Decontamination

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In the broad sense of emergency management and military operations,[1] decontamination is the process of removing all hazardous material such that it does not present a threat. Such materials include hazardous biological organisms (including biological weapons, toxic chemicals (including chemical weapons, fire hazards, scattered explosives, radioactive materials (including radiological weapons), etc. Decontamination is concerned with the immediate "render-safe" situation, a term of art from explosive ordnance disposal; it is not necessarily concerned with the removal or long-term storage of materials that remain hazardous.

Biological

In biology, decontamination is the removal of microbial life forms. An item is said to be sterilized when all microbial life forms have been removed.

The purpose of sterilization is to destroy every microbial life form on inanimate items, such as surgical instruments. It is done using means that are deadly to all known microbes, such as chemicals, radiation and heat. Sterilization is not done on humans because the agents that are deadly to microbes are also deadly to humans. Some microbes that live on humans are useful and protect against other harmful microbes.

Heat

Heat may be used either to reduce a microbial populations to safe levels, as in pasteurization, or to kill all forms, as in sterilization.

Pasteurization

The purpose of pasteurization is to destroy common heat sensitive pathogens without reduction in nutrient value or change in flavor. Food is being heated to 60-70 degrees Celsius for 30min to 15sec. The higher the temperature, the less time it takes to kill the pathogens.

Boiling water canning

Heating at 100 degrees Celsius/212 degrees Fahrenheit is a common practice for canning, especially in a home or small-batch environment, acidic foods (i.e., with a pH not greater than 4.6). Most fruits, and fermented (i.e., pickled) foods are sufficiently acidic for this method. Some, such as tomatoes and figs, can be prepared in this manner after an appropriate edible acid is added. [2]

Sterilization

Current standards for complete sterilization require moist heat above the temperature of boiling water, which is provided by steam in an autoclave. The general medical standard is 121 degrees Celsius for 20 minutes or more (previously 15).

Effective sterilization for food products can take place at less stringent levels. For preserving acid foods, canning or bottling them in sterile containers, [3] which are then immersed in boiling water for a time appropriate to the amount and type of food.

For more alkaline foods, pressure canning in a home-grade autoclave is adequate. Since the food should be scrupulously clean, the microbial load is less than would be present in medical waste.

Chemical

Chemical - Bactericides are a group of chemicals that kills all bacterias, except for those in endospore stage. This group of chemicals focus on bacteria, so they may or may not be harmful to other kinds of microbes.

Fungicides are a group of chemicals made to destroy fungal spores, hyphae, and yeast.

Virucides are a group of chemicals made to inactivate viruses, especially on living tissue, where their metabolism takes place.

Sporicides are a group of chemicals made to destroy bacterial endospores. Bacteria in their endospore stage are the hardened Spartans of the microbial world. The chemicals that kill endospores will surely kill all other microbes. That's why sporicides can also be regarded as sterilants.

Radiation

Gamma radiation is used as a sterilant by breaking chromosomes. An advantage of gamma radiation is that it can be applied in a factory as a part of an automated production line. The ratio of number of items sterilized above cost of purchasing and handling of the radioactive sterilant is larger than the ratio of other sterilants. However, radioactive material isn't cheap and is very hazardous to handle. Are not to be used on small quantities and on large

Hazardous chemical decontamination

Small to moderate chemical spills may be managed with dilution or neutralization. Larger incidents, however, require both emergency evacuation and treatment of casualties.


Explosive decontamination

One of the realities of dealing with explosives is that it is not always possible to render them safe, either neutralizing in place or stabilizing such that they can be moved safely. Sometimes, the best that can be done is to burn (at best) or detonate them in place, taking steps to confine the effect and to move people and objects out of their range.

Disposing of explosives involves a wide range of variables, beginning with the type of explosives themselves, such as improvised, commercial, military, and insensitive military. Within any of these types, the explosives may be in a stable or decomposing state.

Decontaminating loose explosives

It may not be possible to move scattered pieces of explosive, but, depending on the type, it may be possible to burn them if they are not confined. If they are a type that will detonate rather than burn, the goal is to limit the damage of the explosion. It may be possible to cover them, gently, with sandbags or earth. It may be possible to deflect some of the blast with hard metal or even concrete.

Decontaminating radioactive releases

Given the need for training, organization, and possibly specialized equipment, preparedness is essential. "During the hours to days after an event begins, besides the ongoing environmental monitoring, public health response elements fall under the rubric of population monitoring, which draws upon public health surveillance, epidemiology, laboratory analyses of biologic samples, and health physics. Some states can handle events involving a small number of casualties, such as an industrial incident, but all states are likely to face major challenges in dealing with a large mass casualty event," as from a radiological weapon.

Laboratory analysis is necessary, but capabilities are limited. The instrumentation for radioactivity needed are:

  • "Bioassay are analytical technologies that detect the type and amount of radionuclides in a urine sample to determine the amount of internal radionuclide contamination that a person has received during a radiological or nuclear incident.
  • Traditional counting technologies include liquid scintillation counting to detect alpha- and beta-emitting radionuclides, alpha spectrometry to detect alpha-emitting radionuclides, and gamma spectrometry to detect gamma-emitting radionuclides in urine.
  • Mass spectrometry technologies detect the actual number of radionuclide atoms instead of the alpha, beta, or gamma emissions. "

In the United States,, a Laboratory Response Network (Radiological) at 10 or more state public health laboratories is planned. [4]

References

  1. United States Army Chemical School (1 April 2008), Multiservice Tactics, Techniques, and Procedures for Chemical, Biological, Radiological, and Nuclear Consequence Management Operations, FM03-11.21
  2. Ball Blue Book: Guide to Home Canning, Freezing & Dehydration, Alltrista Corporation, 1997, Ball
  3. boiling water is adequate for this purpose
  4. S Deitchman, C Miller, RL Jones, RC Whitcomb Jr, JB Nemhauser, J Halpin, D Sosin, T Popovic, K Uranek, MD (8 October 2010), "CDC Grand Rounds: Radiological and Nuclear Preparedness", Morbidity & Mortality Weekly Report 2010 (59(36)): 1178-1181