The US Food and Drug Administration (FDA) is to review scientific evidence that claims that mercury in dental fillings is not harmful to patients. In July 2009, FDA had classified amalgam as a moderate-risk item that released levels of mercury not high enough to cause harm. Dental amalgam is dental restorative material used for dental fillings, which contains a mixture of mercury and other metals. However, consumer and dental activists have petitioned about the possible link between mercury in dental amalgam and neurological problems. An advisory panel will meet and discuss a series of technical questions about how exposure to mercury is measured, whether safe levels of exposure have been set correctly and the reliability of studies of mercury on humans. An official from FDA said that they are not modifying its existing guidance that mercury fillings are safe, and this effort is to justify a second look at the evidence.