Endocrine activity in air traffic controllers at work. I. Characterization of cortisol and growth hormone levels during the day

This is the first in a series of three reports on repeated endocrine studies in the working environment for a group of 416 air traffic controllers. Twenty-minute integrated concentrations for plasma cortisol and human growth hormone across five-hr work periods are described and compared with a selection of studies of normal males reported in the literature. On average, across three repeated studies, controllers were secreting more cortisol and less growth hormone than the most comparable group of normal males. Cortisol and growth hormone levels were not appreciably related, and both hormones showed a lack of consistency across repeated studies in terms of average level or measures of episodic secretory activity. Small increases in cortisol secretion in response to venipuncture were apparent in some controllers during the morning hours; on the other hand, no growth hormone responses were evident. Neither hormone showed decreased secretion with repeated blood collections. Relationships between hormone secretion and the work environment, which possibly explain the lack of hormone consistency across time, will be examined in the second report.