Pollution estimation and health risks assessment related to the agricultural application of mussel shell-derived chitosan as organic amendment

In this study, estimation of pollution and assessment of health risks related to the agricultural application of mussel shell–derived chitosan as organic amendment were evaluated. Furthermore, considering WHO maximum permissible levels in soil, the application rates of chitosan to agricultural soils were calculated. Geo-accumulation index (I_geo), enrichment factor (EF), contamination factor (CF), pollution load index (PLI), and ecological risk index (ERI) were calculated. Mussel shell-derived chitosan generally did not contribute to soil metal loading when evaluated in terms of those indices. The highest hazard quotient for ingestion (HQ_ing) across male (ML), female (FML), and children (CL) followed the order Cr > Ni > Mn >Pb >Zn >Cu, while maximum HQ_ing among metals was observed in the order CL > FML > ML. For inhalation exposure, highest HQ_inh for all metals was also found in the order CL > FML > ML, with individual metal contributions following Mn > Ni > Cr >Zn >Pb >Cu. Maximum HQ_der exhibited the trend ML > FML > CL, and the metal-specific order for HQ_der was Cr > Pb > Ni >Zn >Mn >Cu. Hazard Index (HI) and Total HI for ingestion, inhalation and dermal exposure were all less than 1. Cancer risk was less than 1 × 10⁻⁶. Consequently, there were no pollution and health risks associated with the use of musselshell‑derived chitosan in agriculture as organic amendment.