Playing with plastics: Phthalate transfer from toys to children via sweat

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  • Published: Mar 1, 2012
  • Author: Steve Down
  • Channels: Base Peak
thumbnail image: Playing with plastics: Phthalate transfer from toys to children via sweat

Toys and phthalates

The role of sweat in the migration of one toxic phthalate plasticiser from toys to children has been estimated by Turkish scientists using GC/MS, in the first study of its type.

Phthalate esters are a common type of plasticiser that are added to plastic products to make them softer and more flexible. They are also added to myriads of other consumer products like personal care products, plastic wrapping, detergents, lubricants and building materials. Phthalates are ubiquitous chemicals in the manufacturing process and they have inveigled their way into the environment and into all of our bodies.

Everyone has traces of phthalates in them, which inevitably leads us to the health question. Are phthalates safe? Well, the jury is still out in this case because the evidence is inconclusive. Some phthalates have been declared possible carcinogens and there have been links to reproductive defects and endocrine disruption, but no causal links have yet been established.

The doubts associated with phthalates have led to special legislation in many countries to protect children, who are more vulnerable because they will place objects in their mouths. Phthalates are not chemically bound to the plastics, so can be released easily by licking, as well as by touch.

In the EU, certain low-molecular-weight phthalates are banned from all toys and childcare articles. These include the dibutyl, butylbenzyl and di(2-ethylhexyl) esters of phthalic acid. Some higher-molecular-weight phthalates which are of lesser concern are limited to articles which cannot be placed in the mouth. The US took a stronger stance in 2008, banning all phthalates from toys intended for the under-12s.

Apart from exposure by ingestion and/or direct dermal contact, one potential area of influence has been overlooked to date, according to two Turkish scientists. Elif Tumay Ozer and Seref Gucer from Uludag University, Bursa, thought that sweat might facilitate phthalate transfer from toys onto the skin.

They decided to investigate the possibility using artificial sweat and focused their attention on one particular phthalate, di(2-ethylhexyl) phthalate (DEHP), which is one of the more popular plasticisers used in industry.

 

A sweaty approach to phthalate transfer

There is no "universal" artificial sweat formula. The researchers used an aqueous solution of sodium chloride, urea, and lactic acid, which is similar to others that have been concocted for different studies.

They devised an extraction procedure using activated carbon to remove DEHP from the sweat, which was optimised using a central composite design process. The most important factors were the pH, the amount of activated carbon and the adsorption time.

The highest recovery of DEHP spiked into the artificial sweat was achieved at pH 2.2, with a sorption efficiency of 92%. The phthalate was extracted from the activated carbon with chloroform containing benzyl benzoate as an internal standard for GC/MS measurement. Following electron ionisation, four ions at m/z 113, 149, 167 and 270 were adopted for selected ion monitoring mode. The detection limit was 13.8 µg/L, which is lower than reported for some mass spectrometric determinations after ultrasonic and solid-phase extraction.

The method was used to study the migration of DEHP from three plastic toys into artificial sweat. Small sections were cut out with a punch and mixed with the sweat solution and DEHP was extracted with the optimised activated carbon procedure.

The amounts of DEHP released from two of the toys were 65 and 130 µg which corresponded to release rates of 16.6 and 33.1 µg/10 cm2/h, respectively. These release values are higher than those previously measured by the same two researchers for artificial saliva but that could be due to the presence of lactic acid and urea in the sweat, which increase the solubility of DEHP.

For intact toys, the release rates will depend on their physical characteristics like roughness, thickness and the type of surface coating. The new method will allow the transfer of DEHP from toys to sweat to be estimated and incorporated into risk assessments for children, supplementing direct dermal absorption and oral ingestion as routes of exposure.

Related Links

Polymer Testing 2012, 31, 474-480: "Determination of di(2-ethylhexyl) phthalate migration from toys into artificial sweat by gas chromatography mass spectrometry after activated carbon enrichment"

Article by Steve Down

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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