Polycyclic aromatic hydrocarbons (PAHs) are toxic substances that undergo bioaccumulation and can be found in various forms, including coal tar, fossil fuel burning, forest fires, grilling meats over open fires, cigarette smoke, diesel emissions, asphalt surfaces, tar roofs, aluminum and coke plants, and more. PAHs can initiate and promote tumors and may function as complete carcinogens, resulting in a high occurrence of tumors and mortality in laboratory animals. Exposure to PAHs can occur at home, outdoors, or at work, with a mixture of PAHs being more likely. Primary sources of exposure to PAHs include tobacco smoke, wood smoke, inhalation of compounds in ambient air, and consumption of PAHs in foods.
PAH exposure is a significant concern due to its potential to cause cancer. PAH metabolites are absorbed into aquatic environments through various pathways, including atmospheric, municipal wastewater discharges, oil spills, and transportation operations. Exposure to PAHs can lead to lung cancer, scrotal cancer, and other health issues. Occupational exposure to PAHs, such as coal gasification, coke production, and aluminum manufacturing, increases the risk of cancer. Environmental exposure, such as household heating, vehicular traffic, and industrial point sources, contributes to the high cancer risk. PAHs are also absorbed through the gastrointestinal tract and can be metabolized through various pathways. The Toxicity Mechanism is crucial in understanding the carcinogenic and toxic potential of PAHs, as they can form chemical bonds with DNA, leading to mutations, tumors, and cancer.
PAHs have various toxic effects, including hematotoxicity, reproductive and developmental toxicity, immunotoxicity, and carcinogenicity. Excessive exposure to PAHs can lead to lung cancer, urological, gastrointestinal, laryngeal, and pharyngeal malignancies, respiratory effects like cough, chronic bronchitis, and hematuria. Carcinogenic PAHs, such as B[a]P found in cigarette smoke, can cause toxicity and carcinogenesis by interacting with nucleophilic regions of cellular macromolecules, leading to DNA damage in both laboratory animals and humans.
PAHs, especially carcinogenic PAHs, have a significant impact on the development and progression of cancer. They can cause heritable disruptions in gene expression, oxidative stress, inflammation, immunosuppression, receptor-mediated processes, and alteration of cell proliferation through intracellular Ca2+.