Environmental nuisance exposure mediates the relationship between abattoir proximity and household enteric dermatological morbidity: a GPS-anchored cross-sectional study in Bo and Kenema Cities, Sierra Leone

Abstract

Background Urban abattoirs across sub-Saharan Africa commonly operate within residential neighborhoods(Adeniyi et al. 2025), exposing surrounding households to odor, effluent, vectors and noise(Ibegbu et al. 2024). The community-health consequences are poorly quantified in Sierra Leone, and the common assumption that harm is a direct function of physical distance has not been tested against measured exposure. We assessed whether environmental nuisance exposure mediates the relationship between abattoir proximity and household enteric–dermatological morbidity in Bo and Kenema Cities. Methods We conducted a community-based analytical cross-sectional study among 950 residents (Bo = 497; Kenema = 453) living around confirmed abattoirs, using a GPS-enabled questionnaire. A five-item nuisance exposure index was constructed (Cronbach’s α = 0.802), and metric distance to the nearest abattoir was computed from field coordinates. We used multivariable logistic regression and a bootstrapped causal-mediation analysis (5,000 resamples), with malaria/vector-borne illness as a pre-specified negative-control outcome. Results Nuisance exposure declined monotonically with distance (Spearman ρ = −.40, p < .001) and independently predicted enteric dermatological morbidity (adjusted OR ≈ 1.24 per index point; p < .001). Distance had no independent association with morbidity once exposure was included. Mediation analysis showed that abattoir proximity influenced enteric–dermatological morbidity entirely through nuisance exposure (natural indirect effect = -0.31, 95% CI \[-0.45 to -0.21\]; direct effect non-significant), indicating complete mediation. In contrast, malaria rose with distance (OR ≈ 1.6; p = 0.006), the opposite direction, arguing against generalised deprivation as a confounder. Conclusions The health burden of urban abattoirs in this setting is driven by measurable environmental nuisance load rather than physical distance, with exposure completely mediating the proximity morbidity relationship. Interventions should prioritise nuisance abatement effluent control, waste management and vector control over relocation alone.