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

## TL;DR

This study examines how fecal contamination exposure varies in Dhaka's neighborhoods based on human behaviors and environmental factors, highlighting risks for children and the need for targeted interventions.

## Contribution

The study introduces a detailed exposure assessment using the SaniPathTM tool and Bayesian methods to quantify fecal exposure across different urban neighborhoods in Dhaka.

## Key findings

- Children in low-income and floating neighborhoods had more frequent contact with fecal exposure pathways compared to those in high-income areas.
- Contaminated municipal water was the dominant exposure pathway for both children and adults, with higher exposure percentages observed in children.
- Behavioral interventions targeting children and caregivers could mitigate fecal exposure risks and improve public health outcomes in Dhaka.

## Abstract

Poor sanitation and fecal sludge management contribute to fecal contamination in Dhaka’s urban environment. An exposure assessment through ten environmental pathways was conducted using the SaniPathTM tool to understand the exposure to fecal contamination.

Data collection took place from 25/04/2017 to 30/01/2018 in ten neighborhoods: four low-income, four high-income, and two transient/floating neighborhoods. A total of 1000 environmental samples were analyzed using the IDEXX QuantiTray/2000 method with IDEXX-Colilert-24® 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.

Findings 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% of population exposed, either adults or children) 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.

These results highlight substantial risks of fecal exposure across diverse urban settings in Dhaka. Integrated, multisectoral, and sustainable approaches are critical to reduce exposure and protect public health. Behavior change interventions targeting children and caregivers can further mitigate these risks and help ensure long-term public health improvements.