1. There is a strong selection bias among the people I see, biased towards people who are much more impaired. That said, many of them had a pattern of spending

1. There is a strong selection bias among the people I see, biased towards people who are much more impaired. That said, many of them had a pattern of spending more time/energy on their addiction causing themselves lots of problems before they sought help. It is true that for some substances there are many people who use recreationally without major problems, and I don't see them (and don't need to see them) for treatment. I have never seen a casual user of intravenous heroin, but perhaps there are some. 2. Difficulty establishing purity is one issue, but the overdoses happen just as often with prescription pain pills with predictable strength. Many people will continue to chase a bigger high and get in trouble that way. Other people (as described in the article) will stop using for a time and lose their tolerance, then assume that a dose that was previously safe is OK. Then they stop breathing. Methadone clinics generally provide the same steady dose, which avoids this problem.