The Sixteenth Conference of the International Society for Environmental Epidemiology (ISEE): Abstracts
Human epidemiological and animal toxicological literature regarding fluoride exposure and osteosarcoma, one of the potential risks of fluoridation, is inconsistent and equivocal. Canine osteosarcoma represents a naturally occurring animal model of this neoplasm. This important potential sentinel can contribute significantly to our understanding of the effects of community fluoridation. In humans and dogs, osteosarcoma is the most common primary malignant tumor of bone. It is the fourth most common cancer in people under 25 years of age and occurs in dogs with an incidence rate of 8 in 100,000, approximately eight times greater than that in humans. Every year, roughly 8000 new cases are identified in dogs.
This study explores the potential association between fluoride exposure and canine osteosarcoma. We conducted a case-control study in which individual dogs were selected from a large client base of a university veterinary teaching hospital with a significant cancer caseload. Two hundred and fifteen cases and an equal number of control dog owners completed a questionnaire in which they identified all residences where the dogs resided as well as home water treatment systems, consumption of bottled water, and use of fluoridated dental hygiene products. Individual residential histories and questionnaire data were linked with water utility data for fluoride, natural and adjusted, and an exposure matrix was created for lifetime estimates of fluoride exposure for both groups of dogs. Multiple logistical regression analysis is currently being performed to estimate risks associated with exposure to fluoridated water and other factors. Physical activity, rapid growth, age at neutering, and exposure to environmental tobacco smoke are being investigated as potential confounders.
This is the first epidemiologic study of the effects of fluoride in pet animals. It also represents one of only a few available case-control studies in any species designed to examine the potential association between exposure to fluoride and osteosarcoma. Canine osteosarcoma has been used as a model for the human counterpart to explore pathogenesis and evaluate treatment. In both species, the etiology remains unknown. If an association between fluoride and canine osteosarcoma is demonstrated, the findings of this study would give additional impetus to further research in humans, due to the pervasive nature of the exposure and potential health implications.