Joel R. Rhine, attorney with Lea, Rhine, Rosbrugh & Chleborowicz, PLLC, says the effects of zinc toxicity can be quite severe. Symptoms of hypercupremia (copper deficiency) linked to zinc toxicity include abdominal pain, nausea, vomiting, diarrhea, dizziness, lethargy and anemia.
In the opening to the Neurology study, researchers note that copper deficiency (hypocupremia) is linked to hyperzincemia (chronic excess zinc intake, also called zinc toxicity) but that the source of hyperzincemia is often difficult to determine. They write that the patients identified in their study chronically used a lot of denture cream and the denture cream was the only plausible source of their zinc toxicity.
Rhine says that the denture cream usage presented in the Neurology article is widespread. He states, "The denture cream manufacturers' usage instructions are scant, at best, and filling the dentures with a line of cream is the understood manner of application. Now, our clients have learned that this is potentially harmful but no contrary instructions were provided."
Researchers in the Neurology study note that the use of a minimum of two standard 68 g tubes of denture cream a week would lead to exposure to a minimum of 330 mg of zinc per day. They further write that they can then assume that ingestion of the zinc is well above recommended daily allowances, which are 8 mg for women and 11 mg for men. Furthermore, they believe that the daily intake of zinc for the study's subjects may have exceeded the daily tolerable upper level intake of 40 mg, a level established by the National Academy of Sciences.
According to Rhine, it is critical that people who believe they have suffered zinc toxicity see their doctor immediately and have simple blood tests done to determine if they do have hyperzincemia or hypocupremia.
"As soon as they stop their typical usage of denture cream, they need to have the tests run immediately," Rhine says. "It should be done as soon as possible. Your doctor may provide you with copper supplements to counteract the decreased copper in your system, so this imbalance [of copper] won't show up on subsequent blood tests because the supplements will counteract the imbalance. We advise our clients that they absolutely should not stop their medical treatment, but they should get the tests run at the same time. These tests basically preserve the evidence, which helps them in their lawsuit, but more importantly, assists the physicians in properly diagnosing what is causing these abnormalities."
Rhine notes that some of the blood tests include:
- A Zinc RBC
- A Copper RBC
- A spot urine test for Zinc
- A spot urine test for Copper
- A blood test for ceruloplasmin
Unfortunately, people may have been suffering zinc toxicity for a while and not ever linked it to their denture cream.
"People have not really thought about the zinc intake through denture cream and that makes sense because it is not of the type of product that requires significant amounts of mandated warnings," Rhine says. We believe that they [denture cream makers] should have warned users about the possibilities of the zinc level and that excess usage in certain expected ways would be harmful. There is no proper demonstration and description of safe use of the [denture cream] on the product's labels. That is simply unacceptable."
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"The number one thing that we are telling our clients is to follow the advice of their physician," Rhine says. "Neurologists have had difficulty diagnosing this in the past, so at least mention it to them [if you have used denture cream] and let them conduct an investigation and make an independent assessment as to if this could be the root of neurological problems."
According to Rhine, the main denture cream brands involved in the lawsuits are Fixodent, PoliGrip and Super PoliGrip. Fixodent is made by Proctor & Gamble, while the PoliGrip products are made by GlaxoSmithKline.