Exhaled air measurement

The nitrogen washout data consist of F, the fraction of nitrogen in exhaled air, measured as a discrete function of time after shifting to an 80-20 He-02 breathing mixture. When plotted as log F vs. time, the data fall along one line. Only the first one or two data points are above this best line. These presumably are caused by pulmonary and breathing loop dead spaces and are neglected hereafter. 

Retention of styrene was studied in a chamber setting where healthy males were exposed to either constant or fluctuating air concentrations of styrene. A computer-controlled system was used to generate time-varying air concentrations over 4-5 hrs with a mean air concentration of 50 ppm. End-exhaled air measurements taken throughout the... 

Spirometry A test method used to evaluate lung function that measures volume of exhaled air passing through a tube during a given time. 

FIGURE 20 Rate of metabolism of PCL and its metabolites, determined from measurement of carbon-14 in the excreta and exhaled air of rats after implantation (s.c.) of the low molecular weight polymer. (From Ref. 53.)... 

In the granite and alum shale areas, exhalation measurements above the ground were well correlated with the indoor air measurements. In the esker area, the exhalation rates were normal, and the high indoor Rn-222 concentrations here are believed to be caused by convective flew due to underpresure in the houses. (Stranden et al, 1985). 

The absorption of inhaled -hexane has been investigated in six healthy male volunteers (Veulemans et al. 1982). Three different trials were performed on each volunteer 4-hour exposure at 102 ppm -hexane 4-hour exposure at 204 ppm, and exposure during exercise on a stationary bicycle ergometer at 102 ppm. Each trial was done at least two weeks apart. Lung clearance (from alveolar air to blood) and retention were calculated from -hexane concentrations in inhaled and expired air. After exposure, /7-hcxane in exhaled air was measured for up to 4 hours to determine respiratory elimination. Retention of -hexane (calculated from lung clearance and respiratory minute volume) was approximately 20-25%... 

Approximately 10-20% of -hexane absorbed by inhalation is excreted unchanged in exhaled air the remainder is metabolized. Metabolism takes place via mixed-function oxidase reactions in the liver. In a study in which metabolites were measured in workers exposed to 77-hexane (Perbellini et al. 1981), mean concentrations of 77-hexane metabolites in urine were 2,5-hexanedione, 5.4 mg/L 2,5-dimethylfuran,... 

Toxicokinetic data can also be used to make informed decisions on testing of chemical substances. In specific circumstances, valid toxicokinetic data may be used to support a decision to omit testing for systemic effects, e.g., in cases where the toxicokinetic data provide sufficient evidence that a substance is not absorbed and therefore not systemically available, i.e., no plasma/blood concentrations were measurable and no parent compound or metabolites could be detected in urine, bile, or exhaled air. For example, in vivo testing for mutagenicity, reproductive toxicity, or carcinogenicity may be omitted if toxicokinetic data or other data indicate a lack of systemic availability. 

Several very sensitive and specific tests can detect carbon tetrachloride in exposed persons. The most convenient way is simply to measure carbon tetrachloride in exhaled air, but carbon tetrachloride can also be measured in blood, fat, or other tissues. Because special equipment is needed, these tests are not routinely performed in doctors offices but your doctor can refer you to where you can obtain such a test. Although these tests can show that a person has been exposed to carbon tetrachloride, the test results cannot be used to reliably predict whether any bad health effects might result. Because carbon tetrachloride leaves the body fairly quickly, these methods are best suited to detecting exposures that have occurred within the last several days. Further information on how carbon tetrachloride can be measured in exposed humans is given in Chapter 6. 

Response of the sensors to exhaled air was registered after an overnight fast of the subjects in one-minute exposition mode. The measuring unit was controlled before a measurement cycle by test recording of several responses to an action of exhaled air of the investigator. 

The acute interaction with ethanol was studied by oral administration of toluene as a 2 mg/min infusion for 3 h through a feeding tube into the stomach (Baelum et al., 1993). The infusion was chosen such that the exposure level was similar to inhalation of approximately 200 mg/m3 in combination with light exercise (50 W). Toluene was measured in exhaled air to monitor the toluene concentration in alveolar arterial blood. When ethanol was co-administered orally at a dose of 0.32 g/kg bw, a pronounced increase in the alveolar toluene concentration occurred, from 0.07 (range, 0.00-0.12) without ethanol to 74 (range, 60-93) mg/ni with ethanol. The rate of urinary excretion of the hippurate was reduced by ethanol, but otherwise little affected. Excretion of ortAo-cresol... 

Exposure to chlorobenzene can be determined by measuring the chemical or its metabolite in urine, exhaled air, blood, and body fat. Tests are not routinely available at the doctor s office. Specific tests are available that can determine if exposure is currently occurring or has occurred very recently, but not whether exposure occurred in the past. Further, levels in the various media stated above do not predict adverse health effects. Additional information on how chlorobenzene can be measured in exposed humans is given in Chapters 2 and 6. 

Levels of chlorobenzene and its metabolites have been measured in blood, urine, and exhaled air however, no studies were located linking any level of chlorobenzene in humans with a biological effect. Levels ranging from 0.05 to 17 ng/L were detected in the blood and 25 to 120 pg/L in the urine of residents living near a former toxic chemical dump, while trace amounts were found in exhaled air (Barkley et al. 1980). 

The lines in Fig. 7.4 are the results of theoretical calculations, using models of the respiratory tract (Yu Diu, 1982). The points are measurements with radioactive aerosols. Numerous other determinations of fractional deposition in the whole tract have been made, using non-radioactive methods to count the number of particles in the inhaled and exhaled air (Heyder et al., 1986 Schiller et al., 1988). Fractional deposition is least for particles of about 0.2 to 0.5 m diameter. Table 7.1 shows that the combined effect of sedimentation and Brownian motion is then at a minimum. 

In a basal metabolism measurement timed at exactly 6 minutes, a patient exhaled 52.5 L of air, measured over water at 20°C. The vapor pressure of water at 20°C is 17.5 torn The barometric pressure was 750 torn The exhaled air analyzed at 16.75 volume % oxygen, and the inhaled air at 20.32 volume % oxygen (both on a dry basis). Neglecting any solubility of the gases in water and any difference in total volumes of inhaled and exhaled air, calculate the rate of oxygen consumption by the patient in cm3 (S.T.P.) per minute. 

Many different instruments have been used for the measurement of hydrocarbons in exhaled air. They include the Varian Model 6000 (Varian Instrument, Sunnyvale, CA, U.S.A.) (Zarling and Clapper, 1987), Shimadzu 6-AM (Shimadzu, Seiggkuska Ltd., Kyoto, Japan) (Lemoyne et al., 1987) and Hewlett-Packard Model 5750 (Lawrence and Cohen, 1984). Gas samples are injected either directly into a sampling loop (10 ml volume) (Zarling and Clapper, 1987) or via stainless steel loops (0.2 cm i.d. x 23.4 cm) packed with adsorbents such as activated alumina (80-100 mesh) (Lemoyne et al., 1987) in order to concentrate the alkanes in the sample. 

Concomitant measurement of alkanes in exhaled air may be achieved using a 2 metre Chromosorb 102 stainless-steel column (Varian Associates) with a carrier gas flow of 30 ml/min, an injector tern-... 

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