Organochlorine pesticides in mothers' breast milk and risk assessment posed to nursing infants in Kanungu District and Kampala District

Abstract

This is the second study to report organochlorines (OCPs) in maternal breast milk in Uganda. The main aims of the present study were to determine concentrations of selected organochlorine pesticides in mothers’ breast milk and assess risks posed to nursing infants in Kanungu district and Kampala district. The breast milk samples were collected from a total of 52 lactating mothers of whom 26 had lived in Kihiihi sub-county Kanungu District for at least 3 years and 26 samples from Kampala District. The samples were extracted using the solid phase and clean-up was done using the florisil method. The analysis of sample extracts was done using a gas chromatograph (GC) equipped with an electron capture detector (ECD) and confirmation was done on a mass spectrometer (MS) coupled to a GC. Samples were considered positive when their residue levels were greater than limits of detection (LOD) in ug kg-1. The recoveries of detected analytes varied from 67 to 88%, and since recoveries were above 60%, data was not corrected for recovery. Total (Σ) concentrations of DDT and metabolites was 50 ug kg-1 l.w for samples from Kihiihi Kanungu District and 19 ug kg-1 l.w for samples from Kampala District. The concentration of DDT and metabolites in breast milk samples from Kihiihi sub-county were significantly higher compared to those from Kampala District. p,p′-DDE was the most predominant metabolite in samples from Kihiihi (contributed 58 % to the ΣDDTs) and Kampala 63 % to the ΣDDTs). Other OCPs in breast milk samples from Kihiihi recorded were lindane from non detectable levels (n.d) to 19 ug kg-1 l.w), aldrin (n.d. – 9 ug kg-1 l.w), dieldrin (n.d.– 130 ug kg-1 l.w), -endosulfan (n.d.– 9 ug kg-1 l.w) and endosulfan-sulfate (n.d.– 17 ug kg-1 l.w). On the other hand, samples from Kampala recorded the mean concentrations as 4, 1, 10, 2 and 3 ug kg-1 l.w for lindane, aldrin, dieldrin, endosulfan and endosulfan-sulfate, respectively. The demographic characteristics showed that the levels of OCPs increased with mothers’age, but decreased with the number of births. Estimated Daily Intake (EDIs) in ug kg-1 body weight/day for nursing infants from Kihiihi sub-county were 0.05 (p,p′-DDT), 0.122 (p,p′-DDE ), 0.013 ( o,p′-DDE), 0.025 (p,p′-DDD), 0.017 (α-endosulfan ), 0.021 (endosulfan-sulfate ), 0.008 (aldrin), 0.110 (dieldrin ) and 0.025 (lindane). The EDIs for Kampala District were lower than those of Kihiihi sub-county, and in both study areas, the EDIs were lower than the acceptable daily intakes (ADIs) of 10, 10, 10, 10, 6.0, 6.0, 0.1, 0.1 and 5.0 ug kg-1 body weight/day for p,p′-DDT, p,p′-DDE, o,p′-DDE, p,p′-DDD, α-endosulfan, endosulfansulfate, aldrin, dieldrin, lindane respectively, set by the FAO/WHO Codex Alimentarius Commission (2006). In general, Hazard Quotients (HQs) were less than one, indicating that breast milk was of minimal health risks to the nursing infants.