from what i remember it was 25kg, but this of course depends on the individual,..i.e a 6ft 16 stone rugby player could lift more than a 9 stone woman....
I did a health and safety course but cant remember a lot about it, but this stuck in my head...
TILE or LITE
It depends on the individual but the HSE recommend NO MORE than 25kg for a fit healthy guy (20 kg for a woman) for a weight held close to your body etc etc but it is up to the individual to decide if that amount is too much - NOT their boss ! Zacmaster's link is the one to read.