I understand how this may be a little disconcerting to some. One expat friend we had in Angra actually refused to drink milk in Brazil because he could only buy it in a box and not refrigerated at that. Having been a quasi health conscious eater before we arrived here, I had met with the little square of milk before, but not as the only option available for purchase. If you think about it though, a carton is really only a glorified box. However, the semitransparent jug is a whole different beast. If that is the only way you’re used to getting your milk or straight from the cow, goat, whatever or glass bottles, you might have a bit of an adjustment period in Brazil. All of the stores I’ve been to (in Niteròi, Rio and Angra) sell milk only in these 1Liter boxes and they are in the aisles at room temperature. Once you get them home and open them you need to refrigerate them or they will go bad. Oh, and check for punctures and holes in the boxes before you buy them or you might find yourself with a full liter of spoiled milk once you’re ready to indulge ( we did this once). There are several different brands and they come with varying degrees of fat and fortification. Also, there’s soy milk if that’s more your style (also in a sort of box).
In closing, don’t be afraid of the box. It still does a body good.