Having just acquired a second iPhone I thought I'd test this out and you can indeed see your WhatsApp profile pic but that's all, if your worried about it then change your pic, its easily done but its a shame you can't just confirm or deny access to it so maybe its safer not to have at all..
For anyone not aware, WhatsApp is a free app
On a similar theme, those using iOS and into iMessage once your in a group message that's it, you can't opt out and you can't stop messages/pictures unless you turn off iMessage itself!
It's a nightmare once your caught up in it whether its your main iPhone or your 2nd iPhone and/or iPad/iPod
In America you can leave group message but 2 years on in this country we still can't
And, btw you don't have to join a group to be put in one, but once someone has your number they can put you in a group you just can't leave....
Just be carefully who you give your number and your email (iPad and iPod use your email) out to