is it illegal to not give breaks at work?

my boyfriend works outside building grain bins 12 hours a day and today he only got one break! it was plus 40 and hes sick now. im pretty upset the break was to wait and see if the boss wanted them to continue to work even tho there was a heat warning... i really want him to find another job the boss seems really sketchy. his friend also cut himself pretty bad because something didnt get hooked up right and on the way to the hospital the boss told him to say it happened at a Friends house..