Abundance of low-molecular-weight phthalates among contaminants of emerging concerns in a riverine system

The Periyar River, a vital water resource for Kochi, faces significant pollution issues. This study examines the distribution of three low molecular weight phthalic acid esters (PAEs) - dimethyl phthalate (DMP), diethyl phthalate (DEP), and dibutyl phthalate (DBP) - in areas affected by industrial and municipal effluents, using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Additionally, the seasonal variations of PAEs during pre-monsoon (dry) and post-monsoon (wet) periods were assessed. The highest level of PAEs was found in the pre-monsoon season with DEP as the major constituent, with a concentration range of 910.81 ng/L 1974.80 ng/L, followed by DBP (362.84 ng/L - 1836.60 ng/L) and DMP (140.04 ng/L - 328.81 ng/L). Ecological risk assessment of the aquatic communities like algae, crustaceans, and fish showed low to moderate risk, whereas human health risk assessment of DEP and DBP in the study site indicated a high risk with risk quotient (RQ) > 2 and RQ > 1, respectively, during the pre-monsoon season. A few contaminants of emerging concern (CECs) (Atenolol, Benzophenone, Caffeine, Cetirizine, Diphenylamine, Diuron, Lidocaine, Mefenamic acid, Metoprolol, N,N-diethyl-meta-toluamide (DEET), Oxybenzone, Propranolol, Timolol, and Triamterene) were also targeted seasonally from the study area. The toxicological profile of PAEs and other CECs was evaluated using the Environmental Protection Agency's (EPA's) ToxCast database. The widespread occurrence of these chemicals in surface water is concerning, so frequent monitoring and regulations are necessary.