ceramic cooktop cleaners. In scouring creams, calcium carbonate (chalk) is typically used in considerable amounts together with aluminium silicate. In ceramic cooktop cleaners, mainly aluminium oxide and potassium carbonate (potash) are applied as shown in Table 4.7.
* According to its listing of ingredients, > 30 % water and calcium carbonate form part of the product It was not possible to get any information on the grain size of the different abrasives. It appears that in both types of products, abrasives may constitute a considerable part. For all of the purchased scouring creams, the labels specifically states that the products should not be used for ceramic cooktops and number of other surfaces (i.e. chromium-plated tabs, painted/lacquered surfaces, plastic, marble etc.). The possible applications of the scouring creams are limited to hard surfaces such as tiles, stainless steel, enamel, bathtubs and sanitary ware etc. It is thus assumed that the abrasives contained in common scouring creams may scratch the surface of ceramic cooktops and surfaces that are “softer” than enamel, stainless steel and tiles etc.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||