Via random clicking, this remarkable Bloomberg article:
...Acetic anhydride has legal uses in laboratories and factories—the most common use is in the production of cigarette filters. But under international drug laws it’s one of the most strictly controlled “precursor and essential chemicals” for the production of illegal narcotics. For 30 years the U.S. government has aggressively pushed almost every nation in the world to sign on to global treaties and pass domestic laws to keep potential drugmaking chemicals away from narcotics syndicates. Acetic anhydride was placed in the highest category of control in 2001. Yet the acetic anhydride seized that morning in Sinaloa was bottled, branded, and sold in Mexico by a $12.3 billion publicly traded U.S. company, Avantor Inc.
During the decade-long U.S. heroin epidemic, Avantor has cultivated a remarkable line of business: selling acetic anhydride across Mexico in containers that are big enough to make lucrative quantities of illegal narcotics but small enough to load into the trunk of a car. Sales come via a network of distributors, online sellers, and stores spread across the country...It sounds like there are a lot of different things to blame here, but it's pretty clear that Avantor knows that it is selling acetic anhydride to manufacture heroin (i.e. someone would have been asking 'why are we selling acetic anhydride in such large quantities in 5 gallon containers?')
