USA regulator the Food and Drugs Administration (FDA) has been forced to revise information about dental amalgam on its website.

The move follows settlement of a lawsuit filed against the federal agency by Moms Against Mercury, a group opposed to the use of dental amalgam fillings.

The "reassuring" language the FDA had used has been substituted with the warning: "dental amalgams contain mercury, which may have neurotoxic effects on the nervous system of developing children and foetuses".

It also says that mercury vapour is released when these fillings are places or removed and during the chewing of food.

The FDA agree to set the definite deadline of 28 July 2009 for the reclassification process for dental amalgam, which began in 2002.

The agency is under pressure to call for restrictions in the use of amalgam in the sensitive subpopulation (e.g. children under six years old, pregnant and lactating women, and hypersensitive or immunocompromised individuals) but the American Dental Association is opposed to any reclassification because, it argues, such action is not supported by best scientific studies published on this topic.

In the wake of ensuing media storm in the USA and the UK over the alleged "hidden danger of mercury" in amalgam fillings, the BDA and the Department of Health reiteraited their current advice on adopting the precautionary principal during pregnancy.