The 1994 JAMA study focused in part on a study of thousands of women from five metropolitan areas (Atlanta, Ga, Houston, Tex, Los Angeles, Calif, New Orleans, La, and the San Francisco Bay Area, Calif.), none of whom were smokers. One large group was composed of women who had been diagnosed with lung cancer. The other was composed of women who had never been diagnosed with lung cancer.

The doctors interviewed the women and their spouses from both groups to determine how many smokers were in the household, how many packs per week they smoked at whatever stages of their life, etc. They then crunch a whole pile of numbers per standard methodologies, and determined that living with an average smoker gave a 30% excess risk of lung cancer. They also observed the expected dose-response-- women who lived with heavy smokers (or lived with smokers for longer) had a higher excess risk than those who lived with light smokers (or lived with smokers for shorter).

The article was never retracted or amended, but it is cited an awful lot. That tells me that the journal's editorial board stands by their conclusions, and a lot of other medical doctors consider it an important study.

Honestly, I can do this for any of the studies. Yes, I trust in sources like the British Medical Journal, but it's because I read journals, and I've written a pile of articles myself. I know what the review process is like, what the standards are for publication, and the tremendous scrutiny placed upon you, particularly in a major journal. That's not a "leap of faith". It's based on years of professional experience.

valguarnera@carrionfields.com