A comparative study of the toxicity of lead and its impact on the carbohydrate metabolism and some haematological parameters of cichlid fish,oreochromis niloticus and catfish,clarius gariepinus from saudi arabia

Fresh and healthy specimens of Oreochromis niloticus (mean weight 70.5± 1.23 g and mean length, 12.3± 1.5cm) and Clarias gariepinus (mean weight, 41.8±2.3 g and mean length 13.78 ± 1.2 cm) were exposed to heavy metal lead, ranging in concentration from 10 to 18 mg L^‐1 for O. niloticus and 20 to 28 mg L^‐1 for C. gariepinus respectively. The 96 h LC₅₀ for both the species was computed as 12.45 mg L^‐1 (O. niloticus) and 22.65 mg L^‐1 (C. gariepinus). The cichlid fish was exposed to sublethal concentration of lead (2, 4 and 6 mgL^‐1) and catfish (4, 8 and 12 mgL^‐1). The erythrocytes count, haemoglobin concentration, haematocrit and the value of serum glucose increased significantly (P < 0.01), whereas leucocytes count, serum protein and serum triglyceride after intoxication declined in both the species with the same pattern but in different quantity. After 96 h of time a significant depletion of muscle and liver glycogen was noted, being greater in muscle (16.7% in O. niloticus) and in liver (15.9% in C. gariepinus). The response of fish to lead was dose dependent.     

Fluoride contamination in groundwater of central Rajasthan,India and its toxicity in rural habitants

This study was carried out to assess fluoride (Fl) concentration in groundwater in some villages of central Rajasthan, India, where groundwater is the main source of drinking water. Water samples collected from deep aquifer-based hand pumps were analyzed for Fl content. Fluoride in groundwater of 121 habitations of Bhilwara tehsil of Bhilwara district of Rajasthan was determined to examine the potential Fl-induced toxicity in rural locations. Fluoride concentrations in the tehsil ranged from 0.5 to 5.8 mg/l. In the tehsil, 69 villages (57%) were found to have Fl concentration beyond the maximum desirable limit recommended in Bureau of Indian Standards (BIS), 10500, 1991. Fifty-eight percent population of these villages was under the threat of fluorosis. One percent population of tehsil living in two villages ingested more than 5 mg/l Fl in each liter of drinking water and at maximal risk for dental and skeletal fluorosis. 142 individuals of these villages were examined for fluorosis. Data indicated that only four individuals (2.82%) did not exhibit dental fluorosis. Most individuals were found to suffer from mild (34.51% or 49 individuals) and moderate (31.69% or 45 individuals) fluorosis. Severe dental fluorosis was recorded in only 16 individuals (11.27%). In 104 individuals above 21 years of age examined for the prevalence of skeletal fluorosis, 66 were positive for skeletal fluorosis with a maximum 36.5% with grade I skeletal fluorosis. Grade II skeletal fluorosis was recorded in 28 individuals (26.9%). Data in this study demonstrate that there is a need to take ameliorative steps in this region to prevent fluorosis.     

典型氯酚类化合物对水生生物的毒性研究进展

氯酚类化合物(CPs)是一类广泛存在于水环境中的有机污染物。这类化合物具有环境稳定性、生物累积性和生物毒性,因而其在水环境中的生态毒理效应一直是人们关注的焦点。在水体中存在最普遍的酚类化合物主要有2,4-二氯酚(2,4-DCP),2,4,6-三氯酚(2,4,6-TCP)和五氯酚(PCP)。本文对近几年来这3种典型氯酚类化合物的水生态毒理学研究进行了总结,主要包括它们对水生生物的急性毒性、氧化损伤、发育毒性、内分泌干扰、遗传毒性、致癌性、免疫毒性、细胞毒性以及复合毒性的效应和机制,同时对目前存在的问题和进一步的研究方向进行了讨论和展望。     

淡水沉积物的生物测试方法研究

描述了淡水沉积物毒性的生物测试方法。沉积物基质可以通过直接采样法和掺入法制备,储存会影响其生物可利用性。全底泥相,间隙水相和复溶相是目前沉积物毒理学研究常用的试验相,其中,间隙水相被认为是进行沉积物毒理学研究较为理想的试验相。同时推荐采用离心法制备间隙水。此外,为增加试验结果的可比性,文中还讨论了试验生物的选择问题。      

火灾中建材燃烧毒性的试验研究

通过探讨火灾中燃烧毒性对人体的危害和分析国外主要的毒性研究方法，研制了毒气热分解仪并对部分有一定代表性的建材进行了实测研究。根据研究结果提出了相应的结论意见。     

二恶英类毒理学研究新进展

二恶英类的毒理学研究已有30多年的历史,在一系列二恶英类污染事件和国际公约的推动下,近年来二恶英类毒理学研究成为备受关注的热点.综述了近年来二恶英类毒理学研究的一些新的观点和发现,涵盖了分子毒性机理、致癌毒性、非致癌毒性和非致癌剂量-效应风险度评价方法等诸多领域,其中TCDD毒性效应的负反馈调节机制研究和对人体健康非致癌效应的影响引起了国内外广大毒理学研究工作者的关注.在总结前人研究的基础上对二恶英类毒理学研究今后的发展进行了展望.     

腐殖酸可降低纳米银的水生生物毒性

本文作者主要研究了腐殖酸对聚乙烯吡咯烷酮包覆的纳米银颗粒(polyvinylpyrrolidone-coated AgNPs)毒性的影响，受试生物涵盖了水生系统不同的营养级别，包括藻类(Raphidocelis subcapitata)、水蚤类(Chydorus sphaericus)以及淡水鱼类(Danio rerio)。结果显示，腐殖酸可降低AgNPs对本研究中所有水生生物的毒性，并具有明显的剂量效应关系。原因为：1）腐殖酸使AgNPs表面带有更多负电荷，这阻碍了AgNPs与藻细胞的接触，使毒性降低；2）腐殖酸抑制了AgNPs中Ag⁺的溶出，而本研究显示自由Ag⁺的毒性高于团聚的纳米银颗粒。
精选自Zhuang Wang, Joris T.K. Quik, Lan Song, Evert-Jan Van Den Brandhof, Marja Wouterse and Willie J.G.M. Peijnenburg. Humic substances alleviate the aquatic toxicity of polyvinylpyrrolidone-coated silver nanoparticles to organisms of different trophic levels. Environmental Toxicology and Chemistry: Volume 34, Issue 6, pages 1239–1245, June 2015. DOI: 10.1002/etc.2936
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.2936/full
     

农药暴露的机制模型：蜜蜂毒理学的重要缺失

杀虫剂在最近的蜜蜂数量减少中所扮演的角色是有争议的，部分原因是实地研究常常无法检测到实验室研究所预测的效果。这种不一致性突出了蜜蜂毒理学研究领域的一个关键空白：对蜜蜂在它们的环境中杀虫剂暴露的模式和过程知之甚少。本文作者提出蜜蜂暴露杀虫剂的2个关键过程：1)工蜂采集花蜜的过程中收集农药；2)工蜂带回的农药在蜂巢中的再分配。工蜂收集农药的过程必须被理解为环境污染和蜜蜂觅食活动之间的时空交集。这意味着农药暴露是分配的，而不是离散的，觅食工蜂的一个子集可能会获得有害剂量的农药，而群体暴露将会显得安全。蜂箱中农药的分布是一个复杂的过程，主要是由群体成员之间食物转移的相互作用而产生，而这一过程中花粉和花蜜之间有重要的区别。因此应该优先将关于蜜蜂生物学的大量文献用于发展更严谨的蜂蜜农药暴露机制模型。与效应机制模型结合，暴露机制模型具有整合蜜蜂毒理学领域的潜力，以促进风险评估和基础研究。
精选自Sponsler, D. B. and Johnson, R. M. (2017), Mechanistic modeling of pesticide exposure: The missing keystone of honey bee toxicology. Environmental Toxicology and Chemistry, 36: 871–881. doi: 10.1002/etc.3661
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3661/full
     

Price perceptions in water demand

Economists advocate for using the price mechanism to manage water scarcity, but complex nonlinear rate structures prevalent in markets for municipal water obscure price signals. We conduct a randomized field experiment that jointly elicits knowledge about the cost of water and examines the impact of improved information on demand by linking a survey to water billing records. Half of our sample of 30,000 single family homeowners are randomly sent an invitation to a survey that asks questions about the water bill and the costs of water-use activities (e.g. the cost of taking a shower), and subsequently provides personalized accurate information. Results show that consumers have poor information about the marginal price of water and overestimate the costs of using water. Respondents are relatively better informed about their total bill and water consumption. In aggregate, respondents increase water use in response to the survey, potentially due to learning that water is cheaper than they previously thought. Increased consumption is concentrated among low users who are more likely to over-estimate the costs of using water.     

Rapid and sensitive headspace gas chromatographic method for cyanide determination in whole blood

We reported a simple and rapid headspace (HS) gas chromatographic (GC) assay for the determination of cyanide in human whole blood obtained from both cadaveric and intoxicated subjects. The poison was extracted from whole blood samples by HS technique after 10 min incubation at 80°C with a HCl (1N) acidic solution supplemented with 30 g L^?1 of sodium chloride and 10 mg L^?1 of isopropanol as internal standard. A SGE WAX capillary column (30 m × 0.32 mm ID × 0.5 µm df) was used. The Flame Ionization Detector (FID) was set at 250°C. The detection and the quantification limits were 0.02 and 0.2 mg L^?1, respectively. In the within-day study, the coefficients of variation for three different whole blood cyanide concentrations varied between 3.2 and 6.5%, whereas those in the day-to-day study varied between 4.8 and 6.3%. The assay was performed in less than 20 min per sample, which appears to be suitable for emergency toxicological tasks involved in diagnosis of cyanide poisoning.