I wouldn't trust DEA or NIDA publications unless they have citations from reputable sources. The British Medical Association statement is true, however. Joints have more tar (I've heard up to the equivalent of about a pack from a reputable source- Lester Grinspoon), but THC may act as an anti-inflammatory agent that prevents as much damage to the lungs (in the form of cancer, but not bronchitis etc.) as cigarettes.