Tìm Kiếm Bài Đã Đăng
Col. (retired) Duong Nguyen, MC, US Army
Col. Duong Nguyen laying wreath on the Tomb of the Unknown at the national Arlington Cemtery, Virginia (June 11,1999)
Diễn Đàn Cựu Sinh Viên Quân Y
Trong bối cảnh căng thẳng và hiểm họa của một cuộc tấn công nguyên tử từ phía Bắc Hàn qua các quốc gia lân cận, cũng như khả năng của hỏa tiễn liên lục địa cộng sản Bắc Hàn có thể bắn tới một số lãnh thổ của Hoa Kỳ, chúng tôi xin giới thiệu một bài viết rất có giá trị của BS Nguyễn Dương, nguyên chỉ huy trưởng khu vực miền Tây Quân Y Hoa Kỳ về khía cạnh y tế của chiến tranh nguyên tử đối với môi trường và con người.
Ban Biên Tập
Nuclear Winter is a theory showing that a major nuclear exchange will produce a widespread darkness and cooling temperature which could wipe out the civilization and possibly the human species. About half the population of the earth could be destroyed by the direct effects of a generalized nuclear war. The rest will be affected by a starvation, secondary to climate change decimating the agriculture and the availability of fresh water, by pandemics, secondary to the lack of human immune defense system due to ionizing radiation and by the collapse of civil services. Although family physicians could not control the development of a nuclear war, they can help their patients and their families by taking an active role in civil defense and by taking necessary precautious measures to avoid radiation
Nuclear Winter was coined by Turco for a theory which indicated that nuclear war would produce so much smoke that the global climate/environment would be violently affected (1). There would be generalized darkness and widespread, drastic, long-term surface cooling caused by absorption and scattering of sunlight in upper atmosphere by smoke, dust and chemical products generated by a nuclear exchange.
Although family physicians cannot control the development of a nuclear war, they should be aware of the condition and take the very limited necessary measures to help patients and their families. The following article will briefly describe the effects of a nuclear explosion followed by a discussion of the consequences of a nuclear winter, then a review of current means to limit widespread damages.
II- Review of nuclear explosions basic effects
A- Acute effects of nuclear explosions (2.3):
1-Blast: blast injuries can be direct, indirect, like missiles from flying debris, crushing injuries from falling debris or secondary to destruction overpressures.
2-Thermal radiation (heat): injuries are flash burn, flame burn and injuries of the eyes like blindness, loss of night vision and retinal burns.
3-Nuclear radiation (4):
0-25 rems: no effects
25-199 rems: slight blood changes
200-600 rems: severe blood changes, hair loss
600-1000 rems: hemorrhage, infection, death
Radiation particles from fallout may enter the body by inhalation, ingestion and injection (through the wounds) and become an internal hazard. Internal exposure causes great concern because radiation exposure of organs and tissues from an internal source is a continuous exposure. Nucleides tent to collect in critical organs eg. 131-I concentrates in the thyroid, plutonium, strontium, cerium and barium concentrate in the bone (5).
There is no health effect of the discharged electromagnetic pulse.
B- Long-term effects of ionizing radiation (6)
Usually long-term effects refer to late changes in somatic and germinal tissues that have followed sone acute (brief) exposure to raddiation.
The main effects are:
1.cell killing: eg. abortion, corneal damage, destruction of the bone marrow which consequently suppresses the immune system hence makes patients more vulnerable to infectious diseases (epidemics).
2.cell transformation: carcinogenesis and leukemogenesis (leukemia, thyroid cancer, cervical cancer).
3.cell mutation: chromosomal damage (birth defects).
C-Psychological effects (7)
The direct changes in the central nervous system (CNS) can produce psychological symptoms eg.: generalized reduction of motivation, lethargy, fatigue, change in capacity to learn and to remember, anxiety, phobias and psychosomatic symptoms (neurosis, hypochondria).
III- Nuclear winter: a medical catastrophe.
Sagan and his team TTAPS (Turco, Toon, Ackerman, Pollack and Sagan) in 1983 released a study which predicted the possibility of an extinction of the human race following the major exchange of nuclear weapons of the superpowers.
Sagan estimates that the immediate death from blast, radiation and fires in a nuclear war is in the range from several hundred millions to 1.1 billion people. Serious injuries requiring immediate medical attention which would be largely unavoidable will be also around 1.1 billion people. Thus half of the human population on the planet would be killed or seriously injured by the direct effects of nuclear war.
B- Effects on the civilization
There will be a widespread social disruption: unavailability of electricity, fuel, transportation, food deliveries, communication and other civil services. Medical care will be absent, as public health. The decline in sanitation measures will bring epidemics.
C- Biological impacts
The burning of modern tall buildings generates large amounts of pyrotoxins such as carbon monoxide, cyanides, vinyl chlorides, oxides of nitrogen, ozone, dioxin and furans. This pyrotoxin smog might persists for months. These pyrotoxins, associated with low light levels, radioactive fallout and increase in ultraviolet radiation will likely destroy all Northern Hemisphere agriculture and wipe out global grain production. This will produce devastating human consequences: many nations in the developing as well as the developed world depend on the import of food (eg. Japan import 75% of its food). Thus large number of people would die of starvation.
The long-term surface cooling creates subfreezing temperature which limits the availability of fresh water not counting the hundred millions of dead bodies covering the frozen ground.
There are changes in the ecosystem: the widespread darkness may cause the collapse of the aquatic food chain in which sunlight is harvested by the phytoplankton and zooplankton which are the bottom of the food chain (small fish, large fish, humans and terrestrial predators).
The radiation assaults will likely produce new varieties of microorganisms, some of which might become pathogenic. With the decrease in the human defense immune system, global epidemics (pandemics) are inevitable.
IV- Optimistic view
Not all scientists agree with the nuclear winter theory, J. Orient, President of Doctors for Disasters Preparedness, dismissed it in 1988 (8). She stated that the nuclear winter theory was based on a crude computer model which neglected such details as oceans, winds and the rotation of the earth. A better model will show only a small transient drop in temperature which may damage at most one growing season.
She added that the mass starvation is not well supported by present data. In the US, one good year produces enough grain to feed the US population for 10 years and we have a four-year supply of grain in storage now. We may have a problem of access to storage because of the widespread destruction of the transportation system.
V- Management and Preventive measures
The management and preventive measures are very limited due to scarce resources (collapse of health services) after a nuclear war.
At the present time the initial management begins with a measurement of the radioactivity of the nasal mucosa, the thyroid and human secretion like urine and feces.
It is followed by a decontamination: in general, the radiological hazards to a contaminated patient and the attending medical personnel will be small. Medical or surgical treatment needed when a life is in danger should not be delayed because of possible contamination. If contamination does exist, removal of the outer clothing and shoes, in most instances, will remove 90- 95% of it. Washing the exposed areas of skin increases the removal of contamination to 99%. No special soap, detergent or acids are needed to remove fallout particles. Mild soap and water or detergent and water for 2 to 3 minutes will suffice.
1. Against blast effects: recent tests of shelters built from steel and concrete show that all persons who took refuge survive the blast. The existing subway system provide a convenient mass protection. If not available, a garage, a basement may help.
2. Against thermal radiation: any mass or space between the human body and the source of radiation can protect aginst burms. If a person is at a distance that he/she survives the blast effects, a bed sheet can protect him/her from burn injuries. Family physicians can advise their patients to wear white fabrics because light color radiates the effect of thermal radiation while dark color causes severe burns as seen in Hiroshima.
3. Against fallout radiation: recent study shows that 90% of the persons estimated to die from the effects of residual nuclear radiation could survive in a well-designed fallout shelter. Physicians and their patients should be vocal through their legislatures in demanding a viable civil defense. Switzerland spend $43 per person per year on civil defense, the U.S.S.R. about $14.50 while the U.S. a meager $0.60!
4. Radioprotectants are substances protecting against radiation insult (9). They are capable of increasing long-term survical and provide a psychological benefit to those taking the drugs.
American laboratories are testing about 4400 compounds mostly aminothiols. The most promising is WR2721 which acts by blocking early radiation induced damage at the cellular level.
Another radioprotectant is KI: I-131 is one of the most important element in fallout radiation. I-131 is water soluble and can cause cancer of the thyroid or hypothyroidism. These effects can be prevented by blocking the thyroid gland with normal non-radioactive iodine in the form of a staturated solution of potassium iodine (KI) before the person ingests the radioactive iodine. The dose is 4 drops daily of a saturated solution of KI.
Other radioprotectants under studies are glucan, levamisole, azimexon and vitamins A and E which can increase 30 days of survival in mice. One condition we have to remember is radioprotectants should be taken before radiation exposure like before a nuclear explosion or before entering a contaminated area.
Nuclear winter produces in the first few weeks:
-lack of food, fuel
-insufficient medical capabilities
-masses of dead, seriously injured
-social services collapse ALL IN THE DARKNESS OR TWILIGHT
-agricultural system collapse
-chronic food shortage
Family physicians should be aware of the devastating effects of a nuclear winter. They have to try to limit the damages as much as possible by acting through their legislatures in providing more civil defense measures and by teaching their patients and their families how to manage and avoid injuries from nuclear explosion.
I like to conclude with a quotation from Ehrlich (1983): In any large-scale nuclear exchange between the superpowers, global environment changes sufficient to cause the extinction of a major fraction of the planet and amimal species on the Earth are likely. In that event, the possibility of the extinction of Homo sapiens cannot be excluded.
Lt. Colonel Duong NGUYEN received an M.D. degree from the Faculty of Medicine, University of Saigon, South Vietnam and a M.P.H. degree from Johns Hopkins University. He completed the Family Practice Residency at Oklahoma Health Science Center, the Preventive Medicine Residency at Ft. Lewis, Washington, and the Basic Aviation Medicine Course at Ft. Rucker, Alabama. He is board certified and recertified by the American Academy of Family Physicians. He is currently at Command and General Staff College, Air Force Strategic Studies in Ft. Leavenworth, KS.
Note: The view expressed are the personal views of the author and do not necessary represent the views of the US Army or the Department of Defense.
1.Sagan, Carl. Nuclear War and Climatic Catastrophe: Some Policy Implications, Foreign Affairs, Winter 1983/84. Vol.62,#2.257-274.
2.McDermott, Frank E.. Medical Operations in Nuclear War. U.S. Army Environmental Hyglene Agency. Aberdeen Proving Grounds. Jan 1987.
3.P014 (COMPS). Fundamentals of Nuclear and Chemical Operations. US Army Command and General Staff College, Ft. Leavenworth, KS, Academic Year 1988-89.
4.Chanlett, Emil T. Enviroment Protectiong. McGraaw-Hill Book Company. 2nd Edition 1979. 431-486.
5.Allman Robert M. Long-term effects of Ionizing Radiation. Uniformed Services University of the Health Sciences. Bethesda, MD. Jan 1987.
6.Mickley, Andrew G. Psychological Effects of Nuclear Weapons. AFRRI. Jan 1987.
7.Orient, Jane M.. Medical Preparedness and Nuclear War. Civil Defense and SDI in the 1990s. Vital Speeches of the Day. April 23, 1988.
8.Jacobs Aaron I. Radioprotectants. AFRRI. July 1985.
The Physicians' Journal, Vol. 102, May 1989
(Tập San Y Sĩ - Số 102 - Tháng 5/1989)
Presentations by Duong Nguyen, MD:
1- Prevention of Maternal Transmission of Hepatitis B: Result of a new Program. Presented at the Annual Meeting of the American Public Health Association (APHA) in Anaheim, CA, Nov. 1984.
2- New Strategies for the Prevention of Hepatitis B Transmission as a Sexually Transmitted Disease. Presented at the Annual Meeting of the APHA in Washington, D.C., Nov. 1985