Dog Food Comparison Shows High Fluoride Levels
June 26, 2009

Dog Food Comparison Shows High Fluoride Levels: Fluoride and Osteosarcoma

Fluoride in naturally or artificially fluoridated water has been linked with osteosarcoma in young boys and teenagers less than 20 years of age (NRC 2006). Osteosarcoma accounts for about 3% of all childhood cancers, and occurs with an incidence of 0.3 cases per 100,000, more commonly in boys than in girls (NRC 2006). While rare, this cancer is deadly – the 5-year mortality rate is around 50%, and nearly all survivors have limbs amputated, usually legs. Similar to young boys, dogs are well known to be at risk from osteosarcoma (Ru 1998).

Osteosarcoma is the most common primary bone tumor in dogs; it is estimated to occur in over 8,000 dogs each year in the U.S., primarily in larger breeds (Chun 2003; Dernell 2001; Priester 1980; Withrow 1991). According to a recent expert review, the actual incidence is probably higher, since not all cases are confirmed and registered (Mueller 2007). Large dogs with fast growing bones are especially at risk. Only 5% of all osteosarcomas develop in dogs weighing less than 30 pounds and giant dogs generally develop osteosarcoma at a younger age compared to smaller-sized dogs and (Cooley 1997; Misdorp 1979).

Scientists are still trying to understand the full spectrum of causes for canine osteosarcoma. Mutagenic effects of radiation, multiple minor traumas, metallic implants, and genetic predisposition have been suggested as possible risk factors for osteosarcoma (Mueller 2007). Yet, one of the very plausible scientific links points to fluoride as a possible causative agent for osteosarcoma in both large dogs and young boys.

Three factors likely contribute to fluoride's ability to produce bone cancer: fluoride accumulates in the bones (NRC 2006); fluoride is an active mitogen (a substance that stimulates cell division) that causes a rapid proliferation of bone-building cells known as osteoblasts (Gruber 1991; Kleerekoper 1996; Whitford 1996); fluoride's cancer-promoting effects are especially significant in young boys whose bones grow more rapidly than for any other group (Bassin 2006).

The science supporting the link between fluoride and bone cancer in boys is compelling, and includes 3 focused epidemiological studies (Bassin 2006; Cohn 1992; DHHS 1991), 2 long-term animal studies (Maurer 1991; Maurer 1993; NTP 1990), a wealth of mechanistic information on the effect of fluoride on the developing bone (reviewed in NRC 2006), and a new study published in 2009 that detected higher fluoride levels in osteosarcoma patients compared to 2 other groups: patients with bone-forming tumors other than osteosarcoma, and people serving as "controls" in the study who were experiencing musculo-skeletal pain but did not have tumors (Sandhu 2009).

The incidence of many cancers in dogs is higher than in humans and the progression is usually faster (Mueller 2007). A dog's diet, especially during the early growth spurt, is a likely contributor to their overall cancer risk. While human infants and young children can eat a variety of foods, puppies and adult dogs eat the same dry dog food, often high in fluoride, every day. This high level of fluoride exposure may well be a contributing factor to osteosarcoma in dogs and an avoidable health risk that dog owners can control.