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Effect of pH on the persistence and toxicity of cyfluthrin to Chironomus tentans

Description: The effect of pH upon the aquatic toxicity of cyfluthrin was determined in 48 h static acute toxicity tests using 2nd instar Chironomus tentans larvae. Tests were conducted in both dechlorinated tap water and lake water of pH 8.0, 7.2, and 6.6. After 48 h, immobilized and dead larvae were removed and replaced with 2nd instar larvae to assess the persistence of toxicity. Midges were cultured in water adjusted to the pH values used in testing.
Date: May 1992
Creator: Hambleton, Faith Ann (Faith Ann Elizabeth)
Partner: UNT Libraries

The control of beryllium hazards

Description: From abstract: "The toxicological properties of beryllium and compounds of beryllium are briefly reviewed, together with the historical development of the recommendations for maximum permissible beryllium air concentrations. The application of the enclosure technique presently in use at this laboratory for the control of beryllium hazards is described... Monitoring procedures used to evaluate the performance of enclosures are discussed."
Date: July 15, 1959
Creator: Lindeken, C. L. & Meadors, Orville L.
Partner: UNT Libraries Government Documents Department

Effects of Methanol, Atrazine, and Copper on the Ultrastructure of Pseudokirchneriella Subcapitata (Selenastrum Capricornutum).

Description: The toxicity of methanol, atrazine, and copper to Pseudokirchneriella subcapitata (Korshikov) Hindák historically referred to as Selenastrum capricornutum Printz were determined following 96 hrs growth in a modified Goram's growth media. Methanol and atrazine inhibited fluorescence readings in the cultures by 50% (IC50) at concentrations of 2% and 82 µg/l respectively. These toxicity values compared favorably to other published reports. The IC50 for copper was 160 µg/l which is substantially higher than reported values. This is understandable because of the high chelating capacity of Goram's media. The use of stereologically derived relative volume in the chloroplasts, mitochondria, lipid bodies, phosphate bodies, and nucleus was investigated to determine if it could be used as a sensitive endpoint in toxicity tests. The volume fractions for the chloroplasts and mitochondria were normally distributed in control cells while the nuclei, phosphate bodies, and lipid bodies were not. The chloroplasts were the most dominate organelle occupying a mean relative volume of 46% and mitochondria occupied a mean relative volume of 3%. The nucleus and phosphate bodies occupied a median relative volume of 7% and 2% respectively. The lipid bodies were rare in section profile and no meaningful median relative volume could be calculated. Up to the 82nd percentile of sectioned profiles contained no recognizable lipid bodies. The use of relative volume was not a sensitive endpoint for use in toxicity tests. No significant differences in relative volume could be detected in the nucleus or phosphate bodies following any treatment. Limited differences were detected in the mitochondria, chloroplasts, and lipid bodies. The only significant differences that appear to be biologically significant occurred in methanol treated cells where an increase in the lipid bodies' relative volume was apparently concentration dependent. Significant differences in the relative volume of mitochondria and chloroplasts do not appear to be biologically significant.
Date: May 2004
Creator: Garrett, David C.
Partner: UNT Libraries

Passive smoking in the workplace: selected issues: staff paper

Description: Three major areas are covered in this Staff Paper: 1) a review of the studies of health effects related to passive smoking; 2) a review of current Federal, State and local, and private sector workplace smoking policies; and 3) a discussion of factors to consider in an analysis of the costs and benefits of implementing a workplace smoking policy.
Date: May 1986
Creator: United States. Congress. Office of Technology Assessment.
Partner: UNT Libraries Government Documents Department

Uranium Tetrachloride Two One-Year Inhalation Toxicity Studies of Animals at 0.2 and 0.05 mg U/m3

Description: The following report analyzes studies of chronic inhalation toxicity from uranium tetrachloride dust in animals who were exposed daily for a year for the purpose of determining "borderline" or safe levels of exposure for the duration of one year.
Date: 1948
Creator: Ashenburg, Norman J.; Rothermel, J. F.; Baxter, Robert; Eriksen, Nils; Cobler, John G. & Harrison, William N.
Partner: UNT Libraries Government Documents Department

The Toxicity of Fluorine

Description: The following report discusses the toxicity of fluorine as described in literature on fluorine intoxication and case studies of Roholm's experimental observations.
Date: 1943
Creator: Ferry, J. L.
Partner: UNT Libraries Government Documents Department

Cytotoxicity and Functional Toxicity of Mefloquine and the Search for Protective Compounds

Description: Mefloquine hydrochloride is an antimalarial agent that has been used for the past 40 years. Numerous reports of neurological side effects have recently led the FDA to issue a strong warning regarding long-term neurological effects. This warning lead to the U.S. Army’s Special Forces and other components to discontinue its use in July of 2013. Despite reported adverse side effects, mefloquine remains in circulation and is recommended to travelers going to specific Asian countries. Mefloquine has been used as a treatment for those already infected with the malaria parasite (blood concentrations ranging from 2.1 to 23 µM), and as prophylaxis (blood concentrations averaging 3.8 µM) (Dow 2003). The purpose of this study was to quantify Mefloquine’s toxicity using spontaneously active nerve cell networks growing on microelectrode arrays in vitro and to identify compounds that alleviate or reduce toxic effects. The current literature on mefloquine toxicity is lacking electrophysiological data. These data will contribute to research on the mechanism of adverse side effects associated with mefloquine use. Sequential titration experiments were performed by adding increasing concentrations of mefloquine solution to cultured neurons. Network responses were quantified and reversibility was examined. In each network, activity decreases were normalized as a percent of reference activity yielding a mean IC50 value of 5.97 ± 0.44 (SD) µM (n=6). After total activity loss, no activity was recovered with two successive medium changes. To test for network response desensitization resulting from sequential applications over 5-6 hr periods, one-point titrations at varying concentrations were conducted with fresh networks. These experiments yielded a single concentration response curve with an IC50 value of 2.97 µM. This represents a statistically significant shift (p < 0.0001) to lower concentrations of mefloquine, demonstrating that sequential applications result in network desensitization. After mefloquine exposures, cells were evaluated for irreversible cytotoxic damage. Over a ...
Date: May 2015
Creator: Holmes, Katelyn
Partner: UNT Libraries

Toxicological assessment studies of the in vitro and in vivo effects of methyl 2-chloro-2-propenoate [methyl (α)-chloroacrylate]

Description: the toxic effects resulting from acrylic monomer exposure can pose as occupational risk factors for those involved in the manufacture, distribution, and use of the monomer and as potential risk factors for those accidentally exposed. This study is a toxicological assessment of the in vivo (intact animal) and in vitro (isolated human cell culture) responses to acute methyl (α)-chloroacrylate (MCA) exposure.
Date: August 1984
Creator: McClure, Fred Leland
Partner: UNT Libraries

Two Year Feeding Test

Description: The following report presents the results of the second year of the two-year feeding tests of uranium compounds to 50 male and 50 female rats.
Date: 1949
Creator: Maynard, Elliott A.; Downs, William L. & Hodge, Harold C.
Partner: UNT Libraries Government Documents Department

The Performance of Silicon Based Sensor and its Application in Silver Toxicity Studies

Description: The silicon based sensor is able to detect part per trillion ionic silver in 0.0098% hydrofluoric acid based on the open circuit potential (OCP) measurement. The OCP jump of 100 ppt ionic silver solution is up to 120 mV. The complex agent can effectively suppress the ionic silver concentration and suppress the OCP signal. The ability of complex agent to suppress the OCP signal depends on the formation constant of the complex with silver. The complex adsorbed on the sensor surface induces a second OCP jump, the height of the second jump depends on the formation constant of the complex. The MINEQL chemical equilibrium modeling program is used to calculate the ionic silver concentration when complex agent presents, a discrepancy is found between the MINEQL simulation result and the OCP signal of the silicon based sensor. The toxicity of ionic silver to C. dubia is studied parallel to the OCP signal of silicon based sensor. Less toxicity is found when the complex agent is present similar to the OCP signal. Another discrepancy is found between the MINEQL simulation and the toxicity test when MINEQL simulation is used to predict and control the ionic silver concentration. The data from both biosensor C. dubia and silicon based sensor support each other and both are not in agreement with MINEQL simulation prediction.
Date: August 2000
Creator: Peng, Haiqing
Partner: UNT Libraries

Respirable Crystalline Silica in the Workplace: New Occupational Safety and Health Administration (OSHA) Standards

Description: This report discusses the Occupational Safety and Health Administration's (OSHA) newly published new standards regulating exposure to crystalline silica in the workplace. Under the new standards, the Permissible Exposure Limit (PEL) for crystalline silica will be reduced to 50 µg/m3 (micrograms per cubic meter of air). Employers will be required to monitor crystalline silica exposure if workplace levels may exceed 25 µg/m3 for at least 30 days in a year and provide medical monitoring to employees in those workplaces. In the case of construction workers, medical monitoring is required only if the new standards require workers to wear respirators for at least 30 days in a year.
Date: May 31, 2017
Creator: Szymendara, Scott D.
Partner: UNT Libraries Government Documents Department