Dear ,
I’m writing to express my concern about/put forward my suggestions about .(or I’m writing to call on you to .) I have noticed/heard that .I’m really worried/glad about it.
It is understandable to ,since .However,I think potential risks should not be ignored.The most serious/obvious risk is that .In this sense, .To prevent the risk from becoming a reality one day,you/we should (or It is understandable to ,since .My advice is to ,because .If you want to ,you should .)
Yours sincerely
HanMeimei