csscan shows lossy data

I didn't find any documentation on how to change the character set from UTF8 to WE8ISO8859P1.

May be this is immature question. 

But I am in this kind of situation. 

my development environment is using WE8ISO8859P1 nls character set and production us using UTF8 ( Some how)

Now my database doesn't allow me to store the 25 French character into Prod database, but Dev.  Env. allow me to do so. 

csscan shows me ( UTF8 to WE8ISO8859P1 ) lossy data. 

Now I have two questions:

1. Can I change the character set from UTF8 to WE8ISO8859P1.

2. Does this change the French characters if I do so.