A Pot Knockoff Sometimes Made With Household Acid Draws Scrutiny

A little-known substance derived from hemp is flying off the shelves of U.S. gas stations and smoke shops, offering users a cheap and convenient high even in states where marijuana isn’t legal. But large cannabis producers are now pushing to clamp down on Delta-8 THC amid worries that a lack of oversight means heavy metals and unexpected intoxicants are cropping up in some of the products.

The cannabis compound has proliferated in gummies, joints and vape pens, with sales more than doubling in the past year across the country. Despite being almost chemically identical to federally outlawed forms of marijuana, ...