Abstract:
Khat is one of the most consumed plants in the horn of African countries. However, it is a stimulant
plant that has several side effects on the health of consumers. In addition, the fresh Khat (tender
leaves) used for human consumption and the leftover part used as feed for goats and sheep often
contain contaminants such as pesticide residues. The main objective of this study was to determine
the concentrations of selected organochlorine pesticides in chewable and leftover parts of Khat
from the Jimma zone, southwest Ethiopia. A total of 120 Khat leaves were sampled, 60 of which
were chewable and purchased from local markets in Jimma city. The other 60 mature leaves were
leftover Khat samples collected from three predominantly Khat-producing districts in the Jimma
zone. A newly modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method was
used for the extraction of the pesticides from both the chewable and leftover Khat samples. The
method was validated before it was applied. Accordingly, the limit of detection (LOD), limit of
quantification (LOQ), repeatability and reproducibility, and percentage recovery were
determined. Target analytes were determined using GC‒MS. The spiked recovery results for eight
analytes were within the acceptable range of the European Union SANCO. The study revealed that
both the chewable and leftover Khat samples were contaminated by two types of OCPs out of eight
target analytes. Accordingly, p,p’-DDE and p,p’-DDT were detected in 88.3% and 76.6%,
respectively, of the chewable samples and in 86% and 69%, respectively, of the leftover Khat
samples. The concentrations of p,p’-DDE and p,p’-DDT in chewable Khat were in the range of
34.07–45.39 and 11.17–34.15 µg/kg, respectively, and the concentrations of p,p’-DDE and p,p’
DDT in leftover Khat were in the range of 30.12–45.04 and 22.21–32.16 µg/kg, respectively. A
high concentration of the metabolite (p,p’-DDE) compared to the precursor compound (p,p’-DDT)
revealed the historical use of DDT in the study area. The concentrations of pesticides did not vary
significantly between the sample sources (P = 0.823). Among the detected analytes, none were
above the MRL values set by the FAO/WHO or the European Commission (EC). However, the
chewable and leftover Khat available for consumption were contaminated with p,p-DDT and its
principal metabolite p,p-DDE. Thus, the cumulative effect and synergistic toxic effect of these
pesticides on Khat Consumers should be considered. Therefore, all the bodies of concern in the
country need to play the crucial role of ensuring that the Khat consumed by humans and animals
is not a health concern.
