Actually, the chart uses a measure of radiation, a Sievert, that is normalized to effects of ionizing radiation on the body. So it does not matter that the sources of radiation are different, or that some are beta emitters and others are gamma emitters--they are normalized.
The chart is not accurate or relevant to this discussion.
It makes the same mistake that nuclear industry dosimetry calculations make - it does not account for the element and type of exposure.
Potassium emits energy at a higher energy than Uranium therefore formulas typically used comparing bananas to uranium indicate - if the numbers are right, that Potassium is more harmful (higher resulting calculated “dose”). But this is not medically true.
According to an online EPA source, counter intuitively, the human body is relatively transparent to high energy radiation (like that of bananas) and is more seriously harmed by lower energy provided by uranium. According to a lecture I attended, the theory explaining this behavior is that high energy radiation passes quickly through human cells one time, in this example lets say it cuts through the strand of DNA one time and continues on through neighboring cells and out of the body. The body must repair one break in that cell’s DNA and let’s say one break to many other body cell’s DNA.
Contrast this with the lower energy transmission of Uranium which can pass through cells at a slower rate and essentially bounce off of cellular material and atoms in a manner that results in ricochet with damage done each time the energy bounces off material in the cell or body and passes through DNA more often, causing more breaks, requiring more repair.
The chart is poor in that anytime you get comparisons which align bananas, sleeping next to someone, and air travel with comparisons to medical use and nuclear disasters like Fukushima and Chernobyl, distortion is at work. They are not the same.
None of us knows what our current dose (cumulative over the span of our lives) is at the prescient moment, but we can say adding any additional radiation to the environment (not the medical office)through incompetent management (the nuke industry) raises the level of risk of human illness and that risk can remain elevated for decades (Cesium) or thousands of years (Uranium).
Our society investigated and rejected Carbon Tetrachloride for use in dry cleaning once it was discovered to contribute to cancer risk. Yet because nuclear power is defended by government, we get charts suggesting that we should look at radiation doses from one time exposures like chest x-rays and somehow relate them to the dosage of exposure to residents of Fukushima over a specific period of time (Tokyo) when those are unrelated to the chronic exposure that fits reality - residents of Fukushima, Tokyo and the rest of Japan (Government maps indicate that the far reaches of the island nation received fallout albeit far smaller amounts that regions closer to the nuke plant the nuke plants)will be chronically exposed to the unconstrained wastes of this ongoing nuclear disaster for the rest of their lives. They will receive combination doses in food, water and air for the foreseeable future. No one has a chart for that.
Nuclear waste remains in the land, the produce, the drinking water etc. and will continue to do so for many lifetimes - where is that on the chart? Nope - the chart is deceptive. It normalizes things that are not normal.
According to the EPA, evidence supports the Linear No Threshold Model, which proposes that even small amounts of exposure increase the chance of resulting illness (a small amount, and these exposures are cumulative).
https://www.epa.gov/radiation/radiation-health-effects
Certainly the BEIR reports, (state of the art research studying effects of radiation on human health) year after year report that small amounts of exposure to ionizing radiation contribute a small amount to illness risk, and that large exposure contributes to large illness risk.
http://dels.nas.edu/resources/static-assets/materials-based-on-reports/reports-in-brief/beir_vii_final.pdf
So the public has a right to question the increased risks it faces when Fukushima loses control of 3 nuclear fuel cores. And the chart is deceptive in that it poses an unrealistic view of radiation effects.