If the drink is hot enough it could melt the straw. Then you could inhale molten plastic which could be bad for your lungs. Otherwise there could be BPA given from the melting plastic
There is a risk of carcinogenic toxins entering your system if you use a straw with your hot drink unless you have a full plastic straw which does not melt, since plastic contains carcinogenic substances.
I like to drink coffee while I'm driving, and using a straw allows me never to take my eyes off the road. I learned this from friends in law enforcement.
Like all plastic products, plastic straws contain chemicals. When heated, some of the chemicals are released into your drink which you will then injest. However, the chemicals are not highly concentrated enough to harm you.
There is a possibility of sipping a drink that is too hot, and then spraying it all over when I react to the burn. That could cause further burns, clothing stains, and embarrassment.
prior to anaerobic exercise i used a plastic straw to stir a hot mocha. i then vommited (b4 n after shower) noticing what seemed like milk skin. i used hot water and realised i had drank melted plastic. - probz got brain damage cuz im feelin' kinda lame. awesome.