Autopsy & forensics

Types of injuries

Environmental deaths

Last author update: 1 July 2013
Last staff update: 18 November 2021

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PubMed search: fire [TI] autopsy, electric injuries [TI], hypothermia [TI] OR hyperthermia [TI] forensic "last 5 years"[dp]

Lindsey Harle, M.D.
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Cite this page: Harle L, Tops T. Environmental deaths. website. Accessed March 24th, 2023.
Fire deaths
Definition / general

Types of burns
  • Flame: occurs when skin is in direct contact with flame
    • Flash burn is due to sudden explosion of gas or particulate matter; produces uniform burn over all exposed skin
  • Contact: occurs when skin is in direct contact with a hot object (e.g. iron)
    • May show pattern injury reflective of the hot object
  • Radiant: occurs when skin is exposed to heat waves; produces blistering and erythema
  • Scalding: occurs when skin contacts hot liquid
    • Immersion burn: occurs commonly when child is placed in tub of hot water
    • May indicate child abuse; as child flexes to avoid water, areas of skin are spared around knees and inguinal region
    • Splash or spill burn: cased by splashing of hot liquid; usually accidental in nature
    • Burn pattern should correspond to the scene description, with more severe burns near the initial point of contact (e.g. child’s hand or head when a pot of liquid is pulled off the stove)
    • Steam burn: can cause severe laryngeal edema when inhaled
  • Microwave: occurs when skin is exposed to electromagnetic waves; usually accidental
    • Tissue with higher water content shows more severe injury (e.g. muscle burns more rapidly than fat)
  • Chemical: occurs when strong acids or alkali contact skin; can also be caused by phosphorus or phenol
    • Burns develop more slowly than those created by thermal injury
    • Alkali agents tend to cause more severe injury; are usually full thickness and appear pale and leathery
    • Acid burns usually are partial thickness and appear erythematous and erosive

Mechanism of death
  • Immediate mechanism of death due to thermal injury
    • Neurogenic shock secondary to severe pain
    • Hypovolemic shock and acute renal failure due to loss of fluid from skin
    • Toxic gas inhalation - CO (most common), cyanide, acrolein, nitrogen dioxide, hydrochloric acid
      • Often see soot in nose / mouth
      • May produce edema, mucosal necrosis of upper airway or bronchospasm
      • CO levels usually 30% - 60% in fire deaths
  • Delayed mechanism of death due to thermal injury
    • Delayed hypovolemic shock with renal failure
    • ARDS
    • Infection (pneumonia, sepsis, cutaneous)
    • Pulmonary embolus due to immobilization

Postmortem changes in charred / burned bodies
  • Pugilistic attitude: flexion of the upper extremities as the body cools
  • Does not reflect ante or perimortem body position
  • Skin / muscle splits: occur parallel to muscle fibers; can extend into body cavities
  • Should not be confused with antemortem trauma
  • Loss of fingers / toes / extremities: due to charring or loss at the scene
  • Heat epidural: blood boiling out venous sinuses produces postmortem epidural blood pooling
  • Weight and length measurements are unreliable

Classification of fire deaths
  • Death due to an intentionally set fire is generally a homicide
  • Suicidal if the individual sets him / herself on fire
  • Look for accelerants or volatiles on clothing from the decedent
  • Many fires are accidental
  • Antemortem versus postmortem burn
    • Postmortem burns may appear yellow and dry; microscopic evaluation should reveal no inflammatory reaction
    • Some postmortem burns can be impossible to distinguish from antemortem burns
Electrical injuries
Definition / general
  • 2 types of current cause death in U.S. and Europe: direct (rare, e.g. car battery or lightning) and alternating (most common, e.g., household items or downed power lines)

Ohm's law
  • V = IR or I = V/R
    • I = Current is measured in amperes
    • V= Volt is a unit charge of potential energy; the difference between a point of a circuit (e.g., a live wire) relative to a reference point (e.g., ground)
    • R= Resistance (ohms) of the flow of electrical energy through an organic or inorganic substance (conductor)
  • If a human is in contact with a live current, then the amount of energy (volts) transmitted into the person (conductor) is inversely related to the resistance at that point of contact
  • For example: decedents with moist skin are at higher risk for electrocutions than those with dry, callous skin because the latter group is more resistance to current than the former

Voltage deaths (alternating current / AC)
  • Generally, low voltage is arbitrarily considered to be < 1000 volts
    • Most U.S. households have wall outlets in the 110 to 120 volt range while the home's circuit breaker consists of twice as much voltage (e.g., 220 to 240 volt range)
    • Industrial work environments in the U.S. may have outlets in the high 400 volt range
    • Gross findings: low voltage electrocutions may leave little, if any injuries on the body
    • Death: primarily due to cardiac arrhythmia (ventricular fibrillation)
  • Generally, high voltage is arbitrarily considered to be > 1000 volts
    • Power lines can range from 10,000 to over 100,000 volts
    • High voltage arcs can emanate from power source and make contact with the victim who may be several feet away
    • Gross findings: obvious charring on the body is common in high voltage deaths
    • Death: organ damage related to thermal energy released into the body

Voltage deaths (direct current / DC)
  • Lightning is a naturally high voltage form of direct current
  • Once lightning strikes a body, the lightning blast could throw the victim several feet away from the site of initial impact
  • Fern-like skin lesions may develop on the body because the thermoelectric energy causes discoloration of the cutaneous blood vessels

Scene findings
  • At low voltage death scenes (e.g., at family dwellings), it is important to:
    • Disconnect the power source to the suspected household item that may have led to the decedent's death (e.g., hair blow dryer) or remove any unusual foreign objects in contact with electrical socket (e.g., fork or knife)
    • Collect any suspicious household items located near the body to be inspected systematically for faulty wiring or poor workmanship by a certified electrician
      • Any electrical manufacturing defect(s) found in the product may ultimately result in a nationwide recall of that product

Gross findings
  • Full inspection of the decedent's clothing (e.g., shoes, hat, gloves, pants) may offer clues regarding the location of skin lesions
  • At autopsy, especially for low voltage deaths, a careful full body (e.g., scalp, underarms, webs of the fingers / toes) inspection to find subtle skin injury
    • If inspection is negative, repeat the full body inspection again to avoid missing any injuries
    • If inspection is negative for the second time, have another forensic pathologist carefully look over the body for lesions
    • If negative for the third time and suspicion of an electrical death is high, briefly state in the autopsy report that there were no electrical injuries identified times 3 inspection attempts
  • In high voltage deaths, at autopsy, finding skin lesions are more obvious (e.g., arc / charred marks)

Histological findings
  • Thermoelectric damage in high or low voltage may lead to the display of:
    • Nuclear streaming or palisading of the epidermis
    • Steam blisters that are present in the epidermis or dermis
Temperature related deaths
  • Core body temperature below 95°F (35°C)
  • Usually due to environmental exposure
  • Increased risk in very young and very old, thin individuals, males (due to decreased subcutaneous fat)
  • Cold water exposure more rapidly fatal than cold air exposure, because water rapidly dissipates heat
  • Physiological response to cold exposure:
    • Superficial vasoconstriction
    • Shivering
    • Increased cellular metabolism (to produce heat); more efficient in infants due to "brown fat"
    • When compensatory mechanisms fail, body temperature falls linearly
  • Autopsy findings:
    • No specific findings in hypothermia; it is a diagnosis of exclusion
    • Cherry red lividity: due to accumulation of oxyhemoglobin in tissues; nonspecific (also seen in CO poisoning)
    • If individual survives for a period of time, may show hemorrhagic pancreatitis, mucosal ulceration of GI tract, pneumonia, acute tubular necrosis, cardiomyocyte necrosis
    • Paradoxical undressing: terminal hallucinations lead the individual to feel overheated despite the cold environment, causing them to undress

  • Core body temperature above 105°F (40.5°C)
  • Heat stroke is severe form
  • Occurs when body's mechanisms of dissipating heat are overwhelmed
  • Risk factors: alcoholism, atherosclerosis, obesity, certain drugs (tricyclic antidepressants, some tranquilizers, monoamine oxidase inhibitors)
  • Symptoms: hyperthermia, hot and dry skin, CNS dysfunction
  • Vasodilation occurs, leading to circulatory failure
  • If individual survives for a period of time, may develop pneumonia, acute tubular necrosis, adrenal hemorrhage, liver and myocardial necrosis and DIC
  • Autopsy findings: nonspecific; diagnosis is made based on scene investigation and antemortem signs and symptoms
  • More mild forms include heat cramps and heat exhaustion:
    • Heat cramps: due to salt depletion; skin is moist and cool, body temperature is normal
    • Heat exhaustion: due to salt and water depletion; headache, nausea / vomiting, dizziness, weakness, cramps; body temperature is normal or slightly elevated
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