Biological and health effects associated with some non-ionising radiations
There is increasing public concern over the possible harmful effects of extra-low-frequency (ELF) electromagnetic (em) fields. A variety of harmful effects have been linked with em field exposure, for example depression and suicide, carcinogenesis, birth defects, and spontaneous abortion. The epidemiological evidence, especially the more recent studies, suggests that there may be a small increased risk of childhood cancers in those living near overhead power lines. However laboratory evidence to date does not support this link. An epidemiological correlation does not necessarily imply a causal relationship: to confirm such a relationship, biological and laboratory evidence is required. This work studies the magnitude of human exposure to ELF magnetic fields from overhead power lines and visual display units (VDUs) and also investigates possible health effects at the microscopic level through cell culture experiments. From the epidemiological evidence, an effect threshold of approximately 300 nT was estimated. Detailed magnetic field distributions were measured round a variety of visual display units and only a very few emitted magnetic fields even close to the 300 nT threshold. Following an in-depth case study of a VDU operator who suffered from a combination of symptoms including eyestrain and headaches, a study of the health of nearly 200 office workers and VDU users was set up. The aims of the study were to investigate the range and severity of symptoms suffered by VDU users, to investigate possible causes and to study response to VDU work at an individual level. It was found that those working between 10 and 30 hours per week at a VDU were more likely to suffer symptoms of ill health. In contrast, those working more than 30 hours per week at a VDU were not more likely to suffer symptoms when compared with a control group of those working less than 10 hours per week at a VDU. In particular, increased reporting of eye problems and fatigue were most strongly associated with VDU work.