"Although several studies in people have explored possible associations with developmental and reproductive outcomes (semen quality, genital development in boys, shortened pregnancy, and premature breast development in young girls), more research is needed," a 2005 CDC report said.

The new study, which appears in February's issue of the journal Pediatrics, involved 163 babies. Most were white, ages 2 to 28 months and living in California, Minnesota and Missouri.

The researchers measured levels of several phthalates in urine from diapers. They also asked the mothers about use in the previous 24 hours of baby products including lotions, powders, diaper creams and baby wipes.

All urine samples had detectable levels of at least one phthalate, and most had levels of several more. The highest levels were linked with shampoos, lotions and powders, and were most prevalent in babies younger than 8 months.

John Bailey, chief scientist at the Personal Care Products Council, questioned the methods and said the phthalates could have come from diapers, lab materials or other sources.

"Unfortunately, the researchers of this study did not test baby care products for the presence of phthalates or control for other possible routes of exposure," Bailey said.