External Contamination and Decontamination Techniques
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Contamination; the transmission of dangerous substances (chemical, biological, radiological and nuclear agents) to the human body, objects and the environment. The subject of this paper is contamination with radioactive materials. Contaminating radioactive substances may be in solid, liquid, gas and aerosol form and may enter the human body in different ways (skin, eyes, lungs, digestive tract, injection route). The most common form of external contamination in the human body is through the percutaneous (skin).
External External Dose Exposure ”means the person's external irradiation without being contaminated with radiation sources. The difference in contamination of a patient exposed to radioactive irradiation is that there is no physical contact or contamination with any radioactive material and that it has no harmful effects on the environment. External contamination is mentioned in the presence of physical contact with radioactive material in the human body, articles or environment.
Sources of radioactive external contamination can be summarized as follows (1):
- Accidents in medical treatment units (radiotherapy, nuclear medicine),
- Nuclear reactors,
- Industrial radiation,
- Lost / stolen medical / industrial radioactive sources,
- Accidents during storage, transportation,
- Terrorism,
- Dirty bomb,
- Attack on nuclear facilities, sabotage,
- Nuclear weapons.
The most common radioactive contaminants are alpha and beta emitters. Gamma-ray emitters cause the whole body irradiation. Beta emitters can cause skin burns and scars. Alpha emitters cannot penetrate the epithelium.
The devices used for detecting and measuring radiation to determine contamination and the amount of exposure are:
- Geiger Mller (GM) meter: Surface contamination meter. It provides a radiation measurement of radioactive material on a surface, a device suitable for measuring open radioactive material. It is used for soil contamination measurement, body contamination screening and routine workplace screening. Different probes are used to measure different types of radiation.
- Ion chamber.
- Personal dosimeters.
- Film dosimeter.
- Pen dosimeter (analog & digital).
Decontamination; to ensure the safety of people, goods and the environment by removing or inactivating chemical, biological, radiological and nuclear agents from the human body, objects and environment.
Decontamination has two main purposes:
1. To reduce the dose to which the patient will be exposed by removing harmful substances from the skin and thus the severity of the effects of the radioactive agent,
2. Protecting healthy people (emergency response teams, health teams, etc.) by preventing secondary exposure.
Decontamination in the first few minutes after exposure is the most effective way of protecting the patient, and it should not be ignored that the later decontamination process may benefit the patient by reducing the dose the patient is exposed to and protect healthy people from secondary exposure.
The first rule of controlling radioactive contamination is to limit the spread of the material. This is usually achieved by controlling the entrances and exits to the contaminated area, the use of appropriate protective clothing, minimization of the amount of radioactive material emitted in the air, and personnel monitoring (2).
Patients contaminated with radiological material are generally considered not to pose a potential risk to health personnel. Therefore, medical or surgical treatment should never be postponed. The first thing to do is to take life-saving measures independent of contamination.
As a result of nuclear terrorist attacks, many contaminated patients are encountered. Most of them are contaminated, not injured. Decontamination is the medical management of the panic and informing the public. These people should not be allowed to apply to hospital emergency services at the same time and lock the system. A triage area should be established outside the emergency room.
Radiation Measurement in Workplace Control
After the completion of the daily work in the radiopharmacy laboratory are:
- Materials such as injector casing, lead bottle protector, forceps are measured with GM counter for contamination. No contamination; these materials are removed from the closet for reuse. If contamination occurs; the lead is left behind for half-life or cleaning and measuring is done until the end of contamination.
- Tc-99m milking bottle is taken from working area like laminar flow / fume hood and left behind lead.
- Using GM, laminar flow / fume cupboard walls and the entire area are measured.
Decontamination Steps (2,3)
The first step of decontamination; decontamination. Everyone should be decontaminated, whether injured or not, if exposure is suspected.
The first principle for effective decontamination is to perform decontamination as soon as possible. Early decontamination is very important for chemical agents, especially those in liquid form. Since the absorption amount of liquid agents changes in direct proportion with the contact time, the removal of the agent in a short time decreases the penetration and absorption and minimizes the effects.
- Firstly, after taking life-saving measures and stabilizing the patient clinically, the first thing to do is to remove the people from the contaminated area. Contamination control should be performed by radiation measurement. Special transport measures should be taken for contaminated patients and a “decontamination area” should be established. In general, outdoors, the opposite direction of the direction of the wind blow is preferred, but in cases where the amount of agent in the air increases (continuation of the attack, etc.), closed areas may also be preferred. Radiation detection (in and out) should be performed in this area.
- Once the person has been taken to a safe place, clothing and accessories (jewelry, watch, clasp, etc.) are completely removed (cut if possible) and hair and skin decontamination is performed. Multiple shower systems can be installed for the injured. The removed clothing and accessories are placed in a medical waste bag, labeled and stored.
- Even simply removing clothes or combing the hair usually reduces the amount of agent carried by the patient to a large extent, and in some cases even provides the necessary decontamination.
- Secondary exposure to the liquid or gaseous agent in the patient's clothing and hair may cause contamination of the surrounding healthy individuals. It is therefore important that persons and health personnel in close contact with the contaminated person wear protective equipment (masks, clothing, pair of gloves, etc.).
- A decontamination area should also be established for health personnel.
- A place where people can rest after decontamination should be provided.
Decontamination Methods
1. Physical removal.
2. Detoxification.
The first and most effective decontamination is the physical removal of the chemical agent. Detoxification is the second target, but not always possible.
Decontamination Materials
- Gloves,
- Bag,
- Decontamination drugs,
- Absorbent paper, paper towel,
- Shoe covers.
Radioactive Area Decontamination
- The radiation protection officer shall be informed and supervised,
- Radioactive area is determined by measuring with radiation monitor,
- Immediately absorbing paper is placed on the contamination area to prevent its spreading, its surroundings are determined and passages are prevented,
- Absorbing paper is removed, paper towel is wiped from outside to inside and re-measured,
- Dry area is wiped and dried from outside to inside with towel moistened with decontamination drugs,
- Cleaning is continued until the radioactivity of the area is less than 2-3 times the background count.
Wound Decontamination
In the event of exposure to most radioactive agents, removal of clothing from the wound provides a substantial decontamination, no other method is necessary. However, additional measures may be required. During decontamination, all bandages that are suspected of contamination are removed and the wounds are washed with isotonic solution or water. If there is bleeding after decontamination, the wound is bandaged again. During decontamination, the skin should not be rubbed; rubbing of the skin accelerates the penetration of the agent to the skin (2,3).
Personnel Decontamination
- The bottle of radioactive material breaks, spills and so on. In this case, everyone in the room proceeds to the door and calls for help,
- The radiation protection officer is informed and decontamination is carried out under his supervision,
- Everybody in the room is measured by using radiation monitor.
- Contaminated clothes are placed in plastic bags and waste is applied,
- Radiation measurement is done again, if contamination continues, showering is provided,
- Skin; Wash with mild soap and plenty of water, no hard brush or irritant soap,
- Body; areas are marked and quickly entered into the shower,
- Eye; rinse with plenty of water and saline, take precautions for irritation,
- Hair; It is cleaned with a mild detergent and care is taken to the eyes, ears and mouth area when washing.
Patient Management and Decontamination (2,3)
- Carefully take off the clothes and personal belongings of the injured, bag them, store them safely (contamination is reduced by 95%).
- Take biological samples from the injured (nasal smear) if possible.
- Treat foreign objects as if they were radioactive material until otherwise instructed.
- Decontamination priority:
a. First wounds, then solid skin.
b. Start at the most contaminated area.
- Replace the outer gloves after each injury.
- To minimize contamination, shave mustaches and beards with the aid of an electric machine.
- Cover non-contaminated wounds with waterproof material.
- Contaminated wounds:
a. Irrigate with sterile material.
b. After consultation with a specialist, remove contaminated debridements and store in a safe place.
- Avoid aggressive intervention.
- Change the cleaning agent frequently.
- Decontaminate scalp and intact skin with soap and water.
- Cover cleaned and dressed wounds with waterproof material.
- Additional measures may be taken for sweating the injured hands and feet (surgical gloves).
- Detect and measure after decontamination.
- Accumulate the medical devices used in sealed bags and special containers.
- Always use stretchers in the dirty area.
decontaminant for
An ideal decontaminant should be capable of removing or neutralizing or detoxifying all known agents from the human body, articles and environment. During decontamination, responsible personnel should wear protective clothing.
Properties of Ideal Decontaminant (4,5,6)
- Effective against chemical, biological, radiological and nuclear agents, toxic industrial substances, toxic industrial chemicals and new threats,
- Neutralizing all chemical and biological agents,
- Safe to use on skin, eyes and wounds,
- Able to clean the agent under the skin,
- Easy to apply,
- Ready to use,
- Fast action over a wide temperature range,
- No toxic product,
- Can be stored for a long time,
- Accessibility,
- Not to increase percutaneous absorption of the agent,
- No irritant,
- Hypoallergenic,
- It must be easily destroyed.
Substances recommended for skin decontamination:
- Water and soap,
- Dry decontaminants,
- Liquid decontaminants,
- Chemical decontaminants.
Water and soap: Liquid decontaminants are best suited for decontamination of large or uneven surfaces. The most suitable decontaminant for decontamination of health centers and equipment is soapy water. Washing using high amounts of soapy water removes the agent by hydrolysis and is also an extremely inexpensive method. It is also a convenient and practical method for emergency decontamination.
One liter of water, five milliliters of soap by putting; For decontamination suitable liquid is prepared (Approximately 1 bucket of water 3 spray). Depending on the amount of water used for decontamination, it is collected in tanks, neutralized or directly supplied to the sewer.
Dry decontaminants: All substances capable of absorbing and drying liquid agents and then removing them by means of wiping or brushing without damaging the skin can be used for decontamination of liquid agents. Clean sand, clay, baking soda, Fuller soil, dry or wet wipes are applied to the liquid agent, after absorbing the agent, it is removed from the skin. Maximum effectiveness is achieved if the absorbent is applied within the first 4 minutes after exposure. However, dry decontaminants are not suitable for wound decontamination.
Liquid decontaminants: Liquid decontaminants are available to rapidly decontaminate radioactive contamination. It can be applied directly to leather, clothing, all surfaces, plastic and glass materials, laboratory equipment. It removes radioactive particles, the resulting composition is non-toxic and is removed from the contaminated area by washing with water. It is not used for wound and eye decontamination. After application to the contaminated area, it is dried with dry and clean paper towels.
Chemical decontaminants: 0.5% sodium or calcium hypochlorite solution is used for skin decontamination and 5% for equipment decontamination. The solution should be prepared before use, should not be prepared and kept in advance. The pH of the solution should be at alkaline pH (pH 10-11). Hypochlorite solutions (bleach) are not suitable for eye and wound decontamination and may cause corneal damage and adhesions.
Post-decontamination procedures
- Record in record format,
- Investigation of the causes of contamination,
- Take necessary measures to prevent it from recurring.
Result
It is essential that health personnel first protect themselves. Protective clothing is a must. Decontamination is not a simple process. It requires a high number of staff, materials and effort. Effective decontamination has two basic principles: the shortest time and the most appropriate method. If an attack is suspected, everyone is considered contaminated and decontaminated, whether injured or not, until proven otherwise. During skin decontamination, the skin should not be rubbed, it accelerates the penetration of the rubbing agent into the skin.
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