work related medical problems

Does anyone have idea how i can build a case to show that my lower back injury is caused by my work?
I'm 23 years old and am unable to work because of pain, Currently I'm taking durogesic patch and that is barely helping for normal daily routine like getting up, dressing, washing...
The reason why i'm interested in pointing out that it's work related is because the people that I work(ed) with are also having back and shoulder problems (like 75% of them have problems, 2 of them also under 30y/o)
Now when one or two persons at work would have the same problem...   OK, could be bad luck
But 7 out of 10???
I work in the Food industry and we get exposed to --(repeated) lifting. --Vibrations, --Pushing and pulling carts at knee hight (550pounds), --Heat and humid air and cold (So Being hot and sweaty all day and then having to go into a (30°)cooling cel).

So... I'm just trying to build a case so my colleagues would have something to show when things should go bad with them as well.  Any thoughts/ideas welcome