Democrat Diana Urban of North Stonington is scheduled to join the Coalition for a Safe and Healthy Connecticut on Monday for a news conference at the Legislative Office Building in Hartford.
They've expected to discuss potential toxic chemicals that can be found in children's costumes.
Afterward, a group of children is expected to deliver cards to Gov. Dannel Malloy's office to show their concern about the issue.
Connecticut lawmakers have tried to address chemicals in children's products over the years.
In 2011, a law took effect banning the plastics chemical bisphenol-A from infant formula, baby food containers and a range of reusable food and drink containers.