Keyword search

 The negative effects of fluoride on our environment

The following links lead to evidence that fluoride damages freshwater life.

 Patterson, H. J.  Fluoride and the Environment LINK

This u-Tube video explains how salmon were very cautious of passing up a fishladder on the River Columbia in North-western America when there was a concentration of 0.3 - 0.5 ppm fluoride in the water.  The film-maker refers to Damkaer & Dey’s research.

Damkaer, D. M., and D. B. Dey (1989). Effects of fluoride on fish passage.   LINK

This Conference paper discusses the researchers’ observations of disturbed Chinook and Coho salmon passage up the Columbia River in North West USA between 1979 and 1989.  Fluoride levels were at 0.3 – 0.5ppm between 1979 and 1982.  In 1983, the nearby aluminum smelter stopped putting their Haz. Waste into the River.  From that year, the migration of salmon resumed up the river.  The mechanism whereby the fish sensed that there was an unacceptable concentration of fluoride in the river is not explained.

Foulkes, R.C. and A. C. Anderson. (1994) Impact of Artificial Fluoridation on Salmon Species in the Northwest USA and British Columbia, Canada.  Fluoride Vol.27 No.4 220-226 1994.   LINK

This Conference paper was presented at the XXth Conference of the International Society for Fluoride, Research, Beijing, China, September 1994.  It reviews the existing literature relating to the effect of fluoride on freshwater fish.

A review of the literature suggests that concentrations of fluoride above 0.2 mg/L have lethal (LC50) effects on and inhibit migration of "endangered" salmon species whose stocks are now in serious decline in the US Northwest and British Columbia.

The most disturbing issue highlighted by the researchers was that the staple food of salmonids (the water flea) was killed at levels of fluoride above 0.1ppm.

Bibliography (from the Foulkes and Anderson review).  Not all sources can be viewed via the Internet.

  1. Water Quality 1972. Environmental Protection Agency (USEPA) Committee on Water Quality Criteria, Environmental Studies Board, 1973.  (Superseded by Water Quality Standards Handbook, Second Edition (USEPA, 1994).  LINK
  2. Recommended BC Health Branch Water Quality Standards. British Columbia Department of Health Services and Hospital Insurance. 1969.
  3. Letter from J O'Riordan, Assistant Deputy Minister, British Columbia Ministry of Environment, 22 July 1993.
  4. Letter from Ray Hennekey, Washington State Department of Ecology. February 23, 1993.
  5. Groth III E. An evaluation of the potential for ecological damage by chronic low-level environmental pollution by fluoride. Fluoride 6 (4) 224-240 1975.
  6. Warrington PD. Ambient Water Quality Criteria for Fluoride. Technical Appendix. British Columbia Ministry Of Environment. 1990. LINK
  7. Angelovic JW, Sigler WF, Neuhold JM. Temperature and fluorosis in Rainbow trout. Journal. Water Pollution Control Federation 33 371-381 1961.
  8. Neuhold JM, Sigler WF. Effects of sodium fluoride on carp and Rainbow trout. Transactions. American Fisheries Society 89 358-370 1960.
  9. Pimental R. Bulkley RB. Influence of-water hardness on fluoride toxicity to Rainbow trout. Environmental Toxicology and Chemistry 2 381-386 1983.
  10. Damkaer DM, Dey DB. Evidence for fluoride effects on salmon passage at John Day Dam, Columbia River, 1982-1986. North American Journal of Fisheries Management 9 154-162 1989.
  11. EIlis MM, Westfall BA, Ellis MD. Determination of Water Quality Research Report 9. Fish and Wildlife Service, Department of Interior, Washington DC 1938 pp 81-82.
  12. Hemens J: Warvick RJ, Oleff WD. Effect of extended exposure to low fluoride concentration on estuarine fish and crustacea. Progress in water Technology 7 579-585 1975.
  13. Ishio S, Makagawa H (1971). Cited in: Rose D. Marier J. Environmental Fluoride 1977. National Research Council of Canada, Ottawa 1977 p 30.
  14. Dave G. Effects of fluoride on growth reproduction and survival in Daphnia magna. Comparative Biochemistry and Physiology 78c (2) 425-431 1984.
  15. US Court Of Appeals, Ninth Circuit (Pocatello, Idaho) No 17059 (1961): Food and Machinery and Chemical Corporation and J R Simplot Co. vs W S and Ray Meader. Exhibit (Table 1) August 25 1961.
  16. Carpenter R. Factors controlling the marine geochemistry of fluorine. Geochemical et Cosmochimica Acta 33 1153-1167 1969.
  17. Masuda TT. Persistence of fluoride from organic origins in waste waters. Developments in Industrial Microbiology 5 53-70 1964.
  18. Singer L. Armstrong WD. Fluoride in treated sewage and in rain and snow. Archives of Environmental Health 32 21-23 1977,
  19. Bahls LL. Diatom community response to primary waste water effluent Journal Water Pollution Control Federation 45 134-144 1973.
  20. Miller GW. Effect of fluoride on higher plants. Fluoride 26 (1) 3-22 1993. (Table 1, p 5)
  21. Fluoridation Census 1985US Department of Health and Human Services. Public Health Service, 1988.


The level of fluoride in sewage effluent which has a
negative effect on river life



Where the concentration of fluoride in treated water is 1ppm, this results in 0.5ppm fluoride ending up in the river at the sewage outfall.  A further 0.4-0.5ppm can be found in sewage sludge.   An analysis of the sewage effluent 1k downstream of Finham Sewage Works in Coventry gave a result of 0.5ppm at a time when the concentration of fluoride in Coventry's water was 1ppm.

The writer of the letter is correct in saying that the safe no effect concentration has been estimated at 5mg/l.  However, this is not the same thing as deterring fish from inhabiting river water which contains 0.5ppm.

The IPCS Inchem site ( contains the relevant reciew of the evidence : .  Here is an extract from Chapter 1.8 which relates to freshwater life: 

1.8 Effects on other organisms in the laboratory and field

Fluoride did not affect growth or chemical oxygen demand degrading capacity of activated sludge at concentrations of 100 mg/litre. The EC50 for inhibition of bacterial nitrification was 1218 mg fluoride/litre. Ninety-six-hour EC50s, based on growth, for freshwater and marine algae were 123 and 81 mg fluoride/litre, respectively.

Forty-eight-hour LC50s for aquatic invertebrates range from 53 to 304 mg/litre. The most sensitive freshwater invertebrates were the fingernail clam (Musculium transversum), with statistically significant mortality (50%) observed at a concentration of 2.8 mg fluoride/litre in an 8-week flow-through experiment, and several net-spinning caddisfly species (freshwater; family: Hydropsychidae), with "safe concentrations" (8760-h EC0.01s) ranging from 0.2 to 1.2 mg fluoride/litre. The brine shrimp (Artemia salina) was the most sensitive marine species tested. In a 12-day static renewal test, statistically significant growth impairment occurred at 5.0 mg fluoride/litre.

Ninety-six-hour LC50s for freshwater fish range from 51 mg/litre (rainbow trout, Oncorhynchus mykiss) to 460 mg/litre (threespine stickleback, Gasterosteus aculeatus). All of the acute toxicity tests (96 h) on marine fish gave results greater than 100 mg/litre. Inorganic fluoride toxicity to freshwater fish appears to be negatively correlated with water hardness (calcium carbonate) and positively correlated with temperature. The symptoms of acute fluoride intoxication include lethargy, violent and erratic movement and death. Twenty-day LC50s for rainbow trout ranged from 2.7 to 4.7 mg fluoride/litre in static renewal tests. "Safe concentrations" (infinite hours LC0.01s) have been estimated for rainbow trout and brown trout (Salmo trutta) at 5.1 and 7.5 mg fluoride/litre, respectively. At concentrations of >3.2 (effluent) or >3.6 (sodium fluoride) mg fluoride/litre, the hatching of catla (Catla catla) fish eggs was delayed by 1–2 h.

Behavioural experiments on adult Pacific salmon (Oncorhynchus sp.) in soft-water rivers indicate that changes in water chemistry resulting from an increase in the fluoride concentration to 0.5 mg/litre can adversely affect migration; migrating salmon are extremely sensitive to changes in the water chemistry of their river of origin. In laboratory studies, fluoride seems to be toxic for microbial processes at concentrations found in moderately fluoride polluted soils; similarly, in the field, accumulation of organic matter in the vicinity of smelters has been attributed to severe inhibition of microbial activity by fluoride.  [My emphasis added]

The remainder of the sub-chapter is as follows:

Signs of inorganic fluoride phytotoxicity (fluorosis), such as chlorosis, necrosis and decreased growth rates, are most likely to occur in the young, expanding tissues of broadleaf plants and elongating needles of conifers. The induction of fluorosis has been clearly demonstrated in laboratory, greenhouse and controlled field plot experiments. A large number of the papers published on fluoride toxicity to plants concern glasshouse fumigation with hydrogen fluoride. Foliar necrosis was first observed on grapevines (Vitis vinifera) exposed to 0.17 and 0.27 µg/m3 after 99 and 83 days, respectively. The lowest-observed-effect level for leaf necrosis (65% of leaves) in the snow princess gladiolus (Gladiolus grandiflorus) was 0.35 µg fluoride/m3. Airborne fluoride can also affect plant disease development, although the type and magnitude of the effects are dependent on the specific plant–pathogen combination.

Several short-term solution culture studies have identified a toxic threshold for fluoride ion activity ranging from approximately 50 to 2000 µmol fluoride/litre. Toxicity is specific not only to plant species, but also to ionic species of fluoride; some aluminium fluoride complexes present in solution culture may be toxic at activities of 22–357 µmol fluoride/litre, whereas hydrogen fluoride is toxic at activities of 71–137 µmol fluoride/litre. A few studies have been carried out in which the fluoride exposures have been via the soil. The type of soil can greatly affect the uptake and potential toxicity of fluorides.

In birds, the 24-h LD50 was 50 mg/kg body weight for 1-day-old European starling (Sturnus vulgaris) chicks and 17 mg/kg body weight for 16-day-old nestlings. Growth rates were significantly reduced at 13 and 17 mg fluoride/kg body weight (the highest doses at which growth was monitored). Most of the early work on mammals was carried out on domesticated ungulates. Fluorosis has been observed in cattle and sheep. The lowest dietary level observed to cause an effect on wild ungulates was in a controlled captive study with white-tailed deer (Odocoileus virginianus) in which a general mottling of the incisors characteristic of dental fluorosis was noted in the animals at the 35 mg/kg diet dose.

Aluminium smelters, brickworks, phosphorus plants and fertilizer and fibreglass plants have all been shown to be sources of fluoride that are correlated with damage to local plant communities. Vegetation in the vicinity of a phosphorus plant revealed that the degree of damage and fluoride levels in soil humus were inversely related to the distance from the plant. Average levels of fluoride in vegetation ranged from 281 mg/kg in severely damaged areas to 44 mg/kg in lightly damaged areas; at a control site, the fluoride concentration was 7 mg/kg. Plant communities near an aluminium smelter showed differences in community composition and structure due partly to variations in fluoride tolerance. However, it must be noted that, in the field, one of the main problems with the identification of fluoride effects is the presence of confounding variables such as other atmospheric pollutants. Therefore, care must be taken when interpreting the many field studies on fluoride pollution.

The original findings of fluoride effects on mammals were from studies in the field on domestic animals such as sheep and cattle. Fluoride can be taken up from vegetation, soil and drinking-water. Tolerance levels have been identified for domesticated animals, with the lowest values for dairy cattle at 30 mg/kg feed or 2.5 mg/litre drinking-water. Incidents involving domesticated animals have originated both from natural fluoride sources, such as volcanic eruptions and the underlying geology, and from anthropogenic sources, such as mineral supplements, fluoride-emitting industries and power stations. Symptoms of fluoride toxicity include emaciation, stiffness of joints and abnormal teeth and bones. Other effects include lowered milk production and detrimental effects on the reproductive capacity of animals. The lowest dietary concentration of fluoride to cause fluorosis in wild deer was 35 mg/kg. Investigations of the effects of fluoride on wildlife have focused on impacts on the structural integrity of teeth and bone. In the vicinity of smelters, fluoride-induced effects, such as lameness, dental disfigurement and tooth damage, have been found.