Phyto -accumulation of Antimicrobials Triclocarban and Triclosan by Food Crops

1. Phyto-accumulation of Antimicrobials Triclocarban and Triclosan by Food Crops Shiny Mathews, Shannon Henderson, NirojAryaland Dawn Reinhold Department of Biosystems and Agricultural Engineering, Michigan State University, East Lansing, MI-48824 Triclocarban Results and Discussion Abstract • Triclocarban (TCC) and triclosan (TCS) are antimicrobials in various personal care products that find their way to agricultural lands by the application of bio-solids or waste-water. • Antimicrobial uptake and translocation was studied in cucumber, tomato, pumpkin and zucchini plants in hydroponic systems when treated with 287-500 ug/g of TCC and TCS for 4 or 8 weeks. • The concentration of antimicrobials in the nutrient media was monitored weekly. The crop shoot and root were analyzed for TCC and TCS. • There was a decrease in antimicrobial concentrations with time in the control and test media in which crop plants were grown. • Triclocarbanconcentration in the roots and shoots of the plants ranged from 133.0-531.4 µg/g and 0.02-0.06 µg/g respectively. Triclosan concentrations, on the other hand, ranged from 12.1-815.7 µg/g and 0.4-1.2 µg/g respectively. • Further studies on different crops will help understand the risks associated with phytoaccumulation of antimicrobials and investigate preventive measures. • A reduction with time in TCC and TCS concentration in control media as well as with plant indicates chemical or photochemical loss (Figure 1). • The concentrations of TCC in plant roots ranged from 133.0-531.4 µg/g and that of TCS ranged from 12.1-815.7 µg/g (Figure 2a). • The concentration of TCC in the plant shoots ranged from 0.02-0.06 µg/g and that of TCS ranged from and 0.4-1.2 µg/g (Figure 2b) . • Similar results were observed in pumpkin and zucchini with a higher TCC and TCS concentration in the root than shoot (Figure 3). • The translocation factors (TF) in all the crops tested was < 0.2; the highest being in TCC and TCS uptake by Zucchini. • The low translocation factor in TCC may be attributed to its low solubility and higher log Kow than TCS. Triclosan a) b) Introduction • Triclocarban and triclosan can result in endocrine disruption and antibiotic resistance (Christen et al., 2010; Suller and Russell, 2000). • These antimicrobials bioaccumulate in plant tissue and affect various stages of plant growth including germination (Stevens et al., 2010), shoot elongation in wheat (An et al., 2009) and root elongation in rice and cucumber (Liu et al., 2009). • Soil column studies indicate that pumpkin, zucchini and switch grass accumulated TCC and TCS in roots at concentrations ranging from 15-35 ug/g (Aryal and Reinhold, 2011). • Both TCC and TCS bio-accumulated in the roots and seeds of soybean when raised using simulated biosolids and waste water (Wu et al., 2010). • The bioaccumulation of pharmaceuticals in cabbage was higher in the roots than the leaves and the stem. (Herklotz et al., 2010). Conclusion Figure 1.Concentration of a) TCC and b) TCS in the control, tomato and cucumber media treated with 500ppb TCC & TCS for 4 weeks • The study indicates higher accumulation of TCC and TCS in plant roots than in shoot tissue of pumpkin, zucchini, cucumber and tomato. • Root crops and leafy vegetables are of significant concern due to their direct and raw consumption. • Uptake and translocation of TCC and TCS is crop dependent and hence it is important to assess bioaccumulation in more crops. • Further risk assessment studies are to be done to understand the effect of TCC/TCS on human health. a) b) Acknowledgements • Dr. Yunjie Ding - assistance in solvent extraction. • USDA-AFRI Grant # RC 100165. Objective- To assess the accumulation of antimicrobials, TCC and TCS, in crop plants raised in a hydroponic system. References Figure 2.Concentration of TCC and TCS in cucumber and tomato a) root and b) shoot treated with 500ppb TCC & TCS for 4 weeks • An, J., Q. Zhou, Y. Sun and Z. Xu. 2009. Chemosphere. 76:1428-1434. • Aryal, N. and D.M. Reinhold. 2011. Water Research. 45:5545-5552. • Christen, V., P. Crettaz, A. Oberli-Schrämmli, and K. Fent. 2010. Chemosphere. 81:1245-1252. • Herklotz, P.A., P. Gurung, B. VandenHeuvel, and C.A. Kinney. 2010. Chemosphere. 78:1416-1421. • Liu, F., G.-G. Ying, L.-H. Yang, and Q.-X. Zhou. 2009. Ecotoxicology and Environmental Safety. 72:86-92. • Stevens, K.J., S.-Y. Kim, S. Adhikari, V. Vadapalli, and B.J. Venables. 2009. Environmental Toxicology and Chemistry. 28:2598-2609. • Suller, M.T.E., and A.D. Russell. 2000. Journal of Antimicrobial Chemotherapy 46:11-18. Materials and Methods • Cucumber, tomato, pumpkin and zucchini of uniform age, size and with established roots were transferred to nutrient solution. • After 1 week of acclimatization, plants were transferred to 1 L amber glass jars with 900 mL nutrient test solutions having 500 ug/g TCC and TCS. No-plant controls in the TCC/TCS media and plant control in the absence of TCC/TCS in the nutrient media were also maintained. • Media samples were collected weekly and analyzed for TCC/TCS. • After 4 weeks, the plant roots were washed in DI water, separated into root and shoot, weighed and dried. • Dried plant samples were extracted for TCC and TCS in an accelerated solvent extractor with 1:1 methanol: acetone . The extract was dried using N gas and residue dissolved in 1:1 methanol: acetone. • The extracted TCC and TCS were analyzed using LC/MS (ESI-)d Contact Info: Dr. Shiny Mathews, Research Associate, 216 Farrall Hall, Michigan State University, East Lansing, MI-48824 Email: shinymj@msu.edu Figure 3.Mass fraction of TCC & TCS in pumpkin, zucchini and control treated with 315ppb of TCC and 287 ppb of TCS for 8 weeks