Early-effect biomarkers and hazard index approaches to assessing risks from multiple exposure to metals among battery recyclers in France

Battery-recycling can expose workers to several metals. This study aims to investigate this multiple exposure, by exploring the potential of effect biomarkers to improve risk assessment for workers, and by calculating a hazard index (HI) to assess the risk of cumulative exposure. Urine samples from 86 workers in three French recycling plants were analysed for metal biomarkers (Cd, Co, Cr, Li, Mn, Ni), kidney-injury biomarkers (α1-microglubulin, retinol binding protein, kidney injury molecule-1, N-acetyl-β-D-gluocosaminidase, albumin, total proteins), and oxidative-stress biomarkers (8-hydroxydeoxyguanosine, malondialdehyde). Kidney-injury biomarker levels successfully differentiated exposed recyclers from administrative workers, while oxidative-stress biomarker levels did not allow this differentiation. The calculation of a HI proved effective in detecting the risk associated with multiple metal exposure, offering a better risk assessment than when considering metals individually. This dual approach, combining HI calculation and analyzing kidney-injury biomarkers, should be strongly considered in the risk assessment of workers exposed to multiple metals.