Increased Cancer Risk Associated with Radiation in Aerospace

Exposure of long duration to ionizing radiation causes a variety of neoplasms. The most common cases known to occur are malignant melanomas in skin, skin cancers, leukemias and breast carcinomas [1,2]. The Federal Aviation Administration (FAA) has recommended that aircrew members be exposed to no more than 20mSv per year for a 5 years average, with no more than 50mSv in a single year [3,4]. Radiation alters the molecular structure by causing ionization and energizing the molecule. Less energetic radiation, such as visible light, only causes excitation, not ionization, which is usually dissipated as heat with relatively little chemical damage [5-8]. Ultraviolet light is not entirely nonionizing, but produces some ionization and chemical damage. Effects of ultraviolet radiation and ionizing radiation are similar in the causation of cancer and penetrating ionizing radiation hits the molecules randomly [9-11]. Radiation causes production of free radicals by breaking the molecules and causing damage to the chromosomes and genetic rearrangements, translocations and mutations. In this way irreversible cellular damage and chromosomal derangements occur. Major damage normally results in the cell dying or being unable to reproduce with acute effects but these cells cannot cause cancer. The cells which are proliferating and in which the tumor suppressor genes are damaged, they prone to become cancerous. The latest research suggests that mutagenic events do not occur immediately after irradiation. There is phenomenon of microsatellite instability and mismatch repair in the genes which causes mutations in generations and leads to genetic predispositions to cancer. The cell will then progress through multiple stages of neoplastic transformation that may culminate into a tumor after years of incubation. Oncogenesis is due to changes in morphology of cell, uncontrolled proliferation of cells and cellular adaptions to cancer. Prolonged exposure to ultraviolet radiation from the sun can lead to melanoma and other skin cancers which are now supposed to be very common malignancies.