Human exposure to polycyclic aromatic hydrocarbons : global cancer risk and metabolism

Graduation date: 2015In recent decades, there has been increased attention on human exposure to, and subsequently toxicity of, Polycyclic Aromatic Hydrocarbons (PAHs). PAHs are widespread organic pollutants and some have been shown to be toxic, carcinogenic and mutagenic. This research was focused on understanding the link between global PAH emissions and lung cancer risk, as well as the metabolism of PAHs by humans. We investigated human exposure to PAHs via inhalation and ingestion, their metabolism to hydroxy-PAHs (OH-PAHs) and compared the results to the OH-PAH concentrations in the general US population.\ud The objective of the first part of this research was to investigate the relationship between lung cancer mortality rates, carcinogenic PAH emissions, and smoking on a global scale. We also investigated this relationship in different socioeconomic country groups. The data from the World Health Organization provided two lung cancer mortality rates, including estimated lung cancer deaths per 100,000 people (ED100000) and age standardized lung cancer death rate per 100,000 people (ASDR100000) for 136 countries. Both mortality rates were regressed on PAH emissions in benzo[a]pyrene equivalence (BaPeq), smoking prevalence, cigarette price, gross domestic product per capita, percentage of people with diabetes, and average body mass index. Both simple linear regression and multiple linear regressions with stepwise procedure were used. The results showed a statistically significant positive linear relationship between log[subscript e](ED100000) and log[subscript e](BaPeq) emissions for high socioeconomic country group (p-value<0.01). Additionally, both log[subscript e](ED100000) and log[subscript e](ASDR100000) were significantly positively correlated with log[subscript e](BaPeq) emissions for the combination of upper middle and high (p-value