Toxic Chlorinated Hydrocarbons Research Articles

Veterinary utility of dried blood spots for analysis of toxic chlorinated hydrocarbons

Dried blood spots (DBS) on filter paper provide a simple and convenient means of collecting, storing and shipping samples for veterinary diagnostics related to toxin exposures. This paper presents validation data on analysis of DBS for chlorinated persistent organic pollutants, specifically 4,4′-dichloro-diphenyl-trichloroethane (4,4′-DDT) and its breakdown product 4,4′-dichlorodiphenyl-dichloroethylene (4,4′-DDE), lindane and a representative polychlorinated biphenyl (PCB) congener PCB-153. Analysis was by gas chromatography with electron capture detection (GC-ECD). The method required one 12.5 mm diameter spot representing application of 50 μL of blood, and working limits of detection (LOD) for each of the compounds was 5 ppb. Data are presented on development and description of the method, assay precision, LOD and quantitation, linearity, accuracy, specificity, effects of long-term storage and ruggedness. The method was also applied to 27 avian DBS, and 4,4′-DDE was detected in the majority of samples.

Accelerated Solvent Extraction Improves Efficiency of Lipid Removal from Dry Pet Food While Limiting Lipid Oxidation

AbstractAccelerated solvent extraction (ASE) was evaluated for extracting lipids from baked and extruded dry pet foods to determine factors controlling extraction efficiency and effects on lipid oxidation. Hydroperoxide decomposition and new lipid oxidation were minimal at 40 °C but increased at higher extraction temperatures without increasing yields. Maximum extraction required grinding samples to 250 µm particles, presence of polar solvents [chloroform, chloroform/methanol 2:1 (v/v) mixed, hexane/methanol 2:1 (v/v)], and a minimum of 20 min total static extraction time in repeat extraction cycles. Hexane and methanol injected into extraction cells simultaneously but separately was able to nearly duplicate extractions of chloroform/methanol, providing an option for replacing toxic chlorinated hydrocarbon solvents in ASE. However, lipid oxidation was higher in hexane. Yields were quantitative in baked biscuits but lower in extruded kibbles due to more dense, complex molecular structures. ASE extraction yields of 40 min or less were comparable to manual extraction yields of 24–48 h, with lower oxidation. Overall, one or two ASE extraction cycles with static times less than 20 min appeared to provide adequate lipid yields that accurately reflect lipid composition while inducing minimal modification when lipid oxidation products are the analytical endpoint.

Trichloroethylene, tetrachloroethylene and carbon tetrachloride in an urban atmosphere: mixing ratios and temporal patterns

The measurement of halogenated hydrocarbons in the atmosphere is a matter of great interest owing to their adverse effects on the human health and the environment. This work is focused on the measurement of three toxic chlorinated hydrocarbons: trichloroethylene (TCE), tetrachloroethylene (PCE), and carbon tetrachloride (CTC). Moreover, CTC is a greenhouse gas and an ozone depleting gas, restricted under the Montreal Protocol. Owing to their low reactivity, the target chlorinated hydrocarbons are considered to be persistent and, thus, many measurements only address their mean mixing ratios (a concentration measure expressed as mol/mol). Consequently, most of the reported data have low temporal resolution as daily, seasonal or yearly mean mixing ratios, obtained with few measurements. In the study reported in this paper hourly measurements were performed for a long period of time: almost two years for TCE and PCE, and one year for CTC. The main objective was to study the temporal variability of the chlorinated hydrocarbons with high temporal resolution in order to identify their main sources and to enhance the understanding of their atmospheric processes. During the measurement period, March 2007–February 2008 with N = 3290 valid data, CTC showed a mean mixing ratio of 0.16 ppbv (SD = 0.13) with lower temporal variability than the majority of non-methane hydrocarbons (NMHCs), being very well mixed in the urban atmosphere owing to its long lifetime. TCE and PCE mean mixing ratios for the May 2006–February 2008 period, were 0.13 ppbv (SD = 0.42, N = 4601) and 0.25 ppbv (SD = 0.54, N = 4709) respectively, with a larger temporal variability. The study of the sources of TCE and PCE reveals that both compounds have industrial and/or commercial origin, but with different main sources.

Catalytic dechlorination of polychlorinated biphenyls in subcritical water by Ni/Fe nanoparticles

The present study was carried out to better understand the reactivity of nanoscale Ni/Fe particles towards the dechlorination of polychlorinated biphenyls (PCBs) contained in waste capacitor oil and the corresponding dechlorination mechanism in subcritical water. Batch experiments showed that nanoscale Ni/Fe particles could more quickly and effectively dechlorinate PCBs stepwise as compared to nanoscale zerovalent iron (n-ZVI) and nano-Ni 0. The dechlorination products were much more centralized in the presence of Ni/Fe than other particles, and biphenyl, cyclohexyl-benzene and 1-alkyl-benzenes were the main products which can be used as raw chemicals. Moreover, catalytic hydrogenation by virtue of introduction of Ni 0 as catalyst can not only result in rapid dechlorination but also avoid formation of toxic chlorinated hydrocarbons. The reactivity of nanoscale Ni/Fe can retain in subcritical water for rapid catalytic hydrodechlorination. This process poses the prospect of recovery of valuable chemicals in the course of disposal of hazardous PCB-containing capacitor oil or transformer oil.

Inhibition of PCDD/F and PCB formation in co-combustion

Co-combustion of coal-solid waste mixtures in pilot and laboratory-scale combustors with emphasis on monitoring of toxic chlorinated hydrocarbon emissions such as polychlorinated dibenzo- p-dioxins and -furans (PCDD/F) and polychlorinated biphenyls (PCB) is elaborated. The objective of the work is to investigate the so-called primary measures technique. Twenty different thermally resistant inorganic compounds were added directly to the fuel as inhibitors of PCDD/F formation. The fuel-types used in this study included lignite coal, pre-treated municipal solid waste and polyvinyl chloride (PVC). Principle component analysis (PCA) provides the basis for a feasible discussion about the efficiency of 20 inhibitors on PCDD/F and PCB formation. The study showed that the metal oxides group investigated had no inhibitory effect. Although the single N- and S-containing compounds, used as additives for the type of lignite coal, solid waste and PVC fuel, are not very effective as inhibitors, all other N- and S-containing substances are capable to strongly reduce PCDD/F and PCB flue gas emission. The most effective inhibitors are (NH 4) 2SO 4 and (NH 4) 2S 2O 3. (NH 4) 2SO 4 present at 3% of the fuel can reduce the PCDD/F emissions to 90%. Its low cost and high efficiency favour them as useful for full-scale combustion units.

Development of Recycling Technologies, and Functional Material Formation by Hydrothermal Processes

In order to establish a sustainable society, with practical material recycling, it is appropriate to focus on a range of guiding ``Earth principles,'' including the character and application of hydrothermal processes. In this paper, it is demonstrated how information obtained from the study of fundamental Earth principles can be used to inspire the development of new methods for material recycling, such as the following: 1) Hydrothermal hot-pressing processes, simulating the formation of sedimentary rock sequences, can be used for the solidification of toxic and hazardous materials. 2) Organic materials could be formed from CO2 under hydrothermal conditions (using Fe and Ni metals, and low valence Fe oxides), at temperature and pressure conditions consistent with a subduction (tectonic) setting, such as (under Japan) where the Pacific Plate sinks beneath the (Eurasian) continental plate. 3) Diamond-structured carbon may be formed from toxic chlorinated hydrocarbon, in very high pressure regions of the Earth, and at high alkaline hydrothermal conditions, where magma formation may occur. 4) High temperature dry steam in rock fractures (at near critical conditions -i.e. below saturated vapor pressure, but relatively high pressure) is not only a source/carrier of noble metals, including gold, silver and copper, but also ceramic materials, silica and alumina. Its laboratory simulation may also be a guide for the formation of thin layer silicate ceramics on metal plates (e.g. SUS-304 nickel alloy). 5) To design an underground boiler in hot dry rock, non-equilibrium dissolution and deposition hydrothermal processes may be studied using a tube reactor, which simulates fluid flow and temperature gradients in fractured hot rock.

Toxic chlorinated and polyaromatic hydrocarbons in simulated house fires

Toxic chlorinated hydrocarbons (polychlorinated biphenyls, benzenes and dioxins and furans) and polyaromatic hydrocarbons were examined in combustion gas and deposited soot wipe samples from simulated house fires. Concentrations of these substances were high during the fires, the amounts of polychlorinated dioxins and furans (PCDD/Fs) in the combustion gas varying from 1.0 to >7.2 ng/m 3 (I-TEQ) and those of polyaromatic hydrocarbons from 6.4 to 470 mg/m 3. Thus large amounts of organic compounds may be released in house fires. As a result, there is a need for careful personal protection of fire-fighters and remediation workers against combustion gases during a fire and on contaminated surfaces after it.

Electrochemical Continuous Decomposition of Chloroform and Other Volatile Chlorinated Hydrocarbons in Water Using a Column Type Metal Impregnated Carbon Fiber Electrode

Trihalomethane and other chlorinated hydrocarbons are known to be toxic to human health. However, removal of these compounds from water is not easy. We attempted continuous electrochemical decomposition of chloroform that is the main compound of trihalomethanes and some toxic chlorinated hydrocarbons in water using a metal-impregnated carbon fiber electrode (CFE). At Ag- and Zn-impregnated CFE, concentration of chloroform in 0.5 M K2SO4 (the supporting electrolyte) solution was decreased from 0.25 m mol/L to below the limit of detection of our analysis system (1 ppm) at a flow rate of 1 mL/min. The main product of electrolysis was methane. This high efficiency, determined by the chemical yield, hardly changed at a flow rate of 20 mL/min at a Ag-impregnated CFE. At a flow rate of 1 mL/min, chloroform was degraded with a decomposition efficiency of almost 100% even in the solution without the supporting electrolyte, whereas at a higher flow rate, the efficiency for the decomposition of chloroform decreased with a decrease in the concentration of the supporting electrolyte. Tetrachloroethylene, 1,1,1-trichloroethane, and 1,1,2-trichloroethane were also decomposed at a Ag-impregnated CFE with an efficiency of almost 100%.

Low Volatile Chlorinated Hydrocarbons and Heavy Metals in Aquatic Sediments in Berlin and Environs

Abstract Chlorinated hydrocarbons of low volatility, especially DDT, HCH, and PCB, have been used as indicators of the level of pollution in aquatic sediments. These compounds are present in all the sediment samples analysed by gas chromatography. Enrichment factors between water and sediment are high (Kd = 85,108 in the case of DDT), documenting the strong geoaccumulation tendency of toxic chlorinated hydrocarbons. No linear relationship was observed between the concentration of contaminants (HCH and PCB) and the amount of organic matter in the sediments. The application of the EVOLON model to determine the kinetics of sorption showed clearly a value of saturation. The sorbed amount of these chlorinated hydrocarbons appears to be largely dependent upon that portion of organic matter which is on the surface of the sediment particles. From the metals investigated Hg, Pb, Cu, Cd and Zn are of anthropogenic origin; Cr, Ni and Co are of geochemical origin and correspond to background values.

Catalytic destruction of chlorofluorocarbons and toxic chlorinated hydrocarbons

The problem of the destruction of the ozone layer by chlorofluorocarbons (CFCs) has led to the proposed phase-out of their production by 1995. A number of chlorinated hydrocarbons which are toxic to man have also been found to destroy the ozone layer. A series of catalysts were tested for their ability to destroy CFC113 and trichloroethylene. CFC113 destruction over alumina-based catalysts led to severe catalyst deactivation due to fluorination of the alumina. However, zirconia-based catalysts were found to have some tolerance against fluorine species. A Pt/ZrO 2-(PO 4) catalyst was developed which could maintain more than 99% conversion of CFC113 over a 300 hour trial period at 500°C. The major product was CO 2 with a yield above 93%. A significant side reaction (selectivity 5%) was observed due to the fluorination of incoming CFC113 feed to form CFC114. A reaction mechanism was hypothesized for CFC113 destruction over zirconia-based catalysts. Trichloroethylene destruction was more easily achieved than CFC113. Over Pt/ZrO 2, more than 99.9% conversion was possible at 500°C over a 100 hour trial period. A side reaction associated with the chlorination of the feed to tetrachloroethylene had a selectivity below 0.05% indicating that the reactivity of the fluorine species was far higher than the chlorine species.

Low volatile chlorinated hydrocarbons in aquatic sediments in Berlin and surrounding areas

AbstractLow volatile chlorinated hydrocarbons, especially DDT and HCH, have been used as indicators of the level of pollution in aquatic sediments. These compounds were present in all the sediment samples analysed in this study by gas chromatography. Enrichment factors between the water and sediment were high (Kd = 85‐108 for DDT), documenting the strong geoaccumulation of toxic chlorinated hydrocarbons. in contrast with the generally held view, no linear relationship was observed between the concentration of HCH and PCBs and the organic matter content of the sediment. the application of the EVOLON model to determine the kinetics of sorption clearly showed a saturation value. the sorbed amount of low volatile chlorinated hydrocarbons depends to a large extent on the amount of organic matter on the surface of the sediment particles.

Kinetics of Methane-Oxidizing Biofilms for Degradation of Toxic Organics

The kinetics of methane-oxidizing bioreactors for the degradation of toxic organics are modeled. Calculations of the fluxes of methane and toxic chlorinated hydrocarbons were made using a biofilm model. The model simulated the effects of competition by toxics and mediane on their enzymatic oxidation by the methane monooxygenase. Dual-competitive-substrate/diffusion kinetics were used to model biofilm co-metabolism, integrating equations of the following form:where S1 and S2 are the local concentrations of methane and toxic compound, respectively, and r and K are the maximum uptake rates and Monod coefficients, and x is the distance into the biofilm.

The successful use of “high level” PEEP in near fatal Endrin poisoning

The insecticide Endrin is a highly toxic chlorinated hydrocarbon which can cause severe CNS and respiratory derangement. Death usually follows intoxication within 24 hours. A 19-year-old male developed convulsions and gross pulmonary edema after the ingestion of Endrin. His trachea was intubated and constant positive pressure ventilation with PEEP of up to 28 cm H2O was instituted. The patient survived and recovery appeared to be complete. Severe pulmonary edema is not a common finding in patients who have Endrin poisoning. The use of PEEP above 15 cm H2O is a controversial issue; however, we believe that it contributed significantly to the survival of our patient.

Toxicities of Several Pesticides to Two Species of Cladocerans

Abstract Laboratory bioassays were conducted with some chlorinated hydrocarbon insecticides, organophosphate insecticides, other insecticides and acaricides, and with herbicides to determine their relative toxicities and immobilization values for two species of daphnids, Daphnia pulex and Simocephalus serrulatus. Both species are satisfactory bioassay organisms for the determination of a wide variety of pesticides, with D. pulex being the more sensitive. The organophosphate insecticides were generally more toxic than the chlorinated hydrocarbons to both species. DDVP was the most toxic compound investigated. DDT was the most toxic chlorinated hydrocarbon tested, and lindane the least. There was a wide range in the toxicity of hydrocarbons to D. pulex, with 48-hour EC50 values ranging from 0.36 to 460 ppb. DDT was 2.9 times more toxic at 50 F than at 80 F. Malathion was 8.8 times more toxic at 50 F than at 70 F to S. serrulatus. Endrin was 12 times more toxic than dieldrin to D. pulex. DDT was 2.6 times mo...