The just-released study says 60 percent of children's car seats sold in the U.S. contain one or more hazardous chemicals.
The Ecology Center, an environmental non-profit organization, tested 150 seats of 2011 models and found flame retardants, arsenic, lead and other heavy metals.
The Center said the good news is seats fared better than in previous years. Since 2008, when the group first started its research, there has been a 64-percent improvement in car seat rankings.
Healthystuff.org, a project of the Ecology Center, picked the chemicals of concern based on studies showing links to reproductive problems, developmental and learning disabilities, hormone imbalances and cancer.
The study has no bearing on how well the seats perform in a car accident.