This study examined the extent to which the potentially toxic lead particulates emitted from motor vehicles are absorbed by competitive cyclists. A time trial (n = 5), a road race (n = 5), and a sedentary control group (n = 5) were examined with respect to blood lead (PbB) levels. In the two cycling groups, the PbB levels were measured before and after (1) a time trial (80 km) held on a dual carriageway; and (2) a road race (120 km) which took place in a rural area. Mean (+/- SE) resting PbB levels for the sedentary subjects, time trialists, and road racers were 0.442 +/- 0.041, 0.490 +/- 0.111 and 0.384 +/- 0.061 mumol l-1 respectively (p > 0.05). Mean post-race PbB levels of the time trialists (0.528 +/- 0.046 mumol l-1) and road racers (0.346 +/- 0.024 mumol l-1) did not differ significantly from the pre-race levels (p > 0.05). However, after their respective races, the mean PbB level of the time trialists was higher than that of the road racers (p < 0.05). Ninety minutes of cycling (70% VO2 max) in a laboratory containing approximately 1 microgram m3 of airborne lead did not affect blood lead levels. All PbB levels compiled with EC regulations regarding lead exposure. Despite a positive relationship between the amount of training and the PbB levels (r = 0.64, p < 0.05), competitive cyclists did not evidence abnormal levels of lead absorption. Time trialing on dual carriageways was associated with higher PbB levels than road racing.(ABSTRACT TRUNCATED AT 250 WORDS)