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PubMedDate not supplied

Radiation exposure of aircrews.

Information is provided about the radiation to which aircrews are exposed and possible health consequences. Recommended radiation exposure limits are given. Crewmembers on commercial aircraft are exposed to higher doses of ionizing radiation than normally received by members of the general population in most parts of the world. The principal ionizing radiation is galactic cosmic radiation. On infrequent occasions, radiation from the sun leads to an increase in the ionizing radiation at aircraft flight altitudes. Radioactive cargo is another possible source of exposure to ionizing radiation. Crewmembers are exposed to nonionizing radiation in the form of electric and magnetic fields generated by the aircraft s electronic and electrical systems. Other potential sources of nonionizing radiation exposure are microwave radiation from the aircraft's weather radar, laser radiation, and ultraviolet radiation.

Aerospace Medicine↗
PubMed1983

Suppression of T-lymphocyte cytotoxicity following exposure to sinusoidally amplitude-modulated fields.

Significant inhibition of allogeneic cytotoxicity of the target cell MPC-11 by the murine cytotoxic T-lymphocyte line CTLL-1 was observed when the 4-h cytotoxicity assay was conducted in the presence of a 450-MHz field sinusoidally amplitude-modulated at 60 Hz. Exposure of the effector cells to the field prior to adding them to the target cells in the cytolytic assay resulted in a similar inhibition, suggesting a direct interaction of the field with the cytolytic T lymphocyte. The inhibition was preferentially expressed during the early allogeneic recognition phase. Field-exposed cytolytic cells recovered their full cytolytic capacity in 12.5 h. A differential susceptibility was observed with modulation frequencies from 0 to 100 Hz. Peak suppression occurred at 60 Hz modulation, with progressively smaller effects at 40, 16, and 3 Hz. The unmodulated carrier wave did not affect the cytotoxicity. Effects with 80- and 100-Hz modulation were smaller than at 60 Hz. These results demonstrate an inhibitory but recoverable effect by certain amplitude modulations of weak nonionizing radiation upon the cell-mediated cytolytic immune response.

Animals↗
PubMed1993

Overview of tritium: characteristics, sources, and problems.

Tritium has certain characteristics that present unique challenges for dosimetry and health-risk assessment. For example, in the gas form, tritium can diffuse through almost any container, including those made of steel, aluminum, and plastics. In the oxide form, tritium can generally not be detected by commonly used survey instruments. In the environment, tritium can be taken up by all hydrogen-containing molecules, distributing widely on a global scale. Tritium can be incorporated into humans through respiration, ingestion, and diffusion through skin. Its harmful effects are observed only when it is incorporated into the body. Several sources contribute to the inventory of tritium in our environment. These are 1) cosmic ray interaction with atmospheric molecules; 2) nuclear reactions in the earth's crust; 3) nuclear testing in the atmosphere during the 1950s and 1960s; 4) continuous release of tritium from nuclear power plants and tritium production facilities under normal operation; 5) incidental releases from these facilities; and 6) consumer products. An important future source will be nuclear fusion facilities expected to be developed for the purpose of electricity generation. The principal health physics problems associated with tritium are 1) the determination of the parameters for risk estimation with further reduction of their uncertainties (e.g., relative biological effectiveness and dose-rate dependency); 2) risk estimation from complex exposures to tritium in gas form, tritium in oxide form, tritium surface contamination, and other tritium-contaminated forms, with or without other ionizing radiations and/or nonionizing radiations; 3) the dose contributions of elemental tritium in the lung and from its oxidized tritium in the gastrointestinal tract; 4) prevention of tritium (in oxide form) intake and enhancement of tritium (oxide form) excretion from the human body; 5) precise health effects information for low-level tritium exposure; and 6) public acceptance of tritium leakage and waste disposal from reactors and fuel reprocessing plants.

Environmental Pollutants↗
PubMed2004

Effect of 910-MHz electromagnetic field on rat bone marrow.

Aiming to investigate the possibility of electromagnetic fields (EMF) developed by nonionizing radiation to be a noxious agent capable of inducing genotoxicity to humans, in the current study we have investigated the effect of 910-MHz EMF in rat bone marrow. Rats were exposed daily for 2 h over a period of 30 consecutive days. Studying bone marrow smears from EMF-exposed and sham-exposed animals, we observed an almost threefold increase of micronuclei (MN) in polychromatic erythrocytes (PCEs) after EMF exposure. An induction of MN was also observed in polymorphonuclear cells. The induction of MN in female rats was less than that in male rats. The results indicate that 910-MHz EMF could be considered as a noxious agent capable of producing genotoxic effects.

Animals↗
PubMed1999

Computational techniques for fast hyperthermia temperature optimization.

Hyperthermia temperature optimization involves arriving at a temperature distribution which minimizes a stated goal function, the goal function having a biological basis in maximizing tumor cell kill while not exceeding normal tissue toxicity. This involves the computationally intensive process of multiple evaluations of the temperature goal function, requiring repeated evaluations of the power deposition and its corresponding temperature distribution. Two computational schemes are proposed to expedite the temperature optimization process: (1) temperature distribution evaluation by superpositioning precomputed distributions, and (2) using representative tissue groups (rather than every point in the domain) to evaluate the goal function. The application of these schemes is illustrated with a typical optimization problem, as applied to symmetric and asymmetric, heterogeneous models. Application of these schemes reduced the optimization time on a DEC Alpha 1000 4/266 (Alpha is a registered trademark of Digital Equipment Corporation.) from several h to min, with little difference in results. The computational schemes, though demonstrated in the context of electromagnetic hyperthermia, are generally applicable to other forms of nonionizing radiation employed in hyperthermia therapy.

Humans↗
PubMed2004

[Cellular biology and public health].

Within the framework of the National Research and Development Program No. 1/016 /2001 the authors determined the population levels of ionizing and nonionizing radiations, elaborated the system of assays for detection of biological effects including dose-effect relationships, studied the roles of protective and sensitizing factors in the effect modification. The radium content of building materials were determined as well as the indoor radon activity concentrations and the magnetic induction fields around household equipment operating with 50 Hz. Biological dosimetry techniques were categorized according to the indication time. In addition, radiation sensitivity of intracellular antioxidant enzymes and the antioxidant capacity of blood sera were measured.

Air Pollutants, Radioactive↗
PubMed2006

[The role of chemical and physical factors in cancer development].

The author deals with the effects of environmental chemical-, and physical carcinogens playing predominant role in nearly 90% of the cancer development. Different steps of chemical carcinogenesis, classification and evaluation of carcinogens according to the criteria of International Agency for Research on Cancer, and the most important biological markers of genotoxic exposures are presented. Among physical agents the carcinogenic effects of ionizing and nonionizing radiations are demonstrated, including limited, inadequate or proved carcinogenic action of UV, microwave, static and low-frequency electric and magnetic fields.

Animals↗
PubMed2004

[General and oncologic mortality in cohort of television workers].

Study covered general and oncologic mortality in TV workers exposed to low levels of nonionizing radiation. Some workers' groups selected by occupation and length of service demonstrate reliably lower mortality with overall causes, cardiovascular diseases and malignancies, but increased mortality risk with malignancies of some locations.

Cohort Studies↗
PubMed1986

Photobiology. Basic science.

Photobiology is the study of the effects of nonionizing radiation on biologic systems. The biologic effect varies with the wavelength region of the radiation. The radiation is absorbed by molecules in skin such as DNA, protein or certain drugs. The molecules are changed chemically into products that initiate biochemical responses in the cells.

DNA↗
PubMed2000

Estimation of genome damage after exposure to ionizing radiation and ultrasound used in industry.

The application of ionizing radiation in industry for nondestructive testing entails a specific framework of working conditions that include field work, facilities with different radioactive sources, maintenance thereof without halting production, use of nonionizing radiation, and exposure to chemical agents. The present study gives an estimation of recent genome damage in two groups of subjects using chromosome aberration assay and micronucleus assay. The first group was exposed to (192)Ir and the second was simultaneously exposed to (192)Ir and ultrasound. The results show that both groups had higher values of chromosome aberrations and micronucleus frequency than controls. The group of examinees exposed both to (192)Ir and ultrasound had significantly more chromatid breaks, acentric fragments, and dicentric chromosomes, and had a significantly higher frequency of micronuclei than subjects exposed to (192)Ir only. The study suggests that the detected differences in the genome damage may be attributed to the action of ultrasound. This study confirms the dosimetry data for ionizing radiation, which indicate that the methods used in industrial radiography and the usage of nonionizing radiation entail an increased health risk. In the absence of personal dosimeters for nonionizing radiation and chemical agents, biomonitoring provides reliable parameters for estimation of genome damage and may lead to improvements in working conditions and radiation safety programs.

Adult↗