Plasticizers diethylhexyl phthalate

The plasticizer diethylhexyl phthalate induces malformations by decreasing fetal testosterone synthesis during sexual differentiation in the male rat. Toxicol Sci 58 339-349... 

The National Toxicology Program asserts that phthalate plasticizers [diethylhexyl phthalate (DEHP), used in vinyl] are a health hazard and should be phased out of medical products. The major use of DEHP is in the production of PVC and vinyl chloride resins, in which it is added to plastics to make them flexible. 

The rapid movement in the global phthalates market away from using plasticisers 2-ethylhexanol (2-EH) and diethylhexyl phthalate (DEHP) in favour of alternative products was underscored recently when BASF revealed plans to close its 2-EH and DEHP plants in Germany. The restructuring in Europe will have no effect on BASF s plasticiser portfolio in Nafta and Asia, however, where the company will continue to offer 2-EH and DEHP. About 70% of the plasticiser maiket volume is phthalates, and plasticisers make up about 60% of the plastic additives maiket. PVC accounts for 80-90% of global plasticiser consumption. In October 2003, California added DEHP to the state s list of more than 750 chemicals known to cause birth defects or reproductive harm. Previous studies had shown that the chemical can leach from plastic bags that contain intravenous fluids, blood, tube feedings or other medical treatment, and thereby enter the bodies of patients. 

Polyvinyl chloride can be shaped into clear, soft flexible tubing and sheets with the aid of using plasticizers such as diethylhexyl phthalate (DEHP). Polyvinyl chloride resins are used for children s toys, automobile seat covers, and for catheters used for intravenous transfusion of blood and nutrients in hospitals and homes. When DEHP was suspected of leaching out of the products, and of being a carcinogen, substitutions were developed with polyvinylacetate and polyethylene. However, these substitutes are not yet totally satisfactory, as they cannot be steam sterilized, and they are not as clear and flexible as PVC. 

Studies conducted by different authors on the release of chemical substances from medical devices, mainly those used for infusing solutions, show that these are potential sources of contamination for pharmaceutical formulations. One of the most studied is diethylhexyl phthalate, the same plasticizer found in PVC infusion bags to give flexibility. The same concerns about the use of PVC bags for the storage of lipids or lipophilic formulations are valid for tubing. 

Various chemicals, such as the fibrate (e.g., clofibrate, bezafibrate, and ciprofibrate) and other lipid-lowering drugs (e.g., Wy-14643) and phthalate plasticizers (e.g., diethylhexyl phthalate), bind to and activate PPARa and are also hepa to carcinogenic in rodents. However, different compounds bind with different affinities, from strong (e.g., Wy-14643) to weak (e.g., phthalates). Thus, it is believed that peroxisomal proliferators act via the receptor (PPARa) to cause some of the effects seen. 

Figure 13. Mechanical damping of PVC plasticized with diethylhexyl phthalate (30)...

Paclitaxel injection containing alcohol and polyethoxylated castor oil may deplete diethylhexyl phthalate from plastic sets.227... 

Rock and co-workers (1988) reported the interaction of diethylhexyl phthalate with blood during storage in PVC plastic containers. The plasticizer is leached into the plasma and converted to mono(2-ethyIhexyl) phthalate by a plasma enzyme. At a level of >125 mg/mL in the blood mono(2-ethyl-hexyl) phthalate produced a 50% decrease in heart rate and blood pressure in rats. 

Isodecyl octyl phthalate n. C10H21OOCC6 H4COOC8H17. A primary plasticizer for vinyls, cellulose nitrate, polystyrene, and ethyl cellulose. In vinyls, it performs better than diethylhexyl phthalate (DOP). 

Although there are about 100 phthalates that have been employed as plasticizers, around 14-15 phthalates account for over 90% of commercial phthalate production. The most commonly used phthalate is diethylhexyl phthalate (DEHP), which is often called dioctyl phthalate (DOP). Other plasticizers used are butyl benzyl phthalate (BBP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), methyl-, ethyl-... 

As just mentioned, making soft PVC from rigid PVC is a well-known example of plasticization. The efficiency of the plasticizer can be easily characterized by TMA simply by measuring Tg. Adding a plasticizer, such as diethylhexyl phthalate with Tg—90 °C, to PVC decreases Tg from -90 °C (Bair and Warren 1981) to about -20 °C at a 60% plasticizer concentration (CeccorulU et al. 1983 Gedde 2001). 

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