Fluoride levels in water and sewerage

The following excerpts may be useful in the present discussion of fluoride in sewage. Both are taken from articles written by me or with Anne Anderson that have been published in Fluoride and are available on Elke's website www.cadvision.com.

1.Foulkes, R.G., Anderson, A., Impact of Artificial Fluoridation on Salmon Species in the Northwest USA and British Columbia, Canada. Fluoride 27 (4) 220-226, 1994.

"In fluoridated areas, drinking water, obtained from surface water with an average fluoride concentration of 0.1-0.2 mg/L (16), is raised to the "optimal" level of 0.7-1.2 mgF/L by the addition of sodium fluoride, hydrofluosilicic acid, or sodium silicofluoride. Fluoride, in community drinking water, enters the fresh water ecosystem in various ways. Surface run-off from fire-fighting, washing cars, and watering gardens may enter streams directly or through storm sewers at optimal concentration, 0.7-1.2 mgF/L. Most enters during waste water treatment.

Masuda (17) studied a large number of cities and calculated the concentrations in waste water that were in excess of the concentration present in the cities' water supplies. In raw sewage, this was 1.30 mgF/L; primary treatment reduced this slightly to 1.28 mgF/L; secondary treatment to 0.39 mgF/L. Singer and Armstrong (18) found 0.38 mgF/L in unfluoridated sewage and 1.16-1.25 mgF/L fluoridated sewage.

It is clear that, in the case of artificially fluoridated communities the concentration of fluoride in both surface run-off and sewer effluent exceeds 0.2 mgF/L. The concentration of fluoride in receiving waters depends on a number of factors: background level (i.e., concentration above effluent outlet); concentration of community water before fluoridation: amount of fluoride added; and. the rates of flow of production, discharge, and receiving water.

Studies show that elevated concentrations in fresh water receiving fluoridated effluent may persist for some distance. Bahls (19) showed that the effluent from Bozeman Montana of 0.6-2.0 mgF/L, discharged into the East Galletin River did not return to the background level of 0.33 mgF/L for 5.3 km. Singer and Armstrong (18) reported that a distance of 16 km was required to return the Mississippi River to its background level of 0.2 mg/FL after receiving the effluent of 1.21 mgF/L from Minneapolis-St Paul.

Although dilution reduces concentration over distance, the amount of fluoride in effluent is either deposited in sediment locally or is carried to the estuary where it may persist for 1-2 million years (16) or may re-contaminate if dredging were to take place. Sewage sludge, a product of secondary treatment systems must contain high concentrations of fluoride. However, this is not measured, routinely, in the jurisdictions that were contacted for this study. This also, when spread on agricultural land, including forests, is a hazard in the "critical habitat" of salmon species. During application, aerosols are created that may be ingested by animals or contaminate surface water. The sludge adds toxic substances to the soil. Fluoride can move into ground water and the run-off of soil particulates may enter streams that play a role in the life cycle of salmon. Effluent from fluoridated cities is also discharged into tidal waters. Sea water has been shown to have a higher concentration of fluoride than unpolluted surface water (16). This concentration of 1.35-1.4 mgF/L is total fluoride. Ionic fluoride is 0.4-0.7-mgF/L and a similar amount is bound in ionic form to magnesium (20)".

2. Foulkes RG, Inorganic Fluorides, Canadian Environmental Protection Act (Priority Substances List Assessment Report, Government of Canada 1993, Fluoride, 1995 Feb, 28:1 29-3295, Review.

"Discussion The strong suit in this study is the concise review of the properties, production and uses of inorganic fluorides, and uses of inorganic fluorides, and the known effects of anthropogenic sources of fluoride on plants and other biota such as ungulates and aquatic species. In a section entitled "Exotoxicity", the Report discusses a number of key studies, selected on the basis of "proper controls, measured toxicant concentrations, acceptable protocols and identification of the most sensitive biota".

From these, those responsible for the study deduced that inorganic fluorides are entering the Canadian environment at concentrations that may cause long-term harmful effects to biota in aquatic and terrestrial ecosystems. For example, with regard to the effects on aquatic organisms, the authors extrapolate laboratory findings to the field, to yield estimated adverse effect thresholds (lethal, growth impairment, and decreased egg production) of 0.28 mg/L fluoride for fresh water species and 0.5 mg/L fluoride for marine species. These are exceeded by many anthropogenic sources. With regard to the adverse effects of inorganic fluoride, especially air emissions, the authors review inorganic fluoride toxicity to plants and animals, especially herbivores. The white-tailed deer consuming contaminated browse, was used as a "model". The authors concluded that inorganic fluorides from anthropogenic sources result in concentrations in some Canadian plants and air that may cause long-term adverse effects to biota in terrestrial ecosystems.

The weakness of this Report that could rob it of total credibility is the obvious protection of the Government-sanctioned process of adding inorganic fluoride to drinking water. In the preceding example of the effects thresholds for aquatic organisms, no mention is made that one of the anthropogenic sources discharging inorganic fluoride into Canadian water that exceed these, is effluent from fluoridated cities that may persist, in fresh water, for some distance.

In fact, the absence of an estimate of inorganic fluoride from this source, in the text and in the accompanying table (Table 1), is conspicuous. Total inorganic fluoride emitted to the environment annually in Canada from anthropogenic sources is estimated to be 23,500 tomes. The amount released to the water is estimated to be 13,500 tonnes, 80% of which is attributed to phosphate fertilizer production (11,000 tonnes). The authors give indirect evidence to enable the reader to calculate that approximately- 10 million people in Canada are "fluoridated" and that the annual release of inorganic fluoride from this source is approximately 2000 tonnes. This puts this source in second place, behind phosphate fertilizer production, but ahead of chemical production (1362 tonnes ), coalfired power (555 tonnes), primary aluminum production (307 tonnes), and others that are identified. In the Recommendations of the Report a request is made for information on the extent of releases from municipal drinking water fluoridation. With the authority of the Government of Canada and two Ministries, it is surprising that this information was not obtained during data collection."

References are on the website: www.cadvision.com

We have not been able to obtain from any jurisdiction an analysis of fluoride in sewage sludge. The authorities inform us that it is not measured.

Richard Foulkes, MD, Andersfoulkes@cs.com