The Environment Agency has now ruled that LCD screens contain hazardous components, which will have an impact on businesses that have been using flat screens for some time and may now be considering replacing them. The liquid crystal substances themselves are not hazardous, but the back lighting fluorescent tubes are, as they contain mercury.
According to the Environment Agency website (which will not be winning any awards for accessibility or functionality in the near future):
On the evidence we currently have, all electrical equipment containing cathode ray tubes and most LCD televisions should be classified as hazardous once they have been designated waste. Waste Plasma displays and televisions do not appear to contain hazardous components and at the present time we do not consider these hazardous.
If the hazardous components referenced above are removed from the waste electric or electronic equipment, and there are no other hazardous components present, the equipment will not be classified as hazardous.
For more informationm on the subject, see the Hazardous Waste Links below:
Environment Agency Website
Environment Agency PDF