Organochlorine pesticides in honey and soils from areas surrounding an abandoned store at Masindi District, Western Uganda
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This study determined the concentrations of organochlorine pesticides (OCPs) in soil and honey from areas surrounding an abandoned store at the Masindi District Headquarters. The samples were extracted using solid-liquid extraction method while clean-up was done using the florisil method. The analysis of sample extracts was done using a Gas Chromatography (GC) equipped with an Electron Capture Detector (ECD), while confirmation was performed on a GC - Mass Spectrometer (MS) coupled to a GC. Samples were considered positive when their levels were greater than the limit of detection (LOD). The LODs of pesticides in µgkg-1dry weight (d.w) were, p,p′-DDT (0.05), o,p′-DDE (0.05), p,p′-DDE (0.04), p,p′-DDD (0.08), o,p′-DDD (0.09), aldrin (0.07), dieldrin (0.10), α-endosulfan (0.20), β-endosulfan (0.04), and lindane (0.10). The recoveries of the detected analytes ranged from 64 to 90%and 73to 99% for soil and honey, respectively. Total (Σ) concentrations of DDT and metabolites in soil varied from 83.2 to 1665 µg kg-1 d.w. The concentrations of ΣDDTs at site A was significantly higher compared to other sites, this could be due to the fact that it’s nearer the store. o,p'-DDD was the most predominant DDT isomer(contributed >35% to the ΣDDTs), suggesting past deposits of technical DDT in the soil which could have been degraded by sunlight and bacteria. The ratios of p,p′-DDE/p,p′-DDT ranged from 1.0 to 2.8 (mean 2.0), confirming past input of DDT and/or related compounds in areas surrounding the Masindi District Headquarters. This study also detected other OCPs in soil at concentration ranges of 7.70-12.0 µg kg-1 d.w (lindane), 7.6-118 µg kg-1 d.w (dieldrin) and 2.40-13.5 µg kg-1 d.w (α-endosulfan). The presence of dieldrin and the absence of aldrin in soil samples suggests past application/ transport of aldrin that could have degraded to dieldrin in the Masindi environment. The ΣOCPs in honey were between 20.2 and 107 µg kg-1wet weight (w.w). The levels of OCPs in honey decreased as the distance from the abandoned pesticide store increased. It was observed that hive 1 had OCP concentrations that were statistically higher than the other hives. The high concentrations of pesticides in hive 1 could be attributed to its closeness to the store. The ΣDDT in honey varied from 2.36 to 33.2 µg kg-1 w.w. o,p'-DDD and o,p'-DDE were the most predominant metabolites of DDT, (contributed 63 to 22% to the ΣDDTs, respectively). Other OCPs detected in the honey were lindane (n.d. – 40.9 µg kg-1 w.w), dieldrin (0.39 – 4.86 µg kg-1 w.w), α-endosulfan (5.20– 25.5 µgkg-1 w.w) and β-endosulfan (n.d. – 7.16 µg kg-1 w.w). The ratio of α-/β-endosulfan ranged from 1.2 to 3.6 (mean 2.4), suggesting recent application of endosulfan. In majority case, Estimated Dietary Intake (1.3×10-4, 1.1×10-4,18.6×10-4, 10.7×10-4, 53.4×10-4, 7.10×10-4, 41.8×10-4, 9.00×10-4and 58.9×10-4 µg/kg bodyweight/day for p,p′-DDT,p,p′-DDE, o,p′-DDE, p,p′-DDD, o,p′-DDD, dieldrin, α-endosulfan, β-endosulfan, and lindane, respectively) were a lower than the Acceptable Dietary Intake (10, 10, 10, 10, 10, 0.1, 7.5, 7.5 and 5.0). Hazard index (HI) values for detected pesticides were <1, indicating the consumption of honey from areas surrounding the store was of minimal health risks.