MADISON, Wis. (AP) — Wisconsin Attorney General Josh Kaul announced Tuesday that he has joined nearly 40 other state attorneys general in an investigation into whether electronic cigarette giant Juul Labs Inc.’s advertising targeted underage youth.

The 38-state probe also will center on the company’s claims about the nicotine content and safety of its products, Kaul said.

Juul spokesman Austin Finan said the company will seek to earn society’s trust by working cooperatively with attorneys general, regulators and public health officials to fight underage use of vaping products.

The National Youth Tobacco Survey conducted by the U.S. Food and Drug Administration and the Centers for Disease Control found nearly 21% of high school students used vaping products in 2018.

California, Massachusetts, New York and Pennsylvania, have sued Juul over advertising they allege targets young people. Juul bought advertisements on websites designed for teens and children, like, and the, according to Massachusetts’ filing.

President Donald Trump signed a law in December that bars tobacco sales, including vaping products, to anyone under 21. A bill adopting the federal law is working its way through the Wisconsin Legislature. Current state law bars tobacco sales to anyone under 18.