By Shirah Segal
Numerous occupations involve some manageable element of risk or danger, whether physical, chemical or technological. However, according to a review study, “despite all achievements of modern science and technology, working in coal mines remains one of the most dangerous occupations to human health.” Aside from coal, other substances such as graphite, oil, salt, precious metals and gemstones are all substances commonly utilized in our daily lives. These resources are found naturally in underground caves and are extracted through the work of miners.
The mining industry is a core economic activity and is essential for infrastructure development. While highly important, this occupation involves physical danger along with exposure to chemical and biological agents which are detrimental to overall health. Mining also poses an environmental danger to the surrounding communities and ecosystem due to the toxic metals being released. The cytotoxic and genotoxic effects of mining can be assessed using several methods, including the micronucleus assay and the comet assay, both of which detect genetic damage or abnormalities. The micronucleus assay detects the presence of micronuclei, which are extra nuclear bodies that form when chromosomes are not properly distributed during cell division. The comet assay depicts damaged DNA fragments present in a cell as a “comet tail” trailing away from the cell’s nucleus.
In one extensive study done to determine the extent of genotoxic damage in miners, five Colombian coal miners were compared to five control subjects. It has been well established that coal dust contains minerals which can induce oxidative stress and promote DNA damage. The results of three tests performed in the study showed significant levels of difference between the exposed miner group as compared to the unexposed control group. The miner cells displayed high frequencies of chromosomal variations and aberrations, along with significant differences in the amount of micronuclei present. The average number of chromosomal variations and aberrations in the underground miners was fifty times greater than seen in the unexposed control group.
Included in these results was a major increase in the frequency of chromosome and chromatid breaks, which can result in detrimental cell physiology, mutagenesis and cell death. In comparison with the control group, the frequency of micronuclei in miners was almost forty times higher, displaying substantial genetic damage present in underground coal miners. In a similar study conducted on one hundred and fifty eight coal miners in Brazil, blood and buccal samples were subjected to both the comet assay and the micronucleus assay. The results were significant in both, again indicating occupational genotoxic damage to miners.
Coal dust is not the only danger facing miners – the act of mining itself can lead to DNA damage through exposure to toxic metals. In a study conducted in Brazil, twenty two gem miners were compared to seventeen control participants. The gem miners displayed a significantly higher number of abnormalities, indicating genotoxic damage induced by chronic exposure, which can promote cancer cell development.
Another substance commonly mined is Uranium, a known radioactive substance used for nuclear weapons. A DNA fragmentation assay done on leukocytes of uranium mine workers showed a significant increase in fragmented DNA when compared to the control sample. All studies evaluated showed significant evidence of genomic differences as compared to the unexposed participants, indicating genotoxic damage caused by mining.
Mining not only affects the health of the miners, but can also impact the wildlife surrounding the site. In one study which examined the genotoxic effects caused by exposure to uranium wastes, the comet assay was done on European wood mice. The study revealed serious genotoxic effects in organisms which inhabited the contaminated area, including DNA strand breaks and changes in the expression of tumor suppressor genes such as P53. In addition, the micronucleus assay done on fish living in a gold mining area of Colombia revealed significant levels of damage in the exposed fish. In another experiment studying the environmental effects of mining, the comet assay was conducted on exposed caimans living near a gold mine. This test revealed differences in DNA damage levels as well. Earthworms living in contaminated soil near an ore mine in Brazil underwent the comet assay and micronucleus test. Increased DNA damage was observed in the worms, along with a three fold increase in micronuclei as compared to the controls.
Mining activities also negatively impact the health of surrounding communities. In a particularly tragic study, the micronucleus assay was performed on children living near a tungsten mine. The findings revealed a four time increase of genomic abnormalities in children living near the mine. Populations near a mine can also be affected through the presence and use of contaminated soil. In one comet assay conducted on soil near a coal mine, there were high levels of toxic metals present in the dirt, which led to cytotoxic effects. Both an Ames and allium assay done on soil around gem mines in Brazil revealed statistically significant levels of chromosomal abnormalities, including micronuclei, as compared to the negative controls.
While the above studies are alarming, they are noticeably conducted in countries other than America because of U.S. laws and regulations around mining. One example is the Mine Safety and Health Act, which provides miners with safety training, proper equipment and health inspections. There are also companies which exclusively sell “ethical diamonds,” meaning that the mines producing the gems are providing safe working conditions and ensuring environmentally sound practices. Another option which is becoming popular is lab grown diamonds, which do not cause genotoxic damage to miners or the surrounding environment.
As consumers, our choices have power – the next time you purchase gasoline, salt, a ring (diamond or otherwise), or even a lead pencil, take a moment to consider where these materials come from and the impact of their extraction on both people and the planet. Making informed decisions can help support ethical and sustainable practices in industries that often operate out of sight.