# Assessing E. coli levels in surface soils of informal settlements using boot sock and standard grab methods

## TL;DR

This study compares two soil sampling methods to detect E. coli in informal settlements, finding that the boot sock method is more effective and efficient.

## Contribution

The boot sock method is introduced as a more sensitive and spatially representative technique for detecting fecal contamination in informal settlements.

## Key findings

- The boot sock method detected E. coli more sensitively than traditional grab sampling.
- Boot sock sampling showed lower inter-replicate variation compared to grab samples.
- Fewer samples are needed with the boot sock method to achieve adequate spatial representation.

## Abstract

Rapid urbanization leads to the growth of informal settlements, where inadequate sanitation infrastructure is common, thus promoting environmental contamination and risk of gastrointestinal infection. Soil contamination contributes to the transmission of enteropathogens, but traditional sampling approaches may poorly indicate public health risks due to limited spatial representation. This study compares traditional grab sampling of soil with a boot sock method, a composite technique designed to better reflect human-pathogen interactions. The boot sock method provided more sensitive detection of E. coli and lower inter-replicate variation compared to grab samples. Post hoc power analyses indicated that the boot sock technique required fewer samples to achieve adequate spatial representation across a sampling area than grab samples, potentially improving time and cost efficiency in pathogen exposure risk estimation.

Boot sock sampling is an informative and valuable approach to assessing soil fecal contamination in informal settlements.