A new study finds online e-cigarette retailers are not consistently obeying laws designed to prevent the sale of vaping products to minors, CNN reports.

Some online retailers are ignoring regulations regarding age verification, shipping methods and flavor restrictions, according to researchers at the University of California San Diego. They looked at attempts to buy flavored nicotine vaping products from 78 websites and have them delivered to private homes.

Among 105 deliveries, delivery personnel scanned the ID of the person who received the package only one time. The study found 78% of buyers reported no interaction with delivery personnel; 15% of buyers spoke with delivery personnel but did not have their IDs checked; and 6% of buyers had their IDs checked but not scanned.

In 2019, Congress raised the legal purchasing age for tobacco products from 18 to 21. This includes a requirement for retailers to verify photo ID.

“There are longstanding surveillance systems in place that help implement laws at brick-and-mortar stores, but we do not have a system in place for online retailers,” Eric Leas, Ph.D., M.P.H., said in a university news release. “The results of this study highlight the need for greater oversight and enforcement of online tobacco retailers.”