Phthalate

Phthalates, or phthalate esters, are esters of phthalic acid and are mainly used as plasticizers (substances added to plastics to increase their flexibility). They are chiefly used to turn polyvinyl chloride from a hard plastic into a flexible plastic.

Properties
Phthalate esters are the dialkyl or alkyl aryl esters of phthalic acid (also called 1,2-benzenedicarboxylic acid, not be confused with the isomeric terephthalic or isophthalic acids ); the name phthalate derives from phthalic acid, which itself is derived from word "naphthalene". When added to plastics, phthalates allow the long polyvinyl molecules to slide against one another. The phthalates show low water solubility, high oil solubility, and low volatility. The polar carboxyl group contributes little to the physical properties of the phthalates, except when R and R' are very small (such as ethyl or methyl groups). They are colorless, odorless liquids produced by reacting phthalic anhydride with an appropriate alcohol (usually 6 to 13 carbon).

As of 2004, manufacturers produce about 363 thousand metric tonnes (800 million pounds or 400 000 short tons) of phthalates each year. They were first produced during the 1920s, and have been produced in large quantities since the 1950s, when PVC was introduced. The most widely-used phthalates are di-2-ethyl hexyl phthalate (DEHP), diisodecyl phthalate (DIDP) and 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.

Phthalates are also frequently used in soft plastic fishing lures, nail polish, adhesives, caulk, paint pigments, and sex toys made of so-called "jelly rubber." Some vendors of jelly rubber sex toys advise covering them in condoms when used internally, due to the possible health risks. Other vendors do not carry jelly rubber sex toys, in favor of phthalate-free varieties. The Dutch office of Greenpeace UK sought to encourage the European Union to ban sex toys that contained phthalates.

Though controversial, phthalates are still being used in a variety of household applications (shower curtains, adhesives, perfume), modern pop-culture electronics and medical applications such as catheters. Notable recent examples include Apple Inc.'s iPhone and iPod, and personal computers. The company has been criticized by environmental supporters claiming that tests on a commercially-purchased iPhone returned "toxic" levels of the chemical, prompting public declarations for change due to its associated hazards. .

Health effects
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. Phthalates are controversial because high doses of many phthalates have shown hormonal activity in rodent studies. Studies on rodents involving large amounts of phthalates have shown damage to the liver and testes and cause birth defects. In addition, a recent British study showed that the phthalate di(n-butyl) phthalate (DBP) or its metabolite monobutyl phthalate (MBP) suppresses steroidogenesis by fetal-type Leydig cells in primates as in rodents.

Initial rodent studies on carcinogenity were rather alarming, indicating hepatocarcinogenity. Following this result, diethyl hexyl phthalate was listed as a possible carcinogen by IARC, EC and WHO. Later studies on primates showed that the mechanism was specific to rodents - humans are resistant to the effect. The carcinogen classification was subsequently withdrawn.

In 2004, a joint Swedish-Danish research team found a very strong link between allergies in children and the phthalates DEHP and BBzP.

A 2005 study by Swan et al. reported that human phthalate exposure during pregnancy changed an anogenital measurement in the baby boys later born, a change that in rodents exposed to phthalates is associated with genital abnormalities. In this study urine samples were collected from pregnant women in four United States cities. All were found to have levels of phthalate residues in their urine. Upon birth of the children whose mother's urine had been previously measured, the genital features and anogenital distance were measured and correlated with the residue levels in the mother's urine. In boys, the highest levels of residue were seven times more likely to have a shortened anogenital distance. The science behind this study was questioned by chemical industry advocates, and a National Toxicology Program expert panel concluded that anogenital distance is a "'novel index' whose relevance in humans 'has not been established,'" and that there is "insufficient evidence in humans" that DEHP causes harm. A more recent study of anogenital distance states "Whether anogenital distance measurements in humans relate to clinically important outcomes, however, remains to be determined".

The reporting by the media of the Swan study has been criticized by STATS. They claim that the methodology used, including a small, homogeneous study group that was not pulled from a wide variety of regions, cannot be used to definitively claim widespread problems related to phthalates. The criticism also states that the media overstated the findings in the report.

In addition, in a 2004 study by the Children's National Medical Center and The George Washington University School of Medicine in Washington, D.C, it was found that "adolescents exposed to significant quantities of DEHP as neonates showed no significant adverse effects on their physical growth and pubertal maturity." There was no correlation between heightened residue levels and smaller penis sizes. It should be noted, however, that this study examined children exposed intravenously to phthalate diester, and intravenous phthalate diester exposure results in relatively little metabolic conversion of the relatively nontoxic phthalate diester to its toxic metabolite (phthalate monoester).

The authors of a study of Finnish boys with undescended testis hypothesized, based on their findings, that exposure to a combination of phthalates and anti-androgenic pesticides may have contributed to their condition.

In 2007, a cross-sectional study of U.S. males conducted by researchers at Rochester School of Medicine and Dentistry concluded that urine concentrations of four phthalate metabolites correlate with waist size and three phthalate metabolites correlate with the cellular resistance to insulin, a precursor to Type II diabetes. The authors note the need for follow-up longitudinal studies, as waist size is known to correlate with insulin resistance.

Research on phthalates in the environment published in 2008 asserted that many baby care products containing phthalates are source of exposure for infants. The authors "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. 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."

United States
Some phthalates will be restricted in the U.S. state of California (for children's toys) starting in 2009. In Connecticut, state legislators are considering a bill that would ban phthalates in children's products.

European Union
The use of some phthalates is restricted in the European Union for use in children's toys. DEHP, BBP, and DBP are restricted for all toys; DINP, DIDP, and DNOP are restricted only in toys that can be taken into the mouth. The restriction states that the amount of phthalates may not be greater than 0.1% mass percent of the plasticized part of the toy.

There are no other specific restrictions in the European Union, and the phthalates mentioned are allowed in any concentration in other products. Other phthalates are not restricted.

Identification in plastics
PVC plastics - for recycling reasons are labelled "Type 3" - are typically used for various containers and hard packaging, medical tubing and bags may contain and leach phthalates.

Media

 * Interview with Mark Schapiro from Fresh Air (NPR) ; November 26, 2007
 * Phthalates Now Linked to Fat, Related Health Risks, University of Rochester Medical Center, March 14 2007.
 * New Scientist and Scientific American articles on Environmental Health Perspectives report; see Research.
 * Unsafe Sex Toys with Violet Blue
 * The Facts on Phthalates and Sex Toys
 * Naughty by Nature: Ever thought about the toxins in your sex toys? by Emily Gertz, "Grist magazine", 6 December 2005
 * Panel Ranks Risks of Common Phthalate: Additional research underscores concerns about DEHP that were first expressed in 2000 report, Bette Hileman, Chemical and Engineering News, NOVEMBER 14, 2005, 83(46):32–36.

Research

 * The Association between Asthma and Allergic Symptoms in Children and Phthalates in House Dust: A Nested Case-Control Study
 * DIDP, DINP, and DBP - Risk Assessment Reports by the European Chemicals Bureau (ECB).

Sources suggesting low/no health risks

 * Phthalates Information Centre; an initiative of the European Council for Plasticisers and Intermediates (ECPI)
 * Phthalates Information Center; from the American Chemistry Council, Inc.
 * Phthalates and Human Health, by Kenneth Green, D.Env.; Director of the Environmental Program at Reason Public Policy Institute, Reason Foundation, 2000

Ftaláty Ftalat Phthalsäureester Φθαλικές ενώσεις Ftalato Phtalate Ftalati Ftalaat Ftalany Ftalaatti Ftalater

Ftaláty Ftalat Phthalsäureester Φθαλικές ενώσεις Ftalato Phtalate Ftalati Ftalaat Ftalaatti Ftalater