Just imagine.......
Dr. Bodger - "Ah, hello Mr Mars, thankyou for coming back to see me albeit that I'm afraid that I do have some rather grave news to report. You see, we've done some research and, although the exact cause is not yet known, we think the most probable cause - albeit based on circumstantial evidence and suggested potential - is an excessive level of infection from the compo virus and accordingly we think it prudent to chop off yer hands !"
Thus, w.r.t. 'most probable' - should really read, "we don't actually know what, for certain, is causing this".
Then w.r.t. 'circumstantial evidence suggested potential......' what the UK CAA are really saying is that is that they have no rock solid evidence or hard facts to support their findings.
Finally, w.r.t. 'safe bar drinking and reading the label'.... but surely that then takes all the fun & risk out of it ?!