Robust benchmark dose determination based on profile score methods

We investigate several methods commonly used to obtain a benchmark dose and show that those based on full likelihood or profile likelihood methods might have severe shortcomings. We propose two new profile likelihood-based approaches which overcome these problems. Another contribution is the extension of the benchmark dose determination to non full likelihood models, such as quasi-likelihood, generalized estimating equations, which are widely used in settings such as developmental toxicity where clustered data are encountered. This widening of the scope of application is possible by the use of (robust) score statistics. Benchmark dose methods are applied to a data set from a developmental toxicity study.     

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.     

Cr(Ⅵ)对脊尾白虾(Exopalaemon carinicauda)幼虾暴露和恢复期肝胰脏的SOD活性、MDA及MTs含量的影响

为了探索水体中Cr(Ⅵ)对脊尾白虾(Exopalaemon carinicauda)的毒性效应,通过Cr(Ⅵ)的暴露(15 d)和清水恢复实验(15d),研究了Cr(Ⅵ)对脊尾白虾肝胰脏的SOD活性、MDA及MTs含量的影响.结果表明,通过15 d的暴露,5 mg·L-1(高浓度)、0.5 mg· L-1(低浓度)实验组肝胰脏的SOD均显著高于对照组水平(p＜0.05),15 d的清水恢复后,两个浓度实验组均能够恢复到对照组水平(p＞0.05).MDA在暴露阶段呈现持续上升的趋势,且在15 d后两个浓度实验组MDA的含量均显著高于对照组水平(p＜0.05),15 d的清水恢复后,5mg·L-1实验组的MDA含量依然显著高于对照组水平(p＜0.05),0.5mg·L-1实验组的MDA含量基本恢复到对照组水平(p＞0.05).通过15 d的暴露,两个浓度实验组MTs的含量均显著高于对照组水平(p＜0.05),15 d的清水恢复后,两个浓度实验组MTs的含量均能够恢复到对照组水平(p＞0.05).     

Assessing the chemical and biological accessibility of the herbicide isoproturon in soil amended with biochar

Decamethylcyclopentasiloxane (D5) is a cyclic volatile methyl siloxane (cVMS) commonly found in commercially available products. D5 is expected to enter the terrestrial environment through the deposit of biosolids from sewage treatment plants onto agricultural fields for nutrient enrichment. Little to no information currently exists as to the risks of D5 to the terrestrial environment. In order to evaluate the potential risk to terrestrial organisms, the toxicity of a D5 contaminated biosolid in an agricultural soil was assessed with a battery of standardized soil toxicity tests.D5 was spiked into a surrogate biosolid and then mixed with a sandy loam soil to create test concentrations ranging from 0 to 4074 mg kg⁻¹. Plant (Hordeum vulgare (barley) and Trifolium pratense (red clover)) and soil invertebrates (Eisenia andrei (earthworm) and Folsomia candida (springtail)) toxicity tests were completed to assess for lethal and sub-lethal effects. Plant testing evaluated the effects on seedling emergence, shoot and root length, and shoot and root dry mass. Invertebrate test endpoints included adult lethality, juvenile production, and individual juvenile dry mass (earthworms only). Soil samples were collected over time to confirm test concentrations and evaluate the loss of chemical over the duration of a test. The toxicity of the D5 was species and endpoint dependent, such that no significant adverse effects were observed for T. pratense or E. andrei test endpoints, however, toxicity was observed for H. vulgare plant growth and F. candida survival and reproduction. Chemical losses of up to 50% were observed throughout the tests, most significantly at high concentrations.     

Clinical and toxicological data in Fenthion and omethoate acute poisoning

Abstract

This study paper reports on two cases of poisoning with the organophosphorus insecticides, fenthion and omethoate. The two victims were admitted in the Intensive Care Unit (ICU) a few hours after ingestion of the two insecticides. They received appropriate treatment for organophosphorous poisoning (gastric lavage, activated charcoal, atropine and pralidoxime) and supportive care. Both patients survived. Organophosphate blood levels were determined on admission (fenthion 2.9 (ig/ml, omethoate 1.6 Hg/ml) and during the hospitalisation and proved to be considerably high. Slow elimination rate of the poison already distributed in the body was indicated for both pesticides. The patient with omethoate poisoning remained clinically well (Glasgow Coma Scale : 15) and was discharged three days later. The patient with fenthion poisoning, who had also ingested 30 mg of bromazepam and 720 mg of oxetoron, developed cholinergic crisis six hours after admission and was intubated for 24 days, with concomitant complications.     

Studying developmental neurotoxic effects of bisphenol A (BPA) using embryonic stem cells

There is little to no toxicity information regarding thousands of chemicals to which people are exposed daily. In fact, of the 84,000 chemicals listed in the United States Toxic Substances Control Act Inventory, there is limited information available on their effects on neural development (Betts, 2010 and US EPA, 2015). The number of chemicals tested remains low due to the high cost of conducting multi-generational animal studies and the lack of alternative testing methods.     

TOXIC EFFECTS OF PETROLEUM AND SHALE JP-4 AND JP-8 AVIATION FUELS ON FATHEAD MINNOWS1

ABSTRACT: Static 96-hour median lethal concentrations were determined for the water-soluble fraction (WSF) of both petroleum-derived and shale-derived avaiation fuels (JP-4 and JP-8) using fathead minnows. JP-8 was more toxic than JP-4 except for one shale JP-4 sample that was as toxic as the JP-8. Petroleum and shale JP-8 were similar in toxicity. The toxicity of shale JP-4 was less clear. Shale JP-4 from three vendor sources revealed differing toxicity values. One shale JP-4 sample was more toxic and one less toxic than its petroleum analogue, with the third being equally toxic. Toxicity of the fuels may be enhanced by compounds in the WSF that correspond to chemicals containing 10 or more carbon atoms.     

THE CASE FOR DIRECT MEASUREMENT OF ENVIRONMENTAL RESPONSE TO HAZARDOUS MATERIALS1

ABSTRACT: Direct measurement of response thresholds of complex biological systems to toxic chemicals is now possible using microcosms and other simulation techniques. Extrapolation to no-observable response using application factors and data from single species toxicity tests is less precise than direct measurements.     

应用体内和体外方法评价原油水溶性组分和原油污染的地表水对淡水生物的内分泌干扰潜力

目前关于原油对淡水水生脊椎动物内分泌信号的潜在影响的认知有限。本文以非洲爪蟾(爪蟾属,X. laevis)蝌蚪和莫桑比克罗非鱼幼鱼(口孵非鲫属,O. mossambicus)为研究对象,选择风化原油和未风化提炼后的原油这2种原油的水溶性组分(WAFs)进行暴露实验,选择出可作为内分泌信号改变的生物标志物的基因,对其表达进行了研究。此外,将X. laevis蝌蚪暴露于靠近地下石油库的地表水中,对上述基因表达做了定量分析。利用重组酵母对原油、原油水溶性组分和地表水的(抗)雌激素和(抗)雄激素性进行了评价。在X. laevis对2种原油WAFs的响应中,甲状腺激素受体β表达均显著下调,而另一种与甲状腺相关的基因,2型脱碘酶,在O. mossambicus暴露于高浓度的原油WAF时被上调。此外,这2种WAFs都改变了与脂肪生成相关的过氧化物酶体增殖物激活受体γ在X. laevis中的表达。原油和WAFs在体外表现出抗雌激素和抗雄性激素的活性。然而,O. mossambicus雄激素受体2作为唯一一个代表生殖系统的基因,受到WAF暴露的影响显著。在地表水样品中发现了雌激素、抗雌激素和抗雄激素的作用;但是,在暴露于地表水的X. laevis中没有观察到任何基因表达的明显变化。在所用的2种模式生物以及2种原油中,响应各不相同。尽管如此,这些数据提供了证据证明原油污染可能会因内分泌信号转变对淡水鱼和两栖动物的健康造成不利影响。
精选自Truter, J. C., van Wyk, J. H., Oberholster, P. J., Botha, A.-M. and Mokwena, L. M. (2017), An evaluation of the endocrine disruptive potential of crude oil water accommodated fractions and crude oil contaminated surface water to freshwater organisms using in vitroand in vivo approaches. Environmental Toxicology and Chemistry, 36: 1330–1342. doi: 10.1002/etc.3665
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3665/full
     

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。