An experimental study was conducted to assess the pathogen removal efficiency of primary treatment of ecological sanitation (eco-san) system. Ash, lime and soil were used as covering and treatment materials of faeces in the system. A significant rise in pH was observed when the faeces were treated with lime and ash, with a pH value of 11.3 and 9, respectively. Lime treatment was effective in complete destruction of faecal coliforms within 24 h while ash treatment took 30 days of storage to give the same result. On the other hand, no immediate destruction of Ascaris ova was observed during primary treatment of eco-san faeces. Dehydration and storage were other parameters which were considered in the experiment. Faecal coliforms tolerated a moisture content of 3% in untreated faeces while a large number of Ascaris lumbricoides eggs were inactivated by the same level of desiccation, even in the absence of alkaline treatment. The study showed a strong direct relationship between moisture content and viability of Ascaris egg (r = 0.806, p = 0.01) and a negative correlation between viability of eggs and storage time (r = -0.895, p = 0.01). Generally, the treatment methods used in this experiment showed a substantial potential of faeces sanitization, with removals ranging from 54 to 100% after a minimum of 40 days storage.
Exposure to lead (Pb) through drinking water has been linked to adverse health outcomes. Children are particularly susceptible. This study was designed to measure Pb contamination level in drinking water of the Ethiopian city Addis Ababa and assess the associated health risks. Eighty-eight fully-flushed drinking water samples were collected from all ten sub-cities of Addis Ababa. Pb concentration was measured using an Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The chronic daily intake (CDI), the hazard quotient (HQ), and the cancer risk (CR) of Pb were determined to assess exposure levels and health effects. Blood lead level (B-Pb) for children was modelled using the integrated exposure uptake biokinetic model (IEUBK). The mean concentration of Pb in the drinking water was 17.8 μg/l, where >50% of the samples exceeded WHO's 10 μg/l guideline. Significant spatial variation of Pb was noticed among sub-cities. The mean CDI was 1.43 and 0.59 μg/kg/day for children and adults, respectively. The HQ showed that 8% of children and 2.3% of adults exceeded the safe limit. The predicted geometric mean of B-Pb ranged from 3.23 to 14.65 μg/dl. The risk of a child having a B-Pb level >5 μg/dl at the median water Pb concentration (10.5 μg/l) was estimated at 13.4%. Based on the 95 th percentile Pb concentration (75.1 μg/l), 89.6% of children would have B-Pb levels above the 5 μg/dl threshold. The estimated CR was found in the range of 1 Â 10 À7 to 9.9 Â 10 À5 ; hence cancer risks are not a concern. The study concluded that Addis Ababa's drinking water is likely to be a source of lead exposure where consumers at specific city locations are at risk of numerous non-cancer health effects. The impacts are expected to be severe in the Ethiopian context; hence further investigations and coordinated interventions are required.
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