Institute of Aquatic Ecology, University of Girona, Spain.
Aquat Toxicol. 2010 Feb 18;96(3):225-33. doi: 10.1016/j.aquatox.2009.10.024. Epub 2009 Nov 10.
Among increasingly used pharmaceutical products, beta-blockers have been commonly reported at low concentrations in rivers and littoral waters of Europe and North America. Little is known about the toxicity of these chemicals in freshwater ecosystems while their presence may lead to chronic pollution. Hence, in this study the acute toxicity of 3 beta-blockers: metoprolol, propranolol and atenolol on fluvial biofilms was assessed by using several biomarkers. Some were indicative of potential alterations in biofilm algae (photosynthetic efficiency), and others in biofilm bacteria (peptidase activity, bacterial mortality). Propranolol was the most toxic beta-blocker, mostly affecting the algal photosynthetic process. The exposure to 531microg/L of propranolol caused 85% of inhibition of photosynthesis after 24h. Metoprolol was particularly toxic for bacteria. Though estimated No-Effect Concentrations (NEC) were similar to environmental concentrations, higher concentrations of the toxic (503microg/L metoprolol) caused an increase of 50% in bacterial mortality. Atenolol was the least toxic of the three tested beta-blockers. Effects superior to 50% were only observed at very high concentration (707mg/L). Higher toxicity of metoprolol and propranolol might be due to better absorption within biofilms of these two chemicals. Since beta-blockers are mainly found in mixtures in rivers, their differential toxicity could have potential relevant consequences on the interactions between algae and bacteria within river biofilms.
在越来越多使用的药物产品中，β-受体阻滞剂在欧洲和北美的河流和近岸水域中常以低浓度被检出。关于这些化学物质在淡水生态系统中的毒性知之甚少，而它们的存在可能导致慢性污染。因此，在这项研究中，使用几种生物标志物评估了 3 种β-受体阻滞剂（美托洛尔、普萘洛尔和阿替洛尔）对河流生物膜的急性毒性。一些标志物可指示生物膜藻类（光合作用效率）的潜在变化，而其他标志物则可指示生物膜细菌（肽酶活性、细菌死亡率）的潜在变化。普萘洛尔是最具毒性的β-受体阻滞剂，主要影响藻类的光合作用过程。暴露于 531μg/L 的普萘洛尔在 24 小时后导致光合作用抑制了 85%。美托洛尔对细菌特别有毒。尽管估计的无效应浓度（NEC）与环境浓度相似，但毒性更高的浓度（503μg/L 的美托洛尔）会导致细菌死亡率增加 50%。阿替洛尔是这三种测试的β-受体阻滞剂中毒性最小的。只有在非常高的浓度（707mg/L）下，才会观察到毒性超过 50%的情况。美托洛尔和普萘洛尔的毒性较高可能是由于这两种化学物质在生物膜内更好地吸收所致。由于β-受体阻滞剂主要在河流中以混合物的形式存在，它们的差异毒性可能对河流生物膜中藻类和细菌之间的相互作用产生潜在的相关影响。
