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."