Why is green tea so popular in Asia while black tea is all the rage in the West? Tom Sandage's A History of the World in Six Glasses proffers a theory:

The first tea was green tea, the kind that had always been consumed by the Chinese. Black tea, which is made by allowing the newly picked green leaves to oxidize by leaving them overnight, only appeared during the Ming dynasty; its origins are a mystery. It came to be regarded by the Chinese as suitable only for consumption by foreigners and eventually dominated exports to Europe. Clueless as to the origins of tea, Europeans wrongly assumed green and black tea were two entirely different botanical species. ...

It is not too much exaggeration to say that almost nobody in Britain drank tea at the beginning of the eighteenth century, and nearly everybody did at the end of it. ... [There was a] widespread practice of adulteration, the stretching of tea by mixing it with ash and willow leaves, sawdust, flowers, and more dubious substances--even sheep's dung, according to one account--often colored and disguised using chemical dyes. Tea was adulterated in one way or another at almost every stage along the chain from leaf to cup. ...

Black tea became more popular, partly because it was more durable than green tea on long voyages, but also as a side effect of this adulteration. Many of the chemicals used to make fake green tea were poisonous, whereas black tea was safer, even when adulterated. As black tea started to displace the smoother, less bitter green tea, the addition of sugar and milk helped to make it more palatable.

So there you have it. But why is black tea safer "even when adulterated"? Surely it doesn't have the power to neutralize the "dubious substances" on its own, right?