Exercise human exposure studies during

An experimental human exposure study titled Tetrachloroethylene Development of a biologic standard for the industrial worker by breath analysis, completed by Stewart and colleagues, was first published by NIOSH in 1974. This publication can now be obtained from the National Technical Information Service (NTIS) with a 1981 date, and is cited as Stewart et al. (1981) throughout this Profile. In this study, four male volunteers were sequentially exposed to 0, 20, 100, or 150 ppm tetrachloroethylene vapor for 7.5 hours/day, 5 days/week (Stewart et al. 1981). The men were exposed to each concentration for 1 week. Once each week, pulmonary function was assessed at both rest and during two levels of exercise with forced maximum expiratory flow measurements, while alveolar-capillary gas exchange was measured by single breath carbon monoxide diffusion. The exposures to tetrachloroethylene at these vapor concentrations and time intervals had no effect on the pulmonary function measurements. 

In addition to field studies, controlled human exposures to PERC have been reported. In this type of studies, subjects were exposed to various constant levels of PERC for different lengths of time with or without exercise. Samples of blood, exhaled air and urine were collected according to a variety of schedules both during exposure and for varying lengths... 

Data describing the interaction of 2-butoxyethanol or 2-butoxyethanol acetate with other chemicals are scarce. Simulations of human pharmacokinetics of co-exposure to ethanol (0.1% in the blood) during an 8-hour exposure to 20 ppm 2-butoxyethanol with no exercise predict that the arterial levels of 2-butoxyethanol will be elevated as a result of a decrease in elimination rate (Johanson 1986, 1991a Johanson and Naslund 1988). Because the increase in 2-butoxyethanol is due to decreased elimination and not increased uptake, the rise and fall of blood concentrations of 2-butoxyethanol are slower in the ethanol co-administration model than in the increased workload model. A study in rats indicated that co-administration of ethanol and 2-butoxyethanol resulted in a higher blood level and a prolonged blood... 

In this study, central nervous system function was evaluated in multiple tests including perceptual speed, simple reaction time, short-term memory, numerical ability, and manual dexterity. A lowest-observed- adverse-effect level (LOAEL) was seen in the same study when humans were exposed to 4,000 mg/m for 50 minutes. The subjects had a prolonged simple reaction time compared to control results in the same volunteers during a non-exposure period. It should be noted that because of practical constraints, these tests were conducted on volunteers at rest and that parallel pharmacokinetic studies have demonstrated greater uptake during exercise (Astrand et al. 1975). 

There are strong plausible hypotheses for the relation between exposure to tobacco and vascular disease. In animal and human studies, endothelial injury has been associated with carbon monoxide and nicotine. In contrast to healthy individuals, those with ischemic heart disease are affected by carbon monoxide during submaximal exercise, in part... 

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