In North America, in the year 1997 there were 800,000 people who underwent the therapy, and 880,000 people in 1998 reported. Since the year 2000 onwards there have been more than one million people who underwent this treatment yearly. There are many quarters who claimed that chelation therapy has no study. It is true because they refer to double blind control study. However there were enough evidence to support the effectiveness of the therapy.