Seasonal variation and risk assessment for the presence of pharmaceuticals in Brazilian urban rivers†

Abstract

The presence of pharmaceuticals in water bodies has become a growing concern due to their potential effects on aquatic life. These compounds enter the environment through various routes, including untreated wastewater, wastewater treatment plants, rainwater runoff, and improper disposal of drugs. Therefore, there has been increasing interest in monitoring the occurrence of pharmaceuticals in natural waters, demanding the development of analytical methods for their detection. In this work, a UHPLC-MS/MS method was developed and validated to quantify acetaminophen, caffeine, diclofenac, and sulfathiazole in a working range varying from 1 to 100 000 ng L⁻¹, in order to assess their occurrence and risk to aquatic life in rivers and creeks located in three southeastern Brazilian metropolitan areas and cities (São José do Rio Preto, Campinas and Belo Horizonte) with different levels of urbanization. Preto, Turvo and Atibaia Rivers and Anhumas, Arrudas, Onça, and Isidoro Creeks were sampled during the dry and wet seasons. The presence of acetaminophen (157–7449 ng L⁻¹), caffeine (60–122 520 ng L⁻¹), diclofenac (62–176 ng L⁻¹), and sulfathiazole (34–40 ng L⁻¹) was confirmed more than once in the samples. The frequency of detection was different for each compound, being higher in the rivers more impacted by urban areas. The risk to aquatic life based on the risk quotient, calculated using the most sensitive PNEC (predicted non-effect concentration) for freshwaters, indicated concern about the concentrations of caffeine and diclofenac in some of the samples analyzed.