As shown in Table 5 above, the overall mean Fluoride levels in animals
(mutton and caprine) were
9.58±6.03
and
6.34±2.45
mg/Kg
respectively, while the concentrations for the selected heavy metals ranged
between 0.06±0.02 and 3.66±2.41 mg/Kg. Fluoride levels in plants (leaves, grass and corn maize) ranged
between 4.77±2.52 and 6.27±3.40 mg/Kg while the concentrations for the selected heavy metals ranged
between 0.01±0.01 and 0.48±0.30 mg/Kg. Generally, animal samples had higher concentrations of the
studied elements than plant samples. This is likely because bioaccumulation in
animals is higher than in plants and the ability of animals to move to different
regions while grazing on grass, leaves, and drinking of fluoridated water.
Nguta et al. [25] reported high
levels of fluoride and heavy metals in water and soil around the Kenya fluorspar
factory and therefore, the presence of these elements might have led to the
bioaccumulation in animals and plants. This is
consistent with the report by Baars et al. [9]. These results mean that there
is a potential risk that could be looming on the health of the animals as well
as the human beings who consume meat.
Fluoride and
heavy metals (Fe, Cr, Zn, Cd, and Pb) concentrations
in plants showed that the elemental contents differed among plant samples. This
observation can be attributed to their different capacities for Fluoride and
metal uptake. On the other hand, higher concentrations of all the elements were
found in corn maize compared to the other plants (leaves and grass). The finding
is in harmony with previous studies [6] where it was attested that maize could
be used as a phytoremediation tool owing to its better ability to bio-accumulate
heavy metals than other plants. The
variations of various heavy metal concentrations in different plant species also
concur with the report of the work on seasonal fluctuations in heavy metal
concentrations in soil and some selected crops[11]. In
this study, elemental concentration in plant species followed the order
F>Zn>Fe>Cr>Cd>Pb. The pattern is analogous to the one observed in the
animal samples, although the concentrations were higher in animal samples than
in all the others, a fact that can be ascribed to ingestion of contaminants
which ultimately causes deposition of these chemical residues in meat [4-5]. It
can be deduced that animals and human beings involved in the food chain could
get exposed to health risks.
Fluoride
levels in animal and plant samples
In the present study,
the high mean concentration of fluoride ion was recorded in sheep meat (9.58±6.03mg/Kg) and goat meat showed a mean level of
6.34±2.45
mg/Kg. The lowest concentration (4.77±2.52mg/Kg) was recorded in leaves. Intake of
fluoride from grass and leaves led to high fluoride in sheep and goats in the
region. The current results were slightly higher than those reported by Kabata and Bendias [20]
who found fluoride concentration in goat meat to range from 0.5 to 5mg/Kg.
Significantly p≤0.05 higher mean concentrations were observed in animals in this
study area in comparison to plants, i.e., leaves, grass, and corn maize. Goats
and sheep meat samples registered higher concentration of fluoride most probably
because of bioaccumulation of the element and also their ability to graze on
different environments which leads to picking of the contaminant from different
sources such as soil, water, grass, and leaves. Other
studies have confirmed that inorganic fluorides tend to accumulate
preferentially in the skeletal and dental hard tissues of vertebrates,
exoskeletons of invertebrates and cell walls of plants [21-34].
Moreover, the study showed that Fluoride concentration was higher in sheep meat
than goat meat probably because sheep usually graze on grasses which are
believed to have high contaminants while the goats browse on leaves. It has been
shown that parts of the plant closer to the soil accumulate the highest amount
of soil as a result of rain drop splash [39]. Therefore, animals grazing on
short plants on fluoride contaminated soils probably ended up ingesting more
fluoride in this manner than did animals grazing on tall plants. Furthermore, differences between animal species concerning magnesium content in
erythrocytes and plasma have been reported
[39]. Sheep
ordinarily have low levels of this element in red blood cells and plasma,
consequently, are more susceptible to fluoride than other mammals
[39]. Leaves had the
lowest concentration of fluoride of all the plant samples studied. This
observation can be supported by the fact that leaves are located high above the
ground, therefore, might not be predisposed to contamination by rain splash
except through absorption from the roots. Elloumi et al. [15] showed that 5 to 10 % of the absorbed fluoride is
transported to the leaves. The total fluoride content of maize
grain was significantly higher than all the plant samples, i.e., leaves and
grass. This could be attributed to its sensitivity to fluoride compared to other
plants [3]. In the present study,
fluoride levels in all the samples studied surpassed the WHO [40] permissible
limit of 1.5mg/Kg. This can be ascribed to the presence of high fluoride levels
in soils and waters around the study area in which fluoride mining and
processing are the predominant operations. These findings clearly show the
possible associated risks and safety of organisms within the food chain
depending on the quantified concentrations of chemicals assayed.
Lead concentrations in plant and animal samples
The lead
concentration was observed in mutton, caprine, leaves,
grass and corn maize. Sheep-meat showed the highest concentration of
0.06±0.02mg/Kg while goat meat had a concentration of 0.06±0.03mg/Kg and corn
maize showed the concentration of 0.04±0.02mg/Kg. The concentrations of lead in grass and leaves were
the lowest as shown in Tables 4, 5 and 6. Similar results were obtained by Akoto et al. [4]
who studied lead and other heavy metal concentrations in liver, kidney, lungs,
brain, heart, and intestine of goat and sheep in a gold mining town in Ghana.
Significantly higher amounts of lead were found in organs of sheep and goat
reared in Kasuwan Shanu
market in Nigeria [5]. The concentration of lead was the lowest in
all the plants (0.01±0.01 mg/Kg in grass and
leaves and 0.04±0.02mg/Kg in corn maize)
compared to other heavy metals owing to the low concentration of the element in
the soil. Also, deposited lead (Pb) is strongly
retained by most soils, resulting in lower plant concentrations compared to more
bio-accessible metals such as cadmium and nickel [23]. Because of the usually
low soil-to-root uptake, the above-ground plant parts are likely to be
contaminated by airborne deposition of lead-containing dust or aerosols onto the
plant surface [22].
Other soil factors such as soil pH, soil nutrients and electrical conductivity
determine lead mobility in the soil to plants [26]. The concentration of lead
among the plant species differed in this study showing that plant species differ
in their ability to accumulate heavy metals. This is consistent with previous
observations by other researchers [26-37]. The results of the study showed that
lead concentrations in all the samples were lower than the permissible limit in the meat of
0.5 mg/Kg [16] and 2 mg/Kg in foods and vegetables [28]. The significance of
this observation is that there is no health risk involved related to lead in
case of consumption.
Cadmium levels in
the samples
The Cd concentration as observed in mutton, caprine and corn maize has been summarized in Tables 4, 5
and 6. The highest Cd concentration was found in goat meat (0.09±0.06mg/Kg) and sheep meat had the concentration of 0.06±0.03mg/Kg. Aranha et al. [7] and Roger et al. [33]
disclosed the cadmium levels in the livers and kidneys of cattle of Poland and
found the cadmium concentration beyond the action level.
The level of cadmium concentration in plants was lower compared to goat meat and
sheep meat. Leaves showed the lowest concentration than grass and corn. This can
be explained by the fact that grass and corn maize are better accumulators of
heavy metals compared to leaves. Vasiliki [39] showed in her study that grass was the
best accumulator of cadmium, copper, iron, manganese, and zinc. Aliyu [6] examined maize and
reported that it could be applied inphyto-remediation
of heavy metals. This indicated the remarkable ability of maize to absorb and
accumulate high concentration of these metals from soil. Cadmium is usually
dispersed in a natural environment through human activities as well as natural
rock mineralization process thus plants can easily absorb cadmium from soil and
transport it into shoot system compared to lead. The results of the studied
samples were within the permissible limit. The allowable limit for cadmium in
the liver has been reported as 0.5 mg/Kg [16]
and maximum permissible level in plants is 2.4 mg/Kg [28]. Therefore, there is
no health risk exposed in case of consumption of such food source in relation to
cadmium.
The
concentration of Zinc in plants and animals samples
The zinc concentrations in all the study samples are shown in Tables 4,
5 and 6. The highest zinc concentration (3.66 ±2.41mg/Kg)
was found in the mutton and lowest concentration (0.26±0.21mg/Kg) in the leaves. From the results, it is shown that the
concentrations of zinc in meat samples (mutton and caprine)
were above the permissible limit (0.3-1.0 mg/Kg) set by WHO and FAO [17]. Zinc
and copper intoxication by industrial emission in the livers, kidneys, spleen,
musculature, ovaries, and uterus of some experimental sheep have been reported
[19]. The study showed that the highest concentration of zinc in the
experimental animals that died of zinc intoxication was in the liver and
kidneys. The high concentration of zinc may be attributed to the presence of
zinc in soils; consequently, the grass and leaves eaten by goats and sheep
contained zinc element. Perhaps, this is one of the reasons for the high level
of zinc in meat. All the plant samples had low levels of zinc compared to the
normal values of about 100 mg/Kg set by WHO and FAO [16]. This may be due to the
relatively low concentration of zinc in the soil. Zinc pollution arises mainly
from atmospheric deposition and could also be derived from vehicular traffic
[12]. Zinc levels can be enhanced in automobile exhausts which may be elevated
near road ways due to wearing out of tyres. The
concentrations of zinc established in the study point out the safety of the food
source; hence there are no health risks anchored.
Iron
concentration in plant and animals in the area
Iron concentration in all the samples studied (mutton, caprine, grass, leaves and corn maize) are summarized in
Tables 4, 5 and 6. The highest concentration (0.82±0.55mg/Kg) was found in sheep meat while the lowest (0.21±0.15
mg/Kg) was in
leaves. The permissible limit of iron in food is 30-150 mg/Kg [14]. A study in
the Kerio Valley revealed the presence of high levels
of iron in Kerio River and its environments which had
0.883 mg/Kg of iron, which is about three times the World Health Organization
(WHO) recommended value of 0.3 mg/Kg [16]. The presence of this element could have led to the accumulation of
plants and animal tissues in the area. The iron
content in the meat samples reported in this study is above the WHO permissible
levels. The maximum permissible level of iron in meat is 0.01mg/Kg [16]. The
meaning of the results is that the food source could be a potential iron-related
health risk.
Chromium
concentration in plants and animals in the study area
The Cr concentration in mutton, caprine,
grass, leaves and corn maize is summarized in Tables 4, 5 and 6. The highest Cr
concentration (0.54±0.33 mg/Kg) was found in the sheep meat and the lowest
(0.19±0.14 mg/Kg) in leaves. The permissible limit for Cr in food is about 0.5
mg/Kg [14]. It was found that the concentration of Cr in the sheep meat exceeded
the permissible limit. This could be attributed to the presence of the
element in the soil [25]. Sheep mostly graze on grasses which are more
bio-accumulators than leaves [39]. Cr is an essential element in helping the body to use sugar,
protein and fat, but it is carcinogenic for organisms
thus excessive amounts may cause adverse health effects [8]. The chromium
contents in all the plant samples were within the normal range of 0.1-0.5 mg/Kg
[10]. The concentration of chromium in all the plant's samples ranged from
0.19±0.14 to 0.23 ±0.18 mg/Kg which is within the normal level attributable to
the low uptake of the metal by plants. Soils contaminated with chromium
generally from sewage sludge, tannery waste, native inorganic chromium in mine
waste are mainly present as Cr (III). Its concentrations in goat meat were within
the permissible limit, and this could be ascribed to the fact that goats mostly
graze on tree leaves which have a low concentration of the element. The results
have aided in availing the necessary information to consumers concerning the
risk status of these food sources.
Assessment of the
levels of analyzed chemical parameters based on sampling locations
The results confirm that
Choff
and Kimwarer recorded levels of Fluoride and heavy
metals that were numerically at par but demonstrated significant differences
(P≤0.05) for cadmium levels (Table 5).On the other hand, Tumeiyo recorded significantly the highest levels of the
chemical parameters tested in this study, while the control location (Turesia) registered the least as was expected since it is
likely to be free from contamination. A similar observation on the significant
difference in elemental concentration based on sampling location was documented
by Achieng et al.
[1] for the lead on soil samples. These findings clearly show that fluorides and
heavy metals contamination within an area of study is subject to a relative
position between the source of the contaminants and the area.
CONCLUSIONS
All the samples studied tested positive to
fluoride and selected heavy metals (Fe, Cr, Zn, Cd, and Pb).
Sheep and goat meat registered higher concentrations of the target analytes which ranged from 0.06±0.02
to 9.58±6.03 mg/Kg compared to plants
(corn maize, leaves, and grass) that contained much lower concentrations ranging
from 0.01±0.01 to 4.77±2.52 mg/Kg. The concentration of fluoride in all the
samples (caprine, mutton, corn maize, grass, and
leaves) exceeded WHO/FAO permissible limits. Statistical analysis showed that
there were significant variations in the levels of the
analyte
in these samples and sampling locations. The high levels of fluoride in the
studied samples could explain the symptoms of fluorosis which were observed in
most animals' and people's teeth inhabiting the study area. The direct
consumption of the leaves, grass, and water by animals from these areas may
result in accumulation of high quantities of fluoride and heavy metals in their
tissues as shown by the findings of the current study. The study recommends that
wastewater emanating from the Fluorspar mining plant in Kerio Valley should be well treated and the pollutants
quantified to reduce environmental contamination. Furthermore, more research
needs to be extended to other areas within the mining plant which have a
hydrological connection.
ACKNOWLEDGMENT
The authors wish to acknowledge the support of
Government Chemist’s laboratory, Nairobi, for some of the analytical work.
1.
Achieng,
G.O., Ongeri, D.M.K. and Omwoyo,
W.N. (2013). Impact of anthropogenic activities on copper and lead
levels in Kisumu city soils. Sky Journal
of Soil Science and Environmental Management, 2(5):47-52.
2.
Adriano, D. C.
& Doner, H. E. (1982). Bromine, Chlorine and Fluorine.
In Methods of Soil Analysis.
American Society of Agronomy. Madison, WI; pp. 449-83.
3.
Ahmad, N.,
Ahmad, S., Zia, A., Shahid, M., Shah, H., Ahmad, M.
and Ullah, S. (2014). Hydrogen fluoride effects on local mung bean and
maize cereal crops from Peri-urban brick kilns in
South Asia. Research report
Fluoride, 47 (4): 315–319.
4.
Akoto, O., Bortey-Sam, N., Nakayama, S. M., Ikenaka,
Y., Baidoo, E., Yohannes, Y.
B., Mizukawa, H. and Ishizuka, M. (2014). Distribution of Heavy Metals in Organs of
Sheep and Goat Reared in Obuasi: A Gold Mining Town in
Ghana. International Journal of
Environmental Science of Toxicology,2 (2):81-89;
P.84-86.
5.
Akan, J. C., Abdulrahman, F. I., Sodipo, O. A &
Chiroma, Y. A. (2010).
Distribution of Heavy Metals in the Liver, Kidney and Meat of Beef, Mutton, Caprine and Chicken from Kasuwan Shanu Market in Maiduguri Metropolis,
Borno
State, Nigeria. Research Journal of
Applied Sciences, Engineering and Technology, 2 (8): 743-748.
6.
Aliyu, H. G. and Adamu, H. M. (2014). The potential of maize as
phytoremediation tool of heavy metals.
European science journal,6 (10):
32-33
7.
Aranha, K., (1994).
Environmental Chemistry. 3rd Edn., New Age International Ltd. Publisher, New Delhi, pp: 213-219.
8.
ATSDR (1999). Toxicological Profile of
Cadmium. Agency for Toxic Substances and Drug Registry, US Department of Health
and Human Services, Atlanta, GA.
9.
Baars, A. J., van Beek, H.,
Spierenburg, T. J., de Graf, G. J., Beeftink, W. G., Boom, J. andPekelder, J. J.
(1987). Fluoride
pollution in a salt marsh: movement between soil, vegetation, and sheep. Bulletin of Environmental Contamination and
Toxicology,39: 945–952
10. Butkus, D. and Baltrėnaitė, E. (2007). Transport of
heavy metals from soil to Pinussyl
vestris L and Betulapendula
trees. Journal of Ecology, 53 (1): 29-36.
11.
Chunilall, V.,
Kindness, A. and Jonnalagadda, S. B. (2005). Heavy
metal uptake by two edible Amaranthus
herbs grown on soils contaminated with Lead, Mercury, Cadmium and Nickel.
Journal of Environmental Science and Health, 40: 375-384.
12.
Conti, M. E.,
Pino, B., and Boca, A. (2008). Lichen Usneabarbata as a biomonitor of
airborne element deposition in the Province of Tierra del Fuego (southern
Patagonia, Argentina)-Ecotoxicology and
Environmental Safety, 72: 1082-1089.
13.
Dalton, A. J. and Malanoski,
J. (1969). Atomic Absorption Analysis of Copper and Lead in Meat and Meat
Products, 52 pp 1035.
14.
Demirezen, O. and Uruc, K. (2006). Comparative study of trace elements in
certain fish, meat and meat products. Food Chemistry, 32: 215-222.
15.
Elloumi, N., Mezghani, I., Ben Abdallah, F., Chaieb, M. andBoukhris, M. (2005).
Fluoride accumulation by vegetation in the vicinity of a phosphate fertilizer
plant in Tunisia. Fluoride, 38 (1):18-24.
16.
FAO/WHO (2011). Summary report of the
seventy-third meeting of JECFA. Joint FAO/WHO Expert Committee on Food
Additives. Geneva.
17.
Geeson, N. A.,
Abrahams, P. W., Murphy, M. P., and Thornton, I. (1997).
Fluorine and metal enrichment of soils and pasture herbage in the old
mining areas of Derbyshire, U.K. Agriculture, Ecosystems and Environment,68:
217-231.
18.
Holding, B. V. (2004). Water treatment and air purification. Lenntech. Rotterdam sewe.
The Netherlands. Pp 58 – 78.
19.
Jozef, B., B. Pavol, H. Miroslav and Biresova, M. (1997). Distribution of risk elements in the
organism of sheep after industrial intoxification
with zinc. Spectrosc. Left., 30: 1263-1277.
20.
Kabata-pendias,
A. and Pendias,
H. (1999). Biochemistry of trace
elements, Ed. PWN, Warsaw, Pp 240.
21.
Kierdorf, H. and Kierdorf, U. (1997).
Disturbances of the secretory stage of amelogenesis in fluorosed deer teeth: a scanning electron-microscopic study.
Cell Tissue Research, 289: 125–135.
22.
McBride M. B. (1998). Growing food crops on
sludge-amended soils: problems with the U.S. Environmental Protection Agency
method of estimating toxic metal transfer.
Environmental Toxicological Chemistry 17 (11): 2274-2281.
23.
McLaughlin, M. J., Parker, D. R. and Clarke,
J. M. (1999). Metals and micronutrients - food safety issues. Field Crops Research, 60 (1-2): 143-163.
24.
Nemade, P. N. and
Shrivastava, V. S. (1996). Radiological skeletal
changes due to chronic fluoride intoxication in Udaipur (dt). Journal for
Environmental Protection, 12 (16):
43- 46.
25.
Nguta, C. M., Osawa, W. O., Onyari J. M. and Onyiego, K. B.
(2010). Levels of Selected Heavy
Metals and Fluoride in Water around Fluorspar Factory in
Kerio
Valley: Kenya. Kenya Journal Science of Technology and Innovation, 1:12-21.
26.
Nouri, J.,
Khorasani, E. N., Lorestani, E. B.,
Karami, E. M., Hassani, A. H. &
Yousefi, E. N. (2009). Accumulation of heavy metals in soil and uptake by
plant species with phytoremediation potential.
Environmental Earth Science, 59:315–323.
27.
Oluyemi, E. A., Feuyit, G. J., Oyekunle, J. A. and
Ogunfowokan, A. O. (2008). International Journal of Environmental
Science and Technology,5 (2):
89 – 96.
28. Opaluwa, O. D., Aremu, M.
O., Ogbo, L. O, Abiola, K.
A., Odiba, I. E., Abubakar,
M. M. and Nweze, N. O. (2012). Heavy metal concentrations in soils,
plant leaves and crops grown around dump sites in Lafia
Metropolis, Nasarawa State, Nigeria. Advances in Applied Science Research,3 (2):780-784.
29.
Orata, F. (2003).
Determination of Heavy Metals in Sediments, Aquatic plants and Fish species from
Lake Victoria. Msc thesis, University of Nairobi.
Pp 25-66.
30.
Osawa, W. O
(2009). Levels of fluoride ion and selected heavy metals and their impact on river
Kimwarer environment in Kerio
Valley- Kenya: MSc thesis Egerton university pp (4, 35-42).
31.
Oskarson, A. L., Jorham, L.,
Sindberg, J., Nilson, N. & Abanus, L. (1992). Lead poisoning in
cattle- Transfer of Lead to milk. Science of the Total Environment, 111:
83-94.
32.
Radostits,
O. M., Gay, C. C., Hinchcliff, K. W., Constable, P. D.
(Ed). (2010). Veterinary Medicine: A Textbook of Disease of Cattle, Sheep, Pig,
Goat and Horses London: W. B. Sanders Harcourt Publishers Ltd; p.1815-1819.
33.
Roga-Franc, M., Kosla, T. and Rokicki, E. (1996).
Cadmium concentration in organs of dairy cows depending on that element contents
in meadow cover. Mengen-Spurenelem., Arbeistag., pp: 393-397
34.
Sands, M., Nicol, S.
and McMinn, A. (1998). Fluoride in
Antarctic marine crustaceans. Marine
Biology, 132: 591–598.
35.
Sami, K. andDruzykli, A. L. (2003). Predicated spatial distribution of naturally occurring arsenic, selenium
and uranium in groundwater in groundwater in South Africa Reconnaissance survey (Report No 1236/1/03).
Pretoria: Water Research Commission.
36.
Shore, R. F. (1995). Predicting cadmium, lead
and fluoride levels in small mammals from soil residues and by species-species
extrapolation. Journal of Environmental Pollution, 88 (3): 333-340.
37. Tsvetkova, E., Bezlova, D., Karatoteva, L., Malinova and Kolev, G. (2012). Assessment of heavy metals and arsenic content in
grasslands of Bulgarka Nature Park. Genetics and
Plant Physiology, 2 (3–4): 161–170.
38.
Turkdogan, M. K., Kulicel, F., Kara, K., Tuncer, I.
and Uyang, I. (2003). Heavy metals in soils, vegetable
and fruit in the endermic upper gastro intestinal
cancer region of Turkey. Environmental, Toxicology and Pharmacology, 13 (3):
175-179.
39.
Vasiliki-Anastasia Anagnostau. (2008). Assessment of heavy metals in central
Athens and suburbs using plant material p 30-35.
40.
WHO (1994). Fluorides and oral health. Report
of a WHO Expert Committee on Oral Health Status and Fluoride Use. Geneva, World
Health Organization (WHO Technical Report Series 846).
