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Toxicity Levels (toxicity + level)
Selected AbstractsAcute toxicity to zebrafish of two organophosphates and four pyrethroids and their binary mixturesPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 1 2010Zhi-Yong Zhang Abstract BACKGROUND: Environmental pollutants, including metals, pesticides and other organics, pose serious risks to many aquatic organisms. The acute toxicities to zebrafish (Brachydanio rerio Hamilton & Buchanan) were determined for two organophosphorus insecticides, four pyrethroid insecticides and 50:50 binary mixtures. RESULTS: At 24, 48, 72 and 96 h after treatment, LC50 of permethrin, tetramethrin, bifenthrin, etofenprox, dichlorvos and phoxim to zebrafish were 0.0052,0.0025, 0.0782,0.0460, 0.0065,0.0032, 0.0969,0.0791, 51.3,13.0 and 1.28,0.469 mg L,1 respectively. LC50 of permethrin + dichlorvos, permethrin + phoxim, tetramethrin + dichlorvos, tetramethrin + phoxim, bifenthrin + dichlorvos, bifenthrin + phoxim, etofenprox + dichlorvos and etofenprox + phoxim were 0.0082,0.0046, 0.0078,0.0042, 0.264,0.124, 0.141,0.121, 0.0251,0.0154, 0.0154,0.0087, 0.396,0.217 and 0.213,0.0391 mg L,1. CONCLUSION: Toxicity levels of all pyrethroid insecticides to the zebrafish were high or very high. The organophosphate dichlorvos showed low toxicity, but phoxim showed high or intermediate toxicities to zebrafish, and the toxicities of binary mixtures of permethrin and dichlorvos or phoxim, bifenthrin and dichlorvos or phoxim and etofenprox and phoxim (48, 72 and 96 h exposure) were very high. The toxicities of binary mixtures of tetramethrin and dichlorvos or phoxim, etofenprox and dichlorvos and etofenprox and phoxim (24 h exposure) were high. Copyright © 2009 Society of Chemical Industry [source] Acute toxicity and bioaccumulation of pesticide Diazinon in red tilapia (Oreochromis niloticus x Mossambicus albina)ENVIRONMENTAL TOXICOLOGY, Issue 4 2002Jaime A. Palacio Abstract Young red tilapias were exposed for 96 h to each one of 6 concentrations of the pesticide Diazinon in order to determine the pesticide's acute toxicity level. After the ascertaining the lethal concentration (LC50) at 96 h, a level 10 times lower was selected for the bioaccumulation study of the pesticide in male and female specimens exposed for 9 days. The elimination process was carried out for 10 days beginning right after the conclusion of the accumulation process. Analytical procedures were developed and used for the studies of acute toxicity and bioaccumulation of Diazinon in red tilapia. A lethal concentration [LC50 (96 h)] of 3.85 mg/L was found, and steady-state accumulation, at a concentration of 28.45 mg/kg, was reached at 7.72 days. In the elimination process a concentration of 0.29 mg/kg was found in tilapia tissue by the sixth day after the fish were moved to clean water, and it continued to decrease quickly toward nondetectable levels. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 334,340, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10063 [source] A phase II study of gemcitabine and docetaxel therapy in patients with advanced urothelial carcinomaCANCER, Issue 9 2003Barbara J. Gitlitz M.D. Abstract BACKGROUND The objectives of the current study were to evaluate the safety and efficacy of gemcitabine plus docetaxel in patients with unresectable (Stage T4 or , N1) metastatic or locally advanced transitional cell carcinoma (TCC) of the urothelial tract. METHODS A total of 27 patients were enrolled in the current multisite study, which was performed within the University of California-Los Angeles Community Oncology Research Network. The first 10 patients in the study received 800 mg/m2 of gemcitabine intravenously on Days 1, 8, and 15 of a 28-day treatment cycle. In addition, on Day 1, the first 10 patients received 80 mg/m2 of docetaxel intravenously after completion of the gemcitabine infusion. Because of dose-limiting toxicity (neutropenia), the initial dose of docetaxel was reduced to 60 mg/m2 for the remaining patients who entered the study (n = 17 patients). RESULTS Neutropenia was the most common adverse event that occurred in patients at the Grade 3 level (in 10 of 27 patients; 37.0%) and the Grade 4 level (in 6 of 27 patients; 22.2%). There were no other adverse events at the Grade 4 toxicity level. Twenty-five of 27 patients (92.6%) completed more than 1 cycle of combination therapy and were evaluated for antitumor responses. The frequency of objective clinical responses was 33.3% (9 of 27 patients). Complete responses to therapy were observed in 2 of 27 patients (7.4%), and partial responses were observed in 7 of 27 patients (25.9%). The median duration of response was 20 weeks (range, 12+ weeks to 152 weeks). The median survival duration was 52 weeks (range, 12 weeks to 160+ weeks). Four of 27 patients (14.8%) remained alive at the time of the current data analysis. CONCLUSIONS The results of the current study suggested that combination therapy with gemcitabine and docetaxel was an effective treatment for patients with unresectable (Stage T4 or , N1) metastatic or locally advanced TCC of the urothelial tract. Gemcitabine plus docetaxel appeared to be tolerated well, and treatment-related toxicities were limited to hematologic toxicities. Because cisplatin-containing regimens are contraindicated for patients with impaired renal function, the gemcitabine plus docetaxel combination may prove to be an effective and well tolerated treatment option for these patients. Cancer 2003. © 2003 American Cancer Society. [source] Diversity of native and alien plant species on rubbish dumps: effects of dump age, environmental factors and toxicityDIVERSITY AND DISTRIBUTIONS, Issue 3 2003Antonín Py Abstract. The flora of 96 rubbish dumps consisting of organic, inorganic and industrial wastes was studied in the Czech Republic. Some dumps contained toxic substances (heavy metals, chlorethylenes, phenols, polychlorinated biphenyls, oil hydrocarbons and biogas). Statistically significant factors explaining the number and proportional representation of native plant species, archaeophytes (introduced before 1500) and neophytes (introduced later) were determined. In total, 588 species of vascular plants were recorded, with archaeophytes (133 species) over-represented and native species (322 species) and neophytes (133 species) under-represented compared to their proportions in the national flora. Minimum adequate models were used to determine the effects of several factors on species numbers and proportions, independent of other factors. Dump area, human density in the region and altitude (non-significant only in archaeophytes) were correlated positively with species numbers. Dump age, expressed as time since dump establishment, interacted with the dump toxicity; species numbers increased with dump age on non-toxic dumps, whereas on toxic dumps no increase in numbers was noted. For neophytes, dump toxicity also interacted with human density; the increase in numbers of neophytes with human density is more pronounced on toxic than on non-toxic dumps. The variables measured failed to explain observed differences in proportional representation of native species, archaeophytes and neophytes. This suggests that the occurrence of species growing in such extreme habitats is driven overwhelmingly by factors such as anthropogenic disturbance. A possible explanation for the positive effect of altitude on species numbers on dumps is that the effect of heating of the deposited substrate by microbiological processes, documented by previous studies, overrides the effect of altitude which was shown repeatedly to have a negative effect on species richness. Neophyte distribution is driven by an interplay of factors distinct from those influencing the distribution of native species, namely toxicity and human density (the latter we interpret as a surrogate for propagule pressure). Their distribution on studied dumps is more restricted than that of native taxa and archaeophytes, and they are more limited by toxic substrata; more intensive propagule pressure is required for their establishment at dumps with higher toxicity levels. [source] Acute toxicity of heavy metals to acetate-utilizing mixed cultures of sulfate-reducing bacteria: EC100 and EC50ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2001Vivek P. Utgikar Abstract Acid mine drainage from abandoned mines and acid mine pit lakes is an important environmental concern and usually contains appreciable concentrations of heavy metals. Because sulfate-reducing bacteria (SRB) are involved in the treatment of acid mine drainage, knowledge of acute metal toxicity levels for SRB is essential for the proper functioning of the treatment system for acid mine drainage. Quantification of heavy metal toxicity to mixed cultures of SRB is complicated by the confounding effects of metal hydroxide and sulfide precipitation, biosorption, and complexation with the constituents of the reaction matrix. The objective of this paper was to demonstrate that measurements of dissolved metal concentrations could be used to determine the toxicity parameters for mixed cultures of sulfate-reducing bacteria. The effective concentration, 100% (EC100), the lowest initial dissolved metal concentrations at which no sulfate reduction is observed, and the effective concentration, 50% (EC50), the initial dissolved metal concentrations resulting in a 50% decrease in sulfate reduction, for copper and zinc were determined in the present study by means of nondestructive, rapid physical and chemical analytical techniques. The reaction medium used in the experiments was designed specifically (in terms of pH and chemical composition) to provide the nutrients necessary for the sulfidogenic activity of the SRB and to preclude chemical precipitation of the metals under investigation. The toxicity-mitigating effects of biosorption of dissolved metals were also quantified. Anaerobic Hungate tubes were set up (at least in triplicate) and monitored for sulfate-reduction activity. The onset of SRB activity was detected by the blackening of the reaction mixture because of formation of insoluble ferrous sulfide. The EC100 values were found to be 12 mg/L for copper and 20 mg/L for zinc. The dissolved metal concentration measurements were effective as the indicators of the effect of the heavy metals at concentrations below EC100. The 7-d EC50 values obtained from the difference between the dissolved metal concentrations for the control tubes (tubes not containing copper or zinc) and tubes containing metals were found to be 10.5 mg/L for copper and 16.5 mg/L for zinc. Measurements of the turbidity and pH, bacterial population estimations by means of a most-probable number technique, and metal recovery in the sulfide precipitate were found to have only a limited applicability in these determinations. [source] Sampling Strategies for Volatile Organic Compounds at Three Karst Springs in TennesseeGROUND WATER MONITORING & REMEDIATION, Issue 1 2006Shannon D. Williams The influence of different sampling strategies on characterizing volatile organic compound (VOC) concentrations and estimating VOC loads was evaluated at three karst springs in Tennessee. During a 6-month period, water samples for VOC analyses were collected weekly at all three springs and as frequently as every 20 min during storms at the two springs with variable water quality conditions. Total 6-month loads for selected VOCs were calculated, and VOC data were systematically subsampled to simulate and evaluate several potential sampling strategies. Results from the study indicate that sampling strategies for karst springs need to be developed on a site-specific basis. The use of fixed sampling intervals (as infrequently as quarterly or semiannually) produced accurate concentration and load estimates at one of the springs; however, additional sampling was needed to detect storm-related changes at a second spring located in a similar hydrogeologic setting. Continuous discharge data and high-frequency or flow-controlled sampling were needed at the third spring, which had the most variable flow and water quality conditions. The lack of continuous discharge data at the third spring would substantially affect load calculations, and the use of fixed sampling intervals would affect load calculations and the ability to detect pulses of high contaminant concentrations that might exceed toxicity levels for aquatic organisms. [source] The retail market for fresh cassava root tubers in the European Union (EU): the case of Copenhagen, Denmark , a chemical food safety issue?JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 2 2010Lotte Kolind-Hansen Abstract BACKGROUND: A number of retail shops in Copenhagen sell fresh cassava roots. Cassava roots contain the toxic cyanogenic glucoside linamarin. A survey was made of the shop characteristics, origin of the roots, buyers, shop owner's knowledge of toxicity levels, and actual toxicity levels. RESULTS: Shops selling fresh cassava were shown mostly to be owned by persons originating in the Middle East or Afghanistan, buyers were found to predominantly be of African origin, and sellers' knowledge concerning the potential toxicity was found to be very restricted. Seventy-six per cent of the roots purchased had a total cyanogenic potentials (CNp) above the 50 mg HCN equivalents kg,1 dry weight (d.w.) proposed as acceptable by an EU working group. Two of 25 roots purchased had CNp higher than 340 mg HCN eq. kg,1 d.w. CONCLUSION: The EU has previously made risk assessments concerning cassava and cyanogenic compounds. In the light of the conclusions drawn, the EU needs to make decisions about how to deal with the regulation and control of fresh cassava roots imported to the European food market. Also cassava root products and cassava leaves should be considered. Copyright © 2009 Society of Chemical Industry [source] High-dose 131I-metaiodobenzylguanidine therapy for 12 patients with malignant pheochromocytomaCANCER, Issue 2 2003Brian Rose M.D. Abstract BACKGROUND 131I-Metaiodobenzylguanidine (131I-MIBG) can be used systemically to treat malignant pheochromocytoma. To improve outcome, the authors used higher levels of activity of 131I-MIBG than previously reported. The authors reported the response rates and toxicity levels in patients with malignant pheochromocytoma or paraganglioma who were treated with high-dose 131I-MIBG. METHODS Following debulking surgery and stem cell harvest, 12 patients with malignant pheochromocytoma or paraganglioma were treated with 131I-MIBG. Five had received previous external beam radiation and/or chemotherapy. The median single treatment dose was 800 mCi (37 gigabecquerels; range, 386,866 mCi) or 11.5 mCi/kg (range, 5.6,18.3 mCi/kg). The median cumulative dose was 1015 mCi (range, 386,1690 mCi). RESULTS Three patients had a complete response, two of whom had soft tissue and skeletal metastases. Their median follow-up was 45 months (range, 23,101 months). Seven patients had a partial response (PR), with a median follow-up 43 months (range, 6,47 months). Two patients without a response died with progressive disease (PD) and 2 patients with an initial PR died of PD at 13 and 11 months, respectively. Grade 3 thrombocytopenia occurred after 79% (15 of 19) of treatments had been administered. Grade 3 and 4 neutropenia followed 53% (10 of 19) and 19% (4 of 19) of treatments, respectively. One patient required stem cell infusion, and one developed primary ovarian failure. CONCLUSIONS The single and cumulative doses of 131I-MIBG were approximately 2,3.5 times higher than those used at other centers. Unlike previous reports, two patients with both skeletal and soft tissue metastases had a complete response. Hematologic toxicity was significant but tolerable. High-dose 131I-MIBG may lead to long-term survival in patients with malignant pheochromocytoma. Cancer 2003;98:239,48. © 2003 American Cancer Society. DOI 10.1002/cncr.11518 [source] | |||||||||||||