Environmentalist: Discarding old appliances can be dangerous: refrigerators contain chlorofluorocarbons; electronic circuit boards and cathode-ray tubes often contain heavy metals like lead; and old fluorescent bulbs contain mercury, another heavy metal  When landfills are operated properly, such materials pose no threat  However, when landfills are not operated properly, lead and mercury from them contaminate groundwater, for example
On the other hand, when trash is incinerated, heavy metals poison the ash and escape into the air
Old fluorescent bulbs should be recycled.