Assessment of Pathogen exposure routes associated with the processing ans use of Sludge from the Lubigi sewage and faecal sludge treatment plant.

Abstract

This report describes an assessment of the pathogen exposure pathways as a component study of the Quantitative Microbial Risk Assessment (QMRA) associated with the processing and reuse of faecal sludge from the Lubigi Sewage and Faecal Sludge Treatment plant. This study focused on the first two steps of the QMRA, i.e., hazard identification, and exposure assessment, and characterized the risk only in a qualitative manner. Data was collected through observations, interviews and a comprehensive literature review, which also informed the analysis to be performed. The results suggested that the current management practices were inadequate for all At Risk Persons (ARPs). All three exposure pathways i.e. dermal contact, inhalation and ingestion were evident along the entire FSM chain under study and manifested under normal working conditions and accidents. Dermal contact and inhalation were prominent with two identified accident events each. The cesspool offload area had three out of the five identified accident events for all three pathways. Ingestion was impacted upon by workers eating at any location within the S&FSTP. The ingestion pathway was aggravated by not wearing gloves and lack of soap at hand washing stations. The current health risk barriers were insufficient or failing due to lack of consistency and enforcement on their use. The most used health risk barrier was PPE especially overalls and gumboots by all the ARPs. In conclusion, most of the stakeholders were unaware of the risk events and paid little caution to poor management practices. High risk events took up 35.29% of all identified risk events. Medium risk events took up 58.82% while 5.88% were low risk. In terms of recommendations, majority of the high risk events were related to dermal contact hence strict regulations should be put in place on compliance to wear gloves. Farmers who use FS as a fertilizer especially tomato farmers should resort to using drip irrigation as opposed to using hoses during irrigation. Consumers should wash well all produce to eliminate chances of dermal contact and accidental ingestion of residue FS on the surfaces of produce and should cook all produce and not eating tomatoes raw. Further studies are recommended to focus on QMRA for the cesspool emptier truck personnel; and a study involving quantitative chemical risk assessment of reuse of FS in agriculture should be performed.