Air to liver partition coefficients for volatile organic compounds and blood to liver partition coefficients for volatile organic compounds and drugs

Values of in vitro air to liver partition coefficients, K(liver), of VOCs have been collected from the literature. For 124 VOCs, application of the Abraham solvation equation to logK(liver) yielded a correlation equation with R(2)=0.927 and SD=0.26 log units. Combination of the logK(liver) values with logK(blood) values leads to in vitro blood to liver partition coefficients, as logP(liver) for VOCs; an Abraham solvation equation can correlate 125 such values with R(2)=0.583 and SD=0.23 log units. Values of in vivo logP(liver) for 85 drugs were collected, and were correlated with R(2)=0.522 and SD=0.42 log units. When the logP(liver) values for VOCs and drugs were combined, an Abraham solvation equation could correlate the 210 compounds with R(2)=0.544 and SD=0.32 log units. Division of the 210 compounds into a training set and a test set, each of 105 compounds, showed that the training equation could predict logP(liver) values with an average error of 0.05 and a standard deviation of 0.34 log units.     

Air to lung partition coefficients for volatile organic compounds and blood to lung partition coefficients for volatile organic compounds and drugs

Values of in vitro gas to lung partition coefficients, K(lung), of VOCs have been collected from the literature. For 44 VOCs, application of the Abraham solvation equation to log K(lung) yielded a correlation with R(2)=0.968 and S.D.=0.25 log units. Combination of the log K(lung) values with log K(blood) values leads to in vitro blood to lung partition coefficients, log P(lung) for 43 VOCs; an Abraham solvation equation correlated these values with a very poor R(2)=0.262 but with a very good S.D.=0.190 log units. Values of in vivo log P(lung) for 80 drugs were collected, and were correlated with R(2)=0.647 and S.D.=0.51 log units. When the log P(lung) values for VOCs and drugs were combined, an Abraham solvation equation could correlate the 123 compounds with R(2)=0.676 and S.D.=0.43 log units. Division of the 123 compounds into a training set and a test set, showed that the training equation could predict log P(lung) values with an average error of 0.001 and a standard deviation of 0.44 log units; for drugs in the combined test set the average error was 0.02 and the standard deviation 0.43 log units.     

Variability of environmental exposures to volatile organic compounds

Although studies of occupational exposure to volatile organic compounds (VOCs) often partition variability across groups, and between and within persons, those of environmental exposure to VOCs have not involved such partitioning. Using data from the Environmental Protection Agency's total exposure assessment methodology (TEAM) studies, we partitioned exposure variability across cities, and between and within persons for nine VOCs. The estimated variance components decreased in the order: within-person > between-person > across city. Despite their smaller magnitudes, estimates of between-person and across-city variance components were sufficiently large to provide reasonable contrast for informative epidemiology studies of most VOCs. Estimates of between-person variance components for environmental VOCs were similar to those published for occupational VOCs (groups defined by job and factory). However, estimates of within-person variance components were much greater for environmental VOCs, probably due to the greater diversity of locations (including the workplace) visited by the general public over time. For benzene and perchloroethylene, we used a simple model to calculate numbers of personal measurements required to relate the exposure level to health outcome statistically. About 10 times more personal measurements would be required to investigate perchloroethylene exposure as compared to benzene exposure; this disparity reflects the greater within-subject variability of perchloroethylene data compared to benzene data. We conclude that variability should be partitioned for environmental VOC exposures in much the same manner as for occupational exposures. There should be sufficient variability in the levels of most VOCs across cities and between subjects to provide reasonable contrast for informative epidemiology studies, as we illustrate for exposures to benzene. Yet, epidemiologists should be wary of investigating environmental VOCs without preliminary data with which to estimate the variance structure of exposure variables.     

Collection of a single alveolar exhaled breath for volatile organic compounds analysis

Measurement of specific organic compounds in exhaled breath has been used as an indicator of recent exposure to pollutants or as an indicator of the health of an individual. A typical application involves the collection of multiple breaths onto a sorbent cartridge or into an evacuated canister with the use of a relatively complex sampling apparatus. A new method has been developed wherein a single exhaled breath is directly transferred from the mouth into an evacuated 1 1 or 1.8 1 stainless steel SUMMA® canister. The single breath canister (SBC) method avoids the necessity for a complex sampling system requiring maintenance and cleaning and allows easy collection of samples. Additionally, it is possible to collect a rapid sequence of samples from a subject to establish the elimination curve subsequent to an exposure to specific volatile organic compounds with a theoretical resolution of adjacent breaths. The SBC method was compared to an accepted canister based sampling system to assure comparability and then used to demonstrate its utility by measuring the absorption and elimination of chloroform during and after exposure to chlorinated shower water. © 1995 Wiley-Liss, Inc.     

Blood concentrations of selected volatile organic compounds and neurobehavioral performance in a population-based sample

The authors analyzed data from a national sample to examine the relationships between blood concentrations of selected volatile organic compounds (VOCs) and the assessment scores of neurobehavioral evaluation tests. They calculated summary statistics to describe blood concentrations of 30 VOCs. For instance, the 95th percentiles were as follows: 1,1,1-trichloroethane, 0.799 microg/l; 1,4-dichlorobenzene, 11.081 microg/l; benzene, 0.476 microg/l; and toluene, 0.281 microg/l. For 1,4-dichlorobenzene, benzene, dibromochloromethane, and trichloroethene, a blood level higher than the 95th percentile was associated with a poorer neurobehavioral assessment score than was a blood level up to the 95th percentile. The authors found a linear relationship between blood toluene concentration and the Serial Digit Learning Test score. The findings suggest that exposure to certain VOCs may result in poor neurobehavioral performance. The study was exploratory and precludes a conclusive statement, so further investigation is warranted.     

Environmental exposure to volatile organic compounds among workers in Mexico City as assessed by personal monitors and blood concentrations.

Benzene, an important component in gasoline, is a widely distributed environmental contaminant that has been linked to known health effects in animals and humans, including leukemia. In Mexico City, environmental benzene levels, which may be elevated because of the heavy traffic and the poor emission control devices of older vehicles, may pose a health risk to the population. To assess the potential risk, portable passive monitors and blood concentrations were used to survey three different occupational groups in Mexico City. Passive monitors measured the personal exposure of 45 workers to benzene, ethylbenzene, toluene, o-xylene and m-/p-xylene during a work shift. Blood concentrations of the above volatile organic compounds (VOCs), methyl tert-butyl ether, and styrene were measured at the beginning and the end of a work shift. Passive monitors showed significantly higher (p > 0.0001) benzene exposure levels among service station attendants (median = 330 microg/m3; range 130-770) as compared to street vendors (median = 62 microg/m3; range 49-180) and office workers (median = 44 microg/m3, range 32-67). Baseline blood benzene levels (BBLs) for these groups were higher than those reported for similar populations from Western countries (median = 0.63 microg/L, n = 24 for service station attendants; median = 0.30 microg/L, n = 6 for street vendors; and median = 0.17 microgr;g/L, n = 7 for office workers). Nonsmoking office workers who were nonoccupationally exposed to VOCs had BBLs that were more than five times higher than those observed in a nonsmoking U.S. population. BBLs of participants did not increase during the work shift, suggesting that because the participants were chronically exposed to benzene, complex pharmacokinetic mechanisms were involved. Our results highlight the need for more complete studies to assess the potential benefits of setting environmental standards for benzene and other VOCs in Mexico.     

Determinants of airborne concentrations of volatile organic compounds in rural areas of Western Canada

We estimated the level and determinants of airborne concentrations of 26 volatile organic compounds (VOC) in rural Western Canada. A multisite, multimonth unbalanced two-factorial design was used to collect air samples at 1206 fixed sites across a geographic area associated with primary oil and gas industry in Alberta, northeastern British Columbia, and central and southern Saskatchewan from April 2001 to December 2002. Principal component factor analysis was used to group VOC into three mixtures. Factor I was a group of compounds dominated by benzene, toluene, ethyl-benzene, xylenes, and hexane. Factor II was mainly a group of vegetation-related monoterpenes and dichlorobenzenes. Factor III was a group of chlorinated VOC. Linear mixed effects models were applied to identify the determinants of airborne concentrations of VOC and evaluate the association between these factors and oil and gas facilities. Our results indicated that the studied VOC were present in small (ng/m3) quantities. Components of Factor I VOC showed a seasonal variation with maxima in winter and minima in summer, whereas components of Factor II displayed an opposite seasonal trend. Components of Factor III did not show a clear seasonal pattern. We observed that oil and gas facilities only contribute to airborne concentrations of components of Factor I. Proximity to batteries (within 2 km) was most influential in determining monthly airborne concentrations of components of Factor I, followed by gas and oil wells. Modification of batteries to reduce evaporation and leakage might be considered as a measure to control airborne concentrations of compounds such as benzene and toluene.     

The Los Angeles TEAM Study: personal exposures, indoor-outdoor air concentrations, and breath concentrations of 25 volatile organic compounds.

The U.S. Environmental Protection Agency and the California Air Resources Board studied the exposures of 51 residents of Los Angeles, California, to 25 volatile organic chemicals (VOCs) in air and drinking water in 1987. A major goal of the study was to measure personal, indoor, and outdoor air concentrations, and breath concentrations of VOCs in persons living in households that had previously been measured in 1984. Other goals were to confirm the marked day-night and seasonal differences observed in 1984; to determine room-to-room variability within homes; to determine source emission rates by measuring air exchange rates in each home; and to extend the coverage of chemicals by employing additional sampling and analysis methods. A total of 51 homes were visited in February of 1987, and 43 of these were revisited in July of 1987. The results confirmed previous TEAM Study findings of higher personal and indoor air concentrations than outdoor concentrations of all prevalent chemicals (except carbon tetrachloride); higher personal, indoor, and outdoor air concentrations in winter than in summer; and (in winter only) higher outdoor concentrations at night than in the daytime. New findings included the following: (1) room-to-room variability of 12-hour average concentrations was very small, indicating that a single monitor may be adequate for estimating indoor concentrations over this time span; (2) "whole-house" source emission rates were relatively constant during both seasons, with higher rates for odorous chemicals such as p-dichlorobenzene and limonene (often used in room air fresheners) than for other classes of chemicals; (3) breath concentrations measured during morning and evening were similar for most participants, suggesting the suitability of breath measurements for estimating exposure in the home; (4) limited data obtained on two additional chemicals-toluene and methylene chloride-indicated that both were prevalent at fairly high concentrations and that indoor air concentrations exceeded outdoor concentrations by a factor of about three.     

Concentrations of volatile organic compounds at a building with health and comfort complaints

For four separate periods over a 1-yr span, the concentrations of volatile organic compounds (VOCs) have been measured at a facility with a history of occupant complaints. The reported symptoms were characteristic of "sick building syndrome." This study was initiated to determine if VOC levels were higher than those measured in "complaint-free" buildings and, if so, to identify sources and other factors that might contribute to the elevated concentrations. VOCs were collected with passive samplers, using a sampling interval that lasted from 3 to 4 weeks. Following collection, the samplers were extracted, and the compounds in the extract were separated and identified using standard gas chromatographic-mass spectrometric procedures. Over 40 different organic compounds with concentrations in excess of 1 microgram/m3 were identified; several species had values greater than 100 micrograms/m3. For each of the first three sampling periods, the total concentration of VOCs detected using this methodology was in excess of 3 mg/m3. Sources of the identified compounds included cleaning products, floor wax, latex paints, and reentrained motor vehicle exhaust. However, the dominant source was the hydraulic system for the buildings' elevators. Compounds were volatilizing from the hydraulic fluid used in this system. Neither the elevator shafts nor the mechanical room housing the fluid reservoirs were vented to the outside. The problem was compounded by the relatively small amount of outside air used for ventilation at this facility (less than 6 L/sec [12 cfm]/occupant or about 1/4 air change/hr). At such low ventilation rates, compounds with strong sources can achieve high steady-state concentrations within the facility. Recommendations have been made to reduce the VOC levels at this site. Although implementing the recommendations will be costly, even a slight improvement in employee productivity will offset these costs.     

The respiratory effects of volatile organic compounds

Volatile organic compounds (VOCs) have been implicated as causative agents in asthma and building-related illness. To determine whether a mixture of VOCs could impair lung function or cause airway inflammation among subjects without bronchial hyperresponsiveness, the authors conducted a randomized, crossover-design trial of controlled human exposures to filtered air for four hours, VOCs at 25 mg/m(3) for four hours, and VOCs at 50 mg/m(3) for four hours, using a VOC mixture based on sampling of indoor environments. VOC exposures caused dose-related increases in lower respiratory, upper respiratory, and non-respiratory symptoms, with no significant change in lung function (FEV(1);, FVC, or FEF(25-75), nasal lavage cellularity or differential cell counts, induced sputum cellularity or differential cell counts, or biomarkers of airway inflammation, including IL-8, LTB(4), or albumin in nasal lavage or induced sputum samples. Atopic individuals had significantly reduced FEE(25-75 following exposure to VOCs at 50 mg/m(3), suggesting that these individuals may be more sensitive to the health effects of VOCs. The authors conclude that reductions in levels of VOCs to substantially less than 25 mg/m(3) are required if a "non-irritating" work environment is desired.     

Measurement of volatile organic compounds inside automobiles

The objective of the current study was to evaluate the types and concentrations of volatile organic compounds (VOCs) in the passenger cabin of selected sedan automobiles under static (parked, unventilated) and specified conditions of operation (i.e., driving the vehicle using air conditioning alone, vent mode alone, or driver's window half open). Data were collected on five different passenger sedan vehicles from three major automobile manufacturers. Airborne concentrations were assessed using 90-min time-weighted average (TWA) samples under U.S. Environmental Protection Agency (USEPA) Method IP-1B to assess individual VOC compounds and total VOCs (TVOCs) calibrated to toluene. Static vehicle testing demonstrated TVOC levels of approximately 400-800 microg/m(3) at warm interior vehicle temperatures (approximately 80 degrees F), whereas TVOCs at least fivefold higher were observed under extreme heat conditions (e.g., up to 145 degrees F). The profile of most prevalent individual VOC compounds varied considerably according to vehicle brand, age, and interior temperature tested, with predominant compounds including styrene, toluene, and 8- to 12-carbon VOCs. TVOC levels under varied operating conditions (and ventilation) were generally four- to eightfold lower (at approximately 50-160 microg/m(3)) than the static vehicle measurements under warm conditions, with the lowest measured levels generally observed in the trials with the driver's window half open. These data indicate that while relatively high concentrations of certain VOCs can be measured inside static vehicles under extreme heat conditions, normal modes of operation rapidly reduce the inside-vehicle VOC concentrations even when the air conditioning is set on recirculation mode.     

Elimination of volatile organic compounds in breath after exposure to occupational and environmental microenvironments.

Breath measurements offer the potential for a direct and noninvasive evaluation of human exposure to volatile organic compounds (VOCs) in the environments in which people live and work. This research study was conducted to further evaluate and develop the potential of this exposure assessment methodology. Several people were exposed to the atmosphere in six microenvironments for several hours. Air concentrations of VOCs were measured during these exposures and breath samples were collected and analyzed at multiple time points after the exposure to evaluate elimination kinetics for 21 VOCs. A new alveolar breath collection technique was applied. Elimination half-lives were estimated using a mono- and bi-exponential model. The alveolar breath collection and analysis methodology proved to be very useful for collecting many samples in short time intervals and this capability was very important for more accurately describing the initial phase of the decay curves. Breath decay curves were generated from samples collected over a four hour period after exposure for 21 of 24 target VOCs. A biexponential function generally provided a better fit for the decay data than did the monoexponential function, supporting a multi-compartment uptake and elimination model for the human body.     

occupational exposure to aromatic hydrocarbons at a coke plant: Part II. Exposure assessment of volatile organic compounds

The objective of the study is to assess the external and internal exposures to aromatic hydrocarbons in the tar and oil naphthalene distillation processes at a coke plant. 69 workers engaged as operators in tar and oil naphthalene distillation processes and 25 non-exposed subjects were examined. Personal analyses of the benzene, toluene, xylene isomers, ethylbenzene, naphthalene, indan, indene and acenaphthene in the breathing zone air allowed us to determine the time weighted average exposure levels to the aromatic hydrocarbons listed above. The internal exposure was investigated by measurement of the urinary excretion of naphthols, 2-methylphenol and dimethylphenol isomers by means of gas chromatography with a flame ionization detection (GC/FID). Urine metabolites were extracted after enzymatic hydrolysis by solid-phase extraction with styrene-divinylbenzene resin. The time-weighted average concentrations of the hydrocarbons detected in the breathing zone air shows that the exposure levels of the workers are relatively low in comparison to the exposure limits. Statistically significant differences between average concentrations of aromatic hydrocarbons (benzene, toluene, xylene isomers) determined at the workplaces in the tar distillation department have been found. Concentrations of the naphthalene and acenaphthene detected in workers from the oil distillation department are higher that those from the tar distillation department. Concentrations of naphthols, 2-methoxyphenol and dimethylphenol isomers in the urine of occupationally exposed workers were significantly higher than those of non-exposed subjects. Concentrations of the 2-methoxyphenol and dimethylphenol isomers in urine were significantly higher for the tar distillation workers, whereas concentrations of naphthols were higher for the oil naphthalene distillation workers. Operators at the tar and naphthalene oil distillation processes are simultaneously exposed to a mixture of different hydrocarbons, mainly benzene and naphthalene homologues.     

Personal exposure to volatile organic compounds in the Czech Republic

Personal exposures to volatile organic compounds (VOCs) were measured in the three industrial cities in the Czech Republic, Ostrava, Karvina and Havirov, while the city of Prague served as a control in a large-scale molecular epidemiological study identifying the impacts of air pollution on human health. Office workers from Ostrava and city policemen from Karvina, Havirov and Prague were monitored in the winter and summer of 2009. Only adult non-smokers participated in the study (N=160). Radiello-diffusive passive samplers were used to measure the exposure to benzene, toluene, ethylbenzene, meta- plus para-xylene and ortho-xylene (BTEX). All participants completed a personal questionnaire and a time-location-activity diary (TLAD). The average personal BTEX exposure levels in both seasons were 7.2/34.3/4.4/16.1?μg/m(3), respectively. The benzene levels were highest in winter in Karvina, Ostrava and Prague: 8.5, 7.2 and 5.3?μg/m(3), respectively. The personal exposures to BTEX were higher than the corresponding stationary monitoring levels detected in the individual localities (P<0.001; except m,p-xylene in summer). The indoor environment, ETS (environmental tobacco smoke), cooking, a home-heating fireplace or gas stove, automobile use and being in a restaurant were important predictors for benzene personal exposure. Ostrava's outdoor benzene pollution was a significant factor increasing the exposure of the Ostrava study participants in winter (P<0.05).     

挥发性有机物混合标准气体的配制

介绍一种简单、易操作、方便、灵活的配制标准有机气体混合物装置。以恒定压力作用在挥发性有机物混合液液面上,液体以恒定流速穿过一根长毛细管流出,由此制成标准发生源,流速的平均相对标准差为３．０％。将毛细管出口插入零空气流中,使液体挥发并混匀,以配成恒定浓度的有机物混合气体,改变发生源压力及稀释气流量即可改变混合气浓度,用气相色谱法测定浓度值,混合气浓度的平均相对标准差为５．７％,绝对误差±８％。比较实测值与计算值,两者无显著性差异。此配气方法适合于沸点在１５０℃以下有机混合物气体的配制     

室内挥发性有机物的来源及其健康效应

挥发性有机物 (VOCs)作为一大类空气污染物 ,是近几年来室内空气污染的热点问题 ,现代人一天之中有 90 %的时间在室内度过 ,所以VOCs对人体健康有着极大的危害 ,本文主要综述了VOCs的来源、种类及其对人体健康的影响。     

Determinants of exposure to volatile organic compounds in four Oklahoma cities

To begin to develop generalized models for estimating personal exposure to ambient air pollutants within diverse populations, the design of the Oklahoma Urban Air Toxics Study incorporated eight dichotomous macroenvironmental and household factors that were hypothesized to be potential determinants of exposure. Personal, indoor, and outdoor samples of volatile organic compounds (VOCs) were collected over 24-h monitoring periods in 42 households, together with activity diaries and data on the participants' residences. The distributions of the VOC concentrations were moderately to highly left-censored, and were mostly bimodal. The ATSDR minimal risk level (MRL) was exceeded in a small number of the samples. Personal and indoor concentrations tended to be higher than outdoor concentrations, indicating that indoor exposures were dominated by indoor sources. However, indoor concentrations were not correlated with the permeability of the residence, suggesting that the observed indoor concentrations reflected mostly localized, short-term emissions. The influence of the eight dichotomous factors and of the presence of an attached garage was evaluated using the Wilcoxon rank-sum test and by comparison of "excursion fractions", that is, the fractions of each distributions exceeding 10% of the MRL. Dry weather and absence of children in the household were found to be associated with higher exposures in personal or indoor exposures. Given the small sample size, it is possible that these factors were confounded with unidentified household characteristics or activities that were the true determinants of exposure.