In an attempt to examine the hypothesis of whether physical activity c
auses increased uptake of lead in humans, blood lead levels were measu
red in 231 individuals. Included in the study were subjects who lived
in Northern Italy and who practiced noncompetitive running in urban ar
eas or along the countryside. The mean values (1.25 +/- 0.27 mu mol/l)
measured in a group of 28 runners who trained at tracks and on roads
of a large town, characterized by heavy traffic and high atmospheric l
ead levels, were slightly higher than those recorded in a group of 10
runners of the same town who trained mostly in a rural environment (0.
99 +/- 0.29 mu mol/l) and, with a striking and significant difference,
in a comparable group of 182 nonrunners (0.46 +/- 0.22 mu mol/l). The
se background figures were similar to those found in 11 runners who li
ved in a smaller, less polluted urban area who trained in country toad
s (0.40 +/- 0.11 mu mol/l). Blood lead levels were correlated signific
antly with the intensity and frequency of the running practice and wer
e unrelated to smoking habits.