Environmental pathology

Last updated: February 4, 2022

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Environmental pathology is the study of conditions that are caused by exposure to environmental factors such as extreme temperature and altitude changes, electricity, wildlife, and any kind of toxin.

Electrical injuries are often multisystem injuries and require a thorough evaluation. Burns of varying degrees are among the most common findings. Exposure to alternating current can lead to potentially life-threatening arrhythmias. Lightning injuries, a rare subtype of electrical injuries, may manifest with characteristic skin findings, such as Lichtenberg figures.

High-altitude illness, which typically occurs at elevations > 8,000 ft (∼ 2,500 m), encompasses acute mountain sickness, high-altitude cerebral edema, and high-altitude pulmonary edema. The main trigger is the low level of oxygen, which can lead to hypoxia, tachypnea, polycythemia, pulmonary edema, and cerebral edema during the first hours to days at high altitude.

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Electrical current (industrial or residential) injury [1]

  • Epidemiology
    • Electrical injuries account for approx. 4% of admissions to specialized burn services. [2]
    • Setting
      • Children: most often household injury
      • Adults: most often in occupational settings
    • Workplace-related electrical injuries cause approx. 150 deaths per year in the US. [3]
  • Etiology
    • High-voltage sources (> 1000 V): e.g., lightning strike, industrial devices, power supply lines
    • Low-voltage sources (120–1000 V): e.g., household appliances, extension cords, or wall outlets
  • Pathophysiology: Electrical current enters the body (entry point), passes through tissues and organs, and then exits the body (exit point).
    • The majority of tissue damage is a result of thermal injury, which occurs as the electric current converts to heat when entering the tissue.
    • Nonthermal injury includes direct electric injury to nerve tissue and musculoskeletal injury (secondary to tetanic muscle contraction).
    • The severity of the injury depends on:
      • Current
        • Direct current (DC): e.g., in batteries, cars, computers
        • Alternating current (AC): most household electronic devices (e.g., TV, toaster, washing machine) and wall outlets
        • AC is generally more dangerous than DC, because AC is more likely to trigger ventricular fibrillation.
      • Frequency (in Hz): Low-frequency AC (< 300 Hz) causes muscle contraction, which may prevent the individual from letting go of the source, prolonging exposure.
      • Voltage (V): The higher the voltage of a source, the more severe the injury it may cause.
      • Resistance of tissue
        • Dry skin has a higher resistance than wet skin.
        • The lowest resistance is in water.
  • Clinical features: Electrical injury often affects multiple systems.
  • Management: In general, individuals with (suspected) electrical injury should be treated as trauma patients (see “Management of trauma patients”). A thorough evaluation and frequent reassessments are necessary, as some injuries may not be visible at first.
  • Prevention
    • Following workplace safety rules
    • Education about potential sources of household and workplace exposure
    • Outlet guards
    • Proper incorporation of protective circuit-breaking equipment

Lightning injury [1][4]

Acute mountain sickness (AMS) [6]

Acclimatization to high altitude
Parameter Early changes Late changes
PAO2 and PaO2
PACO2 and PaCO2
Arterial pH
  • Normal (due to renal compensation)
  • Normal
Arterial O2 content
  • Returned to normal

High-altitude cerebral edema (HACE)

High-altitude pulmonary edema (HAPE) [7]

Decompression sickness

  • Definition: : the formation of air bubbles in the tissue and venous circulation caused by a rapid decline in barometric pressure within the body
  • Etiology
  • Pathophysiology: decompression sickness due to diving
    • Descent: ambient pressure increases with diving depth → gases (mostly nitrogen) dissolve into the blood and tissue
    • Controlled ascent: ambient pressure gradually decreases → gas tension exceeds the surrounding pressure → gases slowly come out of solution → gases exhaled
    • Rapid ascent: ambient pressure rapidly decreases → gas tension exceeds the surrounding pressure → gases quickly come out of solution in the blood and tissue → insufficient time for the gas to be progressively breathed out through the lungs → formation of gas bubbles → gaseous obstruction of blood flow (especially in the venous circulation because of its lower pressure and higher gas tension)
  • Clinical features
  • Management
  • Complications
  • Prevention
    • Avoid situations involving a rapid decline in barometric pressure.
    • Follow diving safety guidelines (e.g., pay attention to diving limits, make safety stops during the ascent).


Nitrogen narcosis [12]

  • Definition: a syndrome caused by increased nitrogen levels from breathing compressed air while diving at depth
  • Onset: diving at depths ≥ 100 ft
  • Risk factors: use of alcohol, sedatives, analgesics before diving
  • Pathophysiology: ↑ ambient pressure under water → ↑ partial pressure of nitrogen → ↑ solubility in neuronal membranes → ↓ excitability → intoxication and narcosis
  • Clinical features: severity of symptoms increases with diving depth; symptoms disappear rapidly after ascending to shallower depths
  • Diagnostics: clinical diagnosis
  • Treatment: immediate ascent
  • Prevention: switching from nitrogen-based mixtures to helium-based mixtures or staying above 100 ft

Ear barotrauma (barotitis media, aerotitis media)

Green tobacco sickness [14]

  • Definition: a form of nicotine poisoning that predominantly affects tobacco harvesters
  • Risk factors
    • Children and adolescents with environmental exposure to tobacco are at increased risk because of higher sensitivity to nicotine.
    • Wet conditions (e.g., due to rain, dew, sweat) promote nicotine absorption
  • Etiology: nicotine exposure
  • Pathophysiology: transdermal absorption of nicotine from tobacco plants
  • Clinical features
  • Treatment: usually not required
  • Complications: vomiting → dehydration↑ risk of heat illness
  • Prognosis: usually resolves without treatment within 24 hours
  • Prevention
    • Wearing personal protective equipment (PPE) such as long pants, long-sleeve shirts, water-resistant clothing, and gloves
    • Educating workers on the symptoms of green tobacco poisoning and the necessity of PPE
    • Washing with soap and water immediately after skin contact

Anhydrous ammonia poisoning [15]

In case of ingestion: do not induce emesis to prevent re-exposure of the esophagus and mouth!

  1. Luks AM et al.. Acute high-altitude sickness. European Respiratory Review. 2017; 26 (143): p.160096. doi: 10.1183/16000617.0096-2016 . | Open in Read by QxMD
  2. Stream JO, Grissom CK. Update on High-Altitude Pulmonary Edema: Pathogenesis, Prevention, and Treatment. Wilderness and Environmental Medicine. 2008; 19 (4): p.293. doi: 10.1580/07-weme-rev-173.1 . | Open in Read by QxMD
  3. ONeill OJ, Brett K, Frank AJ. Middle Ear Barotrauma. StatPearls. 2021 .
  4. Rozycki SW, Brown MJ, Camacho M. Inner ear barotrauma in divers: an evidence-based tool for evaluation and treatment.. Diving and hyperbaric medicine. 2018; 48 (3): p.186-193. doi: 10.28920/dhm48.3.186-193 . | Open in Read by QxMD
  5. Cooper JS, Hanson KC. Decompression Sickness. StatPearls. 2021 .
  6. Kalentzos VN. Cutis marmorata in decompression sickness. N Engl J Med. 2010; 362 (23): p.e67. doi: 10.1056/nejmicm0909444 . | Open in Read by QxMD
  7. Walls R, Hockberger R, Gausche-Hill M. Rosen's Emergency Medicine - Concepts and Clinical Practice. Elsevier Health Sciences ; 2013
  8. Mirza S, Richardson H. Otic barotrauma from air travel. The Journal of Laryngology & Otology. 2005; 119 (5): p.366-370. doi: 10.1258/0022215053945723 . | Open in Read by QxMD
  9. Recommended Practices: Green Tobacco Sickness. https://www.cdc.gov/niosh/docs/2015-104/pdfs/2015-104.pdf?id=10.26616/NIOSHPUB2015104. Updated: March 27, 2015. Accessed: December 15, 2021.
  10. Medical Management Guidelines for Ammonia. https://wwwn.cdc.gov/TSP/MMG/MMGDetails.aspx?mmgid=7&toxid=2. Updated: January 12, 2017. Accessed: December 15, 2021.
  11. Gentges J, Schieche C. Electrical injuries in the emergency department: an evidence-based review.. Emerg Med Pract. 2018; 20 (11): p.1-20.
  12. Burn Incidence and Treatment in the United States: 2016. http://ameriburn.org/who-we-are/media/burn-incidence-fact-sheet/. Updated: January 1, 2020. Accessed: November 23, 2020.
  13. Workplace Injury & Fatality Statistics. https://www.esfi.org/workplace-injury-and-fatality-statistics. Updated: January 1, 2020. Accessed: November 23, 2020.
  14. Davis C, Engeln A, Johnson EL, et al. Wilderness Medical Society Practice Guidelines for the Prevention and Treatment of Lightning Injuries: 2014 Update. Wilderness Environ Med. 2014; 25 (4): p.S86-S95. doi: 10.1016/j.wem.2014.08.011 . | Open in Read by QxMD
  15. How Dangerous is Lightning?. https://www.weather.gov/safety/lightning-odds. . Accessed: December 11, 2020.
  16. Ritenour AE et al.. Lightning injury: A review. Burns. 2008; 34 (5): p.585-594. doi: 10.1016/j.burns.2007.11.006 . | Open in Read by QxMD
  17. Sanford A, Gamelli RL. Lightning and thermal injuries. Elsevier ; 2014 : p. 981-986

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