Ambient Water Quality Criteria for Fluoride

Water Quality

11.0 Research Needs

Fluoride toxicity in aquatic organisms such as Daphnia and rainbow trout is known to be affected by water hardness and water temperature. Other constituents of the water, such as chloride, may also affect fluoride toxicity. A single multifactorial experiment is needed to determine LC₅₀ values for rainbow trout at various combinations of water hardness and temperature. Such experiments would be expected to yield a single equation from which one would be able to derive the LC₅₀ value for fluoride for any combination of water temperature and hardness.

Virtually nothing is known about the fluoride levels, and availability, in forage, crops and agricultural soils throughout British Columbia. A survey of crops, forage and soil fluoride levels should be conducted and the Province's agricultural areas grouped into regions based upon fluoride levels found in forage and crops. This would allow region-specific fluoride levels to be determined for drinking, livestock watering and irrigation waters, which would maintain an acceptable total fluoride dose in the typical diet.

Almost nothing is known about synergistic effects of fluoride with solutes other than copper. There is speculation that the specific cation associated with a fluoride salt may effect fluoride toxicity. Suitable experiments need to be designed and carried out to determine if such effects do occur, and if so, the level at which they occur and the nature of the effect.

Research is needed on the chronic effects of various fluoride levels on salmonid eggs and larvae, and on Daphnia growth and reproduction, especially for soft waters. The effects of low fluoride levels on food organisms must also take into account accumulation in predators as the fluoride moves up the food chain to longer-lived, bony, top predators. Levels not affecting prey may prove unacceptable due to accumulation.


	Water Quality Ambient Water Quality Criteria for Fluoride 11.0 Research Needs Fluoride toxicity in aquatic organisms such as Daphnia and rainbow trout is known to be affected by water hardness and water temperature. Other constituents of the water, such as chloride, may also affect fluoride toxicity. A single multifactorial experiment is needed to determine LC₅₀ values for rainbow trout at various combinations of water hardness and temperature. Such experiments would be expected to yield a single equation from which one would be able to derive the LC₅₀ value for fluoride for any combination of water temperature and hardness. Virtually nothing is known about the fluoride levels, and availability, in forage, crops and agricultural soils throughout British Columbia. A survey of crops, forage and soil fluoride levels should be conducted and the Province's agricultural areas grouped into regions based upon fluoride levels found in forage and crops. This would allow region-specific fluoride levels to be determined for drinking, livestock watering and irrigation waters, which would maintain an acceptable total fluoride dose in the typical diet. Almost nothing is known about synergistic effects of fluoride with solutes other than copper. There is speculation that the specific cation associated with a fluoride salt may effect fluoride toxicity. Suitable experiments need to be designed and carried out to determine if such effects do occur, and if so, the level at which they occur and the nature of the effect. Research is needed on the chronic effects of various fluoride levels on salmonid eggs and larvae, and on Daphnia growth and reproduction, especially for soft waters. The effects of low fluoride levels on food organisms must also take into account accumulation in predators as the fluoride moves up the food chain to longer-lived, bony, top predators. Levels not affecting prey may prove unacceptable due to accumulation.