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B

A1 11 02577833 ^ _ Levin Barbara C/Comparlson of ffie „ QC100 .U56 NO.86-3457 1986 V19 C.1 NBS-P Comparison of the Toxicity of the

Combustion Products From A

Fiexible Polyurethane Foam and

A Polyester Fabric Evaluated

Separately and Together By

the NBS Toxicity Test Method

and A Cone Radiant Heater

Toxicity Test Apparatus

Barbara C. Levin, Emil Braun, Joshua L. Gurman, and Maya Paabo

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Center for Fire Research

Gaithersburg, MD 20899

November 1986

Sponsored in part by;

Qf 'Consumer Product Safety Commission

‘sda, MD 20207

.1156

86-3457

1986

C. 2

NBS

RESEARCH

INFORMATION CENTER NBSIR 86-3457 Ng-scCXc^ioO

COMPARISON OF THE TOXICITY OF THE . COMBUSTION PRODUCTS FROM A

FLEXIBLE POLYURETHANE FOAM AND i

A POLYESTER FABRIC EVALUATED i, >

SEPARATELY AND TOGETHER BY

THE NBS TOXICITY TEST METHOD

AND A CONE RADIANT HEATER

TOXICITY TEST APPARATUS

Barbara C. Levin, Emil Braun, Joshua L. Gurman, and Maya Paabo

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Center for Fire Research

Gaithersburg, MD 20899

November 1986

Sponsored in part by:

The Consumer Product Safety Commission

Bethesda, MD 20207

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
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I
Table of Contents

PaEe

List of Tables iv

List of Figures v

Abstract 1

1. Introduction 2

2 . Materials and Methods 4

2.1 Materials 4

2.2 Chemical Analysis 4

2 . 3 Animals 4

2.4 Animal Exposures 5 2.5 The NBS Toxicity Test Method 6 2.6 Experimental Procedure with the NBS Toxicity Test Method .... 8

2.7 The Cone Radiant Heater Toxicity Test Apparatus 9

2.8 Experimental Procedure Using the Cone Radiant

Heater Apparatus 11

2.9 Data Reduction for the Cone Radiant Heater Test Apparatus ... 13

3. Results 15

3.1 The NBS Toxicity Test 15

3.1.1 Flexible Polyurethane Foam 15

3.1.2 Polyester 16

3.1.3 Flexible Pol)njirethane Foam and Polyester Combined ... 17

3. 1.3.1 Non-Flaming Combined Experiments 17

3. 1.3.

2

Flaming Combined Experiments 19

3.2 The Radiant Cone Heater Toxicity Test Apparatus 21

3.2.1 Flexible Polyurethane Foam 21

3.2.2 Polyester Fabric 21

3.2.3 Combined Polyurethane and Polyester Experiments 22

4. Discussion 23

5. Conclusions 33

6. Acknowledgements 36

7. References 37

Appendix A 59

iii
List of Tables

Table 1. Toxicity Results for Flexible Polyurethane #13 Using the NBS

Toxicity Test Method 39

Table 2. Toxicity results for the Polyester Fabric Using the NBS

Toxicity Test Method 40

Table 3, Toxicity Results for Flexible Polyurethane #13 plus Polyester

Using the NBS Toxicity Test Method 41

Table 4. Toxicity Results for Flexible Polyurethane #13 Using the Cone

Radiant Heater 42

Table 5. Toxicity Results for the Polyester Fabric Using the Cone

Radiant Heater 43

Table 6. Toxicity Results for Flexible Polyurethane #13 plus Polyester

Using the Cone Radiant Heater 44

Table 7. Gas Concentrations from the Thermal Decomposition of

Polyurethane Foam and Polyester Alone and in Combination

by the NBS Toxicity Test Method 45

iv
List of Figures

Page

Figure 1.

Figure 2

.

Figure 3

,

Figure 4.

Figure 5

.

Figure 6

Figure 7

.

Figure 8

Figure 9

Figure 10

.

Figure 11.

NBS Toxicity Test Method animal exposure chamber and

furnace 46

Schematic of NBS Toxicity Test Method and gas

analysis system 47

NBS Toxicity Test Method pyrolysis/combustion furnace 48

Cone radiant heater toxicity test apparatus 49

The cone radiant furnace in vertical and horizontal modes.. 50

Concentration- response curves for flexible poljmre thane

foam (NBS Toxicity Test Method) . All deaths occurred

during the 14 day post-exposure period 51

Concentration- response curves for polyester decomposed in

the non- flaming mode (NBS Toxicity Test Method) 52

Concentration- response curves for polyester decomposed

25 °C above and below its autoignition temperature

(NBS Toxicity Test Method) 53

Concentration- response curves for polyurethane alone,

polyester alone, and a mixture of polyurethane and

polyester (20 mg/i), all of which were decomposed in

the non-flaming mode at 375°C (NBS Toxicity Test Method).

Also shown is the combined theoretical concentrationresponse curve based on the pol3rurethane plus the addition

of 20 mg/i of an inert material 54

Concentration-response curves for polyester alone (flaming,

525'*C), polyurethane alone (flaming 425°C) and polyester

plus polyurethane (20 mg/£) decomposed in the flaming mode

at 525° C (NBS Toxicity Test Method) . Also shown is the

combined theoretical concentration- response curve based on polyester plus 20 mg/Jl of an inert material 55

Generation of hydrogen cyanide from polyurethane decomposed

in the flaming mode in the NBS toxicity test apparatus. In

all cases, the mass loading of polyurethane was 3.88 g

(20 mg/i) . Polyurethane decomposed alone at 425°C ( )

or at 525°C ( — , A — A); 20 mg/i polyurethane at 525°C

with polyester a 22.5 mg/

2

(A), 25 mg/

2

() , 15 mg/

2

(V),

20 mg/2 (•), 30 mg/2 (0) 56

V
List of Figures (continued)

Page

Figure 12 . CO generation from flexible polyurethane foam and

polyester decomposed alone and together. (Flaming,

525°C, NBS Toxicity Test Method) 57

Figure 13. CO generation from flexible polyurethane foam and

polyester decomposed alone and together. ( Non- flaming,

SyS^C, NBS Toxicity Test Method) 58

VI
COMPARISON OF THE TOXICITY OF THE COMBUSTION PRODUCTS FROM A FLEXIBLE

POLYURETHANE FOAM AND A POLYESTER FABRIC EVALUATED SEPARATELY

AND TOGETHER BY THE NBS TOXICITY TEST METHOD AND A

CONE RADIANT HEATER TOXICITY TEST APPARATUS^ >

Barbara C. Levin, Emil Braun, Joshua L. Gurman^ , and Maya Paabo

ABSTRACT

Representative specimens of flexible pol3rurethane foam and polyester fabric

were thermally decomposed separately and together in order to compare the

toxicity of the combustion products from the combined materials with those from

the single homogeneous materials and to compare the toxicological results

obtained with the NBS Toxicity Test Method with those using a cone radiant

heater toxicity test apparatus. Gas concentrations (GO, CO2 , O2 and HCN)

,

blood carboxyhemoglobin, and LCjq values in Fischer 344 rats were determined

for the separate and combined materials under both flaming and non- flaming

conditions. Using the NBS Toxicity Test Method, the non- flaming combined

experiments indicated that both materials contributed in an additive manner to

the concentration of the combustion products. However, under flaming

conditions, the generation of HCN is greater than that predicted from the

addition of the maximum amounts produced by the materials separately. With the cone radiant heater apparatus operated so as to generate the maximum

concentrations of combustion products in the animal exposure chamber, deaths

were observed in the combination experiments, but not in the single material

exposures. In the combined material testing with both toxicity test systems,

flaming conditions produced deaths within the 30 minute exposures; whereas,

non- flaming conditions produced deaths following the exposures. Estimated LC^q

values for the combined materials in the radiant furnace were not greatly

different from the calculated values obtained with the NBS Toxicity Test.

Key words: combustion products; inhalation; lethal concentrations; Toxicity

Test Methods; polyesters; polyurethane foams; radiant heat; toxicity;

upholstered furniture.

^ This paper is a contribution of the National Bureau of Standards and is not

subject of copyright.

^ Presented in part at the First International Symposium on Fire Safety

Science, National Bureau of Standards, Gaithersburg, MD, Oct., 1985 and the

Eighth U.S. -Japan Panel on Fire Research and Safety, Tsukuba, Japan, May, 1985.

^ NBS Research Associate, American Iron and Steel Institute

1
1. INTRODUCTION

The United States has the worst fire loss record in the industrialized

world [1]^. The fire scenario which produces the most fire deaths in the U.S.

begins with an inadvertently dropped cigarette in an upholstered chair, which

smolders for an undetermined time period (sometimes more than an hour) before

bursting into flames. Approximately 2/3^^^® of all fire deaths occur away from

the room of fire origin and many of the victims of such fires die of smoke

inhalation in or near their beds indicating little or no attempt or ability to

escape

.

Since the majority of commercially available upholstered furniture today

contains flexible polyurethane foam as a filling material and a covering fabric

which is either a cellulosic or a thermoplastic (such as polyester)

,

polyurethane and polyester were chosen for this study. Many small-scale

laboratory studies have examined the toxicity of the combustion products from

either flexible polyurethane foams [2] or polyesters [3] . There have also been

numerous large-scale room burns of chairs, multiple materials, or composite

materials which have included among others, flexible polyurethane foams and

polyesters. However, to our knowledge, there has been no systematic study

which has examined the acute inhalation toxicity of the thermal degradation

products from combinations of materials, first as separate materials and then

together as is reported here.

^ Numbers in brackets refer to the literature references listed at the end of

this report.

2
Experiments by Alarie et al. were somewhat similar in concept in that they

compared the toxicity of individual materials (determined in small-scale tests)

with the toxicity of multiple combined materials (determined in large-scale

chair burns) [4]

.

However, the objective of their study was to compare the

toxicity of the combined major components of the chairs (flexible polyurethane

foam, polyester, and cotton fiber) with their individual toxicities in smallscale tests. They did not study the toxicity of the combined components in the

small-scale tests.

This study was designed to examine: (a) the toxicological effects from the

combustion products of a flexible polyurethane foam and a polyester fabric

(alone and in combination) in order to determine the contribution of each

material to the overall toxicity of the mixture and (b) to compare the

toxicological results obtained under the conditions of the NBS Toxicity Test

Method [5] with those from a radiant cone heater toxicity test apparatus [6]

.

Three separate aspects of testing composite materials were considered: (1) Are

the results for the composite specimen derivable from mass -proportioning the

component results or does some unexpected toxicological interaction occur? (2)

Would the yields of the major toxicants be affected? (3) Are the observed

lethalities predictable based on the individual or combined concentrations of

the primary toxic gases, namely, carbon monoxide (CO), carbon dioxide (CO2 ),

and hydrogen cyanide (HCN)?

3
2. MATERIALS AND METHODS

2.1 Materials

The materials studied were a polyester upholstery fabric (100% polyester,

scoured and dyed dark blue) and a flexible polyurethane foam, two common

components of commercially available upholstered chairs. Both materials were

obtained from the Consumer Product Safety Commission, Washington, D.C. 20207

and were generically classified, i.e., the specific chemical formulations were

unknown. The results of a previous toxicological study on the same polyurethane foam, designated CPSC #13, have been published [7].

2.2 Chemical Analysis

Carbon monoxide and CO2 were measured continuously by non- dispersive infrared

spectroscopy. Oxygen (O2 ) concentrations were measured continuously by a

galvanic cell or a paramagnetic analyzer. The CO, CO2 , and O2 data were

recorded by an on-line computer controlled data collection system every 15

seconds. Hydrogen cyanide was sampled with a gas-tight syringe approximately

every three minutes and analyzed with a gas chromatograph equipped with a

thermionic detector [8].

2 .

3

Animals

The animals used for these experiments were Fischer 344 male rats weighing 200

300 grams. They were obtained from the Harlan Sprague -Dawley Company

4
(Walkersville , Maryland)^ or laconic Farms (Germantown, New York) and were

allowed to acclimate to our laboratory conditions for at least 10 days prior to

experimentation. Animal care and maintenance were performed in accordance with

the procedures outlined in the National Institutes of Health's "Guide for the

Care and Use of Laboratory Animals" [9]. Each rat was housed individually in

suspended stainless steel cages and provided with food and water ^ libitum .

Twelve hours of fluorescent lighting per day were provided using an automatic

timer. All animals were weighed daily from the day of arrival until the end of

the post-exposure observation period. Control animals from the same batch were

weighed daily also.

2.4 Animal Exposures

Twenty- four hours prior to the exposures, one or two animals per experiment

were anesthetized with nembutal and cannulated. This procedure involved the

surgical insertion of a cannula into the animal's femoral artery [10], thereby

allowing blood samples to be taken before and during the exposure from

unanesthetized animals. The blood levels of COHb are indicative of the amount

of carbon monoxide inhaled by the animals

.

Six rats were exposed in each experiment. Each rat was placed in a restrainer

which was then inserted into one of the six portholes located along the front

^ Certain commercial equipment, instruments, materials or companies are identified in this paper in order to adequately specify the experimental

procedure. In no case does such identification imply recommendation or endorsement by the National Bureau of Standards, nor does it imply that the

equipment or material identified is necessarily the best available for the

purpose

.

5
of the exposure chamber such that only the heads of the animals were exposed to

the combustion atmospheres. Exposures were for 30 minutes, during which time

heparinized blood samples were taken prior to, approximately 15 minutes into,

and just before the end of the experiment from the cannulated animals.

The toxicological endpoint was death. The number of animals that died at each

mass loading of material was plotted to produce a concentration- response curve,

from which an LC^q (30 minutes and 14 days) value was calculated. The LCjq was

defined as the mass loading of material per unit chamber volume (mg/i) which

caused 50% of the animals to die during the 30 minute exposure plus the postexposure observation period. In this series of experiments, animals that were

still losing weight on day 14 were kept until they died or recovered as

indicated by three days of successive weight gain. These animals that died

after day 14 were also included in the LC^q calculation. The LC^q's and their

95 percent confidence limits were calculated via the statistical method of

Litchfield and Wilcoxon [11]

.

2.5 The NBS Toxicity Test Method

In the first part of this study, the acute inhalation toxicity of the

combustion products from the test materials was evaluated according to the NBS

Toxicity Test Method [5]. Briefly, the test method consists of three major

components: (1) a combustion system, (2) a chemical analysis system (see

section 2.2), and (3) an animal exposure system (see section 2.4) (Fig. 1).

The entire system is a closed design in which all the combustion products are

generated in a 1000 mi quartz cup furnace located directly below the 200 liter

6
PMMA rectangular exposure chamber (Fig. 2) and are kept within the chamber

except for the volume which is transferred for chemical analysis and subsequently returned. Temperature measurements in the cup furnace and at animal

exposure positions #1, 3, and 6 are measured continuously and recorded every 15

seconds by an on-line computer controlled data collection system.

The cup furnace is similar to that designed by Potts and Lederer (Fig. 3) [12].

Each material is evaluated under separate flaming and non- flaming conditions in

which the cup furnace is preset at 25°C above or below the material's

autoignition temperature, respectively. The autoignition temperature, in this

case , is defined as that temperature which causes the sample to flame

spontaneously during a 30 minute exposure. In the actual flaming exposures,

ethanol and/or an electric spark are used to ensure immediate flaming.

For this series of tests, additional experiments at temperatures other than the

standard ones (i.e., 25°C above and below the autoignition temperatures) were

necessary to estimate the toxicological contribution of each material when

tested in combination with the other. Therefore, the toxicity and test

atmospheric gases (CO, CO2 , HCN and O2

) from the polyester were also examined

at the non-flaming temperature of the polyurethane foam (375°C) and the test

atmospheric gases produced from the thermal decomposition of flexible

polyurethane foam were measured at the flaming temperature of the polyester

(525'’C) .

Combinations of the polyester and the polyurethane foam were thermally

decomposed in the cup furnace at a non- flaming temperature of 375“C (which was

7
the temperature at which the polyurethane foam was examined in the non- flaming

mode and the highest possible non-flaming combination test temperature, since

the polyurethane foam would flame at higher temperatures) and a flaming

temperature of 525° C (the temperature at which both the polyurethane and

polyester would undergo flaming combustion, if tested separately)

.

According to the NBS Toxicity Test Method, the highest concentration of

material tested should not exceed 40 mg/£. However, to complete this series of

experiments, especially those tests with combined materials, it was sometimes

necessary to exceed this limit. If no deaths occurred at the highest

concentration tested, the LC^q is listed as greater than that concentration.

2.6 Experimental Procedure with the NBS Toxicity Test Method

Prior to each experiment, the quartz cup from the furnace was weighed. The

furnace was preset to the desired temperature for the non- flaming or flaming

exposures. The material was cut to the desired weight and control blood was

taken from the cannulated animals. The animals in their restrainers were

placed into the front portholes in the exposure chamber. The experiments began

when the material was dropped into the heated cup and the door to the chamber

closed. Blood samples were taken during the 30 minute exposures and the

animals were observed to determine time of death as indicated by lack of

respiration. At the end of the exposures, the animals were removed, checked

for various physiological and behavioral functions, such as eye reflexes, nasal

and mouth discharges, breathing rate, righting reflexes, posture, and

exploratory behavior. Cannulated animals were sacrificed and not kept for the

8
post-exposure observation period. Animals sacrificed immediately following the

exposures were not counted in the LC^q calculations based on the 30 minute and

14 day post-exposure periods. If LC^q calculations were made based only on

deaths occurring during the 30 minute exposures, the cannulated animals were

counted. All surviving animals were replaced in their cages and weighed daily

for at least 14 days as noted above. The cup and residues were removed from

the hot furnace, allowed to cool, and weighed to determine the mass of material

consumed during the exposures . This information allows one to calculate the

LCjq values based on amount consumed per chamber volume in addition to that

based on the amount loaded, if desired.

2.7 The Cone Radiant Heater Toxicity Test Apparatus

The cone radiant heater toxicity test apparatus (Fig. 4) was similar to the NBS

Toxicity Test Method in that it consisted of three components: 1. an animal

exposure system, 2. a chemical analytical system and 3. a combustion system.

The animal exposure and the chemical analytical systems were essentially the

same as those utilized in the NBS method with the following exceptions: the

animal exposure chamber was the same size (200 i) and shape (rectangular) , but

was constructed of 25 mm thick PMMA instead of 12 mm in order to maintain a

vacuum. It was also reinforced with polytetrafluoroethylene- coated steel

supports. The animals received square-wave exposures to the test atmospheres

rather than being inserted first and experiencing the initial thermal

decomposition products of the materials. As in the NBS method, continuous gas

analysis was performed to monitor the concentrations of CO, CO2 , and O2 in the

animal exposure chamber during the 30 minute animal exposures. However, in

9
this case, because the animal exposure chamber was designed to be evacuated

prior to each experiment, the gas sampling line was equipped with a dead space

sampling loop that allowed for the intermittent gas sampling for HCN. A

thermocouple was installed in one of the pipe fittings to ensure that the

animal exposure chamber temperature was below the maximum allowable temperature

of 40° C before the animals were inserted.

The major difference between the two apparatuses was in the combustion systems.

Instead of a 1000 mi quartz cup furnace located below the animal exposure

chamber, the furnace consisted of a cone radiant heater enclosed in a separate

100 i pyrex combustion chamber. Below the cone heater, a load cell was mounted

to continuously monitor the sample weight loss during an experiment. Air flow

through the combustion chamber was controlled by metering compressed gases into

the bottom of the chamber. The combustion atmosphere was transferred from the

combustion chamber through a square pyramid- shaped hood to a horizontal exhaust

duct (114 mm I.D.); a portion of this combustion atmosphere was drawn through a

9 mm I.D. stainless steel sampling line to the animal exposure chamber and the

rest escaped through a main exhaust duct. The sampling line to the animal

exposure chamber was connected to a ball valve which manually controlled the

gas flow rate between the combustion chamber and animal exposure chamber. A

differential pressure transducer was connected to two points along a straight

section of the sampling line to allow for the actual measurement of flow rate

into the animal exposure chamber.

The cone radiant heater was similar in design to the heater used with the Cone

Calorimeter (Fig. 5) [13] and the ISO heater [14]. The heater was constructt-d

10
of a double wall (to minimize heat radiation to the outside wall) and contained

a heater element of coiled resistance heating wire packed in magnesium oxide

refractory and covered with a high temperature alloy sheath. The power to the

heater was controlled by a closed loop electronic controller connected to three

thermocouples located behind the coil windings. The heater could be set to

apply a relatively uniform radiation field over the sample surface from 0 to

11 W/cm^

.

2.8 Experimental Procedure Using the Cone Radiant Heater Apparatus

Prior to testing, the autoignition heat flux for each material was determined

by exposing a series of specimens to different incident heat flux levels and

noting the minimum heat flux necessary to cause a sample to self- ignite. In

general, if a specimen had not self- ignited within ten minutes, the incident

heat flux level was Increased. Actual testing was conducted with the incident

heat flux level set slightly below the autoignition heat flxix. This produced a

non- flaming exposure. In the flaming experiments, an AC electric spark

discharge was used to assure flaming once surface decomposition was sufficient

to develop a flammable mixture above the sample surface. This induction period

was short (5-15 seconds) for these materials.

Before each experiment, the combustion and exposure chambers as well as the

sampling pipe and control valve connecting the two chambers were cleaned. The

cleaning of the latter two items was necessary to prevent clogging of

components. The specimen material was cut to the proper dimensions - a face

size of 100 mm by 100 mm. The depth of the specimen varied with the test

11
material. When tested in combination, 76 mm of foam were covered on the top

and sides with one layer of fabric.

At the beginning of each test, an airflow rate through the combustion chamber

was selected. The cone heater was adjusted to the proper height to ensure that

the upper sample surface would be at the correct distance from the cone heater.

Power was applied to the cone heater and the heater controller was set to

maintain the cone heater at a constant temperature. A water cooled heat flux

meter was used to measure the actual heat flux incident on the sample surface.

When the cone heater was stabilized at a desired energy level, the heat flux

meter was removed.

While the cone heater was reaching equilibrium, the exposure chamber was sealed

at all openings. The inlet control valve was shut, and the analyzer lines and

the animal ports were closed. The exposure chamber was evacuated to

approximately 3 kPa or less of pressure.

The tests began when the material sample was placed below the cone radiant

heater on the load cell in the combustion chamber and the data acquisition

started. With the exhaust damper control opened approximately 40%, the sample

was allowed to decompose. Depending on the combustion mode, flaming or

non- flaming, transfer of the duct gases into the animal exposure chamber began

two to four minutes after the start of the sample exposure.

The animal exposure chamber was filled at a rate that was less than the

combustion chamber airflow rate. This sampling rate was maintained constant

12
throughout the filling process by means of a manual control, using the

differential pressure gage. Since the filling process was driven solely by the

pressure difference between the evacuated animal chamber and the essentially

atmospheric pressure combustion chamber, complete filling with combustion

products would take an infinite period of time. Instead, when the chamber was

filled to a pressure of 95 kPa with combustion products, the control valve was

shut. The exposure chamber was then filled to atmospheric pressure by

introducing clean air from a supply tank.

When the exposure chamber reached atmospheric pressure, the gas analyzers were

connected to the exposure chamber. The animal chamber temperature was noted to

assure that it was below the maximum value (40°C) permitted for the animals.

(It was possible to wait until the gases cooled before inserting the animals.)

The animals were then inserted simultaneously into the portholes along the

front of the animal chamber and received 30 minute square -wave exposures to the

test atmospheres. Treatment of the animals prior, during and following the

exposures were similar to that received during the NBS Toxicity Test.

2.9 Data Reduction for the Cone Radiant Heater Test Apparatus

The mass consumed (i.e., pyrolysate concentration) and transferred to the

animal exposure chamber, in units of mg/i, was computed assuming:

• instantaneous mixing of the pyrolysate in the combustion chamber; and

• no material loss on the interior surfaces of the combustion chamber,

exhaust duct, connecting pipe, and animal exposure chamber.

13
The latter assumption was found not to be strictly valid. Following each test,

the control valve between the combustion chamber exhaust duct and the animal

exposure chamber was disassembled and cleaned. Significant quantities of soot

and tar were observed to have deposited on the surfaces of the control valve

orifice and the upstream pipe leading from the exhaust duct to the control

valve. However, in these experiments, these losses could not be quantified.

Therefore, the calculated concentration values in mg/i reported in Tables 4, 5,

and 6 represent upper limit concentrations. The actual exposure concentrations

were less than the tabulated values.

A complete derivation of the solution of the relevant differential equations

used to calculate the pyrolysate concentration to which the animals were

exposed in each experiment is given in Appendix A. For the sake of simplicity,

the material loss response to a given external radiant energy field was divided

into a series of straight line segments. For a constant volumetric air flow

through the combustion, the exhaust material concentration was calculated for

each time segment. It was assumed that the animal exposure box was being

filled at the same concentration. For each experiment, the sampling flow rate

from the exhaust duct into the exposure chamber was constant as described

above

.

14
3. RESULTS

3.1 The NBS Toxicity Test

3.1.1 Flexible Polyurethane Foam

The autoignition temperature of the polyurethane foam used in these experiments

was 400° C. The chemical and toxicological data obtained from the flexible

polyurethane foam thermally decomposed in both the non-flaming (375°C) and

flaming (425°C) modes according to the NBS Toxicity Test Method are presented

in Table 1. This table also provides the chemical results obtained when the

polyurethane was degraded at 525° C, the flaming temperature at which polyester

was tested. In both the non-flaming and flaming modes, the residues consisted

of black light-weight chars.

Similar to other non- fire retarded flexible polyurethane foams tested in this

laboratory, no animal deaths occurred during the 30 minute exposures regardless

of the concentration (up to 40 mg/i) of the polyurethane or the mode of

decomposition - non-flaming or flaming [5,7]. Deaths were only noted during

the 14 day observation period following exposure to the non- flaming combustion

products (Fig. 6). The LC^q value for the non-flaming mode was 37.0 mg/.£ with

95% confidence limits of 29.8 - 46.0 mg/£. The LC^q value for the flaming mode

was greater than 40 mg/i , i.e., no animal deaths were noted either within or

post-exposure from any of the concentrations (up to 40 mg/i) tested.

15
3.1.2 Polyester

The autoignition temperature of the polyester fabric was 500°C. Therefore, the

polyester fabric was tested in the flaming mode at 525°C and in the nonflaming mode at two temperatures: 475'’C (25°C below its autoignition

temperature) and 375°C (the non-flaming decomposition temperature of the

polyurethane foam). The residue from the flaming and non-flaming thermal

decomposition of the polyester was also black but appeared heavier than that of

the polyurethane and looked like the remains of the melted sample. The

chemical and toxicological data collected from the thermal degradation of

polyester by the NBS test method are shown in Table 2

.

In the non- flaming mode at 475°C, the LC^q value of the polyester was 39.0 mg/i

with 95% confidence limits of 38.4 - 39.5 mg/i (Fig. 7 & 8) . Animal deaths

were noted both during and following the 30 minute exposures. At decomposition

temperatures 100°C lower (375°C), no animal deaths were observed at any time.

Therefore, the LC^q value at 375°C is given as greater than 50 mg/i , which was

the highest mass of material/chamber volume tested. However, it is important

to note that at the lower temperature (375°C), only 22-55% of the original

sample was consumed; whereas, at 475° C, approximately 85% of the sample was

consumed. Based upon a comparison of the toxicological effects at the actual

masses consumed at 475°C, deaths would not be expected at the masses consumed

at the lower temperature

.

16
In the flaming mode, deaths occurred both during and following the exposures.

Based on mass of material loaded per chamber volume, the LC^q value for the

30 minute exposure and 14 day post-exposure period was 37.5 mg/£ with 95%

confidence levels of 35.3 - 39.8 mg/£ (Fig. 8).

3.1.3 Flexible Polyurethane Foam and Polyester Combined

3. 1.3.1 Non-Flaming Combined Experiments

The thermal decomposition of both flexible polyurethane foam and polyester in

the non-flaming mode was studied at 375°C which was 25°C and 125°C below the

autoignition temperatures of the pol3rurethane and the polyester, respectively.

In most of these experiments, the polyester fabric was folded and dropped into

the cup furnace immediately preceding the polyurethane foam. In two

experiments, to be discussed later, the polyurethane foam was covered by the

polyester fabric. Upon heating, the samples collapsed in less than one minute

and formed a black ball in approximately two minutes

.

Since the polyester smoke was not toxic at 375°C even at the highest loading

tested (50 mg/i) , a sublethal amount of polyester (20 mg/i) was chosen to test

whether this addition would increase the toxicity (lethality) of the polyurethane foam in the combination experiments. If the polyester component has no

effect at this temperature, then the addition of 20 mg/i of polyester to the

LCjq value of the polyurethane (37 mg/>8) should increase the LCjq value of the

mixture by 20 mg/.8 to 57 mg/£ (Fig. 9). The results, however, showed that the

17
LCjo value of the combined materials only increased to 47.5 mg/i , an indication

that the polyester is contributing to the toxicity by about 10 mg/>? (Table 3)

.

Since a significant proportion of the polyester is not decomposed at 375°C,

these data were also analyzed on the basis of mass consumed/chamber volume. The

experiments on the polyester at 375°C showed that when 3.88 grams (20 mg/i)

were loaded into the cup furnace, 78% remained as residue and only 4.3 mg/i

were actually consumed. According to the same reasoning used before, that is,

under the assumption that the polyester at this temperature has no effect on

the combined toxicity, then the LC^q of the mixture of polyurethane (with an

LCjq of 31.9 mg/i , consumed weight) and polyester (a "non- toxic" amount of

4.3 mg/i , consumed) should increase by 4.3 mg/i producing a combined LCjg of

36.2 mg/£. However, the LCgg of the combination is only 26.2 mg/i , consumed

weight, indicating that the polyester increases the toxicity by about 10 mg/i

(i.e., 36.2 minus 26.2 mg/i) ; this is the same increase calculated when the

mass loaded, rather than mass consumed, was considered.

Two experiments were conducted to test the effect of covering the foam with the

polyester. In these cases, 47.5 mg/£ of the polyester fabric were needed to

cover the polyurethane. The results of these experiments indicated that there

was too much material in the furnace (i.e., the system was overloaded) to

produce accurate results (Table 3). Indications of the overload were (1) an

increase in the mass loaded in the furnace did not increase the mass consumed,

(2) the concentrations of CO and CO2 decreased with increasing mass, and (3)

the mortalities were fewer at the higher material loadings.

18
In those non- flaming experiments in which 20 mg/£ of polyester were added to

different loadings of flexible polyurethane foam, all deaths occurred during

the post-exposure period and none occurred during the 30 minute exposures.

These results are more characteristic of the experiments on pol3rurethane

decomposed by itself and different from those seen with the polyester alone.

No deaths were observed during exposure even when the polyester loading was

increased to 47.5 mg/i in the two experiments designed to test the effect of

decomposing polyurethane completely covered with polyester fabric (Table 3)

.

3. 1.3.

2

Flaming Combined Experiments

The experiments in which the flexible polynrethane foam and polyester were

combined and tested in the flaming mode were conducted at 525°C (25°C above the

autoignition temperature of the polyester) to ensure that both materials would

flame. A black residue was noted at the end of the 30 minute exposures.

In these experiments, the mass loading of polynrethane was kept constant at

3.88 grams (20 mg/£) and only that of the polyester was varied (Table 3). The

reason for this approach was the same as for the non- flaming experiments, i.e.,

to see if a non- lethal amount of the less toxic material (in this case, the

polyurethane foam) would increase the toxicity of the polyester whose LC^q

could be measured. The polyurethane foam when tested by itself in the flaming

mode at 425‘’C had produced no deaths either during or post-exposure at

concentrations up to 40 mg/i (Fig. 10); whereas, the polyester fabric, when

decomposed by itself in the flaming mode at 525°C, had produced both within and

post-exposure deaths. The LC^q value for the flaming polyester fabric by

19
itself was 37.5 mg/f , Therefore, if the polyurethane was toxicologically

inert, the addition of 20 mg/j? of polyurethane should have raised the LC^q

value of the mixture to 57.5 mg/i . In actuality, the 30 minute and 14 day LCjq

value calculated for the combined exposures was 39.0 mg/i with 95% confidence

limits of 36.0 - 42.2 mg/i . These results, showing that the LCjq value for the

combined materials was lower than expected by almost the exact amount of

polyurethane added to the system, are an indication that the polyurethane and

the polyester are both contributing to the toxicity in an additive manner.

However, since all of the deaths occurred during the exposures, the results of

these experiments more closely resemble those of the polyester tests rather

than those of the polyurethane experiments

.

Another way to examine these data is to look at the toxic effects of the

individual components of the mixture . For example , in one of the flaming

experiments shown in Table 3, 20 mg/i of the flexible polyurethane foam plus

20 mg/i of the polyester caused the deaths of 50% of the test animals; whereas,

20 mg/£ of the polyurethane foam decomposed by itself in the flaming mode

produced no deaths (Table 1) and the polyester decomposed by itself did not

produce any deaths below a concentration of 35 mg/£ (Table 2) . Thus individual

sublethal concentrations of this polyurethane foam and polyester fabric were

adding up to a concentration which was lethal.

20
3.2 The Radiant €one Heater Toxicity Test Apparatus

3.2.1 Flexible Polyurethane Foam

The radiant fliox at which the polyurethane foam would spontaneously ignite was

found to be 2.08 W/cm^ . The non- flaming and flaming experiments were,

therefore, conducted at 2.0 W/cm^ . Flaming was initiated by an electrical

spark. The experimental conditions, i.e., air flow, mass loaded, and gas

sampling times (times during which the animal exposure chamber was filled with

combustion products), and the experimental results, i.e., mass consumed, gas

concentrations in the animal exposure chamber, and toxicological data are given

in Table 4. The conditions were varied in order to generate the most toxic

atmospheres . For example , the maximum amount of sample was loaded into the

furnace and the air flow rates through the combustion chamber were reduced as

low as possible to minimize dilution effects. Regardless of the conditions,

however, no animals died either during or following the non- flaming or flaming

exposures

.

3.2.2 Polyester Fabric

The radiant flux at which the polyester fabric would spontaneously ignite was

determined to be 4.0 W/cm^ . The non- flaming exposures were performed at

2.0 W/cm^ which was the same radiant heat used for the examination of the

polyurethane. The flaming exposures were performed at 3.5 W/cm^ and flaming

was initiated by an electrical spark. Again, the experimental conditions were

21
maximized to produce the most toxic atmospheres. Table 5 gives the results of

the polyester experiments.

The maximum concentrations of gases transferred to the animal exposure chamber

under the non- flaming conditions were so low (approximately 100 ppm of CO and

650 ppm of CO2 ) , that it was deemed futile to expose animals. The exposure

chamber concentration of combustion products was calculated to be equivalent to

a mass consumed of <5 mg/Ji and since this was considered the maximum amount

possible, no further non-flaming experiments were performed.

The maximum amounts of gases generated under flaming conditions were higher

than in the non- flaming experiment and the concentrations transferred to the

exposure chamber were about 1900 ppm of CO and 5% CO2

. This combustion

atmosphere was also not sufficient to cause any deaths either within or

following the exposure.

3.2.3 Combined Polyurethane and Polyester Experiments

These experiments were conducted with polyester-covered polyurethane foam

samples exposed to a radiant flux of 2.0 W/cm^ . Again, conditions were

maximized to try to produce the most toxic exposure chamber environments

(Table 6). In the non-flaming mode, no animals died during the exposures, but

3/6 died during the post-exposure observation period. Two died during the lA

days and one died on day 25. A repeat of the same experiment, but with a

reduced air flow rate through the combustion chamber (which should have

increased the toxicity), produced no animal deaths.

22
In the flaming mode, the worst case conditions produced 5/6 animal deaths

during one experiment and no post-exposure deaths. An attempt to replicate the

same experiment resulted in no deaths (Table 6) . The reasons for the lack of

replication are unclear at this time.

4. DISCUSSION

A flexible polyurethane foam and a polyester fabric were thermally decomposed

separately and together in order to examine and compare the toxicity from the

single homogeneous materials and mixtures of the two using both the NBS

Toxicity Test Method and a cone radiant heater toxicity test apparatus.

The cone radiant heater toxicity apparatus was designed to explore the

toxicological effects of a variety of possible combustion environments needed

in order to expose non-uniform materials under normal performance conditions

typifying end use. Furniture composites, wall material composites, and

composite reinforced plastics have been satisfactorily tested in the Cone

Calorimeter for heat, smoke, and gas generation rates [13]. This capability

was considered an operational advantage of the cone radiant heater over the cup

furnace. However, the following limitations, not present in the cup furnace

apparatus, were found for the cone heater apparatus when used as a combustion

source in connection with a static animal exposure system:

23
• Determinations of the concentration of combustion products in the animal

exposure chamber. Difficulties arose in transferring a representative

sample and sufficient quantity of combustion products from the combustion

chamber to the animal exposure chamber. Another problem was the

determination of the mass of thermally decomposed material which

represented the amount of combustion products actually transferred to the

exposure chamber (see Appendix A)

.

• Transfer line clogging. The transfer line clogged badly due to soot

deposition. It was not considered desirable to filter or otherwise

eliminate the soot since this could selectively remove toxicants and

result in decreasing the measured effluent toxicity. The amount of

deposition required that the line be disassembled after every test,

cleaned out, and reassembled. It also meant that toxic products might

not be reaching the animals. This deposition might have been lessened by

heating the line, since a portion of such wall losses are due to

condensation and thermophoretic effects, which would be eliminated if the

line temperature were kept above the gas temperature. However, since

part of the line was located inside the combustion chamber, since a -

control valve was involved, and since the animal chamber temperatures

could be adversely affected, the design of a proper line heater became

quite difficult and was not undertaken. The decomposition of soot in the

stack between the combustion chamber and the sampling line also posed the

problem of potential carry-over of toxicants from one test to another,

especially if the testing mode changed from non- flaming to flaming.

24
• Filling rate control. The filling rate was controlled by monitoring the

differential pressure across a length of transfer line, and using the

manual control valve to maintain this pressure at a level corresponding

to a uniform filling rate. The relationship between the pressure

readings and the filling rate was pre- determined from flow calibrations.

In some cases, good control was difficult to achieve under all

conditions, i.e,, both with the animal chamber evacuated and with the

chamber nearly back-filled. A mass flow controller was considered but

was not implemented because significant difficulties were expected from

sooting

.

• Large reservoir volume in the combustion chamber. The Pyrex-enclosed

combustion chamber represented a substantial volume of approximately lOOf

if the exhaust piping up to the stack control valve was included. The

mixing and dilution of the combustion products with this volume of

initially ambient air would not be a problem if combustion rates and flow

rates of the air were rapid. In the case of low density foam, however,

only a small amount of specimen mass was available. Therefore, very

small combustion chamber air flow rates had to be set. Under these

conditions , there was a substantial error in determining the

concentration of combustion products in the combustion chamber, and,

consequently, in the equivalent mass loading needed to calculate the

LC5Q

.

Also, any effects of secondary combustion from heater hot surfaces

was dependent on the combustion chamber air flow rate.

25
• Test running time. It took about 30 minutes to evacuate the animal test

chamber. Another half hour or more was spent disassembling and cleaning

the transfer line. General calibration and setup for the system was also

substantially longer than for the cup furnace. Consequently, there was

at least a doubling of the time required to conduct cone radiant heater

tests compared to the NBS Toxicity Test Method.

With the NBS Toxicity Test Method, the LC^q (30 min and post-exposure) values

were easily determined based on the amount of material loaded into the cup

furnace or, when the residue was substantial, on the amount of material

consumed. With the cone radiant heater toxicity test apparatus, difficulties,

as noted above, were encountered in the determination of LC^q values. In some

cases, insufficient combustion products were transferred to the animal exposure

chamber. For example, even under conditions (i.e., low air flow rates, flux

levels close to the materials' autoignition energy levels, maximum amounts of

materials, etc.) designed to produce the maximum combustion products in the

animal exposure chamber, no animal deaths were observed during or following

exposures to either the flaming or non-flaming combustion products from either

material tested singly. Therefore, the LC^q values could only be listed as

greater than the highest concentrations attainable in the animal exposure

chamber. However, when the composite, consisting of the fabric covered foam,

was decomposed, some animal deaths occurred (Table 6) permitting LCjq values to

be estimated as approximately 30 mg/Ji in the non- flaming mode and somewhere

near 40 to 44 mg/i in the flaming mode. Lack of reproducibility prohibited

statistical calculation of these values. These estimated LC^q values were not

greatly different from those achieved with the cup (48 mg/i , non- flaming and

26
39 mg/i , flaming). These experimental results on the combined materials were

also similar to those of the cup furnace in that post-exposure deaths occurred

in the non- flaming mode and within- exposure deaths occurred in the flaming

mode

.

These experiments were also designed to determine if the combustion products

generated from the single materials would be equivalent to those generated when

the materials were combined. In both the flaming and non- flaming modes, the

average concentration of the primary gases (CO, CO2 , HCN) generated in the NBS

Toxicity Test system from the thermal decomposition of the mixture of the

materials appear to be approximately equal to (or, in the case of CO and HCN,

slightly greater than) the sum of the average concentrations generated from the

individual materials under the same conditions (Table 7) . This means that if

the concentrations of the primary gases that are generated from the thermal

decomposition of the individual components are known, then a reasonable

prediction of the gas concentrations from the mixture decomposed under the same

conditions can be made. It is important to note that the respiration of the

six animals in this closed system will produce an average gas concentration of

approximately 2600 ppm of CO2 in a 30 minute experiment. In the examination of

the additivity of gas concentrations from the Individual components , this

respiration- generated CO2 should only be considered once, since when the

mixture is tested, there is only the contribution of one set of animals. This

consideration is more important in the non- flaming mode since this amount of

CO2 represents a larger fraction of the combustion- generated CO2 than that

found in the flaming mode, which produces about 10 times more CO2

.

27
Closer examination of these results, however, show that the average HCN levels

from the flaming mixtures (Table 3) were higher than those seen in the flaming

exposures of polyurethane alone at 525°C which, in turn, were greater than at

425®C (Table 1). This difference becomes more apparent when the HCN generation

over time is examined rather than the average 30 minute concentrations.

Figure 11 shows the generation of HCN from 20 mg/i of the flexible polyurethane

when decomposed alone or combined with the polyester under various flaming

temperatures. The addition of various amounts of polyester to 20 mg/i of

polyurethane at 525°C produced greater concentrations of HCN than in any of the

experiments on the polyurethane alone (Tables 1, 3 and Fig. 11). This result

was unexpected since polyester contains no nitrogen and should not contribute

to the HCN generation. Figure 11 also shows that the HCN generation over time

from 20 mg/£ of flaming polyurethane foam alone tends to plateau during the 30

minute test, whereas, in the combination studies of this polyurethane (20 mg/i)

and polyester, the HCN continues to increase throughout the experiments. The

reason for this increased level of HCN is unexplained at this time.

In the flaming mode, the final concentrations of CO from the combined materials

also appeared to be greater than the sum of the final CO concentrations from

the individual materials (Fig. 12). This was more apparent from the graphic

representation of the actual time generation of CO than from the tabular

depiction of the average concentrations (Table 7). More experiments, however,

are necessary to eliminate the possibility that this effect is due to

experimental scatter. This apparent difference was not found in the nonflaming mode (Fig. 13).

28
The data obtained during this series of experiments also permitted the

assessment of whether the animal deaths could be attributed to the

concentrations of the primary toxic gases to which the animals were exposed.

Recent results [15,16] from this laboratory on the toxicity of CO, CO2 and HCN

alone and in various combinations have shown that the 30 minute LCjq for CO in

air was 4600 ppm. No animals died below 4100 ppm or post - exposure . The 30

minute LC^q for CO2 in air was greater than 18% (1% = 10,000 ppm). However,

when CO and CO2 were combined, the presence of 5% CO2 increased the toxicity of

CO such that animals died from 30 minute exposures to CO concentrations of

2500 ppm. Some of these deaths occurred during the first 24 hours following

the exposure. The combination of CO and HCN (30 minute HCN LC^g = 160 ppm)

showed the following additive effect:

If I.CQl

LC50 CO

. . I H_CN1

LC50 HCN

> 1 , the animals died.

When this formula equalled less than 1, the animals lived. Again deaths were

observed during the first 24 hours following the exposures.

Comparison of the CO, CO2 , and HCN concentrations that were produced in the

animal exposure chamber during the non- flaming and flaming polyurethane

exposures with recent results from toxicity experiments on these gases alone

and in various combinations [15] Indicated less than lethal concentrations of

these gases in all tests (Tables 1 & 4) . For example, with the NBS system, at

the highest loading of the polyurethane (40 mg/i) , the average concentration of

CO during a non- flaming experiment was 740 ppm, CO2 was 2500 ppm, and HCN was

below detectable limits. In a flaming experiment at 40 mg/i , the CO was

29
840 ppm, CO2 was approximately 33500 ppm, and HCN was 27 ppm. All of these

gases, even if considered in combination, were not sufficient to cause

lethality at these concentrations. Therefore, the post-exposure deaths from

polyurethane seen in the non- flaming mode in the NBS system were due to one or

more toxic combustion products or some other undetermined factors that were not

measured in these experiments. These deaths were noted as late as 14 days

following exposure.

Examination and comparison of the average gas concentrations that were

generated during the lethal NBS Toxicity Test Method non- flaming polyester

experiments with our pure gas toxicity experiments indicate that the average CO

levels were 56-63% of that necessary to cause death by CO alone

(4600 ppm) [15]. The maximum CO levels in the lethal experiments were 78-89%

of the lethal CO concentration. The average CO2 present was about 10% of that

necessary to increase the susceptibility of the rats to lower levels of CO

(e.g., 50,000 ppm of CO2 caused rats to die at approximately 2500 ppm of

CO [16]). The COHb levels at the end of the 30 minute lethal exposures were

75-83%. In a separate series of experiments in which the animals were exposed

to pure CO in air for 30 minutes, no deaths were observed in animals with COHb

levels below 83%. These results indicate that CO was contributing to the

within- exposure deaths, but that other toxic or irritant gas(es) or

undetermined factors were also acting in conjunction with or to potentiate the

effects of the CO. The cause of the late post-exposure deaths is also

unexplained.

30
Non- flaming experiments on the polyester in the NBS system at a lower

temperature (375°C) produced no deaths even at concentrations as high as

50 mg/-?. The gas data were in agreement with these results.

Examination of the gases generated during the lethal experiments from different

mass loadings of polyester decomposed by the NBS Toxicity Test Method in the

flaming mode shows that the average CO varied between , 2300-3000 ppm and the CO2 varied between 2.7% - 3% (1% = 10,000 ppm). In these lethal experiments, the

COHb levels ranged from 83-85% and the rats died within exposure or shortly

thereafter. These COHb results would implicate CO or CO plus COg as the main

toxicants. However, the average CO was approximately 50-65% of the lethal

concentration determined for CO alone. Even considering the synergistic effect

of CO2 on CO, the average values of CO and CO2 from flaming polyester were

still too low to account for the deaths that occurred during these 30 minute

exposures. Only if one considered the maximum CO levels along with the CO2 concentrations would the deaths be predictable.

When the polyester was decomposed in the flaming or non- flaming mode with the

cone radiant heater apparatus, there was not enough CO and/or CO2 transferred

to the animal exposure chamber to cause any deaths

.

The NBS Toxicity Test Method experiments on the combined polyurethane and the

polyester indicated that both materials contributed to the resultant toxicity.

In the non-flaming mode at 375°C, 20 mg/i of the polyester (a non-lethal

concentration at this temperature) increased the toxicity of the combined

materials 10 mg/-? over that expected if the polyester were truly non- toxic as

31
indicated when tested alone at this temperature. All deaths occurred during

the post-exposure period in a similar manner to that observed with the

polyurethane by itself. The concentrations of measured gases (CO, CO2 , HCN)

that were generated during these exposures were not sufficient even in

combination to have produced any within- exposure deaths. These measured gases

were also not responsible for the post- exposure deaths that occurred.

Some post- exposure deaths were observed in the non- flaming combination

experiments conducted with the radiant cone heater. In these combined

experiments, the gases transferred to the animal exposure chamber were not

sufficient to have produced within- exposure deaths and no such deaths were

observed.

When the combined materials were tested by the NBS Toxicity Test Method in the

flaming mode at 525°C, both materials contributed in an additive fashion to the

combined toxicity. The LCjg (30 min and 14 day) value of 39 mg/i resulted from

the addition of 20 mg/i of the polyurethane to 19 mg/i of polyester, although

concentrations (ranging from 20-40 mg//?) of flaming combustion products from

the polyurethane alone caused no deaths. In other words, a non- lethal amount

of the polyurethane (20 mg/i) plus a non-lethal amount of the polyester

(20 mg//?) caused 50% of the animals to die within the 30 minute exposure.

Examination of the average gas concentrations of CO, CO2

, and HCN which were

generated during these flaming exposures and comparison of these gas values

with our pure gas toxicological studies shows that the concentrations of these

gases were sufficient to account for the deaths that occurred.

32
In the flaming combined radiant cone heater experiments, the levels of CO, CO2

,

and HCN were also sufficient to account for the within- exposure deaths that

occurred.

5. CONCLUSIONS

A flexible polyurethane foam and a polyester fabric, two common components of

commercially available upholstered chairs were examined with the NBS Toxicity

Test Method and with a cone radiant heater toxicity apparatus. In both cases,

the fabric and foam were heated individually and then together.

The NBS Toxicity Test experiments indicated that for the individual materials:

• The decomposition products of the flexible polyurethane foam produced no

deaths during exposure and only caused post-exposure deaths in the nonflaming mode

.

• The polyester when decomposed 25 °C above or below its autoignition

temperature caused deaths both during and following exposures

.

Comparison of the CO, CO2 , and HCN concentrations generated from the individual

materials with pure gas toxicity experiments (performed with single and

multiple gases) indicated:

• The deaths from flexible polyurethane could not be explained by the

concentrations of these gases.

33
• Non-flaming polyester produced relatively high COHb (75-83%) levels, but

lower than lethal average or maximum CO concentrations. Even when CO was

considered with CO2 (which acts synergistically with CO) , the combination

was not sufficient to account for the deaths.

• The deaths from exposures to flaming polyester products were probably due

to CO since COHb values were 83-85%. In this case, the maximum (not the

average) concentrations of CO plus CO2 were sufficient to predict the

deaths

.

Results of combusting combined materials in the NBS Toxicity Test Method

indicated that:

• Depending on the amount thermally decomposed, both materials contributed

to the combined toxicity. In the flaming mode, the contribution was

additive

.

• Similar to the polyurethane results, the non- flaming combined experiments

produced only post-exposure deaths and these could not be explained by

the generated CO, CO2 , and HCN concentrations.

• The deaths obseirved from the flaming combined experiments were

explainable based on the concentrations of CO, CO2

, and HCN.

34
Comparison of the gas concentrations from the combined materials with those

from the individual materials indicated:

• The non- flaming yields of CO, CO2 , and HCN appear to be approximately

equal to the sum of the yields from the single materials.

• The flaming yields of HCN were greater than the sum of those from the

single materials.

The cone radiant heater toxicity test apparatus, as currently designed, did not

provide good reproducible results. LC^q values could only be roughly estimated

for the combined material experiments; these values (approximately 30 mg/i in

the non- flaming mode and somewhere near 40 to 44 mg/.? in the flaming mode) were

not greatly different from those achieved with the cup furnace (48 mg/i in the

non- flaming mode and 39 mg/£ in the flaming mode). The results that were

obtained showed that the concentrations of the primary gases in the exposure

chamber could be used to predict whether deaths would occur. In the

experiments on the combined materials, the cone radiant heater results were

similar to those of the cup furnace in that post-exposure deaths occurred in

the non- flaming mode and within-exposure deaths occurred in the flaming mode.

The results of this study have shown that satisfactory toxicity screening

results on composite materials can be achieved with the use of the NBS Toxicity

Test Method. Composites for which it is known that the surface materials do

not offer a substantial fire barrier protection to the underneath layers can be

35
tested simply as an agglomeration, instead of a layered composite. (At the

other extreme, interstitial materials which are very adequately protected from

fire involvement by the surface layer may not need to be tested at all.) There

is an intermediate regime, where the surface layers act to slow down, but not

to wholly eliminate, the burning of the underneath layers. If a detailed

characterization of such construction is required, it is possible, in principle, to determine in the Cone Calorimeter the relative involvement of the

layers, and then to conduct several NBS toxicity tests using individual materials or combinations.

6. ACKNOWLEDGEMENTS

The authors appreciate the help of Dr. Vytenis Babrauskas and Dr. Richard G.

Gann in various aspects of the design and review of this study. Laura Baier,

Trudi Holt, William H. Twilley, and Gerald King and J. Randall Lawson

participated in the experimental work. This work was supported in part by the

Consumer Product Safety Commission, Washington, DC; Dr. Rita Orzel was the

Project Officer for the Consumer Product Safety Commission. The conclusions

are those of the authors and not necessarily those of the Consumer Product

Safety Commission.

36
7. REFERENCES

[1] Fire in the United States, Second Edition, Federal Emergency

Management Agency, FEMA-22, July, 1982.

[2] Literature review of the combustion toxicity of flexible polyurethane

foam. Status Report on Fire Combustion Toxicity, TAB-B. Consumer

Product Safety Commission, Washington, DC 20207, 1984.

[3] Braun, E. and Levin, B.C., Polyesters, a review of the literature on products of combustion and toxicity. NBSIR 85-3139, Nat. Bur. Stand.,

Gaithersburg, MD, 1985.

[4] Alarie, Y. , Stock, M.F., Matijak-Schaper , M. , and Birky, M.M.

,

Toxicity of smoke during chair smoldering tests and small scale tests

using the same materials. Fund. & Appl. Tox. 619-626 (1983).

[5] Levin, B.C., Fowell, A.J., Birky, M.M.

,

Paabo , M. , Stolte, A., and

Malek, D. , Further development of a test method for the assessment of

the acute inhalation toxicity of combustion products. NBSIR 82-2532, Nat

Bur. Stand. Gaithersburg, MD, 1982.

[6] Levin, B.C., Babrauskas , V., Braun, E. , Gurman, J.L., and Paabo, M. , An

exploration of combustion limitations and alternatives to the NBS

Toxicity Test Method. NBSIR 85-3274, Nat. Bur. Stand. , Gaithersburg, MD

1985.

[7] Levin, B.C., Paabo, M. , Fultz, M.L.

,

Bailey, C., Yin, W. , and

Harris, S.E., An acute inhalation toxicological evaluation of combustion

products from fire retarded and non- fire retarded flexible polyurethane

foam and polyester. NBSIR 83-2791, Nat. Bur. Stand. Gaithersburg, MD,

1983.

[8] Paabo, M. , Birky, M.M.

,

and Womble, S.E., Analysis of hydrogen cyanide

in fire environments. J. Comb. Tox. 6-99-108 (1979).

[9] Committee on Care and Use of Laboratory Animals, Guide for the care and use of laboratory animals. DREW publication No. (NIH) 78-23.

U.S. Dept, of HEW, Public Health Service, National Institutes of

Health (1978)

.

[10] Packham, S.C., Frens , D.B.

,

McCandless, J.B., Patajan, J.H., and

Birky, M.M.

,

A chronic intra-arterial cannula and rapid technique for

carboxyhemoglobin determination. J. Comb. Tox. 1:471-478 (1976).

[11] Litchfield, J.T., Jr., and Wilcoxon, F. , A simplified method of

evaluating dose -effect experiments. J. Pharmacol, and Exp. Therapeut.

96:99-113 (1949).

37
[12] Potts, W.J., and Lederer, T.S., A method for comparative testing of

smoke toxicity. J. Comb. Tox. 4:114-162 (1977).

[13] Babrauskas , V., Development of the cone calorimeter - a bench-scale heat

release rate apparatus based on oxygen consumption. NBSIR 82-2611, Nat.

Bur. Stand., Gaithersburg, MD, 1982.

[14] Technical report ISO/TR 5657-1982 (E)

,

Fire test-reaction to fireignltabllity of building materials. International Organization for

Standardization, July, 1982.

[15] Levin, B.C., Paabo, M. , Gurman, J.L., and Harris, S.E., Effects of

exposure to single or multiple combinations of the predominant toxic

gases and low oxygen atmospheres produced in fires. Fund. & Appl. Tox.

(Manuscript submitted for publication)

.

[16] Levin, B.C., Paabo, M. , Gurman, J.L., Harris, S.E., and Braun, E.

,

Toxicological interactions between carbon monoxide and carbon dioxide.

Toxicology (Manuscript submitted for publication)

.

38
No.

died

LC5

o

Initial

Type

Mass

No.

tested

Latest

30

min.

Temp.

of

Chamber

Vol.

Average

Gas

Concentration

^

Max.

Highest

Within

Within

Day

of

+

Material

AIT

Mode

of

Expt.

Expt.

Loaded

Consumed

CO

COj

Oj

HCN

CO

X

COHb

Exp.

&

Post

Death

lA

days 0£B

E

6a

Ba

B

p.

ocB

u

B

fco

o •

• <•

vO %0 lA lO Z *-H t-H rH cn

'O 'O 'O vO

cn o

^ § soCM -4' 0000 <T G Q O m 00 o r-» ocs

00 m 0000 CS CN (Ni 0000 o OS o p o

m %o 00 z CS CM <S CN

o o o o p o

04 fs» O O Z O r'' vO o*.

cn Os so <r •-« m

o 00 o o o o

o O' o 04 m o t-H f-H m m m

< Pi Pi Pi pi^

lA LO lo lA

pN. r>. 1*^ fN. n cA fO <A fO n

o

o

-4f

0)c«

I x:

>> 4-* rH 0) m

o u ^

o<•

< < < <

z z z z

so vO z o o o

so sO sO z o o o

vO

0000 -H Os

04 m lA O'

< < z z

c < z z

0 o

01 m

r'* ^4

os 04 <f

O' 00 r>. sO 0000

*4^ *4 lA

00 .-H 00 (A

04 01 m 0000 o*. 04 04 <r

»-t (A lA 00

O*. OS 00 «-H

0000

0000 rH 04 rO '4’

c pE^ pe: PE^

lA OOS 00

o o

fO O'

sO (A

OS OS OS OS

O O

04 04

< <

0) (A U r-4

Q>U

(d T)

0) 4Jm

04

<r 'd* <T lA lA <d 4J M c

0) C s

0) •H 0

c 01 0 a 4-» *0 0) u tK c 0) rH

0) c

V) fi •H Cd

cd •rl p a

00 cd M •H 0 0> 0) rH 0 <D •H CL 00 0 00 K 04 o. c

(d (p (d *H rH s

0) Cd 4J 4J 4J cd > Cd 0 0 rH < 2 P(^ z Z Oh

0)c

(d

» XJC < X §

< pH Z 4J 0)

39

AIT.

Auto-ignition

temperature

*.

95Z

confidence

limits

FPU

13.

Flexible

polyurethane

//13

PE.

Polyester

Comb.

Combined

weight

of

FPU

13+

PE
Toxicity

Results

for

the

Polyester

Fabric

Using

the

NBS

Toxicity

Test

Method

• w

C

o -H (d m a + "O (H o a JO St M r-4

(0 O J 0) J

4-> >> ed

Id 01 HI J Q O

•o J o

0) j

3 tO

•P J c

in W -fi 0) o a J o

00 o •H !•< m

s

X o a dun z: o

zo

ffi o

o a

o o

T3

<D >

O (A > c a

o

U O

0)% T3 ^ 0) O T3 ^

CO U

o a

HI 4J SM Q* O X H

•H Qd >< 4J a M o

•H S

C H • M O

0)OX

H O M o <

CO r:

C < CM CM (N Z Z Z Z

'4‘ <r m so iT> vo o o o m m ro IT)

sO sO sO sO sO sO sO O O O rH CM rM ^

sO 00 m o o

^Z»-<r^mo\rMm.—

I

00 so 00 r>> 00 CO ooooooooo p^fOso*^oososfnfn cMm-4'»-*osinor^oo f-»(MmfOco<o<rrifn

r>*soio<t<^'«5’<^'4'<r ooooooooo CM(M<M<MfMCM<M(MfM

oi/^r^r-tosin<MOos OOOOOOOOO

p'-ior^ostono'foos

*HCM'4’'4’iT>lOiOiO*^ OOOOOOOOO

OssO'^cnOOiOOssOsO

»-»CMCMCM(M(M<M(M

<j'msoosm'4'fO(Mas

OOOi/^*-«iOlOCMO

<<0eipiiP;iKp::ipeiOi

-^''-O'rorosommmm

p^rvr>.r^r^r^r^r^r^

< < z z

><<'10 Z o o

< so so Z o o

in CM < • • Z fO lO

o o o so < .-H 00

o o o

CM CM CM O O O 00 ^

sO O'CM (M

O O O lO eH

CO <

< o

CM CM

O O O

CM < m

< (xi ai

so

rro CO CO

o

o

lO

0)>>

ir> CO

rv ro

< lO vO lO o CM CO <

sO sO sO sO O *-H <0 <

O O CM so

O O O O OS O sO f-« OS < 00 CO

CM CO CO <

< CM O 00

00 00 00

o o o o

o o o CM CO lO lO m 00 o

CM CM (M CO o o o o

CM OS < OS

CM CM O OS CM CM CM CM

r>. r>. »-H 00

o o m o

PC ai oi PH

lO CO <

CM CM CM CM

to lo m »n

(0 H

019

TJc

0)oo

40
Toxicity

Results

for

Flexible

Polyurethane

//13

Plus

Polyester

Using

the

NBS

Toxicity

Test

Method c o •H (d m 6 + 'd U

hJOcn

+J M-l V) 0 x:

0) 4J

4-> s <d

cd (d 0) u o CJ c

*H

w

T) x: o

•o 0) ij 04

0) 4J r4 •H 0) ca t3 0) 4J • c o • • z o a z 4J X

03 3

0) o

x:

u

MlOn

XO 6

rO CJ

a

r

Q

puiM (X SOX H W

fH • 4J

ctJ 0< •H a X 4J 9 (J

.H

H

dM

O

0) “doXHM

Oo I mom

r>*m

M < ^ m

•< 00 fsiO fN fNl Zo <N r> r> •4’

vO vO nO vO *0 \0 vO ^ O O O O O O

O' <T O' O' O' ^ vo m m m <f o m rj fo <r m m <! o o o o o o o

O' 'O rJ •—< 'O

m

00 O' CM <r 00

m

VO NO o o

(S

cN rJ

4J

mm

m cn < m NO c P4 S) O o o o o o o o o o o •w' ts csl CM CM cM CM CM CM CM coo o o o O O O O O O V) r4 f3 o fvl o CM m ON CM

*d o O NO O' 00 00 o m NO o u o (N cn m cn cn cn cn CM

'w'

0)M

(dp o o o o o o o o O

0) El O' r>>*m cn o ON NO 00 00 > o a NO NO 00 cn cn 00 cn < u o 1-4

*d

0) p**v g o OJ CM 'dm ON

V) ob NO cn

m r>* cn NO c bi CN| csl cn cn m cn oo

jQ o m o m o m o 'dm o o r*^ o <M m r>. o CM o <r m m m m NO 00

*d

0) e>j o o o o o o o m

m T3 03

(dM 04 o o o o o o o o CM <N| (M CM CM CM CM •<r <r hJ m O m o m o m o ON 00

;=>

O o (Mm r-*. o ON -d 04 CM cn cn cn cn -d CM

OeSCdpelat^PESOeiO:; QtScX m m m m vo m

r<. r«. r». r>* m rn m ro m ro

m

NO

m

mm » JS

w >> O ^ 0)

m

I—< O

M

aa 0 ^

•je I O O (S

O'

O cv| r> CO <3- < < < < z z z z m m no 'O nd

f—4 m

m NO NO

nO 'O 'O

O nO

f-H

m

m NO NO <z o o o o o

CM rJm o m *-i ON m (N| m rn m

rsi

m o 00 ON

NO NOm <fm

m •—« <T 00 •—<

r»» no o o o o o o o

rJ NO o CO ^ < <r CO m CO m cn o o o o o —I 00 C" 00 rJ <f o -H (N rJ CN| ro O ON 00 o o

00 *H ^ ON

m

m <f <r o o m o o o o m o o o o o o o

02 od 05 0(3 m m vf

fvi oJ

r4 (NJ oJ

mmm

mm oo

0) 0) 4J c

(/) (0

0) I jn

>»W >» 4J

r-4 0 i-» 0) o •-* o M

OM O.

a 0

ON

NOom

ONoooo 0H

010) m

T3co

00o

41
TABLE 4 M

0) 4J

0)

tri 4Jc

a) •H

nj

0)cou

0) X

00cw

Oi

j::

0)

p-H Xi

P*4uo

(00)

pc:XoH

w

C

•H

W 4

-J 0) S P w

rH 4J 4J iH 0 P « •H cx a w

0) pi

pH 0

Jj 3 1 c d

•H

u

•d s p

B 0) +J

w

•rH •H •H 0 5

*d ^ g

pCo

0)M

:3

(AOaX

(DUCo oc u r Z 00 G u > a sea M 00 ^ o > ^s e w

n)C

•iH CM4-I

B

O aJ

L? • Q

4J

CTJ cHIM

B

O Oi a • a

4J

f-l o

n) <D *H 0) 4J .. H C C «H M e P o e oj ^ X 0

O. P u X r-H U M-i 3

vD vO vO \0 O O O O

vO v£3 vO \0 O O O O

fNi O' lO O'

(N| 1—I T—I CNJ

vo

m vo O' o o o o r- 00 <T m

00 vom

—I

•<r

m

m ro o o o o o hs. \0 vO O' o o o o m <r O' vO ro o o o o o (Ni NO m tn

<r inm o m m 00

r>> \o

m »—• o o 00 O' m M r-<

vo vo vo o o o

nC sO <0 o o o ^ vO

\o tn

m o o o

00 <f m 00 00

p— *<f o o o O 00 o

r- o o

vO rJ

—< m <r o n o

<T 00 o m o o o o

nj O' -4^ ^ vo ^ n O' m —t O'

rn

m ro

O

cs

C

00

•r^opeMV4 <0O4

>y JO

•o

0)

•O

0) 4Jup

•ocoa

0)uo3c

0)0

•rJ

l-l <Do.X

01 < “d

J=

d

Xu c

•H *H 00

•d s 0 c C 9 u •H

0)d 0

Ok 4J 4Jd 00 0. d d ^ c c •d VM -*H • a

0) 9 4J c §

0) iH 0 0 ^

CO

b z Z CS4

42
Toxicity

Results

for

the

Polyester

Fabric

Using

the

Cone

Radiant

Heater

d

•V •H

m ^

0) -C

d

w

4J 4J r-» 0

(0 •H CXa

<D 3 1 4J C 0)

•r^ Xl •d jd d

0) 4J V)

•rH -H 0

*d 3 aX

Pe3

cd ^U o<zo<zV 3O Z 00 6 u > a K C Q I >

(dc

•iH CMIM

B

O OJ U • 3

«dc

•H

u-i 6 o -- OJ O • Q

•d

(n ti C W (0 o c w o o V)

•r4

d

4J z •r^ •d

tj 0) ^ c *d oc o cd o o

r—1 u

0)a

Cd c 3 ‘H o u o a

•H c c 4-4 o? o >s_^ N

AJ

K

a

cxd o

[3 iw ^

01 *ooz om

VOoin

vOO o

00oo

O'

fNl 00 o m

CMn c

005 • << t/i 4-» u • ;3 M O

(d

u

cx cx

tn

,*-«s u 4J

0) 0)

O

O *H

a *d to

OOC • r4 C •• • » •• H Cd C 00 (V| •w ^ to 0( a cd C 3

•r^ 1-^ 00 a c a I-H o •H d cd 0) a

cn •Hw o o cd 4J •• O O r-l to •H C •• •• C*4 cd C *H M M O M 6

'w' •

(da 4J

•H

w

u 0 4J X) u a 0) o

r-< o 0) 4-1 c o

(d V) >» c

-O o

-d 4J 0) cd

0) -H u ^ a) 4J 3d •d

0)

d

a to

•r4 o u cx

0)

X

cxd

Xd

d

-<

u •d d d

X o 3 d

•H »H •H 00

*d

X toa

d

d 3 1-^

u •H

0) 3 d

a

cx 4J

a 4J

d 00

Ou cd •rH

dd < d •d 4-4 *H X cd ' a d d 4J d d d o o o •-< tn 4-« c c d 4-4

A3
TABLE 6 0

(A tj •H to 4J

4-» 0) 0 (0

i-H 4J 4J

O 0 to H cx a w 0) 3 1 0) 4J PS C 0) —

•H Vi xJ ^ 0 B <3) 4-> to

«r^ •H • 1-1 o q XJ 3 a

-2

Xw

VOO

(TJOC ^ O U o e

tc • ^00 a

4J C3 > a q ca < a

•HqfX 00^

0) to o > w c c < w o o o •H

iJ

0) cdVi cd

4-> 4J c c •ri 06 0) g-t S C (0 o o a c c u • D

to o o 4Jw :i3 .ri o •ri 4J c

Vi Ti to

0) X3 «d

•VJ

C o to o

0)

u fdc

--t Vi »ri O 0) M-i

a

Oi o a a tj • a

to 2 iJ

w•ri r-l o c

doM

0) ro Vi ^ 0

to /«~v o U

0)

a 0) 0)

C

X

a x> to

(«

M c •• 43 H cri c

4J -ri 0) OQ s

Vi

C

p r~i 1— Qi o a 1—1 O

Pi CD cd 0) m •ri to

Q) iJ •• rH to •ri C

43 nj

C -H •H O M S X

0)

CNI o

VO

X?

Vi 0) o Q

IM 3 V to Of

to c

to o

c: to o P o W)

to ri cd

0) VJ

r

PS • ri X3

x> 0) /T-N >> c X3 Of 4J o «d

•ri

u o u r—< •ri Vi X 0) o 43 H a yr~N CD c

x: • ri u Vi o a

•ri c < g-4 Oi o m

rvi o

<r

vO

in o

<r <r

00

M fsj o oo

CM CMO mm <r

fsl (N m in

0*4 rsi o

fN

CX4

MU

<da

>s

Xi

0)

<0> • m OOCsl c

•H >s Q

?3 t3 • t3

0) ^ *r4 4J TU U3 a> T> c c o o

Q) >s

|4 CQ

0) T3 C C V y

PuK -O V a» x: *o

KU

M-l ^4

M

TJ ^ c y 0) a

Ou *J o. c

•<

01 ^ <o

i« X>

O -o ( g ^

44

0]

added

to

exposure

chamber.

0,

added

to

exposure

chamber

which

was

then

backfilled

with

air.

not

determined

non-flaming

flaming
Table 7

Gas Concentrations from the Thermal decomposition of

Polyurethane Foam and Polyester Alone and in Combination

by the NBS Toxicity Test Method

Mode Temp.

(°c)

Material

Mass Loaded Average Gas Concentration^

Chamber Vo lime

(mg/ 2.) CO

(ppm)

CO 2 (ppm)HCN

(ppm)

Flaming 525 Polyurethane 2o2 510 (+ 120) 14900 (+ 4200) 44 (+ 7)

Polyester 30 2220 25200 —

Total 2730 40100 44

Polyurethane 20 3070 34700 59 + +

Polyester 30

Non- 375 Polyurethane 30 700 2690 4

Flaming

Polyester 20^ 50 600

Total 750 3290 4

Polyurethane 20 850 3400 5 + +

Polyester 30

1

Average gas concentration:

integrated area under instrument response curve for 30 minutes _ ppm-min

30 minutes 30 min

2 Results are average + range of two analytical experiments

3 Analytical experiment (no animals)

45
Af)

Figure

1.

NBS

Toxicity

Test

Method

ar.iaial

exposure

chaaber

aad

furnace
47

Figure

2.

Schematic

of

NBS

Toxicity

Test

Method

and

gas

analysis

system
1000

ml

QUARTZ

BEAKER

92

mm

0.0.

15

cm

high

48

HEATING

ELEMENT

IN

BOTTOM
H > Pu

W4J

cdU

cfl PuIX

Cd

4-1 CO

cu -Pp

•Ho

•H

><! OPU

(U P

cd(1) pc

03 •H

03U

<UCOO

(Uu

p)bO

•H

Pm
TOP

OF

FURNACE

OPEN

TO

50

Figure

5.

The

cone

radiant

furnace

in

vertical

and

horizontal

modes
Figure 6. Concentration-response curves for flexible polyurethane

foam (NBS Toxicity Test Method). All deaths occurred

during the 14 day post-exposure period

51
(sAep PI + uioi oe) SH1V3Q %

T3

(U

COO

c o

(U c u

C (1) oU iJ

(U

»-> 3

00

•H

52

MASS/CHAMBER

VOLUME

(mg/I)
100

O)B

lij SDO>

QC

LU

00s<Xoa

UJo<o

(/)

(/) <

(sAep uiui 0€) SH1V3Q % oc s tu (U O > 4-I cow O rO CU O C H

00

(Ucc

oo

*H

53

tration

response

curves

for

polyester

decomposed

25°

and

below

its

autoignition

temperature

(NBS

Toxicitv ^

4-U 3\^
100

OJ

•>

m

dj c C O o js 4-j a

I-H CJ cn

M c

ro ’H (u (u TO H

J-l 3 I >4-1 <u c o 4J 4-4 4J o W O *H *H 1—4 0) 0 4-1 '^

<—I "H dj ao

1—4 iH

X

M

B

O 03

O 4-1

a

H c o •> 0) CN « ^ C/3 a

<U I-H PQ

p 4-1 c z o o o 00^0

>—t B c

CO CJ i-l o O o 03 tH

(U CMm CJ 4-4 liJ c •H •H 0) ro 4-1 TJ s -C V-I 04 T3 3 4J 04 4-1 3

-< CO

04 4-1 03

O

CO 04 04 o p 04 04 s: rC

P>s >> X) 4-4 4-4 > 1—4 r-4 O o O B T3 CO oc a a

ao

04c p

»—4

LU •X3 c •H

a

tn o C -H -e 4-1 CO B B 04 s CO o c

cn 04 r-^

u CO < 04 C 4-1 J= X > CO 1 04 4-4

4-1 JZ c j: 04 o P 4-4 O 4-4 Ui \ O 04 C

CO P o 04 P 04 •H rH UJ cn J= o c .-4 4J C a. o o O 5 a a c o 04

CO • 1-4 JC JZ o 04

)->

>4-1 O

T3

CO 4.1 -J 1 04 o c c 04 CO CO o 03 (/)

(/) o »-

O 1—4 -H •H P D. < X) i-l 4-< 4J B 04 03 < CO X O CO 4.1 u •H CJ • CO m 2 4-1 B 04 ^•N .O g c T3 T3

04 <0

O 04 4J

CJ 04 x: > c T3 ^1 4-4 U 03 o C 04 04 P C u CO 3 X. U •H

(T<

lUu3

ao

(sAep ^1. -uiui oc) SHivaa %

54
100 (sAep tr|. -uiuj oe) SHXV30 %

55

Figure

10.

Concentration-response

curves

for

polyester

alone

(flaming,

525®C)

polyurethane

alone

(flaming

425°C)

and

polyester

plus

polyurethane

(20

mg/1)

decomposed

in

the

flaming

mode

at

525°C

(NBS

Toxicity

Test

Method)

.

Also

shovm

is

the

combined

theoretical

concentrationresponse

curve

based

on

polyester

plus

20

mg/1

of

an

inert

material.
Figure 11. Generation of hydrogen cyanide from polyurethane decomposed

in the flaming mode in the NBS toxicity test apparatus. In

all cases, the mass loading of polyurethane was 3.88 g

(20 mg/i). Polyurethane decomposed alone at 425'C (-) or

at 525‘’C (—, A—A); 20 mg/i polyurethane at 525*C with

polyester at 22.5 mg/i (A), 25 mg/i () , 15 mg/i (V),

20 mg/i (§)

,

30 mg/i (0)

56
o

o

o

o

lO

o o o

o o o

o o o

^

CO CNJ (Ludd)oo

o o

o

o

57

igure

12.

CO

generation

from

flexible

polyurethane

foam

and

polyester

decomposed

along

and

together.

(Flaming,

525°C,

NBS

Toxicity

Test

Method)
5000

o

o

o

o

o o O O

o o o

o o o

CO CVi ^

(ludd)oo

58

Figure

13.

CO

generation

from

flexible

polyurethane

foam

and

polyester

decomposed

alone

and

together.

(Non-flaming,

375°C,

NBS

Toxicity

Test

Method)
APPENDIX A

The derivation of the equation describing the material concentration in the

animal exposure chamber assumes that:

• the pyrolysate generated in the combustion chamber is instantaneously

mixed throughout the volume of the combustion chamber. This is an approximation of experimental observations

;

• the pyrolysate concentration is not altered by loss of material to the

interior surfaces of the combustion chamber, exhaust duct, connecting

pipe, and animal exposure chamber. This is also an approximation, since

soot and tar deposits were observed in the connecting pipe and control

valve located between the exhaust duct and the animal exposure chamber.

The problem is divided into two parts. First, a solution is developed for the

material concentration in the combustion chamber. Second, an equation is

developed that describes the filling process of the exposure chamber from the

combustion chamber.

I. Combustion Chamber

The change of pyrolysate in the combustion chamber is given by:

dt ( 1 )

where

Cb

Yb

f(t)

the pyrolysate concentration, mg/i

the volume of the combustion chamber, i

the volumetric airflow through the combustion chamber, i/s

the generation rate of pyrolysate, mg/s

rewriting equation (1) as.

dC, V

b o dt V,b

f(t)

V,

( 2 )

one can solve this first order ordinary differential equation by multiplying by

exp (Vq t/Vjj ) . This leads to a solution of equations of the form.

59
dt + D exp (

t) (3)

V

Cfa - exp( - ^ t ) b

exp(

V, t)

f(t)

V,

V

o V

b

where D = an arbitrary constant determined by initial conditions.

For a given function of f (t)

,

the problem of determining a solution of equation

(2) is reduced to that of evaluating the antiderivative in equation (3) and the

application of initial conditions. Since the actual calculations that were performed assumed constant mass loss rate, equation (2) will be solved for f(t) = m, constant, using two different initial conditions, at time t = 0 and either

Cjj = 0 or Cjj ^ • Where is some initial concentration in the exposure

chamber

.

For fCt) - m

Substituting m for f (t) in equation (3)

,

the integral

exp(

V

f(t)

V, dt

. o . m , exp( — t) — dt

b b

(4)

Moving constants out of the integral and performing the integration yields

m

V, exp(V, t) dt = m

V,

V, exp(-

V

V, t) m

exp( n— t)

b

(5)

Equation (5) is substituted for the integral in equation (3)

.

Rearranging

terms yields

60
m

C + D exp( t) ( 6 ) b

V

o

V,

For initial conditions t = 0. =0

Applying initial conditions yields a value for the arbitrary constant of

(7)

Substituting equation (7) into equation (6) produces an exact solution for the

concentration of pyrolysate in the combustion chamber.

C

b

(1 - exp(- ( 8 )

For initial conditions t = 0. C^J =

Applying these initial conditions to equation (6) yields a different value for

the arbitrary constant of

D = - -

V

o

(9)

61
Substituting equation (9) into equation (6) produces the following exact

solution

m

(1 - exp (-

V

V,

V

t)) + exp (- — t) ( 10 )

II. Exposure Chamber Concentration

It was assumed that the animal exposure chamber was being filled at the

material concentration calculated for the combustion chamber. The change in

the concentration in the exposure chamber is then given by

dCe ^

g(t)

dt V b

( 11 )

where

C = the pyrolysate concentration in the exposure chamber, mg/£

V = the volume of the animal exposure chamber, i gft) = the volumetric flow rate between combustion chamber and

exposure chamber, £/s

Solving for the animal exposure chamber concentration yields

C

e

C, dt

b

( 12 )

If g(t) and V are constants, as they were in these experiments, equation (12)

is solved by lubstituting either equation (8) or (10) for Cj, and performing the

integration from t = 0, the start of exposure chamber filling to t - tj , the

end of the filling process:

62
C (13)

e

o

C, dt

b

where G = g(t) , a constant filling rate, i/s

Using equation (10) with equation (13)

,

C

e m

(1 - exp(-

V — o

V

-°t)) + exp(-

V

o

V, dt (14)

After performing the integration, this simplifies to

C

e V V

e o

Vo . mt^ + (1- exp(- ^ t^) (K^V^ - m — ) b V

o

(15)

63
FORM NBS-1 14A (REV.1 1-84)

U.S. DEPT. OF COMM,

BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

2. Performing Organ. Report No. 3. Publication Date NBSIR-86/3457 November 1986

4. TITLE AND SUBTITLE

Comparison of the Toxicity of the Combustion Products from a Flexible

Polyurethane Foam and a Polyester Fabric Evaluated Separately and Together by

the NBS Toxicity Test Method and a Cone Radiant Heater Toxicity Test Apparatus

C. Levin, Emil Braun, Joshua L. Gurman, Maya Paabo

6 . PERFORMING ORGANIZATION (If joint or other than NBS. see instructions) 7 . Contract/Grant No.

NATIONAL BUREAU OF STANDARDS

U.S. DEPARTMENT OF COMMERCE 8- Type of Report & Period Covered

GAITHERSBURG, MD 20899

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State. ZIP)

U. S. Consumer Product Safety Commission

Bethesda, MD 20207

10.

SUPPLEMENTARY NOTES

Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here) Representative specimens of flexible pol}rurethane foam and polyester fabric were thermally decomposed separately and together in order to compare the toxicity of the

combustion products from the combined materials with those from the single

homogeneous materials and to compare the toxicological results obtained with the NBS

Toxicity Test Method with those using a cone radiant heater toxicity test apparatus.

Gas concentrations (CO, CO2 , O2 and HCN) , blood carboxyhemoglobin , and LCjq values

in Fischer 344 rats were determined for the materials under both flaming and non- flaming conditions. With the NBS Toxicity Test Method, the results of the non- flaming combined experiments indicated that both materials contributed in an additive manner to the concentration of the combustion products. However, under

flaming conditions, the generation of HCN is greater than that predicted from the

addition of the maximum amounts produced by the materials separately. With the cone radiant heater under conditions designed to generate the maximum concentrations of

combustion products, animal deaths were observed in the combination experiments, but

not in the single material exposures. In the combined material testing with both

toxicity test systems, flaming conditions produced deaths during the 30 minute

exposures; whereas, non- flaming conditions produced deaths following the exposures.

Estimated LCjq values for the combined materials in the radiant furnace were not

greatly different from the calculated values obtained with the NBS Toxicity Test.

12.

KEY WORDS (S/x to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon i, combustion products; inhalation; lethal concentrations; Toxicity Test Methods; polyesters; polyurethane foams; radiant heat; toxicity; upholstered furniture.

13. AVAILABILITY 14. NO. OF

PRINTED PACES

Unlimited

Q] For Official Distribution. Do Not Release to NTIS

Order From Superintendent of Documents, U.S. Government Printing Office, Washington, DC

20402.

] Order From National Techn ical Information Service (NTIS), Springfield, VA 22161

70

15. Puce

f 1 1

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