Plasticizers in blood--real or artifactual?

During our recent work on the identification of drugs involved in overdose cases (1, 2), we have had occasion to investigate the constituents found in blood, urine, and gastric juices by combined GC-mass spectrometry. In a surprisingly large number of cases, we have observed, in addition to any drugs present, one or more peaks corresponding to phthalate esters (PAEs). Most commonly these were di-n-butyl phthalate (DBP) and di-2-ethylhexyl phthalate (DEHP), but occasionally di-2-ethylhexyl adipate and butyl cellosolve phosphate were also present. Often they were present at remarkably high levels, e.g., 200 mg/100 ml in blood. In view of the many possible sources of these plasticizers in the hospital and laboratory environment, we deemed it advisable to study in more detail blood samples from normal individuals, taking special care to prevent the introduction of such compounds from outside sources during sample workup.