ORONO (AP) — A University of Maine scientist says some bags used to transport pet fish home from aquariums leach a toxic chemical that might kill the animals.

Marine Scientist Heather Hamlin and colleagues report that certain plastic bags with U.S. Food and Drug Administration food-grade approval leach nonylphenol in concentrations highly toxic to fish. The chemical is also found in food packaging, cosmetics and laundry and dish detergents. The university says the chemical binds to estrogen receptors, mimics estrogen, and feminizes and alters fertility in fish.

Hamlin says her work is among a growing body of research highlighting concerns with plastic contaminants. She also says the study will help underscore the difficulty in differentiating “good from bad plastic.”

Hamlin’s findings appear in an issue of the journal Chemosphere.