CFC Issues - Refrigerants
The geothermal heat pumps currently being marketed use HCFC-22, or R-22, as the refrigerant. This is the same refrigerant being used in almost all residential and commercial air conditioners and heat pumps, except for large centrifugal chillers.
Chemically, HCFC-22 is chlorofluoromethane, CHClF2 . No health or safety concerns have been identified with R-22. It is classified in the A1 Safety Group, the safest group, in the American National Standard ANSI/ASHRAE 34-2001. The toxicity group A indicates no toxicity identified at concentration less than or equal to 400 parts per million. Group 1 indicates no flame propagation.
As with any refrigerant, it should be handled carefully. It should never be vented to the atmosphere. All equipment using refrigerants should be properly maintained by a certified technician.