Assessment of Risk Connected to the Management of Effluents from Abomey-Calavi and So-Ava Laboratories

Abstract

Aims: This study was conducted to assess the risks connected to effluents released by laboratories performing biomedical analyses in four sanitary training units of Abomey Calavi and Sô-Ava area in Benin. Study Design: It is a transversal and analytical study. Duration of Study: March 2nd to August 31st, 2010. Methodology: The data were obtained based on an observation guide, by interviewing the participants and by analyzing the discharged liquid of laboratories as well as the ground waters (wells, drillings) situated near pits and other places used for discharging biomedical effluents. Results: The results revealed a mismanagement of biomedical effluents. The mean values of pH ranged from 7.17 to 8.83. The conductivity exceeded the acceptable limits in 75% of the cases (2000 to 4260 µS / cm). The COD of sewage rose from 201 to 3400 mg/L and showed strong correlation with the BOD5 (r =0.998) whose values ranged between 150 and 1700 mg/L. The contents in nitrogen (38.4 - 97.5 mg/L) and in phosphates (11.8 to 30 mg/L) exceeded the standards. Besides, significant concentrations of faecal Coliforms exceeding 100x10 UFC / 100mL were recorded in 75 % of the analyzed effluents samples. This explains the ineffectiveness of the decontamination procedure carried out by the laboratory staff. The examination of well waters and water from the drillings situated near pits serving laboratories showed high turbidity (20 to 91,1 NTU), low rates of dissolved oxygen (< 5mg/L) and indications of bacterial contamination (160 UFC of Escherichia coli / 100mL). Conclusion: This study suggests a connection between biomedical activities and groundwater pollution. This issue poses a real problem of public health because of the infectious, toxic and eco-toxic risks for the population and it is important to find an effective solution.