Di(2-ethylhexyl)phthalate, also known as bis(2-ethylhexyl)phthalate and commonly referred to as DEHP, is a liquid widely used to make plastics more flexible. Plastics may contain from 1 to 40% DEHP by weight and are widely used in consumer products such as imitation leather, rainwear, footwear, upholstery, flooring, tablecloths, shower curtains, food packaging materials, and children's toys. Plastics containing DEHP are also used for tubing and containers for blood transfusions and blood products. DEHP is also used as a hydraulic fluid and as a dielectric fluid (a nonconductor of electric current) for use in electrical capacitors.
Structural diagram: National Institutes of Health
Fate & Transport
DEHP sticks to soil and moves very slowly. After disposal of products in a landfill, the DEHP will slowly leach from the plastic product and may reach the groundwater. However, the low solubility of DEHP in water limits the amounts that will enter the environment by this route.
About 300 million pounds of DEHP are used each year to manufacture plastic products for commercial, medical, and consumer use. Low-level exposures to DEHP from the air or drinking water occur whenever these products are used. Plasticizers such as DEHP do not become a permanent part of the plastic matrix during the manufacturing process. Thus, under certain use or disposal conditions, DEHP can migrate from plastic products into the environment. As a result, DEHP is widely distributed in the environment, and exposure can occur via air, water, and food. DEHP sticks to soil and moves very slowly, however. Therefore, most exposures to DEHP are at very low levels, and exposures via air and water are expected to be minimal.
A potential exists for DEHP contamination of food during processing, handling, transportation, and packaging. DEHP is found in animal products used for human consumption. DEHP dissolves more easily in oil or fatty foods, and the highest levels have been detected in milk and cheese. The U.S. Food and Drug Administration (FDA) currently allows the use of DEHP plasticized containers or wrappings only for foods that primarily contain water; therefore, properly packaged foods are unlikely to become contaminated. The FDA ruling, however, does not preclude the possible misuse of DEHP plasticized containers or wrappings by the consumer.
Acute exposures to relatively high levels (compared to DEHP levels commonly found in food or drinking water) of DEHP can occur when DEHP migrates from the plastics used in medical apparatus (such as storage bags and tubing) used for blood transfusions or kidney dialysis. Patients exposed to DEHP through medical procedures such as dialysis may conceivably be at risk from its toxic effects, but confirmatory studies are necessary to show this relationship.
Some exposure may occur from the evaporation of DEHP from plasticized products during their use. The level of such exposures will depend on the thickness of the plastic item, the temperature, and the specific nature of the product. Therefore, it is difficult to estimate the level of this kind of exposure. However, because the vapor pressure of DEHP is extremely low, and essentially no evaporation occurs at normal room temperature, inhalation exposure is expected to be negligible.
Most discarded plasticized products are disposed of either by incineration or by dumping in a landfill. Incineration is not likely to result in significant exposures to DEHP. Exposure from water may also occur if DEHP migrates from some kinds of flexible plastic tubing used to carry drinking water. Again, because DEHP is not very soluble in water, the exposure level may be low but could continue for a long period of time.
Estimation of human exposure to DEHP is very complex because of the wide range of items containing DEHP and the large number of variables influencing how much of the DEHP content of an item would reach an exposed individual and be absorbed into the body.
There are several potential sources of exposure to DEHP. Humans are primarily exposed through foods that come into contact with packaging materials containing DEHP. Once DEHP gets into the gastrointestinal tract, it is quickly absorbed and gets into the blood and is rapidly metabolized. Humans may also receive higher exposures during blood transfusions and kidney dialysis because of the movement of DEHP into blood from plastic bags and tubing.
It is also possible for children to ingest DEHP by accidentally eating contaminated soil, or for DEHP to leach into water sources, but this would have to continue at very high levels for months or years before any effect might occur.
There are essentially no studies on the health effects of DEHP in humans. However, the U.S. Department of Health and Human Services has determined that DEHP may reasonably be anticipated to be a carcinogen. DEHP causes cancer in rats and mice. It is also known to produce liver damage and male reproductive system damage, affect reproduction, and produce birth defects in laboratory animals. Because none of these effects have been documented in humans, it is difficult to estimate the kinds of health effects and exposure levels that may actually affect humans. However, it is prudent to regard the animal data as indicating some degree of concern for harmful human effects until more research can be done.
DEHP has been shown to cause liver tumors in both rats and mice receiving DEHP in their diet throughout their entire life span. Based on the results of these cancer studies, the National Toxicology Program has classified DEHP as a substance that may reasonably be anticipated to be a carcinogen.
Information excerpted from:
Toxicological Profile for Di(2-ethylhexyl)phthalate April 1989