Association of Lung Function With Benzene, Toluene and Xylene (Btx) in End-exhaled Air in Gas Station Attendants

doi:10.21203/rs.3.rs-3332967/v1

Download PDF

Research Article

Association of Lung Function With Benzene, Toluene and Xylene (Btx) in End-exhaled Air in Gas Station Attendants

https://doi.org/10.21203/rs.3.rs-3332967/v1

This work is licensed under a CC BY 4.0 License

Version 1

posted

You are reading this latest preprint version

Background - Gas station attendants are exposed to benzene, toluene and xylenes (BTX) from fuels. The aim was to study the association between this exposure and spirometry parameters in gas station attendants and office workers as controls.

Method – In 44 male gas station attendants and 38 office workers in the Gampaha district of Sri Lanka, spirometry was performed according to the guidelines of the American Thoracic Society (ATS). Pre- and postshift end-exhaled air samples were collected from a subgroup of 20 gas station attendants and 11 office workers and analysed for BTX by gas chromatography‒mass spectrometry.

Results –The peak expiratory flow rate (PEF) and %-predicted PEF were significantly lower among gas station attendants compared to controls (p = 0.012). Among gas station attendants, the postshift sample benzene level showed a significant negative correlation with %-predicted forced vital capacity (FVC) (Spearman’s correlation coefficient of -0.683, p = 0.014). The %-predicted FVC was lower in gas station attendants working ≥ 5 years compared to those who worked < 5 years (82.71% ±12.53 vs 91.25%±7.50; p = 0.026). In controls, a distinct pattern was observed, indicating a moderate to strong association of postshift toluene and xylenes with all lung function parameters but not benzene. These results were adjusted for smoking.

Conclusion –In gas station attendants, we observed restrictive responses in spirometry that were most pronounced for the level of work-related benzene exposure and associated with duration of employment. Air pollutants other than BTX may have contributed to explaining our findings.

volatile organic compounds

gasoline

road traffic

biomonitoring

spirometry

Road traffic still relies primarily on fossil fuels, which leads to high levels of air pollution, specifically in urban areas. Such airborne contaminants include nitrogen oxides (NO_x), carbon monoxide (CO), carbon dioxide (CO₂), ozone (O₃), sulfur dioxide (SO₂), volatile organic compounds (VOC), and particulate matter (PM), which are all emitted from automobile exhaust ¹. Benzene, toluene, and p-, m-, and o-xylene (BTX) represent toxic VOCs primarily derived from gasoline fuel and exhaust fumes and are related to the propulsion of passenger cars, vans, and motorcycles, representing the most important sources in road traffic. Exposure to such pollutants results in respiratory symptoms ² and increased susceptibility to respiratory tract infections ^3,4 and lung cancer ⁵. Pulmonary restriction and airway obstruction with the involvement of small airways have been previously reported ^1,4,6.

Gas station attendants have an increased risk of exposure to fuel vapour by inhalation ⁷. Gas station attendants and workers in petrochemical industries in developing countries are particularly at risk for these deleterious effects because of the lack of adequate regulatory and protective mechanisms ³. The proximity of fuel stations to busy roads causes workers to also be exposed to air pollutants other than fuel vapours. Lungs and airways are primary targets for adverse effects of inhaled air contaminants ¹. The average duration of daily exposure exceeds approximately 10 h/day, especially if the employers provide overnight accommodations at the worksite. The duration of exposure may vary depending on their occupation tenure ⁸.

The health effects of exposure to fuel pollutants have not been assessed previously in Sri Lanka, a country with no self-service fuel stations and no imminenet plan to implement them in the near future. This study assessed lung function using spirometry in gas station attendants following long-term exposure to BTX. The aim of the project was to study the association between BTX exposure and spirometry parameters in gas station attendants and office workers as controls.

Study population

Fifty healthy male fuel attendants/handlers aged 20 to 65 years, employed for more than one year at fuel stations of the Gampaha District in the Western Province of Sri Lanka, were recruited. The gas station attendants were from 7 fuel stations. The control population comprised 50 healthy age-matched male white-collar workers residing in a suburban environment northwest of Colombo with a background exposure to air pollutants.

The duration of a shift, duration of employment, smoking status, presence of any health problems, symptoms of endocrine abnormalities and exposure to chemicals or fumes were recorded together with demographic characteristics (age, race, marital status, number of children and income). A physical examination was carried out, including measurement of height and weight. None of the study participants had a chest deformity.

Study area

Sri Lanka is an island located in South Asia, a developing nation with a GDP of 4,310 USD per capita ⁹. The Ceylon Petroleum Corporation (CPC), the nation's oil provider, is regulated by the Ministry of Petroleum Resources Development. The nation consumes close to 98,000 barrels of crude oil per day ¹⁰. With over 6.6 million vehicles on its roads ¹¹, the fuel to drive these vehicles is provided by petrol stations employing hundreds of workers across the country. The tropical climate facilitates the rapid evaporation of fuel components, and variable wind speeds make the exposures unique and somewhat different from countries in other climate zones. The study was carried out in the Western province of Sri Lanka from January 2018 - March 2019 (Additional file 1, Map of the study area).

End-exhaled air sampling

Exposure to BTX was studied in a subgroup of 20 gas station attendants and 11 controls. The method of exposure assessment by breath analyses as a method of human biomonitoring has been previously described ¹². Each participant provided an end-exhaled air sample using a BioVOC sampler (Markes, Llantrisant, UK) at the beginning of the shift (preshift) and the end of the shift (postshift). To prevent contaminants from interfering with our analysis, all analytical thermal desorption (ATD) tubes were precleaned by purging with helium 5.0 for four hours at 250°C. Each study participant exhaled completely into the BioVOC sampler through a cardboard mouthpiece. Immediately after the sample was collected, the components of interest were transferred to the ATD tube. ATD tubes were capped with brass compression caps, packed in a gastight container and stored at ambient temperature ¹².

Analysis of end-exhaled air samples

The analytical approach for determining BTX concentrations in air has been described by Scheepers and coworkers ¹². Briefly, a standard solution of BTX in methanol was used for calibration (CRM47993, Supelco/Sigma‒Aldrich, Zwijndrecht, the Netherlands). Standards were prepared in a range of 0 to 100 ng/µl. Standards (n = 8 in duplicate) and field blanks (n = 2) were loaded on tubes shipped from the Netherlands to Sri Lanka and back to determine if any losses or contamination had occurred during shipment. The ATD tubes were analysed using thermal desorption-gas chromatography‒mass spectrometry (TD-GC‒MS). This system consists of a Unity Ultra autosampler and thermal desorption unit (Markes International, Llantrisant, UK) coupled online to a GC‒MS (Thermo Focus GC and ISQ MS, Thermo Fisher Scientific, Interscience, Breda, the Netherlands). We were not able to separate m- and p-xylene, and hence, the results were reported as m/p-xylene. Exhaled air concentrations were expressed in ng/L by adjustment for the Bio-VOC air volume with a limit of detection (LOD) of 0.1 ng/L.

Assessment of lung function

Spirometry was performed using a Vitalograph Alpha Touch spirometer (Vitalograph Ltd. UK) according to ATS guidelines ¹³ in all study participants. The instrument was calibrated before each test using a 3 L calibration syringe. Disposable bacterial filters were used to prevent cross-infection.

Spirometry was performed from January until August 2018 between 9.00 am and 11.00 am every day to minimise the biological circadian rhythm variations. All spirometry measurements were performed while they were off duty, within two weeks of exposure assessment, in the standing position. The manoeuvre was demonstrated to the patient by a trained investigator. Each manoeuvre was monitored by flow-volume loops and manual observation to ensure that the effort was maximal, smooth and artefact free.

Forced vital capacity (FVC), forced expected volume in the first second (FEV₁), peak expiratory flow (PEF) and forced mid-expiratory flow (FEF25-75%) were recorded. The attempt with the highest recorded measurement was used for analysis. Multiple manoeuvres (up to a maximum of 8) were performed until three satisfactory and reproducible recordings were made. The subjects were asked to rest between manoeuvres.

Repeatability was deemed satisfactory when the difference between the largest and the next largest FVC and FEV₁ was ≤ 0.150 L. The largest FVC and the largest FEV₁ observed from all of the acceptable values were used for analysis. The predicted values were calculated using published reference norms for Sri Lankan Sinhalese males ¹⁴. A restriction was considered clinically relevant when FVC < 80% of predicted and an obstructive ventilatory defect when the FEV₁/FVC ratio < 70% ¹⁵. (Further details are available in Additional file 1).

Statistical analysis

Because the spirometry parameters were normally distributed as confirmed by the Kolmogorov‒Smirnov test (p > 0.05), the arithmetic mean (AM) and standard deviation (SD) were used as descriptive statistics. Nonparametric methods were used for subgroup analysis: a Spearman correlation coefficient was used to study associations between spirometry values and the BTX exposure levels, and the partial correlation coefficient was used to control for the effect of smoking. The Mann‒Whitney U (MWU) statistic was used to compare differences in nonnormally distributed variables. Fisher’s exact test was used to analyse categorical variables between the two groups. A Wilcoxon signed-rank test was used to compare the paired exposure values (at the beginning and the end of the shift) of each individual. Five years of exposure as a gas station attendant was deemed adequate time for structural changes in the respiratory system to be established, and comparisons in duration of exposure by number of years of employment (5 or more years versus less than 5 years). RStudio v3.2.2 was used to determine correlations between spirometry values and the BTX exposure levels.

Complete spirometry tracings were available from 44 gas station attendants and 38 controls. The other participants had difficulty performing the manoeuvres to obtain three reproducible recordings on the day of testing. BTX exposure data were collected from 20 randomly selected gas station attendants and 11 controls.

A significantly higher number of gas station attendants reported waking up with a cough than the controls (p = 0.026) (Table 1). The exposure to fuel in the occupational setting for the gas station attendants per week was 53.14 (15.82) hours per week. Toluene and o-xylene values in the preshift samples of gas station attendants were higher than those in controls (p < 0.001). Postshift values for each of the BTX components separately were also significantly higher among gas station attendants than among controls (p < 0.001) (Table 2).

Table 1

Demographic data and reported respiratory complaints among the cases and controls.
		Gas station attendants (n = 44)	Control (n = 38)	p value¹
Age (years) AM ± SD		39.63 (12.25)	36.42 (11.59)	0.228*
Ethnicity	Sinhala	43 (97%)	36 (94.73%)	0.550
Ethnicity	Other	1 (2.27%)	2 (5.27%)	0.550
Height (cm) AM ± SD		166.00 (6.74)	167.05 (5.26)	0.439
Body weight (kg) AM ± SD		67.78 (14.13)	65.32 (9.26)	0.362
BMI AM ± SD		24.56 (4.51)	23.38 (2.94)	0.172
Smokers		32 (72%)	22 (42.1%)	0.158
Cough		14 (31.81%)	7 (18.42%)	0.189
Shortness of breath (SOB) at rest		5 (11.36%)	2 (5.25%)	0.363
SOB on walking		4 (9.09%)	2 (5.25%)	0.554
SOB during cycling		9 (20.45%)	3 (7.89%)	0.120
Wheezing		12 (27.27%)	8 (21.05%)	0.569
SOB when wheezing		11 (25%)	5 (13.15%)	0.813
Waking up with chest tightness		6 (13.63%)	2 (5.26%)	0.082
Waking up with SOB		3 (6.81%)	2 (5.26%)	0.550
Waking up with a cough		10 (22.72%)	4 (10.52%)	0.026
Persons on treatment for bronchial asthma		3 (6.81%)	3 (7.89%)	0.837

¹ For comparison of categorical data, the chi-square test was used. For continuous data (height, body weight and BMI), a sample t test was used for comparisons.

Table 2

Comparison of median (IQ range) BTX concentrations (ng/L) in end-exhaled air between gas station attendants and controls in ng/L.
Substance	Sample	Exposed (n = 20) Median (IQ range)	p²	Control (n = 11) Median (IQ range)	p²	p³
Benzene	Preshift	11.23 (9.64–16.62)	< 0.0001	9.47 (8.73–11.20)	0.286	0.069
	Post-shift	21.05 (16.28–28.47)	< 0.0001	12.04 (8.78–13.42)	0.286	< 0.001
	Δ¹	7.95 (3.22–13.76)		1.90 (-1.66-5.24)		0.003
Toluene	Preshift	10.39 (8.21–21.16)	0.001	3.13 (2.83–4.93)	0.424	< 0.001
	Post-shift	22.19 (15.32–40.33)	0.001	4.00 (2.62–6.19)	0.424	< 0.001
	Δ¹	11.43 (4.10–17.00)		0.87 (-1.11-1.65)		0.001
m/p-Xylene	Preshift	1.62 (1.34–2.57)	0.002	1.52 (0.91–2.56)	0.091	0.536
	Post-shift	2.45 (1.97–4.22)	0.002	1.25 (1.14–1.56)	0.091	< 0.001
	Δ¹	0.97 (0.36–1.61)		0.64 (-0.45-1.07)		0.338
o-Xylene	Preshift	1.01 (0.82–1.47)	0.010	0.50 (0.34–0.58)	0.859	< 0.001
	Post-shift	1.45 (1.11–2.43)	0.010	0.49 (0.39–0.56)	0.859	< 0.001
	Δ¹	0.54 (0.13-1.00)		0.045 (-0.15-0.08)		0.001

¹Post-shift value minus preshift value; ²Pre-shift vs postshift values in Wilcoxon signed-rank test; ³Gas station attendants vs controls in Mann‒Whitney U test.

Although overall spirometry parameters were lower in gas station attendants, there was no significant difference in the mean spirometry measurements between the two groups except for PEF and % predicted PEF, which were significantly lower among the gas station attendants compared to controls (Table 3).

Table 3

Mean (SD) spirometry values of gas station attendants and controls.
Spirometry	Gas station attendants (n = 44)	Control (n = 38)	Significance¹ (p)
FVC [L]	3.27 (0.69)	3.42 (0.79)	0.346
% predicted FVC [%]	95.8 (13.57)	97.6 (18.55)	0.617
FEV₁ [L]	2.63 (0.60)	2.70 (0.72)	0.646
% predicted FEV₁ [%]	94.3 (12.59)	83.6 (15.62)	0.728
FEV₁/FVC ratio	79.61 (14.58)	92.66 (20.31)	0.676
PEF [L/min]	427.39 (100.41)	488.97 (116.32)	0.012
% predicted PEF	77.5 (17.48)	87.3 (19.38)	0.019
FEF25-75% [L/s]	2.65 (0.94)	2.71 (1.12)	0.827
% predicted FEF25-75%	84.1 (27.79)	80.5(31.55)	0.527
¹ Independent sample t test

Among those who were employed as gas station attendants for less than five years, the mean % predicted FVC (82.71 ± 12.53% vs 91.25 ± 7.50%; MWU = 133.00, p = 0.026) and FEV1 (79.39 ± 13.11% vs 88.31 ± 10.05%; MWU = 134.50, p = 0.029) were significantly higher than those employed for 5 or more years (Fig. 1). However, the mean % predicted FVC was still in the normal range even after 5 years of exposure. Abnormal spirometry patterns (obstruction and restriction) were not significantly more frequent among the group employed for 5 years or more as a gas station attendant compared to those employed less than 5 years (restrictive pattern p = 0.099, obstructive pattern p = 0.355).

In addition to FEV₁ and PEF, the most prominent negative correlations were observed between all of the % predicted lung function parameters except for % predicted FEF 25–75%. (Fig. 2a). Overall, the aforementioned lung function parameters indicate a reduction in lung function, with most expressions of BTX exposure, as indicated by a moderate negative correlation. In the upper part of the heatmap, the pattern is quite scattered (for preshift values), whereas moving down to postshift and delta expressions of BTX indicate a more consistent pattern of moderately to (in some cases) highly negative associations of exposure with lung function. The finding of the highest correlation for delta benzene with % predicted FVC and % predicted FEV₁ suggests that the highest negative correlations with lung function parameters are found for work-related exposure. This may be explained by the divergent kinetics of benzene compared to toluene and xylenes.

The FEV1 ratio and FEF25-75% and % predicted FEF25-75% indicate a less consistent pattern and a tendency toward more positive associations between exposure and lung function. The weak negative and positive associations in Fig. 2 should be interpreted with caution, as these may indicate ‘background noise’. However, the measured lung function parameters remained within the range that is considered ‘normal’.

In contrast to the gas station worker’s heatmap, both positive and negative associations between exposure and lung functions are consistent across the different lung function parameters in the office workers (Fig. 2b). A distinct pattern is shown for both exposure and outcome parameters (Fig. 2a). When comparing the correlations between chemicals, it is clear that postshift and delta benzene are not associated with any of the lung function parameters. Overall, the changes from preshift to postshift for benzene, toluene and m/p-xylene suggest that work-related exposures are not associated with a reduction in lung function.

The pattern for preshift values for BTX except o-xylene suggests a consistent negative association with all lung function parameters. These expressions of exposure are not work-related and might be explained by exposure off-work (e.g., at home or during commuting from home to work and vice versa), including long-term exposure, because the postshift values show a very similar consistent pattern with the exception of benzene and a much weaker and inconsistent effect for o-xylene. O-Xylene is the exception where a consistent negative association with the change from preshift to postshift (as indicated in the analysis by the delta expression) might indicate a link to exposure during work time that remains unexplained due to a lack of information on what controls did during work time did not indicate a source of exposure to o-xylene.

The impact of occupational exposure to BTX on lung function was evaluated by quantitative assessment of exposure to BTX as a health-relevant VOC. Our main finding was that working as a gas station attendant is consistently associated with changes in lung function with a pattern that is distinct from what was observed in office workers. The gas station attendant and control populations were comparable by age, ethnicity, and anthropometric measurements, including BMI and smoking status. The subgroups of workers for whom BTX exposure data were available were comparable (for the same parameters) to the much larger group of workers for whom spirometry was successfully completed.

In the gas station workers, exposure to benzene during work hours (c.f. delta benzene) was observed to be a much more prominent risk factor, whereas in controls, toluene and xylenes appear to be driving lung function changes associated with preshift exposure that could indicate a potential contribution from exposures outside work hours. With the collection of pre- and postshift samples of end-exhaled air, we attempted to determine to what extent BTX exposures are work-related. The rationale for this strategy is the fast kinetics of inhalation and elimination, suggesting that an increase from preshift to postshift suggests exposure occurring during work hours. That this is a reasonable assumption is indicated by the strong correlations observed in gasoline station workers. The pattern of strong correlations within the BTX mixture indicates that exposure occurred from fuels during work hours, whereas the preshift results were clearly correlated less strongly. The high correlations in the postshift and delta results are explained by the common source of all BTX components from primarily fuel vapours and, to some extent, from road vehicles where two-stroke engines of motorcycles are an important source due to incomplete combustion (IARC, 2021). The much weaker correlation with delta benzene may be explained by the 5–10 times higher vapour pressure of benzene compared to toluene and xylenes. This property may affect environmental fate as well as the kinetics of uptake and elimination and explain this deviation. In gas station attendants, a contribution from smoking is unlikely, as smoking is strictly forbidden during work hours.

In our earlier report, BTX was characterised for 29 gas station attendants and 16 controls ¹². In that study, pre- and postshift end-exhaled air was evaluated. BTX concentrations were significantly higher among gas station attendants than among office workers (p < 0.005). In the subgroup with spirometry values in the current analysis (20 gas station attendants and 11 controls), there was a statistically significant increase in VOC levels from pre- to postshift (p < 0.03), signifying an elevated exposure to VOC in this group of gas station attendants.

BTX can be considered both a source of indoor air pollution and outdoor air pollution ¹⁶. Toluene and xylene are also commonly found in household items such as glues, paints and rubber; thus, exposure to these chemical compounds is inevitable. Benzene is primarily observed in combustion sources such as tobacco smoke and solid fuel burning as important indoor sources ¹⁷. Both toluene and xylene exposure have been reported to decrease spirometry values even in residential (nonoccupational) exposures. The site of toxicity is indicated to be both small and large airways, with the mechanism being mediated through oxidative stress-induced damage ¹⁸. That these minute exposures correlate with a reduction in lung function parameters irrespective of lack of direct and prolonged exposure to VOC raises concern.

The correlation matrix indicates a strong correlation of all measured and calculated lung function parameters in controls. In gas station workers, this consistent pattern of interrelationships appears to be disturbed, potentially because of different responses of lung function parameters to BTX exposure and other work-related factors. The reduction in PEF is likely to be attributable to unsatisfactory technique and effort in some attempts and unlikely to be of any significance. The other lung function parameters were not reduced in either group and were not significantly different between gas station workers and controls. Measurement of airway resistance in future studies could reveal more subtle changes in lung function.

Taking together the interrelationships between BTX exposure and lung function parameters, the correlation matrix in the group of gas station attendants was different from that in the control group. The associations observed in both gas station attendants and controls suggest that effects on spirometry parameters are work-related. This is indicated by a consistent moderate negative correlation of % predicted FVC with postshift and delta BTX as an indicator of the development of exposure over a shift. Associations with changes in other lung function parameters are much weaker. The more consistent negative associations with different expressions of lung function decrease with delta benzene exposure (taken as a proxy for exposure occurring during work hours) are remarkable and not observed in controls.

We used the BTX levels in end-exhaled air to correlate with the spirometry findings. Because of the high vapour pressure and poor water solubility, the retention and absorption of BTX are limited. When air concentrations are high, most of these substances have fast kinetics of uptake and elimination via the airways. This results in airways being exposed by BTX entering the lungs and a second time when these substances are eliminated via the airways as the primary route of excretion. The residue leads to a build-up of BTX in the body until a steady state is reached. When the worker is exposed to fresh air, the absorbed parent BTX (if not metabolised in the meantime) leaves the body unchanged via the lungs. This means that both during and after work, the exhaled air contains BTX, and the upper airways will be exposed during both uptake and elimination. This makes exhaled air analysis a useful surrogate measure for airway dose ¹⁹.

If the calculated changes from preshift to postshift within each individual worker (delta) can be used as a proxy for work-related exposures, it is clear that our data do not suggest BTX exposure to be associated with clinically relevant changes in lung function. A remarkable finding is the consistent and strong association of both toluene and m/p-xylene across all expressions of lung function, moderate for preshift and more pronounced for postshift. The lack of a contribution of benzene in this pattern confirms that fuels and traffic exhaust are less likely involved. Exposures to consumer products that contain toluene and xylenes may explain these exposures and their effect on lung function, e.g., the use of paint, glue and decreasing/cleaning agents with a white spirit profile of lightweight aliphatic and aromatic hydrocarbons (white-spirit type) are sources of toluene and xylenes but not benzene. As we have not collected any information on the use of such products in the office environment, we cannot be sure if this exposure can be explained from work or not. As indicated by the strong negative correlation between preshift and postshift values, we can only suggest that it is most likely derived from recent exposure, i.e., the same day.

We hypothesise that the control group was to some extent exposed to BTX outside work hours. This exposure was associated with reduced spirometry values, but to a lesser extent than the group of gas station attendants. This is reflected in somewhat lower correlations of end-exhaled air BTX levels with spirometry values. Although the BTX levels were significantly lower among the controls, even these low exposure levels were negatively correlated with the % predicted FVC. We would expect some of these correlations to become statistically significant in a larger study sample.

To our knowledge, this is the first study to present human biomonitoring by end-exhaled monitoring side by side with spirometry in gas station attendants. A particular strength is the use in this analysis of the increase in end-exhalded air of each of the measured VOC components from preshift to postshift within the same worker as a proxy for work-related exposure. Together with the controls, this indicated the very specific exposure, their profile and specific associations with lung function parameters. Equally important are the exposure measurements included for controls, showing a distinct pattern of the correlation matrix for gas station attendants from controls.

Important limitations in the current study are related to the small sample size due to the low response and spirometry tests not meeting ATS criteria. There was random selection according to the allocation of duty on the days of exposure evaluation and the availability of acceptable spirometry recordings. Members of the research team did not select participants for either investigation based on physical or other characteristics. Only males are employed as gas station attendants in Sri Lanka; hence, we did not include females as controls. Due to the limited availability of study participants, matching gas station attendants with controls by smoking status was not feasible.

We recommend that our findings be reproduced in larger study populations to confirm associations between exposure and health outcome and allow multivariate regression analysis to better adjust for confounders. In future work, female workers should also be included if possible. In the long term, we support moving away from the use of fossil fuels in a transition to more sustainable energy sources for road vehicles. This transition may have a beneficial effect on the health of workers who provide services related to road traffic.

In conclusion, we did not observe changes in lung function of any clinical relevance as a result of exposure to BTX in gas-station attendants or office workers. However, we found that obstructive responses in spirometry were most pronounced for the level of work-related benzene exposure and were also associated with duration of employment. In controls, a distinct pattern of associations of lung function with exposure was observed. We recommend reducing long working hours and installing self-service fuel stations to minimise exposure and related adverse health effects for gas station attendants.

BTX - Benzene, toluene and para, meta and ortho-xylene

ATS - American Thoracic Society

PEF - Peak expiratory flow rate

VOC - Volatile Organic Compounds

CPC - Ceylon Petroleum Corporation

ATD - Analytical Thermal Desorption

FVC - forced vital capacity

FEV₁- Forced Expired Volume in the first second

FEF25-75% - Forced mid-expiratory flow

Ethics approval and consent to participate

Ethical approval was granted by the Ethics Review Committee of the Faculty of Medicine, University of Kelaniya, Sri Lanka (Ref No: P/88/02/2017). All methods were carried out in accordance with relevant guidelines and regulations. Recruitment of participants followed written informed consent. The individual findings of the assessments were made available to each of the participants.

Consent for publication

Not applicable

Availability of data and materials

The datasets generated and/or analysed during the current study are not publicly available as the project is ongoing but are available from the corresponding author on reasonable request.

Competing interests

None of the authors declare competing interests.

Funding

University of Kelaniya research grants: RP/03/04/03/01/2017 and RP/03/04/03/01/2019. The contribution of LdW was supported by the Dutch Occupational Hygiene Society (NvVA).

Authors' contributions

TW, KM, LA, PTJS, and NMD were collaborators in designing and carrying out the research, data analysis and drafting the manuscript. DW, DK, DL, and DDS were the physicians involved in examining the patients and data acquisition and assisted in drafting the manuscript. JA, PR, TD, and SF assisted in spirometry assessment, interpretation of the recordings and preparation of the manuscript. LDW carried out the BTX exposure assessment. DE and RW assisted in data analysis and preparation of the manuscript. All the authors have read and approved the final manuscript.

Acknowledgement

The authors thank the gas station attendants and controls for their participation and their employers for facilitating the study. The authors are grateful to Maurice van Dael and Rob Anzion of the Radboudumc for preparing and supporting the BTX exposure assessment and analysis of end-exhaled air. The authors are thankful to Jos Rooijackers and Bernadette Aalders of The Netherlands Expertise Center for Occupational and Respiratory (NECORD), Utrecht, The Netherlands for fruitful discussion of the lung function data and Ms. Pavani Sandeepani for secretarial assistance.

Authors Information

TW- is a Senior Lecturer in Physiology at the Faculty of Medicine, University of Kelaniya (FOM, UOK) with a special interest in occupational exposures and how they affect the health of humans. She is a Commonwealth Medical fellow trained in autonomic function assessment and has won numerous awards for her research into occupational health.

KM- is a senior lecturer and consultant physician attached to the Department of Physiology at the Faculty of Medicine, University of Kelaniya. He is in charge of the health assessment of persons recruited for studies at the FOM, UOK.

LA- is a Senior Lecturer in Physiology at the Faculty of Medicine, University of Colombo with a special interest in gastrointestinal and respiratory physiology. She is a trainer in Lung Function Testing techniques, trained at the Royal Brompton Hospital as a Commonwealth Academic Fellow. She supervises lung function testing at the Central Chest Clinic, Colombo and the Faculty of Medicine, Colombo. She is a member of the executive committee of the Physiological Society of Sri Lanka and is the outgoing editor. Her research interests include extraesophageal manifestations of gastroesophageal reflux disease and chronic respiratory disorders.

PTJS- is an associate professor at Radboud University and a registered European Registered Toxicologist (ERT) and Occupational Hygienist (RAH). His teaching is focused on human health risk assessment at Radboud University and in postgraduate courses on occupational toxicology and human exposure assessment in postgraduate education in toxicology. He founded the Research Lab Molecular Epidemiology at Radboudumc.

NMD- Is the Head and Chair professor in physiology at the Faculty of Medicine, University of Kelaniya, the immediate past president of the Physiological Society of Sri Lanka (PSSL) and has researched in the field of respiratory disease, although the main interest of research has been gastroenterology.

DW- is a consultant respiratory physician and a senior lecturer attached to the faculty of Medicine, University of Kelaniya. Her main research interests include chronic respiratory diseases and obstructive sleep apnea.

DK- is a consultant endocrinologist and a senior lecturer attached to the faculty of Medicine, University of Kelaniya. Diabetes and osteoporosis are her main research interests.

DL- is a probationary lecturer and trainee in neurology. Her main research interests include Parkinson’s disease and autonomic disorders.

DDS- is a professor in Physiology and is a consultant geneticist attached to the Department of Physiology at the FOM, UOK

JA, PR and TD - Technical officers and research assistants of the Department of Physiology at the FOM, UOK

SF – is a medical graduate who was a research assistant at the time of the study attached to the Department of Physiology at the FOM, UOK. Worked in spirometry assessment, interpretation of the recordings and preparation of the manuscript.

LDW carried out the BTX exposure assessment as part of her master’s thesis in biomedical sciences at Radboud University. She is currently employed at the Netherlands public health service (GGD-GHOR Nederland).

DE- is the Head of the Health Data Science Unit of the FOM, UOK. His research interests include Biostatistics, Health informatics, Spatiotemporal epidemiology.

RW- is the Cadre Chair and Senior Professor and Head of the Department of Public Health, FOM, UOK. His specialisation is Epidemiology and Biostatics.

Sharma AV, Ajmani S. an Analysis of Dynamic Pulmonary Function in Automobile Mechanics. Int J Biomed Res. 2012;3(8):374–7.
Nakai S, Jst C, Nitta H, Maeda K. Respiratory Health Associated with Exposure to Automobile Exhaust. III. Results of a Cross-Sectional Study in 1987, and Repeated Pulmonary Function Tests from 1987 to 1990. Arch Environ Health. 1999;54(1):26–33.
Adeniyi BO. Pulmonary Function and Symptoms Among Petrol Pump Attendents in Nigeria. Int J Biol Med Res. 2014;5(1):3780–4.
Singhal M, Khaliq F, Singhal S, Tandon OP. Pulmonary functions in petrol pump workers: a preliminary study. Indian J Physiol Pharmacol [Internet]. 2007 [cited 2015 Apr 22];51(3):244–8. Available from: file:///C:/Users/soft/Downloads/244–248.pdf.
Warden H, Richardson H, Richardson L, Siemiatycki J, Ho V. Associations between occupational exposure to benzene, toluene and xylene and risk of lung cancer in Montréal. Occup Environ Med. 2018;75(10):696–702.
Begum S, Rathna M. Pulmonary function tests in petrol filling workers in Mysor city. Pak J Physiol [Internet]. 2012 [cited 2016 Dec 21];8(1). Available from: http://www.pps.org.pk/PJP/8-1/Sadiqua.pdf.
Chawla A, Lavania AK. Air pollution and fuel vapour induced changes in lung functions: are fuel handlers safe? Indian J Physiol Pharmacol [Internet]. 2008 Jan [cited 2015 Apr 22];52(3):255–61. Available from: http://www.ncbi.nlm.nih.gov/pubmed/19552056.
Alegretti AP, Thiesen FV, MacIel GP. Analytical method for evaluation of exposure to benzene, toluene, xylene in blood by gas chromatography preceded by solid phase microextraction. J Chromatogr B Anal Technol Biomed Life Sci. 2004;809(1):183–7.
IMF. World Economic Outlook (April 2019) - GDP, current prices. 2018. 2018.
The global economay.com. Sri Lanka Oil consumption - data, chart [Internet]. [cited 2020 Oct 2]. Available from: https://www.theglobaleconomy.com/Sri-Lanka/oil_consumption/.
Department of Motor Traffic H sundaytimes. l. Number of three-wheeled vehicles increases dramatically | The Sunday Times Sri Lanka. 2016. 2016.
Scheepers PTJ, de Werdt L, van Dael M, Anzion R, Vanoirbeek J, Duca RC et al. Assessment of exposure of gas station attendants in Sri Lanka to benzene, toluene and xylenes. Environ Res [Internet]. 2019;178(August):108670. https://doi.org/10.1016/j.envres.2019.108670.
Miller MR, Hankinson J, Brusasco V, Burgos F, Casaburi R, Coates A et al. Standardisation of spirometry [Internet]. Vol. 26, European Respiratory Journal. 2005 [cited 2020 Nov 17]. p. 319–38. Available from: https://erj.ersjournals.com/content/26/2/319.short.
Udupihille M. Spirometric and flow standards for healthy adult non-smoking sri lankans belonging to the sinhalese ethnic group. Ann Hum Biol. 1995;22(4):321–36.
Barreiro TJ, Perillo I. An approach to interpreting spirometry. Am Fam Physician [Internet]. 2004;69(5):1107–14. Available from: http://www.ncbi.nlm.nih.gov/pubmed/15023009.
Scheepers PTJ, Konings J, Demirel G, Gaga EO, Anzion R, Peer PGM et al. Determination of exposure to benzene, toluene and xylenes in Turkish primary school children by analysis of breath and by environmental passive sampling. Sci Total Environ [Internet]. 2010 Sep 15 [cited 2017 Apr 20];408(20):4863–70. Available from: http://www.ncbi.nlm.nih.gov/pubmed/20619876.
Sekar A, Varghese GK, Ravi Varma MK. Analysis of benzene air quality standards, monitoring methods and concentrations in indoor and outdoor environment. Heliyon [Internet]. 2019;5(11):e02918. Available from: https://linkinghub.elsevier.com/retrieve/pii/S2405844019365776.
Yoon HI, Hong YC, Cho SH, Kim H, Kim YH, Sohn JR, et al. Exposure to volatile organic compounds and loss of pulmonary function in the elderly. Eur Respir J. 2010;36(6):1270–6.
Murayama R, Goto S, Nakajima D, Fujimaki H, Watanabe I, Arashidani K, et al. Measurements of exposure concentrations of benzene, toluene and xylene, and amounts of respiratory uptake. J UOEH. 2006;28(2):173–83.

No competing interests reported.

Additionalfile1.docx

Download PDF

Version 1

posted

You are reading this latest preprint version

Association of Lung Function With Benzene, Toluene and Xylene (Btx) in End-exhaled Air in Gas Station Attendants

Status:

Version 1

Abstract

Figures

BACKGROUND

METHOD

Study population

Study area

End-exhaled air sampling

Analysis of end-exhaled air samples

Assessment of lung function

Statistical analysis

RESULTS

DISCUSSION

Abbreviations

Declarations

References

Additional Declarations

Supplementary Files

Status:

Version 1