Phthalates, or phthalate esters, are esters of phthalic acid and are mainly used as plasticizers (substances added to plastics to increase their flexibility, transparency, durability and longevity). They are primarily used to soften polyvinyl chloride. Phthalates are being phased out of many products in the United States and European Union over health concerns.
Phthalates are used in a large variety of products, from enteric coatings of pharmaceutical pills and nutritional supplements to viscosity control agents, gelling agents, film formers, stabilizers, dispersants, lubricants, binders, emulsifying agents, and suspending agents. End applications include adhesives and glues, agricultural adjuvants, building materials, personal care products, medical devices, detergents and surfactants, packaging, children's toys, modelling clay, waxes, paints, printing inks and coatings, pharmaceuticals, food products and textiles. Phthalates are also frequently used in soft plastic fishing lures, caulk, paint pigments, and sex toys made of so-called "jelly rubber." Phthalates are used in a variety of household applications such as shower curtains, vinyl upholstery, adhesives, floor tiles, food containers and wrappers, and cleaning materials. Personal care items containing phthalates include perfume, eye shadow, moisturizer, nail polish, liquid soap, and hair spray.[1] They are also found in modern electronics and medical applications such as catheters and blood transfusion devices. The most widely-used phthalates are the di-2-ethyl hexyl phthalate (DEHP), the diisodecyl phthalate (DIDP) and the diisononyl phthalate (DINP). DEHP is the dominant plasticizer used in PVC, due to its low cost. Benzylbutylphthalate (BBzP) is used in the manufacture of foamed PVC, which is mostly used as a flooring material. Phthalates with small R and R' groups are used as solvents in perfumes and pesticides.
As of 2004, manufacturers produced about 363 thousand metric tonnes (800 million pounds or 400 000 short tons) of phthalates each year. By weight, they contribute 10-60% of plastic products.[1]
Phthalates are easily released into the environment because there is no covalent bond between the phthalates and plastics in which they are mixed. As plastics age and break down, the release of phthalates accelerates. Phthalates in the environment are subject to biodegredation, photodegredation, and anaerobic degredation therefore they do not generally persist in the outdoor environment. Outdoor air concentrations are higher in urban and suburban areas than in rural and remote areas.[1]
Indoor air concentrations are generally higher than outdoor air concentrations due to the nature of the sources. Because of their volatility, DEP and DMP are present in higher concentrations in air in comparison with the heavier and less volatile DEHP. Higher air temperatures result in higher concentrations of phthalates in the air. PVC flooring leads to higher concentrations of BBP and DEHP which are more prevalent in dust.[1]
People are commonly exposed to phthalates, and the majority of Americans tested by the Centers for Disease Control and Prevention have metabolites of multiple phthalates in their urine. Because phthalate plasticizers are not chemically bound to PVC, they can easily leach and evaporate into food or the atmosphere. Phthalate exposure can be through direct use or indirectly through leaching and general environmental contamination. Diet is believed to be the main source of DEHP and other phthalates in the general population. Fatty foods such as milk, butter, and meats are a major source. Low molecular weight phthalates such as DEP, DBP, BBzP may be dermally absorbed. Inhalational exposure is also significant with the more volatile phthalates.[2]
In a 2008 Bulgarian study, higher dust concentrations of DEHP were found in homes of children with asthma and allergies, compared with healthy children's homes.[3] The author of the study stated, "The concentration of DEHP was found to be significantly associated with wheezing in the last 12 months as reported by the parents."[3] Phthalates were found in almost every sampled home in Bulgaria. The same study found that DEHP, BBzP, and DnOP were in significantly higher concentrations in dust samples collected in homes where polishing agents were used. Data on flooring materials was collected, but there was not a significant difference in concentrations between homes where no polish was used that have balatum (PVC or linoleum) flooring verses homes with wood. High frequency of dusting did decrease the concentration.[3]
Children's exposure to phthalates generally is greater than adults. In a 1990's Canadian study that modelled ambient exposures, it was estimated that daily exposure to DEHP was "9mcg/kg bodyweight/day in infants, 19 mcg/kg bodyweight/day in toddlers, 14 mcg/kg bodyweight/day in children, and 6 mcg/kg bodyweight/day in adults.[2] Infants and toddlers are at the greatest risk of exposure due to their mouthing behavior. Body care products containing phthalates are a source of exposure for infants. The authors of a 2008 study "observed that reported use of infant lotion, infant powder, and infant shampoo were associated with increased infant urine concentrations of [phthalate metabolites], and this association is strongest in younger infants. These findings suggest that dermal exposures may contribute significantly to phthalate body burden in this population." Though they did not examine health outcomes, they noted that "Young infants are more vulnerable to the potential adverse effects of phthalates given their increased dosage per unit body surface area, metabolic capabilities, and developing endocrine and reproductive systems."[4]
In 2008, the Danish Environmental Protection Agency (EPA) found a variety of phthalates in erasers and warned of health risks when children regularly suck and chew on them. However, the European Commission Scientific Committee on Health and Environmental Risks (SCHER) considers that, even in the case when children bite off pieces from erasers and swallow them, it is unlikely that this exposure leads to health consequences.[5]
Phthalates are also found in medications, where they are used as inactive ingredients in producing enteric coatings. It's not known how many medications are made using phthalates, but some include omeprazole, didanosine, mesalamine, and theophylline. A recent study found that urinary concentrations of monobutyl phthalate, the DBP metabolite, of mesalamine users was 50 times higher than the mean of nonusers (some formulations of mesalamine do not contain phthalates).[6] The study showed that exposures from phthalate containing medications can far exceed population levels from other sources.[6] DBP in medications raises concern about health risks due to the high level of exposures associated with taking these medications especially in vulnerable segments of the population, including pregnant women and children.[6]
In 2008 the United States National Research Council recommended that the cumulative effects of phthalates and other antiandrogens be investigated. It criticized US EPA guidances, which stipulate that when examining cumulative effects the chemicals examined should have similar mechanisms of action and/or similar structures, as too restrictive. Instead, it recommended that the effects of chemicals which cause similar adverse outcomes should be examined cumulatively.[7]:9 Thus the effect of phthalates should be examined together with other antiandrogens, which otherwise may have been excluded because their mechanisms or structure were different.
REFERENCE:
http://en.wikipedia.org/wiki/Phthalate