English: The original line starting at 200 at 4 hours was published in 1975. When the NAC study was begun in 1976 the FDA required a line that was 25% below the original line. The study line which is now referred to as the treatment line was created starting at 150 at 4 hours and is the usual line used in the United States to determine treatment of acetaminophen (paracetamol) overdose.