ABSTRACT
Heavy metal pollution is among the leading health concerns all over the
world because of their long-term cumulative effects. Consumption of
food crops contaminated with heavy metals is a major food chain route
for human exposure. Khat (Catha edulis forsk), a plant used as a
stimulant is grown in certain areas of East Africa and the Arab Peninsula.
In Kenya, it is cultivated in Embu and Meru counties and distributed to
consumers in other counties who include young children. Due to
increased demand and value, many farmers have not only begun growing
it but have also adopted modern farming methods which include
application of fertilizers, pesticides, compost manure, and irrigation. Yet
some of these agricultural practices such as application of fertilizers and
pesticides are known to increase the concentration of heavy metals such
as Cd, Pb, Zn and Cu in the soil. Some of these heavy metals such as Pb
and Cd are toxic even at low concentrations while Zn, Cu, Fe and Cr
though essential in the body, are toxic at high levels. This call for
monitoring to make sure that the levels of heavy metals in khat do not
exceed the threshold limits recommended by WHO due to their adverse
health effects to man. This study therefore determined the levels of Zn,
Cu, Pb, Cd and Cr in khat and in the soils where the plant is grown. Soil
and khat samples were collected from the three main khat growing
regions namely Embu, Mbeere and Nyambene. Known weights of oven
dried khat and soil samples were digested using nitric and perchloric
acids. The digests were analysed for selected heavy metals using flame
atomic absorption spectrophotometer. The following concentration
ranges in dry weight (μg/g) were obtained in khat: Zn(25.15-73.95),
Cu(0.10-41.80), Cr(ND-39.50), Cd(ND-0.90) and Pb(0.50-13.00). Cd
was only detected in khat samples from Embu. In soil, the concentrations
of selected metals in dry weight (μg/g) were as follows: Zn(25.50-
440.30), Cu(0.65-54.40), Cr(7.50-170.50) Cd(0.05-1.40) and Pb(5.00-
119.00). Levels of these metals in soil were below the permissible limits
for agricultural land use set by FAO/WHO. Correlation study revealed
positive correlation between metals in soil and khat except for Zn, Cu
and Pb in Embu. The ANOVA results suggested that there was
significant different (p 0.05) in the levels of heavy ˂ metals between khat
from various regions. Levels of studied heavy metals in khat were below
the maximum limits recommended by WHO except for Pb and Cr.
Therefore children should be discouraged from chewing khat since they
are more susceptible to adverse effects of Pb than adults.
Ireri, S (2021). Determination Of The Levels Of Selected Heavy Metals In Soil And In Khat (Catha Edulis Forsk) Grown In Kenya. Afribary. Retrieved from https://afribary.com/works/determination-of-the-levels-of-selected-heavy-metals-in-soil-and-in-khat-catha-edulis-forsk-grown-in-kenya
Ireri, Sailus "Determination Of The Levels Of Selected Heavy Metals In Soil And In Khat (Catha Edulis Forsk) Grown In Kenya" Afribary. Afribary, 01 Jun. 2021, https://afribary.com/works/determination-of-the-levels-of-selected-heavy-metals-in-soil-and-in-khat-catha-edulis-forsk-grown-in-kenya. Accessed 09 Oct. 2024.
Ireri, Sailus . "Determination Of The Levels Of Selected Heavy Metals In Soil And In Khat (Catha Edulis Forsk) Grown In Kenya". Afribary, Afribary, 01 Jun. 2021. Web. 09 Oct. 2024. < https://afribary.com/works/determination-of-the-levels-of-selected-heavy-metals-in-soil-and-in-khat-catha-edulis-forsk-grown-in-kenya >.
Ireri, Sailus . "Determination Of The Levels Of Selected Heavy Metals In Soil And In Khat (Catha Edulis Forsk) Grown In Kenya" Afribary (2021). Accessed October 09, 2024. https://afribary.com/works/determination-of-the-levels-of-selected-heavy-metals-in-soil-and-in-khat-catha-edulis-forsk-grown-in-kenya