The American workplace is grueling, stressful and surprisingly hostile. Concludes an in-depth study of 3,066 US workers by the Rand Corp., Harvard Medical School and the University of California, Los Angeles. I was surprised at how physically demanding jobs were, says lead author Nicole Maestas, a Harvard Medical School economist. Maestas wonders whether toxic working conditions are keeping Americans out of the labor force. The first-time survey of Americans ages 25-71 was carried out in 2015.