ENDOCRINE DISRUPTORS Page 2

How Much Phthalates Are Produced?

Exact amount of phthalates produced each year varies from source to source. One figure cited was that worldwide in 1999, the phthalates volume manufactured was about 10 billion pounds (valued at U.S.$5 billion), with an average annual growth rate of 2% to 3% according to one estimate. Another figure has researchers estimated that more than 18 billion pounds are used each year. Still others estimated that as of 2004, manufacturers produce about 363,000 metric tons (800 million pounds or 400,000 short tons) of phthalates annually according to another estimate. They were first produced during the 1920s, and have been produced in large quantities since the 1950s, when PVC was introduced commercially. In Australia, industry uses approximately 12,000 tons of phthalates each year to plasticize PVC products. In Sweden, approximately 5,000 to 6,000 tons of phthalates—including di(2-ethylhexyl) phthalate (DEHP)—are used annually. Even in 1969, more than 800 million pounds were produced annually (according to the U.S. Tariff Commission, 1971).

Phthalates substitutes are available but they cost about 50% more, or even double in the case of one phthalate. More than 90% of the plasticizer volume produced annually goes into PVC. Without phthalates, PVC is brittle and hard and has little commercial application or value.

Ever since its popular use in the 1920s and 1930s, phthalates have leached into drinking water, food, and air. Phthalates are found all over the world, from the most populated urban areas to the most remote corners of the earth. Phthalates leach easily from products because in general they are not chemically bound to the product matrix and may thus migrate readily (Högberg et al., 2008).

Chemistry of Phthalates: What Are Phthalates?

Phthalate plasticizers are colorless liquids (similar in viscosity and appearance to vegetable oil) with a faint odor, and they are insoluble in water. They are, however, miscible in mineral oil, hexane, and most organic solvents, which makes them readily soluble in bodily fluids, such as saliva and plasma. 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. Of the ester plasticizers, standard phthalate esters comprise more than 85% of the tonnage produced annually. Phthalates command the market because of their low cost and availability.

The basic structure of "phthalate" is the benzene ring consisting of six carbons and six hydrogen atoms (the left-most part of the structure) bonded with two esters (which are the two carbon atoms double-bonded to two oxygen atoms on one side and single-bonded to two other oxygen atoms on another side). When one compares the structures of the phthalates, one sees the similarity, as in Bis(2-ethylhexyl)phthalate and diisodecyl phthalate above.

A list ofphthalates commonly used in consumer and industrial products worldwide

Typically because phthalates are not chemically bound to the product matrix, they migrate out of the product easily and cause extensive exposure among humans and animals that come into contact with them (Högberg et al., 2008).

Phthalates in the Environment

Effects on Fish, Frogs, and Other Amphibians in the Wild: Reproductive, Endocrine, Immune, Genotoxic, and Nephrotoxic Damages.

Phthalates and their metabolites are excreted from human urine and wastewater (such as water that washes off cosmetics, facial cream, lotion, shampoo). Phthalate-containing wastewater reaches the environment via treated sewage discharged into streams, rivers, lakes, oceans, and other bodies of water. Phthalates also reach the natural environment via pesticides, industrial lubricants, and phthalate-containing garbage humans throw away. Because everything humans use eventually get disposed of into the environment, it is inevitable that phthalates are found in the environment.

Humans and wildlife are exposed to phthalates and other environmental pollutants which can interfere with endocrine-signaling pathways in the body. For about four decades (since the 1970s), hundreds of scientists conducting research all over the world have found that phthalates and other environmental pollutants (such as pesticides, synthetic industrial lubricants and solvents) can disrupt the endocrine functioning of wildlife species, thus causing permanent alterations in the structure and function of the endocrine system.

Since phthalates are extensively used as plasticizers decades ago, researchers have found them in the rivers and lakes. In an article published in January 1973, a MIT researcher has found that the phthalate concentration increases as one moves upstream: "Phthalates are added to the river from one or more sources which are located above river mile. As this contaminated water flows downstream, more water is added from runoff and other sources, thus diluting the phthalates. In addition, biological activity in this slowly flowing river [Charles River] also tends to reduce the phthalate concentration as the water moves downstream. The two samples taken at river mile 1 but at two different depths differ significantly. This is certainly due to the severe vertical stratification exhibited by the river at this location (Hites, 1973).

Although phthalates' concentrations may decrease due to dilution by river water, even the low concentrations of phthalates affect a wide variety of wildlife in the rivers (e.g., fish, frogs and tadpoles, and other amphibians). Numerous scientific studies focusing on how phthalates affect aquatic animals have been conducted by researchers since the 1970s; we present only a few studies here.

Photos: A deformed frog with five legs (left) and a chytrid-infected (fungus-infected) dead frog floating in the water (right). (Photos courtesy of Wikipedia).