lasvt 'honeuroendocrtnologi '. ~.ol. 7, No. 2 3, pp. 97 99, 1982, Pergamon Press l i d . PrinEed in t.ireal Bnlain.

E D I T O R I A L

E N D O C R I N E A C T I V I T Y I N A I R T R A F F I C C O N T R O L L E R S

A T W O R K

THIS ISSUE contains a three-part report entitled Endocrine Activity In Air Traffic Controllers At Work by Rose, Jenkins, Hurst, Kreger, Barrett and Hall. These papers, impressive though they are in scope, are but a small part of a very much larger comprehensive study of air traffic controllers reported elsewhere (Rose et a1.,1978). The entire study is extensive indeed, involving 416 male controllers studied along a myriad of dimensions over a three-yr period. The author 's work already has brought forth a treasure-trove of data from which useful analyses have emerged. The present data may well be of even greater importance as a basis for future analyses and follow-up studies. For example, the psychoendocrine portion of the study involved continuous blood sampling from free-living subjects every 20 min for five-hr periods. There were 15,000 blood samples analysed. Such richness of information about humans in real work situations is increasingly hard to come by in an era of suspicion and legalism, and yet, extensive data must be obtained if we are to understand better the physiological and pathological processes occurring during the actualities of human life. In a similar vein, for example, the data amassed on military personnel in World War II are still being successfully mined by the National Research Council Veterans Follow-up Agency. Important discoveries are being made about the delayed effects of experiences as varied as exposure to cleaning fluids in 1944 or being a prisoner of war of the Japanese (Beebe, 1975). In yet another instance, the Framingham Study data remain of great utility in understanding the progression of illness in an aging population as follow-up information is obtained ad seriatim (Dawber, 1980). In a cognate field, the studies of Wiener, Thaler, Reiser and Mirsky, in which they noted the appearance of peptic ulcers in soldiers in basic training in relationship to the soldiers' psychological characteristics and their levels of pepsinogen, has remained a landmark study in the field of psychosomatic disease (Gottschalk et al., 1972). This ulcer study was not subject to attempts at independent verification early, and very likely could not be replicated today, if for no other reason than that the necessary permission to carry out the X-ray and other studies could not be obtained. We need to recognize that opportunities such as that afforded Rose et al. are rare and possibly unique within a given generation.

The state of the investigative art is captured in amber in studies of this sort. The up-to- date methods of Rose et al. represent a distinct advance over the crude, once-a-day determinations performed not so many years ago in an attempt to document changes in hormone concenfrations in free-living subjects. There is no doubt that, in turn someday in the future, their approach will be thought technically rudimentary. Before the data

Correspondence to: Dr. R. J. Arthur, Dean, University of Oregon School of Medicine, Portland, OR 97201, U.S.A.

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collection ever began, the investigators were cognizant of the necessity of repeated sampling and of measuring possible changes in hormone levels occasioned by such phenomena as venipuncture. In order to do this, they used indwelling catheters, the very existence of which reflects advances in petrochemistry, physics and applied biology. They were also able to rely on accurate methods of determining hormone levels such as radioimmunoassay, the development of which came as an outgrowth of advances in basic science. At the level of human intervention, the investigators were assisted by technicians skilled in the use of the catheter technique, rather than having to perform all manipulations themselves as might have been the case not long ago. All this speaks to how many significant advances in science and technology had to be made before a safe and apparently simple mechanism of obtaining many small samples of blood in an ambulatory subject became possible.

The investigators chose to study cortisol and growth hormone. Of course, there are thousands of bodily substances, the concentrations of which may well rise and fall in response to external demands of a psychosocial or physicochemical nature. Cortisol and growth hormone have the advantages of precision of measurement and a reasonable body of evidence as to their functional significance. If one wished to catch the moment-to- moment fluctuation in levels, however, and indeed, there must be moment- to-moment fluctuation as impulses in and from the central nervous system change the internal environment, no technique of sampling by quanta can adequately document these crucial yet often evanescent phases of change. The ability to do this kind of continuous monitoring, oxygen-gauge fashion, awaits a technology of the future. For the present, the Rose data are wonderfully dense and detailed. The authors were able to confirm again the diurnal variation of cortisol levels, with a decrease toward the afternoon hours. They also confirmed a dissociation between the cortisol and growth hormone rythms, with growth hormone rising in the afternoon rather than falling, as is the case with cortisol. They also showed that average or peak cortisol was not very consistent for any given individual from day to day. Because just looking at average endocrine values produced nothing exciting, the authors used a so called ' ipsative' (meaning, the same thing) technique, that is comparing one day for a subject with another day for the same subject. They studied their subjects on every sort of dimension from age to workload. Basically, however, the variables encompassed demographic and physical ones such as wt and blood pressure. They also obtained psychological inventories, both standard and special, on each subject. In addition, they attempted to delineate in a quantitative way each aspect of the actual job, for example in their concepts of base-load and man-work. None of the biological correlates, other than wt, were related to cortisol or growth hormone levels, nor were the ingestion of such substances as cigarettes, smoke, caffeine or alcohol related. Those men with the least health change showed a slight tendency to have increased average cortisol concentrations, as did those with more psychiatric symptomatology. A subgroup of men classified as ' responders ' did show cortisol increases concomitant with workload increases. Somewhat unexpectedly, the responders were rated by their peers as highly competent, and they themselves reported good job satisfaction. The correlations, definite but modest, do give rise to disquieting questions about our accepted ideas of the hypo tha l amic - p i tu i t a ry - adrenocorticoi system and its responsivity to adaption.

EDITORIAL 99

The f indings o f Rose et al. fit in very well with M a s o n ' s (1975) fo rmu la t i on abou t the impor t ance o f the psychologica l var iables o f novel ty , un fami l i a r i ty and chal lenge in the a rousa l o f p sychoendoc r ine systems, but they also suggest that there m a y be more to ad rena l a rousa l , f rom a p sychoendoc r ine poin t o f view, than mere novel ty . The f indings also speak to the impor t ance o f coping responses to pa r t i cu la r life s i tua t ions in expla in ing endocr ine a rousa l or non-a rousa l . F o r a var ie ty o f reasons , research has tended to concen t ra te on a relat ively small number o f h o r m o n e s and to conceptua l ize their regula t ion within ra ther s te reo typica l systems. Now that recent work offers evidence that h o r m o n e s occur much more widely in na ture than had been previous ly thought , for example , not only in ver tebra tes such as b i rds and fish, or in inver tebra tes such as insects, but even in bac te r i a (Roth et al., 1982), we necessar i ly will have to re th ink our theore t ica l f r amework in p s y c h o n e u r o e n d o c r i n o l o g y . No doub t , fu ture t echno logy will enable us to m o n i t o r ent ire a r rays o f substances and thus gain an app rec i a t i on o f subt le modu la t i ons occurr ing dur ing each m o m e n t in t ime. Meanwhi le , we look fo rward to fur ther analyses o f the air t ra f f ic cont ro l le rs da t a and to fo l low-up studies that will cont inue to make f rui t ful and cons t ruc t ive use o f this inva luab le mater ia l .

RANSOM J. ARTHUR Dean, Univers i ty o f Oregon School o f Medic ine

REFERENCES BEEaE, G. W. (1975) Follow-up studies of World War II and Korean war prisoners il. Morbidity, disability and

maladjustment. Am. J. Epidem. 101,400-422. DAWBER, T. R. (1980) The Framingham Study. Harvard University Press, Cambridge, Massachusetts. GOTTSCHALK, L. A., KNAPP, P. H., REISER, M. F., SAPIRA, J. D. & SCHAPIRO, A. P. (Eds.) 0972)

Psychosomatic Classics, pp. 25 - 35. Karger, Basel. MASON, J. W. 0975) A historical view of the stress field: part one J. Hum. Stress !, 6 - 12. ROSE, R. M., JENKINS, C. D. & HURST, M. W. 0978) Air Traffic Controller Health Change Study. Boston

University School of Medicine, Boston, Massachusetts. ROTH, J., LEROITH, D., SHILOACH, J., ROSENZWEIG, J. L., LESNIAK, M. A., & HAVRANKOVA, J. (1982) the

evolutionary origins of hormones, neurotransmitters, and other extraceUular chemical messengers. New Engl. J. Med. 306, 523- 527.