Assessment of heavy metal pollution and human health risk in the soil of selected tea plantations from southern Western Ghats, Tamil Nadu, India

Soil pollution on agricultural land has become a significant concern in major tea-producing regions, including Tamil Nadu, a prominent tea-producing state in India. The excessive use of agrochemicals in tea plantations leads to soil contamination, which in turn pollutes tea plantation soil. Tea soil samples were collected in six different tea plantations in commercially important regions from Valparai (Coimbatore), Coonoor, Kundha, Kothagiri, Kattabettu, and Gudalur (Nilgiris), in Tamil Nadu, India. The samples were taken from depths of 0–25 cm across distances ranging from 0–250 m. These samples were digestion procedure followed AOAC method. To assess human health risks, both carcinogenic and non-carcinogenic effects will be evaluated across three primary exposure pathways: ingestion, inhalation, and dermal contact. The study conducted in six major tea-cultivated soils. Five tea plantations' soil samples are highly contaminated with cadmium and at high risk. Geoaccumulation index shows cadmium strongly contaminated in Valparai, Coonoor, and extremely contaminated in Kundha, Kothagiri, and Ooty tea soil samples. The Total Cancer Risk (TCR) in the study area mainly ingestion route values: Cd (0.0000364–0.0000583), followed by Cr (0.0000293–0.0000468), As (0.0000105–0.0000168), and Ni (0.00000269–0.00000431) All the values were higher than USEPA’s of 1 × 10⁶–1 × 10⁴ (USEPA, 2004) consequently, children’s health will be severely affected compared to adults. The current study shows that due to the excess use of agrochemicals and short tea crop cultivation periods, a large amount of heavy metals accumulates in tea plantation soil. As a result, understanding toxic metals and emphasizing the reduction of agrochemicals and the extension of the tea crop cultivation period is crucial. Because soil health is key for food quality, sustainable agriculture, and increasing economic value.