Salivary thiocyanate secretion during a fleet ballistic missile submarine patrol. 561.

Tobacco smoke products make up an undetermined amount of the atmospheric contaminants of a fleet ballistic missile submarine. A biological measurement of the degree of effective tobacco inhalation both in smokers and non-smokers would be a useful tool in environmental health studies. Salivary thiocyanate levels seemed promising as such a tool. Thirty volunteers were selected from a submarine crew: 14 smokers and 16 non-smokers. Saliva was collected by standard methods during refit and on patrol. Thiocyanate content was measured and relationships were sought with dietary, smoking and patrol factors. Strong positive relationships were found between the thiocyanate levels and smoking, but no significant changes were found in either smokers or non-smokers on patrol. No relationships were found with dietary factors or with the amount smoked. It is concluded that the atmospheric effects are not extreme enough to be detected by this biological method. SALIVARY THIOCYANATE SECRETION DURING A FLEET BALLISTIC MISSILE SUBMARINE PATROL The relationship of thiocyanate to basal metabolism and thyroid function has been of some interest to physiologists (1, 2). Thiocyanate seems to exert an inhibitory effect on the iodine "pump" of the thyroid gland increasing the clearing of iodine from the gland and reducing the iodine uptake. As an end result the basal metabolic rate is lowered. Thiocyanate occurs normally in about equal amounts in all body fluids with the exception of saliva. The normal values for serum thiocyanate are generally reported to be less than 1.0 mg/100 ml while the saliva contains up to 25 mg/100 ml. The source of this normally occurring thiocyanate is generally thought to be the cyanide from the metabolism of proteins, the ingestion of some cyanide containing vegetables and from the cyanide in tobacco smoke (3). Much concerning the physiological role of thiocyanate is unclear. It has been suggested that one role is the de-toxification of body cyanides. In the past, thiocyanate has been used therapeutically to control hypertension (3). It is still used occasionally in body fluid studies (4). The excretion of thiocyanate normally occurs in the urine and feces. The normally high levels of thiocyanate in saliva has led to some studies of its oral significance but no definite relationship with oral health has been demonstrated (5). A marked increase in salivary thiocyanate is seen in individuals who are heavy smokers (6, 7). An attempt has been made with some success by Densen and co-workers (7) to use salivary thiocyanate levels as an indicator for effective degree of tobacco smoke inhalation. They were able to demonstrate general expected relationship in groups as the subject individuals ceased and resumed smoking. It was impossible to control for dietary and other factors in their study. The fleet ballistic missile submarine environment would appear as quite a practical place for a study similar to that of Densen and co-workers for two reasons: One, the nature of the environment makes it possible to analyze for dietary and atmospheric factors; and two, from a practical standpoint the thiocyanate levels may lead to a better understanding of the effects of a closed, relatively smoke laden atmosphere. A study was therefore designed to study the salivary level of the thiocyanate ion with regard to four variables: Smoking, diurnal variation, diet, and atmosphere. By way of explanation, the "atmosphere" variable refers to a closed submarine versus an open submarine; in other words, "Will breathing tobacco smoke in a closed atmosphere result in increased salivary thiocyanates in nonsmokers?" MATERIALS AND METHODS Thirty volunteers were selected from the crew. There were 14 smokers and 16 nonsmokers. In all other respects the subjects were a random selection of volunteers. The saliva was collected as follows: The subjects were given a one-half stick of pure paraffin to chew and the first two "spits" were discarded. The following three "spits" were collected in a wide mouth receptacle and a 300 ul sample was placed in a microcentrifuge tube for thiocyanate analysis. In order to allow for diurnal variation collections were made before breakfast (0600-0800) and after the evening meal (1900-2100). The actual time was recorded at each of these collections. The collections were made for seven consecutive days during refit, during the second week of patrol, and during the last week of patrol. Each evening at bedtime during each collection period the subjects were given a mimeographed diet questionnaire. This was done to discover the foods ingested that day with particular emphasis on those foods known to contain cyanates such as cabbage, broccoli, cauliflower, turnips, radishes, garlic, horseradish, mustard, and almonds. Analyses were performed by a micro adaptation of the method described by Barker included in Clinical Laboratory Diagnosis (8). The data were analyzed factorially. The analyses of variance were concerned with the four variables stated in the introduction. RESULTS Thiocyanate secretion patterns are given for the thirty subjects in Table I. The "S" preceding the .subject number denotes that the individual is a smoker. All values are mean thioc3anate levels in milligrams per 100 milliliters plus or minus one standard error of the mean. Usually each mean value was based on 14 samples. It is of note that very few individuals showed any remarkable changes between collection periods. Subject "S07" did show a significant decrease in the second and third periods compared with the first (P < .01). This individual quit smoking after the first collection series. Subject 18 offered the possibly opposite observation having begun smoking after the first collection period. The differences in this case were not significant. In passing, it should be noted that the salivary thiocyanate levels in this group of subjects agree with previously reported studies. The secretion pattern as influenced by smoking and by the patrol are given in Table II, It is noted that there is a significant difference in the levels between smokers and non-smokers. No other comparisons are remarkable. The analysis of variance was used, Table III, to compartmentalize the effects of smoking and patrol effects on the thiocyanate levels. Only in the case of the smoking variable was the f ratio great enough to be considered statistically significant (P < .001). In other words, there were no significant effects of the patrol nor of interactions between patrol effects and the smoking variable. The diurnal factor is included in Table IV, and again the smoking variable accounts for the significant amount of variances. Dietary responses were used to study the relationship of cyanide containing foods and the salivary thiocyanate levels. The results are summarized in Table VI. It is apparent that no relationship was found. Table I Individual salivary hiocyanate level s at the var