Absolutely Not..! Giving blowjob and drinking semen isn't risky or harmful unless your boyfriend has got some serious STD issues. If he is clean and healthy.. I don't think you will suffer any problem. Discussing about Sex problems and diseases with your boyfriend can be a great idea too. I mean you can get more frank and open to each other and even can get to know about each other really good. So do ask your boyfriend if he has got some serious disease or infection and do strictly DECLINE to give him a blowjob if he is prone to some risk.
Wish you luck
Wish you luck