Open a cereal box or a carton of juice, breathe in an asthma drug from an inhaler, or pop an antihistamine pill out of a plastic pouch’s metal foil. You are probably thinking about the product you’re about to consume and not about its packaging—except, perhaps, for a twinge of regret about contributing to landfill waste. But here’s something to keep in mind: Even when the wrapping comes off, you inevitably ingest some of the container.