Blood BTEX levels and neurologic symptoms in Gulf states residents

Association of urinary volatile organic compounds and chronic kidney disease in patients with diabetes: real-world evidence from the NHANES

BACKGROUND

Chronic kidney disease (CKD) is common in patients with diabetes mellitus (DM). Volatile organic compounds (VOCs) are widespread pollutants that may impact DM development.

OBJECTIVE

This study aims to explore the association between urinary VOC metabolites and CKD in patients with DM.

METHODS

Adult National Health and Nutrition Examination Survey (NHANES) 2011 to 2018 participants with DM were included in this study. CKD was defined as an estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2 or urine albumin-to-creatinine ratio (UACR) ≥ 30 mg/g. Multivariable regression models were used to analyze the associations between urinary VOC metabolites and CKD.

RESULTS

A total of 1,295 participants with DM and a mean age of 59 years were included. After adjustment for demographic and clinical characteristics, elevated levels of N-acetyl-S-(2-carbamoylethyl)-L-cysteine (AAMA) (tertile 2: adjusted odds ratio (aOR)  =   1.81, 95% confidence interval (CI): 1.15-2.85, p  =  0.012), N-acetyl-S-(N-methylcarbamoyl)-L-cysteine (AMCC) (tertile 2: aOR   =  1.84, 95% CI: 1.10-3.08, p  =  0.021), DHBMA (tertile 3: aOR  =  1.93, 95% CI: 1.12-3.35, p  =   0.020), and phenylglyoxylic acid (PGA) (tertile 3: aOR   =  1.71, 95% CI: 1.11-2.63, p  =  0.017) were significantly associated with increased likelihood of CKD.

CONCLUSION

Specific urinary VOC metabolite levels are positively associated with an increased risk of CKD in patients with DM. These findings suggest that monitoring urinary VOC metabolites could be important for the prevention and management of CKD in this population. Future longitudinal studies should focus on establishing causality and elucidating the underlying mechanisms of these associations.

Health effects of air pollutant mixtures (volatile organic compounds, particulate matter, sulfur and nitrogen oxides) - a review of the literature

The health risks associated with individual air pollutant exposures have been studied and documented, but in real-life, the population is exposed to a multitude of different substances, designated as mixtures. A body of literature on air pollutants indicated that the next step in air pollution research is investigating pollutant mixtures and their potential impacts on health, as a risk assessment of individual air pollutants may actually underestimate the overall risks. This review aims to synthesize the health effects related to air pollutant mixtures containing selected pollutants such as: volatile organic compounds, particulate matter, sulfur and nitrogen oxides. For this review, the PubMed database was used to search for articles published within the last decade, and we included studies assessing the associations between air pollutant mixtures and health effects. The literature search was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A number of 110 studies were included in the review from which data on pollutant mixtures, health effects, methods used, and primary results were extracted. Our review emphasized that there are a relatively small number of studies addressing the health effects of air pollutants as mixtures and there is a gap in knowledge regarding the health effects associated with these mixtures. Studying the health effects of air pollutant mixtures is challenging due to the complexity of components that mixtures may contain, and the possible interactions these different components may have.

Temporal Variation and Industry-Specific Differences of the Use of Volatile Organic Compounds from 2018 to 2023 and Their Health Risks in a Typical Industrially Concentrated Area in South China

The risk of occupational exposure to organic solvents varies across industries due to factors such as processing materials, ventilation conditions, and exposure duration. Given the dynamic nature of organic solvent use and occupational exposures, continuous monitoring and analysis are essential for identifying high-risk hazards and developing targeted prevention strategies. Therefore, this study aims to analyze the use of organic solvents and volatile organic compounds (VOCs) in different industries in Bao'an District, Shenzhen, China, from 2018 to 2023, to understand their temporal variation and industry-specific differences and to identify high-risk occupational hazards. This study includes 1335 organic solvent samples, used by 414 different industry enterprises, and 1554 air samples. The result shows that the usage of organic solvents in various industries decreased with the outbreak of the pandemic and, conversely, increased as the situation improved. The most frequently detected volatile components in organic solvents were alkanes, followed by aromatic hydrocarbons. The ratios of the detection frequency of VOCs to the total number of detected categories increased year by year after 2020, indicating a tendency towards reduction and concentration of the types of organic solvents used in industrial production. Among the 8 high-risk VOCs, toluene (22.5%), n-hexane (22.0%), xylene (16.1%), and ethylbenzene (15.3%) have relatively high detection rates, suggesting that they need to be focused on in occupational health. Through air samples, the results show that trichloroethylene and xylene pose a high risk to human health (HQ > 1). We recommend that industry should strengthen monitoring of these two VOCs.

A review of disrupted biological response associated with volatile organic compound exposure: Insight into identification of biomarkers

Volatile organic compounds (VOCs) are widespread harmful atmospheric pollutants, which have long been concerned and elucidated to be one of the risks of acute and chronic diseases for human, such as leukemia and cancer. Although numerous scientific studies have documented the potential adverse outcomes caused by VOC exposure, the mechanisms which biological response pathways of these VOC disruption remain poorly understood. Therefore, the identification of biochemical markers associated with metabolism, health effects and diseases orientation can be an effective means of screening biological targets for VOC exposure, which provide evidences to the toxicity assessment of compounds. The current review aims to understand the mechanisms underlying VOCs-elicited adverse outcomes by charactering various types of biomarkers. VOCs-related biomarkers from three aspects were summarized through in vitro, animal and epidemiological studies. i) Unmetabolized and metabolized VOC biomarkers in human samples for assessing exposure characteristics in different communities; ii) Adverse endpoint effects related biomarkers, mainly including (anti)oxidative stress, inflammation response and DNA damage; iii) Omics-based molecular biomarkers alteration in gene, protein, lipid and metabolite aspects associated with biological signaling pathway disorders response to VOC exposure. Further research, advanced machine learning and bioinformation approaches combined with experimental results are urgently needed to ascertain the selection of biomarkers and further illuminate toxic mechanisms of VOC exposure. Finally, VOCs-induced disease causes can be predicted with proven results.

Association between volatile organic compounds and serum neurofilament light chain in US adults

OBJECTIVE

This study aimed to investigate the associations between exposure to blood volatile organic compounds (VOCs) and the level of serum neurofilament light chain (NfL) in adults.

METHODS

We analyzed data from the 2013-2014 National Health and Nutrition Examination Survey (NHANES), including 2008 participants aged 20 to 75 years old. Multiple linear regression models were used to examine the associations between 28 VOCs and NfL after adjusting for multiple potential confounders. Restricted cubic spline (RCS) was used to examine the potential non-linear associations.

RESULTS

The linear regression models showed that higher levels of 2,5-dimethylfuran (β = 0.042, 95 % confidence interval [CI]: 0.001, 0.096), ethyl acetate (β = 0.118, 95 % CI = 0.008, 0.304), and m-/p-xylene (β = 0.043, 95%CI = 0.012, 0.074) were associated with higher NfL levels. These estimates were largely consistent after adjusting for multiple confounders.

CONCLUSION

The findings of our study suggest a potential association between certain volatile organic compounds (2,5-dimethylfuran, ethyl acetate, and m-/p-xylene) and blood NfL levels, implying that they may have a role in revealing neurodegeneration and influencing neurological health.

Association between urinary BTEX metabolites and dyslexic odds among school-aged children

Benzene, toluene, ethylbenzene, and xylene (BTEX) are ubiquitous in the environment, and all of them can cause neurotoxicity. However, the association between BTEX exposure and dyslexia, a disorder with language network-related regions in left hemisphere affected, remains unclear. We aimed to assess the relationship between BTEX exposure and dyslexic odds among school-aged children. A case-control study, including 355 dyslexics and 390 controls from three cities in China, was conducted. Six BTEX metabolites were measured in their urine samples. Logistic regression model was used to explore the association between the BTEX metabolites and the dyslexic odds. Urinary trans,trans-muconic acid (MU: a metabolite of benzene) was significantly associated with an increased dyslexic odds [odds ratio (OR) = 1.23, 95% confidence interval (CI): 1.01, 1.50], and the adjusted OR of the dyslexic odds in the third tertile was 1.72 (95% CI: 1.06, 2.77) compared to that in the lowest tertile regarding urinary MU concentration. Furthermore, the association between urinary MU level and the dyslexic odds was more pronounced among children from low-income families based on stratified analyses. Urinary metabolite levels of toluene, ethylbenzene, and xylene were not found to be associated with the dyslexic odds. In summary, elevated MU concentrations may be associated with an increased dyslexic odds. We should take measures to reduce MU related exposure among children, particularly those with low family income.

Exposure to BTEX is associated with cardiovascular disease, dyslipidemia and leukocytosis in national US population

BACKGROUND

Comprehensive research on the effects of individual benzene, toluene, ethylbenzene, and xylenes (BTEX) and their mixture measured in blood samples, on cardiovascular diseases (CVD) and related risk factors among the general population is limited.

OBJECTIVES

To investigate the effects of blood individual and mixed BTEX on total CVD and its subtypes, lipid profiles, and white blood cell (WBC) count.

METHODS

Survey-weighted multivariate logistic regression was used to examine the associations between blood individual and mixed BTEX with CVD and its subtypes in 17,007 participants from NHANES 1999-2018. The combined effect of BTEX mixture on CVD was estimated using weighted quantile sum modeling and quantile g-computation. Weighted multivariate linear regression assessed the effects of BTEX on lipid profiles and WBC, including its five-part differential count.

RESULTS

In comparison to the reference quartile of BTEX mixture, individuals in the highest quartile had a significantly increased adjusted odds ratio of CVD risk (1.64, 95 % CI: 1.23 to 2.19, P for trend = 0.008). Positive associations were observed for benzene, toluene, ethylbenzene, and m-/p-xylene, demonstrating a monotonically increasing exposure-response relationship. Mixed BTEX was associated with congestive heart failure (CHF), angina pectoris, and heart attack. Individual benzene, toluene, and ethylbenzene were associated with CHF, while toluene, ethylbenzene, and all xylene isomers were linked to angina pectoris. Benzene, toluene, and o-xylene were associated with heart attack. Both mixed and individual BTEX showed positive associations with triglycerides, cholesterol, low-density lipoprotein, and WBC, including its five-part differential count, but a negative relationship with high-density lipoprotein. Subgroup analyses identified modifying effects of smoking, drinking, exercise, BMI, hypertension, and diabetes on the associations between specific toxicants and CVD risk.

CONCLUSIONS

Exposure to BTEX was associated with cardiovascular diseases and cardiovascular risk factors. These findings emphasize the importance of considering blood BTEX levels when assessing cardiovascular health risks.

Long-term effects of the Hebei Spirit oil spill on the prevalence and incidence of allergic disorders

The Hebei Spirit oil spill accident occurred in December 2007, approximately 10 km off the coast of Taean, South Korea, a location notably close to residential areas. Crude oil substances have been detected in various environmental mediums since the accident, yet previous studies have primarily focused on the acute effects of oil exposure due to the short latency period of allergic diseases. Therefore, this study evaluated the long-term effects of oil spill exposure on allergic disorders. Our study included adult residents who had participated in the Health Effects Research on Hebei Spirit Oil Spill (HEROS) study up to five years post-incident, which was a prospective cohort to monitor the health status of Taean residents. We used two indicators to assess oil spill exposure, namely the distance from the initial contaminated coastline to each participant's residence and the number of days participants had engaged in oil clean-up work. Current symptoms such as asthma, allergic rhinitis, atopic dermatitis, allergic conjunctivitis, and multimorbidity were considered allergic disorders. In the baseline survey, the prevalence of asthma, allergic rhinitis, atopic dermatitis, allergic conjunctivitis, and allergic multimorbidity symptoms was associated with both exposure indicators; however, these associations were not observed in the two consecutive surveys. Significant longitudinal associations between oil spill exposure indicators and the four allergic disorders, as well as multimorbidity incidences, were observed during a five-year follow-up period. Our results suggest that oil spill exposure can affect acute and long-term allergic symptoms in residents near the accident site.

Association between ambient BTEX mixture and neurological hospitalizations: A multicity time-series study in Taiwan

BACKGROUND

Benzene, toluene, ethylbenzene, and xylenes, collectively known as BTEX, are hazardous chemical mixtures, and their neurological health effects have not been thoroughly evaluated. We examined the association between BTEX exposure and neurological hospital admissions.

METHODS

This was a multicity time-series study conducted in five major Taiwanese cities. Daily hospital admission records for diseases of the nervous system from January 1, 2016, to December 31, 2017, were collected from the National Health Insurance Research Database. Ambient BTEX and criteria pollutant concentrations and weather factors were collected from Photochemical Assessment Monitoring Stations. We applied a Poisson generalized additive model (GAM) and weighted quantile sum regression to calculate city-specific effect estimates for BTEX and conducted a random-effects meta-analysis to pool estimates.

RESULTS

We recorded 68 neurological hospitalizations per day during the study period. The daily mean BTEX mixture concentrations were 22.5 µg/m3, ranging from 18.3 µg/m3 in Kaohsiung to 27.0 µg/m3 in Taichung, and toluene (13.6 µg/m3) and xylene (5.8 µg/m3) were the dominant chemicals. Neurological hospitalizations increased by an average of 1.6 % (95 % CI: 0.6-2.6 %) for every interquartile range (15.8 µg/m3) increase in BTEX at lag 0 estimated using a GAM model. A quartile increase in the weighted sum of BTEX exposure was associated with a 1.7 % (95 % CI: 0.6-2.8 %) increase in daily neurological hospitalizations.

CONCLUSION

We found consistent acute adverse effects of BTEX on neurological hospitalizations in Taiwan, with toluene and xylene as the dominant chemicals. These findings aid the development of more targeted public health interventions.

Comparison of acetylcholinesterase among employees based on job positions and personal protective equipment in fuel station

The purpose of this study was to compare the levels of acetylcholinesterase (AChE) among employees based on job positions and the wearing of personal protective equipment (PPE) in fuel station areas. The sample group consisted of 200 people sorted into various groups, including (i) Inside fuel dispenser area (I-FDA) group consisting of 100 employees for refueling, cashier, and loading fuel into storage tanks, and (ii) Outside fuel dispenser area (O-FDA) group, consisting of 100 employees working in convenience stores, food stores, coffee shops, and offices, as well as general staff and car washers. Data were collected using interview questionnaires and blood samples were analyzed for AChE activity. The results showed that the I-FDA group had a significantly lower mean of serum AChE (7.38±1.73 U/ml) than the O-FDA group (7.85±1.49 U/ml) (p<0.05). The I-FDA group had a 2.43 times higher risk of abnormal serum AChE than the O-FDA group (OR=2.43, 95%CI=1.05-5.60). When considering the risk factors for job positions, it was found that refueling and cashier positions had lower AChE activity levels than those who did not (p<0.05). In the part, employees for food sales in a closed building and those wearing PPE masks had significantly higher AChE activity levels than those who did not or who wore them (p<0.05). Based on the aforementioned, employers at fuel stations should strictly determine the appropriate measures for wearing a PPE mask. Further, employees should be provided accommodation away from oil supply or enclosed buildings during breaks to reduce the effects on the neurotransmitter.

Exposure to volatile hydrocarbons and neurologic function among oil spill workers up to 6 years after the Deepwater Horizon disaster

BACKGROUND

During the 2010 Deepwater Horizon (DWH) disaster, oil spill response and cleanup (OSRC) workers were exposed to toxic volatile components of crude oil. Few studies have examined exposure to individual volatile hydrocarbon chemicals below occupational exposure limits in relation to neurologic function among OSRC workers.

OBJECTIVES

To investigate the association of several spill-related chemicals (benzene, toluene, ethylbenzene, xylene, n-hexane, i.e., BTEX-H) and total petroleum hydrocarbons (THC) with neurologic function among DWH spill workers enrolled in the Gulf Long-term Follow-up Study.

METHODS

Cumulative exposure to THC and BTEX-H across the oil spill cleanup period were estimated using a job-exposure matrix that linked air measurement data to detailed self-reported DWH OSRC work histories. We ascertained quantitative neurologic function data via a comprehensive test battery at a clinical examination that occurred 4-6 years after the DWH disaster. We used multivariable linear regression and modified Poisson regression to evaluate relationships of exposures (quartiles (Q)) with 4 neurologic function measures. We examined modification of the associations by age at enrollment (<50 vs. ≥50 years).

RESULTS

We did not find evidence of adverse neurologic effects from crude oil exposures among the overall study population. However, among workers ≥50 years of age, several individual chemical exposures were associated with poorer vibrotactile acuity of the great toe, with statistically significant effects observed in Q3 or Q4 of exposures (range of log mean difference in Q4 across exposures: 0.13-0.26 μm). We also observed suggestive adverse associations among those ≥ age 50 years for tests of postural stability and single-leg stance, although most effect estimates did not reach thresholds of statistical significance (p < 0.05).

CONCLUSIONS

Higher exposures to volatile components of crude oil were associated with modest deficits in neurologic function among OSRC workers who were age 50 years or older at study enrollment.

Blood Concentrations of Volatile Organic Compounds Among US Workers From Various Trades

OBJECTIVE

This study aimed to examine blood benzene, toluene, ethylbenzene, o-xylene, and m-/p-xylene (BTEX) concentrations and their trends contrasting construction workers with workers in other occupations from 1999 to 2014 in the United States. Methods: Using data from the National Health and Nutrition Examination Survey, quantile regressions were performed to investigate associations between occupation and blood BTEX concentrations. Results: We found that high-risk and construction occupations were associated with increased blood concentrations of toluene, o-xylene, and m-/p-xylene at the 50-90th percentiles (P 50-90 ), and ethylbenzene at P 70-90 . Moreover, although blood concentrations of ethylbenzene, o-xylene, and m-/p-xylene trended down among all US workers, no decreasing trend was observed for benzene and toluene among construction workers. Conclusions: Future studies are warranted to address questions about specific tasks to better assess VOC exposure from various trades.

Benchmark dose estimation based on oxidative damage in Chinese workers exposed to benzene series compounds

This study evaluated the effects of BTEX exposure on oxidative stress; it analyzed the correlation between oxidative stress and peripheral blood counts and estimated the benchmark dose (BMD) of BTEX compounds. This study recruited 247 exposed workers and 256 controls; physical examination data were collected and serum oxidative stress levels were measured. Relationships between BTEX exposure and biomarkers were analyzed using Mann-Whitney U, generalized linear model, and chi-square trend tests. Environmental Protection Agency Benchmark Dose Software was used to calculate the BMD and lower confidence limit of the BMD (BMDL) for BTEX exposure. The total antioxidant capacity (T-AOC) correlated positively with peripheral blood counts, and negatively with the cumulative exposure dose. On using T-AOC as the outcome variable, the estimated BMD and BMDL for BTEX exposure were 3.57 mg/m³ and 2.20 mg/m³, respectively. Based on T-AOC, the calculated occupational exposure limit of BTEX was 0.055 mg/m³.

Risk of longer-term neurological conditions in the Deepwater Horizon Oil Spill Coast Guard Cohort Study - Five years of follow-up

BACKGROUND

Long-term neurological health risks associated with oil spill cleanup exposures are largely unknown. We aimed to investigate risks of longer-term neurological conditions among U.S. Coast Guard (USCG) responders to the 2010 Deepwater Horizon (DWH) oil spill.

METHODS

We used data from active duty members of the DWH Oil Spill Coast Guard Cohort Study (N=45224). Self-reported oil spill exposures were ascertained from post-deployment surveys. Incident neurological outcomes were classified using International Classification of Diseases, 9th Revision, codes from military health encounter records up to 5.5 years post-DWH. We used Cox Proportional Hazards regression to calculate adjusted hazard ratios (aHR) and 95% confidence intervals (CI) for various incident neurological diagnoses (2010-2015). Oil spill responder (n=5964) vs. non-responder (n= 39260) comparisons were adjusted for age, sex, and race, while within-responder comparisons were additionally adjusted for smoking.

RESULTS

Compared to those not responding to the spill, spill responders had reduced risks for headache (aHR=0.84, 95% CI: 0.74-0.96), syncope and collapse (aHR=0.74, 95% CI: 0.56-0.97), and disturbance of skin sensation (aHR=0.81, 95% CI: 0.68-0.96). Responders reporting ever (n=1068) vs. never (n=2424) crude oil inhalation exposure were at increased risk for several individual and grouped outcomes related to headaches and migraines (aHR range: 1.39-1.83). Crude oil inhalation exposure was also associated with elevated risks for an inflammatory nerve condition, mononeuritis of upper limb and mononeuritis multiplex (aHR=1.71, 95% CI: 1.04-2.83), and tinnitus (aHR=1.91, 95% CI: 1.23-2.96), a condition defined by ringing in one or both ears. Risk estimates for those neurological conditions were higher in magnitude among responders reporting exposure to both crude oil and oil dispersants than among those reporting crude oil only.

CONCLUSION

In this large study of active duty USCG responders to the DWH disaster, self-reported spill cleanup exposures were associated with elevated risks for longer-term neurological conditions.

Biomonitoring of BTEX in primary school children exposed to hookah smoke

Hookah smoking is one of the major indoor sources of benzene, toluene, ethylbenzene, and xylenes (BTEX). This study aimed to investigate the potential exposure to BTEX among primary school children, particularly those exposed to hookah smoke. This cross-sectional study was conducted in Khesht, one of the southwestern cities in Iran, in mid-June 2020. Totally, 50 primary school children exposed to hookah smoke were chosen as the case group and 50 primary school children were selected as the control group. Urinary un-metabolized BTEX was measured by a headspace gas chromatography mass spectrometry (GC-MS). Additionally, a detailed questionnaire was used to gather data and information from the students' parents. The mean levels of urinary benzene, toluene, ethylbenzene, m,p-xylene, and o-xylene were 1.44, 5.87, 2.49, 6.93, and 7.17 μg/L, respectively in the exposed children. Urinary BTEX was 3.93-folds higher in the case group than in the controls (p<0.05). Household cleaning products, the floor on which the house was located, children's sleeping place, and playing outdoors were found to be important factors in predicting urinary BTEX levels. Overall, it was found necessary to avoid indoor smoking to prevent the emission of BTEX compounds via exhaled mainstream smoke and to protect vulnerable non-smokers, especially children, from exposure to second-hand and third-hand smoke.

Factors affecting prevalence of neurological symptoms among workers at gasoline stations in Rayong Province, Thailand

This cross-sectional study was aimed at assessing the exposure to organic solvents and the factors affecting prevalence of neurological symptoms among workers at gas stations in Rayong Province. The sample included 200 workers at gas stations, including refueling staff, cashiers, food shop, coffee shop, and convenience store employees. Interview questionnaire included general information, work history, and neurological symptoms. Urine collection devices were used to detect organic solvents metabolized in urine, including t,t-muconic acid (t,t-MA), hippulic acid (HA), mandelic acid (MA), and methylhppuric acid (MHA).The results showed that the workers' medians (interquartile range: IQR) of the metabolized organic solvents were as follows: t,t-MA was 393.62 (244.59) µg/g Cr, HA was 0.32 (0.14) g/g Cr, MA was 0.06 (0.02) g/g Cr, and MHA was 0.40 (0.13) g/g Cr. For prevalence of neurological symptoms, top three symptoms were headache (49.0%), dizziness (42.5%), and stress/irritability (38.5%). Working at a gas station present was neurological symptoms more than in the past was 32.5%. According to the assessment of exposure to metabolized organic solvents and factors affecting the prevalence of neurological symptoms, overtime work ≥ 6 hours and HA content greater than quartiles Q3 had an effect on neurologic symptoms (OR=2.17; 95%CI=1.23-5.10 and OR=2.15; 95%CI=1.18- 4.76, respectively). In summary, time spent working in gas stations and exposure to toluene organic solvents can cause neurological symptoms. It is recommended to reduce overtime or add breaks during work shifts or shift changes. In addition, workers should be away from the solvent.

A novel preclinical model of environment-like combined benzene, toluene, ethylbenzene, and xylenes (BTEX) exposure: Behavioral and neurochemical findings

Environmental exposure to toxicants is a major health issue and a leading risk factor for premature mortality worldwide, including environmental exposures to volatile organic compounds (VOCs), specifically Benzene, Toluene, Ethylbenzene, and Xylene (BTEX). While exposure to these compounds individually has shown behavioral and neurochemical effects, this investigation examined the impact of exposure to combined BTEX using a preclinical model. Male Swiss Webster mice were exposed to BTEX vapors designed to approximate environmental levels in urban communities. Animals were exposed to one of four treatment conditions: a 0-ppm (air control), two BTEX groups representing levels of environmental-like exposure, and a fourth group modeling occupational-like exposure. These exposures were conducted in 1.5-h sessions, 2 sessions/day, 5 days/week, for 3 weeks. Effects on coordination (i.e., rotarod and inverted screen test), learning and memory (i.e., Y-maze), and locomotor behavior (i.e., movement during exposure) were assessed during and after exposure. Monoamine levels in the medial prefrontal cortex and nucleus accumbens were assessed immediately following exposure. Effects of BTEX exposure were found on the variance of locomotor activity but not in other behavioral or neurochemical assessments. These results indicate that the combination of inhaled BTEX at environmentally representative concentrations has demonstrable, albeit subtle, effects on behavior.

Advances in pretreatment and analysis methods of aromatic hydrocarbons in soil

Benzene compounds that are prevalent in the soil as organic pollutants mainly include BTEX (benzene, toluene, ethylbenzene, and three xylene isomers) and PAHs (polycyclic aromatic hydrocarbons). These pose a severe threat to many aspects of human health. Therefore, the accurate measurement of BTEX and PAHs concentrations in the soil is of great importance. The samples for analysis of BTEX and PAHs need to be suitable for the various detection methods after pretreatment, which include Soxhlet extraction, ultrasonic extraction, solid-phase microextraction, supercritical extraction, and needle trap. The detection techniques mainly consist of gas chromatography (GC), mass spectrometry (MS), and online sensors, and provide comprehensive information on contaminants in the soil. Their performance is evaluated in terms of sensitivity, selectivity, and recovery. Recently, there has been rapid progress in the pretreatment and analysis methods for the quantitative and qualitative analyses of BTEX and PAHs. Therefore, it is necessary to produce a timely and in-depth review of the emerging pretreatment and analysis methods, which is unfortunately absent from the recent literature. In this work, state-of-art extraction techniques and analytical methods have been summarized for the determination of BTEX and PAHs in soil, with a particular focus on the potential and limitations of the respective methods for different aromatic hydrocarbons. Accordingly, the paper will describe the basic methodological knowledge, as well as the recent advancement of pretreatment and analysis methods for samples containing BTEX and PAHs.

Effects of inhaled combined Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX): Toward an environmental exposure model

Combined environmental exposures to the volatile organic compounds (VOCs) Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) pose clear risks to public health. Research into these risks is under-studied even as BTEX levels in the atmosphere are predicted to rise. This review focuses on the available literature using single- and combined-BTEX component inhaled solvent exposures in animal models, necessarily also drawing on findings from models of inhalant abuse and occupational exposures. Health effects of these exposures are discussed for multiple organ systems, but with particular attention on neurobehavioral outcomes such as locomotor activity, impulsivity, learning, and psychopharmacological responses. It is clear that animal models have significant differences in the concentrations, durations and patterns of exposure. Experimental evidence of the deleterious health and neurobehavioral consequences of exposures to the individual components of BTEX were found, but these effects were typically assessed using concentrations and exposure patterns not characteristic of environmental exposure. Future studies with animal models designed appropriately to explore combined BTEX will be necessary and advantageous to discovering health outcomes and more subtle neurobehavioral impacts of long-term environmental exposures.

Blood BTEXS and heavy metal levels are associated with liver injury and systemic inflammation in Gulf states residents

INTRODUCTION

Exposures to volatile organic compounds and metals have previously been associated with liver diseases including steatohepatitis, although more data are needed. Benzene, toluene, ethylbenzene, xylenes, styrene (BTEXS) and metals were measured in blood samples collected between May 2012-July 2013 from volunteers participating in home visits for the Gulf Long-term Follow-up (GuLF) Study. This cross-sectional analysis evaluates associations of exposure biomarkers with serum liver injury and adipocytokine biomarkers in a sample of 214 men.

METHODS

Adult nonsmoking men without a history of liver disease or heavy alcohol consumption were included. The serologic disease biomarkers evaluated were the hepatocellular injury biomarker, cytokeratin 18 [whole (CK18 M65) and caspase-cleaved fragment (CK18 M30)]; and adipocytokines. Confounder-adjusted beta coefficients were determined using linear regression models for the overall sample (primary endpoints) and for obesity-classified sub-groups (secondary endpoints). A product interaction term between the exposure of interest and a dichotomized indicator of obesity was included to determine the disease modifying effects of obesity on the biomarker associations.

RESULTS

The study sample was 57% white and 51% obese. In the overall sample, lead was positively associated with CK18 M30 (β = 21.7 ± 6.0 (SE), p = 0.0004); IL-1β (β = 32.8 ± 5.2, p < 0.0001); IL-6 (β = 72.8 ± 18.3, p = 0.0001); and IL-8 (β = 140.8 ± 42.2, p = 0.001). Cadmium exposures were associated with increased IL-1β (β = 77.8 ± 26.3, p = 0.003) and IL-8 (β = 419.5 ± 201.2, p = 0.04). There were multiple significant interactions between obesity and exposure to lead, cadmium, benzene and toluene in relation to outcome biomarkers. Among obese participants (n = 108), benzene, lead, and cadmium were each positively associated with CK18 M30, IL-1β, IL-6, and IL-8. In obese subjects, lead was also inversely associated with leptin, and toluene was positively associated with IL-1β.

CONCLUSION

For the overall sample, heavy metal exposures were associated with liver injury (lead only) and/or systemic inflammation (lead and cadmium). Obesity modified the associations between BTEXS and heavy metal exposures on several of the outcome variables. In the obesity subgroup, liver injury was positively associated with lead, cadmium and benzene exposures; systemic inflammation was increased with lead, cadmium, benzene, and toluene exposures; and leptin was inversely associated with lead exposures. The cross-sectional design of this study makes it difficult to determine causality, and all results should be interpreted cautiously. Nonetheless, the potential impact of exposures to lead, cadmium, benzene and toluene in steatohepatitis, an obesity-associated inflammatory liver disease, warrants further investigation.