Imagine working eight hours a day, standing under the scorching sun, inhaling gasoline fumes rising from every vehicle being refueled. For tens of thousands of gas station attendants in Indonesia, this is not a hypothetical scenario—it is their routine. What they may not realize is that every breath can carry benzene, a carcinogenic compound, directly into the cells of their bodies.
A study from the Department of Oral Biology, Faculty of Dentistry, Universitas Gadjah Mada, has revealed something concerning. Prof. Dr. drg. Regina TC. Tandelilin, M.Sc., PBO, and her team found that the frequency of karyorrhexis—the fragmentation of the cell nucleus that serves as a marker of DNA damage—in buccal mucosal epithelial cells of gas station attendants in Sleman Regency was considerably higher than in the control group. The difference was substantial: the average incidence of karyorrhexis among gas station attendants reached 39.93 per 1,000 cells, while the control group had only 10.47 per 1,000 cells.
The Mouth as the First Line of Defense
To understand why this finding is important, it is first necessary to understand the role of the oral mucosa in the human body. The oral cavity is not merely an entry point for food and beverages. It is the first line of defense directly exposed to harmful agents entering through inhalation or ingestion.
Buccal mucosal epithelial cells—the thin layer lining the inside of the cheeks—are non-keratinized, making them much more permeable than other oral tissues such as the gingiva or palate. This means that chemical compounds absorbed through the buccal mucosa can enter systemic circulation directly, bypassing the digestive tract and hepatic metabolism. This makes these cells both a primary target and a sensitive biomarker for detecting genotoxic exposure.
Karyorrhexis itself is one form of nuclear abnormality that occurs when cells enter the apoptosis phase—programmed cell death. The cell nucleus, which should normally remain intact, becomes fragmented, forming a dense, speckled pattern that can be identified under a light microscope. This abnormality is not merely a marker of ordinary cell death; it is a signal that DNA damage is sufficiently severe to trigger the cell death process.
Methodology: A Small Brush, a Major Finding
The study involved 30 male subjects aged 20 to 55 years: 15 gas station attendants who had worked for at least one year at fuel stations in Sleman, and 15 UGM students and staff members serving as the control group, with no history of exposure to gasoline or other genotoxic substances.
Samples were collected using a relatively simple yet precise procedure. Buccal epithelial cells were collected using a cytobrush—a small sterile brush moistened with 0.09% NaCl solution—by rotating the brush at least 360 degrees over the buccal mucosal surface. The exfoliated cells were then smeared onto microscope slides, fixed in 95% ethanol solution, and stained using the Papanicolaou (PAP) method. Each specimen was examined under a light microscope at 1,000× magnification using immersion oil, and at least 1,000 cells were counted per specimen.
The results were analyzed using an independent T-test with a significance level of p < 0.05. The difference found was highly statistically significant, with a p-value of 0.000—far exceeding the established significance threshold.
Benzene, Time, and Accumulating Risk
What strengthens this finding is the consistent pattern: workers who had worked for more than 10 years showed an average karyorrhexis incidence of 45 to 57 per 1,000 cells, while those who had worked for less than 10 years ranged from 31 to 43 per 1,000 cells. The longer the exposure, the greater the damage recorded in their mucosal cells.
Benzene, a major component of gasoline fumes, has long been classified by the International Agency for Research on Cancer (IARC) as a Group 1 carcinogen—the most dangerous category for humans. Reactive benzene metabolites such as phenol, catechol, and hydroquinone can bind to and damage macromolecules, including DNA. This process also triggers the production of reactive oxygen species (ROS), which further aggravate DNA damage. In the long term, repeated exposure to cytotoxic compounds such as these can cause compensatory cell proliferation that may lead to malignant transformation.
Ironically, when the research team conducted field observations, most gas station attendants did not use any personal protective equipment at all—no masks, no gloves. They directly inhaled gasoline fumes every time they filled vehicle tanks. In tropical countries such as Indonesia, this risk may be even higher because gasoline evaporates more readily under high temperature and humidity conditions.
“This study indicates an increased incidence of karyorrhexis in exfoliated buccal mucosal epithelial cells due to repeated exposure to benzene.” — Prof. Dr. drg. Regina TC. Tandelilin, M.Sc., PBO, Department of Oral Biology, FKG UGM
An Early Signal That Must Not Be Ignored
This study is not merely an academic report. It highlights a reality that is often overlooked: occupational health risks in the informal sector—including gas station attendants—are frequently not adequately monitored. There are no regular examinations, no strict protection protocols, and insufficient awareness among workers themselves about the dangers they face every day.
The exfoliative cytology technique used in this study offers a promising solution: it is noninvasive, relatively inexpensive, and sufficiently sensitive to detect cytogenetic changes at an early stage. Buccal mucosal cells can serve as a window into a person’s health long before clinical symptoms appear.
The cell nuclear fragmentation detected under the microscope may appear small and invisible to the naked eye. But for workers who stand every day amid the roar of engines and clouds of gasoline fumes, this small signal could be the earliest—and most valuable—warning they have ever received.
Source DOI: DOI: 10.1016/0027-5107(92)90071-9.
Authors: Anny Anggraini; drg. Achmad Zam Zam Aghasy, M.Kes.
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