Di(2-ethylhexyl) phthalate, known as DEHP, is a chemical widely used as a plasticizer. It makes rigid plastics, particularly polyvinyl chloride (PVC), soft and flexible. This property makes DEHP an additive in many consumer and industrial products, such as vinyl flooring, food packaging, and some children’s toys. Its widespread presence contributes to potential human exposure.
Environmental Absorption Pathways
The general population primarily encounters DEHP through everyday environmental pathways, with ingestion being the most common route. DEHP can leach from plastic packaging and containers into food, especially high-fat items like oils, cheeses, and meats, due to its lipophilic nature. Contamination also occurs from plastic tubing and equipment used in food processing.
Inhalation is another pathway for DEHP absorption, particularly indoors. DEHP can volatilize from products like vinyl flooring, wallpapers, and upholstered furniture, then settle into household dust. People can inhale this contaminated dust, leading to exposure. Indoor dust is a significant reservoir for DEHP particles.
Absorption through the skin, or dermal contact, is possible but generally less substantial than ingestion or inhalation. This can occur when handling soft plastic items like toys or certain personal care products. The extent of dermal absorption depends on factors such as contact duration and product formulation.
Absorption Through Medical Procedures
Exposure to DEHP can be significantly higher and more direct in medical settings. Many medical devices are made from soft PVC containing DEHP for flexibility and durability. These include intravenous (IV) bags and tubing, blood transfusion bags, catheters, and tubes for dialysis or enteral nutrition.
During medical procedures, DEHP can leach directly from these plastic components into solutions that contact them, such as saline, medications, or blood products. This allows direct introduction of DEHP into the bloodstream. For instance, blood storage in PVC bags can lead to DEHP leaching, which directly enters the patient’s circulatory system during transfusions.
Direct intravenous exposure is a particular concern for vulnerable patient populations requiring extensive or long-term medical interventions. Premature infants in neonatal intensive care units, patients undergoing chronic hemodialysis, or individuals receiving prolonged parenteral nutrition can experience higher cumulative DEHP exposure. These groups often have immature or compromised detoxification systems, potentially increasing their susceptibility.
Metabolism and Elimination from the Body
Once DEHP enters the body, it undergoes rapid breakdown through metabolic processes. Enzymes, primarily esterases, quickly convert DEHP into other compounds, with mono-2-ethylhexyl phthalate (MEHP) being the most prominent metabolite. This initial metabolism typically occurs in the gut and liver.
Further metabolism of MEHP can occur, leading to secondary metabolites through oxidation reactions. These metabolites, rather than the parent DEHP compound, are commonly measured in urine samples to assess exposure levels. Detecting these breakdown products indicates DEHP has been absorbed and processed.
The resulting metabolites, including MEHP, are generally more water-soluble than the parent DEHP molecule. This increased water solubility facilitates their excretion. These compounds are relatively quickly eliminated, primarily through the kidneys via urine, often within 24 to 48 hours after exposure.