AD-A265 924

DOT/FAA -AM93-8 Variations in Time-to-Incapacitation

and Blood Cynanide Values for Rats

Office of Aviation Medicine Exposed to Two Hydrogen Cyanide

Washington, D.C. 20591 Gas Concentrations

Arvind K. Chaturvedi

Boyd R. Endecott

Roxane M. Ritter

Donald C. Sanders

Civil Aeromedical Institute

Federal Aviation Administration

Oklahoma City, Oklahoma 73125

May 1993

Final Report z

This document is available to the public

through the National Technical Information

Service, Springfield, Virginia 22161.

U.S. Department

of Transportation

Federal Aviallon Admlnlstretlon 93-13521

93 6 15 2
NOTICE

This document is disseminated under the sponsorship of the U. S. Department of

Transportation in the interest of information exchange. The United States Government

assumes no liability for the contents or use thereof.

The use nf animals for this study was approved by the Institutional Laboratory

Animal Use Review Committee under the U. S. Department of Agriculture Animal

Welfare Act. The animals were cared for and humanely used in accordance with the

National Institutes of Health (NIH) Guide for the Care and Use of Laboratory

Animals, PHS Publication (NIH) No. 86-23, revised 1985.

* i i T
Technical Report Documentation Page

1. Report No. 2. Government Accession No, 3. Recipient's Catalog No.

DOT/FAA/AM- 93/8

4. Title and Subtitle 5. Report Oats

VARIATIONS IN TIME-TO-INCAPACITATION AND BLOOD May 1993

CYANIDE VALUES FOR RATS EXPOSED TO TWO HYDROGEN 6. Performing Organisztion Code

CYANIDE GAS CONCENTRATIONS _____________________________________________________________ I. Performing Or•anizatien Report No.

7. Author,,) Arvind K. Chaturvedi, Boyd R, Endecott,

Roxane H. Ritter, and Donald C. Sanders

9. Performing Orgmiizatln Name and Address 10. Work Unit No. (TRAIS)"

FAA Civil Aeromedica. Institute

P. 0. Box 25082 1I. Contrect orGruntNo.

Oklahoma City, OK 73125-5066

13. Type of Report end Period Covered

12. Sponsoring Agency Name and Address

Office of Aviation Medicine

Federal Aviation Administration

800 Independence Avenue, SW 14. Sponsoring Agency Cede

Washington, DC 20591

15., Supplementary Notes

This work was performed under task AM-B-92-TOX-60.

16. Abstract

It has been suggested that protectiva breathing devices protect aircraft

passengers from combustion products for 5 miin during evacuation and for 35 miin during

in-flight-plus-evacuation. Hydrogen cyanide (HCN), a combustion gas, produces

incapacitation at relatively low concentrations, and time-to-incapacitation (ti) is

an applicable index for predicting escape from a fire. Variations in tL and blood

cyanide (CN-) at specific HCN gas exposure concentrations have not been evaluated,

Therefore, t± and blood CN" at t1 for two HCN concentrations that produce 5- and 35-

min t1 were determined in male Sprague-Dawley rats. blood CN" levels as a function

of HCN exposure time were measured. Animals were individually exposed to HCN gas in

a chamber equipped with a rotating cage, and t1 was recorded as the time from

insertion of the animal into the cage until it could no longer walk. At incapacitation and at selected intervals prior to ti, rats were quickly removed from the cage

and killed for blood collection and CN- quantitation. Chamber HCN concentrations were

monitored during the exposures, For the 5-min test (mean * SD; n - 50), NICN gas - 184

1 10.0 ppm, tj - 5.1 * 0.8 min, and blood CN" - 2.3 + 0.5 pg/mL; for the 35-mun test,

HCN gas - 64 * 6.1 ppm, tj - 31.1 * 11.2 min, and blood CN" - 4.2 * 1.3 pg/mL. Blood

CN" levels increased as a function of HCN exposure time, but the blood CN" level at

the 5-mun tj was half of the 35-min blood CN" level; the HCN gas uptake rate at 184

ppm was about 3 times that at 64 ppm. These findings suggest that the blood CN" level

at incapacitation may vary substantially, depending upon the HCN exposure

concentration; an equation is proposed for predicting blood CN" levels in rats.

17. Key Words Is. oistribution Statement

Inhalation toxicology; combustion ga&/ Document is available to the public

hydrogen cyanide; time-to-incapacitation through the National Technical

blood cyanide level; hydrogen cyanide Information Service, Springfield,

uptake; animal exposure system VA 22161

19. Security Cleself. (of this report 20. Security Clessif. (of this page) 21. No. of Pages 22. Price

Unclassified Unclassified 20

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized

___ __ __ __ __ __ __ __ __ __ _ __ __ __ __ __ __ ___Mae__
rr~

Iý I

.m

cu: -r t

ýu EŽ49

4 ý t2

1; 'a
diameter; 25.0 cm V/) vertically divided into 2 equal On every day of the experiments, the chamber flowcompartments each 12.5-cm wide. The cage was rotated through atmosphere was equilibrated and stabilized and

horizontally by a 4-rpm geared motor to provide a its HCN gas concentration was determined, When the

circumferential velocity of 8.5 cm/sec. The front corn- HCN concentration stabilized at the desired exposure

partment of the cage was used for the animal tests. A level, a chamber atmosphere sample for zero min was

gasketed access-door (10.4 cm X 10.4 cm) on the front withdrawn from the access-door port for the 14CN

panel of the chamber aL the cage floor level allowed rapid analysis. Following this, the chamber fans and cage

animal insertion into, and removal from, the cage. There motor were turned off, timer was set to zero, and

were 2 fans, I on each side of the chamber; I fan was at retaining screws on the chamber access-door were rethe upper part and the other at the lower part of the moved. Then, in rapid succession, the door was opened,

chamber. These fans were for homogeneous mixing and a rat was inserted into the cage, the door was closed, and

circulation of the gas-1ir mixture in the flow-through the timer, cage motor, and fans were activated,

chamber atmosphere, There were 2 ports sealed with

rubber septa on the front panel of the chamber. Fifty rats were individually exposed to the gas at each

of the 2 concentrations to determine variations of t, and

The HCN gas and air from cylinders were mixed by of blood CN" at incapacitation. For the relative rates of

passing through a baffled cylindrical mixing tube before HCN uptake at the 2 exposure concentrations, addientering the chamber. Flow rates of the gas and air were tional rats were singly exposed for intervals less than t,;

regulated automatically using Scott model 5850E mass the exposure intervals were 1, 2, 3, and 4 min for the 5-

flow controllers attached to a Scott model 5878A power min experiments (4 rats/exposure interval), while they

supply/control unit (Scott Environmental Technology, were 2.5, 5, 10, 15, and 25 min for the 35-min tests (3

Inc., Plumsteadville, PA). The input of gas-air mixtures animals/exposure interval). At incapacitation or at the

was through a port in the top of the chamber. The entire end of each exposure interval, rats were quickly removed

chamber was installed in a fume hood into which the from the chamber and killed (by cervical dislocation) for

chamber exhaust was vented, blood collection and CN" determination.

Experimental Protocol The criterion for incapacitation was the inabilityofthe rat

Preliminary I-ICN gas concentrations for producing towalk, i.e.,when tumblingorslidingbegan, as subjectively

incapacitation at 5- and 35-min exposure times were determined by 2 individuals. The t, was recorded as the time

calculated from the concentration-t, curve described in a from insertion of the rat until it could no longer walk in the

previous study (Crane, et al., 1989). The airflow into the rotating cage. Besides the zero-min samples, chamber HCN

chamber vas established at 4 L/min; the HCN gas flow samples were collected at I and 4 min in the 5-min t, study

was adjusted to produce the estimated gas concentra- and at 1, 5, 15, and occasionally, at 30 min in the 35-min t,

tions required in the chamber. The HCN concentrations study. HCN gas measurements at these intervals were

were refined by t, measurements using 32 rats. Based on conducted to describe the gas concentration with time

these experiments, gas concentrations produced by flow during the animal exposure. Findings from these measurerates of(80 mL/min of'9239 ppm HCN + 4 L/rin air) ments indicated that the gas concentration did not signifiand (25 mL/min of 9239 ppm HCN + 4 L/rnin air) were candychangeduringtheexposure; typical concentration-time

adopted for the !- and 35-min t, study, respectively. The relationships fbr the 5- and 35-min study are illustrated in

nominal dynamic flow of gas-air mixtures at 4 L/min Figure 2. This allowed the assumption that the gas concenprevented major HCN concentration changes during tration at t, (or the end of the applicable selected exposure

the rat insertion, exposure, or removal. Initial experi- intervals) was essentially identical to that in the chamber

ments suggested that ambient 02 levels did not change sample immediately preceding incapacitation (or the expofor single rat exposures by the HCN-air mixture flows sure interval). Since the rapid removal of the exposed animal

through the chamber; therefore, 02 concentration wo, at a particular time prohibited the simultaneous manual

not monitored during the animal exposure experiments. sampling of the chamber atmosphere, the HCN gas

3
concentration at incapacitation (or the exposure inter- rate of 0.4 mL/min. The condensate (resampled at 0.8

val) was estimated by extrapolating the value of the mL/min), phosphate buffer (0.42 mL/min), air (0.6 mL/

preceding concentration to the t, (or exposure time). min), chloramine-T (0.1 mL/min), ar.l then, th. .,yriHCN exposure concentration for each experiment was dine-barbituric acid reagent (0,8 mL/min) '.. re. sequenobtained by the integration of chamber HCN concen- tially mixed and flowed through the colorimeter cell.

tration as a function of exposure time from t - 0 to t - t1 The color intensity of the reaction mixture was measured

(or exposure time) and dividing the resulting product by using a 570 nm filter; the absorption for each sample was

t, (or exposure time), i.e., registered on the recorder. The flow rates of wastes from

ft - tCdt the condenser, and from the flow cell, were 1.0 mUL/min.

E t - 0 A water blank was inserted between each of the test

ti samples. This system operated at a sampling rate of 20

samples/hour with a sample:wash ratio of 1:5. These

precautions were taken to prevent sample carryover and where i C HON n concentration in ppm and exposure achieve baseline separation on the recorder trace. Chainber atmosphere and blood samples were analyzed for

CN- immediately following the sample collection. A

Chamber HCN Gas andBlood C" stock CN- solution (100 mg/L), prepared from NaCN

Dtmerminatsons (purity: 96% by analysis), in 0.1 N NaOH was used for

Chamber HON gas concentrations and blood CN- the preparation of working standards,

levels were determined using an automated Technicon

AutoAnalyzer'" II System consisting of a sampler IV, a

2-speed proportioning pump III, a single-channel colo- For chamber HCNgas concentrations, a 17-mL sample

rimeter, and a pen recorder II (Technicon Instruments ofchamberatmospherewas manually withdrawn into an

Corporation, Tarrytown, NY). The manifold, a acid-washed and oven-dried 30-mL glass syringe from

Technicon cyanide analytical cartridge, incorporated a thte port on the access-door. The volume was immedidistillation coil. The coil was attached by a short length ately adjusted to exactly 15 mL, and then, 0.1 N NaOH

of acid-flex tubing to a distillation head and condenser, was drawn until the plunge, reached the 30-mL index.

The methodology employed was a modification of the The syringe was closed with a plastic cap, and the gasTechnicon Industrial Method No. 312-74W (Technicon, liquid mixture was allowed to equil brate on a rnechani1974). cal rocker for 5 min. Portions o' he NaOH solution

containing CN- and 5 working standards were transReagents used in the assay were: o-phosphoric acid ferred into the AutoAnalyzer sample cups for the CN-

(1,74 M); phosphate buffer (0.01 M; pH 5.2); chloram- analysis. These standards were prepared from the stock

ine-T (0.0142 M); pyridine (0.931 M)-barbituric acid CN- solution; CN- concentrations in the standards were

(0.117 M) solution in 0.17 M HCI. Initially, sample 50, 100, 200, 300, and 400 Jig/L. Standards were ana-

(chamber sample or blood in 0,1 N NaOH; 1.0 mL/ lyzed in triplicate and chamber samples in duplicate.

min), o-phosphoric acid (0.6 mL/min), and air (a bubble Standard curves were constructed each day by plotting

pattern of 2.5 mL/min) were mixed (in a double mixing the absorbance peak heights versusCN- concentrations.

coil) and passed thorough the distillation coil immersed The analytical response was linear over the selected

in a 155* C oil bath; this digestive distillation stage concentration range; average slope, yintercept, and corconverts complexed CN- present in the sample to HCN. relation coefficient values were 0,4731, -2,0306, and

Vapors, including HCN gas, from the coil were ad- 0.9999, respectively. Concentrations of HCN gas in the

vanced through the distillation head and, then, through chamber samples were exprcssed as ppm (v/v) at ambient

a condenser having cold (1300) water circulated in its temperature and pressure. HCN concentration in the

outer jacket; the waste (o-phosphoric acid and/or blood gas cylinder was similarly determined.

residues) from the distillation head was removed at the

4
Figure 2. Typical Chamber HCN Concentration-Exposure Time Relationships for the

5- and 35-Min Study.

During the exposure of animals to HCN gas, chamber atmosphere samples were manually collected at

selected time intervals, and HCN concentrations in the samples were determined. The gas concentration

at incapacitation was estimated by extrapolating the value of the preceding concentration to the t,. The

HCN exposure concentration was then calculated by Equation (1), as described in the text.

P 200

E 0 at

eL 150

CL.

1 00

"E so

50o

0 1' 2' 3 4

Min

E

z

L.)

4 40

AE 20

,) 0

0 10 20 30 40

Min

5
For blood CN- levels, body cavities of the killed rats distribution of 5-mmn t, values was moderate with a

were quickly opened, and blood was drawn from the spread of 3.5-min from minimum to maximum, but the

descending aorta using a 2.5-cc glass syringe and an 18- 35-man t, measurements had a wide range of 56-mmn

G needle. The collected blood samples were immediately with the 31.1 -mn mean. Blood CN- levels at incapaciinjected into stoppered glass tubes containing solid so- tation were 2.3 1Ag/mL for 184 ppm HCN and 4.2 gig/

dium heparin (143 USP units) and mixed on a mechani- mL for 64 ppm HCN (p s 0.05); the variation in the

cal rocker for 5 min. The heparinized blood samples blood CN-values was more at the 35-min t, than that at

from the test animals were diluted 1:20 with 0.1 N the 5-mmn ti. In general, variations in the 35-mmn values

NaOH in 10-mL stoppered volumetric flasks prior to ofthese parameters were about 2 times that for the 5-min

the CN- analysis. Also, 5 working standards were pre- values. In comparison to the HCN gas values, variations

pared by adding 0.5 mL aliquots of pooled blood from in the t, and blood CN- values were more; however,

untreated rats to 10-mL volumetric flasks containing variation coefficients for the t, and blood CN- values

approximately 8,0 mL of 0. 1 N NaOH. To this mixture, were not much different from each other within each set

the requisite volumes of the stock CN- solution were of studies. Except for the 5-mmn t, and 35-min HCN gas

added, and the volume was adjusted to 10 mL with the values, the 5-mmn HCN concentration, 35-mmn ti, and 5-

NaOH solution. This yielded working standards for and 35-min blood CN- measurements had normal disblood matrix containing 50, 100,200, 300, and 400 lig tribution patterns (Figure 3), as they were not statistiof CN-/L. Portions of these samples and standards were callydifferent from their correspondinggstandard normal

transferred into the AutoAnalyzer sample cups for the population forms (p > 0.05). The 35-nin HCN gas

CN" analysis in triplicate. Standard curves. prepared by measurements extended towards left from the mean.

plotting the absorbance peak heights versusCN-concen- Although the 35-min t, and CN- measurements foltrations, were linear for the concentration range. Average lowed the normal distribution patterns at p 0.05, these

valucs of slope, y-intercept, and correlation coefflricnt measurements were distributed more towards right from

were correspondingly 0.2190, 16.3554, and 0.9999, their means.

Statistics As is depicted in Figure 4, the blood CN" level

Values are presented as the mean * SD, and a difference increased as a function of exposure time for both

between means was considered significant at p s; 0.05. HCN exposure concentrations. Mean 1HCN cxpoWhere possible, data were analyzed at c - 0,05 using the sure concentrations for the 5- and 35-rnin uptake

analysis ofvarianceand Tukey's HSD multiplecompari- study were 183 * 4.4 (n - 16) and 71 :t 3.4 (n - 15)

son test for statistical pairwise differences between the ppm, respectively. Within each set of studies, HCN

groups (Wilkinson, 1989); otherwise, the significance of concentrations for the exposure intervals were not

differences between means was checked by the Student's different from each other (p > 0.05). The I-ICN gas

mtest (SigmaPlot, 1991), The normality of distribution uptakes, as represented by the blood CN" levels

of measurements was established by performing the versus exposure times, were linear; the CN- in

Kolmogorov-Smirnovone-sampletestatcacu0.05 (Miller blood did not appear to attain a steady state prior

and Miller, 1988; Wilkinson, 1989). Slope, y-intercept, to incapacitation. Mean values of slope, y-interand correlation coefficient were calculated by linear cept, and correlation coefficient for the 5-min

regression analysis. uptake study were 0.4007, 0.1666, and 0.9697,

respectively; values of these regression functions

RESUL'k S were correspondingly 0.1518, 0.1145, and 0,9920

for the 35-min uptake study. Slopes of the regresThe HCN exposure concentration for producing the 5- sion indicated that blood CN- increased at the rate

mintwas184ppm, while it was 64 ppm for the 35-min of 0.401 1tg/mL/min for 183 ppm HCN and at

t, (Table 1); coefficients of variation for these HCN 0.152 ,.Ag/mL/min for 71 ppm HCN.

concentrations were correspondingly 5.4 and 9.5%. Th,

6
Table 1. Time-to-Incapacitation (t) and Blood Cyanide (CN') Values for Rats Exposed

to Two Hydrogen Cyanide (I-ICN) Gas Concentrations.

Parameters Valuesa, b

Mean (Range) SD CV%

For 5-IfIn Study

HCN (ppm) 184 (159- 202) 10.0 5.4

tL (min) 5.1 (4.0- 7.5) 0.8 15.7

Blood CN" (pg/mL) at tj 2.3 (1.5 3.7) 0.5 21.7

For 35-MLn Study

HCN (ppm) 64 (46 - 75) 6.1 9.5

t, (min) 31.1 (14.0 - 70.0) 11.2 36.0

Blood CN" (pg/mL) at tt 4.2 (2.3 - 9.1) 1.3 31.0

aMeen values are derived from 50 rats individually exposed to HCN gas;

SD - Standard Deviation; CV - Coefficient of Variation, (SD + Mean) x 100.

bThe data from which values were calculated are listed in Tables 1 and 2 of

the Appendix.

7
Figure 3. Ditribution of HCN Exposure Concentrations, t. Values, and Blood CN"

Levels for the 5- and 35-Mm Study.

The frequency distributions for these parameters were based on the measurements derived from 50 rat

experiments (n = 50) for each of the 2 studies. The normality of distribution of measurements was

established by the Kolmogorov-Smirnov one-sample test at a = 0.05. Details are given in the text.

5-Min Study 35-Min Study

12 20 -

10 tl

U C1 i1 12

Sa L6. 4 L

2 4

0 - .0

115 15O 175 200 225 40 so 60 70 so sO

HCN (ppm) HCN (ppm)

12 12

U U

1 2 I I24 1

a. a.

4 4

0 I 0

1 2 3 4 5 6 7 a 9 0 20 40 so

tj (Min) tj (MIn)

12 - 14.-

tO 12

>, >, tO -

U " U

0 1 .1 . . . .r

.... . .. . ....... S.. II

0 I 2 3 4 -2 0 2 4 6 1

Blood CN -(Ag/rmL) Blood CN- (Ag/rL)
r a

oo

N

CmA

EL E a-

(a C¶ t

~~p I I

4 z Ok Zc4-

L'~jSt CC 10 Fn C 0

Cl (1w/Bl) ..NO P0018

LI 4Q

E9
DISCUSSION

The HCN exposure concentrations of 184 and 64 ppm pharmacological response, regardless of' ae HCN expowere determined to produce the 5- and 35-min t, in rats, sure concentration. The high CN- le t the 35-min t

respectively. The nominal variations in the HCN con- :ould be explained by the (i) possibl. lme dependent

ccntrations suggested that ýhe fluctuations in t, values binding ofCN" to non-critical sites, sequestering ofCN"

would be primarily attributed to the changes in the in erythrocytes (a CN- det.oxification mecho niim) (Vesey

individual animal response. The variations in the 35- and Wilson, 1978; McMillan and Svoboda IV, 1982),

min t, and blood CN- values were consistent with the 35- and/or enzymatic conversion ofCN- to a non-toxic form

min gas value distribution and could have been partially (Klaassen, 1990), and (ii) inability of our method to

attributtd to the increasing difficulty in the ti judgment, selectively qucrntitate critical CN-. At the low HCN

when the onset of incapacitation is less acute than at the concentration, the slower gas uptake conceivably al,,

5-mmin HCN gas concentration; Haber's rule (Packham lowed a larger fraction of CI4" to be utilized in the

and Har•ell, 1981) becomes less applicable in the con- detoxification processes, thereby retarding the critical

centration-t1 curve at a lower gas concentration and CN-" reaching a threshold level necessary for the onset of

longer t1, where the "ti" rational function, as a vertical incapacitation. Since the method employed quantitates

asymptote, is less defined (Crane, et al., 1989). There- total blood CN', the determined blood CN" ivel may

fore, a higher coefficient of vatiation would occur for a not necessarily represent a specific level for incapacita-

"longer t," in relation to ,• "shorter ti." The HCN gas tion; however, it is at least an indication of the severity of

accumulated "dose" levels derived from the C't product HCN exposure.

(C HCN exposure couicentration in ppm; t - ti in min)

were calculated to be 938 and 1990 ppmemin at 184 and The blood CN- range observed in our stvdy (1.5-9.1

64 ppm, respectively. These Cot values fall wizhin the pg/mL) is in reasonable agreement w:h the reported

reported ranges for incapacitation in humans (750-2500 ranges in humans (0.7-5.4 pg/lnL) dying from smoke

ppmemin by 200-100 ppm HCN) (Hartzell, 1989), inhalation (Baud, ct al., 1991) and in monkeys (1.2-3.0

cynomolgus monkeys (1248-1900 pprmin by 156- ;pg/mL) at incapacitation (Purser, et al., 1984) and rats

100 ppm HCN) (Purser, et al., 1984), and rats (1200- (3.1-3.7 Vg/mL) at death (Yamamoto, 1977) caused by

2700 ppm-min by 250-130 ppm HCN) (Kaplan and the HCN inhalation. Furthermore, the blood CN-level

Hartzell, 1984). Thus, the Cot values for diese species are of as high as e.4 pg/mL has been quantitated in aircraft

similar. It appears that the rat could be a reasc-ible fire victims (Mayes, 1991; Veronneau. et al., 1992).

model for predicting escape time for humans exposed to While the influence of other combustion products, e.g.,

HCN gas, a view also expressed by Kaplan and Hartzell carbon monoxide, on the overall toxicity in fire victims

(1984). cannot be ruled out, many of the blood CN- values at t,

are equal to or high er than the levels generally considered

The incr:ase in t, by decreasing the HCN exposure to be lethil in humans (Baseltand Cravey, 1989; Hartzell,

concer.tration was not cons'stent with an expected de- 1989).

crease in the 35-min t, blood CN- level; instead, there

wts a substantial increase in blood CN-. The Cot value There was a direct relationship between the HCN

appeared to be a better parameter than the HCN expo- exposure concentration and uptake, as the decrease in

sure concentration for correlating with the blood CN- the HCN concentration by a factor of 2.6 also decreased

level, since the nearly 2-fold incr.-ase in the blood CN" the blood CN- uptake rate by 2.6. Calculated uptake

was compatible with the 2-fold inccase in the Cot value, rates in (vg CN-/mL)/min/ppm HCN for both expoEven then, assuming that the measured biood CN- level sures were almost identical, i.e., 2.19 x 10-3 for 183 ppm

is directly melated to the onset of incapacitation, the HCN and 2.14 x 10- for 71 ppm HCN. Thus, this

blood CN- level should theoretically be the same at the relationship can be described by

10
REFERENCES

CoN t Baselt RC, Cravey RH (1989). Disposition of Toxic

which can be rearranged to the form Drugs and Chemicals in Man, 3rd edition, pp

224-9. Year Book Medical Publishers, Inc., Chi-

(CN')-C.toK (3) cago, IL.

Baud FJ, Barriot P, Toffis V, Riou B, Vicaut E, where CN" - blood CN- in p/mL; C - HCN exposure Lecarpentier Y, Bourdon R, Astier A, Bismuth C

concentration in ppm; t - exposure time in min; K (1991). Elevated blood cyanide concentrations in

(constant) - 2.2 x 10-3. This equation may have some victims of smoke inhalation. N, Engl. J. Med.,

utility for predicting blood CN-, HCN exposure con- 325, 1761-6.

centration, or exposure time value by knowing the values Crane CR, Sanders DC, Endecott BR, Abbott JK,

of 2 of the 3 parameters (variables). From Equation (3), Smith PW (1977). Inhalation toxicology: I. Dethe calculated blood CN- levels at incapacitation for the sign of a small-animal test system. II. Determinarats exposed to HCN in each of the 2 tj studies were 2.1 tion of the relative toxic hazards of 75 aircraft

pg/rnL for the 5-min tj and 4.4 4g/mL for the 35-min ti, cabin materials. Department of Transportation/

which corr,.sponded very closely to the experimental Federal Aviation Administration, Washington,

blood CN" mean values (Table 1). When K was derived DC. Publication No. FAA-AM-77-9. Available

from parameters obtained in the 2 t

1 studies, a mean value from National Technical Information Service,

of(2.3 * 0.5) x 10-3 was obtained (n - 100; t - ti). This Springfield, VA 22161. Order No. ADA043646/

value is exceptionally close to the K value calculated from 9GI.

theuptakestudy, suggesting that Equation (2) holds true Crane CR (1984). Inflight aircraft fires: Toxicological

up to the "exposure time* equivalent to the onset of aspects. Panel presentation at the Aerospace Mediincapacitation, as well. The equation's effectiveness is cal Association Scientific Meeting, May 7, 1984,

further supported by the apparent nonexistence ofsteady- San Diego, CA.

state blood CN- levels in uptake studies prior to ti. Crane CR, Sanders DC, Endecott BR (1989). Inhala.

Therefore, blood CN-, HCN exposure concentration, tion toxicology: IX. Times-to-incapacitation for

or t (up to t

1) can be predicted from the equation. Since rats exposed to carbon monoxide alone, to hydrothe blood CN- levels were considerably different at the gen cyanide alone, and to mixtures of carbon

5- and 35-min ti, no specific CN- level could be linked monoxide and hydrogen cyanide. Department of

to the onset of incapacitation. Transportation/Federal Aviation Administration,

Washington, DC. Publication No. DOT/FAA/

SUMMARY AND CONCLUSIONS AM-89/4. Available from National Technical Information Service, Springfield, VA 22161. Order

The HCN exposure concentradons that produced incapaci- No. ADA208195.

tation at 5 and 35 min were 184 and 64 ppm, respectively. EUROCAE (1991). Minimum operational performance

Coefficients ofvariation corresponding to these HCN con- specification for passenger protective breathing

centrations were 5.4 and 9.5%. Variations in the observed equipment. EUROCAE Document No. ED-65.

incapacitation response were 15.7% in the 5-min study and The European Organisation for Civil Aviation

36% in the 35-min study. No specificblood CN-level could Equipment Paris, France,

be linked to the onset of incapacitation. Uptake of HCN, Gad SC (1990). The toxicity of smoke and combustion

measured ar blood CN', was proportional to both HCN gases. In: Combustion Toxicology, SC Gad and

concentration and exposure time. An equation is proposed RC Anderson, eds., pp 63-80. CRC Press, Boca

that may be of use in predicting total blood CN- in the Raton, FL.

laboratory rat from HCN exposure concentration and

exposure time parameters.

11
Hartzell GE (1989). Understanding of hazards to hu- Purser DA, Grimshaw P, Berrill KR (1984). Intoxicamans. In: Advances in Combustion Toxicology, tion by cyanide in fires: A study in monkeys using

Vol. 1, GE Hartzell, ed., pp 19-37. Technomic polyacrylonitrile. Arch. Environ. Health, 39,394-

Publishing Co., Inc., Lancaster, PA. 400.

Higgins EA (1987). Summary report of the history and Sanders DC, Endecott BR, Chaturvedi AK (1991).

events pertinent to the CivilAeromedical Institute's Inhalation toxicology: XII. Comparison of toxicevaluation of providing smoke/fume protective ity rankings of six polymers by lethality and by

breathing equipment for airline passenger use, incapacitation in rats. Department of TransportaDepartment of Transportation/Federal Aviation tion/Federal Aviation Administration, WashingAdministration, Washington, DC. Publication No. ton, DC. Publication No. DOT/FAA/AM-9 1/17.

DOT/FAA/AM-87/5. Available from National Avr" .Jle from National Technical Information

Technical Information Service, Springfield, VA Serv,. Springfield, VA 22161.

22161. Order No. ADA184499. SigmaPlot (1991). SigmaPlot®: Scientific Graphing

Kaplan HL, Hartzell GE (1984). Modeling of toxico- Software. Jandel Scientific, Corte Madera, CA.

logical effects of fire gases: I. Incapacitating effects Spurgeon JC, Filipczak RA, Feher RE, Sternik SJ (1979).

of narcotic fire gases. J. Fire Sci., 2, 286-305. A procedure for electronically monitoring animal

Klaassen CD (1990). Nonmetallic environmental toxi- response parameters using the rotating wheel. J.

cants: Air pollutants, solvents and vapors, and Combustion Toxicol., 6,198-207.

pesticides. In: Goodman and Gilman's The Phar- Technicon (1974). Cyanide in Water and Wastewater

macological Basis of Therapeutics, AG Gilman, (Industrial Method No, 312-74W; March 18,

TW Rail, AS Nies, P Taylor, eds., 8th edition, pp 1974). Technicon Instruments Corporation,

1615-39. Pergamon Press, New York, NY. Tarrytown, NY.

Mayes RW (1991). The toxicological examination of Veronneau 5, Ribe JK, Sathyavagiswaran L, Lewis I,

the victims of British Air Tours Boeing 737 acci- Muto J (1992), Lessons learned from thr 1991

dent at Manchester in 1985. J. Forensic Sci., 36, USAir/SkyWest collision at LAX, presented at the

179-84. 44th Annual Meeting of the American Academy

McMillan DE, Svoboda AC IV (1982). The role of of Forensic Sciences, New Orleans, LA, February

erythrocytes in cyanide detoxification. J. 17-22, 1992.

Pharmacol. Exp. Ther., 221, 37-42. Vesey CJ, Wilson J (1978). Red cell cyanide. J. Pharm.

Miller JC, Miller JN (1988). Statiatics for Analytical Pharmac., 30, 20-6.

Chemistry, 2nd edition. Ellis Horwood Limited, Wilkinson L (1989). SYSTAT: The System for StatisChichester, West Sussex, England. tics. SYSTAT, Inc., Evanston, IL.

Packham SC, Hartzell GE (1981). Fundamentals of Yamamoto K (1977). Acute combined effects of HCN

combustion toxicology in fire hazard assessment. and CO, with special reference to a theoretical

J. Testing and Evaluation (JTEVA), 9, 341-7. consideration of acute combined effects on the

basis of the blood cyanide and COHb analyses. J.

Combustion Toxicol., 4, 69-78.

12

I1 1 W Fl1.. . .
APPENDIX

TIME-TO-INCAPACITATION (t1) VALUES AND BLOOD (CN-)

LEVELS AT INCAPACITATION FOR RATS EXPOSED

TO HYDROGEN CYANIDE (HCN) GAS

Al
Table 1.

Data for 5-Min Study.

Rat tj HCN* Blood CN" Rat qf HCN* Blood CN"

No. (min) (ppm) (pg/mL) No. (min) (ppm) (Pg/mL)

1 4.7 190 1.68 26 5.6 193 2.88

2 5,7 171 2.05 27 4.7 198 2.74

3 5.0 161 1.79 28 4.5 202 2.66

4 5.3 181 1.55 29 7.0 182 3.41

5 4.9 181 2.11 30 5.5 183 2.72

6 4.2 177 2.16 31 4.7 186 2.66

7 7.5 181 1.89 32 4.8 188 2.48

8 4.9 190 1.52 33 4.8 178 2.42

9 4.3 178 1.87 34 5.0 179 2.42

10 5.4 184 1.71 35 5.9 173 2.19

11 5.3 184 2.08 36 5.0 190 3.01

12 4.5 187 2.53 37 5,6 179 2.77

13 4.5 193 1.95 38 4.0 191 1.84

14 5.3 193 2.19 39 4.7 192 2.24

1i 4.4 181 1.52 40 4.6 197 2.61

16 4.9 171 2.29 41 4.4 202 2.42

17 5.6 159 2.11 42 4,8 190 2.80

18 6.6 163 2.98 43 4.5 188 1.87

19 6.8 165 1.95 44 5.6 188 2.13

20 6.6 168 2.19 45 4.1 193 2.56

21 4.6 188 2.88 46 4.5 180 1.89

22 4.2 185 2.64 47 5.0 184 2.37

23 7.1 181 3.01 48 4.9 200 1.52

24 5.1 188 2.24 49 4.4 183 2.11

25 5.0 190 3.70 50 4.7 180 1.52

*HCN exposure concentration, see text for definition.

A2
Table 2.

Data for 35-Min Study.

Rat t1 HCN* Blood CN" Rat t1 HCN* Blood CN"

No. (min) (ppm) (pg/mL) No. (min) (ppm) (Pg/mL)

1 40.9 54 4.50 26 43.1 64 6.29

2 22.0 52 3.11 27 41.2 66 3.26

3 28.0 51 2.81 28 53.1 60 6.59

4 35.7 46 2.83 29 22.1 66 3.21

5 34.6 53 3.16 30 30.5 67 5.76

6 34.1 48 3.13 31 38.3 64 5.46

7 26.0 60 3.24 32 26.2 66 4.90

8 56.0 57 5,63 33 24.9 65 4.17

9 23.0 65 4.53 34 38.7 65 4.40

10 21.1 65 3.79 35 21.0 66 4.45

11 33.5 61 5.00 36 14.0 69 2.38

12, 53.5 69 6.08 37 18.2 66 3.29

13 29.6 65 6.06 38 26.5 69 5.00

14 35.0 66 5.23 39 19.4 67 2.51

15 70.0 63 9.06 40 20.2 64 2.28

16 33.5 61 4.62 41 39.1 66 4.68

17 20.5 67 3.13 42 37.5 67 5.71

18 19.0 66 2.51 43 34.8 71 5.25

19 22.5 67 3.57 44 22.0 74 4.17

20 29.0 66 3.81 45 22.8 67 3.47

21 31.7 65 4.15 46 25.9 74 2.61

22 48.4 68 3.89 47 20.8 75 3.34

23 27.5 65 3.72 48 25.4 68 3.66

24 28.3 64 3.94 49 31.5 67 3.26

25 33.2 62 4.53 50 20.0 68 2.33

*HCN exposure concentration, see text for definition.

A3
Table 3.

Data for Exposure Periods Less Than t,

at Nominal 183 ppm HCN.

Rat Sxposure Time HCN Blood CN"

No. (min) (ppm) (pg/mL)

1 1.0 182 1.07

2 1.0 183 0.49

3 1.0 180 0.38

4 1.0 182 0.83

5 2.0 186 1.49

6 2.0 187 1.17

7 2.0 189 1.12

8 2.0 180 0.91

9 3.0 182 1.28

10 3.0 190 1.31

11 3.0 176 1.58

12 3.0 178 0.83

13 4.0 183 1.87

14 4.0 181 1.25

15 4.0 174 2.17

16 4.0 187 1.60

17 5.0' 176 2.74

18 5.0' 179 2.42

19 5.0* 190 3.01

20 5.0* 184 2.37

*Data for rat4 listed at the 5-min exposure time were selected from the

animals in the Appendix Table 1 for the purpose of comparison only; these

animals (No. 17, 18, 19, and 20) were incapacitated at the time of blood

removal for cN' analyses.

A4
Table 4.

Data for Exposure Periods Less Than t,

at Nominal 71 ppm HCN.

Rat Exposure Time HCN Blood CN"

No. (min) (ppm) (pg/mL)

1 2.5 70 0.14

2 2.5 67 0.77

3 2.5 77 0.34

4 5.0 75 1.70

5 5.0 69 0,64

6 5.0 74 1.17

7 10.0 72 1.52

8 10.0 68 1.32

9 10.0 74 1.52

10 15.0 66 2.03

11 15.0 67 2.81

12 15.0 72 2.76

13 25.0 69 3.54

14 25.0 71 3.62

15 25.0 67 4.37

16 35.0* 53 3.17

17 35.0* 66 5.23

18 35.0' 71 5.25

*Data for rat. listed at the 35-min exposure time were selected from the

animals in the Appendix Table 2 for the purpose of comparison only; these

animals (No. 16, 17, and 18) were incapacitated at the time of blood removal

for CN" analyses.

*U.S. GOVERUtENT PRINTING OFFICMs 1993-761-068-60066

A5