[Trends in urinary analgesic excretion in a cohort observed from 1968 to 1975].

From 1968 to 1972 and in 1975 (provisional results) urine samples collected on three days per year were examined by photometer for N-acetyl-p-aminophenol (=NAPAP, main metabolite of phenacetin) and for salicylates in the same population. It consists of 1200 women born from 1918 to 1937 whose majority works in 80 enterprises of Northwestern Switzerland. In 1968 half of the women showed regular intake of phenacetin containing analgesics (=study group) in contrast to the other half that did not (=control group). Excretion of salicylates was no criterion for grouping. Between 1968 and 1972 the total of women positive for NAPAP in urine decreased from 50% to 35%. The decrease concerns almost exclusively women positive for NAPAP on one or two days, whereas the number of women positive on all three days remained stable. At the same time the total number of women positive for salicylates decreased too. Possible reasons for the decreasing tendency of analgesics intake are mentioned. The much more frequent excretion of salicylates in the study group in contrast to the controls is probably due to the intake of combined analgesics. The provisional results of 1975 are in accordance to those observed previously.