Alarmingly high levels of thyroid hormones pump through the systems of South Dakota residents. Investigators study one large family whose 12-year-old son did not get sick. The tip-off: he's a vegetarian. It seems that when drug companies started manufacturing synthetic thyroid hormones, they stopped buying thyroid tissue from butchers who did not trim these parts, but rather sold them as 'extra lean beef.' The outcome: the U.S. Dept. of Agriculture bans meat plants from using meat in or near the gullet for beef and pork products. Originally aired as Season 1, Episode 11. (thetvdb.com)