Phthalates are used to make plastics flexible and stabilize fragrances, and are found in a plethora of consumer products including toys, personal care products and medical equipment.

As reported online today in the journal Pediatrics, Sathyanarayana, from the University of Washington, Seattle, and colleagues measured the levels of nine different phthalate breakdown products in urine from diapers of 163 infants aged 2 to 28 months.

All of the urine samples contained at least one phthalate at measurable levels, they report, and 81 percent of the samples had measurable amounts of seven or more phthalates.

"We found that reported use of baby lotion, baby shampoo, and baby powder was associated with increased concentrations of monethyl phthalate (MEP), monomethyl phthalate (MMP), and monoisobutyl phthalate (MIBP) in infant urine," Sathyanarayana said.

This association was strongest in young infants less than 8 months old, "who may be more vulnerable to developmental and reproductive toxicity of phthalates," the investigators note in their report.

At present, US manufacturers are not required to list phthalate contents on products' package labels, making it hard for parents to make informed decisions, the investigators point out.

"If parents want to decrease exposures for their children, they can try to use lotions, shampoo, and baby powder sparingly unless otherwise indicated for a medical reason," Sathyanarayana suggested.