We studied sunlight exposure from outdoor work in relation to cancer, using
data from 323,860 men participating in an occupational health service prog
ram of the Swedish construction industry. An experienced industrial hygieni
st assessed the exposure for 200 job tasks. We estimated relative risks (RR
s) adjusted for age, smoking, and magnetic field exposure. There was an inc
reased RR in the high-exposure group for myeloid leukemia [RR = 2.0, 95% co
nfidence interval (95% CI) = 1.1-3.6] and lymphocytic leukemia (RR = 1.7, 9
5% CI = 0.9-3.2). For non-Hodgkin's lymphoma there was a 30% increase in ri
sk in the high-exposure group (95% CI = 0.9-1.9). There was no increased ri
sk of malignant melanoma, except for tumors of the head, face, and neck in
the high-exposure group (RR = 2.0, 95% CI = 0.8-5.2), and we also found an
increased risk for malignant melanoma of the eye in this group (RR = 3.4, 9
5% CI = 1.1-10.5). Outdoor workers had no increased risk of nonmelanoma ski
n cancer. Nevertheless, the RR for lip cancer (squamous cell carcinoma) amo
ng the high-exposure group was estimated at 1.8 (95% CI = 0.8-3.7). Among o
ther sites, an increased risk of stomach cancer was suggested in this group
(RR = 1.4, 95% CI = 1.0-1.9). The results for lymphoma, leukemia, and poss
ibly also for stomach cancer might reflect a suppression of the immune syst
em from ultraviolet light in outdoor workers.