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DEHP  [Bis(2-ethylhexl) phthalate, di(2-ethylhexyl) phthalate, or dioctyl phthalate] is commonly used as a plasticizer in polyvinyl chloride (PVC) polymers to make them flexible. The use of DEHP has been so widespread that phthalates are now ubiquitous in the environment.

California Proposition 65 currently establishes a no significant risk level of 80 ug/day, low compared to the percent levels used in plastics and our possible exposure. Several research groups believe that DEHP acts as a hormone disruptor.  An NTP panel found that out of several phthalate esters, only DEHP is a significant concern as a reproductive toxin.

Common uses of flexible PVC tubing and DEHP that are currently under attack are in power cords and medical devices (intravenous sets and delivery tubes) .

DEHP, bis(2-ethylhexyl) phthalate, or dioctyl phthalate

bis(2-ethylhexl) phthalate, DEHP, or dioctyl phthalate (DOP) is a commonly used plasticizer in vinyl plastics

 

C&EN March 3, 2003

C&EN Nov 14, 2005

FDA Safety Assessment
 for Medical Devices


Testing for DEHP and other Phthalates

Phthalates can be determined by gas chromatography (GC, EPA Methods 606 and 8060) or gas chromatography -mass spectrometry (GCMS, EPA Methods 525 and 8270). GCMS is the preferred technique due to the added specificity of the mass spectrometer detector and the potential for interferences in complex samples. The detection limit in solution is less than 1 ug/mL. With common extraction and concentration techniques, GC and 

 

GCMS are capable of detecting ppb levels of phthalates. 

Factors which need to be taken into account when analyzing for DEHP are that (1) it may be one of several phthalate esters used in the plasticizer and (2) phthalate esters hydrolyze in water to phthalic acid (1,2-benzenedicarboxylic acid). Some commercial plasticizers use complex mixtures of phthalate esters of which DEHP is only a minor part and may be difficult to resolve from other esters. 

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DEHP using GCMS


Interlaboratory Study

In February 2002, WCAS participated in an international interlaboratory study to measure various phthalates in three types of PVC.  The study was conducted by the Institute for Interlaboratory Studies (IIS), and 20 laboratories participated.  WCAS was the only lab in the US to participate.  The GCMS technique described above was used to test for 11 different phthalate esters.  The samples included a transparent PVC with 17% phthalate, a yellow toy containing 0.7%, and an orange bulk PVC containing about 1%.  The results from the study can be viewed at IIS web site.

The results for DEHP are summarized below.  The study included 10 other phthalate esters as well as total phthalates.  Our results showed no false positives or false negatives, and all results were within one standard deviation of the mean.

DEHP Wt%
Sample

Study
Mean SD

WCAS
Results
210 16.8 1 17.1
211 0.0104 0.007 0.0054
212 0.28 0.14 0.29

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