Introduction
Examples of the environmental effects of fluoride emissions can be found in most countries, but some of the more high-profile cases are worth considering in detail because they demonstrate the magnitude of potential effects and the improvements in investigative techniques that have taken place in the last 50 years. Some have played a vital part in changing public and political attitudes and some have led to better envi- ronmental protection. Others have raised interesting scientific questions. Selecting case histories that demonstrate the diversity of problems encountered in the field, scien- tifically, forensically and even politically, was difficult, not because there was a short- age of possibilities, but mostly because it was difficult to acquire sufficiently detailed information to weave a comprehensive story. In some cases, one or more key elements were inaccessible. There were a number of excellent prospects, including:
aluminium smelting in the Rhône Valley of Switzerland and injury to apricots, grapes, other fruits and forests over many years; the massive HF release from a petroleum refin- ery in Texas in 1987; cherry and apricot damage in The Dalles, Oregon, decided (in part) by a federally appointed scientific arbitration panel; the widespread fluorosis of livestock in the Bedfordshire, Yorkshire
and Staffordshire areas of England; injury to citrus from phosphate-fertilizer industry emissions in Florida during the 1950–1970 period; steel smelting and plant and animal damage in Utah; aluminium smelting and allegations of damage within Glacier National Park; and several others. The five cases we have chosen represent fluoride problems in all their ‘glory’ – damage to farmlands, fruits, forests and indigenous plant life, and to farm animals and humans.
Some cases were clear-cut, some equivocal and some unproved. The problems were resolved by lawsuit, public outcry, inter- national cooperation, a Queen’s Inquiry and time.
Aluminium Smelting at Fort William and Kinlochleven, Scotland
Background
This case occurred in the 1940s, after the publication of Roholm’s (1937) seminal work, and therefore at a time when knowl- edge of fluoride effects on humans and livestock was just developing. Industrial workers in the aluminium smelters at Fort William and Kinlochleven were exposed to high concentrations of several pollutants and concern grew about their health and the
©L.H. Weinstein and A. Davison 2004.Fluorides in the Environment
(L.H. Weinstein and A. Davison) 119
potential effects of emissions on the local area. The inquiry was one of the most comprehensive of its time, but, reading the report of the case now (Agateet al., 1949), the investigative techniques seem haphaz- ard at times, probably because the scientists were finding their way in uncharted terri- tory, and the report itself falls far short of current standards in that there is missing detail about some of the procedures. At the time, analytical techniques for fluoride determination were subject to significant errors, so great care has to be taken in inter- preting some of the data. Nevertheless, it was an important study that brought fluoride to the attention of British scientists and the public. It also had an influence on the second case history in the USA.
The environmental concerns about the aluminium smelters near Fort William and Kinlochleven, operated by the British Aluminium Company, were principally related to fluoride toxicity to humans and other animals. Effects on plants appear to have been considered as a peripheral problem. In 1945, the Department of Health for Scotland selected a group of scientists to investigate concerns and to report to the Fluorosis Committee. The purpose was to examine the complaints from areas near the factories and ‘to determine effects of exposure of fluorine compounds on workers employed in factories manufacturing alu- minium in Inverness-shire by an electrolytic process, and also to determine any similar effects on those living in the neighbourhood of such factories’ (Agateet al., 1949). Mem- bers or designees of the Fluorosis Committee visited the sites of the smelters twice in 1945 and once in 1946, conducting medical examinations and collecting blood, urine, atmospheric, grass and soil samples for fluoride analyses. The main clinical and environmental aspects of the study were carried out by the staff of the Medical Research Council’s Department for Research in Industrial Medicine at the London Hospital, the Chief Dental Officer of the Department of Health and Professor G.F.
Boddie of the Royal Veterinary College, who studied the effect of fluorine-containing compounds on livestock in the area.
Location of the smelters and the aluminium reduction processes
The smelters were located in the Western Highlands of Scotland, the Kinlochleven smelter being about 15 km south-south-east of Fort William. Both smelters were situ- ated in valley systems, with lochs to the west of both Fort William and Kinlochleven (Fig. 5.1). The Fort William smelter utilized both prebake and Söderberg ‘green paste’
anodes. The oldest pot room, referred to as ‘Furnace room A’ and dating from 1929, used prebake anodes but had no mechanical ventilation, depending on natural draughts to carry the fumes out through the side and roof vents.
Radiant heat from the furnaces makes it very hot in this furnace room and the air is heavily charged with fine dust which settles everywhere as a white deposit;
gases produced by the furnaces are also discharged directly into the air of the room.
(Agateet al., 1949) Furnace room B dated from 1938 and the furnaces (or pots) were referred to as old- type Söderberg units, a technology which was notoriously dirty, although there was a ventilation unit that carried air at 855,000–
956,000 ft3/min (24,000–27,000 m3/min), resulting in an air exchange time of 3.5–4 min. This resulted in a lower concen- tration of dust and fumes but ‘a consider- able fog of pitch fumes from the Söderberg electrodes is usually present’. Furnace room C was the most modern, dating from 1942 and fitted with the latest Söderberg technology. Air was withdrawn from each pair of pots at the rate of 7500–9000 ft3/min (212–255 m3/ min), theoretically resulting in a complete exchange of air in the pot room once every 2.2–2.6 min. In relation to the external environment, the important fact is that the fumes extracted from all three pot rooms escaped to the outside atmosphere unscrubbed.
The smelter at Kinlochleven was older than the one near Fort William, and the two furnace rooms were similar to Furnace room A and Furnace room C at Fort William.
Unfortunately, the situation at Kinlochleven
was not documented in detail by the Medical Research Council Inquiry (Agate et al., 1949), so the subsequent discussion will refer primarily to Fort William.
Meteorology and the fume path The average wind speed during the period from 1932 to 1944 was from about 0.4–5.4 m/s about 90% of the time, and there was little difference between months of the year. Monthly ambient temperatures never exceeded 60°F (15.6°C), even in June, July and August, and averaged 47.7°F (8.7°C). During this period, rainfall aver- aged about 77 inches (nearly 200 cm) per year, making it one of the wetter districts in
the British Isles. The relative humidity was fairly constant throughout the year, with a mean value for the period of 80.8%.
An obvious plume of dense white smoke drifted from the pot rooms at Fort William and was carried in a north-north-easterly direction, with secondary flow to the south- south-west. Flow in other directions was minor (Fig. 5.1).
Pot-room atmospheres
Workers in Furnace room A, which was the worst of the furnace rooms, with no forced ventilation, complained that, after a period in this room, their eyes and skin became inflamed. The atmosphere in Furnace room Fig. 5.1. Map of the Fort William area in 1949 showing the location of the aluminium smelter, three farms (Nevis Bridge Croft, Claggan and Torlundy) and grass fluoride concentrations (mg F/kg dry wt). (Redrawn from Agateet al. (1949) Agate, J.M., Bell, G.H., Boddie, G.F., Bowler, R.G., Buckele, M., Cheeseman, E.A., Douglas, T.H.J., Druett, H.A., Garrad, J., Hunter, D., Perry, K.M.A., Richardson, J.D. and Weir, J.B. de V.
(1949)Industrial Fluorosis: a Study of the Hazard to Man and Animals near Fort William, Scotland. Medical Research Council Memorandum No. 22, H.M. Stationery Office, London, according to licence number C02W0002815.)
B, although fitted with an exhaust system, was not as clear as in Furnace room A,
‘because there is a considerable fog of pitch fumes produced by the baking of the “green paste” in the Söderberg electrodes’. Furnace room C was described as clean, relatively cool and free of fumes. The fluoride content of the furnace-room atmospheres is shown in Table 5.1. Although the concentrations are probably of the right order of magni- tude, some of the authors’ comments about the technique indicate that they were not very accurate. They had difficulty measur- ing the volume of air, and the use of a single absorbent bubbler led to loss of some of the fluoride. Furthermore, the proportions of gaseous to particulate fluorides should be interpreted with caution because the tech- nique used to separate the two fractions (an untreated filter-paper) would have overestimated the particulate and under- estimated the gaseous components. When the sampling began, the Second World War blackout restrictions were in effect, so both
forced and natural ventilation were reduced, resulting in very high fluoride concentra- tions. By the time the second set of air samples was collected, the war was over, blackout devices had been removed, venti- lation was much improved and the fluoride concentrations were reduced several-fold in most cases. In general, the data showed that Furnace room A was somewhat worse than B, and C was the cleanest of the three. The atmosphere in pot rooms at Kinlochleven was about on a par with that of Furnace room B at Fort William. Unfortunately, each air sample was taken at a different location in the pot rooms, resulting in wide variations from sample to sample.
The ambient atmosphere
Immediately outside the Fort William pot rooms, the total fluoride in the ambient atmosphere was reported as being from
Date Pot room Total F Gaseous F Particulate F
21–5–45 28–5–45 28–5–45 17–5–45 29–5–45 18–5–45
A A A B B C
3.43 2.15 2.12 2.72 1.49 –
2.54 1.05 1.04 1.77 0.80 (Lost)
0.89 1.10 1.08 0.95 0.69 1.50 Postblackout
22–7–46 23–7–46 23–7–46 25–7–46 22–7–46 22–7–46 23–7–46 25–7–46 23–7–46 23–7–46 23–7–46 25–7–46
A A A (night shift)
A B B B (night shift)
B C C C (night shift)
C
1.08 0.77 1.00 0.37 0.64 0.41 0.70 0.44 0.60 0.14 0.34 0.33
0.58 0.39 0.44 0.18 0.32 0.19 0.27 0.25 0.36 0.04 0.21 0.05
0.50 0.38 0.56 0.19 0.32 0.22 0.43 0.19 0.24 0.10 0.13 0.28 Table 5.1. Concentration of fluoride (mg/m3) in the pot-room atmospheres at Fort William. Each sam- ple was collected at a different location in the pot rooms. (From Agate, J.M., Bell, G.H., Boddie, G.F., Bowler, R.G., Buckele, M., Cheeseman, E.A., Douglas, T.H.J., Druett, H.A., Garrad, J., Hunter, D., Perry, K.M.A., Richardson, J.D. and Weir, J.B. de V. (1949)Industrial Fluorosis: a Study of the Hazard to Man and Animals near Fort William, Scotland. Medical Research Council Memorandum No. 22, Her Majesty's Stationery Office, London, according to licence number C02W0002815.)
16.4mg/m3100 m east-north-east to 164mg/
m3 200 m south-west of the smelter.
Concentrations fell with distance from the works but, even in the centre of Fort William, the air was reported as containing 39.4mg total fluoride/m3. It was assumed that the average person in the town was exposed to 7.2mg/m3 and in nearby Inverlochy to 25.2mg/m3. In environmental terms, these are extremely high concentra- tions and, if they were anywhere near accu- rate, there would have been severe damage to vegetation, which should have been obvi- ous even to lay people. There would have been very few plants left unmarked. The authors’ experience suggests that con- centrations were probably lower, not least because of scrubbing by the heavy rain- fall. In addition, there was a discrepancy between the atmospheric and grass con- centrations (see below), so it is difficult to avoid the conclusion that the analyses overestimated the atmospheric concen- trations outside the factory. This is under- standable because quite low volumes of air were sampled and the analytical tech- niques that were available were prone to interference.
Soil contamination
The soils consisted mainly of deep, acid peat overlying a rock base. About 40 samples were collected at distances up to about 10 km from the smelter. They were collected by cutting plugs of turf and discarding the top inch (2.5 cm), and about six subsamples were combined from an area of about 10 m2. The analytical techniques were not described, so it is not known if the soils were subjected to alkali fusion to ensure release of all of the fluoride. However, the data do show evidence of considerable surface con- tamination (Table 5.2), which extended for as far as about 10 km from the smelter.
The contamination at such distances was probably detectable because of the low background concentration in the peat (see Chapter 2).
Fluoride in forage
The fluoride content of forage is the key to determining the risk of fluorosis in live- stock and other herbivorous animals. Grass sampling was not described except to state that ‘Handfuls of grass were taken.’ How- ever, the individuals who processed the samples were aware that much of the fluoride found in grass samples could be deposited on the leaf surfaces and they were interested in determining if particu- late fluorides were taken into the plant cells. Therefore they attempted to wash the grass but abandoned it because of unidenti- fied ‘practical difficulties’. Although in the original plan the fluoride contents of samples of fruits and vegetables were also to be determined, only a few were found and this phase was abandoned.
Regarding the composition of the indig- enous vegetation, the report states:
Coarse grasses, sphagnum moss, heather and bracken, and clumps of spruce, fir and pine trees are to be seen on the low ground about a mile north-east of the factory. The streams are lined mainly with common alder and dwarf birch. The hillsides are bare of trees except for the western side of Glen Nevis, where the Forestry Commission has planted large numbers of fir trees.
Depth of soil sample (cm) Fluoride content .50–2.5
2.5–7.6 7.6–17.8 17.8–27.9 27.9–38.1
1010 372 400 268 161 Table 5.2. Concentration of fluoride in soil samples (mg/kg, dry wt) at various depths in the north-west corner of the Fort William smelter property. (From Agate, J.M., Bell, G.H., Boddie, G.F., Bowler, R.G., Buckele, M., Cheeseman, E.A., Douglas, T.H.J., Druett, H.A,, Garrad, J., Hunter, D., Perry, K.M.A., Richardson, J.D. and Weir, J.B. de V. (1949)Industrial Fluorosis: a Study of the Hazard to Man and Animals near Fort William, Scotland. Medical Research Council Memorandum No. 22, Her Majesty’s Stationery Office, London, according to licence number C02W0002815.)
Apparently none of this vegetation was sampled or analysed, nor were there any descriptions of foliar symptoms or of plant mortality.
Figure 5.1 shows the fluoride concen- trations in grass. As mentioned earlier, although they are high, they do not appear to be in accordance with the reported atmo- spheric concentrations. They were much lower than would be expected if the atmo- spheric concentrations were correct. The discrepancy might have been due to analytical errors or to the fact that the grass was collected on only one occasion, possibly at a time just after heavy rain. Nevertheless, the values are high enough to indicate that there would have been problems with fluorosis over a considerable area, probably up to distances of 4–5 km in the downwind direction.
Effects on livestock
In 1943, a farmer at Nevis Bridge Croft (south-west of the smelter) complained that his cattle and sheep were suffering from an affliction that he had never previously observed. His animals had been grazing in an enclosed pasture immediately behind the town of Fort William and less than 1 km south of the smelter. Clinical evaluation revealed that tooth formation was abnor- mal: the enamel of incisors was mottled and the teeth were malformed. This condition was found in all adult sheep but not in any of the 6-month-old lambs. The two cows present had mottled incisors that were worn to stubs at the gums. Cheek teeth were badly worn and abnormal in form. By the spring of 1944, there were complaints from other farmers for damage to sheep at the Achentee Farm, a large holding. In a group of 116 sheep grazing about 1.2 km from the smelter, abnormal teeth were found in 72 animals; in another group of 85, 39 were found to be abnormal. The incisor teeth were not only mottled but also brittle, and many of them had broken. In other animals the abrasive resistance of teeth was so low that many had been worn to the gums.
Cheek teeth were often so abnormal in form that the animal could not close its mouth completely. The worn teeth became a pathway for infection, resulting in purulent inflammation of gums and sinuses. In addition to the drastic effects on teeth, an unusual number of animals had rib, pelvis and mandible fractures. Because milk production was also reduced, there was a secondary effect on the normal develop- ment of lambs. Forage contained 44 mg/kg fluoride (on a dry-weight basis). (This is an unusually low value considering the extreme effects on sheep, so it should not be considered as reliable.) No clinical fluorosis was found in cattle at Achentee, probably due to the farmer’s practice of purchasing pregnant cows that were not kept on the pastures for more than 1 or 2 years.
In 1946, the herd of 45 cattle at Torlundy Farm, about 2.8 km north of the smelter, was examined. Most of the dairy cows:
were not in the bodily condition that might be expected at a time of the year when grazing was good . . . the coats of the cows were lacking in lustre and their skins were hard. In contrast to the cows, the young stock were in reasonably good condition.
Incisor teeth in adult animals were mottled, deformed and badly worn. The cheek teeth were affected, as described earlier. In adult animals there was also a relationship between the age of the animal and the degree of dental lesions, with the oldest animals being the least affected. This was due in part to the increase in exposure to fluoride after the smelter began operations.
Peak production and fluoride emissions occurred in 1942. Thus, the older animals had been exposed to lower amounts of fluo- ride during their most vulnerable periods.
In 1945, several cows and sheep were purchased for autopsy. Teeth were in poor condition, as described earlier, and rib bones were often fractured or weak, but other bone deformities were not evident. In both sheep and cattle, there were massive increases in bone fluoride compared with controls (Table 5.3). There was evidence of elevated fluoride in milk of cows and sheep
(average of 0.44 mg/l in cow’s and 0.62 mg/l in ewe’s milk), but these values were not considered to be a public health hazard.
The inquiry concluded that normal dairy farming and successful sheep farming would not be possible near Fort William.
Effects on humans
For this study, employees at Fort William (and a few from Kinlochleven) were sepa- rated into two groups, based upon their degree of fluoride exposure. Group I, the most exposed group, contained 220 men and 22 women. Group II was less exposed;
there were 44 men and 25 women in the group. In the residential areas near the smelter, two additional groups were formed – Group III had 27 men and 52 women and Group IV consisted of schoolchildren from the Inverlochy and Fort William secondary schools. Each person received a complete
physical examination, with particular emphasis on movements of the thoracic cage, vertebral column and joints. Each child was given a complete dental examina- tion. All participants received a detailed radiographic examination (with some defaulters for various reasons). Blood samples for fluoride analysis and cell counts and 24 h urine samples were taken from a smaller number of people. The work- ers in Group I were further subdivided into groups based upon the degree of exposure, with furnace men, stub squad and tappers being in the most exposed group. When questioned about the incidence of back pain, digestive disturbances or dyspnoea (laboured breathing), there did not appear to be an excess incidence of back pain, but there was evidence of more complaints of digestive disorders and coughs. There was also no evidence of an increased incidence of bone fractures among the most exposed group.
Fluoride in urine was highest in the most exposed workers, commensurate with their degree of exposure. Older workers exposed for a number of years exhibited bone abnor- malities typical of workers elsewhere who had been exposed to fluoride. These radio- graphic abnormalities were mainly seen as increased bone density, but none of the workers was found to suffer clinical disability. However, the panel stated:
It does not follow that the risk to health of workers in the older type of furnace room is negligible, for it is well known that the progressive course of fluorosis is slow;
rather are the changes to be regarded as a warning that the conditions under which these men work are such as to call for constant vigilance and for determined efforts to reduce the amount of fluorine to which they are exposed.
It is worth noting that the study of teeth suggested that the local children were less prone to caries than children from other areas.
Regarding effects on human health in areas outside the smelter, the total fluoride intake of the population was not recorded, apart from an abandoned attempt to deter- mine the fluoride content of vegetables.
However, the report stated that although a Rib Mandible
Radius and Ulna Achintree, 1945
Black-face ewe Cheviot wether
2 years Black-face gimmer Cheviot gimmer
12,000 10,400 7,000 10,660
14,100 17,200 9,420 2,140
10,300 8,980 8,170 1,010 Control, Ettrick
Valley, 1945 Black-face ewe Black-face ewe Black-face ewe Grey-face ewe
10,478 17,083 10,382 10,343
10,415 10,111 10,238 10,269
10,279 17,099 10,222 10,211 Table 5.3. Fluoride content (mg/kg) of sheep tissues collected near the Fort William smelter.
(From Agate, J.M., Bell, G.H., Boddie, G.F., Bowler, R.G., Buckele, M., Cheeseman, E.A., Douglas, T.H.J., Druett, H.A., Garrad, J., Hunter, D., Perry, K.M.A., Richardson, J.D. and Weir, J.B.
de V. (1949)Industrial Fluorosis: a Study of the Hazard to Man and Animals near Fort William, Scotland. Medical Research Council Memorandum No. 22, Her Majesty’s Stationery Office, London, according to licence number C02W0002815.)