Phthalates Di(2-ethylhexyl) phthalate (DEHP)
Skalsky & Associates has experience with the use and migration of plasticizers like Di(2-ethylhexyl) phthalate (DEHP). DEHP is a manufactured chemical that is commonly added to plastics to make them flexible. DEHP is often referred to as a secondary plasticizer.
As a secondary plasticizer, DEHP is not chemically bound to the plastic to which it is added, and is it is free to be released into the environment when the plastic is used. In general, the more flexible the product, the more DEHP it contains.
DEHP can be present in plastic products such as wall coverings, tablecloths, floor tiles, furniture upholstery, shower curtains, garden hoses, swimming pool liners, rainwear, baby pants, dolls, some toys, shoes, automobile upholstery and tops, packaging film and sheets, sheathing for wire and cable, medical tubing, and blood storage bags.
DEHP is rapidly broken down in the gut to mono(2-ethylhexyl)phthalate and 2-ethylhexanol. DEHP is lipophilic and tends to accumulate in adipose tissues. DEHP and its derivatives are predominately excreted in the urine and approximately 20–25% of absorbed DEHP is excreted in the feces. Studies indicate that DEHP may also interfere with the male endocrine function and influence male sexual development. Testicular toxicity and developmental toxicity, observed in different animal species and at relatively low dose levels are considered relevant to humans.
DEHP in indoor air is due primarily to volatilization from consumer products and building materials that contain DEHP. In general, concentrations are expected to be higher in the indoor air than in the outdoor ambient air. Some studies have suggested that because of DEHP’s tendency to adsorb to airborne particulates, levels estimated based only on gas-phase measurements might underestimate total air levels. It is suggested that exposure to DEHP from indoor air may increase by a factor of up to three when particulate matter contributions are accounted for.
There are over thirty metabolites of DEHP that have been detected in the human urine. NHANES reported on 4 of the major metabolites of DEHP. Mono-2-ethylhexyl phthalate (MEHP) is formed by the hydrolysis of DEHP in the gastrointestinal tract and then absorbed. The urinary levels of MEHP reported by NHANES are:
- 1999-2000 6-11 years of age GM => 5.19 µg MEHP/g creatinine. 95th % => 41.9 µg MEHP/g creatinine
- 2001-2002 6-11 years of age GM => 5.03 µg MEHP/g creatinine. 95th % => 31.4 µg MEHP/g creatinine
- 2003-2004 6-11 years of age GM => 2.80 µg MEHP/g creatinine. 95th % => 28.7 µg MEHP/g creatinine
- 1999-2000 20-+ years of age GM => 3.03 µg MEHP/g creatinine. 95th % => 17.5 µg MEHP/g creatinine
- 2001-2002 20-+ years of age GM => 3.97 µg MEHP/g creatinine. 95th % => 34.5 µg MEHP/g creatinine
- 2003-2004 20-+ years of age GM => 2.14 µg MEHP/g creatinine. 95th % => 25.6 µg MEHP/g creatinine
Daily exposure of adults in the general population is estimated to range from 1 to 30 μg/kg of body weight (0.001 to 0.03 mg/kg) (NTP 2006). Exposure may be several times as high in infants and toddlers, as a result of non-dietary mouthing behaviors. It is believed that ingestion of household dust accounts for about half of total DEHP intake for infants. The concentration of DEHP in house dust was associated with the use of PVC-based flooring and wall coverings in the homes.
Of concern to the construction industry is the fact that emission rates of DEHP release from vinyl flooring has been characterized and vinyl flooring is now being recognized as a major potential source of DEHP exposure. It is also concerning that investigations have linked phthalates, particularly DEHP, to both allergies and asthma in children. In fact, a direct association between the concentration of DEHP in indoor dust and wheezing among preschool children has been recently reported.
A variety of chemicals have been found to disrupt the endocrine systems of animals in laboratory studies. However, only one chemical, diethylstrilbestrol (DES) has been demonstrated to be an endocrine disruptor in humans. This potent drug, a synthetic estrogen, was prescribed to as many as five million pregnant women to block spontaneous abortion and promote fetal growth.
It was discovered after the children of those women went through puberty that DES affected the development of the reproductive system and caused vaginal cancer. There are some that believe that both BPA and DEHP may be endocrine disruptors. However, for the present, this is more a matter of belief and politics than science.