Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, USA; Department of Soil and Environmental Sciences, National Chung-Hsing University, Taichung 402, Taiwan.
Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, USA; Environmental Science and Policy Program, Michigan State University, East Lansing, MI 48824, USA.
Environ Int. 2019 Oct;131:104976. doi: 10.1016/j.envint.2019.104976. Epub 2019 Jul 20.
The dissemination of pharmaceuticals in agroecosystems originating from land application of animal manure/sewage sludge and irrigation with treated wastewater in agricultural production has raised concern about the accumulation of pharmaceuticals in food products. The pathways of pharmaceutical entries via plant roots, transport to upper fractions, and the factors influencing these processes have yet been systematically elucidated, thus impeding the development of effective measures to mitigate pharmaceutical contamination in food crops. In this study, lettuce uptake of thirteen commonly used pharmaceuticals was investigated using a hydroponic experimental setting. Pharmaceutical sorption by lettuce roots was measured in order to evaluate the influence on pharmaceutical transport from roots to shoots. Small-sized pharmaceuticals e.g., caffeine and carbamazepine with molecular weight (MW) <300 g mol and a low affinity to lettuce roots (sorption coefficient Kp < 0.05 L g) manifested substantial transport to shoots. Small-sized molecules lamotrigine and trimethoprim had a relatively strong affinity to lettuce roots (Kp > 12.0 L g) and demonstrated a reduced transport to shoots. Large-sized pharmaceuticals (e.g. MW >400 g mol) including lincomycin, monensin sodium, and tylosin could be excluded from cell membranes, resulting in the predominant accumulation in lettuce roots. Large-sized oxytetracycline existed as zwitterionic species that could slowly enter lettuce roots; however, the relatively strong interaction with lettuce roots limits its transport to shoots. The mass balance analysis revealed that acetaminophen, β-estradiol, carbadox, estrone and triclosan were readily metabolized in lettuce with >90% loss during 144-h exposure period. A scheme was proposed to describe pharmaceutical uptake and transport in plant, which could reasonably elucidate many literature-reported results. Molecular size, reactivity and ionic speciation of pharmaceuticals, as well as plant physiology, collectively determine their uptake, transport and accumulation in plants.
动物粪便/污水污泥土地施用和农业生产中经处理废水灌溉向农业生态系统中散布的药物引起了人们对食品中药物积累的关注。药物通过植物根系进入、向上部转移的途径以及影响这些过程的因素尚未得到系统阐明，从而阻碍了制定有效措施来减轻食品作物中药物污染的发展。在这项研究中，使用水培实验装置研究了生菜对十三种常用药物的吸收。测量了药物被生菜根系的吸附，以评估其对药物从根部向茎叶转移的影响。小分子量的药物，如咖啡因和卡马西平（分子量<300g/mol，与生菜根系亲和力低（吸附系数 Kp<0.05L/g））大量转移到茎叶中。小分子拉莫三嗪和甲氧苄啶与生菜根系具有相对较强的亲和力（Kp>12.0L/g），向茎叶转移的量减少。大分子量的药物（如分子量>400g/mol），包括林可霉素、莫能菌素钠和泰乐菌素，不能通过细胞膜，导致主要在生菜根系中积累。大分子量的土霉素以两性离子形式存在，可以缓慢进入生菜根系；然而，与生菜根系的较强相互作用限制了其向茎叶的转移。质量平衡分析表明，在 144 小时暴露期间，醋氨酚、β-雌二醇、卡巴氧、雌酮和三氯生在生菜中容易代谢，损失率超过 90%。提出了一个描述药物在植物中吸收和转运的方案，该方案可以合理地解释许多文献报道的结果。药物的分子大小、反应性和离子形态，以及植物生理学，共同决定了它们在植物中的吸收、转运和积累。
