3. To what extent can children be exposed to phthalates through erasers?
Exposure of children to phthalates from erasers is from chewing or licking.
- how much phthalates from the eraser passes into the saliva;
- how long the child sucks or chews on the eraser and in what way;
- how much of the eraser is swallowed as small particles;
- to what extent the phthalates from these particles passes into gastric juice;
- to what extent phthalates are absorbed in the body from saliva and the gastrointestinal tract.
According to the Danish study a child is exposed to 120 µg of DEHP per square cm of eraser which is in contact with its saliva for an hour (120 µg/cm2/h), but this is likely to be a six-fold overestimate. This rate of transfer from eraser to saliva is comparable to the highest DEHP values measured in a US study and ten times higher than the results for DINP releases in two European studies. Therefore, in this risk assessment, the figure of 120 µg/cm2/h is considered a worst-case scenario. It is also assumed that 100% of the phthalate in the saliva or in swallowed particles passes into the body.
The Danish report also assumed that a child sucks on a piece of eraser for one hour per day, which the SCHER considered a reasonable worst case given that most children hardly ever put an eraser into their mouths.
In the Danish report, the exposure through ingestion of small solid particles after chewing was calculated for 8, 50 and 100 mg of particles per day. However, practical experiences show that such bitten-off pieces of eraser are not easily swallowed, and the SCHER considers that 8 mg of particles per day is the only realistic value.
Another big unknown, which represents the largest uncertainty factor in this assessment, is how frequently children bite and swallow bits of erasers.
With these assumptions, the total exposure to DEHP from 1 cm2 of an eraser containing 44% DEHP may be 0.1 mg or up to 4 mg per child per day depending on whether the child merely licks the eraser or if particles are bitten off and swallowed. When combining all worst-case scenarios, exposure to DEHP from chewing erasers could reach up to 4.1 mg per child per day, which is equivalent to 0.2 mg/kg body weight per day for a 6 year old child who weighs 20 kg. This is four times the tolerable daily intake (TDI) of 0.05 mg/kg body weight per day. The margin of safety compared to the lowest level of DEHP at which no adverse effect were observed in animals (NOAEL) is 25, when the generally accepted margin of safety is 100 times.
However, licking on erasers and swallowing bits of them is a short-lived habit and children are unlikely to swallow large amounts of eraser in this way. The exposure time is short and phthalates are rapidly transformed and eliminated from the body. Comparing such worst case short term exposures with the TDI, which is meant for regular, lifetime exposures, is not really appropriate here. Moreover, the assessment of exposure by swallowing particles relies on a single exploratory experiment, which needs to be repeated to confirm the findings. Only very few children in the groups where DEHP intake was determined from urine samples (biomonitoring) exceeded the TDI. More...