Boil in the bag kippers etc don't have holes in them.
I was looking at Ziploc bags which are BPA free but the company say's they are not for boil in the bag use, even though loads of people use them to cook food in.
I've looked at oven roasting bags and slow cooker liners, which look like they are made from the same plastic to me.
And there's the thing about plastics releasing estrogen into food, which apparently can happen with plastic milk bottles and other cold containers even even if they are BPA free.
I wonder what plastics sous-vide cooking uses, and whether that releases estrogen or other chemicals into grub?
