FLUORIDE 30 (1)  1997, p. 85-88	International Society for Fluoride Research	Table of Contents

Fluoride Vol. 30 No. 2 85-88 1997. Research Report

SKELETAL CHANGES WITH TOXICITY
FROM FLUORIDE AND ALUMINUM

X G Chen, S Zhou, J Jiao, Y H Ding and Z Q Zhao
Guiyang, Guizhou, China

SUMMARY: Radiographic examination of 39 patients with toxicity from both fluoride and aluminum showed typical features of metabolic skeletal transformation including osteoporosis in cortical bone and osteosclerosis in cancellous bone. The pro-cortical bones were transformed into soft cortical bones and the pro-cancellous bones were transformed into disordered net-like bones with a large amount of osteoid. These features may be useful in the classification of skeletal fluorosis.

Key words: Aluminum; Fluoride; Radiography; Skeleton; Toxicity.

INTRODUCTION

The radiographic skeletal changes associated with intoxication by both fluoride and aluminum are complicated with features of osteosclerosis, osteomalacia, and osteosclerosis with rickets.^1-3 Wang has described skeletal transformation in metabolic skeletal disease⁴ but this effect has not previously been described in combined intoxication by fluoride and aluminum. These combined effects are reported in the present study.

MATERIALS AND METHODS

Thirty-nine patients, 16 male and 23 female, mean age 12.4 years, were studied from districts of Shui City in Guizhou Province in which chronic fluoride toxicity or fluorosis was endemic. The corn used as the major food source in these areas was commonly contaminated by soil and coal by a method of cooking involving baking with a mixture of mud and coal.⁵ Many of the subjects were symptomatic and had malformations of their limbs and joints.⁵  Serum and urine levels of fluoride, aluminum and calcium were elevated compared to normal controls (Table 1).

TABLE 1. Serum and urine levels of fluoride, aluminum and calcium
	Patients	Normal controls
Serum aluminum	0.36 ± 0.16*	0.25 ± 0.09
Urinary aluminum	0.13 ± 0.07*	0.08 ± 0.05
Urinary fluoride	3.71 ± 1.43*	1.26 ± 0.84
Urinary calcium	28.7 ± 40.8*	9.63 ± 9.16
Values are mean in µg/L ± S.D.   * Compared to normal controls p < 0.5

Histological examination was made of bone obtained by biopsy from two patients. Radiographs were taken on all patients of the pelvis, left arm, legs and any malformations present.

RESULTS

The changes seen at histology involved decreased ossification, a widening of the spaces between the trabeculae, osteoporosis, dilatation of Haversian canals in cortical bone, a rarity of osteoblasts, and increased osteoid. Radiographic features of skeletal transformation were seen in the 39 patients with osteoporosis in cortical bone and osteosclerosis in cancellous bone. The osteoporosis of cortical bone was seen most frequently in curved parts of the tibia and fibula (Table 2, Figures 1 and 2).

TABLE 2. Radiographic features of osteoporosis in cortical bone (n=39)
Radiographic feature	Present (%)
Widening of cortex with decreased density	22 (56%)
Irregular vertical lucent lines	15 (38%)
Localized areas of ground-glass-like low density cortex	10 (26%)
Subperiosteal bone reabsorption	5 (13%)

The osteosclerosis in cancellous bone was seen in the pelvis, distal femur, and the proximal parts of the tibia and fibula (Table 3, Figure 3).

TABLE 3. Radiographic features of osteosclerosis in cancellous bone (n=39)
Radiographic feature	Present (%)
Coarse and sparse haziness of trabeculae	12 (31%)
Patchy dense pieces of boneless structure	11 (28%)
Disordered gross range of trabeculae*	8 (21%)
Fusion of thin and thick trabeculae	7 (18%)
Coarse and net-like haziness of trabeculae	6 (15%)
* 3-4 times greater diameter, than normal trabeculae

DISCUSSION

The 39 patients who had toxicity from both fluoride and aluminum, as a result of eating corn contaminated with mud and coal, showed radiographic features of skeletal metabolic disease.⁵  Dai has shown in animal studies that fluoride and aluminum can produce both independent and interactive effects on bone.⁶  Fluoride affected the synthesis of osteo-cytoplasm and resulted in production of increased osteoid. Aluminum affected the mineralization of osteo-cytoplasm and inhibited the calcification of osteoid. Together fluoride and aluminum stimulated osteoclastic activity and the parathyroids resulting in bone reabsorption and skeletal transformation.

Wang described the concept of skeletal transformation in skeletal metabolic disease: bone reabsorption in trabeculae and cortex by osteoclasts is accompanied by ossification by osteoblasts.⁴ The result is the transformation of the pro-compact cortex into soft cortical bone with the production of osteoporosis of cortical bone. Similarly, the pro-cancellous bone is changed into a disordered net-like bone with a large amount of osteoid present forming osteosclerosis of cancellous bone.

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The radiographic features of the skeletal transformation in toxicity from both fluoride and aluminum have not been described previously. Two features occur. The first involves osteoporosis of cortical bone, and comprises: a) osteoporosis and laminated changes in the cortex, dilatation of Haversian canals; b) decreased density and a ground-glass-like cortex; and loss of the border between the cortex and the medullary space; a bone density similar to that of soft tissue; c) a widening of the cortex caused by the accumulation of a large amount of osteoid; d) haziness of the margin of the cortex resulting from some subperiosteal bone reabsorption. Secondly, osteosclerosis of cancellous bone occurs with: a) coarse and net-like haziness of trabeculae resulting from the accumulation of osteoid on the surface of the trabeculae; b) thin and thick fusion of trabeculae; increased bone density resulting from the occurrence of increased amounts of bone and osteoid; c) localized coarse compact bone resulting from disordered ossification; d) patchy dense areas resulting from accumulations in the medullary space, trabeculae and metaphyses.

Osteoporosis, osteomalacia, osteosclerosis and skeletal transformation may exist together and may not be easily differentiated. For example, in the radiographs of the pelvis of patients with toxicity from fluoride and aluminum, bone density was increased, trabeculae showed gross haziness, and the malformation of osteomalacia was also present. In the diaphysis of the long bones the radiographs showed a curving malformation and a ground-glass-like laminated cortex with decreased density and increased thickness. In the metaphysis the trabeculae of the cancellous bone showed osteoporosis and coarseness together with disordered and compact ossification.

Study of the radiographic features of skeletal transformation in toxicity from fluoride and aluminum may be helpful in interpreting radiographs showing the increased density of osteosclerosis, varieties of osteomalacia, and osteosclerotic osteomalacia.⁷  Because the appearances of skeletal transformation include osteoporosis of cortical bone, osteosclerosis of cancellous bone, and osteomalacic malformation, they could be regarded as being a "mixture type" of chronic fluoride toxicity or fluorosis. They may contribute to establishing a new classification of endemic chronic fluoride toxicity.

REFERENCES

1. Chen XG, Jiao J, Zhou S et al. Skeletal radiographic diagnosis of F-Al combined intoxication in Shui City in Guizhou Province. Journal of Guiyang Medical College 10 201-203 1991 (in Chinese).
2. Andreoli SP, Smith JA, Bergstein JM. Aluminium bone disease in children: radiographic features from diagnosis to resolution. Radiology 156 663-667 1985.
3. Teotia SPS, Teotia M, Singh DP et al. Environmental fluoride and metabolic bone disease II: an epidemiological study. Fluoride 17 14-22 1984.
4. Wang YZ. Metabolic skeletal disease I: osteomalacia, osteosclerosis, and skeletal transformation. Chinese Journal of Radiology 25 305-307 1991 (in Chinese).
5. Li FC. Case report: disease caused by cooking corn with a mixture of mud and coal. Chinese Journal of Preventive Medicine 22 225-229 1988 (in Chinese).
6. Dai GY, Wei ZD, Zhou LY. Experimental research on the combined influence of F-Al. Journal of Guiyang Medical College 15 81-85 1990 (in Chinese).
7. Li JX, Chuei YZ, Zou MC et al. Osteosclerosis or osteomalacia? Chinese Journal of Radiology 21 65-68 1987 (in Chinese).

AUTHORS: Department of Radiology, Affiliated Hospital of Guiyang Medical College, Guizhou, 550001, People's Republic of China.
Presented at the XXth Conference of the International Society for Fluoride Research, Beijing, People's Republic of China, September 5-9, 1994.

FLUORIDE 30 (2)  1997, p. 85-88	International Society for Fluoride Research
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