Fatal chlorine poisoning: report of two cases with clinicopathologic correlation

Determination of biomarkers of chlorine exposure from biological samples: A review of analysis techniques

Chlorine gas can be toxic when inhaled or absorbed through the skin. Exposure to high concentrations can lead to respiratory issues, eye irritation, and skin burns. It can cause pulmonary edema, pulmonary inflammation, respiratory failure, and potentially death. Accidental releases of chlorine into the environment can harm aquatic life and ecosystems. Monitoring chlorine exposure helps in implementing proper treatment and future safeguards, such as personal protective equipment and ventilation systems. Therefore, verification of chlorine exposure is crucial to protecting human health. Many biomarkers of Cl2 exposure have been proposed, and innovative methods have been used for the analysis of those markers. In this review, sample preparation methods and analytical techniques commonly used for the determination of chlorine exposure from the analysis of biological samples proposed over the last 30 years will be discussed. The most common sample preparation methods (e.g., extraction and hydrolysis) and analysis techniques (e.g., spectrometry, spectrophotometry, and chromatography) are reviewed. In addition, the major analytical challenges of chlorine analysis are discussed. The biomarkers suggested for verification of chlorine exposure and the methods used to monitor those biomarkers in chlorine-exposed individuals are critically evaluated.

Verification of chlorine exposure via LC-MS/MS analysis of base hydrolyzed chlorophenols from chlorotyrosine-protein adducts

Inhalation of chlorine gas, with subsequent hydrolysis in the airway and lungs to form hydrochloric acid (HCl) and hypochlorous acid (HOCl), can cause pulmonary edema (i.e., fluid build-up in the lungs), pulmonary inflammation (with or without infection), respiratory failure, and death. The HOCl produced from chlorine is known to react with tyrosine to form adducts via electrophilic aromatic substitution, resulting in 3-chlorotyrosine and 3,5-dichlorotyrosine adducts. While several analysis methods are available for determining these adducts, each method has significant disadvantages. Hence, a simple and sensitive ultra-high performance liquid chromatography-tandem mass spectroscopy (UHPLC-MS/MS) method was developed for the determination of chlorotyrosine adducts. The sample preparation involves base hydrolysis of isolated plasma proteins to form 2-chlorophenol (CP) from monochlorotyrosine adducts and 2,6-dichlorophenol (2,6-DCP), from dichlorotyrosine adducts, as markers of chlorine exposure. The chlorophenols are extracted with cyclohexane prior to UHPLC-MS/MS analysis. The method produced excellent sensitivity for 2,6-DCP with a limit of detection of 2.2 μg/kg, calibration curve linearity extending from 0.054-54 mg/kg (R2 ≥ 0.9997 and %RA > 94), and accuracy and precision of 100 ± 14 %, and <15 % relative standard deviation, respectively. The sensitivity of the method for 2-CP was relatively poor, so it was used only as a secondary marker for severe chlorine exposure. The method successfully detected elevated levels of 2,6-DCP from hypochlorite-spiked plasma protein and plasma protein isolated from chlorine-exposed rats.

Persistent effects of chlorine inhalation on respiratory health

Chlorine gas is a toxic respiratory irritant that is considered a chemical threat agent because of the potential for release in industrial accidents or terrorist attacks. Chlorine inhalation damages the respiratory tract, including the airways and distal lung, and can result in acute lung injury. Some individuals exposed to chlorine experience a full recovery from acute injury, whereas others develop persistent adverse effects, such as respiratory symptoms, inflammation, and lung-function decrements. In animal models, chlorine can produce persistent inflammation, remodeling, and obstruction in large or small airways, depending on species. Airways with pseudostratified epithelia are repaired efficiently, with surviving basal epithelial cells serving as progenitor cells that repopulate the complement of differentiated cell types. Distal airways lacking basal cells are repaired less efficiently, leading to chronic inflammation and fibrosis at these sites. Persistent chlorine-induced airway disease in humans is treated with asthma medication to relieve symptoms. However, such treatment does not ameliorate the underlying disease pathogenesis, so treatments that are more effective at preventing initial development of airway disease after irritant gas exposure and at reversing established disease are needed.

Respiratory Effects of Short-Term, High-Intensity Toxic Inhalations: Smoke, Gases, and Fumes

Respiratory insufficiency resulting from inhalation of hot air, smoke, or toxic gas is a common cause of death in fire victims. Toxic gas inhalation in settings other than fires is a less common but still important cause of death and disability. Pulmonary inhalation injury and systemic intoxication from exposure to a variety of agents are discussed with regard to their pathogenesis, pathophysi ology, diagnosis, and treatment. Upper airway obstruc tion and noncardiogenic pulmonary edema are the life- threatening respiratory complications in the immediate postinhalation period. Carbon monoxide and hydrogen cyanide intoxication are frequently associated with in halation injury in fire victims. Early recognition and treatment of inhalation injury and systemic intoxication in victims of fires and industrial and environmental acci dents could well result in improved survival.

Management of chlorine gas-related injuries from the Graniteville, South Carolina, train derailment

A widely produced chemical, chlorine is used in various industries including automotive, electronics, disinfectants, metal production, and many others. Chlorine is usually produced and transported as a pressurized liquid; however, as a gas it is a significant pulmonary irritant. Thousands of people are exposed to chlorine gas every year, and while large-scale exposures are uncommon, they are not rare. Symptoms are usually related to the concentration and length of exposure, and although treatment is largely supportive, certain specific therapies have yet to be validated with randomized controlled trials. The majority of those exposed completely recover with supportive care; however, studies have shown the potential for persistent inflammation and chronic hyperreactivity. This case report describes an incident that occurred in Graniteville, South Carolina, when a train derailment exposed hundreds of people to chlorine gas. This report reviews the events of January 6, 2005, and the current treatment options for chlorine gas exposure.(Disaster Med Public Health Preparedness. 2014;0:1-6).

Mitigation of chlorine lung injury by increasing cyclic AMP levels

Chlorine is considered a chemical threat agent to which humans may be exposed as a result of accidental or intentional release. Chlorine is highly reactive, and inhalation of the gas causes cellular damage to the respiratory tract, inflammation, pulmonary edema, and airway hyperreactivity. Drugs that increase intracellular levels of the signaling molecule cyclic AMP (cAMP) may be useful for treatment of acute lung injury through effects on alveolar fluid clearance, inflammation, and airway reactivity. This article describes mechanisms by which cAMP regulates cellular processes affecting lung injury and discusses the basis for investigating drugs that increase cAMP levels as potential treatments for chlorine-induced lung injury. The effects of beta(2)-adrenergic agonists, which stimulate cAMP synthesis, and phosphodiesterase inhibitors, which inhibit cAMP degradation, on acute lung injury are reviewed, and the relative advantages of these approaches are compared.

Deviations from Haber's Law for multiple measures of acute lung injury in chlorine-exposed mice

Chlorine gas is considered a chemical threat agent that can cause acute lung injury. Studies in the early 20th century on war gases led Haber to postulate that the dose of an inhaled chemical expressed as the product of gas concentration and exposure time leads to a constant toxicological effect (Haber's Law). In the present work, mice were exposed to a constant dose of chlorine (100 ppm-h) delivered using different combinations of concentration and time (800 ppm/7.5 min, 400 ppm/15 min, 200 ppm/30 min, and 100 ppm/60 min). Significant effects of exposure protocol on survival evaluated 6 h after exposure were observed, ranging from 0% for the 7.5-min exposure to 100% for the 30- and 60-min exposures. Multiple parameters indicative of lung injury were examined to determine if any aspects of lung injury were differentially affected by the exposure protocols. Most parameters (pulmonary edema, neutrophil influx, and levels of protein, immunoglobulin M, and the chemokine KC [Cxcl1] in lavage fluid) indicated that lung injury was most pronounced for the 15-min exposure and least for the 60-min exposure. In contrast, changes in pulmonary function at baseline and in response to inhaled methacholine were similar following the three exposure regimens. The results indicate that the extent of lung injury following chlorine inhalation depends not only on total dose but also on the specifics of exposure concentration and time, and they suggest that evaluation of countermeasures against chlorine-induced lung injury should be performed using multiple types of exposure scenarios.

Long-Term Pulmonary Histopathologic Changes in Rats Following Acute Experimental Exposure to Chlorine Gas

In this study, we aimed to investigate the long-term histopathologic changes in the lungs of rats exposed to a high concentration of chlorine gas. Twenty-four Sprague-Dawley rats were divided into three groups: the control group (group I) (n = 8), early-examined group (group II) (n = 8), and late-examined group (group III) (n = 8). In group II the lungs of rats were taken out just after the exposure, whereas in group III the lungs were taken out 45 days after the exposure. Eosinophilic liquid accumulation in alveoli and bronchi, diffuse intraalveolar edema, vascular congestion, severe perivascular edema, and free bleeding in intraalveolar and interstitial area were observed in the lungs of rats in group II. Interstitial fibrosis and thickening of the alveolar septa were observed in group III. These findings suggest that the people using these cleaning agents are at risk of harming themselves, and the victims of chlorine gas injury should be reexamined at a later period since they may have pulmonary damage even after 45 days of exposure.

Acute lung injury induced by chlorine inhalation in C57BL/6 and FVB/N mice

Humans may be exposed to chlorine gas via accidental or intentional release, and effective countermeasures for the resulting lung injury are lacking. To develop a model in which therapeutic measures could be evaluated, lung injury induced by chlorine inhalation in two inbred mouse strains was examined. C57BL/6 and FVB/N mice were exposed for 1.1 h to varying doses of chlorine (197-289 ppm-h) and were evaluated for indices of lung injury at different times after exposure (6-48 h). Chlorine induced increases in lung weight that were more evident in FVB/N mice than in C57BL/6 mice. Both strains exhibited sloughing of airway epithelium observed within 6 h after exposure. As judged by Ly-6G immunostaining, chlorine exposure caused widespread neutrophil influx into the lung parenchyma at 6 h followed by a clustering of neutrophils around damaged airways by 24 h. High levels of cellular proliferation revealed by Ki-67 staining were observed in airway epithelium 48 h after exposure. Lavage fluid parameters showed consistent trends in both strains. Lavage fluid protein content was elevated throughout the times examined. Lavage fluid neutrophils were significantly increased beginning 12 h after exposure and were highest at 48 h. The concentration of the neutrophil chemoattractant KC peaked 6 h after exposure and was near baseline by 48 h. In summary, chlorine inhalation resulted in lung injury characterized by edema, epithelial cell death, and neutrophilic inflammation in C57BL/6 and FVB/N mice. Characterization of such responses in these mice will allow testing of therapeutic agents to treat chlorine-induced lung injury.

Acute respiratory distress syndrome secondary to inhalation of chlorine gas in sheep

BACKGROUND

Toxic industrial chemicals (TICs) are potential terrorist weapons. Several TICs, such as chlorine, act primarily on the respiratory tract, but knowledge of the pathophysiology and treatment of these injuries is inadequate. This study aims to characterize the acute respiratory distress syndrome (ARDS) caused by chlorine gas (Cl2) inhalation in a large-animal model.

METHODS

Anesthetized female sheep were ventilated with 300 L of a Cl2/air/oxygen mixture for 30 minutes. In phase 1 (n = 35), doses were 0 ppm (Group 1, n = 6); 120 ppm (Group 2, n = 6); 240 to 350 ppm (Group 3, n = 11); and 400 to 500 ppm (Group 4, n = 12). In phase 2 (n = 17), doses were 0 ppm (Group 5, n = 5); 60 ppm (Group 6, n = 5); and 90 ppm (Group 7, n = 7), and the multiple inert gas elimination technique (MIGET) was used to characterize the etiology of hypoxemia. Computed tomography (CT) scans were performed daily for all animals.

RESULTS

In Phase 1, lung function was well maintained in Group 1; Cl2 caused immediate and sustained acute lung injury (PaO2-to-FiO2 ratio, PFR<3.0) in Group 2 and ARDS (PFR<2.0) in Groups 3 and 4. All animals in Groups 1 and 2 survived 96 hours. Kaplan-Meier analysis showed dose-related differences in survival (log-rank test, p < 0.0001). Logistic regression identified 280 ppm as the lethal dose 50%. CT and histopathology demonstrated lesions of both small airways and alveoli. In Phase 2, MIGET showed diversion of blood flow from normal to true-shunt lung compartments and, transiently, to poorly ventilated compartments.

CONCLUSIONS

Cl2 causes severe, dose-related lung injury, with features seen in both smoke inhalation and in ARDS secondary to systemic disease. This model will be used to test new therapeutic modalities.

Clinical management of casualties exposed to lung damaging agents: a critical review

There is no specific antidote for the treatment of casualties exposed to chlorine, phosgene, or mustards; therefore, management is largely supportive. Corticosteroid treatment has been given to casualties accidentally exposed to chlorine. Clinical data on efficacy are inconclusive as the numbers given steroids have been small and the indications for administration unclear. There have been no clinical controlled studies. There is a stronger evidence base from animal studies, particularly from porcine and rodent models. Lung injury induced by phosgene and mustard appears to be mediated by glutathione depletion, lipid peroxidation, free radical generation, and subsequent cellular toxicity. There is limited evidence to suggest that repletion of glutathione reduces and/or prevents lung damage by these agents. This may provide an opportunity for therapeutic intervention.

Effects of chlorine and its cresylate byproducts on brain and lung performance

Chlorine and potassium cresylate spilled from a train wreck forced evacuation of nearly 1000 people in and near the town of Alberton, Montana, in 1996. Because respiratory and other symptoms persisted in this population, neurobehavioral and pulmonary functions were evaluated in a cohort of exposed vs. unexposed individuals. Ninety-seven subjects were tested 7 wk after exposure. Three years later, 36 of the original subjects were retested, along with 21 new patients exposed in the same incident. These 57 were compared with 22 unexposed individuals. Twenty-six neurobehavioral functions were tested, and spirometry was performed on each subject. At 7 wk postexposure, patients showed significant differences in 5 neurobehavioral functions (i.e., balance, simple reaction time, abnormal visual quadrants, vocabulary, and information), compared with the unexposed individuals recruited in 1999. Patients' Profile of Mood States scores and frequencies of 35 symptoms were also elevated, compared with the unexposed group. At 3 yr postexposure, patients exhibited differences in 7 additional neurobehavioral functions (i.e., choice reaction time, balance with eyes open, color errors, visual fields, Culture Fair, and verbal recall). Respiratory symptoms were increased, but pulmonary functions did not change. Exposure to chlorine and potassium cresylate produced neurobehavioral impairments that have been observed to increase across 3 yr. Spills in heavily populated areas could injure thousands, overwhelming medical facilities.

Inhaled and intravenous corticosteroids both attenuate chlorine gas-induced lung injury in pigs

BACKGROUND

The accidental release of chlorine gas is a constant threat in urban areas. The purpose of this randomized, blinded, controlled experiment was to examine the effects of post-injury administration of inhaled or intravenous corticosteroid in chlorine gas-injured pigs followed for 23 h.

METHODS

Anaesthetized, ventilated pigs (n = 24) in the prone position were exposed to chlorine gas (400 parts per million in air) (1160 mg/m3) for 15 min, then randomly allocated to receive inhaled budesonide (BUD) and intravenous placebo, intravenous betamethasone (BETA) and inhaled placebo or inhaled and intravenous placebo. Haemodynamics, gas exchange and lung mechanics were evaluated for 23 h after exposure to chlorine gas.

RESULTS

Airway and pulmonary artery pressures increased and arterial oxygenation fell sharply (from 13.5 +/- 0.8 to 6.7 +/- 0.9 kPa, P < 0.001) after chlorine gas exposure. These immediate changes were followed by a gradual improvement over 5-7 h to a stable level of dysfunction for the rest of the experiment in placebo animals. Arterial oxygen tension, pulmonary vascular resistance and airway pressure recovered faster and more completely in the budesonide and betamethasone groups than in the placebo group (P < 0.01). Lung wet weight to dry weight ratios were greater in the placebo group than in the budesonide and betamethasone groups (6.34 +/- 0.59 vs. 5.56 +/- 0.38 and 5.53 +/- 0.54, respectively, P < 0.05). There was a trend towards lower histological injury scores compared with placebo in animals that received budesonide (P = 0.05) or betamethasone (P = 0.07).

CONCLUSION

Treatment of chlorine gas lung injury with nebulized budesonide or intravenous betamethasone had similar positive effects on recovery of lung function.

Administration of Aerosolized Terbutaline and Budesonide Reduces Chlorine Gas–Induced Acute Lung Injury

BACKGROUND

The pathophysiology and treatment of chlorine gas-induced acute lung injury is poorly characterized and based on anecdotal data. This study aimed to assess the effects of aerosolized beta-2 adrenergic agonist and corticosteroid therapy on chlorine gas-induced lung injury.

METHODS

Anesthetized, ventilated pigs were exposed to chlorine gas (400 parts per million for 20 minutes), then assigned randomly 30 minutes later to receive aerosolized terbutaline, budesonide, terbutaline followed by budesonide or placebo (6 pigs in each group). Hemodynamics, gas exchange, and lung mechanics were evaluated for another 5 hours.

RESULTS

All the animals demonstrated an immediate increase in airway and pulmonary artery pressure as well as sharp drops in arterial oxygen tension (PaO2) and lung compliance (CL). Recovery of PaO2 and CL was greatest in the terbutaline plus budesonide group, but therapy with terbutaline and budesonide alone also was associated with significant improvement in PaO2 and CL, as compared with placebo.

CONCLUSIONS

Treatment of acute chlorine gas lung injury with aerosolized terbutaline followed by aerosolized budesonide improved lung function. Combined treatment was more effective than treatment with either drug alone.

Chlorine-induced injury to the airways in mice

Exposure to chlorine gas (Cl2) causes occupational asthma that we hypothesized occurs through the induction of airway inflammation and airway hyperresponsiveness by oxidative damage. Respiratory mechanics and airway responsiveness to methacholine were assessed in A/J mice 24 hours after a 5-minute exposure to 100, 200, 400, or 800 ppm Cl2 and 2 and 7 days after inhalation of 400 ppm Cl2. Airway responsiveness was higher 24 hours after 400 and 800 ppm Cl2. Responsiveness after inhalation of 400 ppm Cl2 returned to normal by 2 days but was again elevated at 7 days. Airway epithelial loss, patchy alveolar damage, proteinaceous exudates, and inflammatory cells within alveolar walls were observed in animals exposed to 800 ppm Cl2. Macrophages, granulocytes, epithelial cells, and nitrate/nitrite levels increased in lung lavage fluid. Increased inducible nitric oxide synthase expression and oxidation of lung proteins were observed. Epithelial cells and alveolar macrophages from mice exposed to 800 ppm Cl2 stained for 3-nitrotyrosine residues. Inhibition of inducible nitric oxide synthase with 1400W (1 mg/kg) abrogated the Cl2-induced changes in responsiveness. We conclude that chlorine exposure causes functional and pathological changes in the airways associated with oxidative stress. Inducible nitric oxide synthase is involved in the induction of changes in responsiveness to methacholine.

Effects of prone and supine posture on cardiopulmonary function after experimental chlorine gas lung injury

BACKGROUND

Chlorine gas may induce severe acute lung injury. Improvement of pulmonary gas exchange in patients and animals with acute lung injury nursed in the prone position was observed in recent years. The purpose of this study was to evaluate the effects of prone and supine positions on pulmonary and cardiovascular functions following experimental chlorine gas lung injury.

METHODS

Twenty anesthetized and mechanically ventilated pigs were exposed to chlorine gas (400 p.p.m. in air) for 20 min in the supine position, then assigned randomly to ventilation in the supine or prone positions (n=10 in each group). Hemodynamics, gas exchange, lung mechanics and oxygen transport were evaluated for 5 h.

RESULTS

All animals showed severe pulmonary dysfunction immediately after chlorine gassing with a threefold increase in pulmonary vascular resistance index, a drop in arterial oxygenation (12.3+/-1.3 kPa to 5.4+/-0.7 kPa) and a fall in lung-thorax compliance (22+/-1 ml cmH2O-1 to 8+/-2 ml cmH2O-1). Venous admixture (Qs/Qt) improved in animals in the prone position while there was no change in the supine position (prone 32+/-11% vs. supine 42+/-9% at 5 h,P<0.05). Lung-thorax compliance improved significantly with time in the prone group only (P<0.01). Oxygen delivery increased significantly in prone animals compared with animals nursed in the supine posture (P<0.001).

CONCLUSION

Immediate prone positioning after chlorine gas injury not only inhibited deterioration of gas exchange but was also associated with improved pulmonary function and oxygen transport.

Fatal pulmonary arterial thrombosis associated with chlorine gas poisoning

We present a patient with accidental chlorine gas poisoning who died from pulmonary thrombosis due to a marked increase in hemostatic factors such as von Willebrand factor after recovering from the acute poisoning.

Are high-dose toxic exposures always associated with reactive airways dysfunction syndrome (RADS)?

Bottling plant workers were evaluated for respiratory symptoms following an accidental exposure to a chlorine dioxide aerosol. Six exposed employees underwent medical and occupational histories, skin testing to common allergens, spirometry before and after use of bronchodilators, and methacholine challenge. The reported exposure to chlorine dioxide ranged from 30 min to 12 hr. Physical examinations were all normal. Four workers had positive prick skin tests to common aeroallergens. None of the workers demonstrated significant changes in forced expiratory volume in 1 sec following use of bronchodilators, and none experienced methacholine hyperresponsiveness. These cases suggest that the occurrence of reactive airways dysfunction syndrome is unpredictable and may not always occur in heavily exposed individuals.

Short term respiratory effects of acute exposure to chlorine due to a swimming pool accident

OBJECTIVE

Acute exposure to chlorine causes lung damage, and recovery may proceed slowly for several weeks. The short term respiratory effects of acute chlorine inhalation during a swimming pool accident were examined.

METHODS

A total of 282 subjects (134 children, aged <14 years) inhaled hydrogen chloride and sodium hypochlorite during an accident caused by a malfunction of the water chlorinating system in a community pool in Rome in 1998. Most people received bronchodilators and cortisone at the emergency room; five children were admitted to hospital. A total of 260 subjects (92.2%) were interviewed about duration of exposure (<3, 3--5, >5 minutes), intensity of exposure (not at all or a little, a moderate amount, a lot), and respiratory symptoms. Lung function was measured in 184 people (82 children) after 15--30 days. The effects of exposure to chlorine were analysed through multiple linear regression, separately in adults and in children.

RESULTS

Acute respiratory symptoms occurred among 66.7% of adults and 71.6% of children. The incidences were highest among those who had chronic respiratory disease and had a longer duration of exposure. In about 30% of the subjects, respiratory symptoms persisted for 15--30 days after the accident. Lung function levels were lower in those who reported a high intensity of exposure than in those who reported low exposure, both in children and in adults (mean (95% confidence interval (95% CI)) differences in forced expiratory volume in 1 second (FEV(1,)) were -109 (-310 to 93) ml, and -275 (-510 to -40) ml, respectively).

CONCLUSION

Persistent symptoms and lung function impairment were found up to 1 month after the incident. Although community pool accidents happen rarely, the medical community needs to be alerted to the possible clinical and physiological sequelae, especially among susceptible people.

The toxicology of chlorine

Chlorine is a reactive gas used by humanity for over two centuries. Exposure to chlorine has occurred in a number of situations, including as a chemical warfare agent, in industrial and domestic exposures, and as a result of accidents and spills. The toxicology of chlorine is related almost entirely to effects in the respiratory system. A consistent symptomology occurs in both animals and humans. This ranges from sensory irritation, to irritation and bronchospasm, to cellular changes to bronchioles and alveoli, to development of pulmonary disease. While full recovery from such injuries remains the most likely outcome, there is little doubt that permanent loss of function is possible in severe cases. In all industrial applications of chlorine, occupational exposures to chlorine should be controlled to at least the recommended exposure standard. However, a focus of activity on ensuring that excursions (such as leaks or "gassing" incidents) above these values do not occur is likely to be more beneficial. Treatment of chlorine exposure is essentially symptomatic, with the efficacy of some treatments (such as corticosteroid therapy) still not well established.

Chlorine inhalation: the big picture

BACKGROUND

Causes of acute chlorine exposures from community pool accidents have many reported etiologies. This case series involves 13 children exposed to high levels of chlorine at two community pools after an unusual mishap in the chlorination maintenance procedure.

CASE REPORT

During maintenance, the water feeding lines to pools are normally turned off, the chemicals replaced, the water turned back on, and the chemicals then reinjected into the line. In two separate disasters in the summer of 1996, the feeding lines were not reprimed with water before the reactants, sodium hypochlorite and muriatic acid, were injected. This caused an unusually high volume of concentrated chlorinated water to be released when refed to the pool.

RESULTS

All patients were treated with beta agonists and humidified oxygen, and five were admitted. None received bicarbonate inhalation. An extensive literature review of chlorine inhalation injuries indicates considerable variance in opinions of the pathophysiology, clinical presentation and treatment modalities, especially steroids and bicarbonate inhalation.

CONCLUSION

In community pools, failure to reprime feeding lines with water after replacing and injecting chlorinating reactants may result in severe and large-scale chlorine exposures. Beta agonist administration and humidified oxygen remains the mainstay of treatment; steroid therapy and bicarbonate inhalation are still inadequately supported.

Inhalation of chlorine gas

The clinical features of acute chlorine gas inhalation, and its management are reviewed. Current medical views on the chronic effects of an acute overwhelming exposure on lung function (reactive airways dysfunction syndrome), and the more controversial field of lung disease secondary to repeated inhalations of lower concentrations of chlorine gas are discussed.

Explosion risk from swimming pool chlorinators and review of chlorine toxicity

Two patients were admitted to the hospital emergency room in respiratory distress after an accidental explosion involving chlorinating agents for the swimming pool. The two primary agents involved were calcium hypochlorite and trichloro-s-triazinetrione; both are commonly used chlorinating agents. These chemicals were tested in a bomb apparatus measuring temperature and gas production. Combining the two chlorinators at 2, 6, 12, or 18 g of each produced a progressive increase in gas production from 234 to 1422 mL. The temperature increased from 30 degrees C at 2 g to 63 degrees C at 18 g. The time to complete the reaction decreased from 6.2 minutes at 2 g to 3.8 minutes at 18 g. The third run at the 18 g level resulted in an explosion. The results indicate that gas generation is dependent on both products. The addition of organic material was abandoned because of the explosive nature of the reaction. The amount of calcium hypochlorite primarily determines the rate of reaction and heat generation. Appropriate emergency action and treatment for chlorine gas is discussed.

Chlorine gas exposure and the lung: a review

We conducted a review of the literature detailing the respiratory effects of chlorine, an extremely important but toxic halogen. Historically, the heaviest mass inhalational exposures to chlorine resulted from World War I gassing. Currently potential human exposure to chlorine inhalation occurs in a variety of settings in the workplace, as a result of inadvertent environmental releases, and even in the home due to household cleaning mishaps. Chlorine species are highly reactive; tissue injury results from exposure to chlorine, hydrochloric acid, hypochlorous acid, or chloramines. Acute, high level exposure to chlorine gas in occupational or environmental settings results in a variety of dose-related lung effects ranging from respiratory mucus membrane irritation to pulmonary edema. Pulmonary function testing can reveal either obstructive or restrictive deficits immediately following exposure, with resolution over time in the majority of cases. However, some of those exposed may demonstrate long-term persistent obstructive or restrictive pulmonary deficits or increased nonspecific airway reactivity after high level exposure to chlorine gas. Symptoms and signs following inhalation of mixtures of chlorine-containing cleaners in the home are similar to those after occupational exposures and environmental releases. Although generally less severe, these events may be extremely common. Controlled human exposure data suggest that some subjects may be more responsive to the effects of chlorine gas; epidemiologic data also indicate that certain subpopulations (e.g., smokers) may be at greater risk of adverse outcome after chlorine inhalation. Although these findings are intriguing, additional study is needed to better delineate the risk factors that predispose toward the development of long-term pulmonary sequelae following chlorine gas exposure.

A case-control study of lung cancer at a dye and resin manufacturing plant

This case-control study evaluated the relationship between lung cancer and occupational factors among employees at a dye and resin manufacturing plant. The study included 51 lung cancer cases and 102 controls who were members of a cohort of workers investigated in a previous retrospective follow-up study. Information on area of employment and on potential exposure to certain chemicals was obtained from plant personnel and medical records and from interviews with long-term employees. Information on potential confounders, including cigarette smoking, was obtained by interviewing study subjects or their next-of-kin. The odds ratio (OR) for heavy smokers compared with light or nonsmokers was 5.9 (95% confidence interval (CI) = 2.4-15). An elevated OR for lung cancer was observed for subjects who worked in the anthraquinone dye and epichlorohydrin manufacturing area of the plant (OR = 2.4; 95% CI = 1.1-5.2) and for employees who were seen at the plant infirmary for acute exposure to chlorine (OR, adjusted for smoking = 27; 95% CI = 3.5-205). Pipefitters employed at the plant for five or more years also had an elevated OR (3.3; 95% CI = 0.8-14).

Treatment of acute chlorine gas inhalation with nebulized sodium bicarbonate

Three male patients, 19 to 20 years old, were exposed to chlorine gas secondary to a leak in the chlorination system of an indoor pool. All of the patients were symptomatic with cough, chest pain, and shortness of breath. Physical examinations, arterial blood gases, and chest radiographs were normal. All patients were given a nebulized solution of 3.75% sodium bicarbonate which resulted in prompt relief of their symptoms. None of the patients suffered from prolonged symptomatology. This therapy appears to be useful in treating chlorine gas inhalation; however, it cannot be routinely recommended without prospective clinical studies evaluating its efficacy and safety.

The pulmonary sequelae associated with accidental inhalation of chlorine gas

Twenty previously healthy individuals were accidentally exposed to high concentrations of chlorine gas in 1975. Pulmonary function tests were performed on these individuals on several occasions over the next 12 years. On average, each subject was followed up for 8.5 years and 13 of the 20 exposed persons were tested 12 years following the exposure. Pulmonary function tests obtained one day following the accident were most notable for the high prevalence of airflow obstruction and air trapping. Over the ensuing years, the airflow obstruction persisted; however, the high prevalence of air trapping resolved. Of note, the prevalence of a low residual volume consistently increased during the follow-up period (p less than 0.001) and at year 12, 67 percent of those tested had residual volumes below 80 percent of their predicted value. We also found that five of 13 subjects tested at year 12 had an increase in airway reactivity (greater than 15 percent decline in FEV1) to inhaled methacholine. Those individuals with reactive airways were older (p = 0.004) and had more marked airflow obstruction (p = 0.03) and air trapping (p = 0.03) immediately following the exposure. These data suggest that exposure to high concentrations of chlorine gas may result in long-term pulmonary complications that are characterized by a reduced residual volume. Unfortunately, these data preclude us from determining whether the chlorine exposure led to the development of airway reactivity or the presence of reactive airways accounted for the air trapping that was observed following the exposure to chlorine gas.

Respiratory cytopathology in chlorine gas toxicity: a study in 28 subjects

Bronchial brushings to evaluate cytopathologic changes were collected from 28 patients exposed to a toxic atmospheric level (66 parts/million) of chlorine gas. Postexposure smears collected on day 5 showed basal-cell and goblet-cell hyperplasia, acute inflammation, and chromatolysis of columnar epithelial cells. Columnar epithelial cell syncytia were observed in 15 (53.57%) smears. Nine (32.14%) smears showed abundant nonpigmented alveolar macrophages. Seven (25%) smears from mucosal erosions showed proliferating fibroblasts and capillary fragments; on day 15 and day 25 repeat smears from these seven cases showed evidence of epithelial regeneration and repair by fibrosis. This latter feature could lead to chronic ventilatory incapacitation in patients exposed to toxic levels of chlorine gas.

Hyperchloremic metabolic acidosis after chlorine inhalation

Chlorine gas inhalation is usually accompanied by pulmonary toxicity and hypoxemia; the associated acidemia, when present, has been attributed to lactic acidosis. This case report describes the development of hyperchloremic metabolic acidosis following accidental chlorine gas exposure. The mechanism postulated for the production of this acidosis is the absorption of hydrochloric acid following the reaction of chlorine gas with tissue water. This may be the first case of chlorine toxicity in which the mechanism of the acidosis has been determined.

Pathology of toxic responses to the RD50 concentration of chlorine gas in the nasal passages of rats and mice

Male Swiss-Webster mice and Fischer-344 rats were exposed to chlorine gas at their respective RD50 concentrations (ca. 9 to 11 ppm). The RD50 concentration is that concentration which reduces respiratory rate by 50%. The exposures were carried out for 6 hr per day for 1, 3, or 5 days, and the animals were killed immediately at the end of the last exposure. The nasal passages were examined by light and scanning electron microscopy. Lesions were observed in all exposed groups and were of similar severity and character in rats and mice. The most severe changes were found in the olfactory mucosa of the anterior portion of the dorsal meatus and consisted of partial to complete degeneration of olfactory sensory cells, with olfactory sustentacular cells being more resistant to chlorine exposure. Lesions in the respiratory epithelium were located primarily on the free margins of the naso- and maxilloturbinates and adjacent nasal septum. Scanning electron microscopy, using large size specimens, demonstrated loss of olfactory cilia in areas of the olfactory epithelium which appeared unaffected by light microscopy. Scanning electron microscopy was also helpful in locating areas of respiratory epithelium exhibiting loss of cilia and cellular exfoliation, which occurred primarily on naso- and maxilloturbinates. Therefore, chlorine-induced severe lesions in specific locations in both the olfactory and respiratory epithelia of the nasal passages with more widespread loss of respiratory and olfactory cilia.

Resolution of pulmonary dysfunction following acute chlorine exposure

Following acute exposure to chlorine gas, 18 asymptomatic subjects were evaluated for early pulmonary dysfunction. Airway obstruction was evident in all exposed individuals immediately after chlorine exposure. The severity, course of the obstructive defect, and clinical picture correlated with the chief complaint on admission. The obstructive abnormalities resolved within 1 wk after exposure to chlorine in 12 subjects whose chief complaint was cough. A slower resolution of the physiologic changes, clinical signs, and symptoms was noted in 6 subjects whose initial chief complaint was dyspnea. In this group, maximum mid-expiratory flow rate (FEF25-75%), and forced expiratory flow after exhaling 50% and 75% of the vital capacity (FEF50% and FEF25%, respectively) were still diminished 2 wk after chlorine exposure. The slow rate of resolution in the dyspnea group is best explained by increased individual susceptibility since a past medical history of smoking or asthma and "wheezing" was more prevalent in this group.

Electrolytic destruction of lung tissue in the rabbit

Tissue destruction was produced by electrolysis after insertion of electrodes into the rabbit lung. The anode was the active electrode and the best electrode material was platinum. The lesions formed around the electrode were well demarcated and their size varied in relation to the charge applied. Complications were few and the lesions healed quickly. Tissue injury occurs as the result of chlorine liberation at the anode, the basis for which is chloride ion oxidation.

Acute chlorine gas exposure

The heavy use of chlorine gas in industry and water purification poses the constant threat of mass gas exposure. In a recent experience with a chlorine gas disaster involving over 100 patients, 64, including six subsequently requiring admission, were treated in the main emergency unit facility. The remainder were triaged to a safe area away from the emergency unit with instructions for symptomatic treatment. Injuries were limited to four organ systems: pulmonary, gastrointestinal, ophthalmic, and cutaneous. Current treatment methods are compared with those in the literature and a protocol for management provided.

Poisoning caused by inhalation of hydrogen chloride, phosphorus oxychloride, phosphorus pentachloride, oxalyl chloride, and oxalic acid

Eleven people accidentally inhaled a significant amount of a gaseous mixture of hydrogen chloride, phosphorus oxychloride, phosphorus pentachloride, oxalyl chloride, and oxalic acid. Clinical observations and laboratory tests were recorded from the time of admission throughout hospitalization. The main abnormalities were found in the respiratory tract and consisted of clinical and physiologic evidence of obstruction of the airways, mild interstitial and alveolar edema, a defect in diffusion, and inequalities of ventilation and perfusion that produced hypoxemia. All of these cleared within a short time.

Pulmonary injury following exposure to chlorine gas. Possible beneficial effects of steroid treatment

Two sisters were exposed to chlorine gas in toxic quantities in the same room of their home during an industrial accident. One was hospitalized and treated with corticosteroids and oxygen therapy, while the other received evaluation in the emergency room, and brief oxygen therapy and was released without corticosteroid therapy. Pulmonary physiologic studies have been performed on both patients at intervals following the exposure. The treated patient was stable, with normal results on studies of pulmonary function at the end of two years, while the sibling not treated with corticosteroids had demonstrable abnormalities of gas exchange which persisted during 55 months of observation. This "natural experiment" gives evidence of prolonged detrimental effects of sublethal exposure to chlorine gas on human pulmonary function in some patients. The effect of the differences in treatment between the two siblings cannot be definitely assessed in this single situation.

Comparison of the sensory irritation response in mice to chlorine and hydrogen chloride

Groups of male Swiss-Webster mice were exposed to concentrations of chlorine varying from 0.7 to 38.4 ppm and to concentrations of hydrogen chloride varying from 40 to 943 ppm. The total exposure time to both gases was 10 minutes. Dose-response curves were plotted for both chlorine and hydrogen chloride, using the percentage decrease in respiratory rate during each exposure as the response reflecting sensory irritation of the upper respiratory tract. The results showed chlorine to be 33.0 times more irritating than hydrogen chloride, with 95% confidence limits of 18.6 and 57.1. Guidelines for obtaining a range of acceptable threshold limit values (TLV) based on sensory irritation of the upper respiratory tract are discussed. It was concluded that the current TLV of 1 ppm for chlorine is the upper acceptable limit, and that the established TLV of 5 ppm for hydrogen chloride lies at the lower limit of the predicted range. The mechanism of chlorine's and hydrogen chloride's sensory irritation may be explained by their reaction with various functional groups in the membranes of the trigeminal nerve endings lining the nasal mucosa.