Unfortune slip and lack of the evidences

My boyfreind had an accident at work. He was supposed to carry some parcels as usually to the delivery car. There was some liquid on the pavment and he slipped over. He was not informed that inside th parcels were dangerous chemicals. He hit his head against the kerbstone and the liquid from the parcel spilled. The vapours of the chemicals caused sereoud burns of the airway. He almost died.

His company made the raport in which they put that he was not to carry that parcel to the car. How to get evidences? His collegues are on his faveour.. Is it enaugh if they confirm his version? I don't want to aks them to risk their jobs if there is no way to help him...  Thanks for your opinion.