Carbon monoxide, carbon disulfide, lead and cadmium--four examples of occupational toxic agents linked to cardiovascular disease.

A variety of industrial agents to which large segments of the population are exposed have been linked to the development of cardiovascular disease. These toxic agents, which include carbon monoxide, carbon disulphide, lead, and cadmium, are produced by a wide variety of industrial processes and so are ubiquitous in the modern industrial environment. Although the mechanisms by which such toxins may contribute to cardiovascular disease are not well defined, there are at least four possible theories that have received clinical and experimental support. The postulated mechanisms by which such toxins may play a role in vascular disease are: (1) an increase in blood pressure; (2) an increase in the levels of blood cholesterol and/or an induction of lipid accumulation in vessel walls; (3) an induction of a lipid peroxidation process thereby increasing the tendency of blood clotting; and (4) a promotion of a mutation in the arterial cell wall.

Chronohygienic and chronosocial aspects of industrial accidents.

A series of 2,772 accidents has been analyzed in two plants. The following aspects were considered: 1) environmental circumstances, 2) accident causes as given by witnesses or victims, and 3) time of day. Activity of the plants or particular groups of workers was assessed by supervisors on a 10-point scale. A circadian rhythm of accidents has been shown. It was determined to be governed by the interrelationships between the following endogenous and exogenous rhythmic factors: human factors, such as fatigue and circadian fluctuation of biological functions; and multiple hygienic and social components, which either promote human performance or suppress it, e.g., high environmental temperature, overcrowding, and noise. The rate of accidents depends on the particular combinations of these factors, all of which change around the clock. In both plants, the circadian rhythm of accidents was approximately parallel to the circadian rhythm of activity of the plant as a whole rather than to the activity of shift workers only, with a peak around 1100 hr. The lowest number of accidents was noted during night shifts; some increase was observed after midnight, however, in spite of the lowest level of plant activity at that time.

Some problems of night and shift work: Is the physiological cost of long-lasting standard work the same at night as in daytime?

Physiological reactions to long-lasting physical work performed at different times of day were measured in 20 healthy men. Circadian variations in physiologic variables have been shown which indicated higher physiological cost, of night work. The conclusions providing the base for establishing the criteria and guiding principles for shift work are discussed.

Influence of oral glucose load upon blood glucose level in relation to the time of day.

Blood glucose levels were estimated at different times of day in fasted rats and after 30, 60,90 and 120 min, since oral glucose load. Circadian variations in basal glucose levels and in the levels after glucose load were observed with the highest values noted between 11 a.m. and 7 p.m., and the lowest ones about midnight. These variations were most prominent when the measurements were performed 60 min after glucose load. Circadian variation in glucose tolerance was also revealed with the best tolerance at about midnight while the worst one was noted at noon and in the afternoon.

Influence of long-lasting physical work upon mental and psychomotor performance in relation to the time of day.

Twenty three women and 20 men (19--27 year old) were tested at different time of day using battery of psychological tests. All subjects were tested every 2 hours continuously for many hours. Between consecutive tests they worked on a bicycle ergometer (series A) or rested in sitting position (series B). The influence of three following factors upon performance level was considered: circadian fluctuations, duration of the experiment, and physical effort preceding testing. Positive influence of physical effort has been shown in psychomotor tests and negative one in mental tests which was especially pronounced at night or in the morning after night work.

[Dietary pattern of workers employed in a 3-shift system]. / Sposób zywienia robotników zatrudnionych w systemie trójzmianowym (badania pilotazowe).

The studies were performed among 105 workers aged 19 to 30 years, working in a 3-shift-system for at least one year. A questionnaire method of examination was used. Each worker was asked about his usual frequency of meals, sleep time and life routine while working on different shifts, as well as about the consumption of food in the last 24 hours. Usually, regardless of the period of working shift, workers consumed few number 57 meals. Meals during the working time were eaten mostly by morning-shift workers and very rarely by night-shift workers. Comparing calorific values of the meals consumed prior to the working hours at different time of shift work it has been shown that the meals consumed before night shift had the highest values, whereas the meals consumed prior to the morning shift had the lowest values. Generally, the meals consumed by shift workers did not vary and involved a large percentage of meat products, and fats, and too little percentage of vegetables, fruit, milk and dairy products. The food consumed by the workers under examinination contained mainly fats, protein and relatively little carbohydrates and ascorbic acid. Most of the workers preferred morning shift although sleep time was longest in case of afternoon shift. Complaints typical of the night shift included great fatigue and sleepiness. The sleep time was the shortest in case of this shift and sometimes it hardly amounted to 3 hours per day. The obtained results may be used for an elaboration of the lines of most suitably arranged meals schedule for shift and night workers.

Physiological and clinical aspects of circadian variations in glucose tolerance.

Significance of the circadian periodicity in glucose tolerance has been presented from physiological and clinical points of view in mechanisms responsible for this periodicity of which afternoon glucose intolerance is most evident. In healthy subjects, circadian fluctuations in insulin secretion and in sensitivity to insulin at tissue level are dominating. Circadian oscillations in insulin response to a glycemic stimulus as well as inherent periodicity in activity of the beta cells have been demonstrated by many authors.