Mixed messages on phthalate leaching risks

Dutch consensus group study finds low average risk, some babies could exceed "benchmark" doses

The Dutch consensus study on risks to babies from phthalates contained in soft PVC toys has been leapt upon by all sides in the debate to justify pre-existing positions. The results suggest that average risks are low, but that acceptable doses could be exceeded in extreme cases, leaving future EU policy decisions still firmly in the political domain.

The scientific group had four main goals: to identify "real" migration levels of phthalates from toys to saliva using adult human volunteers; to observe how long real babies chew or suck on toys or other items; on the basis of the first two results to make a new risk assessment, updating the conclusions of an EU scientific committee (ENDS Daily 29 April); and finally to develop a reproducible phthalate migration testing method for future use,

The group based its study of migration on three samples of soft PVC. It looked only at one phthalate compound, DINP, since this "appeared to be the phthalate predominantly used in soft PVC toys". It found migration levels of around 1.4 micrograms per minute (ug/m) for two of the samples and 2.4 ug/m for the third. Data from this last sample were used in the risk assessment. The group concluded that it was "acceptable to use the [observed] release rates...as the best estimate of release rates in young children".

A "child observation" study on how long on average babies chew or suck toys and other items found wide variation within and between age groups. For all age groups, the mean "mouthing" time was 26 minutes. Children aged 3-6 months tended mostly to suck their own fingers, while children between 6 and 12 months spent the most time mouthing toys.

Based on the two preceding studies, the group made exposure and risk assessments. To assess risk, it compared calculated doses with a "tolerable daily intake" of 0.15 milligrams per kilogram bodyweight per day agreed by the EU scientific committee in April. Based on an educated guess that other sources of DINP exposure might amount to 0.05 mg/kg/day, the group provisionally used a dose of 0.1 mg/kg/day from toys as a benchmark of acceptable uptake.

In the exposure assessment, the scientists estimated mean doses for children aged 3-6 months to be 14% of this "acceptable" level. For children aged 6-12 months the figure was 12%. For older children it was much lower. Doses in the top one per cent of the exposure range were 77% and 75% of the benchmark for the two age groups respectively. However, the maximum levels observed were 112% and 204% of the benchmark for the two groups respectively.

Finally, the group developed a reproducible method for testing phthalate migration in laboratories. After encountering a number of technical problems, the scientists developed a method which they say "provides repeatable results and is theoretically the most promising for standardisation between laboratories".

Follow Up:
RIVM tel: +31 30 274 9111. References: Minutes of consensus group meetings are available on the web site of the Dutch health ministry.

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