Although the epidemiologic evidence is not convincing, a number of studies indicate that those exposed to dynamic loads may have increased risk to low-back disorders. A review of the available evidence suggests that chronic low-back pain relates to disc degeneration and that this in turn may be accelerated by mechanical failure in the region of the end-plate and subchondral bone or in the annulus. Two hypotheses are proposed to relate fatigue induced failure of vertebral tissues to disc degeneration. The extent of dynamic stresses on the vertebral motion segment arising from transport are investigated, and the results indicate that fatigue induced failure is a distinct possibility. The implications of these suggestions for environmental health protection are briefly discussed.