Field-calibrated threshold-distance assessment of lead dispersion from controlled lead-acid battery plate combustion

Controlled burning of lead-acid battery plates can release lead-bearing particulate matter that disperses through the air, deposits on passive surfaces, and is transferred to edible crops. This study quantified the source-to-receptor pathway under field-calibrated conditions in Kushtia, Bangladesh, by monitoring PM_2.5 and PM₁₀ across a triangular sampling grid extending to 45 m, assessing passive Pb deposition on Whatman filter papers, and measuring Pb accumulation in red amaranth (Amaranthus tricolor L.). Three battery plates were burned per event, producing an approximate total mass loss of 149.7 ± 4.5 g. PM, deposition, and crop data all exhibited strong distance-dependent gradients, and two-way ANOVA represented significant effects of distance, time/week, and their interaction for all response variables (all p < 0.0001). PM_2.5 showed the strongest distance-dependent association with both filter-paper Pb deposition and Pb accumulation in red amaranth within the sampled range, while PM₁₀ showed significant but weaker associations within the sampled distance range. The background control plot remained below the instrumental detection limit, supporting atmospheric deposition as the dominant exposure pathway. The crop-response model showed an excellent fit (R² = 0.948), since the Codex leafy-vegetable Pb benchmark is based on fresh weight while plant data were measured on a dry-weight basis, the threshold distance was evaluated across a plausible moisture range. Therefore, the 50 m setback is presented as a precautionary recommendation rather than a strict model-derived boundary. The findings provide a mechanistic basis for setback planning around informal battery-burning activities and highlight the food-safety risks of atmospheric Pb transfer to edible crops.