Assessment of organochlorine pesticide residues in blood and placenta tissues of mothers living in Kanungu District and Kampala Capital City

Abstract

This study determined the levels of organochlorine pesticides in blood and placenta tissues of mothers from Kanungu District (N=26) and Kampala Capital City (KCC) (N=26). Samples for Kanungu District were collected from Kambuga hospital while those for KCC were collected from Nsambya hospital. Extraction and clean- up was done using solid phase and florisil method, respectively. Analysis of extracts was done using the GC-ECD and GC-MS for confirmation. Samples were considered positive when their residue levels were greater than or equal to the limits of detection (LOD). The LOD (ng g-1) were: p,p′-DDT (0.06), p,p′-DDE (0.3), o,p′-DDE (0.05), p,p′-DDD (0.07), o,p′-DDD (0.09), aldrin (0.1), dieldrin (0.06), lindane (0.2), α-endosulfan (0.2) and β-endosulfan (0.05). The mean recoveries of the detected residues varied from 67.0 to 80.0 % and 75.0 to 88.0% in blood samples at spiking levels of 0.4 and 1.0 ng g-1, respectively, where as for placenta tissues it ranged from 69.0 to 78.3% at 0.4 ng g-1 and 77.3 to 87.0% at 1.0 ng g-1. Since most recoveries were above 60%, residue levels have not been corrected for recovery. The ΣOCPs was 425.46 and 65.28 ng g−1 l.w in blood samples from Kanungu District and KCC, respectively. The high levels of OCPs for Kanungu District could be attributed to their past use for agricultural and public health activities. o,p′-DDE was the most predominant metabolite of DDT in all the blood samples (contributed 36% to the ΣDDTs in Kanungu District and 40% in KCC). Levels of dieldrin and α-endosulfan were in the range n.d-5.10 ng g−1 l.w and 39.67-88.44 ng g−1 l.w, respectively in blood samples from Kanungu District where as those for Kampala Capital City were 1.73-4.25 ng g−1 l.w and n.d-11.30 ng g−1 l.w for dieldrin and α-endosulfan, respectively. Aldrin, lindane and β-endosulfan were not detected in all the blood samples analyzed. The presence of α-endosulfan and the absence of β-endosulfan in this study indicate recent input or lack of significant degradation of technical endosulfan. However, detection of epoxide analogue dieldrin and the absence of aldrin in the blood samples suggests past input of aldrin. In placenta tissues, DDTs were detected up to levels of 133.86 and 33.67ng g−1 l.w for Kanungu District and KCC, respectively. The ratio p,p′-DDE/p,p′-DDT for placenta tissues from Kanungu District was greater than 1, suggesting past input of technical DDT. Aldrin was detected in 69% of the samples from Kanungu District at a mean level of 4.50 ng g−1 l.w higher compared to dieldrin (4.29 ng g−1 l.w), indicating recent input of aldrin in the environment. The study also detected β-endosulfan however, no traces of α-endosulfan were detected in all the placenta tissues. This could be attributed to past input of technical endosulfan moreover endosulfan was banned for use in 2012. The demographic characteristics showed a positive and negative correlation of levels of OCPs with the age of mothers and increase in the number of births, respectively. It was concluded that higher levels of OCPs were in blood and placenta tissues of mothers who majorly consumed food of animal origin.