When office automation exploded in the 1980s, there was controversy of many kinds related to computer equipment. Some believed that radiation emitted by computer moni- tors created risks to fetuses. Much of the concern arose from clusters of female office workers who miscarried or bore children with birth defects. One 5-year study found no effect on miscarriages for women who work on VDTs for fewer than 20h per week and a 5% greater incidence of miscarriage for those who work at VDTs more than 20hr per week. The controversy seems to have disappeared, because studies showed no strong link between VDT use and miscarriages and birth defects. In addition, manufacturers reduced the emission levels.