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Studies Link Class of Chemicals to Certain Medical Risks

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Feb 10, 2004 3:54PM
Knight-Ridder / Tribune Business News – 

A group of common chemicals found in indoor air, some perfumes and plastic tubing used in hospitals may be more prevalent and dangerous than previously thought -- with pregnant women and infants especially at risk, new studies say.

New research on the substances, called phthalates (pronounced THAL-aytes), finds that at least one type can disrupt the human hormone system -- putting pregnant women at risk for delivering premature babies, damaging sperm in some men, and harming reproductive systems of children.

Recent studies also refute the notion that humans are only exposed to phthalates orally; the studies have established that indoor exposure to the chemical is more widespread than previously thought and that modest levels of some phthalates can be harmful.

Phthalates are one of the most ubiquitous manmade substances in the environment. They are found in everything from vinyl flooring to cosmetics and toys. Their popularity stems from the fact that the chemical's molecules easily slip and slide past each other, making the materials they are in pliable. 

A recent study concluded that an average person consumes 5.8 milligrams of phthalates daily -- almost a milligram higher than the acceptable daily dose assigned by the Environmental Protection Agency.

Because phthalates have been detected in substantial doses in the human body, they are now among the most closely studied chemicals. Concern over phthalates and their health effects has been so strong that the chemical has been banned from the manufacture of many toys in Europe, with some toymakers in the United States following suit.

Three studies, published last year by the National Institute of Environment Health Sciences, measured the effects of phthalate exposure in humans.

One study found that phthalate exposure in fetuses may contribute to premature birth. Of 84 infants in that study, scientists found 88 percent had phthalates in their blood. The study also cited reports that a particular kind of phthalate -- diethylhexyl phthalate or DEHP -- can inflame the uterus of expectant mothers.

A second study shows that adult men are also at risk from phthalate exposure. The study found a correlation between phthalate exposure and damaged DNA in sperm in 168 men studied at the fertility clinic at Massachusetts General Hospital.

A third study, released last November, established that all women who participated in a phthalate study showed traces of the chemical in their urine and that exposure came through inhalation.

A separate study, by the Silent Spring Institute, which sought to find out why breast-cancer rates are higher on Cape Cod than in other parts of Massachusetts, established that phthalates were present in high concentrations in the indoor air of all 120 homes tested.

Those studies counter the generally held belief among scientists that humans only ingest phthalates orally, topically or through some medical procedures.

DEHP, the most toxic form of phthalate, has been found in high concentrations in medical tubing and intravenous bags. DEHP is well known for leaching from the tubing, especially when coming into contact with liquids that have a high fat content.

As a result, infants who undergo medical procedures requiring plastic tubing are exposed to high DEHP rates. Laboratory tests using rats have established that high DEHP exposure rates, like those received by infants in neonatal procedures, can cause reproductive-system abnormalities such as shrunken testes.

Kim Boekelheide, professor of medical sciences and a toxicologist at Brown University, agrees that scientific studies prove that premature infants who undergo multiple medical procedures may be at risk of phthalate exposure. But Boekelheide cautioned that the lack of data on phthalates makes any risk a "hypothetical risk."

However, that risk has been enough to make some hospitals, such as Hasbro Children's and Boston's Brigham and Women's, use phthalate-free or specially coated tubing in neonatal intensive-care units.

Hasbro Children's Hospital has used specially coated tubing since 2002, when the Food and Drug Administration issued an advisory on the dangers of phthalates. The tubing acts as a barrier to prevent the leaching of phthalates to infants undergoing surgical procedures, said Nicole Gustin, spokeswoman for the hospital.

The dangers of phthalate tubing have been a concern at Women & Infants hospital since toxicologists from the University of Rhode Island brought up the issue to its staff, said Dr.

William Cashore, associate chairman of pediatric medicine at the hospital. However, Cashore, the hospital staff and its tubing supplier could not say definitively whether the hospital has gone phthalate-free or when, said Amy Blustein, spokeswoman for Women & Infants.

Susan Wilburn, senior specialist in environmental safety at the American Nurses Association, says many hospitals have yet to go phthalate-free in their neonatal-care units.

"People should be concerned if they have a baby in a neonatal intensive-care unit," Wilburn said. "They should advocate for phthalate-free care."

Studies on what happens to the reproductive development in infants who have been exposed to phthalates are few.

Scientists are just now beginning to grapple with the fact that, in some cases, phthalate exposure may have little effect on a parent but may cause abnormalities in the reproductive organs of their male children, said Ted Schettler, doctor at the Science and Environment Health Network.

"We simply don't know if the children are being harmed," he said.

DEHP phthalates are also found in the fragrances of Christian Dior's Poison, Oscar, and Fire and Ice cologne spray, according to an analysis published by the Environment Working Group, a nonprofit research organization based in Washington, D.C., that has studied the chemical.

Phthalates are used in fragrances to make them last longer, although consumers will not find the chemical listed on fragrance packaging since the Food and Drug Administration does not require manufacturers to list phthalate as an ingredient. DEHP use in fragrances was banned by the European Union in 2000.

The phthalates group of chemicals is so widely used in cosmetic products that they were found in 52 of 72 products tested, including 9 of 14 deodorants and 6 of 7 hair gels tested in the published study.

Despite the recent studies, scientists agree that more research needs to be done on the effect of phthalates on humans.

Chemical industry scientists say phthalates are safe and exist well within acceptable levels in most products.

"Phthalates have been used for 50 years with no health concerns," said Marian Stanley, of the American Chemistry Council. Stanley, whose office is funded by phthalate manufacturers such as ExxonMobil, said that phthalates have been a boon to the medical industry for allowing easier use of blood bags and blood transfusions -- use that was once hindered by the fragility of glass.

A wide-ranging study on the effects of phthalates in infants exposed to the chemical will soon be under way, according to Russ Hauser, associate professor of occupational health at Harvard University.

That study will track the children of 100,000 pregnant women in Europe and the United States. It will follow the children into adolescence to gauge the effects of phthalates on the development of their reproductive systems, and will be the most extensive study on the subject to date, he said.



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