DNA Damage and Repair Detected by The Comet Assay in Lymphocytes of African Petrol Attendants: A Pilot Study

Abstract

Petrol attendants are exposed to petrol volatile organic compounds (VOCs) which may have genotoxic and carcinogenic effects. The single-cell gel electrophoresis assay (comet assay) is a method highly sensitive to DNA damage induced by environmental and occupational exposure to carcinogenic and mutagenic agents. The aim of this study was to evaluate the level of exposure of petrol attendants to petrol VOCs and also to determine their effect on DNA damage and repair in lymphocytes of African petrol attendants. The exposed group consisted of 20 subjects, randomly selected from three petrol stations. A control group of 20 unexposed subjects was also chosen and matched for age and smoking habits with the exposed group. Sorbent tubes were used to assess personal exposure of petrol attendants. The comet assay was used to investigate the basal DNA damage and repair capacity in isolated lymphocytes of petrol attendants and unexposed subjects. Blood samples were taken from the petrol attendants at the end of their 8-h working shift and also from the unexposed subjects. The petrol attendants were found to be exposed to levels of petrol VOCs lower than the South African occupational exposure limit for constituent chemicals. A significant relationship was found between the volume of petrol sold during the shift and the average concentrations of benzene, toluene and the total VOCs measured. However, relative humidity had a negative correlation with the average concentrations of benzene, toluene, xylene and the total VOCs. Significantly higher basal DNA damage was observed with the exposed group compared to the unexposed group. The period of exposure influenced the level of DNA damage and the calculated repair capacity. Smoking and age had a significant influence on the level of DNA damage. DNA repair capacity was delayed in smokers of both exposed and unexposed group.

Health Risk Assessment of Ambient Air Concentrations of Benzene, Toluene and Xylene (BTX) in Service Station Environments

“…Each reference provided one or more sets of individual BTX measurements, with each set representing measurements for a sampling location, activity or job description. A number of data sets were available where only mean concentration were reported [2,7,24,25,32,33,34,35,36,37,38,39,40,41,42]. These were not included in the risk assessment exposure analysis.…”

“…Personal air samples were collected using air sampling pumps worn by the attendants during their work shift. The data sets used in this scenario were obtained from the following references and had the means and standard deviations for benzene (B), toluene (T) and xylene (X) as indicated: [3], B (910 ± 140); T (1580 ± 180); X (890 ± 110); [4], B (4 ± 1); T (241 ± 118); X (240 ± 122); [7], B (650 ± 470); T (730 ± 410); X (310 ± 160); [13], B (1081 ± 491); T (2180 ± 1100); X (1940 ± 2060).…”

“…Short term human exposures to relatively high concentrations of benzene can give rise to various adverse health effects such as headaches, dizziness, inability to concentrate, impaired short term memory and tremors [20]. While long term exposures can give rise to more complex health effects that include haematotoxicity, genotoxicity, immunological and reproductive effects as well as various cancers [7,17]. …”

“…Various studies have shown chronic exposures to benzene with service station attendants may result in the occurrence of cancer and other adverse health effects [24]. In a similar study, DNA damage was observed with service station attendants exposed to benzene [7]. Many studies on BTX exposure in service stations have been conducted and are summarized in Table 1.…”

Occupational Exposure Estimate of Benzene and the Effectiveness of Control Measure in Gabon’s Gasoline Storage and Distribution Facility

“…Short term high exposures to benzene on human can give rise to various adverse effects such as headaches, dizziness, inability to concentrate, impaired short term memory and tremors [6,7] and is considered as acute exposure effects. While long term human exposure can give rise to more complex health effects including haematotoxicity, genetoxicity, immunological and reproductive effects as well as various cancers [8] and is considered as chronic exposure effects. In general, acute exposure effects are considered to be reversible, while chronic exposure effects are probably irreversible [9].…”