Thorough  cooking  will  reduce  contamination  to  a  safe level so that food can be consumed. Frozen Items Food  items  stored  in  the  freeze  space  in impermeable containers (tamed frozen strawberries, for example) may be decontaminated by immersing the containers for 15 minutes in a solution of water to which 200-ppm  available  chlorine  has  been  added;  the containers are then rinsed with potable water. Food items stored in the freeze space in permeable containers  (frozen  vegetables,  for  example)  may  be decontaminated  as  outlined  earlier  for  food  packaged  in sacks  or  other  permeable  containers. Food  items  stored  in  the  freeze  space,  but  not contained  in  outer  packaging  (meat,  for  example),  must be completely thawed and thoroughly cooked before they  are  eaten. Additional  Precautions Hands should be free of contamination during the opening  operations  to  make  sure  the  contents  are  not contaminated. Opened cans of fruit jam, jelly, or similar foods must be destroyed. Opened cans of vegetables may be decontaminated by boiling the vegetables for a minimum of 15 minutes in a steam-jacketed kettle. Biological Decontamination in Food Preparation The  use  of  heat  is  the  most  practical  means  of decontaminating biologically contaminated foods. In no case should decontaminated food be consumed until it  is  pronounced  safe  by  a  medical  officer. It is recommended  that,  insofar  as  possible,  only  foods contained  in  impermeable  packages  (cans,  bottles,  jars) be  decontaminated  and  used  for  meal  preparation. Food  items  that  are  not  packaged  or  that  are packaged in permeable containers may be cooked by either  cooking  in  a  pressure-type  cooker  at  15  pounds of pressure at 250°F (or 121°C) for 15 minutes or boiling for a minimum of 15 minutes. Certain contaminated items may be decontaminated by baking. Only those recipes listed in the  Armed Forces Recipe   Service   (AFRS)   that   specify   an   oven temperature  of  400°F  and  above,  for  a  cooking  period of 30 minutes or longer, should be used to prepare baked items  from  contaminated  ingredients. 1-22 All meats except those contained in decontaminated impermeable  containers  (canned  meat  items)  must  be cooked to the well-done stage. Guidance cards in the AFRS include information on internal temperatures indicating  the  well-done  state. Biological Decontamination of Water The  detection  of  water  contamination  and  requisite laboratory  analysis  are  responsibilities  of  the  medical department.  Biological  decontamination  of  water  is  not difficult when regular water treatment facilities exist. However, more chlorine probably will need to be added during the ordinary processing of the water. If no water treatment   facilities   are   available,   water   can   be decontaminated by any of the following methods: 1. By boiling for 20 minutes 2.  By  using  iodine  tablets  coupled  with  boiling A medical officer should approve the method of decontaminating; after the decontamination process, the officer should determine whether or not the water is fit to be used. Water that has been decontaminated must be protected  against  further  contamination. DEFENSE AGAINST CHEMICAL AGENTS The United States has committed itself against initiating the use of chemical agents. However, it is necessary  to  be  prepared  against  attack  by  an  enemy using this type of warfare. A chemical agent is defined as a solid, liquid, or gas that, through its chemical properties, produces lethal or damaging effects on man, animals, plants, or material, or produces a screening or signaling smoke. Chemical   warfare   agents,   like   the   biological warfare agents, are used mainly because of their effect on  personnel,  although  some  agents  will  have  a corrosive effect on specific materials, and incendiary devices will burn most materials. These agents produce a  harmful  physiological  reaction  when  applied  to  the body externally, inhaled, or ingested. Most chemical agents cause disorganization of the functioning of the body. The  degree  of  contamination  of  the  messing  area and equipment depends on the chemical agent used and the factors involved, such as the method of delivery (vapor, light liquid, and heavy liquid), the weather, and the  various  strengths  of  contamination.