چكيده لاتين :
Abstract
Background and aims: Physical and chemical genotoxic factors in the living and working environment cause a variety of DNA damage, including DNA fracture failure, which leads to a variety of mutations that cause various diseases. DNA damage plays an important role in the development of cancer, and most human cancers are associated with DNA instability. DNA biomarkers measuring that cause DNA damage are widely used in molecular and cytogenetic epidemiology to assess the spread of chromosomal damage in human communities exposed to genotoxic agents, as well as to better identify carcinogenic mechanisms.
Exposure to smoke from different fuels leads to damage of DNA and ultimately results to various cancers. Today, the Comte test is one of the standard methods for assessing DNA damage in human screening and molecular epidemiology, caused by lifestyle and environmental and occupational factors, as well as basic research on DNA damage and repair in vitro and in vivo are used. Due to its high sensitivity and ease of use in human studies, the Comte assay was used to measure DNA damage in peripheral blood lymphocytes as a genetic biomarker of cancer risk assessment. Today, the Gas as a suitable, inexpensive and affordable gas for cooking is use as the main fuel in cities. Gas is mainly composed of methane, and its complete combustion reaction results in the production of one carbon dioxide molecule, two water vapor molecules, and heat.
Exposure of the bakeries to high levels of hazardous air pollutants from municipal gas is often forgot. In addition, the exposure of these people in bakeries with different types of baking is not the same. Due to the closed space and improper ventilation of the bakery environment, bakers are in direct and long-term contact with the smoke and vapors emitted from the fuel of the baking machine, these substances enter their bodies through inhalation, skin and eyes, and DNA resulted to cells damaged. The purpose of this study has been to assess the DNA damage in bakery worker lymphocytes according to different baking in compare to control people by using the comet assay.
Methods : In this cross-sectional study, forty-four male baker including 11 people in each of the three groups of different types of Sangaks and Machine and Traditional baking with the same type of gas fuel and 11 controls were studied. The control group was randomly selected from healthy male non-bakers among University of Gonabad staff with no history of baking exposure. Non-bakers’ group was almost similar to the bakers’ group in terms of background variables. The study was approved by the institutional committee of research Ethics (code: 90 / 4 / 395) at Gonabad University of Medical Sciences.
The random sample method was used for sampling. Samples from the list of bakers available in the city's bakers' :union: were randomly selected, and each who had the criteria to enter the study was included in the study. A detailed questionnaire was used to determine the following parameters: socioeconomic and demographic details (age) and personal habits (smoking history, chewing tobacco history, and alcohol-drinking habits), physical characteristics (height in meters and weight in kilograms, which were also used to determine body mass index (BMI); other physical characteristics included systolic pressure and diastolic pressure), and exposure details. Firstly, after obtaining the consent of the selected individuals and completed the demographic profile form, and 5 ml of blood sampling was obtained.
After blood sampling, peripheral blood lymphocytes were isolated from whole blood, and before the comet test, the viability of the cells was determined by trypan blue dye.
The alkaline comet test was used, according to Singh et al.'s method. The cells containing the gel were then prepared. After the gel solidifies, the slides are transferred to a lubricating solution and placed in the dark for 60 minutes. The slides for electrophoresis were then placed in a horizontal electrophoresis tank and the surface-to-surface tank was covered with fresh electrophoresis buffers within 20 minutes. In order to prevent the effect of visible light on naked DNA, all steps were performed in the dark and even the electrophoresis tank was covered with aluminum foil. After electrophoresis, the slides are rinsed and soaked in suitable buffer for 15 minutes. dyed with fixed methanol and 20 mg / mL ethidium bromide (EtBr), for 5 min. The prepared slides were rated with a fluorescent microscope (Nikon 50i) with an x200 magnification.
The slides were evaluated coded and blinded. Two slides were prepared for each sample, and 50 cores per slide, ie 100 cores per sample, and 4400 cores (3300 cores for the study group and 1100 cores for the control group) were examined with Comet Score Version 1.5 software. The DNA damage studied included tail length, percent tail DNA, and tail moment
The Shapiro-Wilk test was used to test the normality of data distribution in each of the three experimental groups and control group. According to the normal distribution of data, one-way analysis of variance to examine quantitative variables age, weight, height, body mass index, blood pressure, work experience, daily working hours, tail length (µm), DNA percentage in tail and tail moment (µm) was used. The p value was considered significant at < 0.05. SPSS software (Version 14, SPSS Inc., Chicago, Illinois, USA) was used for data analysis.
Results :There were not any differences in the size of the room. The air conditioning system was a suitable fan, which was proportional to the size of the room. There was an appropriate chimney, which was proportional to the volume of the oven and was placed one meter above the center of the bakery oven. The results delineated no significant difference between the four groups regarding age, weight, height, BMI, and systolic or diastolic blood pressure. As a result, the groups were homogeneous with regard to these variables (p > 0.05).
The results of this study showed that more than 96 % of isolated lymphocytes are alive and are suitable for further testing. The amounts of DNA damage in the peripheral blood lymphocytes of all bakers were significantly higher than the control group. Most likely, this increase in damage is due to the smoke from the fuel when baking bread indoors and poor ventilation.
Baker in traditional and Sangaks baking trays showed greater damage compared to kind of Machine baking), so that tail lengths (μm) for traditional bakers were 18.70 ± 9.70, 16.33 ± 7.44 (for Sangaks baking), 10.56 ± 6.20 (for Machine baking) versus control group 4.05 ± 1.97. In addition, the percentage of DNA in the tail in the traditional baker group was 3.8 times higher than in the control group (6.70 ± 3/40 versus 1.75 ± 0/79). In the Sangaks and Machine cooking types, although the percentage of DNA in the tail was lower than in the traditional oven-cooking group (5.66 ± 2/16 and 3.72 ± 1/95, respectively), it showed an increase of 3.2 and 2.1 times the damage compared to the control group. In addition, the size of the tail moment was more significant for users of traditional cooking than Sangakss cooking and machine cooking. Furthermore, tail moment size (μm), in traditional baker was higher than other groups, especially control group (4.36 ± 4.00 versus 0.37 ± 0.43, respectively). In addition, tail moment size in sangaks and machine baker were higher than control group (3.45 ± 3.21, 1.52 ± 1.48 versus 0.37 ± 0.43, respectively).
Conclusion : The smoke from fuel used in baking, Because of their mutagenic properties, can lead to increased DNA damage in baker's lymphocytes that was higher in traditional baking type. Furthermore, amount of DNA damage increased by work history increases. It seems higher DNA damage in traditional baker was due to differences in the size of the oven opening and the proximity of the baker to the oven, which causes more smoke to be inhaled from the baker's fuel. Creating awareness among bakers seems to be necessary due to the lack of optimal conditions for fuel and cooking, lack of awareness and, most importantly, incomplete information about conservation processes.
