Several recent studies have reported a gradual decline in sperm production
in men. Endocrine disrupters as well as lifestyle have been suggested as ri
sk factors. One lifestyle factor that may affect human fertility is driving
a vehicle for a prolonged period. Several authors have suggested that driv
ing position may increase the scrotal temperature, In order to validate thi
s hypothesis we conducted continuous monitoring of scrotal temperature in r
eal conditions, i.e, in men driving a car for a prolonged period, Nine volu
nteer men were asked to walk outside for 40 min and then to drive a car for
160 min. Scrotal temperatures were measured from thermocouples and values
recorded every 2 min on a portable data recorder. Scrotal temperature incre
ased significantly (P < 0.0001) in driving posture after 2 h of driving, re
aching a value 1.7-2.2 degrees C higher than that recorded while walking. T
his link between driving position and increased scrotal temperature indicat
es a potential exposure of male reproductive function to lifestyle factors.