Environmental exposure to crude oil pollution is associated with under-five morbidity and mortality in Nigeria’s Niger Delta

Abstract Rationale: Crude oil pollution in Nigeria’s Niger Delta has been implicated in persistent environmental degradation and adverse child health outcomes, yet integrated evidence linking exposure gradients to under-five morbidity and mortality remains limited. This study assessed the relationship between crude oil exposure and childhood health burden across Bayelsa, Delta, and Rivers States. Objectives: To evaluate inter-state differences in community awareness, disease prevalence, under-five mortality, and composite health burden indices, and to determine the association between environmental exposure intensity and child health outcomes. Methods: A mixed-methods cross-sectional design was employed across three Niger Delta States. Quantitative data from 975 respondents were analysed using descriptive statistics, chi-square tests, ANOVA, Kruskal-Wallis tests, and regression modelling. Composite indices, including Composite Morbidity Burden Index (CMBI), Composite Mortality Burden Index (CMoBI), Composite Environmental Exposure Index (CEEI), and Overall Burden Index (OBI), were constructed to evaluate exposure-outcome relationships. Results: Awareness of oil spill incidents was uniformly high (Bayelsa 95.1%, Delta 95.0%, Rivers 92.6%). Under-five morbidity was significantly higher in Bayelsa across respiratory (93.9%), dermatological (97.1%), malaria (98.0%), gastrointestinal (91.9%), and ENT conditions (77.1%) (p<0.001). Composite morbidity burden was highest in Bayelsa (91.6%), followed by Delta (82.9%) and Rivers (72.4%) (p=0.002). Mortality burden also differed significantly (Bayelsa 24.2%, Rivers 14.7%, Delta 4.4%; p=0.032). Exposure intensity strongly predicted morbidity (β=0.84, R²=0.71), mortality (β=0.68, R²=0.58), and overall burden (β=0.79, R²=0.66). CEEI showed a clear gradient (Bayelsa 0.95; Rivers 0.79; Delta 0.63), corresponding with OBI differences (57.9%, 43.5%, 43.6%). Mortality attribution varied sharply, with Delta consistently lower across all age groups. Conclusion: Crude oil exposure demonstrates a strong dose-response relationship with under-five morbidity and mortality, with significant spatial heterogeneity across states. Recommendation: Integrated environmental remediation, strengthened primary healthcare systems, and real-time exposure-health surveillance are urgently required in high-burden communities. Significant Health Statement: Crude oil pollution constitutes a major but modifiable determinant of under-five morbidity and mortality in the Niger Delta, with measurable impacts on child survival outcomes.