Occupational Exposure to Endotoxin along a Municipal Scale Fecal Sludge Collection and Resource Recovery Process in Kigali, Rwanda

Rachel Sklar, Zeyi Zhou, Marley Zalay, Ashley Muspratt and S. Katharine Hammond
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Rachel Sklar: Environmental Health Sciences Division, School of Public Health, University of California, Berkeley, CA 94720, USA
Zeyi Zhou: Environmental Health Sciences Division, School of Public Health, University of California, Berkeley, CA 94720, USA
Marley Zalay: Office of Environmental Health Hazard Assessment, Oakland, CA 94612, USA
Ashley Muspratt: Independent Consultant, Northampton, MA 01060, USA
S. Katharine Hammond: Environmental Health Sciences Division, School of Public Health, University of California, Berkeley, CA 94720, USA

IJERPH, 2019, vol. 16, issue 23, 1-11

Abstract: Background : Little is known about occupational exposures that occur along fecal sludge collection and resource recovery processes. This study characterizes inhaled endotoxin exposure to workers of a municipal scale fecal sludge-to-fuel processes in Kigali, Rwanda. Methods : Forty-two task-based air samples were collected from workers in five tasks along the fecal sludge collection and resource recovery process. Samples were processed for endotoxin using the limulus amebocyte lysate (LAL) test. To account for exposure variability and compare measured concentrations to established exposure limits, we used Monte Carlo modeling methods to construct distributions representing full eight-hour (8-h) exposures to endotoxin across eight exposure scenarios. Results : Geometric mean (GM) endotoxin concentrations in task-based samples ranged from 11–3700 EU/m 3 with exposure concentrations increasing as the dryness of the fecal sludge increased through processing. The thermal dryer task had the highest endotoxin concentrations (GM = 3700 EU/m 3 ) and the inlet task had the lowest (GM = 11 EU/m 3 ). The geometric means (GM) of modeled 8-h exposure concentrations were between 6.7–960 EU/m 3 and highest for scenarios which included the thermal dryer task in the exposure scenario. Conclusions : Our data suggest the importance of including worker exposure considerations in the design of nascent fecal sludge management processes. The methods used in this study combine workplace sampling with stochastic modeling and are useful for exposure assessment in resource constrained contexts.

Keywords: occupational exposure assessment; endotoxin; fecal sludge management; sanitation; Rwanda; mathematical modeling (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2019
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