Whether Occupational Exposure of Diesel Could Lead to Lung Cancer - Literature review Example

Occupational Exposure to Diesel Exhaust and Lung Cancer Your Name Student Number Edith Cowan University Unit code: Unit Name Tutor: Name of your lecturer/tutor Date Submitted Tittle of Assessment: Occupational Exposure to Diesel Exhaust and Lung Cancer Introduction The purpose of this essay is to review the literature on whether occupational exposure of diesel could lead to lung cancer. The essay will review five articles and provide information on their research objectives, methods, results and conclusions. Each article will be analyzed at a time. Thereafter, the conclusion of this essay will provide a summary of the findings. Occupational exposure refers to exposure to harmful substances at the workplace that may result to harm of a person. Cancer refers to a category of diseases that involve abnormal proliferation and growth of cells with a potential to destroy an organ or cause malfunction that threatens health of a person. Cancerous cells have a potential to spread to other parts of the body. Lung cancer specifically refers to existence of the cancerous cells in the lungs. Literature map LITERATURE REVIEW Cancer has claimed millions of life and its treatment has not been fully discovered and integrated in the healthcare system. Therefore, prevention is the most appropriate approach; however, prevention measures require knowledge on causative factors. The causative factors are diverse as cancer could be triggered by anything. Therefore, research has to be broad based to be able to isolate the specific exposure that influence the likelihood of developing cancer. One such possible risk factor is inhalation of diesel. Many people are exposed to diesel especially the exhaust diesel that could possibly expose them to lung cancer (Krivoshto, Richards, Albertson, & Derlet, 2008; Ridge, McErlean, & Ginsberg, 2013). Case Studies Case-control studies involve use of two sets of groups where one group has the desired characteristic while the other (control group) group does not have the outcome of interest. The following discussion will be about two case studies that evaluated whether occupational exposure to diesel could lead to lung cancer. Olsosson et al (2010) conducted a research on lung cancer among Asphalt workers. A nested case control was conducted in a cohort involving European Asphalt Workers where lung episodes of lung cancer were reported with a possible risk being exposure to bitumen fumes. Four hundred and thirty three cases and 1,253 controls were analyzed after cohorts were done based on the country of origin (e.g. Denmark, Germany etc.) for people who had died of lung cancer between 1980 and 2005. Using the year of birth and country, controls were matched at a ration 3:1. The study found no consistence evidence that exposure to bitumen fume could lead to fume irrespective of the exposure period or the type of bitumen (Olsson et al., 2010). However, a study by Silverman et al. (2012) disputed the above findings in similar case study conducted among diesel miners. The authors had observed that although several studies indicated there was increased risk of lung cancer after exposure to diesel exhaust, no study had developed quantitative data to show the extent of association or risk of exposure. Therefore, they conducted this study with an aim to assess the relationship between diesel exhaust exposure and lung cancer quantitatively (Silverman et al., 2012). A nested case control was conducted whereby 12 315 people from 8 mining facilities that did not involve metals were included. Among them, 198 cases of lung cancer deaths were reported and 562 were sampled control subjects. In every case of lung cancer, four control subjects were selected based on the race, sex, birth year and the mining facility. Diesel exposure was estimated using the elemental carbon exposure as per job and on yearly basis. Thereafter, categorical and continuous regression was carried out at a confidence level of 95% to determine the odds ratio (Silverman et al., 2012). The findings revealed that development of lung cancer was positively associated with exposure to elemental carbon. A cumulative exposure to elemental carbon for fifteen years resulted to positive risk of developing lung cancer. The findings were statistically significant. Those who were exposed to elemental carbon above 105 µg/m3 had 3 times greater risk of developing cancer compared to workers exposed to lower levels of elemental carbon. Hence, the study concluded diesel exhaust exposure contributed to the risk of developing lung cancer (Silverman et al., 2012). Cohort Studies Cohort studies are used in medical research to establish links between the health outcomes and their risk factors. It can be prospective whereby the study participants are actively followed up and investigated or it can be retrogressive whereby the study participants’ history is researched to establish links between exposure and health outcomes. Due to speculations that diesel is carcinogenic, Garshick et al. (2012) aimed to conduct a retrospective study which would help them assess the risk factors associated with lung cancer mortality among truck workers in United States. Records of 31,135 members of the trucking industry workers union were retrieved in 1985 and their work related exposure risk was assessed historically. The lung cancer mortality was assessed up to the year 2000. The research established that the risk of lung cancer was inversely related with the years of employment. However, it was positively correlated to cumulative exposure to elemental carbon. The study concluded that lung cancer increased with increased in exposure to elemental carbon (Garshick et al., 2012). The findings of Garshick et al. (2012) are similar to findings of other studies such as Peters et al. (2016). Peters et al. (2016) assessed the level of exposure to elemental carbon and how it could be related with risk of lung cancer. It assessed the levels of exposure to elemental carbon since 2003 using mixed effect model that targeted five surface and five underground groups. Other aspects that were looked into included the duration of mining as well as the mineral mined. The study revealed that 8614 were exposed to elemental carbon among people who worked in 146 different jobs across 124 mining sites (Peters et al., 2016). The mean estimate of exposure in twelve hours of work was 14µg/m3. Workers in underground jobs had higher exposure levels while the diesel loader who worked underground had the highest exposure of 59µg/m3. Those who worked as lifetime miners (in the surface or underground) were exposed to exposure levels to the maximum of 44 µg/m3 in 2011. Such level of exposure was attributed to between 5.5 and 38 lung cancer deaths per 1000 men. The study concluded that exposure to elemental carbon was substantially high especially for underground workers and the lung cancer that was associated with it required urgent measures to curb the exposure (Peters et al., 2016). However, Bergdahl et al., (2010) recorded a contrary finding. Bergdahl et al. (2010), cohort study was conducted among underground iron ore miners (8321) employed in 1923-1988 and who had exposure to radon. They were followed up from 1958-2000 in addition to assessment of history of exposure to radon, crystalline silica, diesel exhaust and quartz. The results showed that iron ore miners had high risk of developing lung cancer. The cause of the high risk was evaluated. It was established that diesel exhaust and radon were not the possible reason for high risk. Crystalline silica was found to be the major contributor to the high risk of developing lung cancer and quartz was a possible confounding factor (Bergdahl, Jonsson, Eriksson, Damber, & Järvholm, 2010). Critical review of study designs. The case studies conducted were good and appropriate methods of researching lung cancer, which is a relatively rare disease. Besides, the case control approach was appropriate considering that cancer has a long period of latency between exposure and manifestation of the disease. However, the selection bias was the major weaknesses of the case control approach (Yin, 2013). Olsosson et al. (2010), selection of research participants was not random. Certain countries were selected to participate without random sampling and therefore generalization of the findings to the world population would not be feasible. The same happened in Silverman et al. (2012), where 8 mining facilities were selected. Based on the selection bias in the two studies, it was not possible to estimate the incidence of lung cancer among occupations exposed to exhaust diesel. Although cohort studies eliminated the selection bias and were appropriate research methods for long patency disease such as lung cancer, retrospective cohort studies conducted by Garshick et al. (2012) and Peters et al. (2016) did not capture other confounding factors and this could affect the validity of their outcome (Gail, 2000). Conclusion The Case Control by Olsson et al. (2010) could not associate diesel exhaust to risk of lung cancer although Silverman at al. (2012) found quantitative association between exposure to elemental carbon (diesel exhaust) and lung disease. Garshick et al. (2012) recorded similar findings and concluded there was a positive correlation between exposure to diesel exhaust and risk of lung cancer. Peters et al. (2016) improved the previous studies and found that the risk of exposure to elemental carbon (diesel exhaust) was high among underground miners and it predisposed them to a higher risk of developing lung cancer. The purpose of this study was to provide a literature review regarding the association between the risk of lung cancer and exposure to diesel exhaust. Five articles published between 2010 and 2016 were reviewed. Majority of them (4/5) concluded there was a positive association between exposure to diesel exhaust and risk of developing lung cancer. Hence the need for public measures to prevent further exposure and development of lung cancer. References Bergdahl, I. A., Jonsson, H. akan, Eriksson, K. are, Damber, L., & Järvholm, B. (2010). Lung cancer and exposure to quartz and diesel exhaust in Swedish iron ore miners with concurrent exposure to radon. Occupational and Environmental Medicine, 67(8), 513–518. Gail, M. H. (2000). Encyclopedia of Epidemiologic Methods. John Wiley & Sons. Garshick, E., Laden, F., Hart, J. E., Davis, M. E., Eisen, E. A., & Smith, T. J. (2012). Lung cancer and elemental carbon exposure in trucking industry workers. Environmental Health Perspectives, 120(9), 1301. Krivoshto, I. N., Richards, J. R., Albertson, T. E., & Derlet, R. W. (2008). The toxicity of diesel exhaust: implications for primary care. The Journal of the American Board of Family Medicine, 21(1), 55–62. Olsson, A., Kromhout, H., Agostini, M., Hansen, J., Funch Lassen, C., Johansen, C., … others. (2010). A case-control study of lung cancer nested in a cohort of European asphalt workers. Environmental Health Perspectives, 118(10), 1418–1424. Peters, S., Klerk, N. de, Reid, A., Fritschi, L., Musk, A. (Bill), & Vermeulen, R. (2016). Estimation of quantitative levels of diesel exhaust exposure and the health impact in the contemporary Australian mining industry. Occup Environ Med, oemed-2016-103808. https://doi.org/10.1136/oemed-2016-103808 Ridge, C. A., McErlean, A. M., & Ginsberg, M. S. (2013). Epidemiology of lung cancer. In Seminars in interventional radiology (Vol. 30, pp. 093–098). Thieme Medical Publishers. Retrieved from https://www.thieme-connect.com/products/ejournals/html/10.1055/s-0033-1342949 Silverman, D. T., Samanic, C. M., Lubin, J. H., Blair, A. E., Stewart, P. A., Vermeulen, R., … Attfield, M. D. (2012). The Diesel Exhaust in Miners study: a nested case-control study of lung cancer and diesel exhaust. Journal of the National Cancer Institute, 104(11), 855–868. https://doi.org/10.1093/jnci/djs034 Yin, R. K. (2013). Case Study Research: Design and Methods. SAGE Publications. Read More