Doc 0000022034

The image displays a graphic with a stylized title "THE BLACK VAULT" in white, outlined lettering against a dark background with a blue glow. To the left, there is a detailed illustration of a bank vault door, complete with a large circular dial and various mechanical components, rendered in shades of gray and metallic tones with blue highlights. The right side of the graphic contains a block of white text on a black background, detailing the origin of the document from "The Black Vault," a source of declassified government documents, specifically mentioning the "MKULTRA/Mind Control Collection" and providing a website address in yellow text. There are no photographs, handwritten annotations, official stamps, forms, diagrams, tables, redactions, or visual evidence of experimental procedures on this page. u 0 TrHS DOCUMENT CONTAINS _ll_PAGES. COPY NO. __ ,_·!_ _ OF __i__. COPIES. ELECTRIC CURRENT AS AN AGENT FOI\ PERSONNEL INCAPACITATION .. . 'j ----·-- _ Prepared by: .. 22 Oc tohl"'r 1971 _/ - -- 0 This report has been prepared by as a part o£ a Government Contract. ~he views expressed are those of -·~·-,personnel and not necessarily those of the United States Government. i ----~---~~~--~-----~~-- 0 0 TABLE OF CONTENTS Prntocol StatC'mcnt i List vf Figures and T<\bles iii Problem 1 Discus:;icn 1 L P·:>tential Applica~ions 1 II. P:1ysical Variabl~s of Electric Current 3 Ill. P-1ysiological Considerations 5 A. Effects of Electrical Current on Hurr.ans 5 IL The Human Body as an Electrical Conductor 10 C. Skin Resistance •• 11 D. Bllrns and Other Thermal Injuries 12 E. Pulsed Cur·rent l3 F. Overcoming Skin Resistance 14 G. Path of Current Flow Through the Body 15 . H. Physiological Conclusions 17 IV. Other System Factors • 20 V. Equipment State of the Art 23 VI. Recommendations 25 References 27 ii 0 0 LIST OF FIGURES Figure l Approximate Threshold of Heart Fibrillation Ha~ard for Single B ric! Current SiJ.rges (AC or DC) . 9 Figure Z Diagram of Body Area Combinations for Current Flow Through Chest J7 LIST OF TABLES Table 1 Definition of Basic Electricity Terms 3 Table II Sensation.and Effects on Heart and Respiratory Muscles of CiJ.rrents Lasting l to 30 Seconds 8 iii 0 0 ELECTRIC CURRENT AS AN -··.l AGENT FOR PERSONNEL INCAPACITATION PROBLEM To evaluate, especially from the physiologic point of view, electric current as an agent for personnel incapacitation. DISCUSSiON I. Potential Applications for Incapacitation Electric cut"rent possesses a number of possible advantages when compared. . to other proposed agents for personnel incapacitation. Controlled electric · shock offers, not necessarily simultaneously, the (allowing possibilities: Broad spectrum of i~capacitation: annoyance, fear, intimidation, pain, muscle spasm, miner burns, paralysis, suffocaticn, unconsciousness, severe burns, death. Relative 2Eedictability of physiologic effect: reliable relationship be tween dose .and responses. Conlro·.lability: of dose and on/off dmes. Directivity: with respect to person to be incapacitated and body parl(s) to be affected. EffectivenP.SS on a wide range of subjects.: re_;:ardless of dete-rmination o:t> level of consciousness. Rnpidity of incapacitation: onset of action within a second. Rapidity oi recovery: only a few seconds for the milder cff~cts. . * Safety; for b;)th the operator anct the subJect, if desired. * This page appears to be the cover page or an early page of a typewritten report. In the top right corner, there is a handwritten annotation marking the number of pages and copies. The title of the document is centered and appears in all caps: "ELECTRIC CURRENT AS AN AGENT FOR PERSONNEL INCAPACITATION". Below this, "Prepared by:" is also centered. At the bottom of the page, the date "22 October 1971" is typed, and there is a circled handwritten number "246" in the bottom right corner. There are no images, diagrams, stamps, or redactions visible on this page. to be affected. EffectivenP.SS on a wide range of subjects.: re_;:ardless of dete-rmination o:t> level of consciousness. Rnpidity of incapacitation: onset of action within a second. Rapidity oi recovery: only a few seconds for the milder cff~cts. . * Safety; for b;)th the operator anct the subJect, if desired. * Throuq,hout tr .s r~porl, subjects ilTC' a:o;sumed to be healthy, adult humans in the 45 to 90 kilogram weight range. ....I ~-----~-------·· _________ ---- ·--·- ---.--------- --- --·--- ----~- ...,._ CovertnC"ss: quiet il.nci unobtrusive, can be camo11flagC'd • .J\side from tcchnir.al details of the delivery system, th<~ only bro:td limita tions to use of c lectric current as an incapacitation agent have to do with the number of subjects and the duration of incapacit<'~tion. It is difficult to conceive of realistic circumsti\nces thi'lt would perm-it a sufe and uniform dose to be adrninistereJ to a number of subjects at one time, a !though current would be as effective for the entire group as it is for an individual. In this report, cun·E:nt is considered as an incapacitating agent' for individuals only. Elec~dc cnrrent can be quite safe for periods of incapacitation of a few seconds only; hazards become much greater if current is used to maintain incapacitation for a minute or longer, unless special techniques and pre cautions are ased. Within these limitatjons, current could be used as an incapacitating agent under virtua!Iy any circumstanc ~s. Power can be st.:.pplied from permanent supply lines, temporary generators and lines, or po:-table supplies (includ~ ing pocket-si;c;ed battery packs in some cases). Delivery systems might be' ' p~~rmanent in:; tallations, temporary traps, hand-held instruments or long- range project:le devices. Automatic controls would suffice for systems designed for trief incapacitations, but systems main~aining incapacitation for more than a. few seconds should be controll·~d by an operator who has some training in the methods of safeguarding the he a: th of the subject. -2- v II. _Physical Vilrinblcs of Electric Cnrrrnt The performance iJ.nd suitrl.bjlity of electric shock few personnel i.ncnrrl.cita tion may be affected by several variables which characterize tht! incapaci til.ting current. The more important electrical 1=arameters are voltage, current, power (or energy) and frequency. For familiarity, these and other terms used in this study are briefly defined in Table I. TABLE I .< DEFINITION OF BA2J~ LECTRICITY 'If:~ M§_ Characteristic Brief Defirut>ou ~ymbol Unit Voltage Electrical pressure or the E volt electromotive The page contains a paragraph of text stating that the report was prepared as part of a Government Contract, and that the views expressed are not necessarily those of the United States Government. There are several small, dark marks that appear to be ink blots or smudges scattered across the page. A handwritten character "i" is visible near the bottom center of the page. There are no photographs, stamps, forms, diagrams, tables, or redactions present. more important electrical 1=arameters are voltage, current, power (or energy) and frequency. For familiarity, these and other terms used in this study are briefly defined in Table I. TABLE I .< DEFINITION OF BA2J~ LECTRICITY 'If:~ M§_ Characteristic Brief Defirut>ou ~ymbol Unit Voltage Electrical pressure or the E volt electromotive force tending to move electrons, potential Current Volume of electron flow I a.rnper~ Direct Current Current that does not vary DC ampere in direction or magnitude with time Alternating Current Current that has continuous AC ampere sinusoidal variation in direc tion and magnitude with time Frequency Rate of alteration of an AC £ Hert:z; current (cycles/sec} Resistance Opposition to the flow o: di R ohm rect or a lten1a ting current Impedance Opposition to the flow oi z ohm alternating cur rent Pulsed Current Current that flows inter mittantly, but repe~tedly Energy Capacity to do work joule Power Rate of delivery of energy, p watt the product of voltage and current -3- ~-~~~-------~--______,,_.._._.~.-----;--'-. .....-- ~~---~------- 0 0 Electric cnrrC'nts arc most often supplied from battcl"ics {direct cur ·cnt) o: frorn rot~ting generators (either altcrnilting or dire-ct cnrr~r:1). The cur rent is usn;~lly carried from one !oc<'llc to another hy low rc~i~t,.ncc conduc tors, ·such 2.s non-ferrous met<'!. 1s , or by ioni:>:nd l iqnids or gases. and is prcvcntcri from leaving the desired path by high resist<lncc in~;ulators. The application :'lf current or voltngc to bailie <'lectric;J.t devices, inc:luding resistors, coils, and capacitors, permits a wide range of functions to be p~:rformed by electricity. These basic electrical ceviccs coupled with tnore complicated devices, such as vacuum tubes and transistors, form the work ing components of all electrical and ele!'"~ronic sys<.ems which generate, trans1nit, store, amplify, modulate or otherwise control electric ,;w.-r<'nt. Purposeful control of the variables of electricity can be accomplished through the use of these basic devices. For example, a coil or inductor will tend to conduct direct current and lo•.v frequency alternating cnrrent, while impeCing high frequency alternating current. Similarly, a capacitor or condenser acts as a conductor for high frequency atte rna.ting current, but impedes direct current and low frequency alternating current, The spectrum of physical and physiological effects produced by the varia tions of voltage, current and frequency is probably familiar to many read~ ers: the tingle of a mild electric shock of low amperage, the appearance of a high vott:1ge arc discharge, the accidental bur:1 This page is a table of contents from a document. It lists various sections and subsections related to electrical currents, human physiology, and equipment, along with their corresponding page numbers. There are no images, stamps, forms, diagrams, or handwritten annotations visible on the page. The text is presented in a standard, typed format, with clear headings and subheadings, indicating a structured and organized report. and low frequency alternating current, The spectrum of physical and physiological effects produced by the varia tions of voltage, current and frequency is probably familiar to many read~ ers: the tingle of a mild electric shock of low amperage, the appearance of a high vott:1ge arc discharge, the accidental bur:1 from 110 volt, 60-Hert?. "house current" or the painful shock: from the high vol·;age of an automobile ignition system. In terms of incapacitation and biological effects on living systems, current not voltage - is the most important variable of electricity. The frequency of the current may also be a factor in deter~ining the deleterious effects of electric current, especially with regard to the sensitlvity of the human heart. -4- ·~---~-------- -·--·-··--··- 0 0 III. Pl'!.Y..:iinlogical Cons"ide~~ ·~ A. Effects of Electrica 1 Cnrrent on Humans With the exception of inconsequential effects such as th~: feeling of hair. standing-on~ end, high voltages without current flow have no known effect on human well-being or performance. Polarity of a direct current or brief discharge makes no apparent difference with regard to the incapaci ta.ting effects of flowing current. As it relates to the incapacitation problem, electric ::urrent has only three significant dfe,..:.ts on human tis sues: 1. Depo1a:!"ization of nerve anri muscle tissue, -::ausing the ''firing'1 of nerve or brain cells and contraction of muscle fibers. Depolarization causes the subjective tingle, involuntary muscular contractions and several other side-efhcts of an electric shock. 2. Change in sensitivity of ce:..·tain irritable tissues, such as increased heart irritability and s~nsH:i ity to fibrillation. t Fib::-illat.ion is an t.mcoord inated ''bag-· of-worms 11 contractile activity of the heart, and is a major threat to life which may ensue when I':"lOderate electrical currents pass through the heart. Death can follow because a fibri1Jatj:ng }~art c<'!nnot pu.mp blood. 3. Heating, to the point of coagulation and burnit,g if current flow is large enough or concentrated in a small &lea, A !l three of th~ above effects could contribute, to the pain of a severe shock, ~-thoug}]~art rna~~ due to mnscl1! spasfl)..!.. "c Unless othe&wise attributed, the material present~d in this section is de· rived from Re~erence l, which also provides a biblioi;raphy of the basic publications on the physiologic effects of electric current. t In this re po~:t, fibrillation means ventricular fibrillation. u 0 Dctilil(.'d cffcctf> ci1.n be prc-dictC'd if the amperage, rout!" t·lwnugh the body, duration of current The page contains a list of figures and tables, serving as a table of contents for a document. It includes entries like "Figure 1: Approximate Threshold of Heart Fibrillation Hazard for Single Brief Current Surges" and "Table II: Sensation and Effects on Heart and Respiratory Muscles of Currents Lasting 1 to 30 Seconds". There are no photographs, handwritten annotations, stamps, forms, diagrams, or visual evidence of experimental procedures. The page also has a Roman numeral "iii" at the bottom, indicating it's a page number. this section is de· rived from Re~erence l, which also provides a biblioi;raphy of the basic publications on the physiologic effects of electric current. t In this re po~:t, fibrillation means ventricular fibrillation. u 0 Dctilil(.'d cffcctf> ci1.n be prc-dictC'd if the amperage, rout!" t·lwnugh the body, duration of current flow and frequency of the powe::- supply are known. De liberate ex~cution in an el~ctric chair is an extreme example in which approximately 10 amperes of 50 to 60 Hertz current are passed from head to both feet for longP.r than a minute. Such a lethal curr~nt canses immcd· iate nnconsciousnes s; immediate and continuous "tetanic" contr<1ction of all major mnsclcs including the heart, thereby arresting resplration and. all useful heart activity, and severe heating effects most pronounc!."cl where the ~ ?;:cial electrodes make contact with the skin. The colloquial phrase "frying in the chair" seems apt. A less drastic but equally dramatic·_~ -of electric current is in electro convulsive therapy or "shock treatment" for mente..! ilhess. In this case, 50 to 60 hertz currents on the order of 1 ampere c...re passed from one side 2 of the head to the other for one-half second or less. "!"he patient immedi ately loses consciousness and has a generalized convulsion that appears to last longer than the duration of current application. The patient usually regains cor.sciousness within a few minutes and may be physically able to walk promptly. There is likely to he residual muscular soreness and a confusional state may persist for any p<=riod of time from seconds to days. The patient retains permanert amnesia for the time of the shock and usually makes no serious objection to repeat treatments. Therapy personnel take great care to make large-area, low-resistance ele\:trical contact on both sides of ~he head to prevent current burns on the Fat1~nt' s a ca lp. It must be emphasized that cur..-ent flow, and hence all direct effect, of electro convulsive therapy, is confined to the head. Tht! depolari;dng action of the current on the brain causes convulsive stimuli to flow out to the muscles through the normal channels of the nervous sxs tem; there 1s no significant current flow through the trunk or extremities although they move violently. Only organs in the path of the current flow can be affected directly. This is why there is no risk of direct electrical interference with hcil.rt nction during properly The document is a typed page with several sections, including titles like "ELECTRIC CURRENT AS AN AGENT FOR PERSONNEL INCAPACITATION", "PROBLEM", and "DISCUSSION". There are no photographs, handwritten annotations, signatures, stamps, forms, diagrams, tables, or visual evidence of experimental procedures. There are no visible redactions or obscured content on this page. channels of the nervous sxs tem; there 1s no significant current flow through the trunk or extremities although they move violently. Only organs in the path of the current flow can be affected directly. This is why there is no risk of direct electrical interference with hcil.rt nction during properly conducted electro-convulsive therapy. - 6- 0 0 C1trrcnts passing tlnough the torso can cause spas:i<..: ?aralysis of the respiratory, back and abdominal muscles. Contin·-1ous paralysis of the respiratory muscles f0r severi'll m1nutC!s can lead :a suffocation re~1:\rdl~!SS of other consequences, The most immediate and potentially lethal threat po:ied by a =urrent passing through the chest, however, is electrical inter fcrcncc wit':1 heart activity. Tn.ble ll outlines the h:J.z.ards o£ curr&nts nppl~cd externally to the chest for several seconds. Inspection of Table II reveals several key points. For a given curr~nt level in the 0 to 3, 000 milliampere range, alternating current has greater physio logic effect and is more ha•.ardous than direct current. Fibrillation uf the heart is rarely caused by direct current regardless ui. amperage.. Vent- * ricular fibrillation is almost always fatal unless given special treatment within minutes, but hearts that have been completely paralyzed for short periods usually resume normal activity spontaneously after the current stops. This difference accounts for the apparent Faradox in the dose response relationships shown for alternating currents: other factors being equal, a current greater than 3 amperes is less likely to be immediately fatal than currents in the 80 milliampere to 3 ampere range. It must be emphas:zed that the approximations indicated by T3.ble ·rr are valid only for current applied externally acros:=: the chest and for the indicated durations. Tha voltage required to produce a given current, cf course, is highly depe;'l dent on the nature of the electrodes, skin resistance, and other factors. The fibrillation threshold rises for current durations shorter than one sec ond, at least for non- repetitive pulses of curre·.1t. Figure 1 indicat.-~s an approximate "worst case .hrcshold for fibrillation hazard in terms of the current-time factor for brief exposures to any type of current, including 60Hz AC and capacitor discharges, For shocks !.:.sting less than one second, the thresho .. d shown by Figure 1 is for constant ent:-rgy pulses of 1. 6 joule * The star.clard method of "clos('d" defibrillation ~s to apply about 300 joules o£ electrical energy in 0. 2 seconds yr less The page contains typed text and no images, handwriting, stamps, forms, diagrams, tables, or redactions. The text discusses the use of electric current as an incapacitating agent, focusing on its limitations, safety considerations, and delivery systems. It is part of a declassified CIA document related to the MKUltra collection. The page is numbered "-2-". AC and capacitor discharges, For shocks !.:.sting less than one second, the thresho .. d shown by Figure 1 is for constant ent:-rgy pulses of 1. 6 joule * The star.clard method of "clos('d" defibrillation ~s to apply about 300 joules o£ electrical energy in 0. 2 seconds yr less through large electrodes held firm- ly on th~ skin of the anterior ch.:Jl. One joule is one watt-second. -7- .I LJ&E&.LD TABLE ri SENSATION AND EFFECTS ON HF.ART AND R£SPrHAT0RY MUSCLES * OF CURREi'JTS LASTING l TO 30 SECONDS l (THRESHOLQ.§ APPROXIMATE} - Cu:rrent Sensation Heart I Resfiratory Mus (ma) Act DC ACt DC AC ,- 0-1 none non.e none none non e non~ 1-5 tingle none none n:::.ne none non e --. 5-25 pain tingLe none none slight: non contracti('ln * 25-80 pain pain none pa.ra.lysi,. slig ht no~e con traction 80-300 i pain pain fibrillation none pa-r-alysis p:u-a Lysis 3003,000 pain pain fibri ltation paralys~s paralysis par alysis j o!y•i'_ over 3, 000 pain, p:lin, paralysis paralys~s paralysis par burns burns • For cur.-en~s apph• ed externally to the chest; currents smaller than 0. I miliiam~:~n; can C"'use fibrillation i! applied directl)' tn the heart. 3 t 10-1, 000 Hertz * ~xposu.-e longer than 30 aeconds may cause fibrillation -8- -.-....... -------":""'r.'';}~~,-~;' ... - .... ~~·--. ...,......"""!,..........,._;~ ...... --,...,~---------·--~~....-.....--·----------·---~ ....... -----... -·-.-..... -. CURRF.NT !00 Ul ~ J-4 10 Q) 0. E 1"11 1 Ul Q) 100 J-4 <:.) s0. 1"11 .......~... ...... 10 E 1 1 10 100 1 10 "100 1 10 I rnic:roseconds I milliseconds I seconds DURATION OF CURRENT (Continuous, Non-Repetitive Flow} Figure l. Approximate Threshold of Heart Fibrillation Hazard for . !:ingle B de£ Current Surges (AC or DC) .1 1 -9- • -~--...... ~---- -------------------·-- -- -------- eilch. Several authorities suggest that ha~ard threshold might well be at cn0.rgy levels an order of magnitude higher than that shown; thus the thres~ 1 hold shown by Figure 1 may he quite conservative. Currents of sufficient magnitude will cause painfu! involuntary contraction of muscles as the currents pass through an extrcm.ity. The motion made by the extremity as the muscles contract will depend upon: (l) the muscle groups stimulated, and (2) the relative strengths of contraction of the various muscle groups. A person "thrown" or "knocked down" by electric shock has been rr.oved by his own muscle contract:.ons rather than any direct proJ=ulsive effect by the extremity as the muscles contract will depend upon: (l) the muscle groups stimulated, and (2) the relative strengths of contraction of the various muscle groups. A person "thrown" or "knocked down" by electric shock has been rr.oved by his own muscle contract:.ons rather than any direct proJ=ulsive effect at the current. Relatively weak movements caused by srnalt currents can be overcome by voluntary muscle control, especially in large po·.verful people. A ''no~ let~ go" current threshold can be determi ned by measuring progressively larger currents Cowing through a person's arm from an electrode grasped in his hand, up to the current at which he can no longer voluntarily release the electrode with the current flowing. The no-let-go threshold for adults is in the 6 to 3C milliampere range for 60 Hz AC. Current values will be similar for other AC frequencies in the 10 to 1, 000 Hz range, but DC currents would have to be about five times a~ 1 large for s:.milar effect. B. The Ht:.man Body as an Electrical Conductor From the standpoint of electrical shock, th~ normal human body can be con sidered as a bony framework encased in a protein gel with some lipids, all of which is permeated with an aqueous salt solutio::'l and encased i.n a water~ proof skin. The electrical resistance of organs g~.:nerally varies inversely with water content. Tissues such as blood az:d muscle display resistances in the order of 1, 000 ohms per cubic centimeter while dense bone, fat and nervous tissues have resistances sev . eral times higher. Whole body resis~ . tance, exclusive of skin, is on the order of 200-1,'000 ohms. The trunk has· a lower resistance than the extremities with their smaller cross section and high proportion of bone. Current inside the bc-dy appears to spread in a - 10- fairly uniform manner through the available volume between the point of entrance and the point of exit rather than being noticeably concentrated a long any s p·~cial low- resistar1ce path. The sldn usually presents the major resistive barrier to electric current flow. Most .::Jf the skin resistance is in the epidermis, the dry, horny outer Layer without blood vessels. Thickness of the epidermis, and hence the resistance of the skin, may vary widely between different parts of the body. Thin skin behind the knee or in the axilla may offer less than a thousand The image displays a page of a document with a title "II. Physical Variables of Electric Current" and a table labeled "TABLE I DEFINITION OF BASIC ELECTRICITY TERMS". The table contains columns for "Characteristic", "Brief Definition", "Symbol", and "Unit", listing various electrical terms like Voltage, Current, Frequency, Resistance, Impedance, Energy, and Power, along with their definitions, symbols, and units. There is a page number "-3-" at the bottom center, suggesting it is part of a larger document. No photographs, stamps, forms, diagrams, or experimental procedures are visible. the skin resistance is in the epidermis, the dry, horny outer Layer without blood vessels. Thickness of the epidermis, and hence the resistance of the skin, may vary widely between different parts of the body. Thin skin behind the knee or in the axilla may offer less than a thousand ohms resistance, especially if moist. At the other extreme, a thick, dry callous may offer resistance approaching a million ·::Jhms: Skin that is rela tively moist, such as on the palms, soles or axillae, will be more conduc 1 tive than drier skin of the same thickness elsewhere on the body. During 4 sound sleep, all skin resistance rises greatly. C. Skin Resistance 1 The major factors in electrode-to-b0dy resistance through the skin are : 1. Thickness and intrinsic moisture of the skin, as noted above. Range: about 1, 000- l, 000,000 ohms (dry contact). Z. "Wet'' or dry contact. Presence or absence of an electrolyte solu tion providing a conductive pathway between electrode and skin. "Wet" contact can be proveded by special preparations such as electrode p<l.ste or fluids such as sweat, blood, saline solution or even tapw':lter. Conversion from a dry contact to a 11wet11 one usually drops the :-esi.stance one or two orders of ma~nitude. 3. Intact or damaged skin. Any thinning, scratching or penetration of the epidermis can drastically reduce skin ~esistance. In addHion to any reduction due to a wet contact, painless, gentle sandpapering of the skin can also reduce the resistance one or two orders of magnitude. Even a· tiny penetrati-ng burn, such as that caused by a small area of contn.ct with high voltage, will cause a near-instantaneous drop in skin resistance to a - 11- _] e few hundred ohms or less. 4. Area of contact. Othc r factors being cqua 1, resistance is inversely proportional :o ihc area of contact. A targ:e area of uniforn1 ciry contact is difficult to achieve in practice. Significant and predictable reduction in r<]sistance by large area contact is ordinarily achieved only with wet con tact such as immersion of a bocl·f part or wet clothin6. 5. Pressure of contact. Increased pressure on a d~y contact with intact skin can reduce resistance, but the effect is usually not pronounced enough to cause dry electrode-to-ski!l resistances lower than 10,000 ohms until the contact pressure exceeds 10 kilograms per square centimeter. 6. Frequency of the electric power. Skin The page contains typed text discussing electrical currents and their effects. There are no photographs, handwritten annotations, signatures, stamps, forms, diagrams, or tables visible. A small, numbered annotation "-4-" is present near the bottom center of the page, along with a horizontal line that may indicate a page separator. The document appears to be purely textual, with no visual elements beyond the printed text and a pagination mark. 5. Pressure of contact. Increased pressure on a d~y contact with intact skin can reduce resistance, but the effect is usually not pronounced enough to cause dry electrode-to-ski!l resistances lower than 10,000 ohms until the contact pressure exceeds 10 kilograms per square centimeter. 6. Frequency of the electric power. Skin impedence, or total tenden cy to obstruct the flow of electric current, is inversely proportional to increases in the frequency of the applied electric power. The relationship is not safficient to lower the effective skin impedance two orders of magni tude until the power supply frequency approaches 100 kHz. This repo::t is not concerned with such radio frequency currents because 11skin effect" keeps most of the current on the body surface where it is ineffective as an incapacitating agent. 7. Skin =overing. Dry hair and most dry cloth:.ng can increase the electrode-to-body resi.;tance by millions of ohms. D. Burns and Other Thermal Injuries The heating effects of electric current are dependent upon the amount of electrical ene:-gy being dissipated per unit time in a give-n volume a£ con ductor. About four joules of electrical energy must be dissipated in a gram of water in order to heat the water one degree centigrade. In general, the temperature rise of tissue being heated by el~ctric current varies: 1) directly with the square of the cur:fent 2) directly with the resistance of the tis sue 3) directly with the time of current flow 4) inversely with the effective volume or eros s-section of the conductor - 12- Cons ide ration of these (;lets lc:Lds to the cone Ius ion that the highest temper ature rises in most cases of electrical shock will occur in the skin at one or both points of electrical contact with the body. For significant current flows, skin burns of some degree will remain a ha?..aro unless special precautions are taken to avoid high skin resistance and small effective cross-sections o£ electrical contact with the sl(in. Conversely, the large effective cross-~ection and low resistancP. of the body beneath the skin means that many amperes of current flowing for prolong ed periods would usually be required to "cook" organs other than the skin. An electric arc in air at one atmosphere has a temperature of 2500° to 3000° C and can cause local heat effects other than those due to current 1 passing through skin resistance, E. Pulsed Current Repeated The document is a typed page with no images, handwritten annotations, or official stamps. It appears to be an excerpt from a report or paper, indicated by the Roman numeral "III." at the top, followed by a section title. The content is structured as a numbered list with a single paragraph preceding it, discussing the physiolo