New moves to test pregnant women for smoking by measuring carbon monoxide on their breath. How helpful are lifestyle targets like 10 portions of fruit and veg or 10, 000 steps a day? The incidence of thyroid cancer has tripled in 40 years, but many of the tumours picked up are on scans for something else and may never have caused harm. Mark Porter debates the issues. Plus this week's uncertainty question for Margaret McCartney and Carl Heneghan, to floss or not to floss?