Dental amalgam controversy an increasing number of studies with larger sample sizes are being conducted. Those who are not opposed to amalgam claim that, aside from rare and localized tissue irritation, recent evidence-based research has continued to demonstrate no ill effects from the minute amounts of mercury exposure from amalgam fillings. A 2004 systematic review conducted by the Life Sciences Research Office, whose clients include the FDA and NIH, concluded that, "the current data are insufficient to support an association between mercury release from dental amalgam and the various complaints that have been attributed to this restoration material." A systematic review in 2009
Chemical element whole number. For example, the relative atomic mass of chlorine is 35.453 u, which differs greatly from a whole number as it is an average of about 76% chlorine-35 and 24% chlorine-37. Whenever a relative atomic mass value differs by more than 1% from a whole number, it is due to this averaging effect, as significant amounts of more than one isotope are naturally present in a sample of that element. Chemists and nuclear scientists have different definitions of a "pure element". In chemistry, a pure element means a substance whose atoms all (or in practice almost all) have the