Phthalates in school supplies

4. To what extent are people exposed to phthalates?

The diet, particularly fatty food, is responsible for most of the DEHP exposure in adults.
Source: Steve Woods

The EU-Risk Assessment Reports (RAR) on various phthalates have made a detailed assessment of exposure based on known concentrations in food, the environment and materials, and models that predict what proportion of the substance is taken up by the body. For DNOP, however, no such assessment report is available and information on use patterns, occurrence, and human exposures is lacking.

More recent studies assess human exposures to phthalates by measuring the biological breakdown products in urine, since this method gives more precise estimates. One such study on children in Germany showed that exposure was higher in boys than in girls, and children aged 6-7 years were significantly more exposed than children in the age group 13-14 years.

Overall, our knowledge of how the body takes in phthalates and how it transforms, metabolises and eliminates them is limited. In addition, the extent to which age influences these processes has not been sufficiently evaluated. Still, the average exposure of children is known to be approximately twice that of adults. Different lifestyle factors, eating behaviours, and the ingestion of dust from indoor surfaces may also play a role. A recent study from Germany comparing concentrations in the food and in the urine of 5-8 year old boys indicated that diet was responsible for about 50 % of their exposure to DEHP, so other important sources must exist. For adults, DEHP exposure is mainly due to diet, particularly fatty foods.

While DEHP was the phthalate most commonly used in consumer products in the 1990s, it has since been increasingly replaced by DIDP because of health concerns. Between 1999 and 2004, the proportion of DEHP in total phthalates use decreased from 42% to 22% and the proportions of DINP and DIDP increased from 35% to 58%. The change in use has been reflected in a change in exposure to these two phthalates. A study in Germany on 20-29 year olds showed continuous decrease in DEHP exposure from 1996 until 2003 and a corresponding increase in DINP exposure.

A US study calculated the daily intake of DINP in children of different ages, based on estimates of how long children put products containing DINP into their mouth and of how much would pass into the body. The average estimate was 0.0057 mg/child/day for children aged between 3 and 12 months, but there were very large variations, with 5% of children expected to take in 0.0943 mg/child/day or more. The values for children at 13-26 months were considerably lower with a mean of less than 0.001 mg/child/per day. At present, there is a lack of direct measurements of the breakdown products of DINP or other phthalates in the urine of children that would allow a more precise assessment of exposure.

In conclusion, the exposure data based on urine samples indicate that average exposures are well below the tolerable daily intake (TDI) for DEHP, but it may approach or even exceed the TDI in some highly-exposed groups of population, notably people exposed through medical procedures such as kidney dialysis. For the other phthalates studied, calculated exposures are below the TDIs except for DBP. A significant portion of the population may be exposed to doses of DBP above the TDI and efforts to further reduce exposures are needed. More...

Measured urinary concentrations for different phthalates

Overview of the main phthalates and their applications