Chlorine gas poisoning

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Chlorine gas poisoning is an illness resulting from the effects of exposure to chlorine beyond the threshold limit value.

The signs of acute chlorine gas poisoning are primarily respiratory, and include difficulty breathing and cough; listening to the lungs will generally reveal crackles. There will generally be sneezing, nose irritation, burning sensations, and throat irritations. There may also be skin irritations or chemical burns and eye irritation or conjunctivitis. A person with chlorine gas poisoning may also have nausea, vomiting, or a headache.^[1][2][3]

Chronic exposure to relatively low levels of chlorine gas may cause pulmonary problems like acute wheezing attacks, chronic cough with phlegm, and asthma.^[2]

Occupational exposures constitute the highest risk of toxicity and common domestic exposures result from the mixing of chlorine bleach with acidic washing agents such as acetic, nitric or phosphoric acid. They also occur as a result of the chlorination of table water. Other exposure risks occur during industrial or transportation accidents. Wartime exposure is rare.^[2][3]

Humans can smell chlorine gas at ranges from 0.1–0.3 ppm. According to a review from 2010: "At 1–3 ppm, there is mild mucous membrane irritation that can usually be tolerated for about an hour. At 5–15 ppm, there is moderate mucous membrane irritation. At 30 ppm and beyond, there is immediate chest pain, shortness of breath, and cough. At approximately 40–60 ppm, a toxic pneumonitis and/or acute pulmonary edema can develop. Concentrations of about 400 ppm and beyond are generally fatal over 30 minutes, and at 1,000 ppm and above, fatality ensues within only a few minutes."^[2]

The concentration of the inhaled gas and duration of exposure and water contents of the tissues exposed are the key determinants of toxicity; moist tissues like the eyes, throat, and lungs are the most susceptible to damage.^[4]

Once inhaled, chlorine gas diffuses into the epithelial lining fluid (ELF) of the respiratory epithelium and may directly interact with small molecules, proteins and lipids there and damage them, or may hydrolyze to hypochlorous acid and hydrochloric acid which in turn generate chloride ions and reactive oxygen species; the dominant theory is that most damage is via the acids.^[2][3][5][6]

Tests performed to confirm chlorine gas poisoning and monitor patients for supportive care include pulse oximetry, testing serum electrolyte, blood urea nitrogen (BUN), and creatinine levels, measuring arterial blood gases, chest radiography, electrocardiogram (ECG), pulmonary function testing, and laryngoscopy or bronchoscopy.^[3]

There is no antidote for chlorine poisoning; management is supportive after evacuating people from the site of exposure and flushing exposed tissues. For lung damage caused by inhalation, oxygen and bronchodilators may be administered.^[6]

There is no way to predict outcomes. Most people with mild to moderate exposure generally recover fully in three to five days, but some develop chronic problems such as reactive airway disease. Smoking or pre-existing lung conditions like asthma appear to increase the risk of long term complications.^[1]

In 2014, the American Association of Poison Control Centers reported about 6,000 exposures to chlorine gas in the US in 2013, compared with 13,600 exposures to carbon monoxide, which was the most common poison gas exposure;^[7] the year before they reported about 5,500 cases of chlorine gas poisoning compared with around 14,300 cases of carbon monoxide poisoning.^[8]

Main article: Chlorine § Use as a weapon

• In 1915, the German Army used chlorine against Allied soldiers in the 2nd Battle of Ypres.
• In 2007 chlorine was used by insurgents in the Iraqi insurgency (2003–11),^[9]
• In 2014 chlorine was allegedly used in Kafr Zita, Syria.^[10]

There have been many instances of mass chlorine gas poisonings in industrial accidents.

• In 2002 in Missouri, a flex hose ruptured during unloading a train car at a chemical plant, releasing approximately 16,900 pounds (7,700 kg) of chlorine gas. 67 persons were injured.^[1]
• In 2004 in Macdona, Texas, a freight train accident released 9,400 US gallons (36,000 L; 7,800 imp gal) of chlorine gas and other toxic chemicals. At least 40 people were injured and three died, including two residents and the train conductor.^[11]
• In 2005 in South Carolina a freight train derailed, releasing an estimated 11,500 US gallons (44,000 L; 9,600 imp gal) of chlorine. Nine people died, and at least 529 persons sought medical care.^[12]

• In 2015, In Nigeria, the explosion of a chlorine gas storage tank at a water treatment plant in Jos killed eight people.^[13]
• In 2017, chlorine gas was released in Fort McMurray, Alberta, Canada, after chemicals were mixed improperly at a water treatment plant. In 2020 the Regional Municipality of Wood Buffalo was fined $150,000 (CAD) for the incident.^[14]
• In 2017, in Iran, at least 475 people, including nine firemen, suffered respiratory and other symptoms after a chlorine gas leak in the southwestern Iranian province of Khuzestan.^{[citation needed]}
• In 2020, on March 6, an incident occurred at EPCL (Engro Polymer and Chemicals Limited) Port Qasim, Karachi, where over 50 people were hospitalized as a result of chlorine gas leakage. No fatalities were reported.^[15]
• In 2022, on June 27, a tank holding chlorine gas in the port of Aqaba, Jordan, fell and ruptured. 14 people were killed and more than 260 were injured.^[16]

• Beach, F. X. M.; Jones, E. S.; Scarrow, G. D. (1 July 1969). "Respiratory effects of chlorine gas". Occupational and Environmental Medicine. 26 (3). BMJ: 231–236. doi:10.1136/oem.26.3.231. ISSN 1351-0711. PMC 1008943. PMID 5794948. S2CID 36220465.
• Black, J. E.; Glenny, E. T.; McNee, J. W. (31 July 1915). "Observations on 685 Cases of Poisoning by Noxious Gases Used by the Enemy". BMJ. 2 (2848): 165–167. doi:10.1136/bmj.2.2848.165. ISSN 0959-8138. PMC 2302752. PMID 20767740.
• Das, Rupali; Blanc, Paul D. (1993). "Chlorine Gas Exposure and the Lung: A Review". Toxicology and Industrial Health. 9 (3). SAGE Publications: 439–455. Bibcode:1993ToxIH...9..439D. doi:10.1177/074823379300900304. ISSN 0748-2337. PMID 8367885. S2CID 41284283.
• Chen, Jing; Mo, Yiqun; Schlueter, Connie F.; Hoyle, Gary W. (2013). "Inhibition of chlorine-induced pulmonary inflammation and edema by mometasone and budesonide". Toxicology and Applied Pharmacology. 272 (2). Elsevier BV: 408–413. Bibcode:2013ToxAP.272..408C. doi:10.1016/j.taap.2013.06.009. ISSN 0041-008X. PMC 4005342. PMID 23800689.
• Fang, Boliang; Qian, Suyun; Li, Zheng; Gao, Hengmiao; Xu, Wenmiao; Ding, Nan (10 September 2020), Case report: Acute respiratory distress syndrome and shock caused by severe chlorine gas poisoning was successfully cured by venous-arterial extracorporeal membrane oxygenation, Authorea, Inc., doi:10.22541/au.159969877.77536109, S2CID 242964247
• Govier, P.; Coulson, J.M. (2018). "Civilian exposure to chlorine gas: A systematic review". Toxicology Letters. 293. Elsevier BV: 249–252. doi:10.1016/j.toxlet.2018.01.014. ISSN 0378-4274. PMID 29355691. S2CID 38779390.
• Zellner, Tobias; Eyer, Florian (2020). "Choking agents and chlorine gas – History, pathophysiology, clinical effects and treatment". Toxicology Letters. 320. Elsevier BV: 73–79. doi:10.1016/j.toxlet.2019.12.005. ISSN 0378-4274. PMID 31811912. S2CID 208870299.

 This article incorporates public domain material from Public Health Consequences from Hazardous Substances Acutely Released During Rail Transit --- South Carolina, 2005; Selected States, 1999--2004. Centers for Disease Control and Prevention.