By: Sima Zucker
Growing up in New Jersey, I took gas attendants for granted, especially once I learned how to drive. Most states in the country require self-service at gas stations, but I didn’t know that until I moved to New York City. Most of us try to avoid the unpleasant fumes at gas stations by making our stops at gas stations as quick as possible. But did you ever wonder about the dangerous chemical exposures to gas station workers and those living near a fuel distribution center?
Analyzing chromosomal aberrations in cells is a universal method for determining genotoxic risks. When the frequency of chromosomal aberration in the cells of gas attendants was tested, there was a higher percentage of damaged DNA compared to the experimental group of gas attendants. In Barcelona, a study compared 50 gas-filling workers working at 11 different stations and a control group of 43 healthy university students. The Mann-Whitney U-test was used to compare urinary metabolites of the subjects. There was no significant difference in the average number of micronuclei in the gas station workers. Higher levels of hippuric acid and phenol were found in the urine of gas station workers.
Benzene is carcinogenic and its main modes of human transmission are smoking and gasoline. A study was done in Brazil to test the levels of benzene that gas attendants are exposed to. The study compared the levels of benzene in 179 gas-filling attendants, 90 gas station convenience store workers and 100 office workers. The levels of benzene in the workers were measured by using UV detection to test the amount of trans,trans-Muconic Acid (ttMA) in the urine. The results showed that the convenience store workers had the highest levels of t,t-MA: an average of 0.221 mg/g creatinine. Next, the gas-filling attendants had the second to highest levels: an average of 0.195 mg/g creatinine. The average level of the office workers control group was significantly lower than the rest: 0.126 mg/g creatinine. This experiment clearly shows the biological dangers for gas station workers.
In a study of 40 gas station attendants and a group of 40 control subjects, a variety of basal, differentiated, karyolytic, condensed chromatin, karyorrhectic, pyknotic, binucleated, micronucleated, and nuclear bud cells were analyzed. They found a significant increase in micronuclei and nuclear buds amongst the gas attendants. The results showed an increase in chromosomal instability, DNA damage, and cell-cycle abnormalities in the experimental group. This experiment supports the carcinogenic concerns for gas station attendants. Benzene causes breaks in the DNA strands, topoisomerase II, defects to the mitotic spindle and chromosomal translocations. With these defects, aneuploidy occurs more frequently and has the potential to cause leukemia.
To determine the correlation of male infertility with occupational exposure to petrol, diesel and kerosene, a study was carried out by exposing mice to varying concentrations of the given chemicals. In a sperm abnormality assay, the sperm were analyzed after 35 days of exposure. There was an increase in frequency of abnormally shaped sperm cells amongst the mice who were exposed to the poisonous leachate. Some of the interesting shapes included amorphous head, knobbed hook, double tail, and banana-shaped sperm. The low sperm quality indicates a low-quality DNA in the participating mice. Oddly shaped sperm heads are usually due to a mutagen, a change in the DNA. The most frequent sperm abnormality was the amorphous head which was strongly associated with petrol and kerosene. Regarding the sperm count, the mean sperm count per epididymis declined significantly (p<0.05) in the negative control. Both the sperm quality and count decreased in the mice, both contributing factors to lower levels of fertility. High exposure to the given chemicals increased the frequency of genetic damage in both somatic and germ cells. Benzene exposure affects the levels of testosterone in the blood, which can lead to male hormonal imbalance and infertility.
Sister chromatid exchanges, DNA cross linking agents, DNA adduct formations, and impairment of DNA repair mechanisms are different types of DNA damage caused by the potent chemical, benzene. The DNA of two female Brazilian gas attendants who had experienced benzene poisoning was studied. Only 3 pairs of chromosomes were studied: 1, 2, and 4. Complex chromosomal rearrangements (CCR) were identified with fluorescence in situ hybridization. For example, it showed chromosome 2 was slightly folded over. A decrease of natural killer cells was found with a mutant gene CD16 expression. When a person does not have enough natural killer cells, the body doesn’t detect viruses and illnesses as efficiently; the immune system is weakened. Additionally, excessive exposure to benzene caused early pregnancy loss in both women. More research has shown that the chromosomal abnormalities caused by benzene negatively affect one’s ability to produce healthy children.
When looking for a more efficient source of fuel, it was proposed that methanol should be used as an alternative method of fuel. They performed an experiment to determine the genotoxic effects of methanol. Instead of ethanol alone, the gas attendants were exposed to a combination of fuel: 30% methanol, 60% ethanol, and 7% gasoline. An interesting result was the apparent coloration between the wives of gas attendants having miscarriages. The scientists suggested that the methanol caused damage to the germ cells.
Mitochondrial DNA lacks protective histones and does not repair as efficiently as nuclear DNA. The relative mitochondrial DNA copy number (MtDNAcn) was studied in an experimental group [gas station workers] and a control group [unexposed]. It was observed that the gas station workers had a significantly higher mean concentration (0.74) in comparison to the control group (0.67). This study shows that mitochondrial DNA is more susceptible to mutations than nuclear DNA. The mitochondrial DNA in the sperm does not enter the egg. All the mitochondrial DNA in a fetus is exclusively from the egg. Therefore, abnormalities in the female mitochondrial DNA can negatively affect female fertility.
More mutations caused by benzene and other potent chemicals in fuel are continuously being discovered as genetic research becomes more accessible. For all the mutations that are known, there are so many more that are not yet discovered. When occupational exposure of a specific chemical is confirmed to cause cancers, infertility or any other dangers, government regulations are put in place to limit hazards. However, government regulations don’t protect you completely; just like we do not know all the dangers, neither does the government.