Opponents are fighting tooth and nail as Health Canada prepares to hear final arguments on restricting mercury fillings.

Caught in the middle is former federal scientist Mark Richardson. His scientific report for Health Canada recommended limits on the widely used, silver-colored mercury amalgam fillings.

Federal health officials have scheduled a final meeting of stakeholders in the battle for mid-February, after which government policy on the fillings is expected.

Richardson's report in December recommended limiting the number of fillings in patients' mouths, to reduce the health risk from exposure to mercury -- a toxic heavy metal with no known safe dose.

mercury vapor from the fillings enters people's bodies every day over the fillings' lifetime.

Richardson recommended toddlers and children be limited to one filling, teenagers to three and adults to four.

In the U.S., the powerful American Dental Association alleges that Richardson "inappropriately used" an ADA-sponsored study of dentists -- exposed to mercury at work -- in recommending limits for the general population.

"We think that his recommendations are not based on sound science," spokesman Chris Martin said from ADA headquarters in Chicago.

Martin said the ADA also fears that if the Canadian government restricts use of the the fillings, it will have repercussions in the U.S.

Richardson says the ADA's allegation reveals its ignorance of the science involved. He noted that the main author on the study he referenced "told me directly that she believed I had properly used that research."

Richardson questioned the scientific credibility and the motives of both the American and Canadian dental associations in responding to his report.

"It is extremely frustrating when mere propaganda is used in an attempt to discredit a reasonably rigorous and peer-reviewed" report, scrutinized by 18 independent experts in the field, he said from Ottawa.

Richardson said the Canadian Dental Association, with virtually no expertise in toxicology or risk assessment, persists in sending factually incorrect and misleading information on mercury fillings to dentists and, through them, their patients.

None of the CDA's dental committee members spearheading the effort to keep the fillings have ever "published one paper on the biological effects of amalgam," says University of Calgary medical researcher and dentist Murray Vimy, who did a search of the scientific literature.

CDA committee member Peter Williams, a dentistry professor at the University of Manitoba, argues that the group draws on outside expertise, in concluding that amalgam's benefits as a tooth repair material outweigh the risks.

Richardson, however, noted that the CDA declined his invitation to provide such expertise or other input in November, 1994 -- more than a year before his Health Canada report was released.

Although the mercury exposure from fillings has yet to be directly linked to any disease, he added, "I view such effects as adverse and to be reduced or avoided, where possible."

Richardson said studies of workers exposed to relatively low levels of mercury clearly show impaired central nervous system functions, including reduced concentration and increased tension.

Calgary Herald January 26, 1996

Also make sure to read these books: Poison in Your Teeth: Mercury Amalgam (Silver) Fillings...Hazardous to Your Health! and Mercury Detoxification by Tom McGuire