PHP PDO::bindParam() data types.. how does it work?

I'm wondering what the declaration of the data type in bindParam() (or bindValue()) is used for... I mean, I thought that if I define an integer argument (PDO::PARAM_INT), the argument must be converted to an integer, something like $delete->bindParam(1, $kill, PDO::PARAM_INT); // should work like $delete->bindParam(1, (int)$kill); or at least throw an error if the argument is not of the declared