THIS MONTH IN AEROSPACE MEDICINE HISTORY
Seventy-Five Years Ago in October 1939
breathing rate nor R wave amplitude of the ECG was affected. A decrease in the heart rate, an increase in the degree of sinus arrhythmia, Danger of carbon monoxide at altitude (Aero Medical Research Unit, Air and a considerable augmentation of the amplitude of the T wave are Corps, Materiel Division, Wright Field, Dayton, OH): “The toxicity of carnewly observed biomagnetic effects. The influence of strong magnetic bon monoxide at ground levels has been thoroughly investigated and fields on electrical processes in living matter is stressed… our knowledge of its effects on man is fairly complete. There is a scarcity “Since the head of the animal is located in a strong magnetic field, of information however on the tolerance of CO at high altitudes and the consideration must also be given to magnetically induced changes in literature is particularly lacking on accurate quantitative data on the bevagal stimulation which could be eliminated by partial resection of the havior of this gas at reduced atmospheric pressures and the permissible vagus nerve. concentrations in aircraft compartments operating at great heights. “The effect of a magnetic field on the myocardium appears to be a “Our concern about carbon monoxide poisoning at high altitudes is typical example for events in which the magnetic properties of matter fully justified when one realizes that even a small loss in oxygenare not of first importance. The close coupling of electrical and magcarrying power of blood already impoverished of this gas is likely to pronetic fields requires constant consideration of the influence of an exterduce the dangerous symptoms of oxygen lack. Moreover, the absence of nal magnetic field on all electrical properties of living tissue, including high concentrations of CO in airplanes, at ground levels, is no justificacerebral electrical processes… tion to suppose that dangerous values will not exist at high altitudes. It “The results of this study indicate a pronounced influence of strong is probable that the CO found in the motor exhaust, with increasing almagnetic fields on electrical processes in living matter. A cautious aptitudes, remains constant or even increases, for the combustion in most proach to systematic human exposure to magnetic fields may be warmotors becomes poorer with increase in altitude. Furthermore, even ranted” (1). though the quantity of carbon monoxide should remain constant, the [Editor ’s note: This research is of particular historical interest today, as volume of exhaust gas increases with decrease in pressure and increases the U.S. Navy’s newest aircraft carrier, the USS Gerald R. Ford (CVN 78), the possibility of mixing the exhaust gases with the inspired air… is to: being constructed “The deleterious effects of CO on the human organism are by the Ingenta reDelivered Guest User using the Electromagnetic Aircraft Launch System (EMALS) to replace the older steam technology catapults.] sult of a dual action of this gas on the blood. In the fi rst place it comIP: 5.189.200.16 On: Sun, 26 Jun 2016 04:12:50 bines with hemoglobin to the exclusion of oxygen and this reduces the Copyright: Aerospace Medical Association Twenty-Five Years Ago in October 1989 uptake of this gas by the blood. In the second place it hinders the use Is Freon really that bad? (Aviation Medicine Department, Naval Hospital of that oxygen which does succeed in getting into the blood by interCorpus Christi, TX): “Freon 113 [trichlorotrifluoroethane (TCTFE)] is fering with its liberation from oxy-hemoglobin… not usually considered a toxic chemical and is not generally included “Although the data represented here [see Fig. 1] are for equilibin toxicology text lists of dangerous chemicals. However, during one rium conditions, which are reached only after several hours or more of 7-year period, the U.S. Navy recorded 38 freon-related mishaps, innormal breathing, the accelerated respiration at high altitudes will cluding 16 chemical burns and 22 inhalation injuries. Several deaths cause a more rapid rate of CO absorption so that these conditions will were also recorded. Part of the problem seems to be that freon comoccur much sooner… pounds are excellent degreasing and cleaning agents. Consequently, “From the foregoing discussion, it will be apparent that concentrathey are widely and inappropriately used by aviation ground crews tions of carbon monoxide which are innocuous at set level become danfor this purpose. Such use usually presents no problem, except when gerous at even moderate altitudes and it is imperative that not a trace of the agent is used in small, closed, unventilated areas… this gas should be permitted to exist in airplane compartments” (2). “The Navy has established definite guidelines for those authorized to use freon. These guidelines include 1) familiarization with the problem, Fifty Years Ago in October 1964 including reading and heeding all container label precautions; 2) the reCardiac effects of strong magnetic fields (U.S. Naval School of Aviation quirement that use of such solvents be restricted to well-ventilated areas Medicine, Pensacola, FL): “Man may be exposed to strong magnetic fields with forced ventilation; 3) the use of forced ventilation or breathing equipover prolonged periods of time if plans to apply such fields for reasons of ment in enclosed or unventilated areas; 4) the requirement that only a technical nature in future space ships are realized. Experiments with authorized personnel be permitted to use freon in enclosed or consubhuman primates are necessary in preparation for systematic investifined areas, and then only under close supervision; 5) the use of gation of possible effects of such fields on man. A study of the perforappropriate protective equipment, including goggles, gloves, and promance of the heart in a strong magnetic field is of special interest. tective clothing by those exposed to liquid freon; 6) the admonition “Electrocardiograms of four monkeys were recorded during exposure not to expose freon to high temperatures, open flames, or ultraviolet of the animals to magnetic fields of 20,000 to 70,000 gauss. Neither radiation, because of the possibility of producing decomposition products; 7) training and education programs as to the hazards of freon; and 8) consultation with local aeromedical personnel or preventive medicine units for specific guidelines” (3). REFERENCES 1. Beischer DE, Knepton JC. Influence of strong magnetic fields on the electrocardiogram of squirrel monkeys (Saimiri sciureus). J Aerosp Med 1964; 35:939–44. 2. Heim JW. The toxicity of carbon monoxide at high altitudes. J Aviat Med 1939; 10:211–5. 3. Voge VM. Freon: an unsuspected problem. Aviat Space Environ Med 1989; 60(10, Suppl.):B27–8.
Fig. 1. Curves showing the variation in arterial oxygen saturation at different altitudes for various concentrations of carbon monoxide. From Fig. 2 in the original article.
1066
This column is prepared each month by Walter Dalitsch III, M.D., M.P.H. Most of the articles mentioned here were printed over the years in the official journal of the Aerospace Medical Association. These and other articles are available for download from Mira LibrarySmart via https:// submissions.miracd.com/asmaarchive/Login.aspx. Reprint & Copyright © by the Aerospace Medical Association, Alexandria, VA. DOI: 10.3357/ASEM.4143.2014
Aviation, Space, and Environmental Medicine x Vol. 85, No. 10 x October 2014
Seventy-Five Years Ago in October 1939
breathing rate nor R wave amplitude of the ECG was affected. A decrease in the heart rate, an increase in the degree of sinus arrhythmia, Danger of carbon monoxide at altitude (Aero Medical Research Unit, Air and a considerable augmentation of the amplitude of the T wave are Corps, Materiel Division, Wright Field, Dayton, OH): “The toxicity of carnewly observed biomagnetic effects. The influence of strong magnetic bon monoxide at ground levels has been thoroughly investigated and fields on electrical processes in living matter is stressed… our knowledge of its effects on man is fairly complete. There is a scarcity “Since the head of the animal is located in a strong magnetic field, of information however on the tolerance of CO at high altitudes and the consideration must also be given to magnetically induced changes in literature is particularly lacking on accurate quantitative data on the bevagal stimulation which could be eliminated by partial resection of the havior of this gas at reduced atmospheric pressures and the permissible vagus nerve. concentrations in aircraft compartments operating at great heights. “The effect of a magnetic field on the myocardium appears to be a “Our concern about carbon monoxide poisoning at high altitudes is typical example for events in which the magnetic properties of matter fully justified when one realizes that even a small loss in oxygenare not of first importance. The close coupling of electrical and magcarrying power of blood already impoverished of this gas is likely to pronetic fields requires constant consideration of the influence of an exterduce the dangerous symptoms of oxygen lack. Moreover, the absence of nal magnetic field on all electrical properties of living tissue, including high concentrations of CO in airplanes, at ground levels, is no justificacerebral electrical processes… tion to suppose that dangerous values will not exist at high altitudes. It “The results of this study indicate a pronounced influence of strong is probable that the CO found in the motor exhaust, with increasing almagnetic fields on electrical processes in living matter. A cautious aptitudes, remains constant or even increases, for the combustion in most proach to systematic human exposure to magnetic fields may be warmotors becomes poorer with increase in altitude. Furthermore, even ranted” (1). though the quantity of carbon monoxide should remain constant, the [Editor ’s note: This research is of particular historical interest today, as volume of exhaust gas increases with decrease in pressure and increases the U.S. Navy’s newest aircraft carrier, the USS Gerald R. Ford (CVN 78), the possibility of mixing the exhaust gases with the inspired air… is to: being constructed “The deleterious effects of CO on the human organism are by the Ingenta reDelivered Guest User using the Electromagnetic Aircraft Launch System (EMALS) to replace the older steam technology catapults.] sult of a dual action of this gas on the blood. In the fi rst place it comIP: 5.189.200.16 On: Sun, 26 Jun 2016 04:12:50 bines with hemoglobin to the exclusion of oxygen and this reduces the Copyright: Aerospace Medical Association Twenty-Five Years Ago in October 1989 uptake of this gas by the blood. In the second place it hinders the use Is Freon really that bad? (Aviation Medicine Department, Naval Hospital of that oxygen which does succeed in getting into the blood by interCorpus Christi, TX): “Freon 113 [trichlorotrifluoroethane (TCTFE)] is fering with its liberation from oxy-hemoglobin… not usually considered a toxic chemical and is not generally included “Although the data represented here [see Fig. 1] are for equilibin toxicology text lists of dangerous chemicals. However, during one rium conditions, which are reached only after several hours or more of 7-year period, the U.S. Navy recorded 38 freon-related mishaps, innormal breathing, the accelerated respiration at high altitudes will cluding 16 chemical burns and 22 inhalation injuries. Several deaths cause a more rapid rate of CO absorption so that these conditions will were also recorded. Part of the problem seems to be that freon comoccur much sooner… pounds are excellent degreasing and cleaning agents. Consequently, “From the foregoing discussion, it will be apparent that concentrathey are widely and inappropriately used by aviation ground crews tions of carbon monoxide which are innocuous at set level become danfor this purpose. Such use usually presents no problem, except when gerous at even moderate altitudes and it is imperative that not a trace of the agent is used in small, closed, unventilated areas… this gas should be permitted to exist in airplane compartments” (2). “The Navy has established definite guidelines for those authorized to use freon. These guidelines include 1) familiarization with the problem, Fifty Years Ago in October 1964 including reading and heeding all container label precautions; 2) the reCardiac effects of strong magnetic fields (U.S. Naval School of Aviation quirement that use of such solvents be restricted to well-ventilated areas Medicine, Pensacola, FL): “Man may be exposed to strong magnetic fields with forced ventilation; 3) the use of forced ventilation or breathing equipover prolonged periods of time if plans to apply such fields for reasons of ment in enclosed or unventilated areas; 4) the requirement that only a technical nature in future space ships are realized. Experiments with authorized personnel be permitted to use freon in enclosed or consubhuman primates are necessary in preparation for systematic investifined areas, and then only under close supervision; 5) the use of gation of possible effects of such fields on man. A study of the perforappropriate protective equipment, including goggles, gloves, and promance of the heart in a strong magnetic field is of special interest. tective clothing by those exposed to liquid freon; 6) the admonition “Electrocardiograms of four monkeys were recorded during exposure not to expose freon to high temperatures, open flames, or ultraviolet of the animals to magnetic fields of 20,000 to 70,000 gauss. Neither radiation, because of the possibility of producing decomposition products; 7) training and education programs as to the hazards of freon; and 8) consultation with local aeromedical personnel or preventive medicine units for specific guidelines” (3). REFERENCES 1. Beischer DE, Knepton JC. Influence of strong magnetic fields on the electrocardiogram of squirrel monkeys (Saimiri sciureus). J Aerosp Med 1964; 35:939–44. 2. Heim JW. The toxicity of carbon monoxide at high altitudes. J Aviat Med 1939; 10:211–5. 3. Voge VM. Freon: an unsuspected problem. Aviat Space Environ Med 1989; 60(10, Suppl.):B27–8.
Fig. 1. Curves showing the variation in arterial oxygen saturation at different altitudes for various concentrations of carbon monoxide. From Fig. 2 in the original article.
1066
This column is prepared each month by Walter Dalitsch III, M.D., M.P.H. Most of the articles mentioned here were printed over the years in the official journal of the Aerospace Medical Association. These and other articles are available for download from Mira LibrarySmart via https:// submissions.miracd.com/asmaarchive/Login.aspx. Reprint & Copyright © by the Aerospace Medical Association, Alexandria, VA. DOI: 10.3357/ASEM.4143.2014
Aviation, Space, and Environmental Medicine x Vol. 85, No. 10 x October 2014
