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Survey of chemical substances in headphones and hearing protection aids 11 Proposal for analysis and assessment programme
As described in the general assessment of potentially health risks there is no indication that use of headphones and hearing protection aids constitutes a specific or significant risk for the consumers. The basis of this general assessment is that similar exposure situations (exposure for same or similar materials, primary exposure via skin contact, comparable duration of the exposure) for other product types cause an exposure for single substances for which the Margin of Safety (MoS) in most cases is very high. From the general material descriptions it is also seen that in general all plastic materials are modified by using additives which give the materials the desired properties in a given application. The selection of additives which can be applied alone or in combination with others is very large – there are thousands of additives in use today – and I can of course not be ruled out that some of these can give occasion for an exposure to hazardous substances which can imply a risk for the consumer. Basically there must, however, be significantly higher amounts in the products than it was the case for the analyzed products described in section 8.3.2. A more precise knowledge can be obtained through a project with an approach corresponding to that used in surveys of school bags, pencil cases, rubber erasers etc. Due to a very low or improbable exposure through inhalation or oral intake it is not recommended to analyse and assess emission of substances to the air or to analyse and assess health risks due to oral intake. Analysis and assessment are thus limited to exposure via the skin of migrating substances and are carried through according to the following outline where focus is on substances and groups of substances which are identified as interesting, e.g. due to a high content, large skin penetration or the health properties. 11.1 Selection of productsThe products which are purchased in the present project are in general judged to be sufficiently representative for the two product groups and therefore they can be used in an additional project if desired. However, it shall be noticed that it is doubtful that the purchased headphones will also be available on the market when a future project is completed. From the purchased products eight are selected for a more detailed analysis:
Alternatively, it can be decided to purchase new products and analyze these by means of FT-IR like in the present project and thereafter select eight products which reflect the material used in the purchased products in an appropriate manner. 11.2 Migration of substances with artificial sweatTo identify the substances which can get into contact with the consumer we suggest carrying out a migration test to artificial sweat. Artificial sweat for the migration tests is produced according to the standard EN1811. It is recommended that the migration test focuses on the materials which are in contact with the skin in and around the ear. Alternatively, the total amount of the chemicals in the products can be determined, through extraction with suitable solvents. This gives a picture of which substances that potentially can be found in the sweat and therefore should be quantified, but it does not in itself indicate which substances can migrate and possibly give a health impact. 11.3 Analyses of constituentsAn identification and quantification of the following substances and groups of substances is judged to give a good overview of the health impacts which consumers face when using headphones and hearing protection aids. The analyses mentioned below will each give a number of information about constituents in the materials for which reason, with certain exceptions, they are relevant for all the identified materials for headphones. Organic compounds – general analysis: The migration extract is up-concentrated with SPE or shaking with DCM and the resulting extracts are analyzed semi-quantitatively by chromatography with mass spectrometric detector (GC-MS). For the GC-MS analyses, Varian Saturn 2000 ion-trap GC-MS system can for instance be used. Through this method, the presence of phthalates can be verified and light stabilizers and certain dyes may be identified. The content is calculated to relevant standards. Organic tin compounds: The migration extract is shaken in aqueous medium and is derivated through an extractive derivation with sodium tetraethyl borate and pentane. Iso-octane is added to the organic phase, which is up-concentrated and analyzed with combined gas chromatography and mass spectrometry (GC/MS) through selective ion monitoring of the substances in question. The content is calculated to relevant standards. Organic tin compounds are primarily applied as stabilizer in PVC products and therefore it is especially interesting to analyze for the content of these compounds if the basic material is PVC. Brominated flame retardants: The migration extract is cleaned in an aluminium oxide column and is analyzed through combined gas chromatography and mass spectrometry (GC/MS). Quantification is made through isotope dilution technique. Tetra bromine phenol A (TBBPA) is analyzed by using fluid chromatography with UV detection (HPLC/DAD). TBBPA which is bound in the polymer chain is not expected to migrate. Isocyanates and amines: The migration extract is added dibutylamine (DBA) for derivation of possible di-isocyanates. Before the anylysis, ethyl chloro formiate for derivation of the diamines is added. Thus, diamines are determined as carbamates. The analyses are carried out through combined fluid chromatography and mass spectrometry (LC/MS). Isocyanates and amines can be present in products of PUR, being a residue from the production. Therefore, it is primarily in products of PUR it would be interesting to analyze for isocyantes and amines. The content of metals (suggestion: chromium cobalt, arsenic, selenium, antimony, cadmium, barium, mercury and lead) is determined quantitatively by analyzing the migration extracts by means of ICP-MS. 11.4 Health assessmentIn consultation with the Danish Environmental Protection Agency 7-10 single substances identified through migration to artificial sweat are selected for a health assessment. A primary selection criterion is that the substances are absorbed through the skin which is the only relevant way of exposure. Secondly, focus ought to be on the substances which from already completed toxicological assessments and risk assessments at international and national level (e.g. EU, ATSDR, IRIS, IPCS, WHO) are known to constitute a risk for the consumers’ health. Substances with a known sensitizing effect ought to be included in the additional assessment if they are identified in the analyses. The most precise assessment of systemic effects is reached in relation to the substances where the critical effect is known and a NOAEL (No Observable Adverse Effect Level) is established but in any circumstances the assessment must be carried out according to the guidelines in the EU’s Technical Guidance Document, which has been used in the surveys of a wide range of other consumer products. Thus, the result of this assessment is an overview of the potential health effects for the selected substances and a suggestion of which exposures that are assessed to be without any effect on humans. However, it shall be noticed that the outlined procedure does not give any possibility of assessing a possible risk of allergy. EU’s Technical Guidance Document only gives a very general guidance in the assessment of the risk of sensitisation. However, it would be a natural element to follow the guidelines by giving a pragmatic, qualitative assessment of the risk of allergy by using existing knowledge about the sensitizing properties and, where possible, knowledge about the connection between concentration and effect.
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