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?
A number of items, including erasers, were analysed for chemical content.
Source: Allen Pope
The Danish Environmental Protection Agency (Danish EPA) tested school supplies for the presence of phthalates as part of a wider programme that investigates exposure and possible risk of chemicals in consumer products and articles. After a market survey, a number of school bags, toy bags, pencil cases and erasers were bought and analysed.
A chemical analysis was carried out to detect the presence of various substances in these articles. More specifically:
- chlorine content was investigated in order to identify the products containing PVC (polyvinyl chloride).
- some product samples were tested to see what types of polymer they contained.
- X-Ray analysis was used to assess the presence of chlorine, bromine, tin, sulphur and nickel.
- the potential release of volatile organic compounds (VOCs) was evaluated.
- some product samples were analysed for specific metals, colouring agents, antioxidants and perfluorinated compounds
- to what extent chemicals pass from the sample to artificial sweat and saliva was studied.
Of all products, 46 including 26 erasers, were tested in more detail to find out how much they contained of each chemical. Nine of the erasers contained phthalates. Three of them contained 22-44% of DEHP and six contained 32-70% DINP. The study also found DIBP and DBP in some of the products, but did not measure the total content of these phthalates. It studied the extent to which chemicals from 14 products pass into artificial sweat and saliva, but none of these products were erasers. The results showed that DIBP and DEHP were released by 11 and 5 products respectively.
The major exposure route to phthalates from the products investigated in the Danish study is by licking, chewing and swallowing small pieces of the item. The SCHER agrees with the conclusion that erasers may be the only relevant source for phthalates from the selection of school supplies investigated, and the other products tested do not present a health risk for children. The only potential source of concern in the study was exposure to DEHP from erasers through sucking and chewing, and this is the main focus of the present opinion. More...
2.2 What are the weaknesses of the Danish study?
In general, the way the Danish study was designed and the report derived from this study contain several weaknesses, which makes it difficult to come to conclusions based on the results. The report from the Danish study is confusing as not all details required for an evaluation are included. Furthermore, the information it gives on quality assurance of the analyses is limited and sometimes contradicting.
The SCHER agrees that the presence of phthalates in school supplies other than erasers is of low concern since contact with the skin – which is limited – may be the only reasonable way for children to be exposed and that only small amounts of phthalate go through the skin. However, erasers that contain phthalates may be of concern because they can leach DEHP and DINP when children put them in their mouths. But it was not possible for the SCHER to make a proper risk assessment of this potential exposure because of deficiencies in the report. Notably:
How much DEHP pass into artificial saliva was only studied from one eraser in a sample that had been cut into small pieces. This gives a much larger surface area of contact between the eraser and the artificial saliva and results in excessive leaching of the plasticizer. It was calculated that the results could be six times higher than the true values. Proper analyses on the release of DEHP into artificial sweat give much lower values and are further evidence that the results of the Danish study are overestimates.
- When the artificial saliva was analysed to measure the amount of DEHP that had leached into it, it still contained small pieces of eraser that had not been removed and this could overestimate DEHP release even more.
- The uncertainty of the results is reported to be 50%, which indicates that the chemical analyses are of poor quality.
- The Danish study should have used artificial gastric juice to measure a potential release of phthalate from swallowed bits of eraser.
In summary, the SCHER considers that due to the many weaknesses in this study and its reporting, the figures given for the amounts of DEHP and DINP leached cannot be used as a basis to assess the potential health risk of phthalates released from erasers. More...