Long exposure to monitors can affect eyesight. There's a reason for the warning labels on keyboards. Younger hands are even more susceptible to long-term damage. Becoming dependant on contact with people through chat rooms and instant message systems is very common for anyone developing self-image. Greater exposure to people on the Internet increases the chances of someone influencing your children negatively.
Children often forget there is still a completely enjoyable world away from computer screens.
Have children always consult their parents if they're not sure about something on the Internet. Sometimes the most effective method to prevent your children from exposure to negative material is to become involved in their Internet experience. If you can spend just a fraction of their online time with them, you can help influence the decisions they make when you're not around. How you use the Internet is a strong factor in determining the kinds of decisions your children will make when online. If you spend excessive amounts of time in chat rooms, for example, your children will see this as appropriate behavior.