A number of persons have expressed concern about possible health ers to workers who use devices called video-display terminals (终端) or VDTs．These are the devices used to show computer information．Some reports link VDTs to health disorders including eye problems and muscle problems．Even the health of the pregnant women and their unborn babies is said to be enered．Video-display terminals produce low levels of the electromagnetic radiation(电磁辐射)．Experts say most modern VDTs have been designed to limit the ers from such radiation．However, study shows that even low levels of electromagnetic radiations can affect the growth of the cells．As a result, some doctors advise women to stop working with VDTs while they are pregnant．One study found women who work with VDTs in early pregnancy are more likely than others to have their pregnancy end unexpectedly．Researchers said that this does not necessarily mean that VDTs themselves cause problems．Some experts said the findings show working conditions, not the machines, cause the problems．Law makers in m6re than American states have proposed bills to control working conditions for VDT operators.
What kind of disease does the VDTs cause?