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PubMed2004

Novel aqueous foams for suppressing VOC emission.

Reducing volatile organic compound (VOC) emissions from crude oil/gasoline distribution and storage facilities is important in controlling environmental pollution and enhancing workplace safety. Stable aqueous foam formulations are developed to provide a mass transfer barrier to the emission of VOCs during loading of gasoline. Experiments are carried out in a bench-scale foam cell using liquid hexane as oil. The foam columns of 32 cm in height were able to suppress the plateau concentration of hexane vapors in the effluent by 87% under experimental conditions tested. Vapor suppression increased with foam height but was almost insensitive to liquid viscosity. These experiments are then upscaled from bench-scale to a vessel having an exposed surface area of roughly 2 orders of magnitude higher. Gasoline is used as oil in the upscaled experiments, and the concentrations of volatile hydrocarbons in the effluent are measured during oil loading. A 40-cm-thick foam column is found to reduce the emissions by 96% for foams prepared with deionized water and by 93.8% for foams prepared with 3.5 wt % NaCl brine for 10 h of oil loading.

Air Pollutants↗

PubMed2006

Potential role for gut microbiota in cell wall digestion and glucoside detoxification in Tenebrio molitor larvae.

Tenebrio molitor larvae were successfully reared free of cultivatable gut lumen bacteria, yeasts and fungi using two approaches; aseptic rearing from surface sterilized eggs and by feeding larvae with antibiotic-containing food. Insects were reared on a rich-nutrient complete diet or a nutrient-poor refractory diet. A comparison of digestive enzyme activities in germ free and conventional insects containing a gut microbiota did not reveal gross differences in enzymes that degrade cell walls from bacteria (lysozyme), fungi (chitinase and laminarinase) and plants (cellulase and licheninase). This suggested that microbial-derived enzymes are not an essential component of the digestive process in this insect. However, more detailed analysis of T. molitor midgut proteins using an electrophoretic separation approach showed that some digestive enzymes were absent and others were newly expressed in microbiota-free larvae. Larvae reared in antibiotic-containing refractory wheat bran diet performed poorly in comparison with controls. The addition of saligenin, the aglycone of the plant glucoside salicin, has more deleterious effects on microbiota-free larvae than on the conventionally reared larvae, suggesting a detoxifying role of midgut microbiota. Analysis of the volatile organic compounds released from the faecal pellets of the larvae shows key differences in the profiles from conventionally reared and aseptically reared larvae. Pentadecene is a semiochemical commonly found in other beetle species. Here we demonstrate the absence of pentadecene from aseptically reared larvae in contrast to its presence in conventionally reared larvae. The results are discussed in the light of the hypothesis that microbial products play subtle roles in the life of the insect, they are involved in the digestion of refractory food, detoxification of secondary plant compounds and modify the volatile profiles of the insect host.

Animals↗

PubMed2005

An experimental study to investigate the feasibility to classify paints according to neurotoxicological risks: occupational air requirement (OAR) and indoor use of alkyd paints.

The concept of occupational air requirement (OAR), representing the quantity of air required to dilute the vapor concentration in the work environment resulting from 1 l product to a concentration below the occupational exposure limit (OEL), was considered to have potential to discriminate between paints that can and cannot be used safely. The OAR is a simple algorithm with the concentration of volatile organic compound (VOC) in the paint, a discrete evaporation factor and the neurotoxicological effects-based OEL. Conceptually, OAR categories of paints for construction and maintenance applications could be identified that can be applied manually without exceeding OELs with no appreciable room ventilation. Five painters volunteered in an exposure study aimed at testing the OAR approach in practice. Total exposure to VOC was assessed in 30 experiments during the application of 0.5 l of paint in a defined 'standard indoor paint job'. Fifteen paints were prepared, reflecting differences in solvents (percentage, volatility, toxicity) with a range of OAR levels from 43 to 819 m(3)/l. Exposure was assessed by personal air sampling (PAS). In addition, real-time air monitoring was performed. All tests were conducted at minimum ventilation rate (< or=0.33 h(-1)). PAS results were expressed as percentage of the nominal OEL and ranged from 8 to 93% for high solids and from 38 to 168% for conventional paints. In general, higher VOC contents resulted in higher exposure. High volatile paints showed a statistically significant faster increase of VOC concentration with time compared with paints containing low volatile solvents. A significant relationship between OAR value and exposure was observed (R(2) = 0.73). The experiments indicate that OAR-based classification of paints predicts and discriminates risk levels for exposure to neurotoxic paint-solvents in indoor painting fairly well.

Air Pollutants, Occupational↗

PubMed2005

Investigation of MTBE and aromatic compound concentrations at a gas service station.

Methyl tert-butyl ether (MTBE) has been used as a fuel additive at levels of 2-11% in Taiwan for the past decade. The purpose of this additive is to enhance the octane, replace the use of lead-based anti-knock gasoline additives and reduce aromatic hydrocarbons. However, it is possible that oxygenated fuel has a potential health impact. To determine the air quality impact of MTBE, measurements were made of ambient MTBE and other gasoline constituents at a service station. Additionally, environmental conditions (wind speed, wind direction, and temperature, etc.) that could affect concentrations of emission constituents were measured. Gas samples were analyzed for target MTBE and volatile organic compounds, e.g., benzene and toluene. Ambient samples were collected using Tenax adsorbent tubes for mass spectrometric analysis at a service station located in Changhua County, Taiwan. The resulting measured ambient air concentrations were compared with Taiwan's regulatory standards for hazardous air pollutants. Subsequently, the factors controlling the formation of high-VOC levels at the service station and in the residential neighborhoods were identified. Additionally, the results can provide the Environmental Protection Agency (EPA) of Taiwan with useful information and prompt them to mandate this gas service station to install a refueling vapor recovery system.

Air Pollutants↗

PubMed2006

Volatile foraging kairomones in the littoral zone: attraction of an herbivorous freshwater gastropod to algal odors.

Volatile organic compounds (VOCs) produced by algae and cyanobacteria are primarily responsible for odors in fresh waters. Among other functions, VOCs may serve as important infochemicals in biofilms of benthic primary producers. VOCs liberated by benthic, mat-forming cyanobacteria can be used as habitat-finding cues by insects, nematodes, and possibly other organisms. We developed a new gastropod behavioral assay that allows detection of food preference without offering food, thus allowing the distinction between taste, which requires direct contact with the food source, and the detection of odorous infochemicals, which work over distance. We demonstrated that VOCs released from disintegrated cells of a benthic, mat-forming, green alga (Ulothrix fimbriata) are food-finding cues ("foraging kairomones") that attract the herbivorous freshwater snail Radix ovata. A mixture of three C5 lipoxygenase compounds and 2(E),4(E)-heptadienal that mimic the major VOCs released by U. fimbriata attracted the snails, whereas neither the mixture of C5 compounds nor 2(E),4(E)-heptadienal were effective when given alone. This study suggests that VOCs can play a steering role as infochemicals in freshwater benthic habitats, as has been established for many organismic interactions in terrestrial ecosystems.

Adsorption↗

PubMed2000

Analysis of residual solvents in pharmaceuticals with purge-and-membrane mass spectrometry.

A method using purge-and-membrane mass spectrometry (PAM-MS) was developed for the analysis of residual solvents in pharmaceutical products. The method combines dynamic headspace and membrane inlet mass spectrometry. The limits of detection for the compounds studied, benzene, toluene, chloroform, 2-pentene and 2-methyl- and 3-methylpentane, were 0.05-0.1 mg/kg. In quantitative analysis the method showed good linearity (r(2) > 0.998) and acceptable within-day (RSD = 7.9-18%) and between-day (RSD = 6.8-10%) repeatability. The PAM-MS method combined with the custom-made Solver program was compared with a method using purge-and-trap gas chromatography/mass spectrometry (P&T-GC/MS) for identification of residual solvents from authentic samples. The results showed that PAM-MS/Solver provides reliable identification of the main volatile organic compounds (VOCs) in the pharmaceuticals, but VOCs with low concentrations (below 0.5 mg/kg) were better identified by P&T-GC/MS. Other advantages of the PAM-MS method were short analysis times and non-requirement for pre-treatment of samples.

Alkenes↗

PubMed2000

Quantitative analysis of acetates in cigarette tobacco using solid-phase microextraction and gas chromatography-mass spectrometry.

A method incorporating solid-phase microextraction (SPME) and gas chromatography-mass spectrometry for the headspace analysis of selected volatile organic compounds present in cigarette tobacco is developed and evaluated. Quantitative information on methyl, ethyl, n-propyl, isopropyl, isopropenyl, vinyl, and butyl acetates present in 29 different flavor variants (full, light, and ultra-light) of the top ten selling brands in the United States is presented. The concentrations of the various acetate analytes range from the low nanaogram to microgram levels per cigarette. Clear differences are observed in the concentrations of various acetates when comparing the levels in brands from different manufacturers. The SPME technique provides a method that allows high sample throughput, requires little sample preparation, and yields useful analytical information. High precision is obtained on multiple measurements of cigarettes from an individual pack, but lower precision levels are observed in general when comparing results obtained on the analysis of cigarettes from different packs of the same brand. The higher pack-to-pack variations may be due in part to product aging with a proportionate amount of evaporative loss of the relatively volatile acetates.

Acetates↗

PubMed2005

Propylene glycol vapor contamination in controlled environment growth chambers: toxicity to corn and soybean plants.

A major, often unrecognized variable regulating plant growth in semi-closed environment is air contaminant. The vapor of propylene glycol (PG), which was used as coolant in growth chambers, has been found to be toxic to corn (Zea mays L.) and soybean (Glycine max L.) plants. PG solution leaked from a valve packing system and volatilized to vapor, which was trapped in a semi-closed growth chamber. Symptoms of leaf edge chlorosis, later developing into necrosis, were observed on the third day of emergence or on the third day after moving healthy plants into the chamber. For young soybean plants, symptoms were slightly different from those observed in corn plants; the chlorosis symptoms were not uniformly distributed on all leaves. Some soybean leaves curled up and others had white spots. This problem was identified by using a portable photoionization detector to obtain instantaneous readings of total volatile organic compound concentrations inside the chambers. The presence of PG in selected chambers was verified using sample collection with solid phase microextraction (SPME) followed by analysis with multi-dimensional gas chromatography mass spectrometry (MD-GC-MS). This information is pertinent to researchers who use controlled environment to grow plants.

Air Pollutants↗

PubMed2006

[Analysis of volatile constituents from leaves of plants by gas chromatography/mass spectrometry with solid-phase microextraction].

A method for analyzing volatile constituents from plant leaves with gas chromatography/mass spectrometry (GC/MS) coupled with solid-phase microextraction (SPME) was developed. The volatile compounds from the plant leaves inside a sealed flask maintained at 45 degrees C in a water bath were efficiently extracted with Polyacrylate (85 microm) SPME fibers prior to perform GC/MS analysis. The GC/MS analysis indicated that the volatile compounds from the plant leaves which is easy to be damaged by Tetraychus vienneis include relative large amounts of cis-3-hexenyl ester acetic acid, cis-3-hexenyl ester butanoic acid and alpha-famesene. These compounds were preliminarily confirmed to be accountable for attracting Tetraychus vienneis. This finding may lead to identify biological species for preventing and treating Tetraychus vienneis.

Clinical Laboratory Techniques↗

PubMed2005

Modeling MTBE and BTEX in lakes and reservoirs used for recreational boating.

It is generally recognized that the bulk of fuel-related volatile organic compounds (VOCs) in lakes and reservoirs come from motorized recreational boating, but a quantitative connection between the two has been difficult to establish. A detailed boating use survey was conducted at a Northern California multiple-use lake, and the results were used to quantify daily methyl tert-butyl ether (MTBE) and benzene, toluene, ethylbenzene, and xylene (BTEX) loading from recreational boating. A one-dimensional, process-based numerical model was used to predict VOC levels as a function of the number, type, and activity of marine engines using the lake, the vertical mixing dynamics of the lake, and the volatilization rates of the individual VOCs. The model was validated on two other reservoirs to establish its applicability under a range of climatic and boating conditions. The study further confirmed the link between motorized boating and surface-water VOC contamination. In addition, the results of this study suggest that volatilization alone is inadequate to describe the loss of volatile hydrocarbons from surface waters and that some combination of additional degradation processes is involved. Under low wind conditions, these degradation processes dominate the removal of MTBE. For toluene, these processes are always more dominant than volatilization. The mean relative percent difference (RPD) between measured and simulated VOC concentrations at the study site, accounting only for volatilization losses, was 50.6% for MTBE and 113% for toluene. A first-order submodel was implemented to account for losses other than volatilization, using decay coefficients estimated from the literature. The resulting mean RPDs between measured and modeled concentrations were 14.2% for MTBE and 4.5% for toluene.

Benzene↗

PubMed2006

Cleaning products and air fresheners: emissions and resulting concentrations of glycol ethers and terpenoids.

UNLABELLED: Experiments were conducted to quantify emissions and concentrations of glycol ethers and terpenoids from cleaning product and air freshener use in a 50-m3 room ventilated at approximately 0.5/h. Five cleaning products were applied full-strength (FS); three were additionally used in dilute solution. FS application of pine-oil cleaner (POC) yielded 1-h concentrations of 10-1300 microg/m3 for individual terpenoids, including alpha-terpinene (90-120), d-limonene (1000-1100), terpinolene (900-1300), and alpha-terpineol (260-700). One-hour concentrations of 2-butoxyethanol and/or d-limonene were 300-6000 microg/m3 after FS use of other products. During FS application including rinsing with sponge and wiping with towels, fractional emissions (mass volatilized/dispensed) of 2-butoxyethanol and d-limonene were 50-100% with towels retained, and approximately 25-50% when towels were removed after cleaning. Lower fractions (2-11%) resulted from dilute use. Fractional emissions of terpenes from FS use of POC were approximately 35-70% with towels retained, and 20-50% with towels removed. During floor cleaning with dilute solution of POC, 7-12% of dispensed terpenes were emitted. Terpene alcohols were emitted at lower fractions: 7-30% (FS, towels retained), 2-9% (FS, towels removed), and 2-5% (dilute). During air-freshener use, d-limonene, dihydromyrcenol, linalool, linalyl acetate, and beta-citronellol) were emitted at 35-180 mg/day over 3 days while air concentrations averaged 30-160 microg/m3. PRACTICAL IMPLICATIONS: While effective cleaning can improve the healthfulness of indoor environments, this work shows that use of some consumer cleaning agents can yield high levels of volatile organic compounds, including glycol ethers--which are regulated toxic air contaminants--and terpenes that can react with ozone to form a variety of secondary pollutants including formaldehyde and ultrafine particles. Persons involved in cleaning, especially those who clean occupationally or often, might encounter excessive exposures to these pollutants owing to cleaning product emissions. Mitigation options include screening of product ingredients and increased ventilation during and after cleaning. Certain practices, such as the use of some products in dilute solution vs. full-strength and the prompt removal of cleaning supplies from occupied spaces, can reduce emissions and exposures to 2-butoxyethanol and other volatile constituents. Also, it may be prudent to limit use of products containing ozone-reactive constituents when indoor ozone concentrations are elevated either because of high ambient ozone levels or because of the indoor use of ozone-generating equipment.

Air Pollutants↗

PubMed2003

Kinetics of benzene adsorption onto activated carbon.

An activated carbon bed adsorption process is influenced by the adsorbents' characteristics, volatile organic compound (VOC) characteristics, and process conditions. In the literatures, the adsorption processes of the adsorbents and VOCs were usually considered to be in equilibrium. In this study, the VOC adsorption processes by activated carbon were considered to be a kinetic process, i.e. they are not in equilibrium. Then, isothermal adsorption curves and a small column experiment were simulated.

Adsorption↗

PubMed2005

Relationship of Indoor, Outdoor and Personal Air (RIOPA) study: study design, methods and quality assurance/control results.

The Relationship of Indoor, Outdoor and Personal Air (RIOPA) Study was undertaken to evaluate the contribution of outdoor sources of air toxics, as defined in the 1990 Clean Air Act Amendments, to indoor concentrations and personal exposures. The concentrations of 18 volatile organic compounds (VOCs), 17 carbonyl compounds, and fine particulate matter mass (PM(2.5)) were measured using 48-h outdoor, indoor and personal air samples collected simultaneously. PM2.5 mass, as well as several component species (elemental carbon, organic carbon, polyaromatic hydrocarbons and elemental analysis) were also measured; only PM(2.5) mass is reported here. Questionnaires were administered to characterize homes, neighborhoods and personal activities that might affect exposures. The air exchange rate was also measured in each home. Homes in close proximity (<0.5 km) to sources of air toxics were preferentially (2:1) selected for sampling. Approximately 100 non-smoking households in each of Elizabeth, NJ, Houston, TX, and Los Angeles, CA were sampled (100, 105, and 105 respectively) with second visits performed at 84, 93, and 81 homes in each city, respectively. VOC samples were collected at all homes, carbonyls at 90% and PM(2.5) at 60% of the homes. Personal samples were collected from nonsmoking adults and a portion of children living in the target homes. This manuscript provides the RIOPA study design and quality control and assurance data. The results from the RIOPA study can potentially provide information on the influence of ambient sources on indoor air concentrations and exposure for many air toxics and will furnish an opportunity to evaluate exposure models for these compounds.

Air Movements↗

PubMed1999

Chamber assessment of formaldehyde and VOC emissions from wood-based panels.

Volatile organic emissions from particleboard, medium density fibreboard (MDF) and office furniture have been measured in dynamic environmental chambers, both small and room-sized. Characterisation of product emission properties in small chambers was possible when inter- and intra-sheet variations were considered. Formaldehyde emission factors for all products were approximately double European low-emission specifications and did not decay to the latter for several months. Long-term emission behaviour could not be predicted from short-term measurements. Volatile organic compounds (VOC) emissions were low for the MDF product, higher for particleboard, and highest for laminated office furniture. The compounds emitted differed from those reported in other countries. VOC emissions from the sheet products decreased more quickly than formaldehyde, reaching low levels within two weeks, except for MDF which was found to become a low-level source of hexanal after several months.

Air Pollution, Indoor↗

PubMed1999

Technology development in breath microanalysis for clinical diagnosis.

A new generation of breath tests detects trace amounts of endogenous volatile organic compounds (VOCs) present in the breath. The breath microanalysis is potentially fast and convenient. It opens up a new promising area of using the breath test as a noninvasive diagnostic tool for a variety of diseases. Recent developments in microanalysis technology are expected to greatly facilitate the use of the breath test in clinical evaluations and applications, and these developments are described in the present review.

Breath Tests↗

PubMed2005

[Chemical emission from water-based adhesives for flooring materials].

Emissions of 2-(2-butoxyethoxy) ethanol, 2-(2-butoxyethoxy) ethyl acetate, 2-fenoxyethanol, 2-ethylhexanol, alpha, beta pinene and total volatile organic compounds (TVOC) from water-borne adhesives for flooring materials were measured by means of emission test chamber 28 days (at 23 degrees C, 45% relative humidity, 0,5 air exchange/hour). For one adhesive the emission of 2 compounds was observed even after 28 days. TVOC emissions for one adhesive was very low. Some of adhesives may release of compounds which toxicity data have not been evaluated.

Adhesives↗

PubMed1999

[MVOC of fungi--use as an indicator for exposure level].

The production of microbial volatile organic compounds (MVOC) by fungi derived from biowaste was studied on synthetic agar (YES), compost-extract media (CEA VAR 1-3) and compost. Exposure assessment was carried out in composting facilities and the occurrence of VOC/MVOC was related to the presence of airborne fungi. A number of non-specific MVOC was found at all sampling sites or in each season, some of which showed preferences for certain sampling sites (3-methyl-1-butanol, 3-octanone). They seemed to be correlated with a certain species composition or with microbial activity, and may thus be used to describe a certain state of decomposition. Correlations between single volatiles and certain fungi were found in situ, but these findings did not match with the species-specific volatiles obtained from pure cultures.

Air Pollutants, Occupational↗

PubMed2003

Mutants of the nematode Caenorhabditis elegans that are defective specifically in their attraction to cycloheximide.

The nematode Caenorhabditis elegans exhibits chemotaxis toward a wide variety of chemicals including water-soluble molecules and volatile organic compounds. We have previously discovered that C. elegans wild-type strain N2 is strongly attracted by cycloheximide which has long been known as a bitter tastant for humans and other mammals. We describe here the isolation and initial characterization of the first mutants which were defective specifically in their attraction to cycloheximide. In our screenings, we selected two mutants that were defective in chemotaxis to cycloheximide but normal in their attraction to NH4Cl and histidine. These mutants also avoided quinine hydrochloride, CuSO4 and high concentrations of NaCl similar to the wild-type strain N2. Furthermore, no observable defect was detected in their attraction to volatile odorants such as isoamyl alcohol and diacetyl. Dye-filling experiments suggested that they have no morphological defect in the sensory endings of the amphid neurons.

Journal Article↗