I tend to be blunt when it comes to safety in general. My friends find this out pretty quickly. "Get your shoe out of the fire, I don't care how cold you are I don't want to have to leave camp to take you to the ER. I'm not kidding, get your foot out of the fire or I'll make you." Granted, that guy was drunk, but also I had a friend who never washed her fruits and vegetables before eating them. I'd suggested it nicely numerous times but she always told me they tasted fine. One day when she offered me an unwashed piece of fruit I told her no thanks, I'd rather not eat unwashed produce that might have been peed on by who knows what. She started washing her produce after that. The thing is, I let people know pretty early on in friendship that when it comes to safety I don't mince words, not because I want to be a jerk, but because I care about the person's well being. If I didn't, I'd stay quiet. I haven't lost any friends over it yet. In your situation, when she responded telling you that it was fine, she does it all the time, I'd have responded right then that if she wanted to risk her safety, so long as she's been informed, fine. That's her decision. But I'd have told her I wouldn't be eating at her house anymore. Again, my friends know right from the beginning that I'm blunt about such things, so it works for me.
Just because something has a duck bill doesn't mean it's a platypus. It might just be a duck.
Roger Miller: You can't roller skate in a buffalo heard, but you can be happy if you've a mind to.