Introduction

The process of decontamination should be viewed as a non-linear spectrum of activities that progress from scene evacuation and clothing removal to full body showering designed to quickly limit a patient’s exposure and the toxicity that follows from contamination. Although an essential procedure, the actual act of performing decontamination should not delay other lifesaving interventions.¹¹

The need for and type of decontamination performed varies depending on the nature of the release, availability of resources, number of victims, capability of responding and receiving personnel, environmental conditions, exhibited signs and symptoms, initial toxicology information, and perceived patient needs and desires. When executed, it should be performed upwind, uphill, and at enough distance away from the release location to prevent recontamination.

The decision on which method or methods of decontamination to perform becomes more challenging when the initial identification of the responsible agent is unknown, victims present with varying signs and symptoms of exposure, or the sheer number of individuals seeking care overwhelms the local capability. As a result, a one-size-fits-all approach to decontamination is insufficient; rather it should include a flexible cadre of tools and approaches that can be scaled accordingly. Under certain circumstances, self-evacuation, wiping visible contaminants from skin and clothing, and personal showering at home may be all that is needed (self-care). Other types of incidents may require varying combinations of self-care, victim clothing removal at the scene and mass washing (gross decontamination), and/or thorough soap and water showering at the hospital (technical decontamination).^4,8,10–12

In general, removing and bagging a victim’s clothing eliminates much of the contaminant (depending on the extent of clothing worn at the time of exposure) and minimizes the risk of spreading the toxic agent to others. This initial step in the decontamination process should always be performed, when possible, regardless of the agent or setting. When additional decontamination is required, the patient should be thoroughly rinsed with water.^4,8,10–12

The decision to perform decontamination is often subjective, commonly undertaken without knowledge about the agent, and based on a historical premise that early intervention reduces short-term morbidity and mortality, helps prevent delayed health consequences, and protects others against unnecessary harm. This standard approach is not without risk since the procedure itself can cause injury (e.g., applying water to reactive metals produces a volatile exothermic reaction, showering in freezing temperatures causes hypothermia and mechanical injuries, and performing decontamination can exacerbate underlying psychological disorders due to the stress associated with the procedure). Objectivity to this risk-based response decision can be enhanced by taking into account the presence or absence of exposure signs and symptoms, visual evidence of contamination, location of the patient relative to the site of release, site-specific data, and any available toxicology information. This offers decontamination personnel flexibility in adopting response capabilities and decontamination methods to dynamic situations. Such risk-based decision making requires decontamination team leadership to have the knowledge, experience, and access to information necessary to make appropriate response determinations.^4,8,10–13

In this chapter, discussion will be limited to the decontamination after exposure to a hazardous substance. Issues related to regulatory standards, personal protective equipment (PPE), toxicology, and training are addressed elsewhere (see Chapter 15).

Background

Individuals may become contaminated through direct contact with hazardous substances in their various physical states (vapor, gas, mist, liquid, or solid) or from others who are already contaminated. The contamination risk is low when gases are involved because they tend to dissipate rapidly once the individual has been removed from the source. Liquids and solids (particles, dust) are more likely to cause contamination and spread to others because they tend to persist on the patient until medical attention is received.^13–15 The overall likelihood of secondary contamination is directly related to the volatility of the substance. Agents that are less volatile are more persistent and therefore more prone to remain on the contaminated victim. Chemical agents can persist on patients’ hair, skin, and clothing. If there is significant delay between exposure and symptom onset (latency), victims may be unaware of their contamination and therefore more apt to spread the hazard to others, especially if they are self-presenting to the hospital.¹⁶

In most cases of airborne releases, simply evacuating persons from the source and removing their outer clothing when possible is sufficient to prevent further exposure or injury.^13–15 Clothing can act like an occlusive dressing; failure to remove it quickly after chemical exposure may prevent the evaporation of volatile skin contaminants.⁹ In chemical mass-casualty incidents, where aerosolized substances are more commonly the causative agent, procedures geared toward detaining ambulatory victims near the scene in order to direct them through a mass showering field decontamination system (e.g., tents or ladder sprayers) can needlessly delay evacuation and treatment. This often-practiced approach may inadvertently increase the potential for harm to the victims as well as those caring for these individuals by congregating them and vital response resources in the contamination zone (“hot zone”).^13,17

Those contaminated with liquids or solids require copious skin lavage and wound irrigation with water within minutes of skin contact to minimize the degree of injury. Rinsing the patient with a high-volume, low-pressure water source dilutes, neutralizes, and helps rid the skin of reactive surface contaminants. In the case of corrosive agents, decreasing the duration of skin contact helps restore tissue to its normal pH, thereby reducing the incidence of full-thickness burns.^{13,18,20–24} Using soap to help emulsify fat soluble agents and a soft brush, sponge, or cloth to mechanically remove any remaining solid materials may also beneficial.^4,8–10,19

The intensity of chemical injury is based on a number of factors including: route of exposure, concentration and reactivity of the agent, pH, duration of skin contact, and the integrity of the skin.^{13,22,24–26} When the duration of skin contact is prolonged, the potential for tissue damage, agent absorption, and systemic toxicity is increased. Pesticides, hydrogen fluoride, and phenolic substances rapidly penetrate the skin and enter the general circulation (e.g., Malathion penetrates the skin almost immediately on contact).²⁵ Corrosives and solvents damage the outer skin layers within minutes, yet beneficial effects of decontamination by dilution have been seen even when irrigation was delayed up to 1 hour.^13,19 It appears that treatment within 1 hour of injury is critical in reducing the severity of burns, a timeline that may also be applicable to hazardous substance contamination in general.^13,18,19 Decontamination beyond this “golden hour” appears to be most beneficial in reducing the risk of secondary contamination of emergency personnel, and may offer some psychological benefit to exposed patients.

Water reacts exothermically when combined with metallic substances such as sodium, potassium, lithium, cesium, and rubidium. Other substances such as white phosphorus, sulfur, strontium, titanium, uranium, zinc, and zirconium will ignite on contact with air. If any of these uncommon sources of contamination are present or suspected, they have the potential to react with the ambient air and the moisture on the victim’s skin until they can be physically removed with forceps and secured in a container filled with mineral oil. After these exposures, despite the potential for reactivity, quickly removing the victim’s clothing and flushing them with large volumes of water should minimize the injury.²⁷

The process of decontamination for radiological agents is similar to the one used for other hazardous substances but should incorporate radiological survey instruments. Patients should have their clothing removed and double bagged with date and time of collection recorded on a radiation warning label, followed with a soap and water showering. Unstable victims, or those with life-threatening injuries, should have gross decontamination (i.e., clothing removal) performed quickly so lifesaving interventions can be offered. The presence of radioactive materials should not delay these activities.

Specialized detectors can confirm and measure the presence of radiation as well as serve as a guide to the effectiveness of the decontamination process. Not uncommonly, at least two decontamination cycles are performed in order to demonstrate a decrease in the external contamination to a level of no more than two times the background radiation level. Attempts to remove all contamination from skin may not be feasible or desirable since some radioactivity may remain trapped in the outermost layer of skin. Covering areas of residual contamination with a waterproof dressing may help limit the spread of contamination. Persistent elevated levels of radiation may be due to internal contamination.²⁹

The proper decontamination procedure for biological agents has not been established. Historically, these agents were considered non-volatile and thought not to exhibit absorption capability in the presence of intact skin. They were also believed to pose a minimal risk of re-aerosolization. This premise changed after the intentional release of anthrax using envelopes mailed through the U.S. Postal Service in 2001, in which twenty-two individuals became ill and five died from exposure to the spores.³⁰ In general, a biological agent exposure does not require decontamination, although it is worthwhile to instruct patients to remove and wash their clothing at home and take a shower. If dermal or mucous membrane contamination is suspected, the area should be thoroughly irrigated with water.

The science of decontamination is limited and rarely evidence-based, with procedural recommendations extrapolated from military guidelines and field experience. Military and fire services from several countries (Australia, Canada, Israel, Japan, the United Kingdom, and the United States) have contributed considerably to the procedural approach to the contaminated patient. However, research designed to advance knowledge on the proper care of the contaminated patient does not lend itself to placebo-controlled, double-blind studies. As a result, the advantages of using water in the decontamination process are derived indirectly from burn studies. This research demonstrated the benefits of hydrotherapy on cutaneous skin pH and clinical outcomes when experimental skin models were contaminated with harsh chemicals.^18,20–22 The urgency of decontamination after exposure is derived from measuring chemical absorption rates in animal skin models.^22,23,25 Finally, the essential role of clothing removal in the decontamination process is based in part on studies using clothed mannequins where evaporation rates and exposure levels of volatile agents are easily measured.²⁸

Initial Approach to Contaminated Patients

The primary objectives in a hazardous material incident include limiting victim exposure by quick removal from the contamination zone, containment of the hazard to prevent ongoing contact with the agent, and patient treatment (via decontamination) to minimize harm, all without jeopardizing the safety of first responders/receivers. With contamination reduction, the level of PPE required by staff can be downgraded to a point that will better facilitate patient care (preferably standard precautions).

The essential (although not necessarily sequential) approach to decontamination consists of several key steps:

Recognition of a Hazardous Material Exposure

Recognizing the necessity for decontamination is the first critical step to successfully managing a hazardous materials event. Several clues may help first responders/receivers determine that victims of an event are contaminated. These include patient history and associated complaints (e.g., eye irritation, cough, or shortness of breath), their location relative to the release, the presence of hazardous material odors or vapor clouds, identification of a constellation of signs and symptoms (i.e., toxidrome) that suggest a specific class of poisoning, observation of suspicious materials, previous warnings of a contamination event, or labels identifying contaminating agents as present in the incident area. On recognition or high suspicion of a contamination event, first responders/receivers should activate a coordinated, planned response, which rapidly removes victims from the contaminated area and the hazardous material from the victims. These steps should occur while providing for stabilizing medical care and protecting personnel.

It is also incumbent to recognize that victims may present with suspicious signs and symptoms yet no known exposure exists. In the initial aftermath of an exposure, it may be difficult to determine whether patients have actually been contaminated or are merely manifesting illness signs and symptoms that have no organic etiology. In other cases, individuals may request decontamination even if the presence of a toxic substance is unlikely.²⁹ An appropriate and timely response in a non-judgmental and professional manner may help prevent the escalation of these symptoms and their rapid spread to others (mass psychogenic illness). As a result, resources must be available for and allocated to patients who have not been truly exposed as well as for those who have.

Identification of the Contaminant

Although general decontamination measures can proceed without contaminant identification, determination of the specific agent can focus decontamination methods and make the process more efficient. In some cases, it can also increase safety for victims and staff. For example, certain metals are explosive when mixed with water; as water is the most common choice of decontamination agent, failure to identify these metals as the contaminant could prove dangerous.

The most reliable method for identifying a contaminant is to have advance knowledge of the hazardous agents present in the environment where the exposure occurred. This is feasible in the context of manufacturing, distribution, agriculture, laboratory, or research settings where chemical inventories are commonly known, as well as incidents involving properly labeled shipments of hazardous materials or those occurring at regulated industrial sites. However, in the setting of a criminal act or a release at an unregulated site, it is unlikely that first responders/receivers will have advance knowledge of the contaminant.

Detectors for various chemical and biological agents exist, but currently suffer from imperfect reliability. Recognition of a specific toxidrome is potentially the most reliable method for rapidly identifying the class to which a particular chemical contaminant belongs. Biological contaminants, by virtue of causing disease, may be more recognizable retrospectively by the presentation of victims with similar illness symptomatology; however, their usually delayed presentation may make overall recognition of a biological release event more difficult. Radiological contaminants can be easily identified by the use of radiological detectors such as Geiger-Müller counters.

If witnesses to the contamination event are able to identify the physical state of the toxic agent (i.e., solid, liquid, or vapor/gas), its container, or its associated warning placard, the decontamination and hazard identification process can be further streamlined. Resources such as poison control centers, Internet and telephone-accessed chemical databases, and government agencies can also be contacted to help guide decision making as it relates to decontamination, PPE selection, and waste disposal requirements.

Prevention of Further Contamination

A basic tenet of emergency response is ensuring scene safety; failure to ensure the well-being of personnel and other nearby persons risks the creation of additional victims. The decontamination corridor should be strategically arranged to separate contaminated persons and items from clean areas, utilities, and unprotected staff. Patient flow through the corridor should be clearly marked and supervised. Appropriate levels of PPE should be used at all times (discussed further in Chapter 15). Guidelines from several countries state that when faced with an unknown contaminant, the highest available level of PPE should be used.^32–34 Identification of the contaminant will likely allow the use of a lower level of PPE. There is no current consensus on which PPE level should be used when medical procedures are urgently indicated on contaminated patients. Studies have been performed indicating that higher-level protection may significantly impair the ability of medical personnel to perform lifesaving procedures such as airway stabilization or obtaining intravenous access for medication administration. The creation of a hospital-specific category of PPE to help maximize procedural ability while minimizing risks to hospital staff has been suggested.⁸

Stabilization of Acute Medical Conditions

The decision to provide emergent medical care (e.g., intravenous access, airway management) to a contaminated patient prior to decontamination must be balanced against the need to protect staff and their ability to provide interventional care while dressed in advanced levels of PPE. Intuitively, the sicker the patient, the greater the perceived need for emergent care. However, if the victim’s critical injuries or state of distress is a direct result of hazard exposure, the provider must don appropriate PPE prior to providing care or they themselves may become victims. This key principle is counterintuitive to the normal desire to provide immediate aid to the victim.

When appropriately trained and protected resources are available, emergent patient care can be provided simultaneously with decontamination. However, the advanced level of protection required in most decontamination scenarios dramatically affects the caregiver’s ability to render such care. In most circumstances, basic life support skills such as maintaining a patent airway, stabilizing a fracture, and controlling significant bleeding can be accomplished concurrently with providing decontamination. Advanced life support techniques, however, must often be delayed until immediately after decontamination when caregivers can wear a reduced level of protective attire (e.g., standard precautions) that allows them greater mobility, dexterity, sight, and hearing.

If a treatment cannot be provided without contaminating and therefore endangering responders and other persons, that treatment should be withheld until safety can be reasonably assured. Treatment that can be reasonably deferred should be delayed until the patient has been decontaminated.¹¹