Multicompartmental monitoring and associated health risks estimation of some selected pesticides in the aquatic ecosystems of Sungai Besar, Sekinchan, Malaysia.

The use of pesticides for crop production leads to environmental contamination, adversely affecting water and sediment quality, as well as the health of the entire aquatic ecosystem; all of these pose serious public health concerns. Sungai Besar, Sekinchan, a key rice-producing area in Malaysia, has a notable agricultural history. Despite the widespread use of different pesticides, data on organochlorine residues in fish, water, and sediment are lacking. This study aimed to assess the abundance of organochlorine pesticides and/or residues in water, sediment, and fish samples collected from five locations across the paddy fields of Sungai Besar, Sekinchan. The study revealed the detection of five organochlorine pesticides in fish, including lindane, heptachlor, endosulfan, aldrin, and dieldrin. Of the five pesticides, the occurrence of lindane and dieldrin levels (0.018 ± 0.005 to 0.037 ± 0.003 and 0.247 ± 0.01 to 0.380 ± 0.008 µg/g) in snakehead (Channa striatus) and African catfish (Clarias gariepinus) exceeded maximum residue limits (MRLs), implying health risks for the consumers. Water samples were also found to exceed the MRL concentrations for lindane (0.10 ± 0.004 to 0.473 ± 0.01 μg/L), endosulfan (0.13 ± 0.01 to 0.454 ± 0.01 μg/L), aldrin (0.05 ± 0.001 to 0.314 ± 0.01 μg/L), dieldrin (0.06 ± 0.003 to 0.281 ± 0.001 μg/L), heptachlor (0.12 ± 0.005 to 0.36 ± 0.0002 μg/L), endrin (0.05 ± 0.01 to 0.323 ± 0.01 μg/L), methoxychlor (0.04 ± 0.008 to 1.12 ± 0.004 μg/L), and cypermethrin (0.03 ± 0.002 to 0.524 ± 0.005 μg/L), posing significant ecological risks (RQ ≥ 1). Sediment samples were witnessed to contaminate with methoxychlor (0.287 ± 0.01 μg/g) and cypermethrin (0.077 ± 0.001 μg/g). The findings of this study indicate moderate to severe concerns for the aquatic ecosystems and also greater health concerns for the local consumers relying upon fishing from the study area due to potential exposure to long-term risks.