Feb. 4, 2008— -- Some environmental medicine experts worry that parents using any one of dozens of baby products could be exposing their children to chemicals that could hurt their reproductive ability later on in life.
In a new study, University of Washington researchers found evidence of chemicals called phthalates in the urine of 163 infants exposed to a baby product such as shampoo, lotion or powder. The study was released Monday in the journal Pediatrics.
However, there still exists little evidence that phthalates — man-made chemicals that are found in many products from tubing to cosmetics — cause any harm to humans.
Still, the researchers noted that the fact that evidence of the substances were found in the urine of more than 80 percent of the babies in the study suggests more should be done to identify products that contain these chemicals.
"We still do not know what the true long-term effects of these chemicals are," said lead study author Dr. Sheela Sathyanarayana, pediatric environmental health fellow at the University of Washington in Seattle. "But we do have more evidence that they are linked to human health effects at concentrations we are exposed to every day."
Some environmental medicine experts not affiliated with the study said the research should sound an alarm to both parents and pediatricians.
"Parents and physicians should pay close attention to these results," said Bernard Weiss, professor of environmental medicine and pediatrics at the University of Rochester School of Medicine and Dentistry in Rochester, N.Y.
"We already possess substantial data demonstrating that the developing child is at risk for a number of adverse health effects arising from phthalate exposure," he said.
Dr. Bruce Lanphear, director of the Environmental Health Center at Cincinnati Children's Hospital Medical Center, agreed that concern is warranted.
"Parents and doctors should be worried about their children's exposures to phthalates and other chemicals that are largely untested for toxicity," he said. "For far too long, we have allowed industries to market their product without evidence that the products are safe when used as directed.
"The public health implications of these products are considerable."
Despite the finding that the chemicals may be more ubiquitous in infants than once thought, the new research is unlikely to quell the debate over whether phthalates are indeed harmful to babies.
While most past research has been done in mice and other animals, a growing number of studies are looking at the possible effects of the chemicals on humans. And thus far, most of these studies, conducted in both the United States and Europe, have not suggested that the chemicals have a detrimental effect on human health.
"The study did not find adverse effects from phthalates, nor was it designed to find such effects," said Dr. Marcel Casavant, chief of pharmacology and toxicology at Nationwide Children's Hospital in Columbus, Ohio. "That phthalates are present in most or all of us isn't particularly new; what the study adds is that absorption of phthalates through the skin seems to be an important way many babies get their phthalates.
"I don't think this information should worry parents."
Moreover, in a report released by the U.S. Centers for Disease Control and Prevention in January 2003, researchers compared the phthalate exposure of more than 5,000 Americans of various ages and ethnic groups to government-established maximum safe exposures for the chemicals.
In all demographic categories, the amount of phthalates to which people in the United States were routinely exposed fell far short of the established safe limits. Even for those in the 95th percentile — in other words, those who experienced the most exposure to these chemicals — their total exposure fell short of the established limits.
Additionally, the U.S. National Toxicology Program recently issued reports on six different phthalates it reviewed. The report classified the potential risk to human reproductive and developmental health as "minimal" or "negligible."
Still, the continued scrutiny of the effects of these chemicals in humans attests to the concern surrounding their use. Study author Sathyanarayana said studies are under way to reassess the safe levels of these chemicals for humans. But she added that it might not be just the concentration of these chemicals, but also the fact that we are constantly and consistently exposed to them, that could lead to health effects.
While initial concerns over the chemicals had to do with possible cancer-causing effects — effects now largely discredited by the available research — some researchers are currently more worried about the supposed potential of these chemicals to bring about a variety of reproductive problems later in life.
"There is considerable evidence in animal studies that phthalates disrupt the endocrine system," Lanphear said. "Although the data are insufficient for humans, previous research with rodents and other animals suggest that the results of toxicity studies in animals are relevant to humans."
And Weiss agreed that exposures early in life could lead to effects later on.
"Testicular cancer, diminished sperm counts and metabolic abnormalities … are especially worrisome because they constitute what we call 'silent toxicity,'" Weiss said. "They remain dormant for as long as decades, so they are not readily connected to chemical exposures during prenatal life or infancy."
Weiss and Lanphear said the fact that the eventual effects of phthalate exposure remain unknown points to a need for greater regulation of the chemicals by the U.S. government. Such regulation would follow actions taken in 2006 by the European Union, which banned the use of six phthalate softeners used in plastic toys designed to be placed in the mouth by children younger than 3.
Lanphear, for one, said that a similar move by the U.S. government would be a wise move.
"They should ban phthalates until they have proven they are innocuous, especially if there are safe substitutes," he said.
"The U.S. government seems paralyzed these days," Weiss agreed. "However, the EU's actions have economic consequences for U.S. companies, so they may force change."
Regardless, Lanphear said, there are steps that parents can take if they are worried about their young children's exposure to the chemicals. Specifically, he recommends that parents who wish to keep their children's exposure to phthalates to a minimum should reduce the amount of cosmetic products they use on their babies to the minimum needed for proper hygiene.
"As a parent, I would choose to limit my child's exposure to phthalates, including minimizing exposures to products containing phthalates, such as cosmetics and plastic toys," he said. "As such, I would preferentially purchase products that do not contain phthalates. There would be a market for these products."