In 1992, British American Tobacco had its Canadian affiliate, Imperial Tobacco Canada, destroy internal research documents that could expose the company to liability or embarrassment.

Here's the abstract of a paper published in the Canadian Medical Association Journal by David Hammond, Michael Chaiton, Alex Lee, and Neil Collishaw: Destroyed documents: uncovering the science that Imperial Tobacco Canada sought to conceal. The abstract contains a link to the full article.

This is about research that was funded by the tobacco industry. Two of their conclusions:

• Second-hand smoke is, in fact, more toxic than mainstream smoke, especially for low-delivery cigarettes.
• People smoking filtered cigarettes inhaled more smoke to get about the same amount of nicotine they'd get from unfiltered.