Uptake of human pharmaceuticals and personal care products by cabbage (Brassica campestris) from fortified and biosolids-amended soils

Abstract

Human pharmaceuticals and personal care products (PPCPs) are routinely found in biosolids from wastewater treatment plants (WWTPs). Once land applied, the PPCPs in biosolids are potentially available for plant uptake and bioaccumulation. This study used a greenhouse model to investigate uptake of PPCPs commonly detected in biosolids by the agricultural plant Chinese cabbage (Brassica campestris). Two series of greenhouse experiments were conducted as part of this project. In the first set of experiments, four pharmaceuticals were added to an organic matter-rich soil in environmentally relevant concentrations based on typical biosolids application rates, resulting in final soil concentrations of 2.6 ng g⁻¹ carbamazepine, 3.1 ng g⁻¹ sulfamethoxazole, 5.4 ng g⁻¹ salbutamol, and 0.5 ng g⁻¹ trimethoprim. In the second set of experiments, the cabbage was grown in soil amended with an agronomic rate of biosolids from a local WWTP. The ambient concentration of PPCPs in the biosolids resulted in final soil concentrations of 93.1 ng g⁻¹ carbamazepine, 67.4 ng g⁻¹ sulfamethoxazole, 30.3 ng g⁻¹ salbutamol, 433.7 ng g⁻¹ triclosan, and 24.7 ng g⁻¹ trimethoprim. After growing to maturity, the aerials of the plants were separated from roots and the two tissue types were analyzed separately. All four human pharmaceuticals were detected in both tissues in the cabbage grown in the soil fortified with the four pharmaceuticals with median concentrations of 255.4 ng g⁻¹ aerials and 272.9 ng g⁻¹ roots carbamazepine; 222.8 ng g⁻¹ aerials and 260.3 ng g⁻¹ roots sulfamethoxazole; 108.3 ng g⁻¹ aerials and 140.6 ng g⁻¹ roots salbutamol; and 20.6 ng g⁻¹ aerials and 53.7 ng g⁻¹ roots trimethoprim. Although all study compounds were present in the biosolids-amended planting soil, only carbamazepine (317.6 ng g⁻¹ aerials and 416.2 ng g⁻¹ roots), salbutamol (21.2 ng g⁻¹ aerials and 187.6 ng g⁻¹ roots), and triclosan (22.9 ng g⁻¹ aerials and 1220.1 ng g⁻¹ roots) were detected in the aerials of the cabbage. In addition to the study compounds detected in the aerials, sulfamethoxazole was detected in the roots of one of the plants in the biosolid-amended soil. In comparison to many previous studies that have utilized PPCP concentration that exceed environmentally relevant concentrations, plants in this study were exposed to environmentally relevant concentrations of the PPCPs, yet resulted in uptake concentrations similar to or greater than those reported in comparable studies. We suggest that rhizosphere conditions, particularly the presence of dissolved organic matter in the planting matrix, might be one of the critical factors determining mobilization and bioavailability of xenobiotic compounds such as PPCPs.