Lancet 1999 (Dec 4); 354 (9194): 1974
Negrini S, Carabalona R, Sibilla P
"34.8% of schoolchildren carry more than 30% of their bodyweight at least once a week"
Repetitive loading on the spine is known to be a risk factor for lower back pain. Stefano Negrini and colleagues investigated the weight of backpacks carried by 237 children aged 1112 years from a school in Milan, Italy, for 3 weeks. The median average load that the children carried was 9·3 kg, and the median maximum load was 11·5 kg, ranging up to 16·3 kg.
No limits for the weight of backpacks in schools have been established, but these weights are beyond the allowed (corrected for bodyweight) load limits for adults by labour law in Italy. Rates of lower back pain in children are increasing, and these results suggest that a reduction in backpack weight is advisable.