EXTERNAL AND INTERNAL CONTAMINATION DECONTAMINATION AND DECORPORATION Module XV.

EXTERNAL AND EXTERNAL AND INTERNALINTERNAL CONTAMCONTAMIINATNATIIONON

DECONTAMDECONTAMIINATNATIIONON AND AND DECORPORATDECORPORATIIONON

EXTERNAL AND EXTERNAL AND INTERNALINTERNAL CONTAMCONTAMIINATNATIIONON

DECONTAMDECONTAMIINATNATIIONON AND AND DECORPORATDECORPORATIIONON

Module XModule XVV

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IIntroductıonntroductıonContamination rContamination riskisk

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Contamination sContamination sourceources:s:rreactor eactor aaccidentsccidents

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Goiania Goiania aaccidentccident

Area of contamination: 4 000 000 m2

249 contaminated (137Cs) persons, 129 with internal contamination, 4 deaths

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External External rradionuclideadionuclide contaminationcontamination

External contamination: radioactive material, as dust, solid particles, aerosols or liquid, becomes attached to victim’s skin or clothes

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External External contamination contamination mmeasurementeasurement

Proper monitoring of patient can detect and measure alpha, beta or gamma emitters; radiation type depends on isotope in contaminant

Alpha Monitor

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Radiological surveyRadiological survey

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Radiological triageRadiological triage

112 000 persons monitored in Goiania at olympic stadium

QuickQuick `frisk `frisk’’

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DDecontamınatıonecontamınatıon

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Decontamination Decontamination ttechniquesechniques

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Decontamination Decontamination proceduresprocedures

Start with gentle stream of warm water Use mechanical action of flushing and/or

friction of cloth, sponge or soft brush For showering, begin with the head and

proceed to the feet Keep materials out of eyes, nose, mouth

and wounds Use waterproof draping to limit spread Cover uncontaminated area with plastic

sheet and tape edges

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Decontamination techniques• Use single inward movements or circular motion • Then rinse area with tepid water and gently dry using the same motions• After drying, remonitor skin to determine effectiveness of decontamination

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Decontamination procedures:Decontamination procedures: body orifices body orifices

Consideration:Consideration: Orifices need special attention because

absorption of radioactive material more rapid than through skin

Procedures:Procedures: Oral cavity: brush teeth with toothpaste, ,

frequently rinse mouth with 3% citric acid Pharyngeal region: gargle with 3% H2O2

Swallowed radioactive materials: gastric lavage

Nose: rinse with tap water or physiological saline

Mouth

Nostrils

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Eyes

Ears

Procedures:Procedures:

•Eyes: rinse by directing stream of water or physiological saline from inner to outer canthus while avoiding contamination of nasolacrimal gland

•Ears: - rinse externally with water

- rinse auditory canal using ear syringe

Decontamination procedures:Decontamination procedures: body orifices body orifices

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Useful therapeutic agents for skin decontamination-I

Common soap or detergent solution for skin and hair; low acidity (pH ~5) recommended

Chelating agents: solution of EDTA 10% for skin or hair

contamination with transuranium, rare earth and transition metals

DTPA 1% in aqueous acid solution (pH ~4) for washing skin after contamination with transuranics, lanthanides or metals (cobalt, iron, zinc, manganese)

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Useful therapeutic agents for skin decontamination-II

Potassium permanganate, 5% aqueous solution should be used carefully not recommended for face, natural orifices and genital regions use when conventional washing ineffective follow with application of reducing agent, then rinse with water

Hydroxylamine or sodium hyposulfite, 5% freshly prepared aqueous solutions reducing agents - apply after KMn04 or Lugol, then wash with

water

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Useful therapeutic agents for skin decontamination-III

Antiphlogistic topical ointment: To be applied for fixed contamination,

especially useful for contamination of fingers Isotonic saline solution for eyes Isotonic 1.4% bicarbonate solution for

removing uranium from body Lugol solutions for iodine contamination Acetic acid solution (pH 4 to 5) or simply

vinegar for decontamination of 32P

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Internal Internal contamination contamination

Occurs when people ingest, inhale, or are injured by radioactive material

Metabolism of non-radioactive analogue determines radionuclide’s metabolic pathway

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Extent of Extent of hhazardazard

Factors determining extent of contamination hazard:

Amount of radionuclide(s) Energy and type of radiation Biological and radiological half-life Critical organ Chemical and physical properties of

radionuclide

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Inhalation:Particularly likely with explosion or fire

Particle characteristics important (size, chemical composition, solubility in body fluids)

Ingestion:Critical for general public after accidental environmental

release

Wound contamination

Absorption

In order of decreasing frequency, contaminants enter the body by four principle routes:

Intake routesIntake routes

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Contamination sourcesContamination sources in in nuclear accidentsnuclear accidents

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Inhalation Inhalation

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InhalationInhalation

Fate of inhaled particles dependent on physicochemical characteristics

Soluble particles (3H, 32P, 137Cs) absorbed directly into circulatory system

Insoluble particles (Co, U, Ru, Pu,, Am) are cleared by lymphatic system or by mucociliary apparatus above alveolar level. Most secretions reaching pharynx swallowed, enter gastrointestinal system

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Deposition and Deposition and cclearance learance from from rrespiratory espiratory ttractract

Contaminant's particle size determines deposition in respiratory tract Particles <5 microns in diameter may reach alveolar area Particles >10 microns too large to pass into alveoli, deposited in

upper airways

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Ingestion Ingestion

All swallowed radioactive material enters digestive tract

primarily from contaminated food and water secondarily from respiratory tract

Absorption from the gastrointestinal tract depends on

chemical make-up and solubility of contaminant

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Ingestion Ingestion

• GI absorption <10% for most elements• Elements of high absorption:

• radium (20%)• strontium (30%)• tritium (100%)• iodine (100%)• caesium (100%)

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Wound contamination Wound contamination

Open fracture demonstrates wound contamination with depleted uranium shrapnel

•Any wound considered contaminated until proven otherwise

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PercutPercutaanneeous ous absorptionabsorption

Generally, radionuclides do not cross intact skin, so uptake by this route does not occur

Most important exceptions are: tritium, iodine, caesium

Skin wounds, including acid burns, abrasive scrabbing, create portal for particulate contamination to subcutaneous tissue, bypassing epithelial barrier

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Distribution and depositionDistribution and deposition

Iodine

Uranium

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Diagram of intake, metabolism and excretion of

radionuclides

MetabolismMetabolism

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Internal Internal contamination contamination measurement measurement : : ddirect irect mmetethhodsods

Thyroid uptake systemWhole body counters

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Indirect cIndirect contaminationontamination mmeasurementeasurement

Indirect measurement of contamination includes nasal swipes to determine respiratory intake of radioactive aerosols, and also urine and faeces sampling to establish internal contamination

Alpha and beta emitters, the most hazardous internal contaminants, detected through bioassay sampling

Accurate bioassays require carefully executed sampling over time and knowledge of type and time of contamination

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Bioassay sampling

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Managment of Managment of iinternal nternal ccontaminationontamination

First Action Life threatening conditions have priority

over considerations of radioactive exposure or contamination. Attention to vital functions and control of haemorrhage take priority

Contamination levels almost never serious hazard to personnel for time required to perform lifesaving measures and decontamination

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Treatment of Treatment of iinternal nternal ccontaminationontamination

Treatment procedures: the sooner started, the more effective

In practice, initial treatment decisions based on accident history rather than careful dose estimates

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Basic Basic pprinciples of rinciples of ttreatmentreatment

reduce absorption and internal deposition

enhance excretion of absorbed contaminants

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Current methods Current methods ofof treatment treatment of of internal contaminationinternal contamination

- Saturation of target organ e.g. potassium iodide for iodine isotopes- Complex formation at site of entry or in body fluids followed by rapid excretion, e.g. DTPA for Pu isotopes- Acceleration of metabolic cycle of radionuclide by isotope dilution, e.g. water for 3H- Precipitation of radionuclide in intestinal lumen followed by faecal excretion e.g. barium sulphate administration for 90Sr- Ion exchange in gastrointestinal tract, e.g. prussian blue for 137Cs

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Diluting Diluting aagents:gents:wwater for ater for tritium - tritium - 33HH

Single exposures are treated by forced fluid intake:

Enhanced fluid intake e.g. water, tea, beer, milk has dual value of diluting tritium and increasing excretion (accelerated metabolism)

Biological half-life of tritium - 10 days Forcing fluids to tolerance (3-4 L/day)

reduces biological half-life to 1/3-1/2 of normal value

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137Cs - physical half-life Tp=30 years; biological half-life in adults average Tb=110 days, in children 1/3 of this

Prussian blue effective means to reduce body's uptake of caesium, thallium and rubidium from the GIT

Dosage of prussian blue: one gram orally 3x daily for 3 weeks reduces Tb to about 1/3 normal value

Ion Ion eexchange:xchange:pprussian russian bblue for lue for 137137CsCs

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Ca-DTPA is 10 times more effective than Zn-DTPA for initial chelation of transuranics. Must be given as soon as possible after accident

After 24 hours, Ca-DTPA and Zn-DTPA equally effective

Repeated dosing of Ca-DTPA can deplete body of zinc and manganese

Chelation Chelation aagents:gents:DTPA for heavy metals and

transuranic elements

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1 g iv. or inhalation in a nebulizer

Initially: 1 g Ca-DTPA, repeat 1 g Zn-DTPA daily up to five days if bioassay results indicate need for additional chelation

Pregnancy - First dose Zn-DTPA instead of Ca-DTPA

Dosage of Ca-DTPA and Dosage of Ca-DTPA and Zn-DTPAZn-DTPA

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Additional chelating agentsAdditional chelating agents

Dimercaprol (BAL) forms stable chelates, and may therefore be used for the treatment of internal contamination with mercury, lead, arsenic, gold, bismuth, chromium and nickel

Deferoxamine (DFOA) effective for chelation of 59Fe

Penicillamine (PCA) chelates with copper, iron, mercury, lead, gold. Superior to BAL and Ca-EDTA for removal of copper (Wilson’s disease)

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Treatment of uranium Treatment of uranium

contaminationcontamination In any route of internal contamination,

treatment consists of slow intravenous transfusion of 250 mL of isotonic 1.4 % sodium bicarbonate

Local treatment: for skin contamination, wash with isotonic 1.4% solution of sodium bicarbonate

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SummarySummary

Attend to life-threatening injuries first Earlier skin decontamination decreases degree of

beta burns, lowers risk of internal contamination, reduces chance of further contamination

Goal of internal contamination treatment: decrease uptake into circulatory system, decrease deposition in critical organs, increase excretory rate contaminant

Health physicists and medical specialists should advise on risks and benefits of decorporation