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PubMedDate not supplied

Volatile organic compounds and building bake-out.

VOCs are generally present in indoor air at concentrations greater than, and not infrequently much greater than, those of outdoor air. These VOCs cover a broad spectrum of compounds, ranging from about 20 to several hundred in any given sample of indoor air. However, the concentrations observed in nonindustrial indoor air samples are generally much lower than occupational health standards. Still, the sources of VOCs indoors are varied and ubiquitous, and the health effects of exposure to VOC are varied and range from irritant effects associated with SBS, to carcinogenic and reproductive effects. A recent study of the health effects of exposure to low concentrations of VOCs has produced surprising results and insight into some of the more subtle health effects. However, additional study is needed to confirm these effects. Many general techniques for mitigating exposures to VOCs are available; the difficulty lies in obtaining the specific information necessary to apply these techniques effectively to a given problem. In some cases this information relates to diagnostics, either to the cause of particular symptoms in individuals or about the particular source or sources of VOCs. In other cases, this information is related to the application and efficacy of a particular mitigation technique for a particular problem. Bake-out is a promising technique for reducing exposures to VOCs in new office buildings. However, further effort in delineating its utility is necessary before it can be recommended.

Air Pollutants, Occupational↗
PubMedDate not supplied

Inter-individual variability in blood/air partitioning of volatile organic compounds and correlation with blood chemistry.

In vitro blood/air partition coefficients (KB/A) for acetone, 1,1,1-trichloroethane, toluene, and styrene were measured in blood samples from 73 human subjects and correlated with blood chemistry parameters (hematocrit, total cholesterol, serum triglycerides, serum albumin, total plasma proteins, Na+, K+, Cl-, and HCO3-). Statistically significant inter-individual variation existed in KB/A between some subjects. Substitution of group or generic in vitro KB/A values for values determined in some individuals could introduce errors of up to 50%. However, most subjects could be well represented by group averages (mean +/- SD; acetone, 301 +/- 22; 1,1,1-trichloroethane, 6.0 +/- 0.8; toluene, 19 +/- 3; styrene, 62 +/- 10). The KB/A values for acetone, 1,1,1-trichloroethane and toluene were normally distributed. The data for styrene appeared to deviate from a normal distribution and may have been bimodal. The KB/A values for the two structurally related compounds, toluene and styrene, were strongly correlated within individuals, while the KB/A values for compounds with less structural similarity, such as acetone and styrene, were poorly correlated. At most, 15% of the variation in KB/A among individuals could be explained by variation in the measured blood chemistry parameters. When the entire sample group was considered, blood chemistry parameters were not significantly correlated with KB/A for any compound. The KB/A of 1,1,1-trichloroethane was significantly correlated with the concentration of cholesterol and triglycerides in females. Sex was a significant grouping variable for the correlation of albumin concentration with the KB/A of styrene. Age was not a significant correlation variable. Blood chemistry parameters which previously have been correlated with KB/A in small sample groups do not appear to be significantly correlated in our larger sample group.

Acetone↗
PubMed1998

[Exposure of the population to volatile organic compounds inside an automobile and a subway train].

Air quality, in particular in urban regions, is affected by the emissions of the traffic and meanwhile for some substances motor vehicles became the dominating source. For valid quantitative risk assessment of the general population it is necessary to have informations about the main routes of exposure. Therefore in a pilot study 1994 and two times in summer 1995 and winter 1996 aromatic hydrocarbons, carbon monoxide (CO) and carbon dioxide (CO2) were determined under different meteorologic conditions inside of a car (a two year old VW-Golf with a three-way catalyst) and in a subway-train. The car route followed the subway (31 km underground) and crossed the central parts of Berlin in streets with high traffic density. The mean values for benzene obtained during the three measurement periods inside the car were 21.1/21.5 and 21.6 micrograms/m3 (daily maximum: 31.9/26.3 and 35.0 micrograms/m3) and inside the subway 8.4/5.4 and 7.4 micrograms/m3 (daily maximum: 16.0/7.4 and 10.3 micrograms/m3). The mean levels of CO in the car were 6 ppm (summer) and 5 ppm (winter) respectively, with peak concentrations of 33 and 70 ppm (10-minutes maximum). In the subway the values were 2 ppm (summer and winter); (10-minutes maximum: 5 and 12 ppm). A comparison between the two types of traffic shows three times higher concentrations of benzene inside the car. Our results demonstrate that the exposure of car occupants to benzene has to be taken into account for risk assessment. The concentration of CO inside the car is three to four times higher than in the subway train. Compared with other studies we found only low concentrations of CO inside the car.

Air Pollution, Indoor↗
PubMed2005

Chemical water quality in Thailand and its impacts on the drinking water production in Thailand.

In Thailand, surface water and groundwater are the main water sources for tap water and drinking water production. Thirty-six different samples from surface waters from Chao Praya and Mae Klong rivers, tap waters, bottled drinking waters, groundwaters and commercial ice cubes from around the Bangkok area were collected. Water samples were also taken from two waterworks in the Chonburi province. The extensive survey showed that, overall in all water samples investigated, there was only a minor pollution which could be traced back to the analyses performed including amongst others total organic carbon, inorganics and heavy metals, pesticides, organochlorine compounds, volatile organic compounds, surfactants, pharmaceuticals and disinfection by-products. However, whenever organic micropollutants could be detected in surface water, such as, e.g. the herbicide atrazine, they were also present in the tap water produced thereof proving that the present treatment steps are not sufficient for removal of such pollutants. The concentration of disinfection by-products was higher in tap water produced from Chao Praya river than from Mae Klong river. Disinfection by-products were also found in bottled drinking water. Commercial ice cubes contained anionic surfactants and their metabolites at elevated concentrations. The data of this study constitute the first set of homogenous data for the chemical water quality and also aid development of new water quality criteria in Thailand.

Data Collection↗
PubMed2001

Molecular structure-based prediction of human abdominal skin permeability coefficients for several organic compounds.

Mechanistically based predictions of skin permeability coefficients (Kp) derived solely on the basis of molecular structure information of organic compounds have not been reported previously. The objective of the present study was to predict the human abdominal Kp of structurally unrelated organic compounds using a mechanistic equation that takes into account compound-specific and species-specific determinants of Kp and relates the compound-specific determinants directly to molecular structure information. The method consisted of obtaining predictions based on a modified form of the conventional equation used to describe Kp (= P x D/L, where P, D, and L represent the stratum corneum:water partition coefficient, diffusion coefficient, and path length of diffusion). The value of P was predicted from the n-octanol:water partition coefficient (Po:w) computed from molecular structure information as well as the lipid, protein, and water contents in stratum corneum. The value of D was predicted according to the conventional Einstein-Stoke equation using the molar volume (Vmolar) of compounds computed from molecular structure information as well as data on viscosity of the stratum corneum components. Finally, the value of L was estimated in accordance with the characteristics of the diffusion pathways in the stratum corneum (i.e., transcellular and intercellular pathways). The average ratio of predicted Kp to the corresponding mean experimental values obtained from the literature was 1.25 (SD = 0.68, r = .95) for 47 structurally unrelated organic compounds (volatile organics and drugs), which were characterized by the presence of less than 2 hydrogen bonding groups and Vmolar < 231 cm3/mol. The present study is the first initiative that permits prediction of the human Kp of organic compounds by using molecular structure information as the sole chemical-specific input in a mechanistic equation.

Abdomen↗
PubMed2002

Microbial cycling of volatile organic sulfur compounds.

Microbial cycling of volatile organic sulfur compounds (VOSCs), especially dimethyl sulfide (DMS) and methanethiol (MT), is intensively studied because these compounds play an important role in the processes of global warming, acid precipitation, and the global sulfur cycle. VOSC concentrations in freshwater sediments are low due to the balance between the formation and degradation of these compounds. These reactions occur for the greater part at the oxic/anoxic interphase of sediment and water column. In contrast to marine ecosystems, where dimethylsulfoniopropionate is the main precursor of MT and DMS, in freshwater ecosystems, VOSCs are formed mainly by methylation of sulfide and to a lesser extent from the degradation of S-containing amino acids. One of the major routes for DMS and MT formation through sulfide methylation is anaerobic O-demethylation of methoxylated aromatic compounds. Inhibition studies have revealed that the major part of the endogenously produced MT and DMS is degraded anaerobically by methanogens. The major bacterial groups involved in formation and consumption of VOSCs are described.

Bacteria↗
PubMed2004

Volatile substance abuse--post-mortem diagnosis.

A substantial number of children and adolescents world-wide abuse volatile substances with the intention to experience an euphoric state of consciousness. Although the ratio of deaths to nonfatal inhalation escapades is low, it is an important and preventable cause of death in young people. In the analytical investigation of volatile substances proper sample collection, storage and handling are important in view of the volatile nature of the compounds. Volatile organic compounds in post-mortem matrices such as blood, urine and tissues are generally determined by gas chromatography after extracting the compounds with methods such as static and dynamic headspace or even with pulse-heating and solvent extraction. In post-mortem cases, metabolites in urine seem less relevant, however, trichloroethanol and trichloroacetic acid were determined in several cases. When interpreting qualitative and quantitative results, researchers should be aware of false conclusions. The main reason why scepticism is necessary is the occurrence of losses of analytes during sampling, sample handling and storage, which results in false quantitation.

Administration, Inhalation↗
PubMed2001

Global tropospheric ozone dynamics. Part I: Tropospheric ozone precursors.

An overview of the tropospheric ozone changes is presented focussing mainly on the tropospheric ozone precursors. The complexity of the problem is shown through the consideration of a great number of relevant substances, like nitrogen compounds, volatile organic compounds, peroxyacetyl nitrate, hydroxyl radical, carbon monoxide, alkyl nitrates. The up-to-date knowledge on the relevant numerical modelling is presented in Part II.

Atmosphere↗
PubMedDate not supplied

[Indoor air quality in an Italian military submarine].

In recent years there has been increasing interest on studies concerning indoor air quality and focusing on risk factors for exposed subjects. Particularly, airborne chemicals, whose adverse effects are well known, have been identified and determined in means of transport as in other indoor places. As concerns chemical air concentrations in submarines, only a limited number of studies have been published. This paper reports measured concentration data for organic compounds (total volatile organic compounds, substances with a chemical bond S-O, nitrogen compounds, carbon monoxide, carbon dioxide, and different organic solvents) in the air sampled during an 8-h period in an Italian Military submarine, under routine operations. We observed that a periodicalfresh-air intake operation (snorkel) might cause temporary increase of contaminants levels in indoor air. Moreover, we could find that pollutants sometimes reach notable peak concentrations being potentially able to induce adverse health effects in crewmembers. Our data highlight the need to promote further investigations.

Air Pollutants↗
PubMed2006

Volatile organic sulfur compounds in a stratified lake.

Three volatile organic sulfur compounds (VOSCs), dimethyl sulfide (DMS), carbon disulfide (CS(2)), and dimethyl disulfide (DMDS), were detected in the stratified water column of a lake (Linsley Pond) in Connecticut. The compounds DMS and DMDS appeared in both the oxic and the anoxic portions of the water column, CS(2) was primarily found in anoxic hypolimnion. Algal metabolism and/or bacterial degradation of sulfur-containing amino acids or other organic materials are potential sources of VOSCs in the oxic lake water. Reactions of hydrogen sulfide with organic compounds and microbial degradation of organic matter may be responsible for the production of VOSCs in the anoxic lake water. The vertical distribution patterns of these three VOSCs varied from month to month in the summer, but the daily profiles obtained in one 5-day period in the summer displayed consistency. No clear diurnal pattern for any of the three VOSCs was observed. Based on observation that these VOSCs were not present in surface and near surface waters of Linsley Pond, freshwater inputs of reduced sulfur compounds to the atmosphere may be insignificant.

Carbon Disulfide↗
PubMed1998

Abatement of volatile organic sulfur compounds in odorous emissions from the bio-industry.

Compounds of interest in this work are methanethiol (MeSH), dimethyl sulfide (Me2S), dimethyl polysulfides (Me2Sx) and carbon disulfide (CS2) since these volatiles have been identified as predominant odorants in the emission of a wide range of activities in the bio-industry (e.g. aerobic waste water treatment plants, composting plants, rendering plants). In these processes, the occurrence of volatile organic sulfur compounds is mainly related to the presence of anaerobic microsites with consecutive fermentation of sulfur containing organic material and/or to the breakdown of the latter due to thermal heating. Due to the chemical complexity of these low-concentrated waste gas streams and the high flow rates to be handled, mainly biotechnological techniques and scrubbers can be used to control the odour emission. When using biofilters or trickling filters, inoculation with specific microorganisms and pH-control strategies should be implemented to optimise the removal of volatile organic sulfur compounds. In scrubbers, chemical oxidation of the volatile organic sulfur compounds can be obtained by dosing hypochlorite, ozone or hydrogen peroxide to the scrubbing liquid. However, optimal operational conditions for each of these abatement techniques requires a further research in order to guarantee a long-term and efficient overall odour abatement.

Anaerobiosis↗