Mercury Exposure in a Jewelry Molding Process

Three groups of guinea pigs were exposed to 0.13, 1.01, and 5.72 ppm for 12 months. Pulmonary function measurements including tidal volume, respiratory rate, minute volume, dynamic compliance, pulmonary flow resistance, and carbon monoxide uptake indicated that no detrimental changes could be attributed to sulfur dioxide. Hematology and clinical chemistry measurements were normal, and body weight, growth, and survival were not adversely affected. Microscopic examination of the lung and trachea revealed that the group exposed to 5.72 ppm had a lower incidence and severity of spontaneous disease normally present in those animals after a period of 52 weeks. Microscopic examination of the liver revealed alterations in the animals exposed to 5.72 ppm which were characterized by an increase in the size of the hepatocytes accompanied by cytoplasmic vacuolation.     

Experimental asbestosis: an investigation of functional and pathological disturbances. I. Methods, control animals and exposure conditions.

The measurement of respiratory function and quantitative assessment of changes in lung morphology are described in a long-term study of asbestos-exposed guinea pigs. Resistance and dynamic compliance of the guinea pig respiratory system were measured non-destructively, and the tidal volume and rate of spontaneous breathing were also determined. A point counting technique was used with histological preparations to quantify morphological changes. In one group of control animals, investigated between 3 and 28 months of age, dynamic compliance and tidal volume tended to increase, but resistance and breathing rate tended to decrease, as the animals matured. In contrast the percentage by volume of various lung components remained constant throughout this period. The animals were exposed to chrysotile and amosite aerosols, both aerosols containing high concentrations of short fibres (less than 5 micrometer) and at least 1000 fibres/ml longer than 5 micrometer. The total fibre concentration during chrysotile exposure was probably at least double that during amosite exposure. A gradient of fibre concentration (less than 5 micrometer) was detected along the exposure chamber, but this gradient was not reflected in the respiratory function of animals exposed at different positions along the chamber. These findings are discussed in relation to possible dose-dependence of the response.     

“What’s in a Name”

Pulmonary parameters including tidal volume, respiratory rate, minute volume, pulmonary flow resistance, dynamic compliance of the lung, and the work of breathing were measured in unanesthetized cynomolgus monkeys. A small group of animals was tested frequently during a period of 78 weeks and regression analysis of the data, including calculations of confidence limits, provided an estimate of the variation and trends in the above parameters. A digital computer technique, which was used for real-time data analysis of the recorded analog signals, was developed to elucidate the effects of long-term exposure to low levels of pulmonary irritants and urban atmospheric pollutants, such as sulfur dioxide and nitrogen dioxide.     

Experimental asbestosis: an investigation of functional and pathological disturbances. I. Methods, control animals and exposure conditions

The measurement of respiratory function and quantitative assessment of changes in lung morphology are described in a long-term study of asbestos-exposed guinea pigs. Resistance and dynamic compliance of the guinea pig respiratory system were measured non-destructively, and the tidal volume and rate of spontaneous breathing were also determined. A point counting technique was used with histological preparations to quantify morphological changes. In one group of control animals, investigated between 3 and 28 months of age, dynamic compliance and tidal volume tended to increase, but resistance and breathing rate tended to decrease, as the animals matured. In contrast the percentage by volume of various lung components remained constant throughout this period. The animals were exposed to chrysotile and amosite aerosols, both aerosols containing high concentrations of short fibres (less than 5 micrometer) and at least 1000 fibres/ml longer than 5 micrometer. The total fibre concentration during chrysotile exposure was probably at least double that during amosite exposure. A gradient of fibre concentration (less than 5 micrometer) was detected along the exposure chamber, but this gradient was not reflected in the respiratory function of animals exposed at different positions along the chamber. These findings are discussed in relation to possible dose-dependence of the response.     

The Effect of Viscose Rayon Fibers on Lung Function in Rats

Experiments have been performed to determine the effect of viscose rayon fibers upon the pulmonary mechanics of a group of rats. Daily intratracheal injection of synthetic fiber suspension for 20 days produced an increase in index of alveolar pressure and a decrease in tidal volume, respiratory rate, and minute volume. In control animals there was no significant change in pulmonary function after intratracheal injection of normal saline. Comparison of the values after the first exposure of rayon fibers with those after intra tracheal injection of histamine did not show significant difference except in higher respiratory rate after histamine. In both exposed and control groups, infection was present when the animals were killed at the end of the experiment. The significant changes in lung function in control animals with approximately the same histological findings indicated that the changes in dust-exposed animals were mostly related to the rayon fibers.     

Tolerance to ozone in emphysematous rats

Pulmonary emphysema was induced in rats by a single intratracheal instillation of swine pancreatic elastase. After adequate development of the pulmonary emphysema, the animals were initially exposed to 1.9 ppm ozone for 3 hrs, and 3 days later, challenge-exposed to 5.1 ppm ozone for 3 hrs and immediately sacrificed to investigate the extent of the development of tolerance to ozone judged by the formation of edema. Although the body weights of the pulmonary emphysematous rats were the same as those of the saline-treated control rats, the lung weights of the former were heavier. The extent of the edema formation by ozone and of the tolerance to ozone of the pulmonary emphysematous rats seemed to be quite similar to those of the saline-treated control rats. On the other hand, although the exposure of the saline-treated control rats to 1.9 ppm ozone for 3 hrs resulted in an increase in lung weight without edema 3 days after the exposure, the pulmonary emphysematous rats did not show such a response.     

Aspects of Pulmonary Mechanics in Arc Welders'' Siderosis

Sixteen working welders with more than seven years' exposure and a chest radiograph suggestive of siderosis and 13 healthy unexposed men were studied. Each subject had a comprehensive medical and work history, physical examination, standard chest film, and pulmonary function investigation (lung volumes, ventilatory capacities, pulmonary compliance in static and dynamic conditions, specific compliance, and elastic work of breathing).

Seven of the welders had some exertional dyspnoea and three complained of cough. Although spirographic values were generally within the normal range, the arc welders had a statistically significant reduction in static and functional compliance. Seven had a functional compliance under the lower limit of the control group. Differences in elastic work of breathing and specific compliance were not significant.

The possible causes of pulmonary function impairment in welders are discussed.

     

Overall and regional lung function in dogs exposed acutely to ozone

Regional distribution of ventilation and overall function of the lungs were compared in anesthetized, paralyzed, mechanically ventilated dogs exposed to ozone. Three animals were exposed at each concentration (0,0.13,0.22, and 0.45 ppm ozone) for 3 hr. There were no significant changes in pulmonary flow resistance, dynamic compliance, or flow rates derived from maximum forced expiratory maneuvers. The distribution of inspired gas was determined using air containing 13N and a positron camera to follow wash-in in each of 80 or more regions of the lung. The mean wash-in time (T) and its standard deviation did not change in sham-treated dogs, but T increased by 40 to 100% in exposed animals. Dogs showing increases in T also had increased frequency dependence of compliance (correlation significant at P less than 0.05). The changes in 13N wash-in reflected less uniform distribution of ventilation, with the greatest disparity occurring between central and marginal regions. Altered regional mechanical function, in the absence of overall changes, suggested that the initial effect of ozone was on the small airways. The measurement may be a sensitive indicator of acute irritation in the lung periphery.     

Pulmonary Function in Spontaneously Breathing Dogs With Lower Airway Catheters

Spontaneously breathing female beagles with implanted lower airway catheters were directly exposed to puffs of whole smoke and gas phase from filter cigarettes. Measurements of peripheral and central airway resistance, tidal volume, respiratory rate, minute volume, and lung compliance were made during and after exposure to 35-ml puffs of smoke presented at one-minute intervals from five consecutively smoked cigarettes.

Peripheral resistance in four dogs during exposure to five cigarettes decreased less than 5% in response to total smoke and to gas phase. Central resistance, initially lower than peripheral resistance, increased 7% with total smoke and less than 1% with gas phase. Minute volume increased 30% with total smoke, but only about 1% with gas phase. Small, if any, change in lung compliance was noted. The addition of carbon to the filter appeared to reduce the effects of total smoke.     

Acute inhalation exposure of azodicarbonamide in the guinea pig

Humans have been exposed to azodicarbonamide (ADA) by inhalation where bulk quantities of ADA are handled in the workplace. Responses of some workers have led to concern for the potential irritant and sensitizing properties of inhaled ADA. This study examined the effects of inhaling ADA on lung structure and function of guinea pigs during and after an acute exposure. Groups of 20 guinea pigs were exposed to each of 3 concentrations of ADA (19, 58, and 97 mg/m3), plus air as a control, for 1 hr. Pulmonary function was measured before exposure (baseline), during exposure, immediately after exposure and 24 hr after exposure. Dynamic compliance (Cdyn), total pulmonary resistance (RL), tidal volume (VT), respiratory frequency and minute volume were measured. In addition, gross necropsies and histological examinations of respiratory tract tissues were done either immediately following the exposure or 24 hr after exposure. There were no effects of ADA exposure on gross necropsy, histology, Cdyn, or RL. Some significant, concentration-related decreases in VT, respiratory frequency and minute volume were seen. The magnitudes of these changes were small: the largest change was seen in minute volume, amounting to a 24% decrease in the high concentration group. Inhalation exposure of guinea pigs to ADA at concentrations of up to 97 mg/m3 resulted in minor changes in pulmonary function without any changes in lung histology.     

Toxic Metals in Hens' Eggs in India: A Preliminary Report

Lung function, biochemistry, and histology were examined in 34 silicotic and 29 control rats. Silicosis was produced by intratracheal injection of 50 mg of quartz dust. Pulmonary function tests four months after dusting showed the following changes in the silicotic rats: increases in frequency of breathing, functional residual lung capacity, lung resistance, work of breathing, oxygen consumption, and carbon dioxide tension of aortic blood; and decreased lung compliance and oxygen tension of aortic blood. Biochemical studies revealed a more than fivefold increase in wet weight of silicotic lungs and an eightfold increase in total amount of hydroxy-proline. Histologically, there were many fibrotic nodules present with emphysema in the remaining portions of the silicotic lungs. Correlation of morphological, biochemical, and functional changes and the importance of the animal-model experiments to functional examination are discussed.     

Effects of sodium nitrate aerosol on cardiopulmonary function of dogs, sheep, and man

Submicronic aerosols of nitrate salts are synthesized in the atmosphere through further oxidation of nitrogen oxides produced during the burning of fossil fuels. This study was conducted to determine whether brief exposure to submicronic aerosol of sodium nitrate in high concentrations adversely affects the cardiopulmonary system. In all studies, submicronic aerosol of sodium chloride was used as a control. Anesthetized dogs breathing up to 10 mg/m³ of sodium nitrate (NaNO₃) aerosol for 7.5 min showed no significant alterations in respiratory resistance, static lung compliance, and functional residual capacity. A 4-hr exposure to NaNO₃ aerosol (5 mg/m³) produced neither significant changes in lung mechanics, functional residual capacity, pulmonary and systemic arterial pressures, cardiac output, heart rate, and arterial blood gases in anesthetized dogs nor a change in tracheal mucous velocity in conscious sheep. Both normal and asthmatic adults who breathed submicronic aerosol of NaNO₃ (up to 1 mg/m³) for 10 min showed no significant changes in lung volumes, distribution of ventilation, ear oximetry, dynamic mechanics of breathing, and oscillation mechanics of the chest-lung system. NaNO₃ aerosol (1000 μg/m³ for 10 min did not significantly change pulmonary capillary blood flow, diffusing capacity, oxygen consumption, and pulmonary tissue volume as measured by a rebreathing technique. Thus, brief exposure to high concentrations of submicronic aerosol of sodium nitrate does not produce immediate adverse effects on cardiopulmonary function of anesthetized dogs, conscious sheep, and normal and asthmatic adults.     

腹式呼吸训练法对慢性阻塞性肺疾病伴Ⅱ型呼吸衰竭患者的效果观察

目的探讨腹式呼吸训练法对慢性阻塞性肺疾病伴Ⅱ型呼吸衰竭患者的治疗效果。方法选择我院2007年11月~2009年8月的慢性阻塞性肺疾病伴Ⅱ型呼吸衰竭患者48例,随机分为2组,分别采用不同的腹式呼吸训练法进行治疗,并与治疗前各项指标进行比较,观察治疗效果。结果经过腹式呼吸训练法1疗程治疗后,患者在肺活量、第一秒呼吸容量、氧分压、血氧饱和度等各方面指标均出现显著提高,二氧化碳分压出现显著降低。结论腹式呼吸训练法能够延长呼气时间,增加口腔压力,将压力传至末梢气道,避免气道过早关闭而降低肺泡的气陷,提高潮气量、每分钟通气量、血氧饱和度,降低呼吸频率和肺残气量。     

Periodontal Disease in Well- and Malnourished Populations

The effects on pulmonary function of inhaling the same effective dose of ozone, as well as subjective responses during continuous exercise and intermittent exercise, were studied in 12 aerobically trained men. Each subject completed 1 h of continuous exercise at work rates that elicited a mean minute ventilation of 60 l/min, and two additional 2-h intermittent exercise exposures eliciting a mean exercise minute ventilation of 45–47 l/min (i.e., total minute ventilation for each protocol was approximately 3 600 l). Subjects were exposed in randomized sequence to 0.30 ppm ozone on three occasions and to filtered air on three occasions. Forced expiratory volume in 1 s decrements of ?17.6%, ?17.0%, and ?17.9%, respectively, for the 1-h continuous exercise exposure and the two 2-h intermittent exercise exposures to 0.30 ppm ozone were significantly different. Exposure to ozone caused significant differences between postexposure subjective symptom responses; that is, responses associated with continuous exercise were greater than those for either intermittent exercise protocol. However, the overall symptom severity responses during the last minute of exercise for the two intermittent exercise protocols (at 90 and 105 min, respectively) were not significantly different from the continuous exercise postexposure value. The findings indicate that when the ozone effective dose is equivalent at a given ozone concentration, there is no difference between pulmonary function responses to continuous exercise or intermittent exercise exposures of 2-h duration (or less), although subjective symptoms are reduced somewhat during the last rest period of intermittent exercise.     

Duration of increased pulmonary function sensitivity to an initial ozone exposure

The metabolic and pulmonary function effects were investigated in six non-smoking young adults who were exposed for 2 hours (22 degrees C WBGT) to: filtered air (FA) 0.45 ppm ozone (DAY1); and two days later to a second exposure to 0.45 ppm ozone (DAY2). The subjects alternated 20-minute periods of rest and 20-minute periods of bicycle ergometer exercise at a workload predetermined to elicit a ventilatory minute volume (VE) of 27 L/min (BTPS). Functional residual capacity (FRC) was determined pre- and post-exposure. Forced vital capacity (FVC) was determined before and after exposure, as well as 5 minutes after each exercise period. Heart rate was monitored throughout the exposure, and VE, oxygen uptake (VO2), respiratory rate (fR), and tidal volume (VT) were measured during the last 2 minutes of each exercise period. There were no changes in any variable consequent to FA exposure. Both ozone exposures induced significant (P less than 0.05) decrements in FVC; FEV1.0 (forced expiratory volume in 1 second); FEV3.0 (forced expiratory volume in 3 seconds); FEF25-75% (average flow rate between 25% and 75% of FVC); and total lung capacity (TLC). The decrements following the DAY2 ozone exposure were significantly greater than following DAY1, and averaged 7.2 percentage points greater than those following the DAY1 exposure.     

A comparison of respiratory function in divers breathing with a mouthpiece or a full face mask

A comparison was made of respiratory function in submersed divers breathing with either a mouthpiece or a full face mask while exposed to varying depths (15 and 190 fsw), exercise loads (0-175 W), and static lung loads (0 and -20 cmH2O). The two types of breathing equipment were designed to be identical in terms of functional dead space volume and resistance to gas flow. When compared with data from experiments utilizing a full face mask, use of a mouthpiece caused a modest fall in expired minute volume at both depths. The majority of this decline may have been the consequence of a decrease in dead space ventilation brought about by the elimination of simultaneous nose breathing and mouth breathing. Alveolar ventilation and PETCO2 were not significantly influenced by the use of a mouthpiece, regardless of depth, workload, or static lung load. With both types of breathing gear episodes of dyspnea were infrequent during experiments with a static lung load of 0 cmH2O. Therefore, if a neutral static lung load is maintained, the type of breathing gear used does not seem to be of consequence as far as dyspnea is concerned.     

Oral and Oronasal Breathing During Continuous Exercise Produce Similar Responses to Ozone Inhalation

Breathing route has a profound effect on sulfur dioxide-induced pulmonary function response in human subjects. There is comparatively little evidence of the effects of oral, nasal, and oronasal breathing on ozone (O₃)-induced responses in humans. In this study, six young adult males were exposed on five occasions to 0.40 parts per million (ppm) O₃ while exercising continuously at one of two workloads (minute ventilation, [Vdot]_E, of ～ 30 and 75 1/min). The [Vdot]_E exposure time product was similar for all protocols. Four exposures were delivered randomly with a Hans-Rudolph respiratory valve attached to a silicone facemask, with breathing route effected with and without noseclip. A 2 × 2 analysis of variance revealed no statistically significant differences (p < .05) across conditions in pulmonary function, exercise ventilatory pattern, or subjective symptoms responses. The fifth exposure, delivered via the same respiratory valve with mouthpiece, but without facemask, revealed significantly greater forced expiratory volume in 1 s (FEV_1.0) impairment than that observed for the respiratory valve, facemask with noseclip exposure (-20.4% and -15.9%, respectively). The latter suggests partial O₃ reactivity to the facemask and clean shaven facial surface of the subjects, although reduced oral scrubbing by mouthpiece-induced bypassing of the oral vestibule might account, in part, for this difference. Recent O₃ uptake evidence from another laboratory,¹⁵ however, supports our conclusion that breathing route during moderate and heavy continuous exercise does not affect acute physiologic responses to 0.40 ppm O₃.     

Ozone and the peroxidation of polyunsaturated fatty acids in vivo

Two experiments were carried out to determine whether ozone causes significant oxidation of pulmonary polyunsaturated fatty acids in vivo. These involved ad libitum and pair-feeding. In the first experiment, rats were fed fat-free diets and exposed to ozone for 0, 1, 2, and 4 weeks. Lung and liver fatty acids were analyzed to determine if the rats exposed to ozone lost essential fatty acids more rapidly than those exposed to filtered air. In the second experiment, rats were divided into four groups. Two of these groups were fed fat-free diets, and two were fed diets containing essential fatty acids. Rats from the two diet groups (one of each type) were exposed to ozone, while the remaining two groups were exposed to filtered air. In the second experiment, rats were pair-fed. The amounts of lung and liver fatty acids were relatively uninfluenced by breathing ozone. Results from these experiments demonstrate that in the lung, the polyunsaturated fatty acids, linoleic and arachidonic acids, appear to be oxidized by filtered air and ozone at essentially the same rate.     

Effects of a single saturation dive on lung function and exercise performance

 We studied the effects of an experimental saturation dive to 360 and 450 m in a simulation chamber on spirometric lung function, diffusing capacity, pulmonary compliance, and exercise performance in eight professional divers (age 22–40 years). To assess intraindividual variability, all parameters were measured on 2 days before and on 2 consecutive days immediately after the dive. For the group as a whole there was a significant increase in vital capacity and alveolar volume, and a decrease in Krogh factor and specific compliance (P<0.01) . These changes were reduced on the 2nd day after the dive. All subjects showed lowered exercise performance after the dive. Arterial pressure of oxygen and ventilation during exercise increased (P<0.01), whereas arterial pressure of carbon dioxide, oxygen uptake, and anaerobic threshold decreased (P<0.01). Exercise parameters showed only a slight trend towards pre-dive values on the 2nd day after a dive. The individual analysis revealed that after the dive two subjects showed a marked decrease in diffusing capacity and a more than average decrease in Krogh factor (TL_CO/V_A). One of them had signs of mild decompression sickness and the other, signs of pre-existing obstructive airways disease. Our data are compatible with the hypothesis that the effects of a single deep saturation dive on pulmonary function and exercise performance are the results of counteracting mechanisms. We suggest that lung volumes increase due to the enhanced work of breathing during a deep saturation dive and that these changes could mask an impairment in gas exchange. Furthermore, a saturation dive can induce an apparent deterioration of pulmonary function. Received: 23 January 1996/Accepted: 11 March 1996     

Trends in Air Pollution Outside Los Angeles County

Polyvinyl chloride polymers and formulations were pyrolyzed in a stream of air by gradually raising the temperature from ambient to approximately 600 C. The pyrolysis air stream was diluted with twice its volume of room air, and rats were exposed to it. Exposure to an air stream containing the pyrolyzed products of 1 to 2 gm of polyvinyl chloride polymer resulted in the death of 50% of the animals. Most deaths were due to carbon monoxide (CO), and carboxyhemoglobin (COHb) levels correlated well with the amount of plastic pyrolyzed. Little histological evidence of lung damage was evident. When oxygen (O₂) was added to the air stream to prevent deaths from CO, pulmonary edema and interstitial hemorrhage developed. The lungs of some animals exposed to high levels of pyrolysis products of vinyl chloride-vinyl acetate copolymer also showed focal edema and intra-alveolar hemorrhage. Polyvinyl chloride formulations, containing additives and inert materials, were in general less toxic per gram of sample pyrolyzed.