Background: Occupational exposure to lead remains a significant public health concern, particularly among fueling station attendants who are routinely exposed to petroleum products. Chronic lead exposure has been associated with alterations in haematological indices and impairment of immune function.

Objective: This study evaluated the effect of blood lead levels (BLL) on selected haematological parameters and CD4+ T-cell counts among fueling station attendants in Jigawa State, north-western Nigeria.

Methods: A comparative cross-sectional study was conducted among 378 apparently healthy adults aged 18 years and above, recruited using purposive sampling. Venous blood samples were collected for determination of full blood count (FBC), blood lead levels, and CD4+ T-cell counts. Haematological parameters were analyzed using a Sysmex KN-21 automated haematology analyzer, CD4+ counts were determined using the Partec CyFlow system, and blood lead levels were measured using a Shimadzu 6800 Atomic Absorption Spectrophotometer. Data were expressed as mean ± standard deviation. Group comparisons and Spearman’s correlation analysis were performed to evaluate associations between BLL and the measured variables, with statistical significance set at p < 0.05.

Results: Blood lead levels were significantly higher among fueling station attendants than in the control group (p = 0.001). Total white blood cell count, mixed cell percentage (MXD%), lymphocyte percentage (LYM%), and red cell distribution width (RDW) were significantly elevated among exposed participants (p < 0.05). In contrast, neutrophil percentage (NEUT%), red blood cell count (RBC), haemoglobin (Hb), haematocrit (HCT), mean corpuscular haemoglobin concentration (MCHC), mean corpuscular volume (MCV), and mean corpuscular haemoglobin (MCH) were significantly reduced (p < 0.05). Blood lead levels showed significant positive correlations with lymphocyte and neutrophil counts, while a significant negative correlation was observed with MXD%. Haemoglobin, haematocrit, mean corpuscular volume, and neutrophil counts declined significantly with increasing blood lead levels, whereas lymphocyte counts increased significantly. CD4+ T-cell counts were also significantly lower among fueling station attendants than among controls (p < 0.05).

Conclusion: Elevated blood lead levels among fueling station attendants are associated with significant alterations in haematological indices and reduced CD4+ T-cell counts, suggesting that chronic occupational lead exposure may adversely affect both haematopoietic and immune functions. Routine biological monitoring and implementation of effective occupational health and safety measures are recommended to minimize lead exposure in this population.

Keywords: Blood lead level, fueling station attendants, haematological parameters, CD4+ T cells, occupational exposure, Nigeria.