Occurrence and risk assessment of phthalate esters in the Torghabeh River, Northeastern Iran

Phthalate esters (PAEs), a group of well-known endocrine-disrupting chemicals (EDCs), are extensively used in plastic manufacturing and are recognized for their contribution to environmental pollution and potential adverse health effects. Rivers in urban and recreational areas are increasingly threatened by plastic-derived pollutants, yet there is a lack of data on the occurrence, distribution, and risks of PAEs in such environments in Iran. The Torghabeh River, a popular recreational site near Mashhad, may be particularly vulnerable to phthalate pollution due to tourism, waste discharge, and urban runoff. Therefore, this study aimed to identify and quantify PAEs in the water and sediment of the Torghabeh River and to assess their associated human and ecological risks. Water and sediment samples were collected from various locations along the river. After extraction using solid-phase extraction (SPE) for water samples and ultrasonic extraction for sediment samples, PAEs were identified using gas chromatography-mass spectrometry (GC-MS). The results showed that the mean concentration of Σ6PAEs in water was 11,030.8 ng/L, ranging from non-detectable (ND) to 17,477.07 ng/L. In surface sediments, the mean concentration of Σ7PAEs was 9,714.98 ng/g (range: ND-29,226.06 ng/g), while deeper sediments had a mean concentration of 7858.46 ng/g (range ND-15,084.94 ng/g). Di (2-ethylhexyl) phthalate (DEHP) was the predominant compound detected in both water and sediment samples. PAE concentrations were generally higher in sediments than in water. The hazard quotient (HQ) and hazard index (HI) values for human exposure were below established threshold levels; however, DEHP posed a higher dermal exposure risk for children. Ecological risk assessment revealed that Diisobutyl phthalate (DiBP) had a risk quotient (RQ) greater than 1 for fish in both water and sediment, while DEHP exceeded an RQ of 1 for all aquatic species in water. In conclusion, phthalate esters were present at notable concentrations in both water and sediment of the Torghabeh River, with higher accumulation observed in sediments. Although human health risks were generally low, certain compounds-particularly DEHP and DiBP-posed significant ecological risks and increased dermal exposure concerns for children.