Amalgam (dentistry) can cross the placenta leading to stillbirths and birth defects. A combination of mercury and non-ionizing radiation has been suggested as a factor in the recent increase in reported autism spectrum disorders. It has been reported that there is a positive correlation between the maternal and cord blood mercury levels. Although there is no evidence linking amalgam use and pregnancy damage, it is advisable to delay or avoid dealing with amalgam fillings in pregnant patients. Dentists are urged by some to consider the selection of restorative material more seriously and avoid using amalgam when possible. The dental operating team should
Chemical element or an electrophile; similarly "Nu" denotes a nucleophile. "L" is used to represent a general ligand in inorganic and organometallic chemistry. "M" is also often used in place of a general metal. At least two additional, two-letter generic chemical symbols are also in informal usage, "Ln" for any lanthanide element and "An" for any actinide element. "Rg" was formerly used for any rare gas element, but the group of rare gases has now been renamed noble gases and the symbol "Rg" has now been assigned to the element roentgenium. Isotopes are distinguished by the atomic mass number (total protons and