Variation in exposure in neighborhoods of Dhaka, Bangladesh across different environmental pathways: The influence of human behavior on fecal exposure in urban environments

BackgroundPoor sanitation and fecal sludge management contribute to fecal contamination in Dhakas urban environment. An exposure assessment through nine-environmental pathways was conducted using the SaniPath tool to understand the risk of exposure to fecal contamination. MethodsData collection took place from April 2017-January 2018 in ten neighborhoods: four low-income, four high-income, and two transient/floating neighborhoods. A total of 900 environmental samples were analyzed using the IDEXX QuantiTray/2000 method with IDEXX-Colilert-24(R) media for the most probable number (MPN) of E. coli. Additionally, 823 household surveys, 28 community surveys, and 35 school surveys on exposure-related behaviors were conducted. Bayesian methods were used to estimate monthly E. coli exposure levels and population exposure percentages for each environmental pathway in the neighborhoods. ResultsFindings revealed that children (aged 5-12 years) in low-income and floating neighborhoods had more frequent contact with most environmental pathways (at least one-contact per-week or month), except surface water, compared to children in high-income neighborhoods. Dominant exposure pathways varied by neighborhood and socioeconomic status. Children experienced higher estimated monthly fecal exposure doses than adults, primarily through ingestion of contaminated municipal water (all community average=59.2%) and contact with open drains (52.3%) and surface waters (29.0%). Adults were mainly exposed via contaminated municipal water (54.2%), produce (87.0%), and street food (64.5%), which were frequently consumed. ConclusionsThese results highlight significant risks of fecal exposure across diverse urban settings in Dhaka. Integrated, multisectoral, and sustainable approaches are critical. Behavior change interventions targeting children and caregivers can further mitigate these risks and ensuring long-term public health improvements.