Parents have been advised not to microwave food for their children in plastic containers, nor put the containers in the dishwasher after use.
The new guidance comes from the American Academy of Pediatrics, which raises concerns about food additives from chemicals within plastic containers.
Putting the containers in a microwave or running them through a dishwasher, the AAP says, increases the chances of dangerous chemicals leaking from the plastic and finding their way into children's food.
Some additives are put directly into the foods, it says, but other additives can come indirectly through chemicals in plastic, glues, dyes, paper, cardboards, and different coatings used for processing and packaging.
Prolonged exposure to said additives can potentially impact brain development, and have been linked to conditions including obesity, autism, attention-deficit hyperactivity disorder, and limited muscle mass and bone strength.
It advises not microwaving or putting in the dishwasher plastics with the recycling codes 3 (for phthalates), 6 (for styrene) and 7 (for bisphenols).
Instead, parents should use glass containers to microwave food, or opt for food products with stainless steel packaging over plastics. Choosing whole foods over processed also reduces the risk of additive contaminations.
"Children are more sensitive to chemical exposures because they eat and drink more, relative to body weight, than adults do, and are still growing and developing," the AAP says.
The AAP is calling for a "more rigorous and transparent" process for how the government designates additives as "generally recognized as safe" for consumption. More than 10,000 food additives currently have that designation.