Occupational exposure to low-frequency electromagnetic fields (EMF) was studied in 250 leukemia patients and 261 brain-tumor cases, diagnosed in 1983-87 and compared with a control group of 1,121 randomly selected men, from the mid-region of Sweden, 1983-87. We based the exposure assessment on measurements from 1,015 different workplaces. On the basis of the job held longest during the 10-year period before diagnosis, we found an association between the average, daily, mean level of EMF and chronic lymphocytic leukemia (CLL). The risk increased with increasing level of exposure. The odds ratios (OR) and the 95 percent confidence interval (CI) for three consecutive levels of exposure were: 1.1 (CI = 0.5-2.3); 2.2 (CI = 1.1-4.3); 3.0 (CI = 1.6-5.8), respectively. No association was observed for acute myeloid leukemia (OR = 1.0, CI = 0.5-1.8; OR = 0.8, CI = 0.4-1.6; OR = 1.0, CI = 0.6-1.9). For brain tumors, the corresponding risk estimates were 1.0 (CI = 0.7-1.6); 1.5 (CI = 1.0-2.2); 1.4 (CI = 0.9-2.1). Different EMF indices were tested. Tasks with frequent or large variations between high and low field-densities (high standard deviation) were more common among CLL subjects. For brain tumors, a prolonged high level (high median values) showed the strongest association. Confounding by place of residence, smoking, benzene, ionizing radiation, pesticides, and solvents was evaluated, and these factors did not seem to have a decisive influence on the associations. We also analyzed other potential sources of bias. For CLL, there were indications of an excess number of low-exposure subjects among non-responders, which, to some extent, may have enhanced but not caused the risk estimates obtained. Our conclusion is that the study supports the hypothesis that occupational EMF exposure is a hazard in the development of certain cancers.

KNAVE BO, WIBOM RI, VOSS M, HEDSTROM LD, BEROQVIST UOV: Work with video display terminals among office employees: I Subjective symptoms and discomfort. Scand J Work En viron Health II (1985) 457-466. Subjective symptoms and discomfort were evaluated by means of a questionnaire and compared between approximately 400 video display terminal (VDT) operator s and 150 selected referents . Previous and current illnesses, educational status, and smoking and drinkin g habits were also studied. The results showed the VDT operators to have more eye discomfort and possibly also more musculoskeletal discomfort in the shoulders, neck, and back than the referents. The VDT group also reported more skin disorders. In addition, women reported consistently more disorder s than men, regardless of whether or not they were employed in VDT work . Women in general displayed greater morbidity than men. Eye discomfort, musculoskeletal discomfort, headache, and skin disorders were found to be significantly correlated in the material. The results also indicated that total daily workhou rs and time spent looking at the VDT screen were related to the degree of discomfort. Even when the subjects were divided into subgroups with reference to the various enterpri ses, the types of work and the makes of VDT, the differences obtained in the degree of discomfort appeared to be due to variations in the length of workhours.Key terms: epidemiologic study, eye discomfort, headache, musculoskeletal complaint s, skin disorders, VDT make, workho urs, workplace, worktask.Various subjective symptoms, eg , ocular discomfort, musculoskeletal complaints, and headache, have been related to work at a video display terminal (VDT) ever since the VDT was fir st introduced to worklife. (See references 1,2,8, l l , 13.) Certain facial skin disorders have also been described (9).The present epidemiologic health investigation involved about 400 VDT operators and ISO selected referen ts (ie, office employees without VDT work) in the Stockholm region. Various occupational exposure factors were measured from the screen itself, from the workstation, and from the work routine s. Subjective symptoms and d iscomforts in relation to the eyes , arms, back, and skin and headache were evaluated from questionnaires, a s well as previous and current di seases. In formation on eye status wa s obtained by means of routine ophthalmologic examinations . Certain special studies were made of accommodation, co nvergence, and refraction during the workday. Those subjects complaining of skin disorders on the face, the neck, and the hands were examined by dermatologists.The aim of the inve stigation was to compare the occurrence of subjective symptoms and discomfort between VDT operators and referents and to study the

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Long-term exposure to jet fuel. II. A cross-sectional epidemiologic investigation on occupationally exposed industrial workers with special reference to the nervous system.