Kevin Sabet has it backward in “How Legal Weed Shops Feed the Vaping Crisis” (op-ed, Jan 21). Here in California, not a single case of vape disease has been traced to a legal, state-regulated source, according to the state Bureau of Cannabis Control. Rather, the source of the problem is illicit manufacturers of contaminated goods on the underground market.

Contrary to Mr. Sabet, the Centers for Disease Control and Prevention never examined the safety of state-regulated vapes. Rather, it attributed 16% of vape disease cases...