@w00dchuck41 - That sounds sinister. I guess breathing in smoke isn't very good for you. Go figure. I wonder how many of the 10 million people with thyroid disorders smoke? According to what you said, only one fifth of smokers get thyroid disorders. That isn't as bad as it could be.
Stress is a common cause for most diseases. It puts a strain on your body because it isn't supposed to be a long term thing. Most people just happen to lead very stressful lives that keep their stress levels high. That's why vacation time is so important.
As for stress causing thyrotoxicosis -- I'm not so sure. How can doctors and researchers tell when everyone is stressed? They would have to look pretty hard to find someone who wasn't worried or stressed about something. It's just our way of life.