Phthalate in Schulsachen

3. To what extent can children be exposed to phthalates through erasers?

The SCHER opinion states:

Exposure of children to phthalates from erasers is from chewing or licking.
Source: GreenFacts

3.3. Possible contribution of erasers to phthalate exposures in children

The internal exposure of a child to DEHP and DINP from erasers by licking and chewing is dependent on the following factors:

1. the migration of the substance to saliva
2. the time the user is sucking/chewing on the eraser and how it is done
3. the amount of particles swallowed from the eraser
4. the migration of the substance from the particles into gastric juice
5. the bioavailability of the substance from saliva and the gastrointestinal tract

For a screening assessment, the data for the Danish EPA study are used to represent a worst case situation acknowledging that this may be an overestimation regarding the release from sucking and licking. In the Danish study, 0.1% of DEHP migrated to artificial saliva within one hour from an eraser containing 44% of DEHP. As this was obtained after cutting the eraser into smaller pieces the authors estimated it to give a 6-fold overestimation. As an example, an eraser measuring 11*18*40 mm has a surface of 8 cm² and a weight of 13 g. The DEHP migration measured in the Danish study then corresponds to a release of more than 120 µg/cm²/h. This is almost ten times higher than what was found for DINP migration in two European chewing studies (Könemann, 1998; Steiner et al., 1998), but comparable to the highest values found in a US study (US CPSC, 1998). A worst-case release of DEHP may thus indeed be 120 µg/cm²/h.

A more difficult parameter to estimate is the suction time. Most children will never put an eraser into their mouth, and there are probably some that do it more frequently, and a few may do it over longer time periods. In the Danish report, it is assumed that a child sucks on a piece of eraser (1 gram) for one hour per day. SCHER has no other information and will use this assumption as a reasonably worst case.

Bioavailability of phthalates from saliva or swallowed particles is assumed as 100 %, but the amount of small eraser particles swallowed after chewing is very difficult to estimate. However, practical experience shows that small particles bitten off an eraser are sharp and not easily swallowed. In the Danish report, the exposure via swallowed particles was calculated for 8, 50 and 100 mg of particles per day. SCHER considers higher particle consumptions as unrealistic and will concentrate on the lowest level (8 mg of particles) in its exposure assessment. In addition, it is not known how frequently biting and swallowing occurs in children. This represents the largest uncertainty factor in this assessment.

With these assumptions, the total exposure to DEHP from 1 cm² of an eraser containing 44% DEHP may be 0.1 mg/child from sucking and licking. Biting off pieces and swallowing these particles may result in an intake of up to 4 mg DEHP/child. It is obvious that the swallowed fraction may be the dominant exposure pathway, but the uncertainty regarding the relevance of the pathway for overall DEHP-exposure is high. Combining all these worst-case scenarios it results in an exposure of 4.1 mg/child or 0.2 mg/kg for a 6 years old child of 20 kg of weight. This exposure is 4-fold above the EFSA TDI of 0.05 mg/kg/day for DEHP and with a MOE (margin of exposure) of 25 to the NOAEL for DEHP of 4.8 mg/kg bw/day identified by CSTEE (2004), derived with a major contribution from swallowed particles. Uptake of DEHP by licking only, even when using a conservative assessment, will not exceed the afore-mentioned highly conservative EFSA TDI for DEHP.

However, swallowing of a larger number of particles from an eraser containing DEHP likely represents an infrequent event due the nature of the particles (see above) and the fact that only a very small number of children in the groups where DEHP intake was assessed by biomonitoring (see below) exceeded the TDI. In addition, licking on erasers and swallowing particles bitten off an eraser represents a short-time habit of children resp. a one-time event as outlined in the report. Therefore, due to the short exposure time, it is inappropriate to use the TDI (derived for lifetime exposures) from a chronic study for risk assessment due to the rapid biotransformation and excretion of phthalates. Moreover, the assessment of exposure by swallowing particles relies on a single exploratory experiment, which needs to be repeated to confirm the findings.

Source & ©: SCHER   Opinion on phthalates in school supplies (2008),
3. Opinion, 3.3. Possible contribution of erasers to phthalate exposures in children, p. 8 – 9