Investigators say more than 80 toxic waste sites across Long Island that were supposed to have been cleaned up are still hazardous. The Department of Environmental Conservation is planning to investigate for vapors, which could possibly seep into homes through the aquifer system. A DEC spokesperson says scientific models that were used to predict sites for vapor intrusion have now been changed to account for lower values of soil vapor.The DEC says the sites ranked most likely to have problems will be dealt with first. That list isn't due out until December. The state says the original owners of the contaminated properties will have to pay for any additional cleanup.