As some of you may know, a recent study on fluoride and elk has been attracting quite a bit of media attention recently. The study, published in the journal Ecosystems by scientists at Montana State University, looked at the effects of excess fluoride on the lifespan of elk in Yellowstone National Park.
As described by the Associated Press (Feb 13, 2004):
“For some elk in Yellowstone National Park, exposure to excess fluoride while they are young can actually take years off their lives, a researcher says.
Bob Garrott, a professor in the ecology department at Montana State University in Bozeman, said that elk that stay in the west-central portion of the park – the area that’s home to assorted hot pools and geysers – seem to die at least five years earlier than elk that live elsewhere in the park.
The reason, he said Thursday, is fluoride – specifically, too much of it.
While a little fluoride is good for teeth, exposure to too much of it – particularly at a young age when permanent teeth are forming – affects the enamel of the elks’ teeth and makes them wear out faster, Garrott said. That accelerates the aging process and may even leave more adult elk susceptible to predation, especially by wolves, he said.”
When I first read the press release discussing this study, I couldn’t help but think of the recent work from Drs Horst and Uwe Kierdorf of Germany.
Over the past 15 years, Dr. Horst and Uwe Kierdorf have been conducting extremely interesting research on fluoride pollution’s impact on deer (see list of studies below).
The Kierdorfs’ research on fluoride falls into two general categories.
On the one hand, the Kierdorfs have used deer as biomarkers with which to gauge the extent and distribution of industrial fluoride pollution – as a function of both geography and time. Using the severity of dental fluorosis or the accumulation of fluoride in deer’s teeth, antlers and bone, the Kierdorfs have been able to elucidate areas of intense fluoride pollution (e.g. The Czech-German border downwind of the most notorious coal-burning region in Europe), and also elucidate historic trends in fluoride pollution (which makes for some very interesting reading).
The other focus of the Kierdorfs’ work has been to study how the fluoride pollution is actually impacting the deer.
Not surprisingly, the Kierdorfs’ findings concerning the deer’s teeth are very much consistent with the recent findings from Montana.
In 1996, the Kierdorfs described the teeth of deer downwind of the Czech coal industry, noting “a reduction in height or complete loss of the enamel ridges”, “diminished enamel hardness”, “a moderately to grossly increased wear of the cheek teeth [which] eventually led to severe dental disfigurement and loss of a functional tooth shape,” while “In the two most severe cases, periodontal breakdown was so extensive that individual teeth had been lost.”
And, with great relevance to the recent Montana study, the Kierdorfs concluded that: “In a free-ranging ruminant like the red deer, loss of a functional tooth shape as was demonstrated in our material will inevitably lead to a more or less intense fitness reduction.” (An intense fitness reduction, caused by loss of tooth function, is believed to be the key factor in the Yellowstone Elk’s short lifespan.)
What about the Bones?
Of potentially greater interest, however, are the Kierdorfs’ findings on how fluoride impacts the deer’s bone, particularly the antlers. (Unfortunately, the recent Montana study does not appear to have examined this aspect of the problem.)
In 2 studies from 1997 and 2000, the Kierdorfs examined the quality of antler bone in deer downwind of fluoride polluting industries. In both studies, the Kierdorfs found that fluoride reduced the mineral content and density of the antler bone. The Kierdorfs concluded that antler bone – because of its rapid rate of mineralization (it is formed in less than a year) – is particularly susceptible to fluoride induced toxicity. To quote:
“It is concluded that increased fluoride exposure of deer leads to reduced mineral content and mineral density of antler bone and that it is the rapidity of their growth and mineralization that makes antlers especially susceptible to fluoride action” (Kierdorf 1997).
There are many interesting things to say about the potential relevance of the Kierdorfs’ bone findings to humans (and we will discuss these in a follow-up bulletin), however, for now, we’ll just focus on the implications of their findings to deer.
After finding that fluoride reduced the mineral content and density of antlers, the Kierdorfs noted:
“It is likely that the bone changes induced by fluoride will lead to an impaired biomechanical competence of antlers… We, therefore, would expect to find an increased incidence of antler breakage in such populations. The only other study on the effect of pollutants on antler quality so far has been the one by Jop (1979) on roe deer from a forest region in South Poland. He found that between 1922 and 1973 average antler weight in the deer had declined by 32% and argued that this was due to contamination from a large iron and steel works opened in the vicinity of the forest in 1957. As was later shown by Grodzinska et al. (1983), this forest area is in fact exposed to an increased deposition of various pollutants, including a high fluoride fallout” (Kierdorf 1997).
The Kierdorfs’ suggestion that fluoride, by reducing mineral content and density, could cause an increase in antler fracture, was a timely one.
Fluoride & Antler Fractures in Colorado
For, at about the same time that the Kierdorfs were conducting their research, observations began to arise near a US military base in Colorado Springs, Colorado, that deer in the vicinity of the base were experiencing an unusual number of antler fractures.
When a group of scientists from Virginia Tech University examined the deer, they found that – in addition to a high rate of tooth lesions – the deer had a remarkably high level of fluoride in their teeth and bones. The researchers noted that the “Fluoride content of bone and tooth tissues were considerably greater than those of deer species from reference sites in other areas where fluoride contamination was a problem.” See: http://www.cnr.vt.edu/fisheries/scanlon.htm.
With this finding in hand, the scientists began a project to determine the relationship between the antlers’ strength and fluoride content. However, as I have recently learned from some faculty at Virginia Tech, this project is no longer being conducted, as the lead scientist, Patrick F. Scanlon, passed away in March of 2003.
Other animal studies – including a comprehensive series of rat and rabbit studies from the 1990s (Turner et al) – have of course repeatedly found that fluoride reduces bone strength . As Dr. Charles Turner, the Director of Orthopedic Research at the University of Indiana, wrote in 1996:
“[O]ne cannot help but be alarmed by the negative effects of fluoride on bone strength consistently demonstrated in animal models… [M]any fluoride treatment regimens have been studied in animals, and I know of only two animal studies that have shown fluoride to increase bone strength… In all other studies, fluoride has either had no effect on bone strength or significantly decreased it.”
Hence, when considering the findings of the Kierdorfs, and when considering the multiple animal studies reporting reduced bone strength, and the larger body of research on livestock fluorosis, it will be interesting to see if the Montana scientists expand their focus to include an examination of the elk’s antlers and bones. For, as common sense alone should indicate, if fluoride is causing the deer’s teeth to erode and fall out, it is probable that bone damage – not to mention some soft tissue damage – is occurring as well. It will be interesting to gauge if, and to what extent, these non-tooth factors are contributing to the early mortality.
Bibliography of the Kierdorfs’ research:
Kierdorf U, Kierdorf H. (2003). Temporal variation of fluoride concentration in antlers of roe deer (Capreolus capreolus) living in an area exposed to emissions from iron and steel industry, 1948-2000. Chemosphere 52:1677-81.
Kierdorf U, Kierdorf H. (2002). Assessing regional variation of environmental fluoride concentrations in western Germany by analysis of antler fluoride content in roe deer (Capreolus capreolus). Archives of Environmental Contamination and Toxicology 42: 99-104.
Kierdorf U, Kierdorf H. (2001). Fluoride concentrations in antler bone of roe deer (Capreolus capreolus) indicate decreasing fluoride pollution in an industrialized area of western Germany. Environmental Toxicology and Chemistry 20: 1507-1510.
Kierdorf H, Kierdorf U, Richards A, Sedlacek F. (2000). Disturbed enamel formation in wild boars (Sus scrofa) from fluoride polluted areas in Central Europe. Anatomical Record 259: 12-24.
Kierdorf U, Kierdorf H. (2000). The fluoride content of antlers as an indicator of fluoride exposure in red deer (Cervus elaphus): A historical biomonitoring study. Archives of Environmental Contamination and Toxicology 38: 121-127.
Kierdorf U, Kierdorf H. (2000). Roe deer antlers as monitoring units for assessing temporal changes in environmental pollution by fluoride and lead in a German forest area over a 67-year period. Archives of Environmental Contamination and Toxicology 39: 1-6.
Kierdorf U, Kierdorf H. (2000). Temporal and geographical variation in skeletal fluoride content of roe deer (Capreolus capreolus) from industrialized areas in Germany. Comparative Biochemistry and Physiology Part C 126: 61-68.
Kierdorf U, Kierdorf H, & Boyde A. (2000). Structure and mineralisation density of antler and pedicle bone in red deer (Cervus elaphus .) exposed to different levels of environmental fluoride: a quantitative backscattered electron imaging study. Journal of Anatomy 196: 71-83.
Kierdorf H, Kierdorf H, Sedlacek F. (1999). Monitoring regional fluoride pollution in the Saxonian Ore mountains (Germany) using the biomarker dental fluorosis in roe deer (Capreolus capreolus L.) The Science of the Total Environment 232: 159-168.
Kierdorf U, Richards A, Sedlacek F, Kierdorf H. (1997). Fluoride content and mineralization of red deer (Cervus elaphus ) antlers and pedicles from fluoride polluted and uncontaminated regions. Archives of Environmental Contamination and Toxicology 32: 222-227.
Kierdorf H, et al. (1996). Mandibular bone fluoride levels and occurrence of fluoride induced dental lesions in populations of wild deer (Cervus elaphus) from central Europe. Environmental Pollution 93: 75-81.
Kierdorf U, Kierdorf H, Sedlacek F, Fejerskov O. (1996). Structural changes in fluorosed dental enamel of red deer (Cervus elaphus L.) from a region with severe environmental pollution by fluorides. Journal of Anatomy 188: 183-195.