2. How was the Danish study on phthalates in school supplies conducted?
- 2.1 What was the methodology followed?
- 2.2 What are the weaknesses of the Danish study?
2.1 What was the methodology followed?
The SCHER opinion states:
A number of items, including erasers, were analysed for chemical content.
Source: Allen Pope
3.1. General Description of the Danish EPA study
The Danish Environmental Protection Agency investigated the exposure and possible risk of chemicals in consumer products and articles. Within this program, a “Survey as well as health assessment of chemical substances in school bags, toy bags, pencil cases and erasers” has been performed. After a market survey, a number of school bags, toy bags, pencil cases and erasers were purchased and analysed. The chemical analysis was of a screening character and was performed in a tiered approach. The content of chlorine in the articles was investigated to identify PVC-containing articles, Fourier Transform InfraRed (FT-IR) spectroscopy was used on some samples to characterise polymer types, and X-ray analysis assessed the presence of chlorine or bromine (indicative of the presence of flame retardants), and of tin, sulphur and nickel. Head-space analyses were performed to investigate release of volatile chemicals. Extracts of some of the articles were analysed for selected metals, colouring agents, anti-oxidants and perfluorinated compounds. The migration of substances to artificial sweat and saliva was also studied for some of the samples.
A quantitative assessment of the content of chemicals was performed in 46 products including 26 erasers. There is some uncertainty regarding sample 16 as it is identified as pencil case in Table 2.3, but it is used in the risk assessment of erasers. Nine of the erasers contained phthalates; three of them contained 22-44% of DEHP and six contained 32-70% DINP. Some of the investigated products also contained DIBP and di- n-butyl phthalate (DNBP), as indicated by the migration analysis, but the total content of these phthalates was not determined.
The migration of chemicals from 14 products (none of these were erasers) into artificial sweat was studied for 2 g samples into 25 ml artificial sweat at 40°C under static conditions. Detailed information regarding the surface area of the samples is not given, the surface area was “varying”. The migrated chemicals were analysed by GC-MS employing solid phase micro extraction. The results showed that DIBP (maximum 88 µg/g/h), and DEHP (maximum 6 µg/g/h) migrated from 11 and 5 products respectively.
The resulting exposure estimates for some of the identified substances were integrated in a health risk assessment. The conclusion in the report is that, in general, the investigated exposures do not present a health risks for the children. The only exception was exposure to DEHP from erasers through sucking and chewing. In a separate memorandum entitled “Erasers containing DEHP” (Danish EPA, 22 June 2007), it is described that two of the three erasers containing DEHP have been described as toys and thus been banned. In another memorandum entitled “Erasers containing DINP” (Danish EPA, 22 June 2007), of six erasers contained DINP, five were described to be toys and were thus banned.
The main focus of this opinion will therefore be to evaluate the potential for exposure to DEHP from uses of DEHP-containing erasers by children. The major exposure route to phthalates from the items investigated in the Danish study is by licking and chewing on the items as well as swallowing small pieces of the item. The most relevant items in school supplies are erasers due to their small size, as more frequent biting and licking on bags and cases is considered as unlikely. SCHER agrees with the conclusion that erasers may be the only relevant source for phthalates from the selection of school supplies investigated.
Validation exercises within the EU and CEN have shown that migration of phthalates into artificial saliva of several compositions, at neutral pH, were comparable (Bouma and Schakel, 2002; Earls et al. 2003; CSTEE, 1998). Thus, it is expected that phthalate migration into artificial sweat will be comparable with that into artificial saliva and the data obtained from the migration studies using artificial sweat can therefore be extrapolated to migration into artificial saliva. The experiments using artificial sweat are performed under static conditions at 40°C and the content of phthalates in the products used for these experiments is not known. Therefore, no conclusions are possible.
2.2 What are the weaknesses of the Danish study?
The SCHER opinion states:
3.2. General conclusions based on the reviewed study report
In general, the study design and the report contain several weaknesses, which hamper its evaluation and the ability to come to conclusions based on the results. The report is confusing as not all details required for an evaluation are included; some information is given in the section on exposure, some in the section on risk assessment. Furthermore, only limited and sometimes diverging information on quality assurance of the analyses is provided.
However, SCHER agrees that the presence of phthalates in school supplies other than erasers is of low concern since dermal contact may be the only reasonable exposure pathways for children. Exposure from this pathway is expected to be very limited due to limited skin contact and inefficient dermal uptake.
Erasers may be of concern when they contain phthalates. However, based on the report, a science-based risk assessment of this potential exposure cannot be performed due to the following deficiencies in the report:
- The migration of DEHP into artificial saliva (pH 5.0) was only studied from one eraser (DEHP content 44%, w/w) in a 1 g sample cut into small pieces (cubes) with a width of 2-3 mm at 37°C for one hour. This procedure gives a much larger area for migration, and thus results in excessive leaching of the plasticizer. The study authors have calculated a six fold overestimation. The analysis of chemicals migrated into artificial sweat was performed correctly using an extraction technique that only measures dissolved substances. The phthalate data from this investigation are much lower than the DEHP migration from the eraser into artificial saliva.
- Small pieces of the eraser material suspended in the artificial saliva at the end of the migration experiment were not removed before extraction, which may further overestimate DEHP migration.
- It is not clear whether the extraction was performed under static or under dynamic (= shaking) conditions since, in a memorandum called “Erasers containing DINP” (Danish EPA, 22 June 2007), the same experiment is described as “the sample was shaken with the artificial saliva”.
- The uncertainty of the determinations has been reported to be 50% - which is considered to be indicative of a low quality of the chemical analyses, especially as stable isotope-labelled DEHP was used as an internal standard.
- To obtain information on a potential phthalate release from swallowed eraser particles, the migration of phthalates should be analysed using artificial gastric juice, normally 0.05% HCl.
In summary, SCHER considers that, due to the many weaknesses in this study and its reporting, firm conclusions on release of DEHP and DINP from the erasers as a basis for an assessment of potential health risk cannot be made.
However, SCHER will use some of the data presented in the Danish EPA report for a screening risk assessment of the exposures to phthalates from erasers to indicate the magnitude of a possible problem and information needs.