22.1: Electrocution

• Electrical injuries are a relatively common, complex, and potentially devastating form of trauma, both in industrial and domestic circumstances.

  • Direct current (DC): Wherein the current flowing continuously in one direction is less dangerous (200-250 milliamp intensity of the direct current is lethal).

  • Alternating current (AC): Wherein the current shows rapid alteration in direction of flow.

    • It is more dangerous than direct current (70-80 milliamp intensity of the alternating current is lethal).

• In fatal electrocution often three major events may occur, which are a threat to life and are as follows:

  • The most common is the passage of current across the heart, usually when a hand is brought into contact with a live conductor, and the body is opposite to the hand.

  • The passage of a current across the chest and abdomen may lead to respiratory paralysis from spasms of the intercostal muscles and diaphragm.

  • Current passes through the head and neck, usually in circumstances when the head of a worker on overhead power lines comes into contact with the conductor.

Effects due to the Passage of Electricity

Local Effects

• Burns and blisters: Characteristically these are seen in the skin and referred to as cutaneous electrical mark.

  • Joule burn — an endogenous thermal burn, it is due to the heat generated within the body during the flow of electric current.

• Contusions and lacerations: The wound may also be lacerated, and punctured with contusions at its margins.

  • The point of exit of current or the ‘earth’ takes place through the bare sole of the foot.

  • Singeing of hair and burning of clothes may also be noticed at the location.

• Metallization of electrical marks: When current passes from a metal conductor into the body, a form of electrolysis occurs so that metallic ions are embedded in the skin and even the subcutaneous tissues.

• Micropathological skin changes at electrocution site. The following changes are usually observed at these sites microscopically:

  • Compression of the horny layer into homogenous plaque and ironing out of the underlying papillary processes.

  • Fissures and hollows may appear between the stratum corneum and germinativum.

  • Basal cells changes are the surest sign of electrocution and the coalescence of basal cells into a star-shaped or rod-like structure in each group of the rete malpighia occurs.

  • Charring and vacuolation in the deeper cells of the epidermis and dermis, are formed by gas spaces from heated tissue fluids splitting the cells apart.

  • Metallization in the skin with occasional deposition of fine metallic particles of the conductor substance may also be seen in a few cells.

  • Epidermal nuclei are pyknotic, elongated, and aligned in a parallel or palisading fashion, often referred to as “nuclear streaming”.

• Flash or spark burns

Constitutional Effect

• Momentary shock with complete recovery if the current is small.

• Get stunned and/or may go into a suspended animation-like state and/or suffer from hemiplegia/paraplegia/loss of sight/loss of hearing/loss of speech, etc if alive.

• Immediate death when the current flown in is lethal.

Medicolegal Aspects

• Death by an electric current is usually accidental but cases of suicide and homicide have also been recorded.

• Judicial electrocution; the death penalty is carried out in the electric chair, in some states, namely: Alabama, Florida, Georgia, Kentucky, Nebraska, and Tennessee, USA.

  • The condemned person is strapped to a wooden chair, and one electrode is put on the shaven scalp and the other on the right lower leg, and the current is passed with an initial burst of 2000-2400 volts.

  • It is the second surge, of lower intensity of 500-600 volts for a longer duration which actually kills the victim. The process is repeated.

  • After five minutes, a physician checks the heartbeat. If the heart is still beating, the voltage is delivered again.

• In cases of electrocution with a wet body surface—no positive findings may be present and autopsy in such cases may be an obscure one.

22.2: Lightning

• A lightning bolt is produced when the charged under surface of a thundercloud discharges its electrical charge to the ground.

Electrical mechanisms of lightning injury

• Direct strike: Here the lightning bolt hits the victim directly.

• Contact/Conduction through another object: The victim making contact with another object which is hit by lightning and thus getting the injuries rather indirectly.

• Side flash: The bolt of lighting hits an object, such as a tree, and then jumps from the object, striking the individual nearby.

• Ground current: Once the electrical energy that is generated with lightning has flown into the body of a victim, who has been struck by the lightning, it will move towards the ground/earth and this results in injuries.

• Fifth mechanism: An injury by a weak upward streamer that does not become part of a completed lightning channel.

Cause of Death in Lightning

• Death in lightning is due to syncope/ cardiopulmonary arrest/electrothermal trauma/paralysis of the nervous system.

• Death may also be delayed in lightning victims and is usually attributed to the complications of burns.

• If the electrocution is secondary to a proximity point of impaction, survival of the victim is possible.

Postmortem Features of Lightning Death

• Arborescent marking: A fern-like injury, also known as filigree burns or lightning prints.

  • It is a patterned area of transient erythema which appears within an hour of the accident and gradually fades within 24 hours.

  • It is said to occur when a person is stuck by a negative lightning bolt is then hit by a secondary positive flashover from a nearby grounded object.

    • A second possibility is that it represents an entrance point in an individual struck by a positively charged lightning bolt.

    • A third precedent explanation of the good past is that it is due to the deposition of copper on the dermis and is also said to be due to the staining of tissues by hemoglobin from lysed red cells along the path of electric current.

• Congested membranes often with lacerations.

• Intracranial and intracerebral effusion of blood

• Patchy hemorrhage on pleura and lung surface

• Severe disruption may cause widespread petechiae.

22.3: Radiation

• Exposure to radiation can occur through two mechanisms:

  1. The First Mechanism is from a strong radioactive source such as uranium;

  2. The Second Mechanism is contamination by dust, debris, and fluid containing radioactive material.

• Factors that determine the severity if exposure:

  • Duration of time exposure,

  • Distance from a radioactive source, and

  • Shielding from radioactive exposure.

• The three types of radiation exposure include alpha, beta, and gamma.

  • The most severe exposure is gamma (X-ray radiation).

22.4: Ionizing Radiation

• IR can produce radiation injury by tearing the atoms and molecules of a substance and thereby damaging the body.

• When it passes through a living cell, it can damage the cell by tearing apart the chemical makeup of the cell. It gets injured badly, loses its ability to function, and is ultimately killed.

Sources of IR Injurious to Human Health

• Natural sources include sunlight and cosmic radiation. Sunlight includes not only visible light, which has relatively few health effects, and radiation of higher frequency, such as ultraviolet radiation.

• Intentional exposure to IR is uncommon, unusual, and very rare. It occurs when nuclear weapons (hydrogen and atomic bombs) are used as weapons of war.

• Accidental exposure occurs when a person is exposed to IR by mistake.

  • Research laboratory spillage of radioactive elements.

  • Nuclear reactor accidents.

• Therapeutic Exposure to IR

  • Medical: Diagnostic and therapeutic doses of radioactive (tracer) elements are given to the patients.

  • Industrial: In various industries especially in the watch, drug, and chemical analysis radioactive substances are used.

  • War: Nuclear weapons used by superpowers usually produce mechanical trauma, burns, and radiation sickness due to ionizing radiation.

  • Action: The ions are produced to alter the chemical structure of various enzyme systems. Fetus and child are more susceptible.