NBSIR 75-966

Measurements and Observations

of the Toxicological Hazard of

Fire in A Metrorail Interior

Mock-Up

M. M. Birky, A. W. Coats, S. E. Alderson,

J. E. Brown and M. Paabo

Center for Fire Research

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

and

B. Pitt

Johns Hopkins University

School of Hygiene and Public Health

Baltimore, Md.

February 1976

Final Report

\

U S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

NBSIR 75-966

MEASUREMENTS AND OBSERVATIONS

OF THE TOXICOLOGICAL HAZARD OF

FIRE IN A METRORAIL INTERIOR

MOCK-UP

M. B. Birky, A. W. Coats, S. E. Alderson,

J. E. Brown and M. Paabo

Center for Fire Research

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

and

B. Pitt

Johns Hopkins University

School of Hygiene and Public Health

Baltimore, Md.

February 1976

Final Report

U.S. DEPARTMENT OF COMMERCE, Elliot L. Richardson, Secretary

James A. Baker, III, Under Secretary

Dr. Betsy Ancker-Johnson, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler. Acting Director

CONTENTS

Page

LIST OF FIGURES iv

Abstract 1

1. INTRODUCTION , 1

2. EXPERIMENTAL DESIGN 2

2.1. Description of Mock-up of Metrorail Car

Interior 2

2.2. Material Identification 2

2.3. Ignition Source 2

2.4. Animal Exposure and Gas Sampling 3

3. EXPERIMENTAL RESULTS 3

3.1. Analytical Measurements 3

3.2. Biological Measurements 4

3.3. Correlation of Analytical and Biological

Results 5

4. CONCLUSION 6

5. REFERENCES 7

iii
LIST OF FIGURES

Page

Figure 1. Metrorail Car Mock-up 10

Figure 2. Motorized Rotating Wheel 11

Figure 3. Metro Subway Test No. 5 - PVC over

Chlorinated Rubber Cushion 12

Figure 4. Metro Subway Test No. 6 - Self -Skinning

F.R. Polyurethane Seat & PVC-Acrylic Wall. 13

Figure 5. Metro Subway Test No. 7 - Cement-Asbestos

Board Seat & PVC-Acrylic Wall 14

Figure 6. Atmospheric HCN Levels for Metro Subway

Tests No. 6 and 7 ............ . 15

iv
MEASUREMENTS AND OBSERVATIONS OF THE TOXICOLOGICAL

HAZARD OF FIRE IN A METRORAIL INTERIOR MOCK-UP

M. M. Birky, A„ W. Coats, S. E. Alderson,

J. E. Brown, M. Paabo and B. Pitt 1

Abstract

Oxygen depletion, carbon monoxide, carbon dioxide, hydrogen chloride and hydrogen cyanide were

selected for measurement and identification in

Metrorail fire tests.

Male rats exposed to the combustion products

were examined for changes in blood chemistry, gross

pathology and loss of function. Hydrogen cyanide

and carbon monoxide levels in blood were elevated

and functional changes were noted.

Key words: Blood; carbon dioxide; carbon monoxide;

fire; hydrogen chloride; hydrogen cyanide; oxygen;

rats.

1. INTRODUCTION

The major cause of fire fatalities in the United States

is inhalation of smoke and toxic gases [1]2. In the past the

assessment of the toxicological hazard has been based on

chemical analyses of gaseous products and an optical attenuation measurement for determining the smoke hazard. Review

of the fire literature suggests that such an assessment is

inadequate to define the toxicological hazard [2] . Based on

this information, the only effective method for assessing

the inhalation hazard is to expose living organisms to the

combustion products and combine the biological information

with chemical analyses.

Johns Hopkins University, School of Hygiene and Public Health.

Except for the actual exposure of the animals to fire conditions, all animal work was done at Johns Hopkins School of

Hygiene and Public Health. All animal work, wherever done,

was carried out under the supervision of B. Pitt of the Johns

Hopkins University School of Hygiene and Public Health.

Numbers in brackets refer to the literature references listed

at the end of this paper.

1
Seven fire tests of a proposed Washington Metropolitan

Area Transit Authority Metrorail subway car mock-up interior

[3] were recently conducted to determine the fire hazard (s)

of the materials used in interior construction . These tests

were instrumented to measure smoke density, heat flux, tempera

ture and gas production. The test results have for the most

part, been reported by Braun [3]. In two of the seven tests,

animals were included to determine the toxicological hazard (s)

of the products of combustion. It is with the details of

these tests, No. 5 and 6, that this report is concerned.

Atmospheric data from test No. 7 is also included in order to

compare combustion product generation in the 3 tests.

2. EXPERIMENTAL DESIGN

2.1. Description of Mock-up of Metrorail Car Interior

The mock-up (fig. 1) consisted of wall and ceiling

sections and three seat frames, one of which was a lateral

single and the other two were transverse double seats. The

floor was carpeted and the seat cushions were varied from

test to test.

2.2. Material Identification

The basic materials that were utilized in fire tests

No. 5, 6, and 7 were identified by infrared spectroscopy.

X-ray fluorescence was used to identify the presence of those

elements which are generally found in fire retardant formulations (table 1, page 8). The X-ray fluorescence measurements were limited to the determinations of Bromine (Br)

,

Chlorine (CI) , Phosphorus (P) , and Antimony (Sb) . The identification of these elements, however, is not conclusive proof

of the presence of a fire retardant, as some of these elements

may be found in other additives or in the polymer itself. For

example, additives such as blowing agents may contain a halogen; therefore, caution must be used in interpreting the

presence of a halogen in a polymer as confirmation of the

inclusion of a fire retarding agent.

2.3. Ignition Source

The ignition sources and their locations in the Metrorail mock-up were as follows:

Test No. Source Location

5 454 g (16 oz) newspaper on aisle seat

6 43 g (1.5 oz) paper bag on aisle seat

7 908 g (32 oz) newspaper on wall seat
2.4. Animal Exposure and Gas Sampling

A three-inch exhaust line was used to transfer the combustion products from the fire area to a motorized revolving

cage which contained three Wistar male rats each weighing

approximately 260 grams (see fig. 2) . The rats were in separate compartments within the wheel, which rotated at 8 rpm.

Prior to the experiment the animals were trained to walk in

the wheel in two training sessions a day for five days, each

session of five minutes duration. The animals were trained

in order to observe any changes in their behavior during

exposure to the combustion products. An abdominal-aorta

cannula was surgically placed in one animal (each test) two

days prior to exposure to provide for the rapid removal of

blood samples for carboxyhemoglobin (COHb) determinations.

This animal was not trained to walk in the wheel prior to

exposure. Since a large blood sample was required for cyanide

determination, an animal was sacrificed for this purpose.

Sampling ports were installed just before the interface

of the three-inch transfer line at the animal exposure chamber.

Sampling for continuous analysis of CO, C0 2 , 0 2 , and HC1, and

intermittent sampling of HCN took place at these ports.

Carbon monoxide (CO), carbon dioxide (C0 2 )/ and oxygen

(0 2) concentrations were determined from the same sampling

stream. Non-dispersive infrared techniques were used for

measurement of CO and C0 2 , and a polarographic oxygen cell

was used for the measurement of 0 2. The results of these

measurements for experiments 5, 6, and 7 are shown in figures

3 , 4 , and 5

.

Hydrogen chloride (HC1) concentrations were determined

by collecting the combustion products in distilled water and

monitoring this solution with an ion-specific electrode. The

sampling rate was two liters per minute for the duration of

the experiment. No HC1 was detected in the atmosphere in

these experiments at the lower limit of detectability which

was 50 ppm. In experiment 5 (table 1) the seat was a PVCcovered chlorinated rubber. Since only the seat cushion and

cover were involved in the fire and the volume of the mock-up

was quite large, high concentrations of HC1 were not found.

In experiments 5 and 6 the wall did not get involved in the

fire, thus explaining the absence of HC1.

3. EXPERIMENTAL RESULTS

3.1. Analytical Measurements

3
In experiment 7, the wall was involved. However, the

concentration of HC1 did not reach the level detectable with

the apparatus. This was apparently due to the fact that the

experiment was terminated before substantial quantities of

the wall material had burned.

The atmosphere containing combustion products was also

sampled sequentially for hydrogen cyanide (HCN) . The products

were collected in 0.1 N sodium hydroxide at a sampling rate of

250 cc/min. The solution was analyzed for cyanide according

to a modification of the procedure reported by Valentour [4]

.

The results of these measurements are shown in figure 6. The

presence of atmospheric HCN was detected in experiments 6 and

7. No atmospheric HCN was detected in experiment 5. This

was due to the absence of nitrogen-containing polymers in the

fire. In experiment 6, the source of HCN is attributed to the

polyurethane seat cushion. In experiment 7, the HCN is due to

the acrylonitrile present in the PVC-acrylic wall section.

3.2. Biological Measurements

In order to assess the overall toxicological hazard from

a test fire in a Metrorail car, the gas measurements were

correlated with animal behavior and blood chemistry in two

of the tests. The animals were exposed for the entire time

of the experiments. In experiment 5, this was 13 minutes and

in experiment 6, this was 12 minutes.

Male Wistar rats (206 g) were used in all the exposures.

The rats exposed in experiment 5 showed no deviation from the

behavioral patterns exhibited during the pre-test training

sessions. The rats exposed in experiment 6 were obviously

incapacitated to some degree as their ability to walk in the

wheel was severely curtailed. Post-exposure blood samples

were taken at various time intervals following the cessation

of the tests, from which COHb measurements were made. These

data are summarized in table 2 (page 9) for rats No. 1 and 2

in each test. Rat No. 3 was returned to Johns Hopkins

University for short-term observation after each test. No

long-term observations were made.

Blood chemistry included COHb and cyanide determinations.

Carboxyhemoglobin determinations were done according to the

spectrometric technique developed by Small, et al. [5].

The analytical procedure for determining blood cyanide was a two-step procedure consisting of a microdif fusion technique

[6] for separating cyanide from the blood followed by gas

chromatographic determination of the cyanide [4] . In experiment 6, the blood sample was divided into 2 parts, each portion treated separately.

4
As noted in table 2, blood samples for cyanide and COHb

determinations were obtained 10 minutes post exposure in the

sacrificed animal. The rate of release of COHb from rats

has been measured by Packham [7] . His data suggested that

in 10 minutes the COHb will decrease about 20% if there is

no pulmonary damage.

The effect of the delay time on cyanide (CN) concentrations in the bio-system is more difficult to assess. Data

obtained by Pettigrew and Fell [8] on rats which were injected

with cyanide intraperitoneally , suggest that the half-life

of the cyanide was 15 to 2 0 minutes. These data should be

interpreted with caution because of the different method of

exposure. In any event, the actual blood cyanide level

immediately after exposure may have been somewhat higher

than reported.

3.3. Correlation of Analytical and Biological Results

In order to correlate the carbon monoxide measurements

with the COHb determinations, the CO measurements were approximated with an average value for a specified time period of

the test to give the same dose. In experiment No. 6 (fig. 4)

the CO concentration to which the rats were exposed was

approximately 200 ppm for a period of 5 minutes. This dosage

(product of concentration and time) has approximately the equivalent effect as the measured time dependent concentration.

Carboxyhemoglobin levels as a function of CO concentration

and time for rats were determined by Hofmann and Oettel [9].

According to their data, this approximated dosage should lead

to a COHb level of 5%. The measured level was 12%. This

difference can be attributed to the fact that Hofmann and

Oettel 's results were obtained on rats at rest as opposed to

forced exercise as in the fire experiments.

A literature search on the dosage of hydrogen cyanide,

administered to rats by inhalation that produces a given

toxicological effect, shows that various authors are not in

agreement. Moss et al . [10] report that the minimum lethal

atmospheric level of HCN is about 50 ppm. At this level,

incapacitation occurred in 3 minutes and death in 8 minutes.

No blood measurements were given. More recent data reported

by Lynch [11] yields a 5 minute LC 50 (lethal concentration for

50% of animals) of 720 ppm. Again no blood cyanide levels were

reported. A similar, unpublished study using rats, reports a

5 minute LC50 of 480 ppm with large variation in blood cyanide

measurements suggesting there is either a large variation in

blood levels from a given dose, or that the analytical results

were in error. In any event, correlation of the environmental

concentration of hydrogen cyanide in experiment 6 with blood

levels could not be made with any certainty at this time.

5
In test 6, the average cyanide level from measurements

on the two blood fractions was 0.14 pg/ml. This level is

considered sub-lethal; however, as indicated above, the relationship between atmospheric levels and blood levels in rats

has not been established.

4. CONCLUSION

The deviation from the learned behavior of the animals

in experiment 6, coupled with significant blood CO and CN

content is evidence that a toxicological hazard definitely

resulted from the combustion of the particular polyurethane

cushions used in fire test No. 6. The decreased capacity of

the animals to maintain their position in the rotating cage

confirms this conclusion. The hazard arose from the cushioning, rather than some other portion of the seat assembly, as

evidenced by the absence of similar observed effects in Tests

5 and 7.

6
5. REFERENCES

[1] Birky, M . M. , Review of Smoke and Toxic Gas Hazard in

Fire Environment, Paper presented at the University of

Edinburgh (Oct. 1975) .

[2] Zikria, B. A., Weston, G. C., Chodoff, M. and Ferrer,

M. M. , Smoke and Carbon Monoxide Poisoning in Fire

Victims, J. of Trauma, Vol. 12, No. 5, 641-646 (1972).

[3] Braun, E. , A Fire Hazard Evaluation of the Interior

of WMATA Metrorail Cars, Nat. Bur. Stand. (U.S.) NBSIR

75-971.

[4] Valentour, James C, Aggarawal, Va. and Sunshine,

Irving, Sensitive Gas Chromatographic Determination of

Cyanide, Analytical Chemistry, Vol. 46, No. 7, 924-

925 (1974).

[5] Small, K. A., Radford, E. P., Fragier, J. M.

,

Rodkey, F. L. and Collision, H. A., A Rapid Method for

Simultaneous Measurement of Carboxy and Methemoglobin

in Blood, J. Appl. Physiol., Vol. 31, 154-160 (1971).

[6] Feldstein, M. and Klendsho j , N. C, The Determination

of Cyanide in Biological Materials, J. Lab. Clin. Med.,

Vol. 44, 166 (1954)

.

[7] Packham, S. C, Behavior and Physiology: Tools for the

Assessment of Relative Toxicity, Paper presented at

17th National Cellular Plastics Conference on Safety

and the Product Liability (Nov. 18-20, 1974).

[8] Pettigrew, A. R. and Fell, G. S., Microdif fusion Method

for Estimation of Cyanide in Whole Blood and Its Application to the Study of Conversion of Cyanide to Thiocyanate, Clinical Chemistry, Vol. 19, No. 5, 466-491

(1973)

.

[9] Hofmann, H. T. and Oettel, H., Comparative Toxicity of

Thermal Decomposition Products, Modern Plastics,

Vol. 46, No. 10, 98-100 (1969).

[10] Moss, R. H. , Jackson, C. F. and Seiberlich, J., Toxicity

of Carbon Monoxide and Hydrogen Cyanide Mixtures, Arch.

Industrial Hygiene Occup. Med., Vol. 4, 53-64 (1951).

[11] Lynch, R. D. , On the Non-Existence of Synergism Between

Inhaled Hydrogen Cyanide and Carbon Monoxide, Fire

Research Note No. 1035 (May 1975).

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U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

I. PUBLIC ATION OK REPORT NO. NBSIR 75-966

2. dov'l Accession

No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

MEASUREMENTS AND OBSERVATIONS OF THE TOXICOLOGICAL

HAZARD OF FIRE IN A METRORAIL INTERIOR MOCK-UP

5. Publication Date February 1976

6. Performing Organization Code

7. author(S) M . Paabo, B. Pitt, M.M. Birky, A.W. Coats,

S.E. Alderson and J.E. Brown

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 491-1 677

11. Contract /Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Same as No. 9

13. Type of Report & Period Covered

Final Report

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

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

bibliography or literature survey, mention it here.) Oxygen depletion, carbon monoxide, carbon dioxide, hydrogen

chloride and hydrogen cyanide were selected for measurement and

identification in Metrorail fire tests.

Male rats exposed to the combustion products were examined

for changes in blood chemistry, gross pathology and loss of function,

Hydrogen cyanide and carbon monoxide levels in blood were elevated

and functional changes were noted.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons

)

Blood; carbon dioxide; carbon monoxide; cyanide;

fire; hydrogen chloride; hydrogen cyanide; oxygen; rats.

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