When he began getting weak, 61-year-old Ronald Beaver figured he might just be feeling his age. Eventually his problem was traced to a serious blood disorder caused by low levels of copper.
"I didn't know what to think," Beaver said of his illness three years ago. "I had no idea. I was just scared to death."
It wasn't until several weeks later -- after the moving company employee from Tamarac, Fla., started getting daily doses of copper -- that Beaver's doctor mentioned that getting too much zinc can trigger loss of copper. The only source of that much zinc they surmised was the tubes of PoliGrip denture cream he had been grossly overusing for a decade.
"The dentures I had then didn't fit that good. They would get loose and I would reapply," he said.
Now Beaver, who said he never fully recovered, and hundreds of other people claiming similar problems are suing consumer products giants Procter & Gamble Co., which makes Fixodent, and GlaxoSmithKline, maker of PoliGrip. At least 25 lawsuits from 11 states have been consolidated for pretrial hearings before a federal judge in Miami, who will decide if they go to trial or not. Another hearing is planned for next month.
The companies say denture cream containing zinc is safe when used as directed. And the Food and Drug Administration, which regulates denture adhesives, has never issued any warnings about the products. Indeed, the amount of zinc found in the recommended application of denture cream is similar to the amount found in a 6-ounce hamburger, and the overwhelming majority of users have no problems. The zinc improves adhesive power.
The lawsuits claim the products are defective, that the companies failed to adequately warn people about the potential dangers and that no corrective steps were taken. The product liability lawsuits are seeking medical expenses and unspecified damages.
While acknowledging the problems are rare, Beaver's attorney, Scott Weinstein, says he expects many more lawsuits to be filed.
The legal action followed a 2008 report in the medical journal Neurology about a possible link between denture cream zinc and nerve damage. Doctors at the University of Texas Southwestern Medical Center in Dallas described four patients who all used excessive amounts of denture cream and had various nerve-related disorders.
The researchers said their report did not prove denture cream caused the problems, but concluded the issue warranted further study. The human body needs both zinc and copper in the proper amounts, and zinc is commonly found in many foods, vitamin supplements and even cold lozenges. Too much zinc, though, can purge the body of copper.
A copper deficiency can cause nerve damage, resulting in symptoms such as weakness and numbness in arms and legs; difficulty walking and loss of balance; and even cognitive or memory impairment, according to the National Institutes of Health.
Dr. Jane Flinn, director of the undergraduate Neuroscience Program at George Mason University in Fairfax, Va., noted that all four patients in the report used excessive amounts of denture cream.
"The take-home message is that zinc deficiency is an important issue, but an excess of zinc is also a problem," said Flinn, who was not involved in the Texas report.
In the four Texas cases -- as well as that of Beaver and other lawsuit plaintiffs -- patients were using far more than the recommended amount of denture cream, perhaps two or three tubes per week. A tube is supposed to last three to 10 weeks, with directions calling for only small dabs of the adhesive to keep dentures in place.
Cincinnati-based Procter & Gamble and Britain's GlaxoSmithKline said in statements to The Associated Press that their denture creams are safe when used properly. On their Internet sites, both have sections devoted to the issue of zinc in their denture creams. This summer, GlaxoSmithKline began including leaflets with PoliGrip about the reports of possible problems from overuse and is adding similar wording to new packages.
"When the product is used as directed, the amount of zinc that might be swallowed is small and is not harmful," said GlaxoSmithKline spokeswoman Malesia Dunn. "Consumers should not use denture adhesive to compensate for a poorly fitting denture."
The Consumer Healthcare Products Association, a nonprofit organization that represents makers of over-the-counter medicines, said the denture creams containing zinc were first approved by the FDA 15 years ago. The leading brands still contain zinc, although there are alternatives available without it.
"Adverse events are very rare," said association spokeswoman Elizabeth Funderburk.
Likewise, the American Dental Association said the link between denture cream use and neurological problems remains unproven, The group urges people with denture difficulties not to overuse the adhesives and see their dentist if they have loose-fitting dentures.