More than 40 million students carry school backpacks (Teaching Elementary Physical Health, March 1999).
  A 1999 study by Simmons College (Boston) professor Dr. Shelly Goodgold, Sc.D found that more than half of children in a study regularly carried more than the recommended 15% of their body weight in their school backpacks.
  The U.S. Consumer Product Safety Commission estimated that more than 3,300 children, aged 5-14 years, were treated in emergency rooms for injuries related to backpacks in 1998; these numbers do not include students who went to family physicians or orthopedists.
  A study by Auburn University researchers (Anniston, Alabama, Pascoe, et al) stated the most common symptom reported from backpack use is "rucksack palsy." This condition results when pressure put on the nerve in the shoulder causes numbness in the hands, muscle wasting, and in extreme cases, nerve damage (Journal Ergonomics, vol. 40, #6, 1997).
  58% of orthopedists polled in 1999 in Chicago and Wilmington, Delaware, reported treating children with back or shoulder pain attributable to carrying backpacks.