I, Transparencies. The three materials in this
category yielded a wide range of toxicity values.
One polycarbonate (No. 111) gave a t; of 3,80
min; the second acrylic (No. 109) did not in-
capacitate in 30 min (Figure 11). Material No.
111 gave the rapid production of a very high CO
level, which led to the usual short ti-tg interval.
Material No. 109 provided a surprising, although
not completely unexpected, incident in the latter
phases of the test series. After the initial tests
had confirmed that we were not going to observe
a t;<80 min for some materials, larger samples
were loaded to determine what weight would be
hecessary to obtain an observable incapacitation.
The required weight of the larger sample was
estimated on the basis of the quantity of CO and
HCN resulting from the original decomposition
of 0.75 g of material and the knowledge of the
Incapacitating doses of these gases for the rat.
When a calculated incapacitating load of No.
109, 2.25 9, was tested, the mixture of pyrolysis
gases generated was sufficiently concentrated, at
the ventilation rate of 4 Lfnin, to produce an
explosive mixture in the chamber, These gases
were ignited by a flame that originated in the
furnace tube, and the resultant explosion severely
damaged the exposure chamber. The experience
was an excellent demonstration of one of the
advantages of a chamber constructed from plexi-
glas rather than glass, and it prompted us to acid

a large blowout panel to the design of future
chambers,

J. Znsulations. Materials from this end-use
category that were included in the test series
were limited to three Fiberglas insulation batts
containing various binders (No, 97 , 66, 115A)
and a single insulation batt cover materia] (No.
28) composed of aluminized PVF and nylon
(Figure 12). The range of t,’s for the batts WAS
from 8.70 min for a melamine batt (No. 27) to
greater than 80 min for a silicone-treated pheno-
lic-Fiberglas batt (No. 66). A nonsiliconed
phenolic batt (No. 115A), on the other hand,
gave at, of 12.26 min. No deaths were observed
with any of the four materials,

The Fiberglas content of these materials is
about 80 percent (by Weight); therefore, the
umount of material undergoing decomposition in

bt a <r
> < =
— as =
= © ri =

“1 $ 8

Sf $f St

| 2 3
TRANSPARENCIES

IrgurE 11.—Transparencies, Relative toxicity of eom-
bustion products as measured by animal respouse
thne, Bottom of each bar represents t;; top of bar
represents ty. Relative toxicities decrease from left
to right.

© © o>) O
mM ©} 8) nN
A A A A
1
I
30 ! 30
=z
25 S re 25
| a ;
< 5
=,
a 20 = x 20
rg o a
b— | oO Li}
> 15 uw x re E [5
< = = = or
= us b
= 10 2] 5 ro 10
= <I . wn
<—
5 no oo = S 5
Od Os = To)
+ i $e He

INSULATION

Figure 12.—Insulations, Relative toxicity of combustion

products as measured by animal response time.
Bottom of. each har represents ti; top of bar repre-
sents ty Relative toxicities decrease from left to
right,

the :
weilg
teri
Yor
tlon
20 |
wels
mos!
Car
whe
ATC
sioN

Wer

K
hotl
test
tox]
to |
14.9
cay
abo

MINUTES

Fra


Substituting Guyton’s formula for RV (for the
albino rat) :
D=[C t 2.1 (Wt)%7*] (Wt). (D5)

By simplying this equation, we can see how the
effective dose is a function of body weight:

D=2.1C & (Wt)->, (D6)

where Wt is in grams. Thus dose is inversely
related to the fourth root of body weight.

It is obvious that the equations just derived
are based on an exposure to a constant concen-
tration of the active material. The relationship
is equally valid for a changing concentration,
provided one has adequate knowledge of the
time-concentration profile over the time interval
from t=0 tot=t, or ty. The value for the integal
(or area under the curve) of the concentration
versus time curve, from zero time to the response
time, can be entered in the equation as the (C) (t)
product. One could also think of this as finding
the Ct product, dividing by t to give an average
(or effective) concentration (C) over the expo-
sure interval, and entering this as (C) in the
original equation.

Exposure of a large number of rats, whose
body weights ranged from 100 to 500 g, to various
concentrations of CO and HCN has verified that
the derived relationship is a useful one. For the
level of activity represented by the driven wheel
in our exposure chamber, we found the following
effective doses for CO and HCN for the albino
rat.

For HCN: Incapacitating dose= 0.82 mg/kg
Lethal cose = 1.95 mg/kg
Incapacitating dose=15.385 mg/kg
Lethal dose =50.538 mg/kg

These doses are expressed as the weight of
toxic material that must be inhaled per kg body
weight to produce a given effect. They may be
converted to an equivalent concentration value
(concentration of the toxic gas in the atmos-
phere), and if expressed in (volume/volume)
parts per million (ppm), they now represent the
“dose” for a given response when the (C) in the
equation is expressed in ppm (V/V). These
values for D would then be: |

For HCN: D (incap) =

For CO:

299 ppm (

D (death) = 1,834 ppm (

For CO :D (incap) =18,907 ppm (ml/g)
D (death) =45,790 ppm (

38

Now that the effective doses for either response
are known, we can demonstrate one of the very
useful features of this relationship that is lackk-
ing in the usual expressions of “X-minute ED,.”

Tf one had a literature value of a 80-min LCso
(or Loo) for a particular gas and for an animal
weight of 350 g but was interested in a 5-min
lethal concentration for 200-g animals, the litera-
ture value is of little use beyond affording one
an approximate value from which he might
speculate. Using equation (D6), however, the
response time for a rat of any weight exposed to
any concentration (within the limiting values)
can be calculated once D has been determined.

For example, the HCN concentration, main-
tained at a constant value, that would incapaci-
tate a 200-¢ rat in § min would be (from equation

(D4)) :
G, (6 min)=D (WT)/ (RY)
= (299) (200) /[5 (2.1) (200) °75]
=107.1 ppm.

The 5-min lethal concentration would be:

Ca (5 min) = (1884) (200) /[5 (2.1) (200)°7*]
=657 ppm.

The time to incapacitation for a 800-g rat ex-
posed to a CO concentration of 15,000 ppm
would be:

t; =D(Wt)/[2.1 (C) (Wt)? ]
= (18,907) (800) /[ (2.1) (15,000) (800) °-75 |
=1.84 min.

The ta for a 500-g rat, exposed to 10,000 ppm
CO, would be 10.8 min.

These four calculations indicate the increased
utility of such a relationship.

We have independently evaluated the accuracy
of the lethal cyanide dose as calculated from our
inhalation experiments. At the same time we
have confirmed our belief that the extraction of
HCN from alveolar air into blood would be es-
sentially 100 percent efficient. (This belief was
based on the known physical and chemical prop-
erties of HCN and the conditions under which
alveolar exchange takes place.)

Since the results of our inhalation experiments
yielded a calculated lethal cyanide dose for rats
of 1.95 mg/kg, we decided to give a series of rats
a graded dosage schedule of CN- by direct intra-



Table C~3 (Continued)

td

Loss Response

ti

ati
Observed Response
ti td

wa
—
49)
dn |
uw WY
YM 2
@ 5
ei

22.3
13.2
25.1
14.4

ie aS ad

NNO
aon

13.1
16.
7

22.7
13.2
23.0
13.6

TM~ AN RN

NAO IN
a4

3
4
1

3 - oa
Standard Response
ti td
12

17

8.

2

23.3
12.6
24.5
13.

~wS aN me

NNAWO
rj ~t

12.7

7 -—~
9 8.

/

27

8

2/

Om)
Or

ATS AN AA

OtonNnas
rer

rN

rim pr

ro

CP OANSO
NAO

0 |

mye

IN dt oOo

rf

rj rd

27.8

9
6

mom
rf r

22.
17

OV uw’)
Oo OO

27.8

23.4
17.2

0

32

25.5
20.0

Nn

L5
12

102
104
107
108
109

ow ri oO ©

OtONNS
0 ee re

‘Oo 90 xt a
IN tn O 1 oa a

ONT N SOW)

RH AAANM
- o rf

Lil
112
113
11l5a
116
117

= a oy

TT INO tN NO

SOA SAM a old
on es

OI GS

1

118a
123
127
130
136
142
143a
143c
144
PVF

6
9
9
2
9
9
9
9
6
Mean RSD:

30


ANIMAL EXPOSURE CHAMBER — Left Side View

<7 7

<< 254
| jes3

>| ke 07

All dimensions in centimeters

Fieurr A-8,—Animal exposure chamber, left side. .

38



to evaluate the merit of a given material relative
only to other materials that are candidates for
the same functional end-use.

In the series of materials under test, there are
10 separate “functional” categories plus an 11th
group composed of the individual components
that make up the panel composites; eg., honey-
comb cores, adhesive, fiberglass, epoxy. The
relative rank-orders of the members of each of
these 11 categories are presented in Figures 3-13.
In each case the materials are ranked according
to their standard t,’s (bottom bar) from the most
toxic on the left (shortest t;) to the least toxic
on the right (longest t,). The materials are

Material Abbreviation

identified by their code numbers (see Appendix
B) and by an abbreviated description of the
material. These abbreviations are identified in
Table 1.

A. Panels. Most of the 13 panel assemblies
consisted of an aromatic polyamide honeycomb
core covered with Fiberglas and differed from
each other mainly in the outer-most finish layer.
Consequently, one would not expect them to ex-
hibit large differences in toxicity and this was
borne out experimentally. Values for standard
t; ranged from 2.36 min (material No, 20) to
5.85 min (material No. 12) and increased at a
fairly constant rate (Figure 8).

Material Abbreviation

Number Number
1 PVF/EPX-FG/AR HC/EPX-FG 78 ARAMID
2 EPX-FG/AR HC/EPX~FG 79 PLET URETH
6 PVF/AR FIBER-PHEN 80 URETHANE
6a PVE/AR FIBER-PHEN 81 PVC
9 AL/AR HC/AL 82 WOOL:PVG 76:24
10 FG-POLYESTER 84 PVC/COTTON
12 PVF/PLST~GLASS/AR HC 85 ABS~PVC
14 PVF/AR-EPX/AR HC/EPX-FG 86 PVG
15 PVF/ AR-EPX 88 WOOL
18 PVF FILM 89 PVC/NYLON
20 PVF/EPX-FG/AR HC/EPX—-FG/PVF 92 ARAMID
24 EPX-FG/PVC/EPX-FG 93 COTTON
25 PVF/¥G-EPX/PVF 95 RAYON .
26 FG-EPX 96 WOOL: PVC 49:51
27 MELAMINE-FG 97 PVC-POLYESTER
28 ALUMINIZED PVF/NYLON 99 PVC-PMMA
32 POLYCARBONATE 100 PVC~ABS
33 WOOL/PLST/ LATEX 102 POLYETHYLENE
34 WOOL/PLST/LTX/URETH 104 PLST URETH
37 PVF/PHEN-FG/AR HC 107 ABS-PVC
38 EPX COATED PHEN-FG 108 FR~PMMA
39 EPX COATED PHEN-FG 109 PMMA
40 AR HC/PHEN-FG BATT 111 POLYCARBONATE
i EPX COATED PHED-FG 112 SILICONE
PVF 113 PVF
43 PVF/PHEN-FG/AR HC ll5a PH eee PVE
46 PVF/PVC/PHEN~FG/AR HC/EPX-~FC 116 ~ POLYCARBONATE
50 WOOL/PHEN-FG/AR HC/EPX~FG 117 POLYPHENYLENE OXIDE
52 WOOL/EPX/AL/BALSA 118a  FG-EPX/ASBESTOS
56 PVC/SS/EPX/AR-PHEN HC 123 SILICONE
60 EPX-FG 127 MODACRYLIC
61 PVF/PVC/PHEN-FG/EPX/AR HC 130 COTTON/ RAYON
66 SIL TREATED PHEN-FG 136 PVC/COTTON
67 PVC/PHEN~FG/AR HC/EPX-FG 142 WOOL:NYLON 90:10
69 PVF/PVC/PHEN-FG/AR HC 143a 9 PLET URETH )
70 WOOL: NYLON 90:10 143c + PLST URETH
URETHANE
3 SRETRANE 144 PVF/EPX-FG/AR HC/EPX-Fc

10

One n

that cor
fire situ
min tes
69, whic

tine bet
is great
min for
represer
fire situ
tated in
ing fire
populat

B. P
these n
contrib
panel t

panel ec
that th
neie hh
the las
materi
that. th
aramid
ide in |

One
depicte
drawn
t,’s. ‘]
of ai
no cor
of aw

By |
can co
basis ¢
loss—t
therm:
order

toxic,

and P

ma ¢

toxicl
acer:
place

conta

C..
rapid
or mK
Figw


MIXING BLOWER DELIVERY TUBE
(Plexiglas)

[18 |e
oem |
All dimensions in centimeters Fl 2.5 |<

FIgurE A~14.—Detail, mixing blower delivery tube.

48


FAN ASSEMBLY

Aluminum

Aluminum shroud / O05 0.7
for cooling fan

Metal hose clamp

All dimensions in centimefers

Front (Inside chamber)

Figure A-12.—Pan Assembly,

46


RECIRCULATING BLOWER ASSEMBLY

Cole Parmer

Stir- pak motor
<—_—_— /0./ ——>| Ht 4556

Teflon washer

| |<-4.5->| >] 2.5 |S

—| 27 I< Rotor molded 0,3 "
I<-4.5—>| from epoxy resin i<—— 6.5——>| Iton O-rings
I 8. 5____5| 2.8 Id.
Bottom Side

a

5 em
All dimensions in centimeters

Picure A-10.—Recirculating blower assembly.

44



.
3
iq
“A
ae

APPENDIX A
ANIMAL EXPOSURE ASSEMBLY

IL Chamber Materials and Construction.

All transparent portions of the chamber were
constructed from Plexiglas sheets. Inlet and
outlet bushings for the combustion tube and re-
circulation assembly were machined from solid
Plexiglas stock. Each was grooved to accept two
inset Viton O-rings (Arthur H. Thomas Co., No.
S0ss8—J39, 25-mm id. x 3-mm wall thickness).
Curved plastic sections for the rotor shrouds on
the mixing and recirculating blowers were fabri-
cated from flat Plexiglas stock by heating and
bending to shape. All edge and end joints on
the chamber were reinforced by drilling, thread-
ing, and countersinking three holes per side for
flathead 8-82 machine screws approxunately 2 cim
long. Plexiglas joints were then cemented with

No. 3 Plexiglas cement (Cope Plastics, Oklahoma

City, Oklahoma).

The bearing for the steel center shaft (axle)
was machined from solid Teflon to an internal
diameter matching the shaft diameter. The mix-
ing blower rotor was machined from Teflon stock
and the rotor for the recirculation blower was
east in a rubber mold from filled epoxy resin.

The combustion tube is a 2.5-cm (0.d.) Vycor
tube with a short, graded seal attachment to a
Pyrex ball joint (SJ 35/25). The remainder of
the recirculation assembly was built from stand-
ard Pyrex tubing coupled to SJ 35/25 ground,
ball-and-socket assemblies. Sampling ports were
turned and drilled from solid Plexiglas stock and
covered with red rubber serum bottle stoppers
(7mm plug diameter x 11-mm flange diameter,
Arthur: H. Thomas Company, No. 8753-D82).
Thermocouple inserts were fabricated from cop-
per-constantan wire (24 ga., 0.508-mm diameter,
No. GG-T-24, Omega Engineering Company,
Stamford, Connecticut) cemented into bored and
shortened No. 00 rubber stoppers with a clear
silicone rubber sealer (Dow Corning No. 684).

19

Sealing gaskets for the three fan/blower as-
semblies were made by squeezing a band of clear
silicone rubber sealer onto one of the mating
surfaces and allowing it to dry. A gasket for
the chamber end plate was formed with the plate
clamped lightly in place against 8-mm-thick
spacers placed in the chamber thumbscrew holes.
Silicone rubber sealer was applied to the end
plate. The silicone was prevented from adhering
to the chamber end by covering the silicone layer
with Teflon tape strips. After the gasket had
cured, the Teflon strips were removed.

Two additional thermocouple inlets was drilled
into the back plate. One was 6 cm below the
center shaft bushing; the other was 8 cm from
the side opposite the mixing blower and 38 em
below the top surface. <A third thermocouple
inlet was drilled in the chamber bottom, centered
on the cage compartment next to the end plate
(separate drawings for the back plate and bot-
tom are not shown).

The external delivery tube for the mixing
blower was constructed (for lack of available
tubing) by boring a 2.5-cm-diameter Plexiglas
rod to the proper internal diameter, then cutting
and cementing as shown in Figure A—14.

A flow-limiting orifice for the recirculating as-
sembly was cut from thin plastic to fit the im-
ternal diameter of the 85/25 ball joint. A 6-min-
diameter hole was drilled in the center of this
(isc. An orifice of this size allowed flow-rate
adjustments to be made over the desired range
of values by altering the rpm of the controllable
blower motor.

YI. System Assembly.

Assembly of the animal exposure system 1s
accomplished by placing the chamber shell on
the channel-iron frame and plugging thermo-
couple assemblies and serumn-bottle stoppers in
the appropriate outlets. A pressure relief tube


venous (1.v.) injection and compare lethal doses.
A solution of buffered NaCN was injected into
the exposed femoral vein of an ether-anesthetized
rat; his heart action was monitored by palpation
and his respiration was observed visually. Ani-
mals receiving doses of CN-, based on individual
body weights, that were from 50 percent to 90
percent of the lethal inhalation dose (1.95 mg/
kg) survived the administration, while those re-
celving 100 percent to 200 percent of the lethal
inhalation dose succumbed.

In most of the animals, we observed rather
dramatic responses immediately following the
injection. In particular, respiration was erratic
with varying periods of apnea. Cardiac activity
also became erratic at the higher doses and, in
the case of the nonsuryivors, continued long after
respiration had terminated.

(An interesting sidelight to this experiment
that illustrates the reversibility of the observed,
intermittent periods of apnea occurred with the
animal that received 90 percent of the lethal
dose. Because this animal had experienced a
prolonged period of apnea, our attending pathol-
ogist pronounced it dead when cardiac activity
could no longer be felt; so it was placed in a
plastic bag on top of the other carcasses—the
90-percent dose was the last experiment of the
day. The plastic bag was placed in a freezer
overnight, as the aninal caretaker who handled
disposal had left for the day. In the morning,
on retrieving the bag for disposal, there sat the
“90-percent animal” on top of its deceased and
frozen litter mates. Except for frostbitten (or
frozen) nose, ears, toes and tail, it seemed none
the worse for its “cyanotic” ordeal. We mention
this primarily because it may suggest that the
use of some degree of hypothermia could have
value in the treatment of near-fatal cyanide
poisoning’. )

This correspondence between the values for
lethal dose, as determined from inhalation ex-
periments and by direct iv. injection, supports
the validity of the inhalation data and verifies
that the efficiency of HCN extraction from
alveolar space into blood approaches 100 percent.

b4

Alveolar extraction efficiencies for CO are Uy.
proximately 50 percent until the blood carboxy
hemoglobin (COHb) level reaches 40-percent to
50-percent saturation. Above this COHb leva)
the extraction efficiency for CO will declin,’
However, in our treatment of the dose-respong,
relationship, we chose to define dose as the quay.
tity of the toxic agent that is inspired and ty
ignore any fractional portion that may not be
absorbed and would therefore be exhaled. th
other words, for the purpose of calculating What
we clefine as dose, we arbitrarily assume that the
extraction efficiency is 100 percent.

We have also found that dose-response rela.
tionships measured in the above fashion may be
of use in extrapolating data from one anima]
species to another, provided the minute-respira.
tory volumes are available or can be suitably
estimated. As an example, using a literature
value for the 5-min LC, for mice exposed to
CO, we have converted this concentration figure
into its corresponding 5-min lethal inhalation
close per gram of body weight by utilizing the
Guyton equation for RV and the reported value
for animal weight. This lethal dose (per gram
of mouse), calculated from mouse LG data,
agreed within 1 percent with the lethal dose (per
gram of rat) calculated from our rat experiments,
Obviously, the effective CO dose for 1 g@ of rat
tissue equals the effective CO dose for 1 g of
mouse tissue. We have found the same agreement
between the rat data from our experiments and
d-nun LC, data from the literature for vat ex-
posures to CO.

An additional observation is even more perti-
nent to the task of attempting to solve human
problems by doing research on nonhuman species.
We found that if one converted the incapacitat-
ing CO dose for rats to the equivalent dose for a
“70-kg rat,” the resultant dose agreed within 0.1
percent with the dose predicted by the Peterson
and Stewart equation? for human acquisition of
a 46.5-percent COHb saturation.*

* Assuming that human incapacitation oceurs whe
the blood COHb level reaches 46.5-percent saturation
and using Guyton’s constant for adult human (resting)
RV of 2.06 (Wt)?



INHALATION TOXICOLOGY:
I. DESIGN OF A SMALL-ANIMAL TEST SYSTEM

Il. DETERMINATION OF THE RELATIVE TOXIC HAZARDS
OF 75 AIRCRAFT CABIN MATERIALS

I. Introduction.

In the period from 1964 to 1974, more than 900
people lost their lives in transport aircraft acci-
cents that involved fire These fatalities re-
sulted from accidents of two types: (1) an
tmpact-survivable crash followed by fire, or (11)
an in-flight fire that resultecl in an accident.
However, almost half of these fatalities (48
percent) were judged attributable to the direct
effects of the fire itself. It is now recognized
that the primary cause of death in most fires is
the inhalation of incapacitating or lethal quan-
tities of toxic gases or smoke. This is true
whether the fire is in an aircraft cabin, a resi-
dential bedroom, or a high-rise commercial
building.

Firefighters and other rescue personnel were
aware of the toxicity of combustion products
long before it was established scientifically. They
observed that many unconscious victims or fa-
talities were found in areas completely untouched
by flames. Postmortem studies eventually con-
firmed that most: of these fatalities had inhaled
suflicient. quantities of carbon monoxide (CQ) to
produce a lethal level of carboxyhemoglobin
(COHb) in the blood.

The capabilities of the forensic pathologist and
analytical cheimist/toxicologist have now pro-
eressed to the point that they can show, under
favorable circumstances, that many of the vie-
tims who do suffer thermal injuries in a fire are
first incapacitated by the toxic gases they inhale.
Unable to remove themselves from the oncoming
fiamnes, they then acquire their thermal insults.
Obviously this sequence would not necessarily
apply in an accident in which a liquid-fuel-fed
fire has entered the occupied space.

The recent availability of more sophisticated
analytical techniques has allowed the further
determination that chemical compounds other
than CO may contribute significantly to the
toxicity of the combustion products of modern
nonmetallic materials,

The recognition that hydrogen cyanide (HCN)
was a combustion product of nitrogen-containing
materials prompted Civil Aeromedical Institute
(CAMI) scientists, in 1970, to look for the first
time at the HCN level in blood specimens from
victims of an aircraft accident involving a post-
crash fire. It was definttely established that
HCN was present in the blood from several vic-
tune at Jevels greater than normal.* As a con-
sequence of these findings, we undertook a
systematic study of the inhalation toxicology of
CO and HCN, using experimental laboratory
aninals, to establish some basic relationships for
these two highly toxie gases."

In a series of experiments,’*® we determined
the inhalation doses, for each gas alone and for
mixtures of the two, that would physically in-
capacitate and that which would kill the albino
rat. We also showed that within experimental
error the magnitude of each effective close was
identical, on a per-gram-of-body-weight basis,
for rats, mice, and humans; thus, we established
wu rationale for utilizing experinental annnals to
eain information concerning human inhalation
toxicology—at least for these two gases.*

+ Forty-seven fatalities resulted from the fire that
followed a erash on takeoff of a Capitol International
Airways, Lne,, DC~8 on November 27, 1070, at Anchorage,
Alaska?


Table C~2 (Continued)

Rank

Order

41
42
43
44
45
46
47
48
49
30
51
92
53
54
55
36
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71

No animal incapacitation was noted

during the 30-min observation
period for materials No, 25, 66,

Observed ts

108

112
143¢
100
107
115a
52
60
85
89
24

PVF*

136
123

109, and 118a.

Standard ty

108

112
100
143¢c
107
52
60
89
85
24
115a
PVF
136
123

Loss ty

28

Observed ty Standard ta Loss t

bette Oeteentienns aaa d a ae anata) ane! a TER ray Te

67 38 74
96 42 42
97 96 99
33 97 56
39 33 LO4
80 80 102
84 39 97
56 56 96
112 84 41
26 112 33
81 81 80
108 26 B4
42 108 81
PVF 34 34
34 PVF 108
41 Al | PVF

No animal deaths were noted during
the 30-min observation period

for materials No, 12, 24, 25, 27,
28, 52, 60, 66, 85, 86, 89, 100,
107, 109, 1l5a, 118a, 123, 136,
and 143c.


ee ee
mt e . rg rns 2 eT) es

the furnace is only about 20 percent of the loaded
weight. It is this small amount of binding ma-
terial that is responsible for the animal responses.
For material No. 27, for instance, if the melamine
alone accounts for the t; of 3.7 min and is only
20 percent of the total weight, then on an equal
weight basis, pure melamine would be about the
most toxic polymeric material we have tested.
Careful consideration should be given to this fact

when such materials are used, for although they

are light in weight they can still comprise a
significant fraction of the total weight of poly-
meric material used in aircraft.

KK. Klastomers. Two door-sealing materials,
both of which were silicone elastomers, were
tested in the series (Figure 13). From the
toxicological standpoint, material No. 123 proved
to be the better of the two, producing a t, of
14.96 min and no deaths. Material No. 112 in-
capacitated the animals in 9.16 and killed them
about + min later.

oO
nw)
A
30 30
25 25
Y 20 20
LJ
}—
+ 15 Ly) uu) [5
< o ©
[ = _J lO
slop gl
5 wl ro 5
SH Sf:
0 - O
| 2

ELASTOMERS

Fries 13.—Elastomers. Relative toxicity of combustion
products as measured by animal response time.
Bottom of each bar represents t,; top of bar repre-
sets ty Relative toxicities decrease from left to
meht.

VI. Summary and Conclusions.

We have described in some detail the concepts.
design features, construction, and testing of a
small-scale system that utilizes small laboratory
animals for evaluating the relative toxicities of
combustion products from polymers. Overall
system performance was demonstrated by testing
75 materials used in aircraft cabin interiors and

ranking them according to their relative inhala-
tion toxicities to the albino rat.

Relative rank-orders for these 75 materials
have been presented in several ways:

A. On the basis of two animal end points;
Le, relative times-to-incapacitation and times-to-
death.

B. On the basis of equal material weights
loaded in the furnace.

C. On the basis of the loss of equal weight of
material during pyrolysis.
D. On the basis of animal response times cor-

rected for differences in animal weights and
sample weights.

The significance of the various bases for these
multiple rankings has been discussed, as have the
relative merits for selecting one base over an-
other for a specific application. We feel that
use of either “loss” or “standard” response times
is equally valid provided the choice is based on
the proper recognition of what each measurement
signifies and its relationship to the weight of the
material involved. If one were primarily inter-
ested in evaluating relative performance of ma-
terials as they would be used in an installation,
the use of “standard” response times would prob-
ably be preferable. However, if one were inter-
ested in the potency of the decomposition
products, per se, one might choose to look at.
“logs” response times. For most comparisons,
the use of “standard t,” is the one preferred by
the authors.

Judging from the distribution of t;’s through-
out the 0 to 30-min exposure period, it appears
that a more uniform distribution might have re-
sulted with a fuel load slightly less than the
0.75¢/12.6 L that was selected.


Taste B-1.—Description of Aircraft Materials”

Thickness
(in)

Unit Weight
(ox /yd* )

Chemical Compoaition

PVF/Epoxy~Fiberglas/Aramid Honey-
comb /Epoxy~Fiberglas

Designation Cabin Use

Ceiling panel

Celling panel

Epoxy-Fiberglas/Aramid Honeycomb/
Epoxy-Fiberglag (No. 1 without
PVF finiah)

PYF/Aramid Fiber~Phenolic

Panel component Face for sidewall or

window reveal (upper
- gur face)

6a PVF/Aramid Fiber-Phenolic

Panel component Face for sidewall or

window reveal (lower
surlace)

Aluminum/Aramid Honeycomb /
Aluminuns

Fiberglau-Polyeater ; Cargo liner Side cargo liner

PVF/Polyester—Chopped Glaso/
Aramid Honeycomb/Polyester-
Chopped Clase

Flooring

Overhead stowage
door assembly

14

PVF /Nomex-Epoxy/Aramid Honey-

Acquatic wall panel
comb/Epoxy Fiberglas

15 PVF /Aramid=Epoxy (Acouatic Skin
for No. 14)

PVF (Clear Film)

PVF/Epoxy—Fiberglas/Aramid Honey-
comb /Epoxy~Fiberglas/PVF

Epoxy=Fiberglas/PVC/Epoxy-Fiberglas

PVF/Fiberglae-Epoxy/PVF

Panel component

Face of acoustic wall
panel

Panel component Panel finleh

ee

Flooring Floor
Cargo liner Cargo liner

Cargo liner Cargo liner
Ineulation

Insulation
32 Polycarbonate 0.054 —_ Thermoplaatic Molded part

33 Wool Pile/Polyester Backing/Latex 0.265 Flooring Carpet
Coating

Fiberglas-Epoxy

Fuselage inaulation

Aluminized PVF/Nylon Surim

Cover fer insulation
batt

Wool Pile/Polyeater Backing/Latex
Coating/Urethane Pad ‘

PVF/Phenolic-Fiberglaa Screen/ 17.2 Panel Center ceiling panel
Aramid Honeycomb filled with
Phenolic-Fiberglas Batt/Phenolic-
Fiberglas

38 Epoxy Coated Phenolic-Fiberglas 18.4 Panel component Backface of celling
(Backing for No. 37) panel

39 Epoxy Coated Phenolic-Fiberglaa 0,018 17,6 Panvl component | Adheaived used in
(Adhesive used in No, 3/) ceiling panel

rh re ST erates - nr

+ Reproduced directly from the NAT IEC report® with the permission of the author.

21


DESCRIPTION OF THE ANIMAL EXPOSURE CHAMBER
| AND ITS OPERATION


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Material
Number

29

* N = number of animals tested


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| 2 3 4
COATED FABRICS

FIGURE 7.—Coated fabrics. Relative toxteity of combus-
tion produets as measured by animal response time.
Bottom of each bar represents ti; top of bar repre-
sents ta Relative toxicities decrease from left to
right.

I’. Flooring. The range of t,’s produced by
this group of composite materials was from 4,94
min (No. 9) to 10.90 min (No. 24) (Figure 8).
For this category, as was the case for the Panel
category, one might want to look at the loss tj
values in conjunction with the standard t, values,
for some of the flooring samples also have a non-
combustible component. For example, No. 9, an
aromatic polyamide honeycomb/aluminum sand-
wich, exhibits a surprisingly short t, when one
considers that more than 50 percent of its total
weight is metallic aluminum.

In general these materials fall into two toxicity
levels, with No. 9, 88, and 34 exhibiting t, values
of about 5 min and tg values of one and one-halt
to three times the t;. Materials No. 24 and 59
have t,’s of approximately 10 min and no ob-
served deaths. Material No. 56 represents a
transition between the two groups with a t, of
7.46 min and a te almost twice the t, value. The
last two, No. 24 and 52, would appear to be

superior materials from a purely toxicological
viewpoint based on comparisons of equal weights
of finished products.

G. Thermoplastics. The thermoplastics con-
stitute most of the molded plastic panels, seat
shrouds, etc., found in an aircraft cabin interior.
On the basis of their toxicity, these materials
fall into two distinct classes and an intermediate
group. The polycarbonate materials (No, d2, 11,
116) had t,’s of about 4 min and very short
ti-tq intervals—less than. 2 min between inecapaci-
tation and death. All the PVC/ABS materials
produced t,’s of approximately 10 min and no
deaths, while the remaining materials, a poly-
phenylene oxide (No. 117) and a PVC/aerylic
(No. 99), gave intermediate animal response
times.

In our test system all the polycarbonates, as
well as the phenylene oxide, produced very high
peak CO concentrations. The small differences
observed in animal response times may reflect
differing thermal stabilities of the respective ma-
terials rather than any substantive differences in
combustion products.

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<7 = = a. = Lj
S a 1 tT oO A + 5
ot . nm Pas uD Pe
“He te Me on
0 a)

FLOORING

Figure 8.—Flooring, Relative toxicity of combustion
products as measured by animal response time.
Bottom of each bar represents t); top of bar repre-
sents ta Relative toxicities decrease from left to
right.

14.


dose of each of these gases that. would Just result
In incapacitation or death would allow us to
calculate the resultant inhalation doses and de-
termine whether or not these two gases were
solely responsible for the observed animal re-
sponse times. If they are not, then obviously at
least a third component contributed significantly
to the total toxicity of the combustion products.*

Gas analyses were accomplished with two gas
chromatographs (GC) equipped with automated
gas-sampling valves. The sample loops of these
valves were continuously purged with a gas
stream pumped from the exposure chamber via
3.2-mm Saran tubing, through the sample loops,
and back into the chamber. The pump (Fluid
Metering, Inc., Oyster Bay, NY) exposed the
gases to only ceramic, Teflon, and stainless steel
and thus minimized reactive losses. At fixed

intervals of time the contents of these sample
loops were injected into the GC’s and the result-
ant chromatograms displayed on strip chart
recorders, One GC was utilized for the deter-
mination of HON only; the other measured the
remaining gases—CO, O., and CO.. Chamber
HCN concentrations were measured every 3.8
min; CO and O, were measured at 1.9-min inter-
vals; CO, samples were collected manually in
syringes and analyzed after the experhuent was
completed.

The frequent measurement of the Oo concen-
tration in the chamber allowed us to make
manual additions of a quantity of pure O, suf-
ficient to maintain the chamber at better than 90
percent of the normal ambient partial pressure.
The GC used for cyanide analyses was a
Shimadzu model 38B-F utilizing a 2.1-m x 4-mm
glass colunn of Porapak Q and was equipped
with a rubidium sulfate thermionic detector of
our own design. Nitrogen was the carrier OAs,

The second GC was a Carle model 8000
equipped with a 8.2-mm silica gel column. fol-
lowed by a Molecular Sieve-5A column; helium
was the carrier gas. The output signal from
a thermistor detector was paralleled to a two-
channel strip chart recorder. These two channels
were operated at clifferent attennation levels; one

* A detailed account of the results of the gas aniulyses,
and the conclusions derived therefrom, will he the sub-
ject of a subsequent Office of Aviation Medicine Report.

was selectecdl to give a full-scale presentation for
the oxygen concentration in ambient air (the
nitrogen peak was allowed to go offscale) ; the
other was adjusted for a full-scale response to
the expected CO concentration in the chamber.

_ The second column in the two-channel Carle was

a 3.2-mm x 1.83-m Porapak Q column that was
used for COQ, analysis.

G. Maximum Duration of an Exposure. Tak-
ing into account the principles outlined in Sec-
tion JI,II., we selected a maximum exposure
period of 80 min, at which time the experiment
was terminated and any surviving animals were
returned to their cages and observed for a period
of 1+ cays.

It was determined experimentally that the CO,
produced in 80 min by three rats in our system
never exceeded a concentration of 5 percent
(v/v). With 30 min as a limit, one has no diffi-
culty in completing six experiments per clay.
Also, using a maximum response time of 30 min
provides six response categories, each with a -:3
min range (848, 943, 1548, 21-8, and 27+3
min); it actually provides seven categories if one
calls “no response in 80 min” an additional cate-
gory. Ideally once this maximum exposure tine
has been selected it would be achieved experi-
inentally by selecting a fuel load to be used for
all experiments that gave the best distribution
of response times over the entire range of 30
min. To insure this one would have to pretest
all materials, possibly at several weights of fuel
load. We compromised by pretesting 12. ma-
terials that we felt would span the full toxicity
range and selected a fuel load of 0.75 @ for an
enclosed volume of 12.6 liters.

IV. Test Procedure.

Lhe sequence of operations for conducting: an
exposure experiment was as follows:

Three fasted, male rats were color coded,
weighed, and placed in the rotating cage, one to
& compartnent, The preconditioned, weighed
test material was placed in a semicylindrical
glass sample boat made by cutting a 600-mimx
18-mm tube along a diameter. The material was
positioned in the boat so that it would be in the

middle of the hot zone when placed in the pre-
heated furnace.

fo
Sl

th
a

b]
Se
in
cli

n
p
SI
v
rk
t!


Material No.

84
85
86
88
89
92
93
95
96
97
99
100
102
104
107
108
109
Lil
112
113
lida
116
117
118a
123
127
130
136
142
143a
143c
144
PVF

Table C~l1 (continued)

Observed Standard Loss
ts CG ts Ca C. ty
9.73 17.52 7.47 13.43 6.91 12.46
14.22 -—+— 10.79  ---- 9.97 ~———
7.10 te 5.50 ~--~ 4.03 ~~~
2/0 5.62 2.00 4.17 1.75 (3.63
14.29 + 10.70 -~-- 9.89 -————
2.83 5.595 2.15 4.22 2.00 3.94
3.95 5.88 3.07 4.58 2.74 4.10
5.43 7.43 4.18 5./72 3.51 4.81
5.98 13.19 4.64 10.18 4,53 9.96
9.23 13.59 6.97 10.28 6.51 9.60
7.91 11.10 6.01 8.44 5.88 8,25
12.30 -—-—— 9.41 ---- 8.49 -—~——
6.66 10.26 5.25 8.08 5.95 8.60
7.09 11.05 5.55 8.65 5.50 8.57
12.60 -—--— 9.59 ---- 8.89 -—=——
10.06 19.75 7.56 14.73 7.50 14.60
4.98 6.94 3.80 5.28 3.75 5.21
12.02 17.95 9.16 13.66 2.26 3.38
5.13 7.06 4.04 5.56 3.99 5.49
13.08 ---- 12.26 ---- 2.98 ---—
4.85 6.97 3.83 5.50 3.76 5.40
6.87 9.12 5.19 6.89 5.11 6.78
19.75 ——— 14.96 -——— 2.99 ----
1.48 3.03 1,15 2.34 1.10 2.24
3.76 5.46 2.93 4.24 2./2 3.94
18.12 -—~— 13.71 ---- 11.87 --——
2.85 6.04 2.22 4.70 2.01 4,26
6.34 9.77 5.06 7.80 5.06 7.80
12.20 -_—-—— 9.58 ———- 8.43 oe
4.28 7.02 3.19 5.26 1.77 2.92
17.17 20.33 13.02 15.42 13.19 15.61

1. Observed response times are those determined experimentally; they

have not been transformed in any way except for calculation of the

mean value of all observed times.

2. Standard response times are the observed times normalized to those

standard" 200-g animal and a "standard" fuel load of 1.000 g
rather than the weight actually used.

for a ''

3. Loss response times are the observed times normalized to those for
"standard" 200-g rat and for a loss of fuel weight of 1.000 g

a

rather than the actual weight loss.

4. A (----)entry indicates no response during the 30-min observation

period.

26


Tanue B-1—(Continued )

Thickness Unit Weight
( in} (oz/yd*) Designation Cabin Use

Chemical Composition

143a] FR Polyether Urethane 0.500 13.9 Seat cushton

een]

Seat cusliton

143c | FR Polyester Urethane Q.500 38.8

144 PVF/Epoxy-Fiberglas/Aramid 0.276
Honeyeomb/Epoxy-Fiberglas

Wall panel

ABBREVIATIONS

ARS - Acrcylonitrile/Butadiene/Styrene
FR - Flame-retardant treated

PVC - Polyvinyl chloride

PVF - Polyvinyl fluoride

24



It might be appropriate at this point to clarify
a relationship between a test system and the “real
world.” In the context of an individual trapped,
even though only momentarily, in a space filled
with smoke and toxic gases’ generated by a fire,
one might feel that even a 10-min exposure to
such an environment represents an unrealistically
lengthy dwell time. Particularly if the “space”
were a burning aircraft, one might feel that the
time available for escape or successful rescue
would be only a minute or two, certainly not
10 min, As a consequence, it might seem only
logical that, in an experimental test system ce-
siened to evaluate the toxic properties of com-
bustion gases released from burning aireratt
furnishings, the duration of exposure to the
hazardous environment be limited also to only a
very few minutes in order to be consistent with
reality.

Let us examine, however, the real purpose
of the laboratory test procedure. The objective
is to measure the acute toxicity of a mixture of
pyrolysis products from Material A and compare
it to the toxicity of the products from Material
B—and C, D, ete. If one possessed an instru-
ment into which each of these gas mixtures could
be introduced, that would produce for us a
“toxicity number” such as 1000 for Material A,
910 for Material B, and 1250 for Material C,
there would be no problem. We could accept
that A is 10 percent better than B, and that C is
25 percent better than A, when equal weights of
the three were thermally decomposed. ‘There
would be no confusion or concern over the fact
that the instrument “spent” 18 seconds perform-
ing each eas mixture analysis. There would also
be no concern that the significance of the stated
relative toxicities might be meaningless because
the quantity of toxic gas mixture utilized for the
analysis would have no effect on a person if
totally inhaled—or likewise even if it were sul-
ficient to prove fatal in 80 seconds. These
parameters ave no more related to the significance
of the analytical results than was the time re-
quired for the analysis.

In the present case, possessing no such 18-sec
instrument, our instrunient-of-second-choice 1s
the albino rat. The basis for the analytical
measurement is an observable effect on integrated
biological activity; the analytical result is the

duration of the exposure, in units of time, from
initiation until the desired biological effect 1s
produced. This interval is the time it takes our
“instrument” to make an analysis of the potency
of the gas mixture. It is also the quantitative
analytical result, analagous to the “toxicity
number” output by the first instrument. Like
the 18-sec analysis time and the resultant toxicity
number from the first instrument, the response
time of our “mammalian instrument” has no «d-
rect relationship to either escape or survival
times in a fire. It is, however, a quantity that is
related to toxicity, and by which different gas
mixtures can be rated relative to each other, and
one whose actual magnitude can be limited more-
or-less by the proper choice of other parametric
values, to any range desired by the experimental-
ists that would satisfy the four criteria listed
initially.

I. The entire system should be a closed one to
minimize the quantity of sample material re-
quired for a given animal response time. In
contrast to a continuous flow-through system, this
approach would also allow any decomposition
products that might be produced only over a
short interval of time to exert their proper toxic
potential relative to those products that are
formed ata slower rate and over a longer period.

III. Materials.

A. Animals. The laboratory albino rat was
selected for these studies for the following
reasons:

1. Convenient size (small enough to work
with, large enough to furnish adequate blood and
other tissue specimens for pathological workup).

9, Readily available at reasonable cost.

8, Significant amount of preexisting toxico-
logical and physiological data available in the
literature.

4, The expertise of the authors in conduet-
ing experiments with this animal species.

All animals were males of Sprague-Dawley
origin and were obtained from Charles River
Breeding Laboratories, Wilmington, Massachu-
setts, They were ordered at a weight range of
100 te 120 » and were held in isolation in our
facility for 2 wk prior to use. On arrival, ap-
proximately 1 rat in 10 was sacrificed and in-
spected for pulmonary pathology that might


The FAA’s concern about the hazards asso-

three rats in separate rotating compartments, | I
ciated with aircraft fires has resulted in recula-

The minimal volume is desirable to conserve the 4

ar
tions that control the flammability characteristics quantity of sample inaterial needed for each ron, | wo
of all nonmetallic material used in the cabins of to simplify the problem of insuring rapid and | eve
transport aircraft. The first regulations ap- complete mixing of a continuously changing | wit
peared in 1946, and they have been updated atmosphere, and to facilitate the disassembly and | one
periodically through May 1979.9 Concern for thorough cleaning of the system after each run, = fst
limiting the amounts of smoke ancl toxic gases B. Any material wetted by the combustion | len
produced by burning materials resulted. in the products should be as inert toward them as would | we
Issuing’ of Notices of Proposed Rulemaking be practical considering: cost, availability, and | mn
( NPRM) in these areas also. A\s a consequence, ease of construction, | wo
the Aviation Toxicology Laboratory, CAMIT, oo 1 10
undertook such studies by modifying its research C. The heating regimen to which the sample is log
task on known mixtures of pure gases to a pro-  ®Xposecl_ should be reproducible, of sufficient | sig
gram for evaluating the toxic hazard associated magnitude to insure complete thermal degrada- J yy
with inhalation of all the airborne products pro- tion of all organic components, and of a type Tt
duced by thermal degradation of nonmetallic that would encompass heat transfer by both con- | ha
materials. duction and radiation, as does a real fire. | +e
This report describes the authors’ approach to D. The thermal degradation process should be } res

a test procedure suitable for evaluating the rela- ventilated sufficiently to maintain an aerobic |
tive toxic hazard of combustion products. It — atmosphere. | of
details the design and construction of such a E. The evolved thermal degradation products | 38
system and documents its utility by testing 7 should be immediately conducted into the aninal } BS
uircratt cabin materials and generating from the vy cee Tymatned anes cht | . } it

_ . le exposure space by the shortest. practical path to |
resultant data a relative ranking of those ma- a - a | . ;  &B-
terials based on the toxicity of their combustion nuninuze loss of volatiles by condensation. ni
products to albino rats. IY, The temperature of the animal exposure tbe
Data contained in this report are derived from chamber should never reach a value that would 1 St
one specific set. of laboratory test conditions that significantly conipromise the aninal response i 91
may not. adequately reflect conditions in a large times. th
scale, uncontrolled fire, Consequently » the re- G. Oxygen concentration in the eXpostre ‘
ported data Alone lo hot indicate which of the chamber should be maintained above 90 percent rm
tested materials would be better or worse for use ko | . ra th
as cabin furnishings. They also do not reflect of the normal ambient partial Pressure. wi
what the overall level of safety night be in a TH. The maxuynun duration of an exposure th
cabin constructed of such materials. The study should be: (i) so selected that the metabolic in
cloes show, however, that for whatever conditions production of carbon clioxide by three suLVvivIng be
one might choose to accomplish the thermal wumals would not result in a concentration re
degradation of a selection of materials, the rela- greater than 5 percent; (ii) sufliciently short that tl
tive toxicities, for the rat, of their thermal de- any metabolic detoxification of a toxic species fu]
composition pre ducts can be easily and PEpro- would decrease its potential effect by a neelicible CC
ducibly quantified by the use of such a test peey aoa aye fi
system. percentage, (111) short enough to allow a mini- p
mun of six experiments per day per test system, oO.
If. System Design and Construction. and (iv) long enough, considering the precision

The following concepts were viven primary with which animal response times could be repli-

consideration in the design of the combustion / cated, to give a minimum of five theoretically il
exposure system: non-overlapping response time ranges (for ex- t]
A, The total volume should be kept to the ainple, 8 min+2 and 12 min-+9 would be two n
minim commensurate with containment of unique ranges of 6 to 10 min and 10 to 14 min). b



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A A A
30 : 30
oS
25 sz 25
Lo ©
Oeot w # & &
Lu GG <2 + 4Y 20
ik S$ FS & EF «
> 15 a pe =< ny = wn =) 15
Z 2 § & £ 2F 8 g| &
> ~ ~ ; ~ ~ a.
= [0 4 = S 5 re) > oo o> lO
> a. oO a. a] oO < oO
. .- - J vn ; <<
St osr SI el 2 ¢ 8 & & 5
oH: of “He * nn ma me md
0 O
| 2 3 4 5 6 ¢ 8
THERMOPLASTICS

Figure 9,—Thermoplastics. Relative toxicity of combustion products as measured by animal response time. Bot-

tom of cach bar represents ti; top of bar represents tu. Relative toxicities decrease from left to right.

TH. Cargo Liners. Materials in this category
consisted of Fiberglas-reinforced plastic sheets
containing variable quantities of nonflammable
material (Figure 10). In general, the observecl
t,’s were related to the quantity of noncombus-

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nN nm) mM
| A A A
| |
40 ) 30
25 > 25
Oo
~ a
Lu Lit — ao
}— on 2 <t
> 15 > Ww > |5
10 . ! ~ | |
= o of © § & °
u. Le uw O. _
- w 7 <a
9 S| Te) Oo io co 5
— aN) tO a =
Ht: th ais He H:

| 2 3 4 <)
CARGO LINERS

Figure 10—Careo liners, Relative toxicity of combus-
tion products as measured by animal response tine.
Bottom of each bar represents ti; top of bar repre-
sents tr. Relative toxicities decrease from left to
right.

tible material in each sample; 1.e., the larger the
fraction of thermally stable component, the
longer the t;.

Materials that produced animal incapacitation
within the 30-min observation period were a
Fiberglas/polyester (No. 10) and two Fiberglas/
epoxy sheets (No. 26, 60). Their respective ty’s
were 3.99, 7.68, and 10.88 min. Two materials
neither incapacitated nor killed the animals: No.
25, © PVF-coated Fiberglas/epoxy and an as-
bestos-impregnated Fiberglas/epoxy (No. 118A).
The animal survivors from tests of No. 118A
were observed for 8 days posttest and were then
sacrificed. No obvious ill effects of the potential
asbestos exposure were noted during the 8 days,
and no gross or microscopic pathology attribut-
able to asbestos was found on postmortem exam-
ination.”

* All premortem and postmortem pathology conducted
on the animals involved in this entire study was aeccom-
plished by William RK, Wirkham, Ph.D. M.D., Chief,
athology Research Unit, Aviation Toxicology Labora-
tory, Civil Aeromedical Tnstitute, The pathology results
will he published as a separate Office of Aviation Medi-
cine Report.


ve

)Tk

fl
n
d
f

ic

Sina Sir

D. Haposure Chamber. The animal exposure
and testing chamber incorporated those consid-
erations outlined earlier. It is shown clagram-
matically in Figure 1 and described in detail in
Appendix A. Basically, it is a Plexiglas box
containing a three-compartment motor-driven
f exercise wheel and two fans that accomplish
rapid mixing of the chamber atmosphere. One-
: inch-diameter openings at diagonal corners of
one face serve as ports for connecting the expo-
sure and combustion systems with a conduit for
continuous recirculation between the two.

Bee Bt rR rs i ET

SAMPLE LINE

OXYGEN

BLOWER

<q

RECIRCULATION

THERMO -

COUPLE
RECORDER

Ficurn 1,—Diagrammatic representation of overall com-
bustion-exposure-analytical system.

Numerous small openings with silicone rubber
plugs or septa provide for insertion of thermo-
couples, withdrawal of atmospheric samples, or
introduction of gases from the exterior.

The total volume of the final system is 12.6 L;
this ineludes the volune of the chamber, connect-
ing 2.54-cm (1-in) concluits, and the combustion
tubes minus the volumes of all interior solids.
The final figure was arrived at by dilution ratios
for known volumes of propane that were injected
into the closed system, allowed to mix to equilib-
vitun, and then analyzed by gas chromatography.

E. Ventilation System. A continuous recir-
culation of gases between the exposure-combus-
tion systems served to maintain an oxygenated
atmosphere in the zone of active thermal decom-
position, move the decomposition products out of
the furnace and into the exposure chamber, and
dilute and cool these products below their flan
mable concentrations and flash points.

Experimental investigation of the effects of
varying the ventilation rate showed the accept-
able limits to be 4 and 7 L/min (pm). Below
4 Lpm the oxygen in the combustion zone was
depleted significantly and the hot, concentrated
gases tended to ignite and/or explode as they
left the furnace and mixed with the oxygen dif-
fusing back from the chamber. Above 7 Lpm
the rate of heat transfer resulted in a chamber
temperature of 40° C in 10 min, which was con-
sidered excessive.

Wre believe a ventilation rate of 6 Lpm is idea!
(in our system) ; however, the tests reported here
were accomplished with a flow of 4 Lpm. This
slight compromise was desirable in order that
related tests being done at NAFIEC would cor-
relate with ours, for they found it was impossible
to accommodate a flow greater than 4 Lpm
through their analytical samplers.”

The controlled ventilation was accomplished in
our system with a variable speed blower (SCR-
controlled) and a small-diameter orifice mounted
inline and downstream from the blower. For

details see Appendix A.

F. Gas Analysis System. We felt it was de-
sirable to evaluate the concentration-time course
of certain combustion products and of oxygen
during each experiment. Therefore, an analyti-
cal capability was included in the test system
that allowed the periodic measurement of cham-
ber concentrations of CO, HCN, oxygen (Oz),
and carbon dioxide (COx,).

Information concerning the concentrations of
CO and HCN was considered important for two
reasons: (i) Many investigators feel that these
two gases are the most important of the combus-
tion products from a toxic hazard standpoint ;

(ii) Our previous determination of the inhalation

*Mhyey ultimately reduced the ventilation rate even
further, and their data® were collected at 2 Lpm.


of 2-mm id. polyethylene is fitted into a top
corner with the distal end extending mto the
intake of the overhead fume hood. The recir-
culating and mixing blowers (top) and the mix-
ing fan (side) are attached with serews and
tightened until gaskets just form a gas-tight seal
(usually finger tight).

The steel drive shaft is inserted through the
center of the cage and locked into position by
tightening the two set screws, The cage contain-
ing the animals is placed in the chamber and the
axle is rotated until the set screw on the motor
shaft engages the slot on the cage assembly shaft.
The motor shaft set screw is tightened. A short
length of coiled spring is fitted over the opposite
end of the axle to hold the cage assembly against
the rear Teflon bushing when the cover is in
place. The glass deflector plate is fitted into its
holder, the chamber cover bushing is fitted over
the cage axle, and the thumbscrews are hand
tightened until a seal is effected.

20

The furnace with the combustion tube in place
is moved toward the chamber assembly between
its aluminum guides until it comes to a stop
against a set screw in one of the guides. The
combustion tube is then inserted through the
chamber cover. The stem of a female 35/25
bal-joint unit is inserted into the outlet of the
recirculating blower, the flow-limiting orifice is
fitted onto the end of the extension tube ball
with a small amount of silicone grease, anc the
joints are clamped together. The U-tube and
thermocouple holder are then clamped into Place
to provide a continuous recirculation system,
The cage motor, temperature recorder, recirculat-
ing and mixing blowers, and fan are each plugged
into # separate outlet on the outlet strip so that
individual switches allow separate component
testing and a single master switch provides for
sunultaneous activation at the beginning of an
actual test.

wjatiny saat ace asa: in Ris

rhatiewt



TECHNICAL REPORT STANDARD TITLE PAGE

. Report No. 2. Government Accession No,

3. Recipient's Catalog No.

| FAA-AM-77~9
| 4, Title and Subtitle
INHALATION TOXICOLOGY: I. DESIGN OF A SMALL-ANIMAL

TEST SYSTEM; II. DETERMINATION OF THE RELATIVE TOXIC g—poxosminyOcconrenow Code
HAZARDS OF 75 AIRCRAFT CABIN MATERIALS

7, Authors) Charles R. Crane, Ph.D.; Donald C. Sanders,
M.S.; Boyd R. Endecott, B.S.; John K. Abbott, B.A.:
and Paul W. Smith, Ph.D.

r ©) Performing Organization Name and Address

FAA Civil Aeromedical Institute
P.O. Box 25082

Oklahoma City, Oklahoma 73125

5. Report Date

8. Performing Organization Report No.

10, Wark Unit No..

11. Contract or Grant No.

13. Type of Report and Period Covered

OAM Report
October 1974 to

12. Sponsoring Agency Name and Addres«

Office of Aviation Medicine
Federal Aviation Administration

September 1976
800 Independence Avenue, S.W.
Washington, D.C. 20591

| 14. Sponsoring Agency Code
15. Supplementary Notes

This research was conducted under Office of Aviation Medicine Task AM-A—76-—TOX-29

at the request of, and with support from, Systems Research and Development Service,

ARD-500-75-1.

16. Abstract
In an effort to further the cause of increased safety for those who ride in
commercial aircraft, this paper presents a detailed description of the genesis
of a small-scale, laboratory test system that utilizes small animals to evaluate
the relative toxic hazard of combustion products generated by the thermal
decomposition of nonmetallic materials. It includes: a discussion of the concepts
that led to the design; detailed instructions for fabricating the system;
operating parameters and instructions for conducting a test; an evaluation of the
system's performance as determined by the testing of 75 aircraft cabin materials;
the utilization of animal response time as a basis for expressing relative toxicity;
and a discussion of the derivation of an "inhalation dose” concept that promises

to be more useful than "lethal concentrations."

17, Key Words

Tnhalation Toxicology; 18, Distribution Statement

Combustion Toxicology; Pyrolysis Productsy Document is available to the public
Time-to-incapacitation; Time~to-death; through the National Technical
Cyanide Toxicity; Aircraft Cabin | Information Service, Springfield,
Materials; Relative Toxic Hazard; Animal Virginia 22151

Exposure System; Effective Inhalation Dose
19. Security Classif. (of this report) 20. Security Classif. (of this page)

21. No. of Pages

Unclassified Unclassified

Form DOT F 1700.7 (a-69)

eT Cae



ANIMAL EXPOSURE CHAMBER — Top View

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| :

Recirculating Blower

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All dimensions in centimeters

igure A-§.—Animal exposure chamber, top view,

40)



The combustion/exposure test was replicated a
minimum of three times for the first 65 materials
and therefore yielded response times based on a
minimum of nine animals. Some of those 65
were teste a fourth or fifth time (12 and 15
animals respectively) if the variation in animal
ltesponse times exceeded a standard deviation of
1 min. The final 10 materials were testecdl only
twice for a total of six animals each.

We found there were two parameters in the
experimental design that could not be quantita-
tively replicated in all experiments without in-
curring an undesirable increase in time and cost
per test. These two parameters were the body
weight of the test animals and the weight of
material placed in the furnace. Exact replication
of animal weights from test to test, especially
for animals utilized during their period of rapid
growth, would have entailed an almost daily
receipt of animals of closely specified weight
range. Weighing material specimens to within
0.5 percent of the same weight each time would
have been time consuming and would have in-
creased the risk of obtaining a nonrepresentative
aliquot from the parent Inaterial, especially

where the heterogeneous materials were con-
cernecl.

However, we have determined experimentally,
at least for the metabolic poisons such as CO,
HCN, and hydrogen sulfide (H.S), that animal
response time (t,) is a function of body weight.
{f all other conditions are held constant, t; and
tq are proportional to the fourth root of body
weight and inversely proportional to the toxic
gas concentration, (C) :

t.=k (wt) ¢ CH, (1)

We have also verified that the resulting gas con-
centration is proportional to the weight of ma-
terial that is thermally lecomposect in the furnace
and similarly that animal response times are in-
versely proportional to this sample weight
(within the limits of 0.25-1.0 & of material and
Q- to 30-min response times, and wnder the pre-
scribed test conditions).

These relationships were therefore utilized to
circumvent the problems of animal and material
sample weights that varied from experiment to
experiment. We included animals at any body
weight between 125 and 350 » and used material

samples at any weight near 0.75 eg that would
allow representative sampling. The observed Te-
sponse time was then normalized to that which
would have resulted with a 200-g animal and a
material sample weight of 1.000 g. This normal-
ized value is referred to as a “standard” response
time. (See discussion, Appendix D.)

Some of the composite materials in the test
serles contained one or more components that
were thermally stable; eg., glass fibers and
aluminum metal. These inert materials obviously
made no contribution to the final mixture of
volatile combustion products; therefore, one
might want to exclude their portion of the total
weight of a test specimen when making compari-
sons of potential toxicity on an equal-sample-
weight basis. For this reason, we also calculated
a third set of response times, normalized for a
200-g animal and a 1-g sample weight, except
that the sample weight utilized in the normaliza-
tion equation is that weight Zost during combus-
tion, not the 0.75 g loaded into the furnace,
Response times calculated in this fashion are re-
ferred to as “loss” t; and ty.

V. Discussion of Results.

Lhe observed animal responses for the 75 test
materials, as measured in the system we have
clescribed, yielded t,’s that ranged from 1.48 to
19.75 min for 71 of the materials; no incapacita-
tions were observed with the other four materials
within the prescribed 30-min exposure period,
The observed t,’s ranged from 8.03 to 24.40 min
for 56 materials; no deaths were observed in 30
min for 19 of the materials, These mean, ob-
served response times, along with the two sets of
normalized values (standard t, and loss ty),
are presented in Appendix C, Table C—1, for each
of the 75 materials and ave arranged in increas-
ing numerical order of the material identification
numbers.

The 75 materials are listed by their identifice-
tion numbers in Table C-2 in the order of short-
est to longest response times. The observed
response times are listed along with the two
corresponding: sets of normalized response tinies.
The numerical value of the response time for
any material can be found by reference to Table

C-1,

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If the material to be tested were one of the
foams or the bulky insulations a sample tube was
substituted for the sample boat. Since these are
low density materials, a 0.7-g sample would fill
the combustion tube if it were positioned along
a 150-mm length of an open boat. This would
block the flow of air. Therefore, all foam
samples were cut into 1-cm cubes and packed
into a 200-mm length of glass tube (18 mm in
diameter).

The insulation materials were packed in the
tube around a central 6-mm glass rod. When
the rod was withdrawn, just before positioning
the sample tube inside the combustion tube, the
stiffness of the material maintained the open
channel. No channel was required with the
foams because they melted down to leave an air
passage as soon as they were inserted in the 600°
C environment.

The cage was placed in the chamber and con-
nected to the drive motor, then the chamber end
plate was bolted in place. All thermocouples,
sample lines, and the overhead pressure vent line
were inserted through the proper ports. The
recirculation tubes were connected together and
the mixing fans turnecl on.

When everything was in place and the three
operator-observers were ready, the combustion
tube was opened, the sample boat was inserted,
the system was reclosed, and a master switch was
thrown. This switch turns on everything simul-
taneously, including a digital elapsed-time ind-
eator and the timing device for operating the
automated GC sampling valves.

The personnel activities during the run were:
One observed the animals and noted the times-to-
incapacitation (t,) and times-to-death (ta); one
monitored the GC presentation of chamber oxy-
een concentration, added oxygen to the chamber
when necessary, and took syringe samples of the
chamber atmosphere for CO, analysis; and one
monitored the sampling and GC system that
measured HCN, and assisted in animal observa-
tion.

The time at which visible smoke first appeared
at’ the furnace exit was recorded, as were the
time and duration of any visible flames. A
record was made of the time at which any con-
vulsions occurred in the animals, their t; and ta,

and the volume and time of all oxygen additions
to the system.

Temperatures at the eight thermocouples were
recorded automatically throughout the experl-
ment on a calibrated multipoint strip chart re-
corder. This record served as an indication of
any heat stress imposed on the animals and also
depicted the efficiency of the air-mixing fans.

The beam from an amber-lensed, high-intensity
lamp (automotive quartz-halogen fog lamp )
could be directed down through the top of the
chamber to improve visual observation of the
animals if significant quantities of smoke were
generated. Under the conditions of this test
(ie., aerobic but nonflaming combustion), most
of the materials produced little smoke, and then
it persisted for only a few minutes.

If there were survivors after 10 min, the re-
circulation blower was turned off, the conduit
tubes vemoved from the chamber, the chamber
ports stoppered, and the sample boat removed
from the furnace.

Observation of the animals continued until all
three had become incapacitated, at which time
cage rotation was stopped to simplify the task of
determining when visible respiration had ceased,
which we recorded as the ty When the last
animal had expired, the two large stopperecl
ports were opened to room air and.a third port
was connected to a vacuum source. Room air
was pulled through the chamber to flush out the

noxious and toxic gases.

The chamber was opened by removing the end
plate, and the rotating cage was removed, The
animals were immediately turned over to the
Pathology Research Unit for collection of blood
samples and pathological workup. Any surviv-
org were observed until they succumbed, or for
14 days postexposure, and were then ineluded in
the pathology study.

The exposure chamber was removed from the
system, all fans were dismounted from the walls,
and both the chamber and rotating cage were
cleaned in warm soapy water followed by an
ethanol bath. All fan blades and impellers were
also cleaned with ethanol. The parts were then
air dried and reassembled. The system was now
ready for another experiment.


_
C ©

Gearmotor, model 3MI26, 6rpm, 1/20 hp, Dayton Electric Mfg. Co.,
Chicago, Il.

Animal Exposure Chamber.

Furnace, Type 54231A, 1300 w, Lindberg, Div. of Sola Basic Industries,
Watertown, Wisc.

Electrical Outlet Strip, model IS77, Cole-Parmer Inst. Co., Chicago, Ill.
Speed Controller for Recirculating Blower, Stir-Pak solid state model

# 4556-03, Cole-Parmer Inst. Co., Chicago, III.

Furnace Temperature Controller, Type 99344, Lindberg, Div. of Sola
Basic Industries, Watertown, Wisc.

Chamber Temperature Recorder, Speedomax model H, Temperature range
29-50°C, Leeds and Northrup Co., Philadelphia, Pa.

Figure A-1l,—Animal exposure assembly.

36



“Table C-l. Mean Response Times for Each of the 75 Test Materials

Mean Responsé Time (Minutes)

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Material No. __ Observed © Standard @) Loss G3)
ty tq ty tq Cy ty

1 3.34 6.99 2.61 5.47 1.64 3.44

2 4.04 9.69 3.07. 7.38 1.76 4.23

6 6.51 9.29 5.07 7.23 1.97 2.80

6 6.68 9.37 5.22 7.31 2.20 3.08

9 6.61 9.20 4.94 6.88 2.15 2.99
10 5.09 7.89 3.99 6.20 3.60 5.59
12 7.57 ---- 5.85 ---- 3.60 en
14 3.09 6.89 2.38 5.31 1.80 4,02
15 5.09 9.05 3.89 6.94 3.74 6.66
20 3.04 5.77 2.36 4.48 1.66 3.15
24 14.68 <---- 10.90 ---- 5.37 ene
25 wane ee wae eee _--- ee
26 9.95 18.92 7.68 14.61 3.64 6.91
27 4.9] ---- 3.70 -eee 0.69 ----
28 8.71 ---- 6.56 ----- 6.24 —
32 4.94 6.71 3.70 5.02 3.61 4.90
33 7.07 15.80 5.26 11.73 4.95 11.07
34 7.35 20.43 5.53 15.35 5.13 14.26
37 5.06 7.06 3.90 5.43 2.06 2.87
38 6.27 11.96 4.79 9.15 1.44 2.75
39 7.88 16.15 6.09 12.56 2.76 5.69
40 4.31 8.14 3.22 6.08 2.51 4.74
41 11.19 24.40 8.36 18.22 4.69 10.24
42 11.40 19.91 5.82 10.16 4.71 8,24
43 4.85 7.90 3.70 6.02 2.31 3.76
46 5.59 9.61 4.18 7.17 2.37 4.04
50 6.17. 9.32 4.70 7.10 3.05 4.62
52 13.11 ---- 9.84 —---- 5.45 ----
56 10.12 17.60 7.46 12.97 4.75 8.26
60 13.63 ---- 10.33 ---- 4.37 ----
61 4.07 7.39 3.07. 5.57 2.09 3.79
66 e--- 0 ee ——-- ---— — es
67 7.33 11.97 5.58 9.15 3.34 5.48
69 6.49 8.92 4.86 6.68 2.90 3.98
70 3.66 8.27 2.72 6.16 2.36 5.36
73 5.59 8.57 4.29 6.59 4.46 6.80
74 6.61 10.61 5.04 8.08 5.10 8.15
78 3.04 8.36 2.23 6.13 2.17 5.97
79 6.35 9.70 (4.80 7.34 4.74 7.25
80 9.91 16.37 7.55 122.40 7.21 11.82
81 9.99 19.09 7.57 14.45 7.44 14.18
82 4.72 8.32 3.47 6.12 3.43 6.04

25

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ANIMAL EXPOSURE CHAMBER — Top View
Showing Blowers and Fan Installed

to \ motor

fA

Ze

INLETS

LC

Sewney peut

MIXING
BLOWER ,

| RECIRCULATING

,7 » BLOWER Re

\

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——
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3 INLET

Ficurn A-6.—Animal exposure chamber, top view, with blower and fan installed.

41

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APPENDIX C

A TABULATION OF ANIMAL RESPONSE TIMES AND THE RE-
SULTING RELATIVE TOXIC HAZARD FOR THE 75 MATERIALS,
AND THE ANALYTICAL PRECISION WITH WHICH RESPONSE
TIMES WERE MEASURED, AS REFLECTED BY THE RELATIVE
STANDARD DEVIATIONS OF THE MEAN RESPONSE TIMES.


affect its response to inhaled gases. No shipment
received during this study had to he rejected for

preexisting pathology; however, as a precaution-

ary measure, they were all maintained during
the first weels of isolation on dainking water that

contained 1 oz of sulfathiazole per each §
(approximately 1.5 ¢/L).*

After the second weelx the rats were moved
from the isolation quarters. Those to be used
during 1 day’s operation were fasted overnight
so that all would be in an equivalent metabolic
state. Just prior to use, each animal was weighed
and coded with a color mark on the head.

gal

B. Lest Materials. The subject materials that
Were evaluated in this study were supphed by
the FAA National Aviation Facilities Eixperi-
mental Center (NAFEC), Atlantic City, New
Jersey. All 75 materials had been previously
tested by them ® and were shown to possess the
flammability characteristics required by the Fed-
eval Aviation Reeulations (FAR)® for their use
as transport aireraft cabin materials. Many of
the materials may be found in use on current
models of the wide-body commercial jet fleet.

The same materials were also the subject of a
concurrent NATEC study in which each material
was to be thermally decomposed and the evolved
pyrolysis products analyzed for nine toxic G@ases,19
A complete description of the materials is in-

eluded as Appendix B,

Following veceipt of the materials from
NAFEC they were kept in resealable polyethyl-
ene bags. For the 24-hr period preceding testing
each aimaterial was conditioned in a constant
humidity chamber maintained at 50-+1 pereent
relative humidity at room feluperature (29°-940°
C). The sample specimen was then eut into
small pieces; in the case of some of the composite
materials and the more dense plastics, a small,
powered hobby saw (model 57 -2, Dremel Mee.
Co., Racine, Wise.) was used for this purpose.
A 0.75-g aliquot** of these pleces was then

* Sul-Thi-Zol, Sulfathiazole sodimn, Merek Chemical
Division, Rahway, New Jersey.

** This weight of sanple is a fuel-load/system-volume
ratio of GO mg/l, and was selected experimentally as the
quantity that seemed most likely to yield the desired
distribution among response times for most of the ma-
terials that one might want to test.

weighed to a 0.1 mg accuracy and placed in the
appropriate sample boat for insertion into the
furnace.

C. Combustion Furnace. Our choice for a heat
source, based on the considerations described
above, was the combustion tube furnace (CTE)
The CTF offers the following advantages:

+

1. A combination of radiant and concuetive

heat transfer,
2. Simple construction of total combustion
system.

d. Simple and rapid introduction of test
specimens.

4, Kase of sample quantitation,

}., Ehmination of problems with sample
melting and dripping.

6. Minimized heat transfer to the animal
chamber,

The specific CTF used in this study was a
Lindberg model 542314, with a model 59344
controller, that would accommodate tubes to a
maxunum diameter of 5.08 em (2 in). When
2.54-cm (1-in) tubes were used, they were centered
concentrically within the heaters by means of
aluminum plates mounted at each end of the
furnace.

Prior to each test the furnace was preheated
fo 625° C at the controller's sensing element (free
air temperature in the middle of the upper heat-
ing element). This resulted in a 600° C tem-
perature at the point of contact between sainple
boat and test material at the required, ventilation
vate. The furnace controller would then main-
tain this teniperature within -1° C,

The decomposition temperature of 600° C was
selected after considerable testing of various
heating regimens that ranged from 400° C to
s)0° ©; 600° C is above the final clecomposition
temperature for all materials in the study, as
determined by thermogravimetric an alysis
([GA)," and represents an environment. to
which any material in a veal fire would be sub-
jected. Also, any material that reaches a tem-
perature of 600° C would have passed through

all temperatures between ambient and 600° C. ..

eK TL ee

Seueaaeies

Sattar tice Come

ra
W
A
Cl
c:
i
U

sl
("


The system is small (12.6 L), easily constructed
by laboratory personnel, and relatively inexpen-

sive to assemble. It will accommodate from 8 to
I2 tests per day per unit, utilizing three rats per
test, with cleaning between successive tests. For
such biological end points, reproducibility of ani-
mal response times from test to test is surpris-
ingly good, as is the precision of the measurement
from animal to animal within a given test.

The simplicity of design, low cost, ease of
operation, and reproducibility of results suggest
that the significant features of this system and
its operating parameters are worthy of consid-
eration in the current search for a standard
system with which to measure the relative jn-
halation toxic hazards associated with nonmetal-
he polymeric material.

18

One must, however, bear in mind that this test
system, reproducible as it is and useful as it may
be, shares a fault common to all such systems in
use or proposed. The parameters of the thermal]
decomposition process do not necessarily repre-
sent, ancl are not presented as a representation
of, the processes that exist in a “real” fire. There-
fore, the resultant relative toxicity ranking may
not reflect the relative hazards of these or other
such materials under actual fire conditions, We
consider this to be a preliminary study with the
primary objective that of designing a suitable
system for making toxicity measurements of
gaseous environments, not reproducing actual fire
atmospheres. The described system accomplishes
that objective surprisingly well. We recommend
that additional studies be conducted to refine the
parametric values in order that they may more
adequately reflect those of significance in a fire.


APPENDIX D

DOSE-RESPONSE RELATIONSHIPS IN
INHALATION TOXICOLOGY

In earlier CAMI studies of the toxicology of
atmospheres containing CO, HCN, or mistures
of the two, we were faced with an experimental
design problem. To properly communicate the
nature of this problem and our efforts to solve it,
a short digression will be necessary.

In the classical approach to an evaluation of a
toxicological dose-response relationship, it is
axiomatic that a constant, and known, quantity
of the substance under investigation be admin-
istered reproducibly to a large number of test
animals. These animals must all be as nearly
identical as is practical. Repeated administra-
tions over a selected dosage range are then mace
to additional animals. Results of such investiga-
tions may then be expressed as the dosage re-
quired to elicit a particular animal response.
This dosage is commonly expressed as the quan-
tity of test substance administered per unit of
animal body weight. In toxicological terms this
effective dose may be referred to as a lethal dose,
an hypnotic dose, an incapacitating close, etc.

All animal experimentation involves one source
of variability with which most physical scientists
never have to contend, and that is the variability
in response from one biological individual to the
next, even when presented with identical stimuli.
The existence of such a variability therefore re-
quires that each experimental dosage be aclmin-
istered to a sufficiently large population of
otherwise identical subjects to attain a statistic-
ally reliable response. In classical toxicology this
led to the expression of “effective dose’’ in terns
such as EDs., which signifies a dose sufficient to
elicit the measured response in exactly 50 percent
of the test animals. Obviously other homologous
terms are in common usage; examples are: LD,;
{(Isthal dose for 25 percent of the test popula-
tion), EDoo, LDi, etc.

31

In addition, the biological response may vary
both qualitatively and quantitatively according
to the route of administration of a given dose.
Therefore, if one is to aclequately describe a
toxicological dose-response relationship, the route
of administration must also be specified; ¢.g.,
oral LD,o, dermal ED;;. These dose-response
relationships are quite straightforward and logi-
cal and present little difficulty for the experi-
mentalist in properly designing and executing
most toxicological investigations; that is, unless
the route of administration is to be by way of
inhalation.

In the case of a gaseous agent, how does one
quantitate the dose received by each animal? In
these instances, the common approach (histori-
cally) has been to express the concentration of
the substance under investigation as it exists in
the atmosphere to which the animals are exposed,
and specify one additional experimental param-
eter—the time interval over which the exposure
took place. The terms corresponding to effective
doses thus become effective concentrations, ad-
ministered for specified times. Examples would
be: lethal concentration for 50-percent mortality
in a 5-min exposure (5-min LC;o) or, similarly,
L0-min EC,s, etc. |

Now, after such a digression, we return to our
experimental problem. We were interested in
defining the dose-response relationships for the
effects of two toxic gases, CO and HCN, on two
responses of the albino rat. The responses we
chose to measure were physical incapacitation
(that is, loss of coordinated psychomotor control)
and death (operatively defined as cessation of
visible respiration for 20 seconds). We felt that
these two responses were the most appropriate
for an investigation concerned with the effect. of
combustion gases on an individual’s ability to
escape from a fire environment. |


The animal exposure chamber designed by the
authors for conducting these experiments 1n-
cluded four wheel-type cages similar to free-
running exercise wheels except that they were
driven externally at a constant speed. This
feature of the chamber was specifically designed
to allow the determination of physical incapaci-
tation. It would also control each animal’s
physical activity at a constant and reproducible
level during an experinent as well as from one
experiment to the next.

There were two aspects to the problem, and
they became obvious when we tried to expose
multiple sets of four animals to identical gas
concentrations. We found it extremely difficult
to quantitatively reproduce the HCN atmosphere
from test to test and also discovered that it was
going to be a logistic nightmare (as well as
unecononucal) to attempt through a long series
of tests to have each rat at the same weight at
the time of his exposure.

The inability to control these two factors to the
desirable degree meant that both of the elements
of dosage (namely, quantity of toxicant inhaled
and animal body weight) would have an unde-
sirable amount of statistical variation and thus
compromise the utility of these derived values.
We therefore decided to evaluate a different ap-
proach, one that would allow us to calculate the
dose administered to each animal and also cir-
cumvent the requirement for using animals at
only one weight.

The magnitude of a “dose” acquired by inhala-
tion would be dependent on the following factors:
(1) the respired alveolar volume, (ii) the con-
centration of the gas in the inspired air, (ili) the
elliciency of extraction of that gas from the
alveolar space into the blood, and (iv) animal
body weight. It seemed to us that each of these
parameters could be quantitated, either with cer-
tain assumptions or under specified conditions,

The volume of the respired alveolar air could
be approximated to the extent that Guyton’s re-
lationshipTM held for our experimental conditions,
Fle reported that the correspondence betiyeen
minute-respiratory-volume and body weight of
an albino rat was expressed by the equation:

RV (minute) =2,1 (body We) °7, (D1)

32

Body weight is in grams, the minute-respiratory.
volume (RV) is in milliliters per minute, and the
units of 2.1 are ml min“ g°%", Thus, RV could
be easily calculated. Since the gas concentration
in the enclosed atmosphere could be measured,
and the extraction efficiency was assumed to he
unity, the dose could be calculated.

If the toxicological principle of equal doses
eliciting equal responses (provided all other
pertinent parameters are held constant) were to
apply here, then animals of equal weight would
all inspire the same total quantity of the toxic
constituent before exhibiting the same response—
in our case, before becoming incapacitated or by
the time of death. Therefore the Incapacitating
dose for all animals of equal weight should be
identical, as should be the lethal dose.

If the effective dose for an animal were divided
by that animal’s body weight, we should have an
“effective dose per gram of body weight.” Fur
thermore, we hypothesized that at least for
poisons such as CO and HCN, the ED per gran
of body weight should be constant for animals
of any weight—with the possible exception of
the very young and the very old. We therefore
had a relationship that would allow us to make
exposures at any concentration to animals of
differing body weights and still collect useful
data.

The dose equation is derived in the following
manner: Quantity of air respired would be the
product of the minute-respiratory volume (RY)
and the time, in minutes, t:

Total Volume Respired Air= (RV) (t). (Da)

The total volume of toxic gas respired in time,
t, would be the product of the total volume of
respired air and the concentration (V/V) of the
gas in the air, (C); this would be a close, d, for
the whole animal:

d=C (RV) ¢ (D3)

Dose on a per gram body weight basis would be:
D=d(Wt)*=C(RV) t(Wt)=, (D4)

If this time, t, is the exposure interval required
to bring about the specified response, incapsacita-
tion or death, then the dose, D, is respectively the
incapacitating dose, D;, or the lethal dose, Dj
The corresponding times would be time-to-inea-
pacitation, t,, and time-to-death, t

de



MIXING BLOWER

ROTOR DETAIL

All dimensions In centimeters

Fieurr A-13,.—-Mixing blower with rotor.

47



Taste B-1— (Continued )

Thickness Unit ea
Chemical Composition (in) (ox/yd*) Designation Cabin Use

Aramid Honeycomb filled with 0,451 Panel component Ceiling panel core
Phenolic-Fiberglas Batt (Core
for No, 37)
4] Epoxy Coated Phenolic Fiberglas 0,038 Panel component Screen used in ceil-
(Screen used in No. 37) ing panel
PYF (Acoustic Skin for No. 0.015 Ceiling panel finish

PVF/Phenolic-Fiberglas Screen/ 0.732 Drop ceiling panel

Aramid Honeycomb/Aramid Honey-

comb filled with Phenolic-Fiber«
aie
pte

glas Batt/Phenolic-Fiberglas
Flooring

PVF/PVC/Phenolic-Fiberglasa/
Aramid Honeycomb/Epoxy-Fiberglaa

Upper sidewall panel

Wool Carpet/Phenolic-Fiberglas/
Aramid Honeycomb/Epoxy-Fiberglae

Lower sidewall panel

dame

Wool Carpet/Epoxy Adheaive/Aluminum/
Balsa Wood/Epoxy Adhesive/Alumitnum

Floor panel

rere rea

Floor pane!

PYC/Scainless Steel/Epoxy Adhesive/
Aramid-Phenolic Honeycomb/Epoxy
Adhesive/Stainless Steel

60 Epoxy~Fiberglas Cargo liner

61 PVF/PVC/Phenolic-Fiberglas/Epoxy
Adhesive/Aramid Honeycomb/ Epoxy

Adhesive /Phenolic-Fiberglas

Overhead stowage panel |

66

Silicone=Treated Phenolic-Fiber-
glas

Fuselage inaulation

PVC/Phenolic-Fiberglas/Aramid
Honeycomb/Epoxy-Fiberglaa

PVF/PVC/Phenolic-Fiberglas/Aramid

Door assembly
Honeycomb/Epaxy~Fiberglas

FR Wool (90 percent) /Nylon

Upholatery
(10 percent)

Seat pad
Seat pad

Upholstery
a

Seat cushion
Fae iin eh

taaemee

Seat cushion
oT A rl a TTS SE Snr
Upholatery
ey eS rere,
Upholatery

PYC (untreated) Fabric

82 FR Wool (76 percent) /PVE
(24 percent)

22


LIST OF FIGURES—( Continued)

Figure Page
9. Animal response times—thermoplastics ..-....-.---.---__-___ 15
10, Animal response times—cargo liners _.-_-.._.----------_-_____ 15
11, Animal response times—transparencies .......---_.-_-_._____ 16
12, Animal response times—insulation _......------------_-- 16
13, Animal response times—elastomers -_.---.-_----.--_--___-_____ 17
A-— 1, Animal exposure assembly —____- wae anne eee 36
A-— 2, Animal exposure chamber, end view —---_----_--.--__.-- 37
A- 3, Animal exposure chamber, left side _---.--...-.---_________- 38
A- 4, Animal exposure chamber, right side _-..--..--._--__________ 39
A- 5, Animal exposure chamber, top view _.-------_-_._._-___-__ | 40
A- 6. Animal exposure chamber, top view with
blower and fan installed -----_.-__-_ eee 41
A- T, Detail section, gas deflector assembly, side view -...__________- 42
A- 8. Rotating cage assembly, side view ~----_---________________ 42
A- 9, Rotating cage assembly, end view _--------------_- 43
A-10. Recirculating blower assembly, bottom and side views __._-___- fel
A-11. Recirculating blower assembly, front view _.-_._...________ 45
A-12, Fan assembly ------.--------_- ee 46
A-18, Mixing blower with rotor _--..--.-_-.-_--. 47
A-14, Detail, mixing blower delivery tube _--___-_--.__.____. 48
A-15. Recireulation assembly ~..-.-....--..-_---_--- 4.9

LIST OF TABLES

Table Page
{, Abbreviated descriptions of the 75 materials, as they appear in
Figures 3 through 18 ~~~ ee 10
B-1. Complete description of aircraft interior materials _......______ 21
C-1. Mean animal response times for all materials _.._....... 25
C-2. Toxicological rank-order for all 75 materials, as measured by
time to incapacitation -----_.-- ee OF
C-3. Summary of statistical evaluations for certain elements of raw
data and derived relationships _......-.------- 29



ANIMAL EXPOSURE CHAMBER —— Right Side View

| 26.4

Ciearance for
fan attachment
SCreWws.,

ULE

Frourn A—4,—Animal exposure chamber, right side.

3g



ANIMAL EXPOSURE CHAMBER — _ End View

Deflector
Assembly

Combustion
Tube Inlet

mae aE oS mh = Ps | i =)

All dimensions in centimeters

Ficurr A-2.—Animal exposure chamber, end view.

ot

Frotating
Cage

5 com


One material, No. 12, does exhibit a property
that could be worthy of consideration in some
fire situation; ie., no deaths occurred in the 30-
min test period. In contrast with material No.
69, which has about the same t;, the interval of
time between incapacitation and death for No, 12
is greater than 25 min compared to less than 2
min for No. 69. The longer t,-ty interval would
represent an increased survival potential in any
fire situation that allowed rescue of an incapaci-
tated individual by someone else, such as a build-
ing fire, or an aircraft fire at an airport or ina
populated area.

B. Panel Components. Results obtained with
these nine materials could indicate the relative
contribution to the total toxicity of a composite
panel that is made by each of the individual
panel components. From Figure 4 it 1s apparent
that there is very little difference between near
neighbors in the first seven materials; however,
the last two do differ both from the first seven
materials and from each other. It would appear
that the greatest toxicity is associated with the
aramid component, which is an aromatic polyam-
ide in either fiber or honeycomb form.

One must bear in mind that the relationships
depicted on the bar graph and the conclusions
drawn from them are all based on the “standard”
t,’s. These, in turn, are based on the equivalent
of a 1-@ fuel load of the finished material, and
no corrections are made for that residual portion
of a material that does not clecompose.

By substituting loss t,’s for stancard t,’s, one
can compare these same nine components on the
basis of response time per gram of sample weight
loss—essentially, this corrects for the quantity of
thermally stable Fiberglas in the sample. The
order of relative toxicities, from most to least
toxic, then becomes: 88, 6, 6A, 40, 39, 15, 41, 42,
and PVE. Three of the four Fiberglas-contain-
ing components move to positions of greater
toxicity. The most dramatic shift in toxicity
occurs with No. 15, which moves from seconcl
place down to sixth place; note that it does not
contain any Fibergilas.

C. Foams. As a class, the foams decomposed
rapidly under our test. conditions, leaving little
or no residue. Of the nine foams listed in
Trigure 5, seven yielced t,; values over a narrow

11

range (4.29-5.55 min). The remaining two ma-
terials, a urethane (No. 80) and a polyester
urethane (No. 148¢), as well as material No. 86,

a polyvinyl chloride (PVC) foam, produced no
deaths during the 80-min observation period.

D. Fabrics. Although materials in this cate-
gory represent a wide variety of chemical com-
positions, with few exceptions the t;’s were quite
short (Figure 6). A modacrylic drapery fabric,
No. 127, gave the shortest t, (1.15 min) recorded
for any of the 75 materials and the ty was less
than 3 min. Eleven of the twelve materials gave
t, values of less than 5 min and the remaining
one (No. 81, an untreated PVC upholstery fab-
ric) gave a t; of 7.57 min. :

In addition to producing relatively short t,’s,
several of these materials also killed the test ant-
mals quite soon after incapacitation. The elapsed
time between incapacitation and death was less
than 2 min for materials No. 93, 85, 127, and 180.
In our experience, a short survival time following
ineapacitation is usually associated with the
presence of supraletha! levels of CO.

BE. Coated Fabrics. All materials in this group
were fabrics that had been coated with PVC.

The shortest t; was 6.97 min for a lightweight,
flame retardant-treated polyester (No. 97) used
as a seat bottom diaphragm. The remaining
materials were heavy upholstery fabrics and
yielded t,’s of from 7.47 to 13.71 min (Figure 7).
Two of these materials appear particularly
promising from a toxicological standpoint. Ma-
terials No. 89 (PVO/nylon) and No. 186 (PVC/
cotton) yielded t;’s of 10.70 and 18.71 min re-
spectively, and neither material killed the test
animals in the 30-min observation period.

On a sample weight basis, both coated cotton
materials (No. 84 ancl 186) appeared to be less
toxic than their uncoated counterpart, material
No. 93. However, since the weight ratio of fab-
ric to coating in these materials is not known, it
is difficult to know whether the lowered toxicity
of the cotton/PVC materials is due (i) to the
substitution of a significant part of their total
weight with the less toxic PVC or (11) to changes
in the flammability and burning characteristics
of the fabric because of the PVC coating.


“S[QUIBSSB UOTB[NIALDaY—GL-Y Fano A

Ssaf{auss{{Ua? UL SUOsSUaWipP {V7

ante | aP!s puz

| "yIDY uy Huigny
ww 6| Bujoijs Aq pazyonaysuod (JO2AA JO X9JAd) JDOG UOolPSNquoyd

‘aq: z2’2 “‘a'o G2
aqn} uojysnquios JOXAA

xaikd GZ/GE aso siulof [1Dq ILIV

‘aQir's ‘aosa
jayoos gusof punos6 xaskd

49



at E

>30

30 - 30

25 25

20 20

15 1S

lo LO

MINUTES

es

pocal
me |

fom
pal

#143A: PLET URETH
#102; POLYETHYLENE
#143C; PLST URETH

#73. URETHANE
#79. PLET URETH
#74. URETHANE
#104, PLST URETH
#80; URETHANE

1 2 3 4 5 6 7 8 98
FOAMS

Fictre 5.—Foams. Relative toxicity of combustion products as measured by animal response time, Bottom of each

bar represents ty; top of bar represents ta. Relative toxicities decrease from left to right,

30

25

20

ie

MINUTES

| O-

WOOL: PVC 76:24

found

#96; WOOL: PVC 49:5I

|

#142; WOOL: NYLON 90:10
b=
#93; COTTON

#127: MODACRYLIC

#88: WOOL

#70; WOOL: NYLON 90:10
#130; COTTON/ RAYON

#92; ARAMID
#78. ARAMID

pacer]

#95: RAYON
#81. PYC

|
#Be;
ee |

| 2 3 4 5 6 7 8 9 10 II 12
FABRICS

Fraure G.—Fabries. Relative toxicity of combustion products as measured by animal response time, bottom
each bar represents t;; top of bar represents ta. Relative toxicities decrease from left to right.

18

30

25

20

IS

LO

of


re ORT ae Nene ee ATS FRAT ad

ASO ae PENRO

I.
II.
III.

IV.

VI.

Figure

1.

ot 69 pO

OO ~I a

G. Thermoplastics -

. Animal response times—fabrics

TABLE OF CONTENTS

Introduction

es ee ms Tee ever Ps meses rm sree me reer erates me eee reese Pres Aa ee ee se ey ge ey ee

System Design and Construction

eee Se ee ee

Materials ~~ -_u- ee ee ee ee ee ee
A. Animals

Oo ee ee ee ee

B. Test Materials ~-----------------------------------~-----
C. Combustion Furnace
D, Exposure Chamber
Kk. Ventilation System .--.-..-------..-------~---.---+--~----
F. Gas Analysis System

ee ee ee

tit A A i Nr I ar a tin i ee li i en ee i el

ne ec i et ath aed etaen Bt ee Bah antes Bad cad Mad

Test Procecure

Ce i i ei ee en i i i ee ee i ee el

Discussion of Results
A. Panels ______ tee

B. Panel Components
C. Foams

D. Fabries ~~ 1 eee eee eee ee en ee een
E. Coated Fabrics
I’. Flooring

a i i ee etn iam tidal i dnt i ii

i i i re Reticle Meets Meant na Tinie diated atiees Taam th ane linin Daniell ate tina’

a ie i Bite ee Ra i id ee ee ee ie

I I i i i it ir a i it ce ni ins ie ei i ed
i i Ei Eh el edi ee eta eee aie

ee ec nn i Re i ce Re ce Ee i et ri tian eel

H. Cargo Liners .-.------------------+-------------~---------
I. Transparencies
J. Insulations
IX. Elastomers

SS Ne ee ee ee el ie ani
ee ys ess sere esses: ees ese het tee SY ert re get ee fee eet ee ee ee eet “ey

ee ere rr rte ee er ee eee eee ee ret i ee et OE treet ee rt ge Pry

Summary and Conclusions -.-.---------------------------~---

Appendix A. Description and Operation of exposure Chamber
B. Description of the 75 Test Materials
C. Tabulated Test Data -..-..--------------~------

D. Discussion of the Dose-Response Relationship ~---

References

ey me mS ny mig sms sheer et ere remem ree Wh meet emg TG my Rey ee Se et Crm ei eet ee reg ee ey

LIST OF FIGURES

Diagrammatic representation of combustion-

exposure-test system ~...-.-.-~..------~---~-~~-~--~---~---+--
Animal response times for all tested materials
Animal response times—panels ~------------+--~--------+-----
Animal response times—panel components
Animal response times—foams

CN ee eel

Se eel
nh i Re aii

a eed

Animal response times—coated fabrics
Animal response times—flooring

A a eel

ee ee eo

Page

mR oo pw Fr

wt

wt

“I om Cl

10
11
Il
11
1]
14:
14:
15
16
16
17

17
19
21
25)
31
BO

ee nt en tt
tember - 7

ne a, belie eee
eek es ett


DISCUSSION OF THE BIOLOGICAL PRINCIPLES AND MATHE-
MATICAL RELATIONSHIPS PERTINENT TO THE CONCEPT OF A
DOSE-RESPONSE RELATIONSHIP IN INHALATION TOXICOL-

OGY.


DESCRIPTION OF THE 75 AIRCRAFT INTERIOR MATERIALS
AND THEIR PHYSICAL PROPERTIES


ACKNOWLEDGEMENTS

The authors wish to acknowledge the special contributions from the
following: Charles Gassaway for design and construction assistance with
many details of the exposure system; Charles Trent and IF. E. Anderson for
fabrication of plastic components ancl general machine-shop work; Earl
Folk, Peter Nelson, and Rosalie Melton, CAMI Biostatistical Unit, for advice
and assistance with a myriad of statistical and data-handling problems;
G. D. Hanneman, D.V.M., for his expertise and efficiency in securing and
caring for a continual stream of healthy experimental animals; Ted Goulden,

CAMI Librarian, for invaluable assistance in the never-ending quest for

“Just one more literature search”; and William Kirkham, Ph.D., M.D., Paula
Grape, and Lorrenza Snyder for post-exposure care and observation of sur-
viving experimental animals in addition to all postmortem procedures,



DETAIL OF DEFLECTOR ASSEMBLY |

End cover

Bottom of chamber

Ficure A-7.—Detail section, gas deflector assenibly, side view.

ROTATING CAGE (SIDE)

Cover Is polypropylene /
I< 6.4 —> i _—polyethylene 75/25,

3 strands per inch (mesh)

Slot 2mm deep |
and 4.2 cm long

Plexiglas

Allen head
spacers

locking screws (2)

All dimensions in centimeters
FIGuRE A~-8.—Rotating cage assembly, side view,

4.2,


Rank
Order

fable C~2.

Material Numbers Listed by Ranking Criteria

Observed t;

116

111
37
15
10

113
95
73
46
96
50
38

143a
79
69

74
102
6a
117

Standard t,

111
116
15
37
10
113
95
46
73
96
50
38
79
69

74
143a

117
6a
102

Loss ty

144
14

92
142
3/7
61

78

112
43
70
46
40

130
93
39
69

Lida

123
50
6/7
82
95
10
12
32

15
111
116
113

27

Observed ta

12/7
130
92
88
20
93
142
32
14
111
116

144
37
113
64
95
10
43
40
70
82
78
73
69
15
117

50
6a
46

79
143a
102
74
104
99
38

Materials Ranked in Order of Decreasing Toxic Hazard

Standard ty

142

144
1il
14
37

116
113
61
95
43
40
82

78
70
10
73
69

117
15
50
46

6a
79

143a
74
102
99
104
67

iii nn cl nn a ni nA ioe tii i ae etait

112

88
43
61
92
130
69
14
46
93

142
50
40
95
32

Lil
70

116
67

113
10
39
78
82
15

117
73
26
79

143a


Evaluation of similar extrapolations for HCN,
fom our rat data to humans, is made difficult
by the paucity of quantitative data for HCN
dose-response relationships in humans. However,
the lethal inhalation dose that we measure for
the rat does convert to a blood cyanide concen-
tration of 8.4 w@/mlL (assuming the HCN is dis-
tributed uniformly throughout the total body
water). Forensic data for human fatalities in-
dicate blood cyanide concentrations from 2 to
§ pe/mu. |

The dose-response relationships just discussed
for CO and HCN exposures have been applied
to the combustion experiments in the following
-jnanner :

If equation (D6) is rearranged to
C2=9,1(D)7 tC Wt)-?*5, (D7)
md it is recognized that the effective dose, D, 1s
aconstant (the quantity of toxic gas(es) required

to produce the observed response) with the effec-
tive concentration, C, proportional to the quan-
tity of. fuel, I’, that decomposed, C=kF, we can

see that for all experiments in which F is kept
constant :

t=IK (Wet) 0 (D8)

where K=D(2.1 kF)+. Therefore, for such ex-
periments, ¢ can be corrected from that obtained
with an experimental animal of any weight to
that ¢ which would have been obtained with a
standard animal weighing 200 g.

The variation in ¢ due to different fuel quanti-
ties, F, can be similarly corrected to that value
which would have resulted from a quantity of
fuel equal to one gram.

Transformations, or normalizations, based on
these concepts and assumptions were utilized in
converting the observed data to “standard” and
“loss” response times.

References

1, Starrett, P., E. Lopez, B. Silverman, J. Susersky,
J. Loran: Feasibility and Tradeoffs of a Transport
Fuselage Fire Management System, U.S. Department
of Transportation, Federal Aviation Administration
Technical Report No. FAA—RD-76-64, April 1976,

. National Transportation Safety Board, Aireraft Ac-
cident Report: Capitol International Airways, Ine.,
DC-8-G3FF, N4909C, Anchorage, Alaska, November 27,
1970: Report No, NTSB-AA R-72-12, File No, 1-0026,
172.

8, Smith, Paul W., Charles R. Crane, Donald C, San-
ders, John I. Abbott, and Boyd R. Iindecott: Effects
of exposure to carbon monoxide and hydrogen cya-
nide, Symposium (March 18-20, 1974, Salt Lake
Clty), Physiological and Toxicological Aspects of
Combustion Products, Committee on Fire Research,
NRG/NAS, Washington, D.C., 1976,

4, Sanders, D. G., CG. R. Crane, P. W. Smith, J. K.
Abbott, B. I. Endecott: Effects of Exposure to
Carbon Monoxide and Hydrogen Cyanide, paper pre-
sented at Aerospace Medical Association Meeting,

San Francisco, California, April 28-May 1, 1975,

5, Smith, P. W., GQ R. Grane, D. Sanders, J. Abbott,
I. Wndecott: Material Toxicity Evaluation by Direct
Animal Fxposure, Proceedings of International
Symposium on Toxicity and Physiology of Combus-
tion Produets, University of Utah, Salt Lake City,
Utah, March 22-26, 1976.

G Smith, P. W., G. R. Crane, D. C. Sanders, J. KK.
Abbott, B. R. Wndecott: FAA Studies of the Toxicity

BO

35

of Products of Combustion, Proceedings of the First
Conference and Workshop on Fire Casualties, May
98-99 1975, Edited by B. M. Halpin; published as
Applied Physies Laboratory/Johns Hopkins Report
No. APL/JHU FPP B 76-1, April 1976.

7, Spurgeon, J.: A Preliminary Comparison of Labora-
tory Methods for Assigning a Relative Toxicity
Ranking to Aircraft Interior Materials. Federal
Aviation Administration Report No, FAA-RD-%75-37,
1975.

8, Sarkos, C.: Measurement of Toxic Gases and Smoke
from Aircraft Cabin Interior Materials Using the
NBS Smoke Chamber and Colorimetric Tubes, Fed-
eval Aviation Administration Report No. FAA~RD-
76-7, 19°76.

9. Federal Aviation Regulations, Vol. III, Part 25.858,
May 1, 1972.

10. Spurgeon, J., L. Speitel, R. Fehrer: Thermal De-
composition Products of Aircraft Interior Materials,
Federal Aviation Administration Report No. FAA-
RD-77-20, April 1977.

11. Spurgeon, J.: FAA, NAFEC, personal communication.

12, Guyton, Arthur C.: Measurement of the respiratory
volumes of laboratory animals, AM. J. PHYSIOL,
150 :70-77, 1947,

13. Peterson, Jack E. and Richard D, Stewart: Human

absorption of carbon monoxide from high concentra-
tions in air, AM. IND, HYG, ASSOC. J., 833 :293-7,

1972,


b ey
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rie
,

SARIS BARE Mee? tigen a

vy
A
*
pa
*
7

i

4

a

i] V+]
wt j] kw

Taste B-1—(Continued )

Thickneas Unit Weight
Chemical Composition (in) (aoxz/yd* ) Deaignation Cabin Use
B4 Pyc/Cotton (untreated) 0.058 [26.9 Coated fabric

~ “

| 92 Aramid 0.036 1 Fabric Upholstery

Upholstery
Wool (49 percent) /PVC

0,044 13.8 Fabric Upholatery
(51 percent)

97 FR PVC-Polyester Coated fabric Seat bottom diaphragm
FR PVC~Polymethyl Methacrylate

102 FR Polyethylene (rigid) tse!
104 FR Polyester Urethane 4Q.1 Seat cushion

108 FR Polymethyl Methacrylate Scratch ehield
109 Polymethyl Methacrylate 0,260 Window, pane

: 8

Fuselage insulation

Seat side panels and
trays

Flotation cushion and
padding for seat back
and arm rest

PVC (untreated)

3
=
8

FR Cotton,

Seat shroud

Elastomer

i13 pVE/Polycarbonate/PVF 0,441 Thermoplastic

115a| Phenolic-Fiberglas

Insulation

Thermoplastic Passenger service

units and luminaires

31.4 Thermoplastic

Flight station and

ll? Polyphenylene Oxide
lavatory parts

lld¥a| Fiberglas-Epoxy/Asbeatos 0,020 28.9 Cargo liner Cargo liner
123 Silicone 0.124 116 Elastomer

127 Modacrylic 0.032 8.63 Drapery
130 Cotton/Rayon 0,040 15.0 Fabric

146 PVC /Cotton 0.057 Coated fabric Upholetery

EE ge Se

es wae

142 FR Woo! (90 percent)/Nylon
(10 percent)

Fabric Upholatery

3)


The statistical precision with which each of the
response times was measured is depicted im Table
C3, For each test material we have listed the
total number of experimental animals (N) and
the relative standard deviation of the mean (co-
efficient of variation) calculated for each of the
six response times. A majovity (65 percent) of
these relative standard deviations (RSD) fall
between 5 and 15 percent RSD, and almost 40
percent. of them are less than 10 percent RSD.*

Figure 2 is a specialized bar graph that depicts
the standard t, and standard ty for each of the 75

— ———————

* On the basis of previous work with pure gases and
of results from the burning of homogeneous polymeric
specimens, we feel that those RSD above 10 to 15 per-
cent are due primarily to lack of homogeneity in repli-
cate specimens and/or nonreproducible thermal decom-
position.

Ol
©

nN ae oO ea)
pop ft

O
TMm
A
l
. Nf;
a
Wei
F ol
— |0
2
= 8
6
4 | | | |
Tl
Shhh one he eee tie tte es
ot- aoe ie

MATERIAL

Picture 2.—Animal response times (std. tr and ta) for the
less,

Bottom of each bar represents ti; top of har represents fa.

materials, arranged in the sequence of increasing
ti. It is apparent that the series of t's represents
a near continuum of values, with no obvious or
significant breaks in the pattern; therefore, any
attempt to place into separate hazard categories
two materials that are adjacent, or possibly even
near each other, in the plot would require a most
arbitrary division.

An additional observation was that materials
within each “end use”? category, such as Toams,
panels, fabrics, thermoplastics, etc., had about
the same toxicity ranking. Therefore, an arbi-
trary division of the total group of materials
into good versus bad, acceptable versus unaccept-
able, good versus better, etc., by drawing a line
at a given t-value would likely place all the
elements of one or more end-use categories into
the unacceptable group. It seems more realistic

pe ws re) i) rm mr
A AA AAAAAAAAA AA_ 3 4
18
16
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OO ON oe TEU e naa nas oaN soe ON OOON” ZN
z = ommre epics att 0

NUMBER >

71 materials that produced incapacitation in 80 min or
Relative toxicities decrease from left to right.

Q .



ROTATING CAGE (END) |

Hieavy rubber band (3) “Steel wire hook

7 cm overlap ) a
x 0.6 cm thick Plexiglas i

disc. 20 cm diameter

mesh

I.3 cm holes cut

in all 4 plastic
ends and dividers |
20

Polypropylene/ polyethylene
75/25 plastic mesh 3

strands per inch

J |

_ 5 em
K All dimensions in centimeters |

lrcurz A-9.—Rotating cage assembly, end view.

43



RECIRCULATING BLOWER
ASSEMBLY

All dimensions in centimeters

Front

Figure A-11.—Recirculating blower assembly, front view.

45



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