[heynk]

I believed they are scaled equally. Each 'step' from the middle indicates an increase or decrease in risk by a factor of 2. If you're at 0.5, you're half as likely to get cancer; 2, twice as likely. 0.1 is 10x less risk, 10 is 10x more risk.

The graph was also created by Vox and includes the words 'cause' and 'prevent' for exaggeration, but the individual studies mostly imply correlation.