Changing cancer risk pattern among Finnish hairdressers

A cohort of 3637 female and 168 male hair-dressers in Finland was followed up for cancer through the Finnish Cancer Registry in 1970-1987. Compared with the total population, the women had a significantly elevated risk (standardized incidence ratio 1.7) during the first third of the observation period, but not thereafter. For the total follow-up period, the relative risks were highest for nonmelanoma skin cancer (2.0), lung cancer (1.7), ovarian cancer (1.6), cervical cancer (1.5), and cancer of the pancreas (1.5); only the risk of ovarian cancer was statistically significant. A decrease in relative risk with time was observed for many primary sites, e.g., pancreas, cervix uteri, central nervous system, and thyroid. The opposite was true for lung and skin: An increased risk was found only in 1982-1987. The excess was most prominent in the oldest age groups with the longest time span since the first employment as a hairdresser. Among men, too, the general cancer risk was highest (1.6) during the first third of the observation period. An excess of cancers of the lung and the pancreas was observed. The small numbers, however, did not allow any further conclusions. The changes in the cancer risk pattern over time may be associated with changes in working conditions in hairdressing salons.