Some baby teething toys marketed as nontoxic may contain chemicals that could interfere with hormones involved in normal growth and development, a study suggests.

Fifty-nine water-filled, solid or gel-filled teethers were purchased online and tested for 26 compounds that are called endocrine-disrupting chemicals.

All of the products tested positive for one of those chemicals, bisphenol-A, even though most of the teethers were marketed as BPA-free, researchers report in the journal Environmental Science and Technology.

“BPA has been linked in a wide range of adverse health effects including obesity, diabetes, neurological and developmental disorders,” said senior study author Kurunthachalam Kannan, a researcher at the New York State Department of Health and the State University of New York at Albany.

“We need a stringent regulation to make sure that labels do reflect the reality,” Kannan added by email. Researchers didn’t identify specific products or manufacturers by name in the study, which found a range of different parabens and the antimicrobials triclosan and triclocarban in most of the teethers.

In animal studies, endocrine-disrupting compounds such as BPA, parabens and antimicrobials have been shown to interfere with hormones and have harmful developmental, reproductive and neurological effects.

The Food and Drug Administration banned BPA from baby bottles and children’s drinking cups in 2012. But few studies have investigated whether these compounds are used in teethers or whether the chemicals can leech out and be ingested by babies.

The authors said typical teether usage might keep a baby’s exposure below levels deemed unsafe.