Fluoride Action Network

Interview with EPA’s Dr. William Marcus on NTP’s Fluoride/Cancer Study

Fluoride Action Network

The following is an interview with Dr. William Marcus, Senior Science Advisor in EPA’s Office of Drinking Water, concerning the National Toxicology Program’s animal study on fluoride & cancer. The interview is with Dr. Gary Null, and was aired on Null’s radio show (program #310) on March 10, 1995. 

Marcus: When I got a hold of the contractor report and reviewed it very carefully, not only was it reporting cancers in the animals, [it was reporting] osteosarcomas which bothered me a lot because I’ve been trying to produce osteosarcomas in animals for almost 20 years and the only luck I ever had was with an experiment in dogs and monkeys, and the osteosarcomas took nearly the lifetime of the animals, and we were using radium which specifically produces that in bones. And here we have a compound commonly available – fluoride – that did it in rats in two years or less. That was upsetting to begin with. Secondarily…in that same study, there were cancers of the liver that are very rare according to the board certified veterinary pathologist at the contractor, Battelle. And those really were very upsetting because they were hepatocholangiocarcinoma, a very rare, rare, liver cancer… Something similar to that occurred with vinyl chloride in a far less well conducted study and it was determined that it was carcinogenic, highly carcinogenic. And then there were several other kinds of cancers found in the jaw and other places and I felt at the time that the report was very, very interesting. It showed that the levels of the fluoride that caused the cancers in the animals were actually lower than those levels seen in people who are ingesting lower amounts but for longer periods of time and that was very very worrisome. It meant that the general population could be exposed to fluoride known to cause cancer in animals and have levels near the cancer being produced in the bones.

Gary Null: And what did you do and what happened?

Marcus: Well I went to a meeting that was held in Research Triangle Park in April 1990, the latter part of April, in which the NTP was presenting their review of the study. And I went with several colleagues of mine, one of whom was a board certified veterinary pathologist who had originally reported hepatocholangiocarcinoma as a separate entity in rats and mice. I asked him if he would have an opportunity to look at the slides to see if that  really was a tumor or the pathologist at Battelle had made an error and he told me after looking at the slide that in fact it was correct. And at the meeting every one of the cancers that was reported by the contractor had been down-graded by the NTP.

Now I’ve been in the toxicology business looking at studies of this nature for nearly 25 years and I’ve never seen that; never ever seen where every single endpoint that was a cancer endpoint had been down-graded. I’d seen one or two endpoints argued over, usually on a definition [of] what is a cancer in that particular tissue. But I’ve never seen every one of them down-graded. I found that very suspicious and I went to see an investigator in the Congress at the suggestion of my friend Bob Carton. And this gentleman and his staff investigated very thoroughly and found out that the scientists at the NTP down at Research Triangle Park had been coerced to change their findings.

Gary Null: Coerced by whom?

Marcus: I never really got that. But the only people that can coerce them were their supervisors.

Gary Null: Why would they want to coerce them? What were they trying, who or what were they trying to protect?

Marcus: Well as you well know fluoride is still recommended as a treatment for prevention of dental caries, tooth decay, and has been touted as such by the Public Health Service since 1953-54 and they ha[ve] a reputation to protect. It wouldn’t do for them to have been making this strong recommendation over the years and now to find out that they have been exposing the general public to a material known, now known, to be potentially carcinogenic in humans. And there have been other studies…”


NOTE: Due to his criticisms of the tumor downgradings, Dr. Marcus was fired by the EPA. The US Secretary of Labor, Robert Reich, later ruled that EPA fired Marcus out of “retaliation” for Marcus’ stance on fluoride, and ordered EPA to reinstate Marcus with full back pay and compensation. To learn more about EPA’s firing of Marcus, see: