Peripheral blood lymphocyte subsets in radiologists exposed to ionizing radiation

Exposure to ionizing radiations and changes in blood cells and interleukin-6 in radiation workers

Long-term exposure to ionizing radiation (IR) can cause dire health consequences even less than the dose limits. Previous biomonitoring studies have focused more on complete blood counts (CBCs), with non-coherent results. In this study, we aimed to investigate the association between exposure to IR and cytokine interleukin-6 (IL-6) along with hematological parameters in Tabriz megacity's radiation workers. In this hospital-based study, blood samples were taken from 33 radiation workers (exposed group) and 34 non-radiation workers (control group) in 4 hospitals. Absorbed radiation dose was measured by a personal film badge dosimeter in radiation workers. The studied biomarkers and all of the selected covariates were measured and analyzed using adjusted multiple linear regression models. The exposed doses for all radiation workers were under the dose limits (overall mean = 1.18 mSv/year). However, there was a significant association between exposure to ionizing radiation and IL-6 (49.78 vs 36.17; t = 2.4; p = 0.02) and eosinophils (0.17 vs 0.14; t = 2.02; p = 0.049). The difference between the mean of the other biomarkers in radiation workers was not statistically significant compared to the control group. This study demonstrated that long-term exposure to ionizing radiation, even under the dose limits, is related to a significantly increased level of some blood biomarkers (Il-6 and eosinophil) that, in turn, can cause subsequent health effects such as cancer.

Diminished cellular and humoral immunity in workers occupationally exposed to low levels of ionizing radiation

BACKGROUND

It has been reported that subgroups of T-lymphocytes are affected at different levels and different cell groups of immune system give different responses in individuals exposed to long-term ionizing radiation. The aim of this study was to investigate the effect of occupational exposure to low levels of ionizing radiation in selected indices of cellular and humoral immunity in radiology workers.

METHODS

Level of subgroups of peripheral blood lymphocytes, complements (C(3), C(4)), and total immunoglobulins (IgG, IgA, IgM) were analyzed in 50 radiology workers occupationally exposed to low levels of ionizing radiation and 35 age-matched healthy controls.

RESULTS

CD4(+) T lymphocyte (T-helper) levels were determined as significantly low in radiology workers exposed to ionizing radiation compared with controls (p <0.05). There were no statistically significant differences in groups in terms of other subgroups of lymphocytes (p >0.05). In addition, levels of serum total IgG, IgA, IgM, C(3,) and C(4) were determined as significantly lower in workers exposed to ionizing radiation compared with controls (p <0.001). Total IgA and IgM levels in radiology workers who were smokers were determined as significantly lower compared with non-smoking radiology workers (p >0.05).

CONCLUSIONS

Levels of CD4(+) T lymphocytes and humoral immune response (total immunoglobulins and complements) were determined as weaker in workers exposed to low levels of ionizing radiation compared with controls, indicating the importance of taking appropriate measures to protect radiology workers from exposure to ionizing radiation and for these workers to avoid smoking. Further studies are needed for determining the appropriateness of periodic check-ups of immune functions and the most efficient and cost-effective ways of monitoring immune functions in radiology workers for detecting early changes in the immune system.

Persistent leucocyte abnormalities in children years after previous long-term low-dose radiation exposure

Two hundred and eighty-nine children who had been educated in a kindergarten during 1983-92 and received continuous low-dose whole body gamma-irradiation from 60Co-contaminated steel window frames in their classrooms were investigated for residual effects on their haematological tissues. Another 751 children, sex and age-matched, received similar but much lower exposure in an elementary school with classrooms built with contaminated steel rebars. The peripheral leucocytes of these children were examined 5-7 years after they had stopped using these irradiated classrooms. Children who received higher exposure in the kindergarten were shown to have a significant decrease in total leucocytes and neutrophils and an increase in eosinophils. Moreover, they were shown to be at significantly higher risk of developing relative leucopenia and neutropenia, but not lymphocytopenia, than those who received a lower exposure at the elementary school. Children from the kindergarten who had much higher exposure were shown to have a significant lowering of total leucocytes and neutrophils, and an increase in eosinophils years after exposure. Residual adverse haematological effects on the exposed children are strongly suspected.