Enhancement of carcinogenic and non-carcinogenic health risk of heavy metals in eggs and ecological impacts: A comparative study before and after gold mine reoperation in Thailand

Motivated by previously documented toxicological hazards in proximity Northern Thailand’s gold mining operations, this investigation undertakes a comparative assessment of heavy metal residues in avian eggs across pre- and post-reoperation phases. Such analyses are essential for establishing regulatory baselines and for mitigating pervasive risks posed by mining-derived contaminants to local food safety and public health. This study evaluated total mercury (THg), Pb, Cd, and Mn contamination in poultry eggs from farms near a gold mining area in association with its contamination in the ecological habitat after mining activity resumed in northern Thailand in 2024. Mining activities represented the dominant anthropogenic source of heavy metal in avian eggs, with Pb, Cd, and Mn exhibiting preferential sequestration by maternal transfer processes. Subsequent to mining cessation, hazard index (HI) values increased substantially by 20- to 70-fold primarily attributable to THg. Free-grazing ducks manifested the most pronounced escalation, with HI values exceeding 70-fold relative to pre-mining baselines. Critically, all incremental lifetime cancer risk (ILCR) estimates surpassed the 10 −6 benchmark, while post-mining Pb and Cd exposures in chicken eggs exceeded the 10 −4 threshold for unacceptable carcinogenic risk across all age cohorts. Although Cd-associated risk declined, Pb-related carcinogenic risk intensified six-fold, signifying a severe toxicological hazard. These findings underscore the urgent necessity for continuous biomonitoring and coordinated stakeholder interventions to mitigate public health and food security risks in mining-impacted ecosystems.