Levels of Some Heavy Metals in the Leaves of Henna Plant (Lawsonia inermis) within Lamu County, Kenya

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Date
2020Author
Mohammed, Tsanuo Kassim
Ochieng, Jaleny Paul
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Henna plant scientifically known as Lawsonia
inermis is an ethno botanical plant used majorly
for preparation of dye called henna. The plant
contains a pigment called Laws one which
makes it suitable for preparation of henna used
in painting or beautification of body parts.
Henna painting of body parts is an art of
beautification which is commonly practised by
the people of Lamu County and other parts of
the world. However, high levels of toxic heavy
metals such as lead (Pb), Cadmium (Cd) and
Nikel (Ni) commonly found in henna products
pose health threat to users. One of the sources of
heavy metals in cosmetic henna products is the
henna leaves. The aim of the study was to
determine the level of heavy metals; Lead (Pb),
Cadmium (Cd) and Nickel (Ni) in henna leaves
within Lamu County in order to assess their
suitability as raw material for henna products
with respect to the international standard limits.
A total of 60 henna leaf samples were randomly
selected from Mpeketoni, Amu, Pate and
Kiunga sampling sites within Lamu County and
analysed for heavy metals using Flame Atomic
Absorption Spectroscopy (FAAS) after acid
digestion of the samples. Analysis of variance
(ANOVA) using SPSS version 17.0 was used to
analyse the data. The least and highest mean
levels (ppm) of heavy metals in the henna leaf
samples were as follows: Pb (0.04±0.01 to
0.93±0.04), Cd (0.01±0.00 to 0.09±0.01) and Ni
(0.01±0.00 to 0.34±0.02). The pattern of overall
mean level of heavy metal accumulation in the
henna leaves followed the order: Pb > Ni > Cd.
No significant difference in the overall mean
level of lead (p=0.155), cadmium (p=0.577) and
nickel (p=0.355) in the henna leaves was noted.
Among all the sampling sites, a significant
difference in the level of nickel (p=0.021) was
recorded only within Mpeketoni site. From the
results of the study, it showed that henna leaves
from Lamu County formed a good raw material
for henna products due to their low level of lead,
cadmium and nickel in comparison to the
standard limits by WHO. Effective quality
control measures, proper selection of raw
material as well as good manufacturing practises
should be enhanced so as to minimise the levels
of these metals in henna products.