Haematological investigation of arsenic and lead exposure burden in adult human population at the Gangetic Plains of Bihar, India

Bihar, a densely populated region in eastern India, faces significant public health challenges due to environmental contamination by heavy metals. Arsenic (As) and lead (Pb) are persistent toxicants known to adversely affect multiple physiological systems. This study assessed blood As and Pb concentrations and their associations with haematological parameters among adults residing in thirteen districts of Bihar. A cross-sectional biomonitoring study was conducted on 1279 adults, around rural and semi-urban populations. Mean blood As and Pb concentrations were 41.86 and 369.19 µg/L, respectively, indicating widespread exposure. Haematological assessment revealed a high prevalence of abnormalities, including low red blood cell counts (42.7%), anaemia (30.3%), leukopenia (20.9%), and thrombocytopenia (41.8%). Pearson correlation analysis demonstrated a statistically significant negative association between blood As levels and white blood cell counts (r = − 0.064, p = 0.023) as well as platelet counts (r = − 0.108, p < 0.001), suggesting potential immunotoxin and haematotoxin effects of arsenic exposure. In contrast, although blood lead levels were markedly elevated, no significant associations were observed with haematological markers. District-level analysis revealed higher As concentrations in Patna and Vaishali, while elevated Pb levels were observed in Darbhanga and Arwal. These findings highlight extensive internal exposure to As and Pb in Bihar, with arsenic showing measurable adverse effects on immune and haematopoietic parameters. The study underscores the urgent need for routine biomonitoring, access to safe drinking water, and strengthened regulatory measures to mitigate As and Pb exposure in Bihar.