The world’s largest chocolate companies promised to eradicate child labor from their supply chains 20 years ago. But today, these same companies say they cannot guarantee that the chocolate you buy is free from child labor.A key ingredient in chocolate — cocoa — is harvested from farms in Ivory Coast, and many of the young boys engaged in this dangerous labor come neighboring Burkina Faso, About two-thirds of the world’s cocoa supply comes from West Africa, and in 2015 the U.S. Labor Department reported that more than 2 million children were performing dangerous labor to harvest cocoa. These kids are swinging machetes, carrying heavy loads, spraying pesticides — all considered the “worst forms of child labor” under international law. When asked this spring, representatives of some of the biggest and best-known brands — Hershey, Mars and Nestlé — could not guarantee that any of their chocolates were produced without child labor.“I’m not going to make those claims,” an executive at one of the large chocolate companies said..One reason is that nearly 20 years after pledging to eradicate child labor, chocolate companies still cannot identify the farms where all their cocoa comes from, let alone whether child labor was used in producing it.