| dc.description.abstract | Excessive ingestion of fluoride can cause dental and skeletal lesions
and in severe circumstances adversely affect health and productivity
performance of domestic animals. The objectives of this study were to
investigate fluoride dietary sources, effects of fluoride on milk production,
excretion of fluoride in cow milk and urine and fluoride toxicity in rats.
Fluoride concentration was determined using fluoride ion specific electrode
and the mean recovery percentages were: 92.4 ± 7.7% (n=114).
One hundred and four samples of feedstuffs and 149 water samples for
dairy cattle were collected from six dairy co-operative societies within
Kiambu and Thika districts of Kenya during the wet and dry seasons of the
yearl994 in a cross-sectional study. The mean fluoride concentration in
feeds from Nderi, Kikuyu, Chania, Limuru, Kiambaa and Lari co-operative
societies were: 19.5 ± 11.3 (n=19) 24.1 ± 28.6 (n=22), 55.2 ± 73.7 (n = 18),
67.6 ± 93.4 (n=15); 9l.9 ± 226.3 (n=24) and 203.4 ± 243.2 (n=6) mgF/kg,
respectively. Individual dairy co-operative society and the type of sample
significantly (p <0.05) influence? fluoride concentration in feedstuffs. The
overall mean fluoride concentration in water was 0.25 ± 0.45 mg/L (n=149).
The fluoride concentration in water during the dry season were significantly
(p< 0.05) different from fluoride concentration during the wet season.
. One hundred and thirty dairy milk and 106 urine samples of dairy cattle
were obtained for fluoride analysis. The mean fluoride level in milk was
0.066 ± 0.14 mg F/kg while mean fluoride concentration in cows' urine was
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l.28 ± l.0 mg F/kg. Seasons, breed of cattle, source of water and dairy cooperative
society did not affect milk and urine fluoride concentration
significantly (p> 0.05).
Two hundred and forty SIX dairy cows were assessed for milk
production. The mean milk production was 3.13 ± 2.78 lIcow/day. There
was a significant difference (p< 0.05) in mille production due to season and
dairy co-operative society. Water and feedstuff fluoride concentration did
not significantly influence (p>0.05) milk production.
The toxic effects of fluoride in female wistar rats (n=100) were
investigated within a time-span of 96 to 843 days. Rats were randomly
divided into 10 groups of 10 rats per group namely A, B, C, D, E, F, G, H, I
and 1. Each group was provided with commercial rat feed of known fluoride
content and graded doses of fluoride in de-ionised water. Groups A, B, C,
D, E and F were fed on 1, 5, 10, 30, 60, 80 mg F L-1 equivalent to 0.087,
0.42, 0.823, 2.667, 5.45 and 7.804 mg/kg sodium fluoride in de-ionised
water respectively. Group G, H, I and J were fed on 2 % Magadi salt
solution, de-ionised water (control), 2 % commercial mineral salt solution
and 2 % tea extract respectively. The following variables were monitored
for each group; bodyweight, organ weights, water (fluoride) intake, feed
intake, fluoride concentration in tissues and fluoride concentration in faeces.
Sixty-two rats were sacrificed during the time of the experiment for tissue
fluoride assays while twenty-eight rats were killed for pathology tissue
processing. Ten rats died in the course of the experiment and were dissected
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for fluoride tissue assay and pathology. The dose of fluoride in drinking
water significantly influenced (p<0.05) body weight, tissue fluoride
concentration and organ weight. Rats fed on magadi salts had the lowest
mean weight (186.7 ± 18.8 g) as compared to the control group of rats
which had a mean weight of 280.0 ± 17.1 g whereas group C had the
highest mean weight of343.7 ± 40.7 g.
Histopathological examination on liver, kidney, lungs and the heart
organs of rats from groups A, B, C, H, and J revealed no pathological
changes, however in groups D, E, F, G and I, degenerative changes, hepatic
and myocardial haemorrhages were observed. The pathological changes
became more severe as the concentration of fluoride was increased. Tumour
growths were observed in three rats: uterine adenocarcinomas (group A and
group C) and a fibroma (group J). One control rat from group H had a
pyogranulomatous nodule as well.
Fluoride concentration in the muscle, femur, incisor teeth and lower
jaw were: 19.0 ± 28, 693.9 ± 536.4, 730.5 ± 576.8 and 1063.5 ± 829.6 mg
/kg respectively. Fluoride concentration in lower jaw were significantly
higher (p<0.05) than in muscle tissues. Faecal fluoride excretion was
significantly influenced (p<0.05) by time of fluoride exposure.
Nine food substances (Tilapia, Nile perch, lettuce, spinach, bovine,
cabbage, kales, goat and chicken) were obtained from the local market and
used to prepare fresh soups. Fluoride concentration in ninety fresh soup
samples were investigated upon boiling for two hours. Soup samples were
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drawn from each preparation at intervals of 15 minutes. Tap water was used
as a control. The type of food substance used for soup preparation and
boiling significantly influenced fluoride concentration in the soup. Fluoride
concentration in Tilapia, Nile perch, lettuce, spinach, bovine, cabbage,
kales, goat, and chicken soup were: 5.01 ± l.27, 2.92 ± 0.54, 0.67 ± 0.34,
0.66 ± 0.28, 0.32 ± 0.05, 0.25 ± 0.05, 0.24 ± 0.03, 0.22 ± 0.04 and 0.16 ±
0.04 ppm respectively. Soup prepared from Tilapia fish had significantly
higher, (p < 0.05) fluoride concentration than other meat and vegetable
soups.
This cross -sectional study has shown that dairy cattle from Kiambu and
Thika districts are exposed to high concentration of fluoride especially through
mineral supplements. Consequently, there is need to establish standards for
fluoride in mineral mixes and other animal feeds. In addition this study has
shown that fluoride is essential for normal growth of rats and the optimal
fluoride intake in drinking water is 10 ppm. Further, the analytical method used
in this study was found suitable for determination of fluoride in water, soup, food
substances and animal feeds. ;
Overcooking may increase fluoride concentration In Tilapia soup and
further investigation should be carried out on bioavailability of fluoride from fish
soup. In addition further investigation should be done to establish whether
fluoride is tumorigenic in rats. | en |
