Medical staff occupationally exposed to low doses of ionizing radiation. In vivo assessment of the antioxidant‐oxidant status and evaluation of the antioxidant response and oxidative stress after an in vitro blood irradiation

Radiation-induced free radicals are considered to initiate and perpetuate the action of ionizing radiation (IR) on living organisms, causing mutations, cell apoptosis or even genetic instability. Oxidative processes play an important role in the pathogenesis of several diseases (e.g. neurodegenerative and cardiovascular diseases or cancer). In contrast, some authors state that a ‘radiation adaptive response’ can be achieved by low-dose radiation exposure. However, there are reports indicating that workers occupationally exposed to ionizing radiation show increased cancer incidence and DNA breakage, as well as dis-regulated oxidative stress status. Hospital staff working in diagnostic or treatment procedures involving IR represents an important collective exposed to low-dose long-term IR. In this study, the response to chronic low-dose IR exposure of occupational workers was analyzed. For this purpose, the antioxidant-oxidant status of four groups of hospital staff occupationally exposed to IR and a control group was measured as well as the variation of several antioxidant and oxidant markers in response to an in vitro irradiation. The total antioxidant capacity (TEAC), extracellular SOD activity (eccSOD), GSH/GSSG ratio, nitrites and nitrates levels (NOx) and lipid peroxidation (TBARS) were measured in peripheral blood samples of the studied workers. Results showed that the Medicine Nuclear workers were the group in which the exposure to low doses of IR induced the most reduced antioxidant capacity and increased oxidative stress. In contrast, subjects from the Radiation Oncology department had a significant higher antioxidant defense, which gives support to the idea of an adaptive response pointed out by some authors. The results from the in vitro assay