One possible version:

Dear Jack,

I'm glad to hear from you again. The cartoon you came across shows a major concern about food safety in China. It is reported that over 70% of the hotpot restaurants are adding chemical additives to their hotpot to save time, reduce cost, and make the hotpot look more inviting. However, the effects of the chemical substances on people's health remains unknown and most people tend to believe that chemical addictives will do great harm to human body, even causing cancer in some cases. It is certain that strong measures should be taken to make sure hotpot is safe. Whoever adds harmful elements into the hotpot is a danger to society and should be severely punished. Otherwise, people in China may never have hotpot.

It is a great pity that I may not be able to treat you to a delicious hotpot when you come to visit me in China one day, isn't it?

Yours,

Li Hao