Year : 2021 | Volume
: 11 | Issue : 1 | Page : 2--4
Use of liquid nitrogen and associated health hazards
Department of Oral Pathology and Microbiology, Dental College, Regional Institute of Medical Sciences, Imphal, Manipur, India
D B Nandini
Department of Oral Pathology and Microbiology, Dental College, Regional Institute of Medical Sciences, Imphal, Manipur
|How to cite this article:|
Nandini D B. Use of liquid nitrogen and associated health hazards.Int J Oral Health Sci 2021;11:2-4
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Nandini D B. Use of liquid nitrogen and associated health hazards. Int J Oral Health Sci [serial online] 2021 [cited 2021 Nov 30 ];11:2-4
Available from: https://www.ijohsjournal.org/text.asp?2021/11/1/2/323523
Use of liquid nitrogen and associated health hazards The use of liquid nitrogen, a commercially available cryogen in food and beverages, has become an emerging social trend at present. Liquid nitrogen is used for instant cooling of cocktail drinks, paan preparation, ice creams, and Dragon's Breath cookies to create a “cloud” or “smoke” effect and is sometimes called molecular gastronomy. It has caught the attention of everyone because of its fancy presentation. There is a lack of awareness on how these products are currently being used in foodservice premises. Liquid nitrogen is also used in industries such as aerospace, automobile, chemical manufacturing, energy, pharmaceutical, and health care. Carelessness while using liquid nitrogen causes adverse effects on the general as well as oral health.
Liquid nitrogen is an inert, colorless liquid, obtained by fractional distillation of liquid air. It has a boiling point of −196°C and remains in a liquid state only at very low temperatures. Enormous expansion of liquid nitrogen (1:694) into gaseous nitrogen can occur at room temperature, producing a fog effect as a result of moisture condensation in the air. Liquid nitrogen is usually stored in nonsealed Dewar storage containers that allow the escape of expanding gases with not more than 80% capacity, and it should never be stored in tightly sealed containers, otherwise there will be pressure buildup and explosion. Protective eye and face shields and insulated gloves should be worn while handling liquid nitrogen.
The dynamics of droplet impacts on solid surfaces have been studied for years. Hermann Boerhaave in 1732 first reported that when a liquid/water drop comes in contact with a solid/metal surface much hotter than its boiling temperature, an insulating vapor layer is formed in between them, which prevents the liquid from touching the hot solid surface and thus prevents its rapid boiling increasing the evaporation time. Thus, the water drop is long-lived. This phenomenon was named as the Leidenfrost effect and the floating drop is called Leidenfrost drop. It is named after Johann Gottlob Leidenfrost who published this in 1756. The temperature corresponding to this phenomenon is called the Leidenfrost point. This practical knowledge of droplet dynamics is used while sprinkling water on a hot cooking pan before use, performing stunts like walking on hot coal, and by magicians who escape injuries due to the Leidenfrost effect. However, careless acts result in injuries.
Liquid nitrogen causes freezing of living tissues that come in contact with it. The rapid cooling induces tissue destruction with intracellular ice formation. Freezing is quick profound and is not selective, resulting in the death of all frozen cells. Some suggested mechanisms include cellular changes related to the intracellular ice crystal formation, dehydration and consequent toxic concentration of electrolytes, thermal shock, and denaturation of lipoproteins. It also induces vascular stasis and disruption of cell membranes and local inflammatory response. Vascular stasis, clot formation may lead to thrombosis and subsequent necrosis of the frozen area. The rate of freezing also depends on the blood supply of the frozen site. These changes may be reversible on rewarming, resulting in edema. Thawing is a slower process during which the frozen area becomes hyperemic followed by swelling and hemorrhagic discoloration in few hours. On the 1st and 2nd days of freezing, necrosis and ulceration becomes evident that gradually extends to involve the entire frozen area. Healing of the soft tissue wound is observed 30 days after freezing.
Therapeutic Application in Health Care
Cryotherapy is a therapeutic method of controlled and targeted destruction of tissues by application of extreme cold. It is a simple, safe, cost-effective, less time-consuming, and bloodless procedure with minimum discomfort, minimal risk of infection, and faster healing. Cryosurgery is used to treat hyperplastic and neoplastic oral and skin lesions such as condyloma acuminate, actinic keratosis, viral wart, molluscum contagiosum, dermatofibroma, vascular malformations, hyper-melanin depigmentation techniques, leukoplakia, mucus cysts and polyps, erosive conditions, and recurrent nasopharyngeal carcinoma.
Health hazards: In February 2017, Work Safe British Columbia published a risk advisory on the use of liquid nitrogen in food preparation and classified it as an emerging risk. They have classified risks as physical and biological hazards.
This includes both consumption and handling risks that are mainly due to exposure to extreme cold. The adverse effects range from minor injuries such as cold burns; frostbite-induced oral, skin, and gastrointestinal tract ulcerations; and erosions to severe effects such as abdominal pain, peritoneum/barotrauma, gastric perforation or rupture, and shortness of breath/asphyxia.,
Frostbite of the oral cavity due to dry ice was first reported by Ohio et al. Divya and Saravanakarthikeyan reported multiple ulcers on labial mucosa following ingestion of a cookie smeared with liquid nitrogen in a 30-year-old female patient. Injuries to the lower lip, tongue, hard palate, and buccal mucosa have also been reported. The injury directly affects the mucosa or indirectly affects the structures in the vicinity of the primary site. It is lethal to be consumed internally. One should wait for the smoke to dissipate with an open mouth and then it is safe to consume. There are reports of severe injuries to the stomach, leading to stomach perforation and rupture and pneumoperitoneum/gas expansion. Some authors have reported cases with gastric perforation after ingestion of alcoholic drinks containing liquid nitrogen, necessitating gastrectomy with reconstruction.,, No food or beverage product with residual liquid nitrogen should be consumed.
There are some handling risks for the workers. Liquid nitrogen is ignitable with risk of fire, and explosion. Brief exposures to the skin may not cause harm, which is explained by the Leidenfrost effect. However, such brief exposure to liquid nitrogen can affect delicate tissues such as the eyes, leading to permanent eye damage. Incidents of frostbite on the hands, despite wearing gloves as well as death due to asphyxiation as a result of inhalation of liquid nitrogen vapors, have also been reported. Mucosal injury leading to ulceration and perforation of the airway tract can also occur. Swelling and edema of the upper airway tract or severe pharyngolaryngeal edema may necessitate immediate tracheal intubation or tracheostomy. Inadequate ventilation when using, transporting, or storage can lead to serious harmful effects and even death. A personal protection equipment kit with an eye or face shield and insulated gloves should be used to prevent injuries.,
Biological Hazard and Food Safety Risks
There may be a possible risk of contamination of the container or products during transportation and storage with subsequent preservation of fungal and bacterial spores and viruses that in turn can lead to food-borne illnesses.
With increasing popularity of cryogenic food, there are increasing reports of associated health injuries, both direct and delayed effects. Severe complications and life-threatening episodes do occur sometimes. Clinicians particularly dentists may encounter oral lesions associated with liquid nitrogen use. An awareness of the clinical presentations and appropriate history is needed to arrive at an accurate diagnosis. One has to be careful while handling liquid nitrogen, hence public awareness is also essential. Furthermore, regulatory bodies should implement appropriate measures to regulate and monitor the use of liquid nitrogen.
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