Toxicologia Ambiental e Analítica

Occurrence of Selected Pesticides and PCPs in Surface Water Receiving Untreated Discharge in Pakistan

Abstract

Maryam Saad1, Dilawar Farhan Shams, Waliullah Khan, Aamir Ijaz, Muhammad Qasim1, Ayesha Hafeez, Aisha Khan, Shams Ali Baig and Nisar Ahmed

This study investigated the presence of four pesticides (carbaryl, methomyl, carbofuran and chlorpyrifos) and two personal care products (PCPs) i.e., triclosan (TCS) and caffeine in River Kabul, upper River Indus and Kalpani stream receiving untreated wastewater from major towns in northern Pakistan. PCPs were also examined in domestic wastewater in Mardan district, Pakistan with untreated sewage disposal as common elsewhere in the country. Analysis were performed using liquid chromatography with a triple quadrupole tandem mass spectrometry (LC-MS/MS). All the target pesticides were detected in surface water bodies and in domestic sewage in various concentrations. Methomyl in River Kabul at maximum concentration of 8.3 μg/L was found above its reported LC50 for water fleas. PCPs level in sewage were comparable to other countries but in the absence of any treatment practice, environmental discharge to water bodies was higher by many orders of magnitude compared to treated effluent. Eco-toxicological risk assessment revealed a risk quotient (RQ) of >1 for methomyl, chlorpyrifos and carbofuran for water fleas and fish in River Kabul, River Indus and Kalpani stream and TCS for algae in Kalpani indicating a serious toxicity risk to aquatic organisms in these rivers.