Uptake of antibiotics and their toxicity to lettuce following routine irrigation with contaminated water in different soil types

To address the issue of global freshwater shortages, wastewater has become an increasingly valuable alternative for crop irrigation. As a result, trace levels of emerging contaminants, including antibiotics, may occur in water used for food production. The objective of this study was to investigate how soil texture affected the availability and uptake of three chemically diverse antibiotics (lincomycin, oxytetracycline, and sulfamethoxazole) by lettuce grown in soils comprised of silt clay and increasing percentages of sand. Lettuce was irrigated routinely with antibiotic-amended water (1 mg/L) from seed germination through the first harvest (40 days), switched to control water, and fate monitored at days 45 and 50. Sulfamethoxazole was the only compound where tissue concentrations increased with increasing sand concentrations to 24.7 ng/g fresh weight (FW). Lincomycin was most readily accumulated with increasing concentrations observed at the second harvest in both the loam (68.3 ng/g FW) and sandy soils (66.6 ng/g FW). Apparent toxicity of the antibiotic mixture resulted in decreasing plant mass (37-72%) with increasing sand content. Results from this study show that soil texture impacts plant growth, contaminant transport, plant uptake, and toxic effects, which all contribute to, observed concentrations in edible plant portions.