Lab tech, moving 3 gallon buckets (weighing 7-10 lbs) from stacked on a pallet, to a pull cart. Some buckets that were stacked 5-6 high fell over onto him as he was kneeling. Buckets hit the employee in the head (wearing hardhat). Headache resulted. No other injuries. Became a Lost Work Incident on August 15th (Dr. gave 10 Days Off).