Job-specific lead exposure gradients and personal protective equipment paradox in informal occupational settings: a case-control study from The Gambia

Background Occupational lead exposure remains a major public health concern in low- and middle-income countries (LMICs), where informal employment structures and weak regulatory oversight create unique exposure patterns. Although auto repair work is recognized as high-risk, within-industry exposure gradients and personal protective equipment (PPE) use patterns remain poorly characterized. This study aimed to assess job-specific blood lead level (BLL) gradients among auto repair workers in The Gambia and examine the relationship between occupational specialty and PPE use. Methods A cross-sectional comparative study enrolled 213 participants in the Greater Banjul Metropolitan Area: 145 exposed auto repair workers (mechanics, electricians, battery repairers, panel beaters/welders, spray painters) and 68 unexposed healthcare worker controls. BLLs were measured using the LeadCare® II system. Questionnaires captured sociodemographic characteristics, work tasks, behavioral factors, and PPE use. Kruskal-Wallis and Mann-Whitney U tests compared BLLs across specialties. Multivariable linear regression estimated adjusted differences in BLL by specialty, and Poisson regression with robust standard errors estimated prevalence ratios for high BLL (≥ 10 µg/dL). Results Exposed workers had significantly higher BLLs than controls (median: 7.40 vs. 5.80 µg/dL; p < 0.001). Within the exposed group, a 5.3-fold gradient was observed: battery repairers (35.62 µg/dL), electricians (15.17 µg/dL), panel beaters/welders (11.45 µg/dL), mechanics (9.08 µg/dL), and spray painters (6.67 µg/dL). All battery repairers (100%) had BLL ≥ 10 µg/dL. Adjusted analyses showed battery repairers had BLLs 27.06 µg/dL higher than mechanics (95% CI: 17.60–36.52; p < 0.001), and electricians had BLLs 6.05 µg/dL higher (95% CI: 1.75–10.35; p = 0.006). A PPE paradox emerged: high-risk specialties (battery repairers, electricians) reported PPE use rates of only 14.3%, compared to 31.8% in lower-risk specialties (p = 0.071). A composite risk score combining smoking, eating at work, no PPE use, and high-risk specialty showed a dose-response relationship with BLL (r = 0.20; p = 0.017). Conclusions Marked within-industry exposure gradients and an inverse relationship between risk and PPE use were identified. Findings underscore the need for targeted, specialty-specific interventions rather than blanket approaches. Battery repair and electrical work should be prioritized for regulatory attention, PPE provision, and health literacy programs in similar low-resource settings.