Characteristics and health impacts of volatile organic compounds in photocopy centers

This study investigates the indoor air quality of typical photocopy centers in Taiwan to evaluate the human health risk following inhalation exposure. Both personal and area samplings were conducted at seven photocopy centers in the Tainan area from July 2002 to March 2003, which covered both summer and winter seasons in Taiwan. The benzene, toluene, ethylbenzene, xylenes, and styrene (BTEXS) measurements indicated no difference between personal and area samplings (P>0.05) and found that air conditioning improves indoor air quality. The additive factor at each photocopy center was significantly below 1.0, based on the current BTEXS permissible exposure limits in Taiwan. However, the mean benzene and styrene levels in the current study were 138 and 18 times, respectively, higher than those in another study conducted in the United States. Comparison of mass ratios of BTEXS with those of several chamber studies revealed that the photocopier is not the only volatile organic compound (VOC) source in photocopy centers. The lifetime cancer and noncancer risks for workers exposed to VOCs were also assessed. Results show that all seven centers in this study had a lifetime cancer risk exceeding 1x10(-6) (ranging from 2.5x10(-3) to 8.5x10(-5)). Regarding noncancer risk, levels of toluene, ethylbenzene, xylenes, and styrene were below the reference levels in all photocopy centers; however, the hazard indices for all still exceeded 1.0 (range 26.2-1.8) because of the high level of benzene in the photocopy centers.     

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).     

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.     

Worker exposure to volatile organic compounds in the vehicle repair industry

This study evaluated exposures among vehicle repair technicians to hexane, acetone, toluene, and total volatile organic compounds (VOCs). On randomly selected workdays, we observed a characteristic pattern of solvent use among 36 technicians employed in 10 repair shops, each of which used an aerosol solvent product. We obtained quantitative exposure measurements from a subset of nine technicians (employed in three of these shops) who used an aerosol product containing hexane (25-35%), acetone (45-55%), and toluene (5-10%). The time-weighted average (TWA) exposure concentration for task-length breathing zone (BZ) samples (n = 23) was 36 mg/m(3) for hexane, 50 mg/m(3) for acetone, and 10 mg/m(3) for toluene. The TWA area concentrations (n = 49) obtained contemporaneously with BZ samples ranged from 25% to 35% of the BZ concentrations. The solvent emission rate (grams emitted/task time) was correlated with the total VOC exposure concentration (R(2) = 0.45). The proportions of VOCs in the BZ samples were highly correlated (r = 0.89 to 0.95) and were similar to those of the bulk product. Continuous exposure measurements for total VOCs (n = 1238) during 26 tasks produced a mean BZ VOC "pulse" of 394 mg/m(3) within 1 min following initiation of solvent spraying. The geometric mean air speed was 5.2 meters/min in the work areas (n = 870) and was associated with 0.8 air changes per minute in the BZ. The findings suggest that vehicle repair technicians who use aerosol solvent products experience episodic, inhalation exposures to the VOCs contained in these products, and the proportions of VOCs in the breathing zone are similar to those of the bulk product. Because acetone appears to amplify the severity and duration of the neurotoxic effects of n-hexane, products formulated with both hexane and acetone should be avoided. Further evaluation of exposures to VOCs is needed in this industry, along with information on effective alternatives to aerosol solvent products.     

The influence of personal activities on exposure to volatile organic compounds

Seven persons volunteered to perform 25 common activities thought to increase personal exposure to volatile organic chemicals (VOCs) during a 3-day monitoring period. Personal, indoor, and outdoor air samples were collected on Tenax cartridges three times per day (evening, overnight, and daytime) and analyzed by GC-MS for 17 target VOCs. Samples of exhaled breath were also collected before and after each monitoring period. About 20 activities resulted in increasing exposure to one or more of the target VOCs, often by factors of 10, sometimes by factors of 100, compared to exposures during the sleep period. These concentrations were far above the highest observed outdoor concentrations during the length of the study. Breath levels were often significantly correlated with previous personal exposures. Major exposures were associated with use of deodorizers (p-dichlorobenzene); washing clothes and dishes (chloroform); visiting a dry cleaners (1,1,1-trichloroethane, tetrachloroethylene); smoking (benzene, styrene); cleaning a car engine (xylenes, ethylbenzene, tetrachloroethylene); painting and using paint remover (n-decane, n-undecane); and working in a scientific laboratory (many VOCs). Continuously elevated indoor air levels of p-dichlorobenzene, trichloroethylene, 1,1,1-trichloroethane, carbon tetrachloride, decane, and undecane were noted in several homes and attributed to unknown indoor sources. Measurements of exhaled breath suggested biological residence times in tissue of 12-18 hr and 20-30 hr for 1,1,1-trichloroethane and p-dichlorobenzene, respectively.     

Risk assessment of exposure to volatile organic compounds in different indoor environments

The lifetime cancer risks of exposure of cooks and food service workers, office workers, housewives, and schoolchildren in Hong Kong to volatile organic compounds (VOCs) in their respective indoor premises during normal indoor activities were assessed. The estimated cancer risk for housewives was the highest, and the second-highest lifetime cancer risk to VOC exposure was for the groups of food service and office workers. Within a certain group of the population, the lifetime cancer risk of the home living room was one to two orders of magnitude higher than that in other indoor environments. The estimated lifetime risks of food service workers were about two times that of office workers. Furthermore, the cancer risks of working in kitchen environments were approximately two times higher than the risks arising from studying in air-conditioned classrooms. The bus riders had higher average lifetime cancer risks than those travelling by Mass Transit Railway. For all target groups of people, the findings of this study show that the exposures to VOCs may lead to lifetime risks higher than 1 x 10(-6). Seven indoor environments were selected for the measurement of human exposure and the estimation of the corresponding lifetime cancer risks. The lifetime risks with 8-h average daily exposures to individual VOCs in individual environments were compared. People in a smoking home had the highest cancer risk, while students in an air-conditioned classroom had the lowest risk of cancer. Benzene accounted for about or more than 40% of the lifetime cancer risks for each category of indoor environment. Nonsmoking and smoking residences in Hong Kong had cancer risks associated with 8-h exposures of benzene above 1.8 x 10(-5) and 8.0 x 10(-5), respectively. The cancer risks associated with 1,1-dichloroethene, chloroform, methylene chloride, trichloroethene, and tetrachloroethene became more significant at selected homes and restaurants. Higher lifetime cancer risks due to exposure to styrene were only observed in the administrative and printing offices and air-conditioned classrooms. Higher lifetime cancer risks related to chloroform exposures were observed at the restaurant and the canteen.     

低浓度挥发性有机化合物被动式个体采样器的研究

研制了扩散式挥发性有机化合物（ＶＯＣｓ）个体采样器,适用于对环境空气中和非职业性个体接触ＶＯＣｓ的监测。在风速１０～２６０ｃｍ／ｓ,相对湿度为３０％～８０％,温度为１０～３０℃的范围内使用,采样速率分别为苯：２５．７４ｍｌ／ｍｉｎ,甲苯：２５．１６ｍｌ／ｍｉｎ,四氯乙烯：２５．８５ｍｌ／ｍｉｎ,对－二甲苯：８．１６ｍｌ／ｍｉｎ,苯乙烯：６．４７ｍｌ／ｍｉｎ。与主动式活性炭纤维（ＡＣＦ）管采样法比较,本个体采样器测定空气中靶ＶＯＣｓ的总不确定度均在±２５％以内。     

Children's exposure to volatile organic compounds as determined by longitudinal measurements in blood

Blood concentrations of 11 volatile organic compounds (VOCs) were measured up to four times over 2 years in a probability sample of more than 150 children from two poor, minority neighborhoods in Minneapolis, Minnesota. Blood levels of benzene, carbon tetrachloride, trichloroethene, and m-/p-xylene were comparable with those measured in selected adults from the Third National Health and Nutrition Examination Survey (NHANES III), whereas concentrations of ethylbenzene, tetrachloroethylene, toluene, 1,1,1-trichloroethane, and o-xylene were two or more times lower in the children. Blood levels of styrene were more than twice as high, and for about 10% of the children 1,4-dichlorobenzene levels were greater than or equal to 10 times higher compared with NHANES III subjects. We observed strong statistical associations between numerous pairwise combinations of individual VOCs in blood (e.g., benzene and m-/p-xylene, m-/p-xylene and o-xylene, 1,1,1-trichloroethane and m-/p-xylene, and 1,1,1-trichloroethane and trichloroethene). Between-child variability was higher than within-child variability for 1,4-dichlorobenzene and tetrachloroethylene. Between- and within-child variability were approximately the same for ethylbenzene and 1,1,1-trichloroethane, and between-child was lower than within-child variability for the other seven compounds. Two-day, integrated personal air measurements explained almost 79% of the variance in blood levels for 1,4-dichlorobenzene and approximately 20% for tetrachloroethylene, toluene, m-/p-xylene, and o-xylene. Personal air measurements explained much less of the variance (between 0.5 and 8%) for trichloroethene, styrene, benzene, and ethylbenzene. We observed no significant statistical associations between total urinary cotinine (a biomarker for exposure to environmental tobacco smoke) and blood VOC concentrations. For siblings living in the same household, we found strong statistical associations between measured blood VOC concentrations.     

Public bus and taxicab drivers' work-time exposure to aromatic volatile organic compounds

Information on the work-time exposure of public bus and taxicab drivers to volatile organic compounds (VOCs) may be a critical factor in exploring the association between occupational exposure and health effects. Accordingly, this study evaluated the work-time VOC exposure of public bus and taxicab drivers by measurement of six selected aromatic VOC concentrations in the personal air of public bus and taxicab drivers during winter and summer. Two groups of five public bus drivers (smokers and nonsmokers) and two groups of five taxicab drivers (smokers and nonsmokers) were recruited for the study. The taxicab drivers were found to be exposed to higher aromatic compound levels than the bus drivers during their daily work time. The personal exposure of the bus and taxicab drivers was influenced by whether or not they smoked plus the season. It was also established that the potential exposure of bus drivers to aromatic VOCs did not exceed that of an unemployed reference group, whereas the potential exposure of taxicab drivers did. Meanwhile, based on comparison of the calculated in-vehicle concentrations with those from a previous study, the VOC levels inside public buses and taxicabs were found to be lower than those inside automobiles.     

Source apportionment of exposure to toxic volatile organic compounds using positive matrix factorization

Data from the Total Exposure Assessment Methodology studies, conducted from 1980 to 1987 in New Jersey (NJ) and California (CA), and the 1990 California Indoor Exposure study were analyzed using positive matrix factorization, a receptor-oriented source apportionment model. Personal exposure and outdoor concentrations of 14 and 17 toxic volatile organic compounds (VOCs) were studied from the NJ and CA data, respectively. Analyzing both the personal exposure and outdoor concentrations made it possible to compare toxic VOCs in outdoor air and exposure resulting from personal activities. Regression analyses of the measured concentrations versus the factor scores were performed to determine the relative contribution of each factor to total exposure concentrations. Activity patterns of the NJ and CA participants were examined to determine whether reported exposures to specific sources correspond to higher estimated contributions from the factor identified with that source. For a subset of VOCs, a preliminary analysis to determine irritancy-based contributions of factors to exposures was carried out. Major source types of toxic VOCs in both NJ and CA appear to be aromatic sources resembling automobile exhaust, gasoline vapor, or environmental tobacco smoke for personal exposures, and automobile exhaust or gasoline vapors for outdoor concentrations.     

Evaluation of employee exposure to organic tin compounds used as stabilizers at PVC processing facilities

Organic tin compounds are primary substances used as heat stabilizers by the polyvinyl chloride (PVC) industry. The use of these compounds in the PVC industry is generally well controlled, usually by automated processes. This study was conducted to provide an overview of worker exposure to organic tin compounds at PVC processing facilities and to verify that these exposures are below the threshold limit value (TLV((R))) set by the American Conference of Governmental Industrial Hygienists for organic tin. The basis of the TLV indicates the principal concern is to minimize adverse effects on immune function and the central nervous system from airborne exposure to organic tin. The TLV has a skin designation based on the potential for percutaneous absorption; the TLVs for inhalation exposures are based on the presumption that there is no concurrent exposure via the skin and oral ingestion routes.Personal exposure monitoring was conducted following the National Institute for Occupational Safety and Health (NIOSH) 5504 sampling method and a modified version of the NIOSH analytical method. The results were reported as"total tin."The data indicated no average exposure levels for individual tasks exceeded the organic tin TLV, and 96%of results the samples were less than 20%of the TLV. Only 1 sample of 102 exceeded the TLV, and the individual was wearing appropriate respiratory protection. Subsequent investigation indicated the highest exposures occurred while the operators were conducting tasks that included manual handling of the organic tin compounds. These data suggest manual operations may have a greater potential for organic tin exposure.     

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.     

Association between personal exposure to volatile organic compounds and asthma among US adult population

Objectives There is growing concern about adverse respiratory health effects from exposure to indoor air pollution. The purpose of this study was to analyze association between exposure to volatile organic compounds (VOC) and asthma in adults. Methods This study utilized passive personal exposure data on ten VOC collected as part of the National Health and Nutrition Examination Survey (NHANES) 1999–2000. A total of 550 subjects who were of non-Hispanic whites, Mexican-Americans, or non-Hispanic Blacks race/ethnicity were included in this analysis. The primary outcome variable was physician-diagnosed asthma and the secondary outcome variable was presence of wheezing in the previous 12 months among those without physician-diagnosed asthma. Exploratory factor analysis was used to generate factor scores to group VOCs, which were included as indicator variables in the analyses. Associations between exposure to VOCs, physician-diagnosed asthma, and wheezing in the previous 12 months were evaluated using multiple logistic regression analyses. Odds ratios are for 1-U increase in level of exposure. Results Seven of the ten VOC variables loaded on two factors, “aromatic compounds” and “chlorinated hydrocarbons.” The geometric mean concentration of VOCs varied from as low as 0.03 μg/m³ for trichloroethene to as high as 14.33 μg/m³ for toluene. Mexican-Americans had the highest personal exposures to benzene (geometric mean = 2.38 μg/m³) as compared to non-Hispanic whites (geometric mean = 1.15 μg/m³) and non-Hispanic Blacks (geometric mean = 1.07 μg/m³). The odds of physician-diagnosed asthma were significantly higher among those exposed to aromatic compounds (Adjusted OR = 1.63, 95% CI: 1.17–2.27). Among those subjects never diagnosed by a physician to have asthma, a significantly increased odds of one to two wheezing attacks were observed for aromatic compounds (Adjusted OR = 1.68, 95% CI: 1.08–2.61) and chlorinated hydrocarbons (Adjusted OR = 1.50, 95% CI: 1.01–2.23) as compared to no wheezing. No association with three wheezing attacks or more was observed in the study. Conclusion In this cross-sectional study of a representative sample of the US population, environmental exposures to VOCs, especially aromatic compounds, were associated with adverse respiratory effects. An erratum to this article can be found at     

Human exposure to volatile organic compounds: a comparison of organic vapor monitoring badge levels with blood levels

We undertook a study in Albany, New York, to investigate whether volatile organic compounds (VOCs) were measurable in the blood and in the breathing-zone air of people exposed to gasoline fumes and automotive exhaust. We sampled blood of 40 subjects, placed organic vapor badges on 40 subjects, and obtained personal breathing-zone samples from 24 subjects. We limited this analysis to 19 subjects who wore the organic vapor badges for at least 5 h. VOC levels, as determined by the organic vapor badges, were highly correlated with blood levels of these same compounds. Using detection in blood as the gold standard, we found the badges to be more sensitive than conventional charcoal tube samples in detecting low levels of methyl tert-butyl ether (0.60 vs 0.08), toluene (0.95 vs 0.64), and o-xylene (0.85 vs 0.64). In this study, organic vapor badges provided data on VOC exposure that correlated with blood assay results. These organic vapor badges might provide a convenient means of determining human exposure to VOCs in epidemiologic studies.     

Migration of volatile organic compounds from attached garages to residences: a major exposure source

Vehicle garages often contain high concentrations of volatile organic compounds (VOCs) that may migrate into adjoining residences. This study characterizes VOC concentrations, exposures, airflows, and source apportionments in 15 single-family houses with attached garages in southeast Michigan. Fieldwork included inspections to determine possible VOC sources, deployment of perfluorocarbon tracer (PFT) sources in garages and occupied spaces, and measurements of PFT, VOC, and CO(2) concentrations over a 4-day period. Air exchange rates (AERs) averaged 0.43+/-0.37 h(-1) in the houses and 0.77+/-0.51 h(-1) in the garages, and air flows from garages to houses averaged 6.5+/-5.3% of the houses' overall air exchange. A total of 39 VOC species were detected indoors, 36 in the garage, and 20 in ambient air. Garages showed high levels of gasoline-related VOCs, e.g., benzene averaged 37+/-39 microg m(-3). Garage/indoor ratios and multizone IAQ models show that nearly all of the benzene and most of the fuel-related aromatics in the houses resulted from garage sources, confirming earlier reports that suggested the importance of attached garages. Moreover, doses of VOCs such as benzene experienced by non-smoking individuals living in houses with attached garages are dominated by emissions in garages, a result of exposures occurring in both garage and house microenvironments. All of this strongly suggests the need to better control VOC emissions in garages and contaminant migration through the garage-house interface.     

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.     

Occupational exposure to volatile organic compounds and mitigation by push-pull local exhaust ventilation in printing plants

The extensive use of multiple organic solvents in offset lithographic printing causing high emissions of volatile organic compounds (VOCs) indeed poses a serious risk to printing workers' health. In this study, indoor air quality (IAQ) assessments were carried out in seven printing plants and the main objectives were to understand the effect of VOC emissions on IAQ and develop effective mitigation measures to protect workers. The thorough gas chromatography/mass spectrometry (GC/MS) measurements showed that although a variety of VOCs were presented in the indoor air, none of them was found close to individual 8-h time-weighted average (TWA) of the occupational exposure limit (OEL). The additive effect was also found below the critical value of unity. However, short-term personal exposure to total volatile organic compounds (TVOCs) was exceedingly high when a print worker carried out blanket and ink roller cleaning procedures. Therefore, the occupational health risk was mainly due to repeated short-term exposures during intermittent VOC-emitting procedures rather than long-term exposure to background VOCs. Push-pull local exhaust ventilation (LEV) was identified as an effective mitigation measure. Computational fluid dynamics (CFD) analysis was conducted to study the push-pull LEV operation. It was found that there existed a threshold LEV air flow rate for an abrupt reduction in the worker's exposure to VOCs. The reduction was less sensitive when the LEV airflow was further increased beyond the threshold. These phenomena, consistent with experimental results reported by other investigators, were explained by detailed CFD analysis showing the competition between the general ventilation and the push-pull LEV to become the dominating driving force for the resultant local flow pattern.     

环境中挥发性有机化合物接触量监测指标的研究

研究了挥发性有机化合物 (VOCs)接触量的监测指标。采用热解吸毛细管气相色谱法测定环境中和呼出气中VOCs ;采用了固相微萃取 -气相色谱法测定血中VOCs。实验结果表明 :接触组人群所暴露的环境空气中、呼出气中以及血中VOCs浓度均高于对照组。结果提示 ,血中的VOCs特异、敏感 ,是评价个体接触VOCs较好的指标     

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.