Sensory and Analytical Evaluations of Paints With and Without Texanol

Nov 30, 2007 - Perception of odor can figure prominently in complaints about indoor air, yet identification of the responsible compound(s) is often di...
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Environ. Sci. Technol. 2008, 42, 243–248

Sensory and Analytical Evaluations of Paints With and Without Texanol M I C H E L L E G A L L A G H E R , * ,‡ PAMELA DALTON,‡ LAURA SITVARIN,‡ A N D G E O R G E P R E T I †,‡,| Monell Chemical Senses Center, 3500 Market Street, Philadelphia, Pennsylvania 19104 and Department of Dermatology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104

Received June 25, 2007. Revised manuscript received August 28, 2007. Accepted September 26, 2007.

Perception of odor can figure prominently in complaints about indoor air, yet identification of the responsible compound(s) is often difficult. For example, paint emissions contain a variety of odorous volatile organic compounds (VOCs) which may trigger reports of irritation and upper respiratory health effects. Texanol ester alcohol (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate), a paint coalescing agent, is frequently associated with the “persistent, characteristic odor” of water-based paint. To evaluate the sensory impact of Texanol, naïve (unfamiliar with paint constituents) and experienced (familiar with paint constituents) subjects evaluated the odor properties of paints with and without Texanol. VOC emissions from neat paint and paint applied to gypsum wallboard were collected via solidphase microextraction and analyzed by gas chromatography/ mass spectrometry and gas chromatography/olfactometry. Regardless of subjects’ prior experience, aromatic hydrocarbons and oxygenated compounds, introduced from other paint additives and not Texanol, were most commonly associated with paint odor. However, quantitative sensory techniques demonstrated that addition of Texanol to paints led to an overall increase in the perceived intensity of the coating. The combined use of these techniques proved to be an effective methodology for analyzing the structure of paint volatiles and their sensory properties and holds promise for solving many odorous indoor air problems.

Introduction The composition of the ambient air in indoor environments can be influenced by multiple emission sources including rugs, furniture, human occupants, and paint. Odors emanating from these sources may elicit real or imagined reports of respiratory irritation and health problems. However, the odorous compounds present in indoor air may only be minor components of a complex mixture of volatile organic compounds (VOCs). As a result, the techniques often employed for collection and analysis of indoor air mixtures (e.g., collection on solid absorbents with thermal desorption and gas chromatography/mass spectrometry; 1–3) will reveal the presence of numerous compounds, but will not tell * Corresponding author phone (267) 519-4925; fax: (267) 519-4925; e-mail: [email protected]. † Current Address: Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104. ‡ Monell Chemical Senses Center. | Department of Dermatology. 10.1021/es071555y CCC: $40.75

Published on Web 11/30/2007

 2008 American Chemical Society

investigators which components produce odor. Thus, when identification of the odor-causing culprit in a complex mixture is key, it is often essential to employ human olfactory abilities to guide the analytical effort. Water-based paints are known to emit a variety of VOCs (4, 5). These paints have been extensively studied for their possible health hazards and impact on indoor air quality (6, 7). In comparison, relatively little has been reported on the human sensory experiences involving the compounds responsible for paint odor and its persistence in indoor air. Although the health impact of emissions from water-based paints have not been shown to be appreciable, the sensory impact of these coatings may be far greater. Reports of annoyance and/or irritation are frequently associated with the odors from paint emissions, particularly those odors which persist beyond a few hours following application. Texanol ester alcohol (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate; henceforth Texanol (a registered trademark of the Eastman Chemical Company)) is a common coalescing agent used in latex paints; it provides high levels of film integrity at low levels of use (8). Texanol has two isomers (Figure 1). Based on both exposure and toxicity testing, Texanol has been shown to have a low level of toxicity, combined with low potential for human exposure (9). Although the potential for frequency of exposure in the population is high, the level of exposure is low (average room concentration of 0.37 ppm during roller application of latex paint) during the time a typical consumer spends painting (10). With a molecular weight of 216.32 and a boiling point of 254 °C, the low volatility of Texanol results in a slow emission rate from the surface of the paint matrix. There is scant data on the odor detection threshold for Texanol, but estimates obtained from one experimental study suggest that the odor can be detectable in the 10–30 ppb range (11) and will be readily detected by all at slightly higher concentrations. For these reasons, it should not be surprising that paints containing Texanol have been described as having a weak, but mildly unpleasant odor that can persist for days beyond the initial application. Regardless of the complexity of VOC emissions from painted surfaces, the odor associated with paint is often ascribed solely to the presence of Texanol. The possibility that this characteristic odor is misattributed to Texanol, combined with the recent increase in consumer preference for low-odor paints, lends urgency to understanding the components of paints which are responsible for any persistent olfactory impact. In an attempt to correlate these anecdotal olfactory impressions with the compounds responsible for the odors, this paper describes the dual sensory and analytical evaluations of three experimental water-based paints. The paints used in this study were analyzed using solid-phase microextraction (SPME) in combination with gas chromatography/olfactometry (GC/O) and gas chromatography/ mass spectrometry (GC/MS). The GC/O technique employs the human nose as a detector and enables the investigator to determine which areas of a complex chromatogram contain odorants of interest. In this study, we also investigated whether individuals having multiple years of professional experience with paints and their components, including Texanol, would be better able than naïve individuals to identify the odor-causing compounds, including Texanol, in paints applied to gypsum wallboard and analyzed via GC/O.

Material and Methods Subjects. Six subjects (four males, two females) ranging in age from 18 to 60 years old (with a mean age of 35) served as the “naïve” evaluators in the first phase of this study. The VOL. 42, NO. 1, 2008 / ENVIRONMENTAL SCIENCE & TECHNOLOGY

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FIGURE 1. The structures of the two isomers of Texanol. participants were naïve in that they were unfamiliar with the constituents of water-based paints and especially the odor of Texanol. Five currently employed paint chemists (three females, two males) served as the “experienced” evaluators in the second phase of this study. They ranged in age from 20 to 64 years old, with a mean age of 40. These subjects were all familiar with the constituents of water-based paints and particularly the odor of Texanol from their work in the paint industry. All subjects signed informed consents which had been approved by the University of Pennsylvania Institutional Review Board. All volunteers were screened for normal olfactory function. This testing was seen as especially important for the paint chemists given the nature of their occupation and their probable history of exposure to solvents, which can alter and impair olfactory sensitivity (12, 13). Three types of tests were used: detection sensitivity for phenylethyl alcohol, forced-choice discrimination of five qualitatively different odorous chemicals (phenylethyl alcohol, amyl acetate, eucalyptol, menthone, and acetic acid) (14) and a 20 item odor identification test, consisting of numerous everyday food and household odors (15, 16). Stimuli. The evaluated stimuli were three semi-gloss paint formulations (supplied by the Eastman Chemical Company, Kingsport, TN). The first formulation (Paint A) contained Texanol, plus a variety of aromatic hydrocarbons found in some of the paint additives. The second formulation (Paint B) was identical to the first, except for the absence of Texanol. The third formulation (Paint C) contained Texanol, but lacked the paint additives containing the aromatic hydrocarbons. Paint C was prepared to provide additional information on whether subjects would identify paint odors in samples without the aromatic hydrocarbons. For a complete description of the paint compositions, please see description S1 and Table S1 in the Supporting Information. For both the sensory and analytical evaluations, the three paint formulations (A, B, and C) were painted on gypsum wallboard. The wallboard (3/8” Gold Bond, National Gypsum Co, NC) was cut into 8 by 8 in squares, and each was coated with 15 mL of one of the three paints using a fresh 2” roller for each sample. Solid-Phase Microextraction (SPME). SPME is a proprietary technology (of Supelco Inc., Bellefonte, PA) that employs a thin fused-silica fiber coated with an adsorbent. The fibers used for collection of paint volatiles were the 2 cm, 50/30 µm Divinylbenzene/Carboxen polydimethylsiloxane (DVB/Carboxen/PDMS) “Stableflex” fibers (Supelco Corp.). VOCs evolving from a surface are exposed to the coated fiber and dissolve or absorb in the coating. The fiber with concentrated volatiles is then transferred to the GC/MS for desorption, separation, and analysis. This powerful technology offers a simple methodology for collecting VOCs directly over any paint surface, allowing for a very detailed analysis of trace amounts of compounds from a small area. Gas Chromatography/Olfactometry (GC/O). GC/O is a technique which pairs human olfactory ability with analytical instrumentation to better identify the odorous constituents of a complex mixture. A Finnigan 9001 gas chromatograph with a specially fitted “sniffer port” was used for these analyses. For a full description of how this technique works and the specific protocol that was used in this research, please 244

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see description S2 in the Supporting Information. This technique is commonly used in the flavor and fragrance industry to identify odorants in complex natural mixtures from plants, fruits and foods (17, 18). Gas Chromatography/Mass Spectrometry (GC/MS). A Thermoquest/Finnigan Voyager GC/MS with Xcalibur software (ThermoElectron Corp., San Jose, CA) was used for all analyses. A polar, Stabilwax column, 30 m × 0.32 mm with 1.0 µ coating, (Restek Corp., Bellefonte, PA) was used for separation and analysis of the volatiles extracted from the samples. For a full description of the GC/MS protocol and parameters, please see description S3 in the Supporting Information. Analytical Evaluation using GC/MS. 1 mL of Paint A (containing Texanol) which had been placed in a 1 L I-Chem bottle (A Nalge Company, New Castle, DE) was allowed to equilibrate at room temperature for 30 min. A SPME fiber was then exposed to the headspace of the bottle for 30 min, and the collected volatiles were injected into the GC/MS and analyzed. This procedure was repeated for Paints B and C. The three paint formulations (A, B, and C) were painted on wallboard and were sampled at multiple time points after painting (2 h, 6 h, 24 h, 72 h, and 1 week). At each time point, a glass funnel (10 cm i.d.) was placed over the wallboard. The funnel narrows sufficiently to hold, in-place, a SPME device. The SPME fiber was exposed above the painted wallboard for 30 min and then injected into the GC/MS for desorption, separation, compound identification, and quantification. Procedure for Phase I “Naïve” Subjects. Each subject was instructed to first smell each of the neat paint samples (1 mL) inside an I-Chem bottle and to record his or her impressions of the paint odor as a whole. 1 mL of Paint A (containing Texanol) which had been placed in a 1 L I-Chem bottle was allowed to equilibrate at room temperature for 30 min. A SPME fiber was then exposed to the headspace of the bottle for 30 min and the collected volatiles were injected into the GC/O to provide fresh samples for the naïve subjects. The subjects were then asked to record the time and description of all odors eluting from the “sniffer port” of the GC/O during a 40 min run. They were also asked when they perceived the odor which most resembled the characteristic quality of the whole paint sample, which they had sniffed prior to their GC/O evaluation. This procedure was repeated for Paint B. Note: The naïve subjects did not evaluate Paint C, as it was not available in this first part of the study. The subjects then were asked to rate the odor intensity of blank (unpainted) wallboard, as well as nine wallboard samples coated with one of the three paint formulations (A, B, and C) and painted either 24, 48, or 96 h previously. The intensity ratings were based on the labeled magnitude scale (LMS; (19)). Procedure for Phase 2 “Paint Chemists”. The paint chemists followed essentially the same testing procedure as the naïve subjects with a few exceptions. Each paint chemist rated both the odor intensity and quality of blank wallboard, as well as nine wallboard samples coated with one of the three paint formulations (A, B, and C) and painted either 24, 48, or 96 h previously. The intensity ratings were based on the labeled magnitude scale (LMS; (19)). However, the GC/O analysis for these subjects was based on 30 min SPME collections from painted wallboard samples which had been coated 24 h prior to the evaluation. The paint chemists completed the GC/O experiment for all three paints (A, B, and C). As was true for the naïve subjects, immediately prior to starting the GC/O experiment, the volunteers were asked to sniff a sample of the painted wallboard so that they could better identify the “characteristic” paint odor if/when it occurred in the GC/O evaluation.

FIGURE 2. Odor intensity ratings of painted wallboards by naive subjects at three post-application times. A ) Texanol + aromatics, B ) no Texanol + aromatics, and C ) Texanol + no aromatics. Blank ) blank wallboard. Intensity ratings were based on the labeled magnitude scale (LMS) (see ref 19). Repeated-measures analysis of variance (Statistica 6.1) revealed significant differences in rated intensity for all three paints, F (2,8) ) 50.2, p ) 0.003.

FIGURE 3. Odor intensity ratings of painted wallboards by paint chemists at three post-application times. A ) Texanol + aromatics, B ) no Texanol + aromatics, and C ) Texanol + no aromatics. Blank ) blank wallboard. Intensity ratings were based on the labeled magnitude scale (LMS) (see ref 19). Repeated-measures analysis of variance (Statistica 6.1) revealed a significant difference in rated intensity, F(2,8) ) 41.5, p ) 0.0035, with intensity Paint A being significantly different than Paint B, but only marginally (p ) 0.06) different from Paint C.

Results and Discussion Olfactory Acuity. With one exception, all volunteers scored within the normal range for all tests of olfactory ability. However, there were no concerns that impaired olfactory ability among these individuals would impair their evaluations of the paint compounds of interest in this study (see description S4, Supporting Information). Evaluation of Painted Wallboard Samples. Both naïve and experienced subjects rated the intensity of wallboard painted with the three paints at 24, 48, and 96 h. Figures 2 and 3 show the mean odor intensity ratings given to the wallboard samples painted with the three different coatings at three different time intervals, and statistically significant differences were observed. Both naïve and experienced subjects rated the wallboards similarly. The ratings of odor intensity for two of the three formulations (A and B) decreased or stayed about the same as the paint aged. This trend was not true for the coating containing Texanol with no aromatics (Paint C), which appeared to increase in intensity from 24 to 48 h and then decrease. This trend may reflect the volatility of the Texanol in the absence of other compounds emanating from Paint C. As Paint C does not contain the volatile aromatics present in Paint A and B, there may be a lag time as to when the more nonvolatile compounds (such as Texanol) start to increase in perceived intensity. There was also evidence of perceptual additivity for the coating with both Texanol and aromatics (Paint A), which yielded the highest odor intensity ratings across all three

time intervals. As can be seen in Figures 2 and 3, the intensity ratings given to this paint appear to represent the sum of the intensities of the paint containing Texanol with no aromatics (Paint C) and the paint with aromatics, but no Texanol (Paint B). The paint with the second highest intensity rating was the coating containing Texanol with no aromatics (Paint C). The lowest intensity ratings were given to the coating containing aromatics with no Texanol (Paint B). Thus, it is apparent that Texanol odor does contribute both to the overall intensity of the coating as it dries and its persistence over the 96 h time interval. Phase 1: Testing with the Naïve Subjects. The two principal paint samples that were analyzed were A and B, with and without Texanol, respectively. Each of the subjects’ impressions is summarized in Tables S2 and S3 (see Supporting Information). Interestingly, there are many descriptors with the word “paint” in them regardless of the paint used. In addition, most of the descriptors using “paint” in Paint A, which contains Texanol, were given to compounds eluting before the elution time of Texanol (∼23 min). Similarly, when evaluating the odor of Paint B (which does NOT contain Texanol), five out of five naïve subjects associated volatiles coming out of the GC/O between 5 and 15 min as having paint-like qualities. The compounds eluting at this time are predominately aromatic compounds. These data suggest that the volatiles eluting prior to the emergence of Texanol carry many of the characteristic paint odorants. VOL. 42, NO. 1, 2008 / ENVIRONMENTAL SCIENCE & TECHNOLOGY

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GC/MS evaluation (see GC/MS section below) showed that the compounds yielding the most “paint” odor descriptors (retention times approximate) were n-butyl ether (3.19 min) and several aromatic hydrocarbons including trimethylbenzenes (9.71–12.01 min), ethylxylenes (11.65–12.72 min), and tetramethylbenzenes (14.06–15.50 min). Subsequent analyses of paint components revealed that many, if not all of these aromatic constituents, are part of the paint additives. Phase 2: Testing with the Paint Chemist Subjects. In addition to making odor intensity ratings, volunteers were also asked to characterize the quality of the odors they were rating in these samples (see Table S4 in the Supporting Information). While not all volunteers made qualitative assessments of each sample, there was a tendency among two of the raters to label all coatings as smelling “Texanollike”. This description was given even for the coating which did not contain Texanol, but which did contain aromatic hydrocarbons, suggesting an erroneous association of Texanol with the odors associated with the aromatics also present in paint formulations. However, the persistence of Texanol volatilizing off of the wallboard samples at longer time intervals was apparent, as two of the volunteers characterized the 96 h samples of Paints A and C as smelling “Texanollike”, whereas no one described the 96 h sample of Paint B with this characteristic. The experienced paint chemists completed a GC/O of each paint sample which had been painted 24 h prior to the experiment. Each of the volunteers’ observations is summarized in Table S5 (see the Supporting Information). In general, the most odor quality descriptions were given for the paint with both Texanol and aromatic hydrocarbons (Paint A). Three of the five paint chemists described a Texanol/paint-like odor eluting around 17.25–17.31 min (close to where dimethylsulfoxide [DMSO] elutes). Texanol actually elutes around 23 min. Odors also seemed to be notably present in this paint sample at 8.45–8.50 min (close to where propyl benzene elutes, described as sweet and isopropyl alcohol-like), 10.59–11.16 min (close to where mesitylene and propyl toluene elute, described as musty and rotten) and 14.00–16.00 min (close to where tetramethylbenzenes elute, described as minty, moldy, sweet, and paintlike). Interestingly, no one described a paint-like odor at the time when Texanol actually eluted. For the paint with Texanol and no aromatics (Paint C), the retention times where odors were most observed were at 4.22–4.37 min (close to where n-butyl ether elutes, described as sour, sweet, and funky), 13.56–14.44 min (close to where dimethyl pyridine elutes, described as paint, damp, and sulfur) and 17.26–17.33 min (close to where propylene glycol elutes, described as paint and monomer-like). A sulfur compound, tentatively identified as ditert-butyl disulfide by its mass spectrum, eluted at 11.20 min, and two other alkyl pyridines eluted at 13.63 and 14.31 min in the SPME-GC/MS analysis of a neat sample of Paint C. The disulfide compound and pyridines were not observed in the GC/MS TICS at 24 h, but may be detected by the human nose during GC/O and thus may contribute to the odors the subjects are reporting around 13.56–14.44 min. Again, a paint-like/Texanol odor was not observed by any of the volunteers at the time when Texanol eluted. For the paint with aromatics, but no Texanol (Paint B), the retention times in which odors were most described were 7.55–9.11 min (close to where propyl benzene and ethyl toluene elute, but described as ethyl acetate, isopropyl alcohol, and sulfur), 15.00–15.33 min (close to where tetramethylbenzene elutes, but described as rosy, monomer, and amine-like) and 17.39–17.45 min (close to where DMSO elutes, but described as musty and marshmallow-like). 246

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FIGURE 4. Total ion chromatograms (TICs) from the GC/MS analyses of neat samples of Paints A, B, and C. VOCs from 1 mL of each paint were collected by SPME for 30 min after equilibration in a 1 L I-Chem bottle. Although no Texanol was present, one volunteer did report smelling a Texanol odor at 19.57 min. The data suggest that the volatiles eluting prior to Texanol have many of the odor characteristics attributed to paint. The compounds yielding the most “paint-like” odor descriptions can be attributed to substituted benzenes and toluenes, as well as some other solvents (such as n-butyl ether, DMSO, and propylene glycol) eluting between 3 and 18 min These observations are consistent with the GC/O results completed in phase 1 with the naïve subjects. Slight variations in component retention times across injections of the same sample are in-part, responsible for ( 0.2–0.4 min differences in recordings of individual subject’s responses to the same component (see Tables S2–S5 in the Supporting Information). In addition, subjects (both naïve and experienced), seldom reported identical descriptors for the presumably same odorants. This variation may be due to both an individual’s olfactory sensitivity, as well as their inability to assign verbal labels to odors, a recognized phenomenon in olfactory studies (20). However, while both groups exhibited significant inconsistency in the labels applied to the various eluting compounds, the most consistent result we observed was the failure of either group to identify any odors similar to “paint” at or near the elution time of Texanol. Gas Chromatography/Mass Spectrometry (GC/MS). The total ion chromatograms (TICs) which display the array of VOCs from the three neat paints are shown in Figure 4. The three paint formulations were all analyzed both neat and on painted wallboard after 24 h of drying. The compounds found in the three paints after 24 h are listed in Table 1. Paint samples A and B are mainly comprised of aromatic hydrocarbons which elute prior to Texanol. In contrast, Paint C is relatively devoid of components except for solvents such as n-butyl ether and propylene glycol. GC/MS data acquired from directly above the painted wallboard samples of Paints A and C sampled at 2 h, 4 h, 6 h, 24 h, 72 h, and 1 week demonstrate the persistence of Texanol over time (representative TICs for Paint A are shown in Figure 5). Three representative aromatic compounds with different retention times (ethyltoluene, trimethylbenzene, and tetramethylbenzene) were selected to compare their relative concentrations with Texanol over time. The ratios for each of these compounds’ peak area/TIC intensities are shown in Table 2. After 72 h, the aromatic compounds decreased 2–15 fold in relative concentration, while the relative concentration of Texanol remained almost constant. After 1 week, the aromatics had decreased 3–300 fold in concentration. Texanol

TABLE 1. VOCs Found above Wallboard Coated with Either Paint A, B, or C (After 24 H Post-Painting) RT (min)

compound

Paint A

Paint B

Paint C

n-butyl ether unknown alkane propyl benzene ethyl toluene (isomer not specified) 1,3,5-trimethylbenzene (mesitylene)a ethyl toluene (isomer not specified) 1,2,4-trimethylbenzenea propyl toluene (isomer not specified) ethyl xylene (isomer not specified) 1,2,3-trimethylbenzene ethyl xylene (isomer not specified) ethyl xylene (isomer not specified) dimethyl pyridine (isomer not specified) ethyl xylene (isomer not specified) 1,2,4,5-tetramethybenzene (durene)a 1,2,3,4-tetramethylbenzene ethyl hexanola,b 1,2,3,5-tetramethylbenzene (isodurene) dimethyl sulfoxide (DMSO)a propylene glycola 2-(2-butoxyethoxy)ethanola,b Texanola Texanola

X X X X X X X X X X X X

X X X X X X X X X X X X

X

X X X X X X X X X X

X X X X X X X X

a

3.19 5.66 8.82 9.23 9.71 10.16 10.66 11.16 11.65 12.01 12.36 12.52 12.55 12.72 14.06 14.30 15.28 15.50 17.12 17.54 21.51 22.96 23.29

X

X X X X

a

Denotes RT (retention time) and mass spectrum were confirmed by injecting a standard solution of that compound into the GC/MS; b Denotes compounds that are present in room air.

FIGURE 5. TICs showing volatiles emanating from wallboard painted with Paint A, over time.

TABLE 2. Comparison of Selected Compound Peak Areas/TIC Intensity for Three Representative Aromatic Hydrocarbons and Texanol from Paint A over Indicated Time Intervals ethyl compound toluene trimethylbenzene tetramethylbenzene Texanol RT (min)

9.25

2h 6h 24 h 72 h 1 wk

3.57 2.48 1.25 0.23 0.01

10.66 14.30 compound peak area/TIC intensity 2.79 0.87 2.14 0.93 1.38 0.92 0.32 0.38 0.04 0.26

22.96 6.24 7.31 7.19 6.58 7.50

remained approximately the same concentration (relative to TIC intensity) even after one week. Texanol can hydrolyze to isobutyric acid over time, particularly under basic conditions; however, in these latex paints, this hydrolyzis is very minimal (21). A small amount (0.04% of total volatiles emitted) of isobutyric acid was found in Paint C after 1 week. Isobutyric acid was not observed in Paint C after 3 days and was not seen in Paints A and B even after one week. Isobutyric acid, therefore, should have had

no sensory impact on the GC/O experiments as the subjects only analyzed paint samples painted 24 h prior to the experiment. In studies that have measured the airborne concentrations of Texanol following field application with a roller and drying of water-based polyvinyl acetate paint, paints were applied using airless spraying of roller/brush methods in rooms having 0.5 or 5.0 air changes per hour (9, 10). Both personal breathing zone air samples, as well as fixed station air samples, were collected during application and 6 h, 24 h, and 1 week after application. With this technique, average concentrations decreased rapidly from 0.37 ppm during application to below 0.19 ppm at 24 h. Seven days following application, three out of four samples were below the 0.01 ppm limit of analytical detection. These results are consistent with a more recent study evaluating the emission of Texanol from painted gypsum wallboard over a similar time period, in which the concentration of Texanol reached a peak at 10 h, then decreased exponentially over the course of the next 90 h (1). The temporal profile of the emission rates of VOCs and Texanol has been shown to be dependent upon the substrate to which they are applied, as well as the time from application (1–3). Our paints were applied only onto gypsum, and all samples collected for sensory testing were evaluated at 24 h postapplication. Consequently, all subjects were presented with the same olfactory stimuli for rating. When compared with the aromatic hydrocarbons, however, it appears that the relative persistence of Texanol coupled with its low odor threshold (1), could lead to consumer reports of a weakly persistent odor following application. Understanding what compounds contribute to the characteristic odor of paint will assist in helping to reduce the overall odorous impact of paint, as well as illuminate which VOCs are being perceived by individuals at different time points following application. The latter knowledge can provide the necessary information to educate consumers who express unfounded concerns about potential or perceived hazards associated with exposure to paint volatiles. VOL. 42, NO. 1, 2008 / ENVIRONMENTAL SCIENCE & TECHNOLOGY

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Acknowledgments We are grateful to the Eastman Chemical Company for both technical and financial support. We would also like to thank all our volunteers who participated in this study, especially the following paint chemists who served as our “experienced” evaluators: Yaw Aidoo, John Allen, Felicia Andrews, Chuck Pohan, and Lauren Seals. We also thank Mr. Jason Eades, Mr. Marcus Jackson, and Mr. Jeff Plegaria for technical assistance.

Supporting Information Available Details regarding the paint formulations, the GC/MS, the GC/O and olfactory acuity can be found in descriptions S1S4, respectively. Table S1 provides the composition information of paint ingredients. Tables S2 and S3 provide sensory evaluations (GC/O) of Paints A and B (neat) by the naïve subjects. Table S4 provides quality evaluations by paint chemists of wallboards painted with Paints A, B, and C at three different time points post painting. The sensory evaluations (GC/O) of Paint A, B, and C (after 24 h postpainting) by the paint chemists can be found in Table S5. This material is available free of charge via the Internet at http://pubs.acs.org.

Literature Cited (1) Lin, C.-C.; Corsi, R. L. Texanol ester alcohol emissions from latex paints: Temporal variations and multi-component recoveries. Atmos. Environ. 2007, 41, 3225–3234. (2) Chang, J. C. S.; Tichenor, B. A.; Guo, Z.; Krebs, K. A. Substrate effects on VOC emissions from a latex paint. Indoor Air 1997, 7, 241–247. (3) Hodgson, A. T.; Rudd, A. F.; Beal, D.; Chandra, S. Volatile organic compound concentrations and emissions rates in new manufactured and site-built houses. Indoor Air 2000, 10, 178–192. (4) Censullo, A. C.; Jones, D. R.; Wills, M. T. Direct VOC analysis of water-based coatings by gas-chromatography and solid-phase microextraction. J. Coat. Technol. 1997, 69, 33–41. (5) Clausen, P. A. Emission of volatile and semivolatile organic compounds from waterborne paints - the effect of the film thickness. Indoor Air 1993, 3, 269–275. (6) Van Faassen, A.; Borm, P. J. A. Composition and health hazards of water-based construction paints: results from a survey in the Netherlands. Environ. Health. Perspect. 1991, 92, 147–154.

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