Morrison Shane A, Belden Jason B
Department of Integrative Biology, Oklahoma State University, Stillwater, Oklahoma, USA.
Environ Toxicol Chem. 2016 Sep;35(9):2320-9. doi: 10.1002/etc.3400. Epub 2016 Jun 21.
Nontarget aquatic organisms residing in wetlands are commonly exposed to current-use pesticides through spray drift and runoff. However, it is frequently challenging to measure exposure because of rapid dissipation of pesticides from water and reduced bioavailability. The authors' hypothesis is that freshwater snails can serve as bioindicators of pesticide exposure based on their capacity to passively accumulate tissue residues. Helisoma trivolvis snails were evaluated as biomonitors of pesticide exposure using a fungicide formulation that contains pyraclostrobin and metconazole and is frequently applied to crops surrounding depressional wetlands. Exposure-response studies indicate that H. trivolvis are tolerant of pyraclostrobin and metconazole at concentrations >10 times those lethal to many aquatic species, with a median lethal concentration based on pyraclostrobin of 441 μg/L (95% confidence interval of 359-555 μg/L). Bioconcentration factors ranged from 137 mL/g to 211 mL/g and from 39 mL/g to 59 mL/g for pyraclostrobin and metconazole, respectively. Elimination studies suggested one-compartmental elimination and snail tissue half-lives (t50 ) of approximately 15 h and 5 h for pyraclostrobin and metconazole, respectively. Modeling derived toxicokinetic parameters in the context of an environmentally relevant pulsed exposure suggests that residues can be measured in snails long after water concentrations fall below detection limits. With high fungicide tolerance, rapid accumulation, and slow elimination, H. trivolvis may be viable for biomonitoring of pyraclostrobin and should be investigated for other pesticides. Environ Toxicol Chem 2016;35:2320-2329. © 2016 SETAC.
栖息在湿地中的非目标水生生物通常会通过喷雾漂移和径流接触到当前使用的农药。然而，由于农药在水中迅速消散以及生物可利用性降低，测量暴露情况常常具有挑战性。作者的假设是，淡水蜗牛因其被动积累组织残留的能力，可以作为农药暴露的生物指示物。使用一种含有吡唑醚菌酯和丙环唑的杀菌剂配方对H. trivolvis蜗牛进行评估，该配方常用于低洼湿地周边的农作物。暴露-反应研究表明，H. trivolvis对吡唑醚菌酯和丙环唑的耐受性高于对许多水生物种致死浓度的10倍以上，基于吡唑醚菌酯的半数致死浓度为441μg/L（95%置信区间为359 - 555μg/L）。吡唑醚菌酯和丙环唑的生物富集系数分别为137mL/g至211mL/g和39mL/g至59mL/g。消除研究表明，吡唑醚菌酯和丙环唑的消除符合一室模型，蜗牛组织半衰期（t50）分别约为15小时和5小时。在环境相关脉冲暴露的背景下建模得出的毒代动力学参数表明，即使水中浓度降至检测限以下很长时间后，仍可在蜗牛体内检测到残留。由于对杀菌剂耐受性高、积累迅速且消除缓慢，H. trivolvis可能适用于吡唑醚菌酯的生物监测，并且应针对其他农药进行研究。《环境毒理学与化学》2016年；35:2320 - 2329。© 2016 SETAC。
