Speculations on the origin of the ill-effects associated with the use of visual display terminals

There are increasing reports of a wide variety of unexplained ill-effects associated with the occupational use of visual display terminals (VDTs); these include psychological complaints such as headache, irritability, and fatigue, musculoskeletal pains, dry or burning eyes, deteriorating eyesight, cataracts, facial dermatitis, and pregnancy abnormalities. Many VDTs emit near-ultraviolet (UV-A) radiation in amounts ranging from 200 to 1500 times less than the present U.S. safety standard of 1.0 X 10(-3) W/cm2. Although the possibility of a radiation hazard from VDTs is widely discounted, various points of circumstantial evidence are marshalled in this paper in support of the hypothesis that prolonged exposure to even these low amounts of UV-A radiation may result in progressive increases in sensitivity to UV-A and in cumulative biologic damage. It is further proposed that UV-A produces the ill-effects by catabolizing vitamin A in skin and plasma into highly active metabolites, the gradual accumulation of which results in an endogenous form of vitamin A intoxication. In addition to producing the skin and systemic effects of hypervitaminosis A, these metabolites presumably enter the fetal circulation, leading to pregnancy abnormalities similar to those associated with high doses of the vitamin for the treatment of skin disorders.