Health risks of arsenic buildup in soil and food crops after wastewater irrigation

Highlights: • Rare literature data regarding As-contamination and associated health risks from municipal wastewater irrigations • This study collected 17 wastewater, 108 soil & 65 plant samples from 15 sites of Vehari. • Arsenic levels vary in wastewater (5–64 μg/L), soil (2–20 mg/kg) & plant (0–6 mg/kg). • Cancer risk factor showed possible As risks (>10⁻⁴) for certain food crops, especially wheat. • Use of multiple and diversified food crops is recommended to minimize possible As risk. Despite considerable research of arsenic (As) level in ground/drinking water of Pakistan, scarce data is available regarding irrigation water contamination by As and associated health risks. The municipal wastewater is routinely applied for soil irrigation in peri-urban agriculture of the country. Since the wastewater composition/contamination and its allied consequences greatly vary in different areas, therefore, it is imperative to check the possible health risks in areas where untreated wastewater is being applied for food crop production. This study analyzed potential health hazards of As-buildup in soil and food plants irrigated with municipal wastewater growing under natural conditions. Sixteen wastewater irrigation locations were selected in District Vehari. From these sites, a total of 16 wastewater samples, 108 soil samples and 65 plant samples were collected for As analysis. Total As contents in wastewater (5.3–63.6 μg/L), soil (1.4–19.6 mg/kg) and plants (0–6.5 mg/kg) greatly varied with sampling location, soil depths and plant type. Based on total As contents in edible tissues, risk assessment parameters, especially cancer risk factor, showed possible health risks (> 0.0001) for wheat crops for children while no risks for other food crops. The use of multiple and diversified food crops is recommended in the study area to minimize the possible risk of As exposure and poisoning. The study also anticipates some future viewpoints considering the on-ground situation of wastewater use, possible exposure of metal(loid)s to human and associated health concerns at local and global scale.