State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China.
State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
Environ Pollut. 2015 Dec;207:138-44. doi: 10.1016/j.envpol.2015.09.012. Epub 2015 Sep 12.
Pyrethroid insecticides and metals commonly co-occurred in sediment and caused toxicity to benthic organisms jointly. To improve accuracy in assessing risk of the sediments contaminated by insecticides and metals, it is of great importance to understand interaction between the contaminants and reasons for the interaction. In the current study, permethrin and cadmium were chosen as representative contaminants to study joint toxicity of pyrethroids and metals to a benthic invertebrate Chironomus dilutus. A median effect/combination index-isobologram was applied to evaluate the interaction between sediment-bound permethrin and cadmium at three dose ratios. Antagonistic interaction was observed in the midges for all treatments. Comparatively, cadmium-dominated group (the ratio of toxicity contribution from permethrin and cadmium was 1:3) showed stronger antagonism than equitoxicity (1:1) and permethrin-dominated groups (3:1). The reasons for the observed antagonism were elucidated from two aspects, including bioavailability and enzymatic activity. The bioavailability of permethrin, expressed as the freely dissolved concentrations in sediment porewater and measured by solid phase microextraction, was not altered by the addition of cadmium, suggesting the change in permethrin bioavailability was not the reason for the antagonism. On the other hand, the activities of metabolic enzymes, glutathione S-transferase and carboxylesterase in the midges which were exposed to mixtures of permethrin and cadmium were significantly higher than those in the midges exposed to permethrin solely. Cadmium considerably enhanced the detoxifying processes of permethrin in the midges, which largely explained the observed antagonistic interaction between permethrin and cadmium.
拟除虫菊酯杀虫剂和金属通常共同存在于沉积物中，并共同对底栖生物产生毒性。为了提高评估受杀虫剂和金属污染沉积物风险的准确性，了解污染物之间的相互作用及其相互作用的原因非常重要。在本研究中，选择氯菊酯和镉作为代表性污染物，研究拟除虫菊酯和金属对底栖无脊椎动物摇蚊（Chironomus dilutus）的联合毒性。中值效应/组合指数-等效应线图被应用于评估三种剂量比下结合态氯菊酯和镉之间的相互作用。对于所有处理组，在摇蚊中均观察到拮抗相互作用。与等毒性（1:1）和氯菊酯主导组（3:1）相比，镉主导组（氯菊酯和镉的毒性贡献比为 1:3）表现出更强的拮抗作用。从生物可利用性和酶活性两个方面阐明了观察到的拮抗作用的原因。氯菊酯的生物可利用性，用固相微萃取法测量的沉积物孔隙水中的自由溶解浓度表示，没有因添加镉而改变，这表明氯菊酯生物可利用性的变化不是拮抗作用的原因。另一方面，暴露于氯菊酯和镉混合物中的摇蚊的代谢酶谷胱甘肽 S-转移酶和羧酸酯酶的活性明显高于单独暴露于氯菊酯的摇蚊。镉大大增强了摇蚊对氯菊酯的解毒过程，这在很大程度上解释了氯菊酯和镉之间观察到的拮抗相互作用。
