Bis(2-ethylhexyl) phthalate

Bis(2-ethylhexyl)phthalate (also BEHP, di-2-ethyl hexyl phthalate, DEHP, or dioctyl phthalate, DOP) is a phthalate, a branched-chain 2-ethylhexanol diester of phthalic acid. At normal temperature, it is a liquid with the viscosity similar to vegetable oil. It is soluble in oil, saliva, plasma, but not in water. It possesses good plasticizing efficiency, fusion rate and viscosity.

Use
Due to its low cost, DEHP is widely used as a plasticizer in manufacturing of PVC. Plastics may contain 1% to 40% of DEHP. It is also used as a hydraulic fluid and as a dielectric fluid in capacitors. DEHP also finds use as a solvent in lightsticks.

Environmental exposure
DEHP is slowly released into the air from finished plastic, posing health risks (see outgassing). It can be absorbed from food and water. Higher levels have been found in milk and cheese. It can also leach into a liquid that comes in contact with the plastic; it extracts faster into nonpolar solvents (eg. oils and fats in foods packed in PVC). Food and Drug Administration (FDA) therefore permits use of DEHP-containing packaging only for foods that primarily contain water.

In soil, DEHP contamination moves very slowly. It has low water solubility, therefore leaching from disposed plastics in landfills is generally slow.

The EPA limit for DEHP in drinking water is 6 ppb. OSHA limit for occupational exposure is 5 mg/m3 of air.

Use in Medical Devices
DEHP has been used as a plasticiser in medical devices such as intravenous tubing and bags, catheters, nasogastric tubes, dialysis bags and tubing, and blood bags and transfusion tubing, and air tubes. DEHP leaches out into the fluid or air and is transported into the patient. Certain populations seem to be particularly at risk for DEHP exposure, namely newborns in intensive care nursery settings, hemophiliacs, and kidney dialysis patients.

Metabolism
The metabolism of DEHP depends on several factors, including age, and route of absorption. Oral DEHP is preferentially hydrolyzed to MEHP (mono-ethylhexyl phthalate).

Toxicity
While DEHP has a low lethal toxicity, it affects certain organs at low concentration, specifically the reproductive organs (testis and ovary), lungs, kidney, and liver. Studies show that it crosses the placenta and is embryotoxic. DEHP can also be found in breast milk. DEHP does not absorb easily through skin, therefore contact with DEHP-containing products is not likely to be harmful.

DEHP is a peroxisome inducer and as such can lead to liver neoplasm in rodents, however there appear to be no data to link it to cancer in humans directly. DEHP in small amounts commonly present in environment is not considered harmful.

Risk Reduction and alternatives
The American Academy of Pediatrics has advocated not to use medical devices that can leach DEHP into patients and, instead, to resort to DEHP-free alternatives. A number of hospitals have taken a lead to reduce or eliminate DEHP containing medical devices.

However, in September 2002 the European Union's Scientific Committee on Medicinal Products and Medical Devices published an Opinion on the use of di(2-ethylhexyl) phthalate (DEHP) in medical devices saying that it can make no recommendations to limit its use, even for the most highly exposed patients.

A further review is being undertaken by the EU Scientifc Committee on Emerging and Newly Identified Health Risks (SCENIHR)which will give an Opinion in January 2007.

The European Commission has banned the use of DEHP and some other phthalates in PVC toys.

DEHP is not registered or has been deregistered for use in many (maybe most?) countries of the world.