FACTS ABOUT OZONE AND SKIN CANCER



Q.   Does the depletion of stratos~heric ozone by man-made
     chlorofluorocarbons (CFCs) have any effect on skin cancer incidence?

A.   Not at present, since there is a 10-20 year lag time between exposure
     to ultraviolet light and the development of skin malignancy.  There
     will be an increase in skin cancer in the future due to ozone
     depletion caused by CFCs.


Q.   What are CFCs and why can't all countries ban them?

A.   Chlorofluorocarbons (CFCs) were developed in 1930 as safe alternatives
     to toxic and flammable refrigerants that were being used at the time.
     CFCs are chemically unique compounds that are nonreactive and have very
     special and useful chemical properties.  They are nontoxic to humans
     and yet have ideal vaporization temperatures for air conditioning, for
     expanding plastic foam for insulation for appliances and buildings.
     They also are excellent cleaning agents for delicate electronic and
     mechanical instruments.  CFCs are inexpensive to manufacture, while
     substitutes will be much more expensive to produce and therefore more
     costly for smaller countries.

     There are presently bans in the United States only on aerosol
     propellants used in spray cans.  Under an international agreement
     signed by 42 nations in 1987, emissions of chlorofluorocarbons are to
     be reduced by 50 percent in the next decade by industrial countries,
     and over a longer period by developing nations.  There are plans for a
     total ban of CFCs by the year 2000.  It is estimated that 224,000 tons
     of propellant were released in 1989.


Q.   How does ozone affect the amount of ultraviolet radiation that reaches
     the earth?

A.   The ozone filter is a crucial protection against the carcinogenic
     impact of sunlight on humans.  Ozone preferentially blocks ultraviolet
     B radiation that damages DNA.  The ozone layer dramatically decreases
     the amount of ultraviolet B radiation that reaches the earth, but has
     little effect on ultraviolet A radiation.  Recent data have shown that
     there is a recurrent ozone hole in the stratosphere over Antarctica in
     which ozone levels have been reduced as much as 60 percent.
     Atmospheric concentrations of trace gases such as carbon dioxide,
     methane, nitrous oxide, and CFCs have been increasing at an alarming
     rate.
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