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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recently a number of studies were carried on concerning malignant neoplasms, mainly leukemia, in workers exposed to electromagnetic fields. The studies focused upon power industry workers operating transmission--distribution lines, power stations, transformer stations and distribution substations which work at power--line frequencies. A review of selected literature was prepared concentrating on the methods describing conditions of exposure to e-m ELF fields as well as on the results of epidemiological studies. Also, the results of experiments carried on in Poland based on materials accessible only to a compact group of power industry experts were presented.
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PMID:[Occupational exposure to electromagnetic fields of extremely low frequency (with particular regard to power plants) and the health status of workers, based on a literature review]. 220 82

Although the exact mechanism for the progression of myelofibrosis in acute megakaryoblastic leukaemia is unclear, certain humoral factors released from the proliferating megakaryoblasts that are unable to store these factors in their defective alpha-granules, including platelet derived growth factor (PDGF), fibroblast growth factors (FGF), platelet factor-4 (PF-4), transforming growth factor-beta (TGF-beta) and beta-thromboglobulin, could result in increased collagen synthesis by bone marrow fibroblasts. Recently, the human megakaryoblastic leukaemia cell line MEG-01 has been shown to produce both TGF-beta and PF-4 which have enhanced the growth of bone marrow fibroblasts. Therefore, we have examined the presence of a fibroblast growth stimulating activity and the humoral factors that might be responsible for it in the supernatant of the human megakaryoblastic leukaemia cell line ELF-153 recently established in our laboratory from a patient with acute myelofibrosis. A new fibroblast growth stimulating activity has been identified in the supernatant of the ELF-153 human megakaryoblastic leukaemia cell line that is independent of the percentage of fetal calf serum in NRK-49F fibroblast agar clonogenic assays and is not due to any of the known fibroblast growth stimulating humoral factors including PDGF, epithelial growth factor, TGF-alpha or beta, tumour necrosis factor-alpha, interleukin-1, 2, 4 or 6, FGF, fibronectin, PF-4 and factor VIII AG. Also, in vivo, subcutaneous injection of ELF-153 megakaryoblastic leukaemia cells into nude mice formed, in three out of the five mice after 6 weeks, subcutaneous tumours with a very rigid texture whose histological examination revealed dense infiltration by blast cells and pronounced reticular fibrosis. Immunohistochemistry demonstrated exclusive deposition of collagen III in the extracellular matrix whereas laminin and collagen IV were absent.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A new fibroblast growth stimulating activity from the human megakaryoblastic leukaemia cell line ELF-153: in vitro and in vivo findings. 748 50

This paper summarizes the published literature and current problems relating to possible cancerogenic effects of occupational and residential exposure to ELF electromagnetic fields at levels slightly above ambient background. There are several suggestions that such an exposure may increase the risk of cancer, but these studies failed to provide conclusive indications. The present state of uncertainty led to a variety of recommendations and statements being made concerning restrictions to the exposure of people to ELF electromagnetic fields. Attempts to detect direct chromosomal damage from ELF electromagnetic fields have proven negative, while results on cancer promotion have been controversial. On the basis of several epidemiological studies on occupational exposure, an increased risk of leukemia, brain cancer and male breast cancer is apparent; the literature on residential exposure provides some evidence of an effect on childhood cancer, especially leukemia; however, when interpreting these results some major methodological concerns should be kept in mind. In conclusion, the public concern and potential public health impact of this environmental agent argue strongly for addressing further research in order to identify mechanisms of action on biological systems, to define the proper assessment of exposure and to obtain good epidemiological evidence.
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PMID:[Carcinogenic risk of extremely-low-frequency electromagnetic fields: state of the art]. 773 4

The purpose of this paper is to present the assessment of magnetic field exposure conducted as a part of a nested case-control investigation of leukemia mortality in telephone lineworkers. For the purposes of exposure classification, telephone company jobs were initially divided into two classes: those with potential for working in an electric environment, referred to as linework jobs, and those not working in an electric environment, referred to as nonlinework jobs. Linework jobs were further divided into the following four categories: outside plant technicians (OPT), installation/maintenance/repair (IMR) technicians, central office technicians (COT), and cable splicing technicians (CST). These job groupings were based on similarity of work tasks and exposure environments. Emdex data-logging dosimeters were used to measure personal exposures to ELF magnetic fields for 204 telephone company workers. Three general classes of exposure indices were calculated for each exposure record: measures of central tendency, measures of peak or maximum exposure, and measures of exposure variability. CSTs had the highest full-shift mean and median exposure, 4.3 and 3.2 mG, respectively. CSTs also ranked the highest, with average peak, average 95th percentile, and average time above background equal to 99.2 mG, 11.1 mG, and 156 min, respectively. In addition, the results suggest the OPT and IMR technicians have exposures similar to nonlineworkers. Exposure classifications, therefore, which misclassify all lineworkers into one "telephone lineworker" job grouping are not appropriate and future studies should concentrate on cable splicing technicians.
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PMID:60 Hertz magnetic field exposure assessment for an investigation of leukemia in telephone lineworkers. 783 15

Electrification in developed countries has progressively increased the mean level of extremely low-frequency electromagnetic fields (ELF-EMFs) to which populations are exposed; these humanmade fields are substantially above the naturally occurring ambient electric and magnetic fields of approximately 10(-4) Vm(-1) and approximately 10(-13) T, respectively. Several epidemiological studies have concluded that ELF-EMFs may be linked to an increased risk of cancer, particularly childhood leukemia. These observations have been reinforced by cellular studies reporting EMF-induced effects on biological systems, most notably on the activity of components of the pathways that regulate cell proliferation. However, the limited number of attempts to directly replicate these experimental findings have been almost uniformly unsuccessful, and no EMF-induced biological response has yet been replicated in independent laboratories. Many of the most well-defined effects have come from gene expression studies; several attempts have been made recently to repeat these key findings. This review analyses these studies and summarizes other reports of major cellular responses to EMFs and the published attempts at replication. The opening sections discuss quantitative aspects of exposure to EMFs and the incidence of cancers that have been correlated with such fields. The concluding section considers the problems that confront research in this area and suggests feasible strategies.
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PMID:Biological responses to electromagnetic fields. 953 13

A physically based model for residential magnetic fields from electric transmission and distribution wiring was developed to reanalyze the Los Angeles study of childhood leukemia by London et al. For this exposure model, magnetic field measurements were fitted to a function of wire configuration attributes that was derived from a multipole expansion of the Law of Biot and Savart. The model parameters were determined by nonlinear regression techniques, using wiring data, distances, and the geometric mean of the ELF magnetic field magnitude from 24-h bedroom measurements taken at 288 homes during the epidemiologic study. The best fit to the measurement data was obtained with separate models for the two major utilities serving Los Angeles County. This model's predictions produced a correlation of 0.40 with the measured fields, an improvement on the 0.27 correlation obtained with the Wertheimer-Leeper (WL) wire code. For the leukemia risk analysis in a companion paper, the regression model predicts exposures to the 24-h geometric mean of the ELF magnetic fields in Los Angeles homes where only wiring data and distances have been obtained. Since these input parameters for the exposure model usually do not change for many years, the predicted magnetic fields will be stable over long time periods, just like the WL code. If the geometric mean is not the exposure metric associated with cancer, this regression technique could be used to estimate long-term exposures to temporal variability metrics and other characteristics of the ELF magnetic field which may be cancer risk factors.
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PMID:Residential magnetic fields predicted from wiring configurations: I. Exposure model. 1049 5

Two epidemiologic studies have reported increased risk of childhood leukemia associated with the length of time children watched television (TV) programs or played video games connected to TV sets. To evaluate magnetic field exposures resulting from these activities, the static, ELF, and VLF magnetic fields produced by 72 TV sets used by children to watch TV programs and 34 TV sets used to play video games were characterized in a field study conducted in Washington DC and its Maryland suburbs. The resulting TV-specific magnetic field data were combined with information collected through questionnaires to estimate the magnetic field exposure levels associated with TV watching and video game playing. The geometric means of the ELF and VLF exposure levels so calculated were 0.0091 and 0.0016 microT, respectively, for children watching TV programs and 0.023 and 0.0038 microT, respectively, for children playing video games. Geometric means of ambient ELF and VLF levels with TV sets turned off were 0.10 and 0.0027 microT, respectively. Summed over the ELF frequency range (6-3066 Hz), the exposure levels were small compared to ambient levels. However, in restricted ELF frequency ranges (120 Hz and 606-3066 Hz) and in the VLF band, TV exposure levels were comparable to or larger than normal ambient levels. Even so, the strengths of the 120 Hz or 606-3066 Hz components of TV fields were small relative to the overall ambient levels. Consequently, our results provide little support for a linkage between childhood leukemia and exposure to the ELF magnetic fields produced by TV sets. Our results do suggest that any future research on possible health effects of magnetic fields from television sets might focus on the VLF electric and magnetic fields produced by TV sets because of their enhanced ability relative to ELF fields to induce electric currents.
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PMID:Children's exposure to magnetic fields produced by U.S. television sets used for viewing programs and playing video games. 1072 21

As leukemia is one of the health hazards that is sometimes associated with exposure to extreme low frequency fields, we studied the in vitro effects of ELF fields on haemopoietic cell proliferation. First, the cytotoxic effect of 80 microT, 50 Hz magnetic fields on 3T3 cell proliferation was investigated using the neutral red test. Many chemicals are believed to cause damage because they interfere with basal or "housekeeping" cell functions. The basal cell functions are present in every cell. Non-specialized, actively dividing cells are suitable for measuring cytotoxic effects. Cytotoxic doses can be identified by exposing actively dividing cells in vitro and measuring growth inhibition caused by interference with these basal cell functions. 80 microT, 50 Hz magnetic fields caused no cytotoxicity: we were not able to demonstrate any interference with essential cell functions in the non-differentiated 3T3 cell line. Furthermore, the in vitro effects of ELF fields on murine haemopoietic and stromal stem cell proliferation were studied. Haemopoiesis is a continuous process, where mature blood cells are replaced by the proliferation and differentiation of more primitive progenitor and stem cells. Blood formation is tightly regulated by the stromal micro-environment. Exposure of murine bone marrow cells, from male and female mice, to 80 microT (50 Hz) magnetic fields showed a reduction in the proliferation and differentiation of the granulocyte-macrophage progenitor (CFU-GM) compared to non-exposed bone marrow cells. The results on the effect of the ELF-field on stromal stem cell proliferation (CFU-f) are somewhat equivocal at the moment. CFU-f from female mice showed a reduction while CFU-f from male mice were not decreased.
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PMID:Haemopoietic cell proliferation in murine bone marrow cells exposed to extreme low frequency (ELF) electromagnetic fields. 1156 62

We review the epidemiological evidence on childhood leukemia and residential exposure to 50/60 Hz magnetic fields. The possibility of carcinogenic effects of power frequency magnetic fields (ELF-EMF), at levels below units of micro tesla (microT), was first raised in 1979 by a case-control study on childhood cancer carried out in Denver, USA. In that study, excess risks of total cancer and leukemia were observed among children living in homes with "high or very high current configuration", as categorised on the basis of proximity to electric lines and transformers. Many other epidemiological studies have been published since then, characterised by improved--although still not optimal--methods of exposure assessment. At the end of 2000, the epidemiological evidence to support the association between exposure to extremely-low-frequency magnetic fields and the risk of childhood leukemia is less consistent than what was observed in the mid 90s. At the same time, a growing body of experimental evidence has accumulated against both a direct and a promoting carcinogenic effect of ELF-EMF. Such "negative" experimental evidence hampers a causal interpretation of the "positive" epidemiological studies.
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PMID:[Infantile leukemia and exposure to 50/60 Hz magnetic fields: review of epidemiologic evidence in 2000]. 1175 79

A recent epidemiologic study reported associations between leukemia risk in children and their personal use of television (TV) sets, hair dryers, and stereo headsets, and the prenatal use by their mothers of sewing machines. To provide exposure data to aid in the interpretation of these findings, extremely and very low frequency (ELF and VLF) magnetic fields produced by a sample of each type of appliance were characterized in a field study of volunteers conducted in Washington DC and its Maryland suburbs. Questionnaire data regarding children's or mothers' patterns of usage of each type of appliance were also collected. ELF magnetic fields measured 10 cm from the nozzles of hair dryers were elevated over the ambient by a mean factor of 17 when these devices were in use. Fields near headsets being used to listen to music were not distinguishable from ambient levels except at frequencies below and well above 60 Hz and, even then, field levels were < 0.01 microT. Home sewing machines produced ELF magnetic fields that were elevated by a factor of 2.8 over ambient levels at the front surfaces of the lower abdomens of mothers. Estimated mean daily times of usage of hair dryers, stereo headsets, and sewing machines were 2.6, 19, and 17 minutes, respectively. These data and previously published data on TV sets, do not provide a consistent picture of increased (or decreased) leukemia risk in relation to increasing peak or time weighted average (TWA) ELF magnetic field exposure. The data could, however, conceivably be compatible with some more complex biophysical model with unknown properties. Overall, the results of this study provide little evidence supporting the hypothesis that peak or TWA ELF magnetic fields produced by appliances are causally related to the risk of childhood leukemia in children.
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PMID:Magnetic fields produced by hand held hair dryers, stereo headsets, home sewing machines, and electric clocks. 1179 2


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