Benzene, toluene, ethylbenzene, and xylene: Current analytical techniques and approaches for biological monitoring

Abstract

Benzene, toluene, ethylbenzene, and xylene (BTEX) are a group of volatile organic compounds that human exposure to them may result in the development of some diseases, including cancer. Biological monitoring plays an important role in exposure assessment of workers occupationally exposed to chemicals. Several metabolites have been proposed for biological monitoring of individuals who are exposed to BTEX. There are a variety of extraction methods and analytical techniques for the determination of unmetabolized BTEX in exhaled air and their urinary metabolites. The present study aimed to summarize and review the toxicokinetics of BTEX and sample preparation and analytical methods for their measurement. Metabolites of BTEX are discussed to find out reliable ones for biological monitoring of workers exposed to these chemicals. In addition, analytical methods for unmetabolized BTEX in exhaled air and their metabolites were reviewed in order to obtain a comparison between them in term of selectivity, sensitivity, simplicity, time, environmental-friendly and cost. Given the recent trends in sample preparation, including miniaturization, automation, high-throughput performance, and on-line coupling with analytical instrument, it seems that microextraction techniques, especially microextraction by packed sorbents are the methods of choice for the determination of the BTEX metabolites.

Biomarkers after Controlled Inhalation Exposure to Exhaust from Hydrogenated Vegetable Oil (HVO)

“…BTEX are formed from combustion processes and smoking, but they are also omnipresent contaminants of indoor air [ 17 , 32 , 33 ]. Air concentrations of BTEX in our exposures were low, with maximal concentrations of 8 µg/m 3 BTEX during the HVO PM+NOx exposure ( Table S1 ), and thus similar to air concentrations measured in North American (0.27−4.9 µg/m 3 ) and European countries (0.02−26 µg/m 3 ) [ 17 ].…”

Prospects and Challenges of MXenes as Emerging Sensing Materials for Flexible and Wearable Breath‐Based Biomarker Diagnosis

“…Xylene excretes unchanged in the exhaled breath. [131] Xylene isomers have a similar distribution in the human body, mainly distributed in well-suffused organs such as the liver and kidney. [132] Para-xylene was correlated with prostate cancer and, therefore, a potential biomarker candidate.…”

Analysis of 10 urinary BTEX metabolites using LC–MS/MS

“…In one of the studies (Chiang et al, 2015) the measured concentration of The urine samples were collected in the morning regardless of any previous job-related activity. Because the urinary BTEX metabolites have half-lives of up to 25 h (Soleimani, 2020), their presence in urine can mark only recent exposure. BTEX are ubiquitous in the modern environment; therefore, their metabolites are present in the urine of the general population to a certain extent depending on lifestyle (Li et al, 2021).…”

“…The secondary metabolites have elimination half‐lives of hours and are nonvolatile. Most of the metabolites are specific to the parent compounds (Table 1); that is, combining with noninvasive urine sample collection makes them suitable biomarkers of occupational and environmental exposure to BTEX (Soleimani, 2020). BTEX metabolites being organic acids are good candidates for LC–MS/MS analysis; thus, various analytical methods have been published for their monitoring in urine (Alwis et al, 2012; Belal et al, 2019; Oh et al, 2017).…”

“…Benzene, toluene, ethylbenzene and xylenes are ubiquitous volatile organic compounds (VOC) known as BTEX (Soleimani, 2020). The term 'xylenes' describes three isomers in which the position of two methyl groups varies on the benzene ring.…”