Ecotoxicological risk and bioaccumulation of triclosan in multi-habitat marine niches: Evidence from southwest peninsular India.

Publication date: Sep 26, 2025

In the post-COVID-19 period, triclosan (TCS), a biocidal compound widely used in pharmaceuticals and personal care products, has gained attention as an emerging contaminant in aquatic environments. Although its presence is well-documented in freshwater systems, limited information is available on its occurrence and ecotoxicological risks in marine environments. The present study investigated TCS concentrations in seawater, sediments and fish samples collected along the southwest coast of India. Elevated levels were recorded at sites influenced by riverine discharges (estuaries), with mean concentrations of 3. 39 ng L in water, 0. 86 ng g in sediments, and 106. 9 ng g in fish tissues. Temporal analysis indicated that TCS levels in the sediment matrix exhibited minimal seasonal variation, with the highest concentration recorded in pre-monsoon period. Rivers served as major pathways for TCS transport to the marine environment, contributing an estimated annual flux of 26. 2 kg through water and 0. 75 metric tons through sediments, with the Tamirabarani River alone accounting for approximately 8. 14 kg yr. After its release, TCS persistence in the marine system was positively influenced by total organic carbon (TOC), biological oxygen demand (BOD), and chemical oxygen demand (COD) and negatively by pH, salinity and electrical conductivity (EC). Ecotoxicological risk assessment indicated significant risks to primary producers (Risk Quotient, RQ > 1), with TCS in sediment matrix contributing substantially to the overall risk. Bioaccumulation patterns in fish were more pronounced in estuarine regions and varied among species according to their niche and feeding habits.

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