Chemical-Induced Mutagens: Literature Review

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Chemical-Induced Mutagens: Literature Review

            The purpose of this paper is to compare and contrast asbestos and benzene. Asbestos is both a carcinogenic and mutagenic agent; whereas benzene is a carcinogen but not a mutagen. A mutagen causes changes in the genetic material; while, a carcinogen is an agent that can cause cancer in living tissue. The primary route of asbestos exposure is through inhalation of asbestos fibres in air. In some cases, asbestos fibres may be ingested or enter the body through the dermal exposure, when fibers lodge in the skin. Similarly, exposure to benzene can occur through dermal, inhalation, and oral routes. This paper includes search strategy employed for identifying relevant articles, results of the articles, a discussion, and a concluding statement. Both benzene and asbestos can cause life-threatening cancers hence, exposure to any of the chemical represents a serious public health issue.

Search Strategy

            Peer-reviewed journal articles were utilized as sources of evidence in this paper. The selected articles were published not older than seven years from their year of publication (2013-2020).  A monograph by the International Agency for Research on Cancer (IARC) was included as a key authoritative source. Search terms employed included mutagens AND carcinogens, benzene AND carcinogenicity, asbestos AND carcinogenicity OR mutagenicity, and asbestos OR benzene AND disease. Databases that were explored included Business Source Complete, PubMed, EbscoHost, Google Scholar, and Cochrane database. Results of the search are summarized in Table 1 below:

Results of the Literature Search

Table 1: Summary of Research Findings on Asbestos and Benzene

Discussion

            Asbestos and benzene are occupational and environmental hazards. Asbestos are mineral fibers used in manufacture of organic fibers, vitreous, and ceramic (Falzone et al., 2016). Exposure to asbestos can also occur due to contact with asbestos containing products such as ropes, cloth, and blocks (Jadhav & Gawde, 2019). Benzene is an aromatic hydrocarbon that is used in the production of various synthetic fibers, polymers, and resins. Besides, benzene is also a component of tobacco smoke, wood, and gasoline. The population is exposed to benzene through inhalation of vapors, which are released from motor vehicle exhaust gases, cigarette smoke, and service stations. Major exposure to asbestos occurs through inhalation, but can also occur through ingestion of fibres or fibers getting into the body through pricking of skin. Similarly, exposure to benzene may also occur through ingestion of polluted water or food. However, major exposure occurs in industrial settings such as rubber production plants, refineries, shoe manufacturing, printing firms, and factories. Therefore, exposure to benzene can be from the occupational as well as environmental sources (Falzone et al., 2016).

Several studies have pointed out that exposure to asbestos fibers and/or benzene can increase the risk of development of cancers. Asbestos fibers containing fluoro-edenite can induce over expression of fibulin-3 in mesothelial cells. Besides, fluoro-edenite can down-regulate p27, which is a tumor suppressor gene that regulates cell cycle. Benzene is classified as a group 1A carcinogen since it has known toxic effects on the hematopoietic system (Falzone et al., 2016).  IARC (2018) developed significant evidence through animal and human studies that benzene carcinogenic activity is due to the genotoxic effects it causes. It alters oxidative damage on DNA and alters DNA repair mechanism and may cause genomic instability. These may lead to altered cell proliferation, DNA repair, genomic instability, altered nutrient supply, modulation of receptor-mediated effects, and/or cell death (IARC, 2018). Besides, copy number variations and leukemia-associated gene expression might be playing a role in leukemia development in people who are exposed to benzene (Li et al., 2017).

Asbestos can cause cancer of the pulmonary apparatus; especially, development of pleural mesothelioma and lung cancer (Falzone et al., 2016). The incidence of males diagnosed with mesothelioma, who had lived in houses insulated with loose-fill asbestos from Nov 01, 1983 to Dec 31, 2013 were associated with 2.5 times compared to unexposed males. No cases of mesotheliomas were reported among the exposed females. Similarly, exposure to asbestos was also associated with increased incidence prostate cancer in men, colorectal cancer in women (Korda et al., 2015). Asbestos can cause mesothelioma and cancers of the pharynx, larynx, lungs, and ovary. Besides, it can cause the fibrotic lung disease, which is known as asbestosis. It is also known to cause benign fibrous skin lesions and pleural plagues (Jadhav et al., 2019). A study by Im and colleagues (2015) established that asbestos can induce lung cancer. In addition, smoking of cigarettes and asbestos has synergistic effects in inducement of lung cancer (Im et al., 2015).

Benzene can cause chronic disorders such as acute myeloid leukemia, non-Hodgkin’s lymphoma, chronic lymphocytic leukemia, aplastic anemia, and multiple myeloma. It may also induce development of breast cancer, nasal cancer, stomach cancer, prostatic cancer, and malignant melanoma (Falzone et al., 2016).  In addition, benzene causes acute non-lymphocytic leukemia and acute lymphocytic leukemia (IARC, 2018). It has been also established that there is a significant relationship between exposure to asbestos and development of non-Hodgkin lymphoma (Dopart et al., 2019).

Conclusion

Both asbestos and benzene can cause chronic health conditions, especially cancers. Asbestos is considered as a mutagenic as well as a carcinogenic agent, whereas benzene is only a carcinogenic substance but not a mutagenic substance. Individuals can get exposed to asbestos through inhalation, ingestion and perhaps through the skin. Similarly, benzene exposure can occur both in the environment and/or in occupational settings. The route of exposure includes inhalation, ingestion, and absorption through the skin. Asbestos can cause asbestosis, mesotheliomas, cancers of the pharynx, larynx, lungs, and ovary, prostate cancer in males, and colorectal cancer in females. Benzene can cause chronic disorders such as acute myeloid leukemia, non-Hodgkin’s lymphoma, chronic lymphocytic leukemia, aplastic anemia, and multiple myeloma.