A group of senators is expected to demand that eBay, Alibaba, and Craiglist explain how they plan to counter the illegal sale of vaping products on their platforms in letters they will send to the companies on Monday.

In June, The Verge reported that e-commerce platforms like eBay were littered with e-cigarette listings. Some of these listings appeared to be authentic, brand-name products like Juul pods, while others were counterfeit. These items violate eBay’s policies, and while the company uses a variety of tools to remove the listings, it’s still fairly easy to purchase tobacco products and e-cigarettes on the platform. In addition to violating platform rules, there’s no method to verify that the purchaser is of legal smoking age either.

“Juul items are not allowed to be sold on eBay,” an eBay spokesperson told The Verge back in June. “Over the past year, we have blocked or removed hundreds of thousands of listings for e-cigarettes.”

“All of these products – real or counterfeit – are dangerous and shouldn’t be available on your platform”

The group of senators, led by Sen. Richard Blumenthal (D-CT), includes Sens. Elizabeth Warren (D-MA), Jeff Merkley (D-OR), Jeanne Shaheen (D-NH), Ed Markey (D-MA), Bob Menendez (D-NJ), and Sherrod Brown (D-OH).

“In allowing these products to secure a foothold on your marketplace, you are not only supporting these companies in their endeavor to increase youth demand and access, but also assisting profiteering counterfeiters seeking to cause teens further harm,” the senators wrote. “Regardless, all of these products – real or counterfeit – are dangerous and shouldn’t be available on your platform.”

Their questioning of these platforms comes less than a week after President Donald Trump announced that his administration would seek to ban all flavored e-cigarette products from the American market. Over the past few weeks, hundreds of people across the country have grown ill and others have died due to deadly lung illnesses that have been linked to e-cigarette use. It’s still not clear what exactly is causing these illnesses, but they have led lawmakers to consider blanket bans until more is known. Any ban affecting vaping products in brick-and-mortar stores is likely to push more people who use the devices toward black market sales.

“If eBay continues to operate as it has, providing unfettered access to legitimate and counterfeit e-cigarettes, this flavor restriction will be meaningless,” the senators said.

This isn’t the first time eBay has been criticized for hosting these listings either. In April 2018, the Food and Drug Administration notified the company that Juul products were being sold on its platform. But even after the FDA contacted them, eBay is still awash in vape products.

In their letters to eBay, Alibaba, and Craigslist, the senators probe the companies on their tobacco policies and how they plan to improve enforcement in order to keep vape products and e-cigarettes off their platforms. The companies have until October 1st to respond to the senators.

“More must be done to ensure that tobacco products, some of which could be adulterated, do not secure a foothold on your marketplace,” the senators wrote to the e-commerce companies. “You must also ensure that your marketplace does not contribute to the addiction of a new generation of tobacco users and the ongoing outbreak of vaping-related illnesses and lung injuries.”