铅染毒致斑马鱼焦虑样神经行为及其机制研究

目的:本研究旨在探索铅染毒是否会导致斑马鱼焦虑的发生,并对其机制进行初步探索。方法:于2020年5月,收集受精后4 h（4hpf）的斑马鱼胚胎,以E3培养液作为对照组,不同的铅染毒浓度（6、12、24、48 μmol/L）作为染毒组,染毒时间为140 h。计算144 hpf斑马鱼的胚胎死亡率、胚胎孵化率和幼鱼畸形率;观...     

PFOS对斑马鱼胚胎发育及SOD、MDA和GSH含量的影响

目的观察全氟辛烷磺酸盐(perfluorooctane sulphonate,PFOS)对斑马鱼胚胎发育的影响及其可能的毒作用机制。方法成年健康斑马鱼雌雄按1:1的比例交配产卵,分别用不同浓度的PFOS(0.1,0.5,1.0,2.0和5.0 mg/L),对受精后4 h(four-hour post-fertilization,4hpf)斑马鱼胚胎进行染毒,统计斑马鱼胚胎受精后48 h的心跳、72 h的孵出率、24h、48 h、72 h、96 h、120 h的死亡率和畸形率,检测120 hpf斑马鱼幼鱼的MDA、SOD和GSH的含量。结果与对照组相比较,随着PFOS染毒浓度的增加,斑马鱼胚胎的孵化率降低、心跳减缓、畸形率和死亡率增加,120 hpf幼鱼组织SOD和GSH含量下降,MDA含量增加。当PFOS达到5.0 mg/L时,斑马鱼的48 hpf的心率由对照组的(180.5±4.6)次/min下降到(109.3±5.2)次/min、72 hpf的孵出率由对照组的98.31%下降到21.53%,并且120 hpf的死亡率为60.8%、120 hpf的畸形率为59.17%。120 hpf幼鱼组织SOD和GSH的含量分别由对照组的(12.5±2.13)U/g protein、(7.32±0.79)nmol/mg protein下降到(8.21±2.18)U/g protein和(4.53±0.85)nmol/mg protein,而MDA的含量由对照组的(0.61±0.12)nmol/mg protein上升到(1.82±0.16)nmol/mg protein。结论 PFOS导致斑马鱼胚胎体内的氧化应激可能是其发育毒性的机制之一。     

农利灵对斑马鱼胚胎发育的毒性

[目的]探讨农用杀菌剂农利灵（vinclozolin）对斑马鱼（Brachydanio rerio）的胚胎发育毒性及其机制。[方法]采用水浴染毒法，将受精后2h（hours post fertilization，hpf）内的斑马鱼卵分别暴露于浓度为12．5、25、50、100μg／mL的农利灵，作为4个染毒组，同时设置溶剂（DMSO）对照组、10μg／mL睾酮（testosterone）组及10μg／mL睾酮＋50μg／mL农利灵混合组。通过死亡率、孵化时间、发育畸形等指标评价农利灵的胚胎发育毒性。[结果]农利灵染毒组的胚胎死亡率分别为52．6％、68．4％、85．0％、100．0％，明显高于溶剂对照组（10．0％），P〈0．01，并呈剂量-效应关系。比较孵化时间，12．5μg／mL农利灵染毒组高于溶剂对照组（t=4．077，P〈0．05）。 10μg／mL睾酮＋50μg／mL农利灵混合组的死亡率为51．2％，低于50μg/mL农利灵染毒组的死亡率85．0％（X^2=6．53，P〈0．05）。此外，在农利灵染毒组观察到脊柱弯曲、心包囊肿等发育畸形，其畸形与睾酮染毒组所观察到的畸形相似。[结论]农利灵可延迟斑马鱼的胚胎发育、具有胚胎致死毒性和致畸毒性，其毒性至少有部分是来源于抗雄性激素样作用。     

CdSe/ZnS量子点对斑马鱼胚胎发育的影响

目的研究Cd Se/Zn S量子点对斑马鱼胚胎发育的影响。方法以0、0.5、1、2、4、8和16 nmol/L Cd Se/Zn S量子点分别处理斑马鱼胚胎,于受精后24、48、72、96和120 h(简称hpf)5个时间点分别观察各自具有代表性的毒理学终点。结果在120 hpf时,Cd Se/Zn S量子点对斑马鱼胚胎的LC50为21.38 nmol/L(95%CI:17.21~26.57)。量子点Cd Se/Zn S对斑马鱼胚胎24 hpf时60 s内胚胎自主运动频率,48 hpf 60 s内心率、胚胎孵化率、死亡率等均有明显影响,高浓度8 nmol/L和16 nmol/L组Cd Se/Zn S量子点在120 hpf时可致斑马鱼胚胎发生心包水肿、肝脏变小、卵黄囊吸收延迟、肠道发育异常及肌肉变性等中毒症状。结论 8 nmol/L及以上浓度Cd Se/Zn S量子点对斑马鱼胚胎具有较强的发育毒性,暴露浓度和时间的增加,Cd Se/Zn S量子点可造斑马鱼胚胎死亡率升高。     

氯化三丁基锡对斑马鱼胚胎发育的影响

目的观察氯化三丁基锡(Tributyltin chloride,TBTCl)对斑马鱼胚胎发育和幼鱼死亡的影响。方法成年健康斑马鱼雌雄按1∶1的比例交配产卵,分别用不同质量浓度的TBTCl对受精后4 h(Four-hour post-fertilization,4 hpf)斑马鱼进行染毒实验,统计斑马鱼胚胎受精后48 h的心率,72 h的孵出率,24、48、72、96、120 h的死亡率和畸形率。结果与对照组相比较,随着TBTCl染毒质量浓度的增加,斑马鱼胚胎的孵化率降低、心跳减缓、畸形率和死亡率增加。当TBTCl达到80μg/L时,斑马鱼的48 hpf的心率由对照组的(182.5±3.6)次/min下降到(130.3±3.2)次/min,72 hpf的孵出率由对照组的97.46%下降到23.08%,并且120 hpf的死亡率为65.00%、畸形率为69.17%。结论TBTCl能影响斑马鱼胚胎发育,导致斑马鱼胚胎和幼鱼的畸形与死亡。     

丁草胺对斑马鱼及其胚胎发育毒性影Ⅱ向的研究

目的探讨丁草胺对斑马鱼及其胚胎的发育毒性,并确定其最大未观察到有害作用浓度。方法参照OECD推荐的方法,选用急性毒性试验、肝脏酶活性测定及胚胎发育毒性试验进行研究。斑马鱼及其胚胎通过水环境暴露接触丁草胺后,分别测定LC50、超氧化物歧化酶（SOD）活性、腺苷三磷酸酶（ATPase）活性、孵化率、死亡率、畸变率等指标。结果 丁草胺对斑马鱼的96h LC50为0．951mg／L（95％可信限：0．681～1．313mg／L）,属极高毒类除草剂。在0．16～0．32mg／L浓度范围内,丁草胺对SOD酶活性有抑制作用;在0．08～0．32mg／L浓度范围内,丁革胺对Aq、Pase酶活性有抑制作用。丁草胺对斑马鱼胚胎的发育也有明显的影响。对照组与丁草胺各处理组的120h孵化率分别为96％、92％、72％和44％,120h死亡率分别为2％、4％、10％和20％,120h畸变率分别为2％、2％、10％和16％。丁草胺处理组的孵化牢低于对照组,死亡率、畸变牢高于对照组。与对照组相比,0．018和0．036mg／L丁草胺处理组胚胎发育明显迟缓,仔鱼身长明显变短,差异有统计学意义。结论丁草胺是一种高毒除草剂,对斑马鱼肝脏ATPase和SOD酶活性有抑制作用,能致斑马鱼胚胎发育迟缓和畸变。在本试验条件下,丁草胺最大未观察到有害作用浓度为0．009mg／L。     

氯代苯类化合物对斑马鱼胚胎的单一急性毒性

[目的]为进一步开展水生生物毒理实验研究剂量和毒理学终点选择提供科学依据,并初步揭示氯代苯类化合物致毒机制。[方法]以氯代苯类化合物为测试毒物（包括一氯苯、邻二氯苯、间二氯苯、对二氯苯和1,2,4-三氯苯）,以斑马鱼胚胎为测试对象,进行单一急性毒性测试。实验选用24孔细胞培养板作为胚胎染毒实验容器。从胚胎染毒开始间隔4h显微观察,记录氯代苯类化合物对斑马鱼胚胎单一急性毒性效应（包括致死效应和亚致死效应）,描述相应毒理学终点的变化情况,直至72h结束。[结果]通过实验测出氯代苯类化合物各毒理学终点的EGo值,例如4h胚胎发育终止EC50值（mg／L）：1,2,4．三氯苯为24．72,对二氯苯为76．47,间二氯苯为77.35,邻二氯苯为86.31,一氯苯为89．43等;大量数据显示其毒性大小依次为：1,2,4．三氯苯〉对二氯苯〉间二氯苯〉邻二氯苯〉一氯苯。[结论]氯代苯类化合物对斑马鱼胚胎毒性大小与化合物相对分子质量大小、取代基数量多少以及取代位置有关,相对分子质量越大、取代基数量越多其毒性越大。     

Aroclor1254对斑马鱼胚胎发育、肝脏组织结构及其卵黄蛋白原基因的影响

[目的]使用脊椎动物模型斑马鱼评价Aroclor1254对斑马鱼胚胎发育、肝脏组织结构以及卵黄蛋白原（vtg）基因表达的影响,为Aroclor1254的毒性效应研究提供基础数据,以期选择Aroclor1254污染的敏感指标,进行早期污染监测和预警。[方法]将斑马鱼及其胚胎暴露在不同浓度的Aroclor1254溶液中,运用斑马鱼胚胎发育技术和组织病理观察法以及实时定量反转录聚合酶链反应（RT-PCR）检测Aroclor1254对斑马鱼胚胎发育的影响、形态学的改变和卵黄蛋白原（vtg）基因的表达。[结果]斑马鱼胚胎试验显示,3．3、6．5、10．0mg／L Aroclor1254等均可诱导肝变性、肝脏发育不全,其中3.3mg／L Aroclor1254诱导斑马鱼卵黄部分变性,6．5、10．0mg／L Aroclor1254诱导斑马鱼卵黄大部分或者全部变性。肝脏组织病理观察发现,2．0、10．0、50．0μg/L Aroclor1254肝细胞肿大,胞质疏松,空泡明显增加,细胞质中可见脂沉积。vtgmRNA的表达在Aroelor1254暴露的斑马鱼个体中产生了显著的改变,雌鱼中表达普遍呈抑制趋势,其中以2．0μg／L抑制现象最明显,而在雄鱼中该剂量组vtg表达量被显著诱导。[结论]研究表明Aroclor1254对斑马鱼及其胚胎具有毒性效应,肝脏是产生毒性效应的重要靶器官。     

微囊藻毒素-LR和二甲苯对斑马鱼胚胎的毒性作用

目的 研究二甲苯和微囊藻毒素-LR(MC-LR)对斑马鱼胚胎的毒性作用.方法 将斑马鱼胚胎分为对照(培养液)组和MC-LR单独染毒(25～1 000 μg/L)组及二甲苯单独染毒(2.5～40 mg/L)组以及MC-LR(25～400 μg/L)+二甲苯(2.5～40 mg/L)联合染毒组,每组36个.测定斑马鱼胚胎的死亡情况、孵化情况以及畸形情况,并测定斑马鱼幼鱼平均速度.结果 当MC-LR和二甲苯的浓度分别达到100 μg/L和5 mg/L时,会对胚胎造成致死作用.随着二甲苯和(或)MC-LR染毒浓度的升高,斑马鱼胚胎的孵化率呈下降趋势,死亡率和畸形率均呈升高趋势,而幼鱼的运动速度减慢.结论 二甲苯和MC-LR对斑马鱼胚胎具有致死、致畸作用,并影响斑马鱼的发育.     

应用中脑细胞微团培养技术探讨双酚A的发育毒性

目的 为揭示双酚A(BPA)是否具有神经系统发育毒性及其毒作用机制提供实验依据。方法 采用微团培养技术观察不同浓度的BPA(0—60mg／L)对体外培养的13d龄Wistar大鼠胚胎中脑细胞分化的影响及其细胞毒性作用。结果 BPA对体外培养的大鼠胚胎中脑细胞的存活和分化均有抑制作用并呈现出明显的剂量反应关系。BPA对中脑细胞的50％细胞存活抑制浓度(ICV50)和50％分化抑制浓度(ICD50)分别为57．2mg/L和24．6mg／L。两者比值为2.33。结论 BPA对大岚胚胎中脑细胞分化的抑制作用大于对细胞存活的抑制作用。按照Flint等人推荐的体外致畸分类标准，BPA属于阳性致畸物。     

Toxic effects of 1-methyl-3-octylimidazolium bromide on the early embryonic development of the frog Rana nigromaculata

Toxic effects of 1-methyl-3-octylimidazolium bromide ([C8mim]Br) on the early embryonic development of the frog Rana nigromaculata were evaluated. Frog embryos in different developmental stages (early cleavage, early gastrula, or neural plate) were exposed to 0, 45, 63, or 88.2 mg/L of the ionic liquid [C8mim]Br for 96 h. The 96-h median lethal concentration values at the early cleavage, early gastrula, and neural plate stages of development were 85.1, 43.4, and 42.4 mg/L, respectively. In embryos exposed to [C8mim]Br, the duration of embryo dechorionation was prolonged in the early cleavage and neural plate, but not the early gastrula, stages of development compared with control embryos. Embryos in the neural plate developmental stage were found to have the highest mortality rate following [C8mim]Br exposure. These results suggest that [C8mim]Br has toxic effects on the early embryonic development of the frog.     

Chronic effects of silver exposure on ion levels, survival, and silver distribution within developing rainbow trout (Oncorhynchus mykiss) embryos

Rainbow trout embryos were chronically exposed to silver (as AgNO3) in moderately hard water (120 mg CaCO3/L, 0.70 mM Cl-, 1.3 mg/L dissolved organic matter. 12.3+/-0.1 degrees C) at nominal concentrations of 0.1, 1, and 10 microg/L (measured = 0.117+/-0.008, 1.22+/-0.16, and 13.51+/-1.58 microg/L, respectively) to investigate the effects on mortality, ionoregulation, and silver uptake and distribution of the embryo. Mortalities in the low concentrations (0.1 and 1.2 microg/L) were not significantly different from controls throughout embryonic development (days 1-32 postfertilization). Mortalities of embryos in the 13.5-microg/L treatment reached 56% by day 32 postfertilization (33% when accounting for control mortality), by which time more than 50% of surviving embryos had hatched. Accumulation of silver in whole embryos of 1.2- and 13.5-microg/L treatments reached the highest concentrations of 0.13 and 0.24 microg/g total silver, respectively, by day 32, but whole embryo silver burden was not correlated with mortality. Silver concentrations in different compartments of the whole embryo (chorion, dissected embryo, and yolk) were greatest just before hatch and were higher in the chorion for all experimental treatments. Up to 85% of total whole embryo silver content was bound to the chorion, which acts as a protective barrier during silver exposure. Whole embryo Na+ concentration in the 13.5-microg/L treatment was significantly reduced relative to controls from days 23 to 32 postfertilization, and levels in the embryo were reduced by 40% at day 32 postfertilization, indicating that silver toxicity in the whole embryo is associated with an ion regulatory disturbance that is similar to the acute effect of AgNO3 in juvenile and adult trout.     

The pesticide malathion reduces survival and growth in developing zebrafish

Malathion is an organophosphorous pesticide widely used to control mosquitoes in urban areas and pests, such as boll weevils, in agricultural areas. Zebrafish, Danio rerio, are model organisms for developmental toxicology research because they are readily available, produce large numbers of clear embryos, and are sensitive to environmental changes. The nonlethal effects of malathion on developing zebrafish embryos, however, previously have not been analyzed quantitatively. We exposed zebrafish embryos to sublethal malathion concentrations to determine malathion's effects on a developing vertebrate. Zebrafish exposed to 0.5, 1.0, or 1.5 mg/L of malathion consistently elicited more rapid hatching from the chorion than zebrafish exposed to 2.0-, 2.5-, or 3.0-mg/L malathion concentrations. In addition, exposure to 2.0, 2.5, or 3.0 mg/L of malathion resulted in significantly shorter body length and eye diameters, indicating that malathion had teratogenic effects on zebrafish embryos. Malathion's action as an acetylcholinesterase inhibitor and the toxicity of the metabolites of malathion may be responsible for malathion's teratogenic effects on fish development.     

Effect of carbon nanotubes on developing zebrafish (Danio rerio) embryos

The impact of carbon nanotubes (CNTs) on the aquatic environment was investigated by examining the properties of raw CNTs under several environmental conditions and using developing zebrafish (Danio rerio) embryos. The agglomerate size for single-walled CNTs (SWCNTs) was significantly larger at pH 11 or greater and was stable at temperatures from 4 to 40 degrees C and salinities from 0 to 30 ppt. Exposure to SWCNTs induced a significant hatching delay in zebrafish embryos between 52 to 72 h postfertilization (hpf) at concentrations of greater than 120 mg/L, but 99% of the exposed embryos hatched by 75 hpf. Double-walled CNTs also induced a hatching delay at concentrations of greater than 240 mg/L, but carbon black did not affect hatching at the concentrations tested. Molecular and cellular analysis showed that the embryonic development of the exposed embryos up to 96 hpf was not affected at SWCNT concentrations of up to 360 mg/L. Scanning-electron microscopic inspection showed that the size of the pores on the embryo chorion was nanoscaled and that the size of SWCNT agglomerates was microscaled or larger, indicating that the chorion of zebrafish embryos was an effective protective barrier to SWCNT agglomerates. The hatching delay observed in this study likely was induced by the Co and Ni catalysts used in the production of SWCNTs that remained at trace concentrations after purification. This study suggests that materials associated with raw SWCNTs (perhaps metal contaminants) have the potential to affect aquatic life when released into the aquatic environment.     

Toxicity of Guthion® and Guthion® 2S to Xenopus laevis embryos

The development of Xenopus laevis (African clawed frog) embryos exposed to the pesticide Guthion^® (technical grade) and Guthion^® 2S (commercial formulation) was evaluated in modified Frog Embryo Teratogenesis Assay—Xenopus (FETAX) tests. The embryos were exposed to five or six increasing concentrations of pesticide in 10- and 100-ml exposure volumes of test solution for 96 h. Embryos exposed in 10-ml volumes of Guthion exhibited increased mortality, increased deformation, and decreased size as compared to those exposed in 100-ml volumes. LC50s for embryos exposed in the 10-ml Guthion tests ranged from 6.1 to 6.3 mg/L as compared to 10.6 to 11.9 mg/L for those in the 100-ml tests. The percentage of deformities at 3 mg/L Guthion in test survivors in 10-ml tests ranged from 73 to 89%, while in the 100-ml tests less than 2% were deformed at the same concentration. Mean control embryo lengths at test completion were 8.2 and 10.6 mm, respectively, for 10- and 100-ml tests. The LC50 for embryos in 100 ml Guthion 2S was 1.6 mg/L active ingredient, indicating a much greater toxicity of the commercial formulation. NOAEL (No Observed Adverse Effect Level) values for Guthion and Guthion 2S ranged from 0.48 to 7.96 mg/L, depending upon basis (length, deformity, mortality) and pesticide formulation, and were many times greater than the existing water quality criterion of 0.01 g/L.     

Genotoxicity of acute and chronic gamma-irradiation on zebrafish cells and consequences for embryo development

The effects of radiation on biological systems have been studied for many years, and it is now accepted that direct damage to DNA from radiation is the triggering event leading to biological effects. In the present study, DNA damage induced by acute or chronic irradiation was compared at the cellular (zebrafish [Danio rerio] cell line ZF4) and developmental (embryo) levels. Zebrafish ZF4 cells and embryos (at 3 h postfertilization) were exposed within ranges of acute doses (0.3-2 Gy/d) or chronic dose rates (0.1-0.75 Gy/d). DNA damage was assessed by immunodetection of γ-H2AX and DNA-PK (DNA double-strand breaks) and the alkaline comet assay (DNA single-strand breaks). Zebrafish embryo development and DNA damage were examined after 120 h. At low doses, chronic irradiation induced more residual DNA damage than acute irradiation, but embryo development was normal. From 0.3 Gy, a hyper-radiosensitivity phenomenon compared to other species was shown for acute exposure with an increase of DNA damage, an impairment of hatching success, and larvae abnormalities. These results suggest a dose-dependent correlation between unrepaired DNA damage and abnormalities in embryo development, supporting the use of DNA repair proteins as predictive biomarkers of ionizing radiation exposure. This could have important implications for environmental protection.     

Developmental toxicity in zebrafish (Danio rerio) embryos after exposure to manufactured nanomaterials: buckminsterfullerene aggregates (nC60) and fullerol

The present paper summarizes, to our knowledge, the first study regarding the developmental toxicity of stable buckminsterfullerene aggregates suspended in water (nC60) using zebrafish (Danio rerio) as a vertebrate model. Zebrafish embryo survival, hatching rate, heartbeat, and pericardial edema were noted and described within 96 h of exposure. Fullerol (a hydroxylated C60 derivative, C60(OH)16-18) at 50 mg/L did not exert toxicity to zebrafish embryos. In contrast, nC60 at 1.5 mg/L delayed zebrafish embryo and larval development, decreased survival and hatching rates, and caused pericardial edema. Toxicity was mitigated by adding an antioxidant (glutathione), which suggests that a free radical-induced mechanism or another form of oxidative stress played a role in developmental toxicity.     

Al(NO_3)_3对大鼠胚胎的发育毒性研究

应用体外全胚胎培养方法 ,以Al(NO3) 3为受试物 ,培养基中Al3+ 浓度为 0 6～ 9 0 μg ml,直接染毒旋转培养的大鼠胚胎 48h ,观察Al(NO3) 3对大鼠胚胎生长发育和形态分化的影响 ,以探讨铝的胚胎发育毒性及其机理。结果发现 ,随着铝剂量增加 ,胚胎生长发育和器官分化的各项指标均呈现下降趋势 ,有一定的剂量 效应关系。其中 ,胚胎卵黄囊、神经管及心脏分化发育等对铝的作用较为敏感 ,相关指标在Al3+ 浓度为1 2 μg ml时比对照组显著降低 (P <0 0 5 )。≥ 3 0 μg ml时 ,除下颌外各项指标均明显降低 (P <0 0 5或P <0 0 1) ,同时胚胎畸形发生率明显升高 ,畸形以神经管闭合不全、体屈异常多见。表明Al(NO3) 3可导致胚胎发育迟缓和神经系统等器官发育畸形。     

Hormetic Versus Toxic Effects of Vegetable Tannin in a Multitest Study

Tannin from mimosa trees (Acacia sp.) utilized in traditional leather tanning was tested for toxicity in sea urchin (Sphaerechinus granularis and Paracentrotus lividus) embryos and sperm, marine, and freshwater algae (Selenastrum capricornutum and Dunaliella tertiolecta), and Daphnia magna. Based on a two-step tanning procedure used in traditional tanneries, two mimosa tannin preparations, i.e., fresh tannin (FT) and used tannin (UT), were tested as suspensions. The early results in S. granularis embryos showed that UT exerted lower acute toxicity than FT, namely, 1 vs 100 mg/L, to obtain 100% mortality, respectively. Subsequent bioassays were conducted on fresh tannin water extracts (TWE) corresponding to nominal tannin concentrations ranging from 0.1 to 30 mg/L. Developmental toxicity, up to embryonic mortality was exerted by TWE at levels >1 mg/L, S. granularis being more sensitive than P. lividus embryos/larvae. At the concentration of 0.1 mg/L, the frequencies of larval malformations were significantly lower than in controls. This positive stimulatory effect (currently termed as hormesis) was observed in extended numbers of culture replicates (up to 14) and was significant in the embryo cultures characterized by a relatively poor control quality (with <70% viable larvae in controls), whereas this effect was not observed in good-quality cultures (with 70% viable larvae in controls). Cytogenetic analysis of S. granularis embryos reared in FT or UT suspensions (1 mg/L to 1 g/L) showed mitotoxic effects (decrease in active mitoses per embryo) in FT-exposed, but not in UT-exposed embryos. Mitotic aberrations were significantly increased by 10 mg/L UT. Sperm fertilization success in both sea urchin species showed an increasing fertilization rate (FR) up to 0.3 mg/L TWE and a dose-related decrease in FR up to 30 mg/L. Again, the offspring of P. lividus sperm exposed to TWE (0.1 and 0.3 mg/L) showed a decrease in larval malformations compared to controls, whereas a dose-related increase in developmental defects was observed in the offspring of P. lividus sperm exposed to higher TWE levels (1 to 30 mg/L). Algal cell growth bioassays in two species (S. capricornutum and D. tertiolecta) also showed a maximum growth at TWE levels ranging from 0.3 to 3 mg/L and a subsequent decline up to 30 mg/L TWE. D. magna bioassays resulted in daphnid immobilization by TWE concentrations ranging from 100 to 300 mg/L. The results demonstrate that tannins utilized in traditional leather tanning industry may raise concern of environmental damage at relatively high concentrations, whereas low-level tannins may result in hormetic effects. The present study also points to the need for bioassay design that should rely on adequate criteria in control quality, allowing to detect both inhibitory and hormetic effects.