Effects of exposure to low-dose ionizing radiation on changing platelets: a prospective cohort study

BACKGROUND@#Numerous studies have concentrated on high-dose radiation exposed accidentally or through therapy, and few involve low-dose occupational exposure, to investigate the correlation between low-dose ionizing radiation and changing hematological parameters among medical workers.@*METHODS@#Using a prospective cohort study design, we collected health examination reports and personal dose monitoring data from medical workers and used Poisson regression and restricted cubic spline models to assess the correlation between changing hematological parameters and cumulative radiation dose and determine the dose-response relationship.@*RESULTS@#We observed that changing platelet of 1265 medical workers followed up was statistically different among the cumulative dose groups (P = 0.010). Although the linear trend tested was not statistically significant (P@*CONCLUSION@#We concluded that although the exposure dose was below the limit, medical workers exposed to low-dose ionizing radiation for a short period of time might have increased first and then decreased platelets, and there was a dose-response relationship between the cumulative radiation dose and platelets changing.

The dose-response relationship between low-dose ionizing radiation and thyroid hormone of medical workers / 中国辐射卫生

Objectives To explore the dose-response relationship between low-dose ionizing radiation and thyroid hormone levels of radiation medical workers and provide theoretical basis for occupational health protection to this population. Methods Using a prospective cohort study design, we collected health examination reports on employees that worked on jobs with occupational exposure to radiation at hospital with individually dose monitoring data for 1 237 workers. The effective cumulative radiation dose was divided into three groups: 0～2.586 mSv, 2.586～3.757 mSv, 3.758～31.272 mSv by the interquartile range. The low-dose group was used as a reference to compare the changes in thyroid hormones of medical workers in different cumulative radiation dose groups. The generalized linear models and restricted cubic spline model were used to examine the association and dose-response relationship between the cumulative effective dose and changing thyroid hormones. Results There were statistically significant differences in changing thyroxine (T4) and Free triiodothyronine (FT3) levels among three different dose groups of 1237 subjects (P < 0.05). The results of generalized linear models analysis revealed that 2.586～3.757 mSv was a significant risk factors of changing T4, with β of 3.514 (95% confidence interval [95% CI]: 0.900～6.128) after adjusting for gender, age, working duration, occupation, medical level and smoking, while the association with changing FT3 was not observed (P > 0.05). The restrictive cubic spline (RCS) model analysis indicated a non-linear dose-response correlation between cumulative radiation dose with changing T4 (P = 0.023). Conclusion Long-term exposure to low-dose ionizing radiation could induce the thyroid damage among medical occupational population. And there is a dose-response relationship between cumulative radiation dose and changing thyroxine.

Association of general level of total anti-oxidation capacity, superoxide dismutase, nitric oxide synthase activity in serum with the lifestyle of residents of Bin County of Heilongjiang Province / 中国组织工程研究

BACKGROUND: When the dynamic equilibrium between oxidation system and anti-oxidation system in the body is upset, the overly produced active oxygen-derived free radicals will attack the target organs, thus resulting in the damage to organs and big molecules, and then diseases. Total anti-oxidation capacity (T-AOC), superoxide dismutase (SOD), and nitric oxide synthase (NOS) activity are the majorindexes for the defense system of the body, and their status is closely related to diseases. OBJECTIVE:To explore the level of T-AOC, SOD and NOS in serum,and find out its relationship with lifestyle. DESIGN:Single sample investigation. SETTING:Department of Health Laboratory Technology, College of Public Health of Harbin Medical University. PARTICIPANTS:Totally 531 residents of Bin County aged 20 to 70years were recruited between September 2000 and May2001. MATERIALS:The reagents kits of T-AOC, SOD and NOS were manufactured by Nanjing Jiancheng Bio-engineering Institute. METHODS:The investigators surveyed the residents with the same questionnaire. Questionnaire was made and the investigators were trained in advance. The questionnaire was filled in item by item as required. Questionnaire items consisted of the general situation, financial status, dietary habit, hobby, status of health care, and mental factor. Finally 95 investigation indexes were completed. The activity of serum T-AOC, SOD and NOS of the 531 residents in Bin County was determined, respectively, with reagent kits produced by Nanjing Jiancheng Bio-engineering Institute. The lifestyle factors were analyzed by multivariate stepwise regression analysis,and informed consent was obtained from the participants. MAIN OUTCOME MEASURFS:① Serum T-AOC, SOD and NOS in the participants; ② lifestyle factors affecting T-AOC, SOD and NOS.RFSULTS:According to actual analysis, the 531 participants entered the results analysis. T-AOC was measured in 489 participants, SOD in 525participants, and NOS in 531 participants. ① Indexes of the participants:T-AOC of the males was obviously higher than that of the females [(20.01±7.21), (15.25±6.22) kU/L, P ＜ 0.05]. SOD of the males was slightly lower than that of the females while NOS of the males was slightly higher than that of the females, but there was no significant difference. ②Multivariate stepwise regression analysis showed that risk factors related to T-AOC were gender difference (OR=2.188), educational level (OR=1.859),and the presence of rheumatism, respectively (OR =1.142). SOD-related risk factors were educational level (OR=1.584), years of spirit drinking (OR =1.048), presence of nephritis (OR=1.093), and irradiation (OR=1.770);frequency of tea drinking was a beneficial factor (OR=0.800). NOS-related risk factors were the average amount of cigarette smoking (OR=1.194) and the times of weekly spirit drinking (OR=1.368). However, the beneficial factor that affected serum NOS was the frequency of weekly mutton eating (OR=0.458) CONCLUSION:This experiment revealed that the ability to clean free radical in the 531 subjects was good and that it was better in males than in females. The increased educational level and presence of rheumatism can decrease T-AOC. Drinking, smoking and irradiation decrease SOD activity while the frequency of tea drinking and mutton eating are beneficial factors.