Abstract:
Pesticides are applied worldwide to a broad variety of crops to control pests. Different studies in
Ethiopia showed that food products are contaminated with pesticides and banned pesticides are
still being used illegally in the agricultural sector. However, wide uses of these chemicals could
result in food and environmental contamination. This document objectively presents the results
of a study on the determination of organochlorine pesticides (OCPs) residues in tomato and
onion samples collected from selected towns of the Jimma zone. The method used was a
QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method followed by gas
chromatography-mass spectrometry (GC-MS) for analysis. The method was validated for
linearity, limit of detection (LOD), limit of quantification (LOQ), and recovery. The results for
method validation showed that the method was linear over the concentration range of 5-50 ppb
for all eight pesticides tested, with R2 values greater than 0.992. The LOD values for the tested
pesticide ranged from 0.138 μg/kg for P,P'-DDE to 2.400μg/kg for p,p-DDT. LOQ values ranged
from 0.460 μg/kg for p,p-DDE to 8.320 μg/kg for P,P'-DDT. The obtained recovery values
ranged from 74.84% –109.45% except the recoveries of Beta BHC with 67.82%. While most
organochlorine pesticides (OCPs) in onion and tomato samples fell under European Union (EU)
and Codex standards, several exceeded limits. Methoxychlor and P,P'-DDT in onions, and
Methoxychlor, P,P'-DDT, α-BHC, and δ-BHC in some tomatoes, were detected above
permissible levels. Specific OCPs were not detected in certain samples including Aldrin in Meki
Tomato(Mek-T), Gamma-chlordane in Agaro Tomato(Ag-T), and P,P'-DDE in Gera
Tomatoes(Ger-T).Organochlorine pesticides contamination varied across samples. Among
tomatoes, Gera had the highest total OCPs levels (37%), followed by Agaro(34.34%) and
Meki(28.55%). Similarly, Sire onions(SrO) topped the list (28%) compared to Minjer(25.16%),
Shewa robit(25.10%), and Sudan Onion(22.25%).In conclusion, most of the samples of tomatoes
and onions analyzed in this study contained OCP residues and therefore its consumer health risk
assessment is important.
