三氯生(triclosan,TCS)和三氯卡班(triclocarban,TCC)是2种高效广谱抗菌剂,均具有胚胎毒性、内分泌干扰性和生殖毒性,并可能引发癌症、DNA损伤和不良妊娠结局等,是目前一类广泛关注的新污染物.美国食品与药品监督管理局(US FDA)于2016年已禁止含有TCS和TCC等抑菌剂的非处方抗菌洗浴产品进入市场,而目前在我国其为化妆品准用防腐剂,允许限量使用,且皂类产品不在限制范围内.TCS和TCC作为新兴的外源性化学污染物能够随生活污水的排放进入自然环境,对我国本土水生生物、生态安全和人身健康构成了潜在威胁.为探究TCS和TCC对我国本土鱼种稀有鮈鲫(Gobiocypris rarus)长期暴露及4个不同发育阶段(胚胎期、卵黄囊吸收阶段、仔鱼及幼鱼阶段)的毒性效应,本研究将稀有鮈鲫的受精卵暴露于TCS和TCC中,直至孵化后60 d(60 days post hatch,60 dph),试验过程中监测胚胎期的孵化率,卵黄囊吸收阶段、仔鱼及幼鱼阶段的成活率,长期暴露过程中的生长情况、性分化及内分泌干扰效应等多个指标.研究结果显示,在胚胎期,6.25～100 μg·L-1的TCS和0.938～15 μg·L-1的TCC对稀有鮈鲫的胚胎孵化率没有显著的毒性效应.在仔鱼阶段,6.25～100 μg·L-1的TCS和0.938～15μg·L-1的TCC暴露组30 dph成活率的最高无可观察效应浓度分别为100 μg·L-1和0.938 μg·L-1,根据我国国家标准,TCC对水生环境的危害可判定为长期慢性类别1,而TCS由于试验中的最高浓度未达到1 mg·L-1,无法作出明确的判断,但能判断其对水生环境的危害为非长期慢性类别1.在幼鱼阶段,6.25～100 μg·L-1的TCS和0.938～15 μg·L-1的TCC均对雌性及雄性稀有鮈鲫体内卵黄蛋白原具有一定的诱导作用,但在性分化上没有显著影响.在胚后发育过程中,通过长期暴露,6.25～100 μg·L-1的TCS对稀有鮈鲫体质量有显著毒性效应,随TCS浓度的升高,稀有鮈鲫体质量逐渐降低,TCS对稀有鮈鲫体质量具有抑制作用;0.938～15 μg·L-1的TCC对稀有鮈鲫体质量及体长等生长均无显著影响.此外,研究发现稀有鮈鲫在不同发育阶段的毒性效应存在差异,稀有鮈鲫胚胎期的耐受力明显高于胚后发育阶段,卵黄囊吸收阶段及仔鱼阶段的耐受力低于幼鱼阶段.可见,当更多的生命阶段被包括在一个测试中,能够通过较少的试验动物,获得较多的毒性终点,且测试中不同生命阶段的毒性效应来自同一批试验动物,使不同生命阶段的试验结果更具可比性.
Toxic Effects of Triclosan and Triclocarban on Gobiocypris rarus at Various Developmental Stages during Long-term Exposure
Triclosan(TCS)and triclocarban(TCC)are two highly effective broad-spectrum antimicrobial agents having embryo toxicity,endocrine disruption,and reproductive toxicity.These two chemicals are presently emerging pollutants of wide concerns and may cause cancer,DNA damage,and adverse pregnancy outcomes.In 2016,the US Food and Drug Administration(US FDA)has banned market entry of the over-the-counter antibacte-rial bath products containing antibacterial agents such as TCS and TCC.In China,however,TCS and TCC are still allowed to be used in a limited quantity as quasi-preservatives for cosmetics,and are not restricted for soap products.As emerging exogenous chemical pollutants,TCS and TCC can enter the natural environment with domestic wastewater and pose potential threats to local aquatic lives,ecological security and human health.In or-der to investigate the toxic effects of TCS and TCC on the long-term exposure and four different developmental stages(i.e.,embryo,yolk sac absorption,larval,and juvenile stages)of the Chinese native fish species of Gobiocypris rarus(GR),the fertilized eggs of GR were exposed to TCS and TCC until 60 days post hatching(60 dph)in this study.The results showed that TCS and TCC in the ranges of 6.25～100 μg·L-1 and 0.938～15 μg·L-1,respectively,had no significant toxic effects on the embryo hatchability of GR.In the larval stage,the no observed effect concentration(NOEC)of the 30 dph survival rate in the exposure groups of 6.25～100 μg·L-1 TCS and 0.938～15 μg·L-1 TCC were 100 μg·L-1 and 0.938 μg·L-1,respectively.According to the national standards of China,the hazards of TCC to the aquatic environment were classified as long-term chronic category 1.In contrast,it is impossible to make a clear judgment for TCS because its maximum testing concentration did not reach 1 mg·L-1,but the hazards of TCS to the aquatic environment can be judged as the non-long-term chronic category 1.At the juvenile stage,TCS(6.25～100 μg·L-1)and TCC(0.938～15 μg·L-1)could induce vitellogenin in both females and males of GR,but did not affect sexual differentiation.During the postembryonic development,TCS of 6.25～100 μg·L-1 could significantly affect the fish body weight,which gradually decreased with increasing TCS concentration,indicating that TCS could inhibit the body weight of GR.TCC of 0.938～15 μg·L-1had no significant effect on the fish body weight and body length.In addition,it was found that the toxic effects on the different developmental stages of GR were different.The tolerance of GR at embryonic stage was significantly higher than that at postembryonic development stage,while the tolerance at yolk sac absorption stage and larvae stage was lower than that at the juvenile stage.Therefore,when more of these life stages are included in a test,more toxicity endpoints can be obtained by fewer test animals.Moreover,the toxic effects of different life stages in the tests are all from the same batch of the test animals,making the test results of different life stages more comparable.
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