External Decontamination

Fortunately, skin or wound contamination rarely presents a life-threatening risk to either patients or health care personnel (5). The best possible scenario is decontamination in the field before transport however, following an attack with a radiologic dispersion device (ROD), patients suffering trauma will most likely present to emergency departments before undergoing external contamination. 

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Jech JJ, Berry JR, Breitenstein BD. 1983. 1976 Hanford americium exposure incident External decontamination procedures. Health Phys 45(4) 873-881. 

External decontamination procedures are designed to minimize internal contamination of patients and the individuals providing care. Radionuclides on the intact skin surface rarely produce a high enough absorbed dose to be hazardous to patients or to medical staff. However, this is not the case for chemical hazards. Prior to implementing decontamination procedures, a patient should be moved to an upwind position outside of the area of contamination. 

After stabilization and external decontamination, patients require assessment for radiation injury based on dose, specific isotope involved and the presence of internal contamination. By performing individual biodosimetry, physicians can predict the subsequent clinical severity, survivability and treatment required, as well as triage patients with subclinical or no exposure (2). The three most useful items for estimating exposure doses in a mass casualty situation are ... 

As described above (see Section VILA), soluble ChE and oxime together detoxify OP compounds. These features were combined to developed a sponge product composed of ChE (FBS-AChE and EqBChE), organophosphate hydrolase (rabbit or bacterial OPH), oxime (2-PAM or HI-6), and polyurethane foam combinations for the removal and decontamination of OP compounds from medically important biological surfaces such as skin. This is an important extension of the bioscavenger approach to external decontamination and protection against organophosphate toxicity, since currently... 

This depends on the concentration and inherent toxicity of the chemical with which a patient is contaminated and the proximity and duration of contact with the staff. Chemical agents can be present on the patient s skin, hair and clothes, all of which can be reduced by external decontamination. However, certain volatile agents may also be present in exhaled breath ( respiratory off-gassing ) and ingested chemicals may be present in vomitus, neither of which is removed by external decontamination. In these circumstances, regular rotation of staff away from the clinical areas may reduce the effects of secondary contamination. 

External radioactive contamination occurs when a radioactive isotope (e.g. debris from a nuclear explosion) is deposited on the skin and clothing. Such debris is usually in the form of a dust. This contamination can be removed by surface cleaning with soap and water (as for chemical contamination). Care must be taken during external decontamination to avoid accidental ingestion and subsequent internal contamination. 

External decontamination is essential but further assessment including whole-body monitoring may be needed following a risk assessment. Swabs, urine and faeces samples should be taken. Further management is discussed on page 353. 

Total enclosure may be in the form of a room with grilles to facilitate air flow this functions as a hood and operates under a slight negative pressure with controls located externally. Entry is restricted and usually entails use of comprehensive personal protective equipment. Ancillary requirements may include air filters/scmbbers, atmospheric monitoring, decontamination procedures and a permit-to-work system (see page 417). 

Individuals who have only received external contamination and are not otherwise injured should preferably be decontaminated at a location other than a hospital. 

Patients who show no evidence of external contamination but may have received internal contamination via a wound or inhalation or ingestion of contaminants do not need to be decontaminated prior to treatment. However, blood, vomit, urine, and feces from these patients may be contaminated and should be controlled as such. 

The possibility of contamination may be determined in the field, en route to a treatment facility, or at the treatment facility, depending on the condition of the patient. Individuals subjected only to external contamination and not otherwise injured should be decontaminated (see Section 7.3) at a location other than a hospital. Patients who show no evidence of external contamination but have likely received... 

Bennett etal. have presented a model for gaseous pollution sorption by plants. The model includes all the known factors that might have a significant effect on pollution sorption by plant leaves, including gas concentration (ambient air and internal leaf), gas fluxes (external and internal), resistance to flow (leaf boundary layer, stomatal, and internal), nature of leaf surfaces (stomatal presence, cutin, and surface properties), importance of gas solubility and thus solute concentration within the leaf, and ability of the plant to metabolize pollutants (decontaminate itself). They mentioned the reactivity of ozone as another factor to consider. They believe that surface sorption may be important, at least over short periods. They presented a possible mathematical representation of these factors, which they suggested is equivalent to the mathematical statement of Ohm s law. This material is well int ated in the review by Bennett and Hill. ... 

A decontamination plan must be based on accurate knowledge of the kinds and extent of contamination present. Prior to the removal of systems, structures, and components (SSC) other than those needed for MPF operation, the external surfaces of equipment and components, as well as walls, floors, and ceilings of rooms and areas that have been contaminated with agent, will have to be decontaminated. Three methods will be used ... 

The technology primarily treats clays because their physical and chemical properties, such as external and internal active surfaces produced by their fine crystalline structure, make them difficult to decontaminate. ARC asserts that pilot studies showed that the technology works well on perchloroethylene (PCE), xylene, phenols, and polychlorinated biphenyls (PCBs). 

External/Skin Decontamination. This entails the complete removal of clothing and gentle washing of the victim with copious amounts of lukewarm water. Mild soaps are often useful and may increase effectiveness of the removal of the offending substance. 

At TOCDF, treated scrap metal must be managed as a hazardous waste until verification testing has been accepted. Treated scrap metal is defined in the permit as metal from bulk containers, projectiles, and mortar rounds that has undergone thermal decontamination in the MPF under normal operating parameters and has no residue, internally or externally. Before shipment of treated scrap metal, residue in the interior and on... 

For the pharmaceutical and food industries, surface finish is very important to enable effective cleaning and sterilization or sanitization. Equipment should be specified with a polished internal finish, possibly with electropolishing for critical applications, and designed with a minimum of crevices or dead spaces where dirt can collect. Welds must be finished to the same standard as the plates and ground flush with the internal surface and must be pinhole and crevice free. External surface finish may also be important for visual reasons and to enable cleaning down for surface decontamination in clean room locations. 

A more convincing experiment was performed by Henderson and co-workers. Five volunteers were administered deuterated cocaine. After 2 h these individuals held drug-free hair in their hands for 30 min. All the hair became contaminated with deuterated cocaine. The concentration of deuterated cocaine in these samples was as high as 48 ng/mg of hair before decontamination of the hair samples and 11 ng/mg of hair after decontamination. Henderson and colleagues concluded, "Even after washing, the amount of deuterated cocaine in this externally contaminated hair sample was higher than that found in his hair when it was tested over the next few months."... 

The effect of concentration of cations in the externally applied cocaine solutions on the uptake of cocaine into hair is shown in Figure 8. Cocaine plus radiotracer was added (final concentration, 10 pg/mL) to each of four solutions with different sodium chloride concentrations ranging from 0 to 500 mM. Two sets of samples were studied — each set containing either Caucasian brown hair or Asian black hair. The first set was dried after exposure and prior to decontamination/analysis for cocaine. The second set was carried directly through the decontamination procedure. As seen... 

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