The FTC put 20 manufacturers and marketers of dog-poop bags on notice this week, warning them that claims their bags are biodegradable or compostable could fall afoul of truth-in-advertising regulations.

Here’s the scoop: The problem with these kinds of environmental claims is that they don’t take into account how we dispose of the bags when we pick up after our dogs.

To be called “biodegradable,” a product should break down within a year after being thrown out. “Most waste bags, however, end up in landfills where no plastic biodegrades in anywhere close to one year, if it biodegrades at all,” the agency noted.

Likewise, people assume the word “compostable” means you could take the bags home and compost them, or bring them to a composting center. But the risk of disease makes composting dog poop at home risky, and most facilities won’t accept it. “Therefore, compostable claims for these products are generally untrue,” the FTC said. The companies (which the FTC didn’t name) have to change how they advertise the bags and inform the agency.

IN-DEPTH

-- Martha C. White, NBC News contributor