Spontaneous abortion among women using video display terminals

This case-base study with a source population of 214 108 commercial and clerical workers investigated the risk of adverse pregnancy outcome among women working with a video display terminal (VDT) in Denmark. A subpopulation was obtained by register linkage between a trade union membership file, the Medical Birth Register, and the National Register of In-Patients. In two years 24,352 pregnancy outcomes were registered, 2248 spontaneous abortions were recorded, and a base sample of 2252 pregnancies was randomly selected. Data on VDT use, job stress, ergonomic factors, and life-style factors were collected with questionnaires sent to 6212 women and 426 employers. There was no increased risk of medically verified spontaneous abortion among women with VDT use. The relative risk for women exposed to any degree of use was 0.94 (95% confidence interval 0.77-1.14). Ergonomic work load and job stress were not confounders.     

Lacrimal hyposecretion in women working with video terminals

Tests of vision and lacrimal secretion were performed as part of a general medical check-up among women employed at video-terminals in a bank. The tests were taken by three groups of 100 employees each. The first group consisted of full-time (eight hours) employees, the second of those working part-time (the time spent at a video-terminal daily was never less than two hours of continuous work) and a third group of control subjects having different clerical jobs but working in the premises with video-terminals. Diminished lacrimal secretion was most often present among full-time workers (20 per cent). A statistically significant difference in lacrimal secretion was observed between the first and the second group of examinees. There was no significant difference between the second group and the controls.     

Psychological factors and visual fatigue in working with video display terminals

OBJECTIVES—To examine the part played by psychological factors in complaints about visual health reported by banking officers who work at video display terminals (VDTs).
METHODS—Out of a population of 385 bank workers, a group of 212 subjects without organic visual disturbances (as determined by opthalmological examination) who share a work environment and job duties was selected. Three questionnaires were administered to these subjects: (a) the NIOSH job stress questionnaire; (b) a questionnaire investigating subjective discomfort related to environmental and lighting conditions of the workplace; (c) a questionnaire on the existence of oculovisual disturbances. Correlation and multiple regression analyses were performed to examine for the presence of predictors of asthenopia.
RESULTS—Social support, group conflict, self esteem, work satisfaction, and underuse of skills were found to be predictors of visual complaints; social support played a part also as a moderating factor in the stress and strain model; this model accounted for 30% of the variance. Subjective environmental factors, although in some cases significantly correlated with asthenopia, were not found to be strong predictors of the symptoms.
CONCLUSIONS—Some part of the complaints about visual health reported by VDT workers are likely indirect expressions of psychological discomfort related to working conditions.


Keywords: asthenopia; social support; stress     

Work with video display terminals among office employees. V. Dermatologic factors

According to some reports, mainly from Norway, work with a video display terminal (VDT) has been suspected to cause skin rashes. In conjunction with an epidemiologic study of some 550 office employees, 74 persons, who complained of skin symptoms, were examined by occupational dermatologists. The objective was to see whether the findings from earlier reports could be confirmed, whether any type of rash could be suspected to depend on VDT work, and whether positive findings might be explained by means of physical data. Many different diagnoses were made, but no case demonstrated the clinical picture described among VDT operators from Norway. Subjects with seborrheic dermatitis, acne, and rosacea were overrepresented in the exposed group. Whether this occurrence was due to physical factors, psychological factors, or pure chance is still unclear. This study and observations from our clinic imply that a relationship might exist between VDT work and aggravation of seborrheic dermatitis, acne, and rosacea and probably poikiloderma of Civatte.     

Work with video display terminals among office employees. II. Physical exposure factors

This is the second report in a major epidemiologic health investigation on work with a video display terminal (VDT). The first study showed that VDT operators reported more eye discomfort than a reference group not employed in VDT work and that women reported more eye discomfort, musculoskeletal complaints, headache, and skin disorders than men, regardless of whether they worked with a VDT or not. The present report contains the results of the occupational hygiene measurements (indoor climate, lighting and electrostatic conditions). Considerable differences were found between VDT operators and referents and also between sexes. Indications were obtained of a possible relationship between eye discomfort and luminance ratios in the working field of vision. Otherwise, no association could be established between occupational exposure factors and subjective eye discomfort, musculoskeletal complaints, headache, or skin disorders.     

Changes in the functional state of the visual analyzer in operators working with video display terminals]

Research in laboratory and on-site conditions was performed to establish correlations between the visual analyzer's functional shifts in display operators, and the duration of work, the type of the screen used (coloured or non-coloured), the duration of the eyes, fixation on the screen, as well as sex related differences.     

Work with video display terminals among office employees. I. Subjective symptoms and discomfort

Subjective symptoms and discomfort were evaluated by means of a questionnaire and compared between approximately 400 video display terminal (VDT) operators and 150 selected referents. Previous and current illnesses, educational status, and smoking and drinking 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 disorders 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 workhours 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 enterprises, 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.     

Psychological and ergonomic aspects of work with video display terminals.

Forty-nine operators of video display terminals were administered a questionnaire on subjective complaints in connection with work conditions. Measurements of non-ionizing and ionizing radiation emissions during normal operation of video display terminals showed them to be within permissible levels. A detailed ergonomic analysis of equipment and workstations was also performed. Results showed a high occurrence of subjective complaints, significant differences between age subgroups in a few variables, and significant correlation between sets of variables of some perceived ergonomic features and subjective complaints.     

Fecundity and the use of video display terminals.

The association between prolonged waiting time to pregnancy and the use of a video display terminal (VDT) was investigated among commercial and clerical employees in Denmark. Information on 24,352 pregnancies was obtained through register linkage with two national registers. A random sample of 2252 pregnancies was drawn, and the women were asked for information on waiting time to pregnancy, occupational exposures, and life-style factors. The overall exposure to a VDT indicated a slightly increased association with prolonged waiting time to pregnancy. The relative risks for waiting more than one year were 1.23, 0.77, and 1.61 for the women who worked with a VDT for 1-10, 11-20, and > or = 21 h per week, respectively. Only the last relative risk was statistically significant. The results could be explained by methodological shortcomings such as recall bias or confounding by alternative factors that might affect time to pregnancy, or simply by the lack of statistical power.     

视屏显示终端的卫生学观察

本文为视屏显示终端对操作人员健康影响的调查,表明视屏显示终端主要影响操作人员的神经系统,眼和骨骼肌系统。其原因有功放学、环境因素和视屏物理因素等,提示要加强对视屏显示终端操作人员的防护措施。     

Measurements of extremely low-frequency magnetic fields around video display terminals

The extremely low-frequency (ELF) magnetic field emissions of seven video display terminal (VDT) models were measured. A measuring coil with a linearized frequency response (50 Hz to 25 kHz) was used. The dominating ELF magnetic field around the terminals was the 50 or 60 Hz asymmetric triangular waveform from the vertical deflection coil of the cathode ray tube. At the distance of 50 cm, the magnetic field strength was still slightly higher than the background level in usual office rooms, but several orders of magnitude lower than the thresholds of known interaction mechanisms. Some recent experiments suggest that certain biological effects may occur at field strengths only a few times higher than those found at the position of VDT operators, but the significance of these effects to human health is not known.     

Magnetic fields of video display terminals and spontaneous abortion.

The aim of this study was to examine whether work with a video display terminal and exposure to the magnetic fields of video display terminals are related to spontaneous abortion. The study was conducted among women employed as bank clerks and clerical workers in three companies in Finland. The cases (191 spontaneous abortions) and controls (394 births) were identified from Finnish medical registers for the years 1975-1985. Use of video display terminals was defined using the workers' own reports and information provided by the companies. The assessment of exposure to the magnetic fields was based on measurements of the fields of video display terminals. The odds ratio for spontaneous abortion for working with video display terminals was not increased (odds ratio = 1.1, 95% confidence interval 0.7-1.6). However, the odds ratio for workers who had used a video display terminal with a high level of extremely low frequency magnetic fields (> 0.9 microT) was 3.4 (95% confidence interval 1.4-8.6) compared with workers using a terminal with a low level of these magnetic fields (< 0.4 microT). Adjustment for ergonomic factors and mental work load factors changed the odds ratio for magnetic field exposure only very slightly. The findings suggest the need for future studies with assessment of exposure to the magnetic fields in the actual working environment to confirm the possible risk.     

Exposure to video display terminals and risk of spontaneous abortion

Clusters of spontaneous abortion among video display terminal (VDT) users in North America and Canada in the late 1970s aroused suspicion about the potential risk of an association between VDT exposure and pregnancy outcome. This case-control study considered the association between VDT use and the risk of miscarriage. Cases were 508 women admitted for spontaneous abortion to the Clinica Luigi Mangiagalli and a network of obstetric departments in the Milan area. Controls were 1,148 women who gave birth at term to healthy infants on randomly selected days at the same hospitals where cases were identified. No association emerged between VDT exposure and spontaneous abortion, the estimated odds ratio being 1.0 (95% CI: 0.8–1.2). This evidence agrees with studies conducted in different countries by various authors. Am. J. Ind. Med. 32:403–407, 1997. © 1997 Wiley-Liss, Inc.