Sneezing powder considered harmful

The history of sneezing powder is unexpectedly fascinating, a tale of an obsessive prankster, whose burning passion to make people sneeze drove him to out-and-out chemical warfare:

No one's entirely sure what Adams used to make Cachoo. It depends on what he had easy access to. He worked for a company that made coal tar products, specifically dyes. Coal tar is what gets leftover when coal is made into more purified fuel. It's a viscous black substance that can be used to pave roads, but is also added to medicated shampoo, and used as a base for clothing or even food dye. There are plenty of by-products in the process that can – but probably shouldn't – be used as nasal irritants. These would be easily accessible, and, if they were by-products, cheap to acquire.

But more recent chemists think that to make Cachoo, Adams was actually pilfering one of the dyes that he was supposed to be selling. Dianisidine is a chemical that, with coal tar, makes a beautiful blue dye. It's also carcinogenic and, according to the CDC should be flushed from every part of the body it makes contact with. A sneeze response would certainly help with that. Dianisidine was first discovered in 1894, when people noticed that it, in combination with copper salts, made a pretty color on fabrics that set in faster than indigo. People would have been using it a great deal, especially in the manufacturing centers, testing out new products.

Unfortunately, over a few years they found out that it ran when exposed to acid, or even heavy perspiration, bleeding blue on anyone who wore clothing dyed with it. Its color might have worked for soap products, but it was useless in clothing manufacturing. The repeated testing, would have given Adams ample opportunity to see people sneezing. The eventual abandonment of it as a potential clothing dye may have given him the ability to pick it up at a good price for his initial stock of Cachoo. But is that what he did?