A comparative analysis of water quality guidelines for fluoride in Canada and Spain

Although anthropogenic fluoride (F−) pollution is a serious worldwide environmental problem, only a few countries have currently established national water quality criteria for the protection of freshwater biota. Since Canada is a global leader in biodiversity conservation that exhibits restrictive water quality benchmarks, I carry out a comparative analysis of water quality guidelines for fluoride in Canada and Spain. The Canadian water quality benchmark of 0.12 mg F−/l (maximum allowable concentration) prevents Canada’s fresh waters from significant adverse events of fluoride pollution, thereby protecting sensitive native aquatic invertebrates and adult-migrating Pacific salmon. By contrast, the Spanish water quality benchmark of 1.7 mg F−/l (annual mean concentration) allows not only continuous levels of fluoride pollution more than six times higher than natural fluoride concentrations in the fresh waters of mainland Spain, but also much higher discontinuous levels of fluoride pollution (> 15 mg F−/l). This unacceptable scenario is contrary to the current environmental goal of “zero pollution” in the European Union. In view of the existing toxicological data, a Spanish water quality guideline of 0.15−0.3 mg F−/l (maximum allowable concentration) seems much more reasonable. The recommended water quality guideline for fluoride would much better protect sensitive native fish and invertebrate species, and prevent significant bioaccumulation of fluoride in tolerant freshwater organisms.