Abstract

Background: Women in the Niger Delta region of Nigeria are exposed to a mixture of toxicants from oil spills, gas flaring and artisanal refining, while women elsewhere in Sub-Saharan Africa (SSA) face lead, cadmium and household air pollution. How these exposures arise, how they combine and what makes some women more vulnerable than others is poorly organised in the literature, which limits what nurses and midwives can do about it.

Objective: To synthesise the types, sources and patterns of cumulative environmental and occupational toxicant exposure reported among pregnant and lactating women in SSA, with emphasis on the Niger Delta, and the factors that modify exposure and vulnerability.

Methods: A systematic review following PRISMA 2020 searched PubMed, Scopus, Web of Science, CINAHL, Global Health, Google Scholar, African Journals Online and grey literature (January 2000 to May 2026). Eligibility was defined using the PECO framework. Two reviewers independently screened studies, extracted data and appraised quality with JBI checklists and the Newcastle–Ottawa Scale. Findings on exposure patterns and effect modifiers were synthesised narratively.

Results: Of 1,898 records, 30 studies were included (12 from Nigeria, two from the Democratic Republic of Congo, two from South Africa, one from Ghana and 13 SSA-wide or global syntheses); 11 were of high, 14 of moderate and five of low quality. Exposure was chronic, multi-route and multi-toxicant. In the Niger Delta it arose from oil spills, gas flaring and contaminated water, soil and food, and involved lead, cadmium, polycyclic aromatic hydrocarbons, volatile organic compounds and particulate matter. In the Democratic Republic of Congo it arose from lead in mining dust and geophagy, and in Ghana and East and Southern Africa from biomass cooking smoke. Biomarker studies found elevated blood lead and cadmium that rose with years of residence, closeness to flares and, modestly, with advancing pregnancy, and metals were detectable in breast milk. Nineteen studies identified effect modifiers: duration and intensity of exposure, trimester, season, occupation, poverty, rural residence, cooking practice and poor nutrition.

Conclusions: Pregnant and lactating women in the Niger Delta and SSA carry cumulative toxicant burdens that are shaped as much by social circumstances, occupation and daily practices as by proximity to pollution. Nurses and midwives can identify high-exposure women through structured exposure histories, counsel on modifiable routes, support breastfeeding mothers and advocate for exposure reduction. Individual-level, longitudinal exposure mixture studies are needed.