Dosimetry associated with exposure to non-ionizing radiation: very low frequency to microwaves

The interpretation of the effects in biological systems exposed to electromagnetic (EM) fields requires knowledge of the internal fields and absorbed energy. The quantification of the specific absorption rate (SAR) is called dosimetry. The SAR given in units of watts per kilogram is a complex function of the source configuration, shape and size of the exposed subjects, orientation of the subject with respect to the source, and the frequency. The average and maximum SAR in the exposed subject may vary over many orders of magnitude for a given exposure level. In order to relate observed biological effects in exposed laboratory animals to safe exposure levels for man, both the fields within the environment and SAR within the exposed tissues must be determined. The environmental fields and the SAR can often be determined from EM theory, but in most cases one must rely on instrumentation such as field survey meters for quantifying the exposure fields and electric field probes, thermocouples, thermistors, fiber optic probes, thermography, and calorimetry for quantifying the SAR in the tissues or equivalent models. A combination of techniques, each valid for a particular model over a particular frequency range, have been used to determine average and peak SARs in humans and animals exposed to plane wave radiation. Though it has been considerably more difficult to quantify these quantities for near field and partial-body exposure conditions, progress is continually being made in this area.     

Prenatal radiation exposure: background material for counseling pregnant patients following exposure to radiation

Fetal sensitivity to radiation-induced health effects is related to gestational age, and it is highly dependent on fetal dose. Typical fetal doses from diagnostic radiology are usually below any level of concern. Although rare, significant fetal radiation doses can result from interventional medical exposures (fluoroscopically guided techniques), radiation therapy, or radiological or nuclear incidents, including terrorism. The potential health effects from these large radiation doses (possibly large enough to result in acute radiation syndrome in the expectant mother) include growth retardation, malformations, impaired brain function, and neoplasia. If exposure occurs during blastogenesis (and the embryo survives), there is a low risk for congenital abnormalities. (In all stages of gestation, radiation-induced noncancer health effects have not been reported for fetal doses below about 0.05 Gy [5 rad].) The additional risk for childhood cancer from prenatal radiation exposure is about 12% per Gy (0.12%/rad) above the background incidence.     

职业性慢性放射性皮肤损伤病例分析

对我院近20年来诊治的22例职业性慢性放射性皮肤损伤病例进行总结分析。结果显示,22例均为男性,放射诊断医师2人,骨科医师20人,放射作业工龄6～46年,估算手部累积吸收剂量为39.1～233.7 Gy,确诊为慢性放射性皮肤损伤Ⅰ度1例,Ⅱ度6例,Ⅲ度15例,皮肤损伤Ⅲ度合并放射性皮肤癌5例。提示慢性放射性皮肤损伤有一定的潜伏期,存在剂量-效应关系。长期不愈的放射性溃疡或角质增生物是皮肤癌变的基础。     

Childhood leukemia incidence and exposure to indoor radon, terrestrial and cosmic gamma radiation

This study was undertaken to evaluate the ecological association between terrestrial and cosmic gamma radiation, indoor radon, and acute leukemia incidence among children under 15 y of age. From 1990 to 2001, 5,330 cases of acute leukemia were registered by the French National Registry of Childhood Leukemia and Lymphoma. Exposure to terrestrial gamma radiation was based on measurements, using thermoluminescent dosimeters, at about 1,000 sites covering all the "Départements." In addition, 8,737 indoor terrestrial gamma dose rate measurements covering 62% of the "Départements" and 13,240 indoor radon concentration measurements covering all the "Départements" were made during a national campaign. Cosmic ray doses were estimated in each of the 36,363 "Communes" of France. There was no evidence of an ecological association between terrestrial gamma dose (range: 0.22-0.90 mSv y) or total gamma dose (range: 0.49-1.28 mSv y) and childhood acute leukemia incidence, for acute myeloid leukemia (AML) or for acute lymphoblastic leukemia (ALL), in univariate or multivariate regression analyses including indoor radon. A significant positive association between indoor radon (range: 22-262 Bq m) and AML incidence among children was observed and remained significant in multivariate regression analyses including either terrestrial gamma dose [SIR per 100 Bq m = 1.29 (1.09-1.53)] or total gamma dose [SIR per 100 Bq m = 1.29 (1.09-1.53)]. The study showed no ecological association between terrestrial gamma radiation and childhood leukemia for the range of variation in gamma dose rates observed in France. The moderate ecological association between childhood AML incidence and indoor radon does not appear to be confounded by terrestrial gamma dose.     

低剂量辐射暴露人群血细胞分析参数变化的影响因素分析

目的探讨LDREP血红蛋白浓度、红细胞计数、单核细胞百分比、淋巴细胞百分比、未成熟粒细胞数和高荧光强度细胞数等血细胞分析报告参数和研究参数受LDR影响的主要因素。方法采用单因素方差分析发现工种和接触射线类型对上述6个因变量的影响,采用多元线性回归分析发现年龄、执业年限和年剂量当量对上述6个因变量的影响,并构建和检验方程。结果男性淋巴细胞百分比主要受工种和年剂量当量的影响,未成熟粒细胞数主要受工种和接触射线类型的影响,高荧光强度细胞数主要的影响因素是工种和年剂量当量;女性血红蛋白浓度主要受接触射线类型因素的影响,红细胞计数受年剂量当量的影响,单核细胞百分比和淋巴细胞百分比主要受执业年限的影响。结论血细胞分析指标中有部分指标与接触电离辐射的计量存在相关性和线性关系应当进一步研究。     

职业性外照射个人剂量监测中本底值选择的探讨

目的 探讨个人剂量监测中医院不同科室本底值的差异情况。方法 按不同职业类别对医院科室进行分组,并布放跟随本底剂量计,将测得的本底值分别与机关办公室对照本底值进行比较分析。结果 该医院本底剂量水平在0.22~0.33 mSv范围,机关办公室的3个布点办公书柜、办公桌抽屉、办公桌面本底值分别是（0.28±0.02） mSv、（0.28±0.01） mSv、（0.31±0.01） mSv;与机关办公室本底值相比,普放1层、口腔科、放疗中心1层、导管室1层均大于机关办公室（P<0.05）,CT区、PET-CT控制室、神经外科、实验室均小于机关办公室（P<0.05）,心内科与机关办公室没有统计学差异（P>0.05）。结论 不能使用单一本底值作为一种个职业分类或一个单位的本底值,应对每个科室布放跟随本底剂量计来降低本底值结果的误差。     

Effects of exposure to very high frequency radiofrequency radiation on six antenna engineers in two separate incidents

Six men are likely to have been accidentally exposed to high levels of very high frequency (VHF) radiofrequency radiation (100 MHz) while working on transmission masts; four men in one incident and two in another. They experienced symptoms and signs which included headache, parasthesiae, diarrhoea, malaise and lassitude. The condition of four men, two men from each incident likely to have had the highest exposure, has shown no significant improvement. The first incident occurred in 1995 and the second in 1996.     

低剂量长期砷暴露对HaCat细胞周期及周期蛋白影响

目的探讨低剂量长期砷暴露对人皮肤角质形成细胞系HaCat细胞周期及周期蛋白D1(cyclin D1)和p21影响。方法HaCat细胞暴露于浓度为0、0.05、0.1 μmol/L的NaAsO₂ 15周后,用流式细胞仪测定10 000个细胞的细胞周期分布;用western blot法检测细胞cyclin D1和p21的蛋白表达水平。结果与对照组比较,NaAsO₂染毒组细胞的G₀/G₁期细胞数明显增高,S期细胞数明显降低,而G₂/M期无明显变化;0.05、0.1 μmol/L砷染毒组细胞内cyclin D1表达水平分别为(152.40±8.17)%、(145.59±2.89)%,与对照组[(99.99±1.13)%]比较,均明显增高;0.05、0.1 μmol/L砷染毒组细胞内p21表达水平分别为(64.06±1.62)%、(39.57±1.82)%,均明显低于对照组的(99.9±2.83)%,呈剂量效应关系(P<0.05)。结论长期低剂量砷暴露可诱导HaCat细胞周期异常,cyclin D1表达上升,p21表达下降。     

Assessment of non-sinusoidal, pulsed, or intermittent exposure to low frequency electric and magnetic fields

The correct assessment of non-sinusoidal, pulsed, or intermittent exposure to low frequency electric and magnetic fields already is a key issue in the occupational environment while becoming more and more important in the domain of the general public. The method presented provides a simple and safe solution for the assessment of arbitrary field types--including sinusoidal and continuous-wave signals--with frequencies up to several 100 kHz and has already proven its practicability and usefulness for more than 5 years. The concept is based on fundamental laws of physics and electrostimulation and well-established physiological data. It allows for a seamless and easy integration in any standard or guideline dealing with human safety in electric, magnetic, and electromagnetic fields. A very simple-to-use graphical version allows an easy and fast assessment of the exposure to non-sinusoidal, pulsed, or intermittent low-frequency magnetic fields without introducing a large overestimation of the exposure situation. A computer-based version makes a much more detailed signal analysis possible and can provide useful information for exposure reduction using modifications of the magnetic field's time parameters (e.g., rise/fall times).     

Ovarian damage to Channa punctatus after chronic exposure to low concentrations of Elsan, mercury, and ammonia

Histopathological changes were induced in the ovary by chronic nonlethal levels of Elsan (211 ppb), mercury (16.7 ppb), and ammonia (15.64 ppm). In the breeding season, treated Channa punctatus revealed a significant decrease in ovarian weight throughout the duration of the experiment. Acute changes were noted in the diameter and percentage occurrence of the different stages of oocytes. In all cases, stage I oocytes revealed no difference in diameter with respect to control although they demonstrated an increase in the percentage occurrence. For stages II and III, a remarkable decrease occurred in both the number and the diameter of these mature oocytes. The preponderance of stage I and destruction of stage II and stage III oocytes in all three treatments indicate that chemically diverse xenobiotics have equal reproductive toxicity in fish, interfering with their breeding.     

Biological and biochemical effects of chronic exposure to very low levels of dietary cypermethrin (Cymbush) on honeybee colonies (Hymenoptera: Apidae)

Cymbush (100 g of pure cypermethrin/liter of petroleum ether) was added to sucrose syrup at 12.5 microg/L and given to honeybee colonies (Apis mellifera mellifera, L.) in their diet for 5 months (July to November). Many perturbations have been recorded in treated groups in contrast to controls placed in the same area. Mortality in the hive, bee behavior, brood areas, supersedure, glucosemia, trehalosemia, and (Na+,K+)ATPase activity are many factors significantly affected over the 18-week test following sublethal treatment. Results suggested that long-term exposure of honeybees to cypermethrin-contaminated diets at concentrations not immediately lethal to worker adults may cause significant hidden damage to colonies.     

低剂量射线长期暴露对人群健康影响

目的了解长期接触放射线人群的健康状况,为放射性职业健康监护提供理论依据。方法于2016年以辽宁省内594名接触放射工作人员(接触组)和297名半年内未接触放射线人员(对照组)为调查对象,采用现况调查方法采集调查对象人口学基本信息、放射性职业接触状况、按照《放射工作人员职业健康管理办法》进行健康体检,采用一般描述性统计分析方法探讨长期接触低剂量放射线对人群的健康损害及影响因素。结果对照组人群白细胞计数异常检出率与眼晶状体浑浊率分别为0.015%、0.030%,放射线接触组人群白细胞计数异常检出率与晶状体浑浊率分别为0.042%、0.150%;与对照组比较,放射线接触组人群白细胞计数异常检出率及眼晶状体浑浊率明显升高,差异有统计学意义(P<0.05);2组人群血红蛋白、血小板、血糖异常检出率差异无统计学意义(P>0.05)。工龄0~9、10~19、≥20年放射线接触者眼晶状体浑浊率分别为0.039%、0.063%和0.133%;不同工龄放射线接触者眼晶状体浑浊率差异有统计学意义(P<0.05);从事放射治疗、介入放射、放射诊断、投照、工业探伤等放射工种之间各项健康指标差异无统计学意义(P>0.05)。结论长期低剂量射线暴露对人体健康具有一定影响,应加强放射线接触人群放射线防护意识,定期进行健康检查。     

Health risks associated with residential exposure to extremely low frequency electromagnetic radiation

Extremely low frequency electromagnetic radiation has received considerable attention recently as a possible threat to the health of persons living near high tension electric power lines, distribution substations, and even in close proximity to common household electric appliances. Results of epidemiological and laboratory research are examined to assess risks associated with magnetic fields generated by extremely low frequency electromagnetic sources. Health risks associated with such fields include a wide variety of ills ranging from disruption of normal circadian rhythms to childhood cancers. Risk assessment has been particularly difficult to determine in light of an ostensible lack of a dose-response relationship. Current media sensation fueled in part by an equivocal position adopted by the United States Environmental Protection Agency has contributed to the controversy. Recommendations for prudent avoidance of possible dangers are presented along with policy implications concerning health risks associated with magnetic fields.Roland J. Lamarine is Associate Professor of Health Education and Richard A. Narad is Assistant Professor of Health Services Administration, both in the Department of Health & Community Services at California State University, Chico, CA.     

彗星实验对放射工作人员DNA损伤评价研究

目的 观察和研究放射工作人员的DNA损伤情况,探讨不同工种、工龄与DNA损伤程度之间的关系.方法 研究对象分为对照组(100人)和放射组(51人);按照工种,将放射组分为放射科组、介入组和骨科组;按照工龄(年)的不同,分为<10、10～和20～组.用中性单细胞凝胶电泳对对照组和各放射组进行检测.结果 放射组与对照组DNA损伤的差异有显著性,放射组的尾部DNA百分含量(TDNA%)、尾矩(TM)、Oliver尾矩(OTM)明显高于对照组,不同工种、工龄间均差异有显著性(P<0.01);介入组高于放射科组,放射科组高于骨科组.结论 长期小剂量电离辐射能引起放射工作人员DNA损伤,随着工龄的增加DNA损伤程度加重.