🚀 go-pugleaf

Greig Ebeling wrote:
> 
> Jonathan Shanklin <j.shanklin@bas.ac.uk> wrote:
> 
> >I guess it all depends on what you mean by 'no significant bio effect'.
> >There certainly is an effect on plankton, there may be an effect on
> >species composition.  [See Robert Parson's FAQ].  Other substances were
> >thought not to have a significant bio effect at the time [DDT is perhaps
> >an example, though this certainly had a direct bio effect] but
> >eventually problems were seen at the top of the food chain.  Of course
> >if this takes 50 years it probably won't affect you, and therefore isn't
> >'a significant bio effect'.
> 

Correct me if I'm wrong, but isn't UV-B just another form of ionizing
radiation, which originates in space, allbeit with very short penetration
ability.  If ionizing radiation is known to cause cancer in other organs and
tissues, then is it not logical that UV-B should cause skin cancer with high
exposures.  Latency plays the same role in UV-B exposre as with other ionizing
radiation induced cancers.

> DDT is an excellent example.  It is known that DDT accumulates in the
> food chain (quite dramatically), and so it was banned.  But it was
> never proved to have negative bio effects.  It was banned on the basis
> of the "precautionary principle".
> 

Not so!  DDT has been clearly implicated in the lack of reproductive success
in birds, particularly raptors, due to thinning of the egg shell.  DDE, a 
biological degradation product of DDT, has estrogenic effects and may be
responsible for the feminization of species such as toads and alligators
in south Florida.

> CFCs are banned on the same principle.  My point is: that like DDT,
> CFCs have a value to the community, and removing it will COST the
> community.  Is this cost appropriate relative to the negative
> biological effects it [may/will] have, considering that there are
> other uses for environmental protection resources?

There are a multitude of componds which can serve as refigerants which
have lesser environmental consequences than the most noxious CFCs.  The
problem is the cost of reengineering.  If industry had proceeded more
cautiously in implementing these new compounds the retrofit would have
been significantly less costly.

Dennis Nelson