Working with the chart, to reach the lowest dose clearly linked to cancer (100mSv) minus background radiation for a year (4 mSv, so to get 96 mSv), you can find

Working with the chart, to reach the lowest dose clearly linked to cancer (100mSv) minus background radiation for a year (4 mSv, so to get 96 mSv), you can find some silly permutations of that to get to 100mSv: Spend a year in the Fukushima Exclusion zone (26mSv) plus 10 Chest CT scans Spend a year in the Fukushima Exclusion zone, then take the max dose for a US radiation worker and two chest CT scans. The whole green area of the chart (75 mSv) plus taking a dose at the northwest edge of the Fukushima exclusion zone puts you 19 mSv over the limit. So lay off a couple of CT scans and visits to Chernobyl, Three Mile Island, and Fukushima and you'd be beneath the limit clearly linked to cancer. Get 5000 chest X-Rays 250 mammograms Eat a million bananas This silly exercise at least convinces me to worry less about X-rays, plane flights, and eating bananas. It would be nice if XKCD had the dose that takes your cancer risk above certain thresholds like 1/million, 1/1000, 1/100, etc. It would also be nice if the public calmed down about radiation.