mental factors, such as poor nutrition and health status, patients may suffer
severe skeletal dysfunction. Vomiting and neurological complaints have also
been observed in some patients. Increased levels of F in serum and urine
usually occur. Fluoride exposure leads to cell damage and induces necrosis.
Eventually, F produces massive impairment in the functions of vital organs,
particularly when given orally.
In some parts of the world, such as India, Mexico, and China, the water
supplies in many villages (usually from wells) contain high levels of F, in some
cases higher than 20 ppm. As a result, osteofluorosis is common. Published
reports indicate that in China approximately 20 million people may be afflicted
by chronic F poisoning.
25 As mentioned previously, the dramatic increase in
the use of coal as an energy source has resulted in many parts of China
suffering from rising emissions of F into the environment. Research conducted
by Ando et al.
6 showed high incidences of dental and skeletal fluorosis in some
rural areas in China.
Dental fluorosis is the first sign of chronic F toxicity. It is manifested by
white, yellow, brown, and black discoloration of tooth enamel, either in spots
or in horizontal streaks. One of the earliest symptoms of dental fluorosis is
mottled enamel.
Skeletal fluorosis refers to accumulation of F in skeletal tissues and is
associated with pathological bone formation. It is one of the most severe effects
of F on humans, and is caused by intake of elevated levels of F over a long
period. In the F-afflicted areas studied by Ando et al.,
6 combustion of coal and
coal bricks was found to be the primary source of gaseous and aerosol F in the
human environment. Airborne F from the combustion of coal was found to
pollute extensively both the living environment and the food, such as corn,
chilies, and potatoes, that the residents consume.
Several groups of researchers have reported reproductive effects of F in
humans.
26,27 Ortiz-Perez et al.
28 recently studied the reproductive parameters
in Mexican residents. Two groups of male residents were identified: the highfluoride-exposed group (HFEG), those exposed to F at 3 to 27 mg/day, and the
low-fluoride-exposed group (LFEG), exposed to 2 to 13 mg/day. Increased
urinary F levels (3.2 mg/g creatinine vs. 1.6 mg/g creatinine) were found in the
HFEG, compared with the LFEG. Levels of reproductive hormones were also
measured; the HFEG showed higher follicle stimulating hormone but lower
inhibibin-B, prolactin, and free testosterone serum concentrations than the
LFEG, while no differences were found for total testosterone, estradiol, or
lutenizing hormone between the two groups.
28
10.7 BIOCHEMICAL EFFECT
10.7.1 IN PLANTS
Fluoride is widely known to be a metabolic inhibitor. In plants, F affects many
biological processes, including glycolysis, Krebs-cycle reactions, photosynthEnvironmental Fluoride
163
[16:52 26/8/04 P:/CRC PRESS/4365 MING-HO.751 (1670)/4365-010.3d]
Ref: 4365 MING-HO YU Chap-010 Page: 163 149-170
severe skeletal dysfunction. Vomiting and neurological complaints have also
been observed in some patients. Increased levels of F in serum and urine
usually occur. Fluoride exposure leads to cell damage and induces necrosis.
Eventually, F produces massive impairment in the functions of vital organs,
particularly when given orally.
In some parts of the world, such as India, Mexico, and China, the water
supplies in many villages (usually from wells) contain high levels of F, in some
cases higher than 20 ppm. As a result, osteofluorosis is common. Published
reports indicate that in China approximately 20 million people may be afflicted
by chronic F poisoning.
25 As mentioned previously, the dramatic increase in
the use of coal as an energy source has resulted in many parts of China
suffering from rising emissions of F into the environment. Research conducted
by Ando et al.
6 showed high incidences of dental and skeletal fluorosis in some
rural areas in China.
Dental fluorosis is the first sign of chronic F toxicity. It is manifested by
white, yellow, brown, and black discoloration of tooth enamel, either in spots
or in horizontal streaks. One of the earliest symptoms of dental fluorosis is
mottled enamel.
Skeletal fluorosis refers to accumulation of F in skeletal tissues and is
associated with pathological bone formation. It is one of the most severe effects
of F on humans, and is caused by intake of elevated levels of F over a long
period. In the F-afflicted areas studied by Ando et al.,
6 combustion of coal and
coal bricks was found to be the primary source of gaseous and aerosol F in the
human environment. Airborne F from the combustion of coal was found to
pollute extensively both the living environment and the food, such as corn,
chilies, and potatoes, that the residents consume.
Several groups of researchers have reported reproductive effects of F in
humans.
26,27 Ortiz-Perez et al.
28 recently studied the reproductive parameters
in Mexican residents. Two groups of male residents were identified: the highfluoride-exposed group (HFEG), those exposed to F at 3 to 27 mg/day, and the
low-fluoride-exposed group (LFEG), exposed to 2 to 13 mg/day. Increased
urinary F levels (3.2 mg/g creatinine vs. 1.6 mg/g creatinine) were found in the
HFEG, compared with the LFEG. Levels of reproductive hormones were also
measured; the HFEG showed higher follicle stimulating hormone but lower
inhibibin-B, prolactin, and free testosterone serum concentrations than the
LFEG, while no differences were found for total testosterone, estradiol, or
lutenizing hormone between the two groups.
28
10.7 BIOCHEMICAL EFFECT
10.7.1 IN PLANTS
Fluoride is widely known to be a metabolic inhibitor. In plants, F affects many
biological processes, including glycolysis, Krebs-cycle reactions, photosynthEnvironmental Fluoride
163
[16:52 26/8/04 P:/CRC PRESS/4365 MING-HO.751 (1670)/4365-010.3d]
Ref: 4365 MING-HO YU Chap-010 Page: 163 149-170