Uptake of the Pharmaceutical Triclosan in Vegetables Fertilized with a Triclosan-containing Biosolids

Abstract

Biosolids produced by municipal sewage treatment facilities may contain various pharmaceuticals, such as Triclosan, a commonly-used antibacterial and antifungal agent contained in soaps, deodorants, toothpastes, mouthwashes, and cleaning supplies. Milorganite® is a biosolids-based fertilizer that has been produced by the Milwaukee Metropolitan Sewerage District for over 85 years. It is widely distributed and sold for lawns and gardens, including vegetable gardens. It contains detectable amounts of Triclosan. A greenhouse study was conducted to evaluate Triclosan concentrations in vegetables fertilized with Milorganite 5–2–0. Milorganite containing Triclosan at 2 mg·kg–1 was mixed at the rate of 1.6 g·L–1 with quartz sand containing sphagnum peat at 100 mL·L–1. A second Milorganite application was surface applied 6 weeks later at the same rate. Lettuce (Lactuca sativa), sweetcorn (Zea mays), carrots (Daucus carota), and tomatoes (Solanum lycopersicum) were grown to provide the edible parts, which were harvested and analyzed for Triclosan. The sweetcorn had the highest concentration of Triclosan, at 29.7 µg·kg–1, followed by tomatoes (8.2 µg·kg–1), carrots (1.1 µg·kg–1), and lettuce (0.8 µg·kg–1), on a fresh-weight basis. Based on an EPA Triclosan reference dose of 0.26 mg·kg–1 body weight per day, it would be impossible to consume sufficient quantities of any of these vegetables to create adverse health effects.