The hazards associated with fluoride have been known for many decades. This article was published in 1986 and is just as relevant today.
Heifetz SB, Horowitz HS. Amounts of fluoride in self-administered dental products: safety considerations for children. Pediatrics 1986 Jun; Vol. 77 (6), pp. 876-82
With the increased use of various fluoride preparations for caries prevention, all dental personnel should know their potential toxicity and the margins of safety associated with their use. An understanding of the body’s mechanisms for handling fluoride provides a rational basis for assessing the possible risks of excessive fluoride ingestion. Five to 10 g of sodium fluoride is considered a certainly lethal dose for a 70-kg adult. One quarter of the certainly lethal dose can be ingested without producing serious acute toxicity and is known as the safely tolerated dose. Comparisons of certainly lethal and safely tolerated doses for commonly used fluoride agents and procedures show that they can be applied with little or no risk of adverse acute effects, as long as they are used judiciously. If their use is abused, there is a risk of illness or even death. If amounts of fluoride close to the certainly lethal dose are ingested, the speed of initiating proper treatment is critical for survival. Vomiting should be induced, if it is not spontaneous; fluoride-binding liquids, such as milk or liquid or gel antacids, administered; and the patient taken to the nearest hospital for emergency care. Frequent ingestion of low but excessive quantities of fluoride during the period of tooth formation can lead to dental fluorosis. Particular concern is warranted for the ingestion of fluoride-containing toothpastes by young children and the inappropriate use of dietary fluoride supplements in communities with sufficient fluoride already present in drinking water.
Choubisa, S. Fluorotoxicosis in Diverse Species of Domestic Animals Inhabiting Areas with High Fluoride in Drinking Water of Rajasthan, India. Proceedings of the National Academy of Sciences, India Section B; September 2013, Vol. 83 Issue: 3 p317-321
Chronic fluorotoxicosis in the form of dental and skeletal fluorosis was observed in 443 immature and 2,155 mature domestic animals inhabiting tribal rural areas of southern Rajasthan, India. Their drinking water contained fluoride in the range between 3.1 and 6.1 ppm. These animals included cattle (Bos taurus), buffaloes (Bubalus bubalis), horse (Equus caballus), donkeys (Equus asinus), dromedary camels (Camelus dromedarius), sheep (Ovis aries) and goats (Capra hircus). Of these immature and mature animals 172 (38.8 %) and 826 (38.3 %) showed evidence of dental fluorosis with varying grades, respectively. Their incisor teeth were bilaterally and vertically or horizontally brown to deep yellowish in colour. Also present, as indication of more severe dental fluorosis, were irregular wearing and excessive abrasions of teeth, deep yellowish discoloration of exposed cementum and/or remaining enamel surface and pronounced loss of teeth supporting bone with recession of gingiva. On clinical examination 12.1 % immature and 28.4 % mature animals revealed periosteal exostoses in mandibular regions, ribs, metacarpus and metatarsus, intermittent lameness, hoop deformities and stiffness of tendons in the legs as signs of severe skeletal fluorosis. In the fluorosed animals other signs of chronic fluoride intoxication as colic, intermittent diarrhoea, excessive urination, irregular reproductive cycles, repeated abortions, sterility and still birth were seen. No significant variation in prevalence of dental fluorosis was found between mature and immature animals. However, mature animals showed relatively higher (28.4 %) prevalence of skeletal fluorosis as compared to their counterparts (12.1 %). Among these animal species, buffaloes revealed the maximum prevalence of dental (96.8 %) and skeletal (66.9 %) fluorosis and minimum of 17.02 and 8.7 %, respectively, was observed in goats. However, prevalence and severity of osteo-dental fluorosis greatly varied from species to species and between grass-eaters or grazers (cattle, buffaloes and equines) and plant-eaters or browsers (camels and flocks). Causes for variation in prevalence and severity of fluoride toxicity in different species and between animals of different feeding habits are discussed.