In the 1990s, several governments evaluated the effects of dental amalgam and concluded that the most likely health effects would be due to hypersensitivity or allergy. Germany, Austria, and Canada recommended against placing amalgam in certain individuals such as pregnant women, children, those with renal dysfunction, and those with an allergy to metals. In 2004, the Life Sciences Research Officeanalyzed studies related to dental amalgam published after 1996 and concluded that mean urinary mercury concentration (μg of Hg/L in urine, HgU) was the most reliable estimate of mercury exposure. It found that those with dental amalgam were unlikely to reach the levels where adverse effects are seen from occupational exposure (35 μg HgU). Some 95% of study participants had μg HgU below 4-5. Chewing gum, particularly for nicotine, along with more amalgam, seemed to pose the greatest risk of increasing exposure. One gum-chewer had 24.8 μg HgU. Studies have shown that the amount of mercury released during normal chewing is extremely low. It concluded that there was not enough evidence to support or refute many of the other claims such as increased risk of autoimmune disorders, but stated that the broad and nonspecific illness attributed to dental amalgam is not supported by the data.Mutter in Germany, however, concludes that “removal of dental amalgam leads to permanent improvement of various chronic complaints in a relevant number of patients in various trials.”