Presentation on theme: "By: Samuel Obiri, Saada Mohammed and Ansa – Asare Osmund (PhD)"— Presentation transcript:
By: Samuel Obiri, Saada Mohammed and Ansa – Asare Osmund (PhD)
Introduction Objectives of the study Concepts of human health risk assessment Methodology Theory/Calculation of the human health risk and socio – economic survey Results & Discussion Conclusion & Recommendation Publication List
E – waste contains numerous toxic or hazardous chemicals that poses significant health hazard to human beings. In Ghana, informal disposal and recycling of e - waste take place, often in small workshops with open burning of plastics and wires, and acid leaching of printed circuit boards.
(1) Determine the concentrations of Pb, Cd, Cr, Cu, As, Sn, Zn and Co in bottom ash and soil samples from areas where e – wastes are openly burnt or dismantled, (2) Assess the cancer and non – cancer human health risks from oral and dermal exposure to the aforementioned toxic chemical in the bottom ash or soil samples by workers involved informal recycling of e - waste. (3) Assess socio – economic perception of e-waste workers using logistic regression.
30 ash samples were randomly collected from 3 places (AGH1, AGH2 and AGH3) where open burning of the e – waste at Agbogbloshie scrap yard. 30 soil samples were also collected from the Agbogbloshie scrap yard. All these samples were transferred into well – labelled plastic containers from September 2012 to March 2013. The samples were collected on bi – weekly basis. 44 questionnaires were admitted to the e – waste workers.
Risk assessment is a process of estimating the probability of the occurrence of an event and the probable magnitude of adverse health effects on human exposures to environmental hazards (Obiri et al., 2013; USEPA, 1989; Kollunu et al., 1996). Human health risk assessment process involves four steps, namely; Hazard identification. Exposure assessment Dose assessment Risk characterization
In this study, the average daily dose (ADD) of Pb, Cd, Cr, Cu, As, Sn, Zn and Co ingested from bottom ash and soil samples in the study area were calculated using: ADD = EPC x IR x FS, B x ED x EF x 10 -6 (1) BW x AT x 365 ADD = Average Daily Dose of the toxicants EPC = Exposure point concentration of the toxicants, e.g. As, Cd, etc in mg/kg IR = Soil/Ash Ingestion Rate in mg/day FS = Fraction of Soil/Ash ingested B = Bioavailability ED Exposure Duration (years) EF = Exposure Frequency (day or years) BW = Body Weight (kg) AT = Averaging Time (Years)
For dermal exposure to As, Cd, Co, Cu, Sn, Cr, Pb and Zn in soil, the ADD is calculated as follows (USEPA, 1999b): ADD = [(EPC x DA x SA x AF x EF x ED)] / (BW x AT)] …. 2 Where: EPC = EPC of As, Cd, Co, Cu, Sn, Pb and Zn in soil/Ash (mg/kg), DA = Dermal Absorption Fraction (unitless), AF = Soil/Ash – skin Adherence Factor (mg/cm 2 ), SA = Skin surface area exposed (cm 2 /day), EF = Exposure frequency (days/years), ED = Exposure Duration (years) BW = Body weight (kg), and AT = Averaging Time (days)
In this study, the following key indicators were used to assess the socio – economic impacts of informal recycling of e-waste: - Safe and healthy working conditions of the workers - Economic viability of e – waste recycling - Impacts on the environment - Working hours
Sample LocationConcentration in mg/kg PbCdCr(V I) CuAsSnZnCo ASH1 5,3882.39427,94020225276123 ASH2 3,2574.58351,1901519527468 ASH3 4,6545.37452,4572532312496 Intervention Level by Lacatusu et al., 2009 1005.0300200--600-
CategoryTotal No. Employed e – waste worker (recyclers + collectors)9,500 – 11,400 Dependents of e – waste workers98,000 – 142,000
CategoryE – waste worker’s earnings Amount in US $Amount in GH Remuneration per month354 – 54211,143.42 – 1,750.66 Remuneration per year4,248 – 6,50413,721.04 – 21,007.92 No. of people employed in informal recycling of e – waste 9,500 – 11,400 Contribution to national economy per year 403,560.00 - 741,456.00 130,349,880 - 239,490,288 Note: 1USD = 3.23 GH
From the results of the study, the following conclusions can be drawn: o High concentration of Pb, Cd, Cr, Cu, As, Sn, Zn and Co were found in bottom ashes of where the e – waste are burnt. The levels of the aforementioned chemicals in the toxic fumes emitted though have not been estimated could pose significant health hazard. o The cancer and non – cancer health risk results in most cases exceeded the acceptable USEPA cancer health risk range of 1 case of cancer out of every 1,000,000 people or to 10,000 people; and hazard quotient value of 1.0.
Further work should concentrate on epidemiological studies to ascertain disease profile of the e – workers at the study area. Levels of the aforementioned toxic chemicals in the toxic fumes from open burning of the e – waste should be measured and the health risk quantified. Government agencies such as the Ghana Health Service and other civil society organisations should team up to educate the workers on the health risk they faced.
Ansa – Asare, O. D., Obiri, S. and Mohammed, S. 2014): Heavy metal contamination in vegetables sold near informal e – waste recycling sites in Ghana. (In Press). Journal of Hazardous materials. Ansa – Asare, O. D., Obiri, S.and Mohammed, S. (2014): Assessment of socio – economic, environmental and human health impacts of informal recycling of e-waste