The American Dental Association, Georgia Dental Association and drug firms American Home Products Corp., now known as Wyeth, GlaxoSmithKline Plc., Johnson & Johnson and Armour Pharmaceutical were accused of, among other things, negligence in 11 lawsuits filed in an Atlanta court.

Georgia Power, a unit of utility firm Southern Co., was also listed as a defendant in the suits for allegedly releasing harmful mercury-containing emissions into the environment.

The families are seeking unspecified damages on behalf of their children. A similar lawsuit was filed against the companies and dental groups in the same court late on Tuesday. Six other suits are expected later this week.

Shawn Khorrami, an attorney for the families, said the dental groups had misled consumers by not telling them that amalgam fillings contained mercury and could, when implanted in women's mouths, expose fetuses and nursing infants to toxic levels of mercury.

The drug companies are being sued because they failed to warn parents that children receiving vaccines containing the mercury-based preservative thimerosal were at higher risk for mercury poisoning, according to the suits.

Some scientists have linked mercury to autism. Amalgam fillings typically contain about 50% mercury.

In a statement released to Reuters, the American Dental Association (ADA), which claims more than 141,000 members across the country, described the lawsuits as an "egregious" abuse of the legal system and said the claims had no merit.

"Actions like these mislead vulnerable people, using information with no scientific basis to give false hope to those with chronic, often incurable illnesses," it said.

Johnson & Johnson and Georgia Power said they had not yet had a chance to review the complaints in the lawsuits.

Earlier this year, the FDA reported that US Public Health Service scientists had concluded that recently collected data did not support claims that people with amalgam fillings experienced problems, other than rare allergic or hypersensitivity reactions.