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. tvvr .U56 NO.85-3286 1986 I90U V19 V 19 C.1 V I NBS-P IMDoin 09-0^00

Toxicity of the Pyrolysis and

Combustion Products of

Poly(Vinyl Chlorides): A Literature

Assessment

Clayton Huggett

Barbara C. Levin

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Gaithersburg, MD 20899

April 1986

“QC

100

• U56

85-3286

1986

I in part by:

nsumer Product Safety Commission

a, MD 20207

C.3

NBSIR 85-3286

TOXICITY OF THE PYROLYSIS AND

COMBUSTION PRODUCTS OF

POLY(VINYL CHLORIDES): A LITERATURE

ASSESSMENT

Clayton Huggett

Barbara C. Levin

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Gaithersburg, MD 20899

April 1986

Sponsored in part by:

U.S. 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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TABLE OF CONTENTS

Page

List of Tables iv

Abstract 1

1. INTRODUCTION 2

2. PROPERTIES OF PVC 5

3. THERMAL DECOMPOSITION OF PVC 6

4. TOXICITY OF PVC PYROLYSIS AND COMBUSTION PRODUCTS 9

4.1 Laboratory Measurements of PVC Decomposition Product Toxicity .. 13

4.2 Comparison of the Post-Exposure Toxicity of PVC Decomposition

Products with that of HCZ 20

5. LARGE-SCALE FIRE EXPERIMENTS 21

6. PVC IN FIRES 23

7. CONCLUSIONS 25

8. ACKNOWLEDGMENTS 26

9. REFERENCES 26

-iii-
LIST OF TABLES

Page

Table 1. Compounds Identified in Pyrolysis and Thermooxidation

Products of Poly(Vinyl Chloride) and Some Vinyl

Copolymers 31

Table 2. Toxicity Measurements of Various PVC Materials and

PVC-Containing Products 33

Table 3. Dependence of PVC Smoldering Toxicity on Temperature of

Decomposition in the DIN Toxicity Test Method 34

Table 4. Toxicity of PVC Decomposition Products in the Presence

and Absence of Water 35

Table 5. Toxicity of Some PVC Materials 36

Table 6. Comparison of the Toxicities of a Fire Retarded and Non-Fire

Retarded PVC Floor Covering and Wall Covering 37

Table 7. Incapacitation Times After Exposure to Non-Flaming PVC

Decomposed via the NBS Toxicity Test Method 38

Table 8. Comparative Toxicities with the NBS Test Method 39

Table 9. NBS 10 Minute Test for Rapidly Acting Toxicants 40

Table 10. Toxicological Results from HCJl Exposures With and

Without CO 41

Table 11. Toxicological Results from HCi Exposures With and

Without a Water Mist 42

Table 12. A Comparison of HC£ Gas Toxicity and PVC Toxicity 43

-iv-
TOXICITY OF THE PYROLYSIS AND COMBUSTION PRODUCTS OF

POLY(VINYL CHLORIDES): A LITERATURE ASSESSMENT

Clayton Huggett* and Barbara C. Levin

Abstract

Poly(vinyl chlorides) (PVC) constitute a major class of synthetic

plastics. Many surveys of the voluminous literature have been performed.

This report reviews the literature published in English from 1969 through 1984

and endeavors to be more interpretive than comprehensive. PVC compounds, in

general, are among the more fire resistant common organic polymers, natural or

synthetic. The major products of thermal decomposition include hydrogen

chloride, benzene and unsaturated hydrocarbons. In the presence of oxygen,

carbon monoxide, carbon dioxide and water are included among the common

combustion products. The main toxic products from PVC fires are hydrogen

chloride (a sensory and pulmonary Irritant) and carbon monoxide (an

asphyxiant). The LC^q values calculated for a series of natural and synthetic

materials thermally decomposed according to the NBS toxicity test method

ranged from 0.045 to 57 mg/Jt in the flaming mode and from 0.045 to > 40 mg/il

in the non-flaming mode. The LC^q results for a PVC resin decomposed under

the same conditions were 17 mg/il in the flaming mode and 20 mg/il in the nonflaming mode. These results indicate that PVC decomposition products are not

extremely toxic when compared to those from other common building materials.

When the combustion toxicity (based on their HCil content) of PVC materials is

compared to pure HC£ experiments, it appears that much of the post-exposure

toxicity can be explained by the HCil that is generated.

*The initial draft of this review was written by C. Huggett prior to his

retirement from the National Bureau of Standards.

- 1 -
Keywords: carbon monoxide, combustion products, hydrochloric acid,

large-scale fire tests, pol3rvinyl chloride, pyrolysis products, small-scale

fire tests, toxicity.

1 . INTRODUCTION

Poly(vinyl chlorides) (PVC) constitute a major class of synthetic

plastics and are used in a wide variety of industrial and household products.

Approximately seven billion pounds of PVC resins were produced in the United

States in 1984 [1]^. More than half of this amount, which corresponds to an

average of about thirty pounds per person, is used in building products,

including pipe and fittings, flooring, siding, and a wide variety of other

construction products [2]. Much of this goes into residential construction.

Other major uses include packaging, electrical insulation for wire and cable,

interior furnishings, and a host of miscellaneous household products. Because

of its ubiquitous presence in the built environment, PVC is a possible source

of fuel in unwanted fires. In a number of fires, injuries to firemen and

building occupants have been attributed to its thermal decomposition or

combustion products [3,4,5]. This, together with PVC's wide distribution, has

led to numerous studies of the nature of the products, their occurrence in

fires, and their physiological effects on living organisms.

A number of surveys of this voluminous literature have been performed.

One of the early surveys was performed at the Underwriters' Laboratories in

1963 [6]. An extensive survey was made by Tewarson at Factory Mutual in

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

this report.

-2 -
1975-76 in which he cited 262 references [7,8,9]. In a supplement prepared in

1979, he cites an additional 56 references [10]. The literature has increased

in volume at an accelerated pace since that time. Barrow, in his Ph.D thesis,

provides an excellent review of the toxicity of the thermal decomposition

products of PVC, with emphasis on experimental methods and physiological

effects [11]. Boettner and Ball reviewed work on the composition of the

volatile combustion products of PVC in 1981 [12]. Kent and van der Voort

described the behavior of PVC in fires in 1981 [13]. Recently, Hinderer has

reviewed the combustion product toxicity of PVC [14],

Despite this volume of publications, it is difficult to obtain a clear

picture of the role of PVC in fires. Reported data are difficult to compare

and sometimes contradictory. A number of reasons may be cited for this

difficulty:

1. Pure PVC homopolymer (PVC resin) is almost never encountered outside

the research laboratory. Most useful products are made from compositions compounded with a variety of additives designed to improve

their properties. These additives include polymerization catalysts,

plasticizers, lubricants, heat and light stabilizers, fire and smoke

retardants, fillers and reinforcing agents [15]. The amount of

plasticizer may vary from 10 parts per hundred of resin (phr) in

semi-rigid PVC*s to 100 phr in very flexible PVC's. Any of these

additives can affect the fire properties of the material and the

composition of its combustion products. It is rare that two investigators use what can be identified as the same formulation. Often the

samples are not adequately identified and, in some cases, the

formulation may not be known to the investigators.

-3 -
2. Methods of thermal decomposition or combustion of the samples vary

widely from one study to another, particularly with respect to the

thermal and atmospheric environment. These differences will affect

the rate of product formation as well as the composition and concentrations of the combustion products.

3. In those cases where animals have been used to assess the physiological effects of the thermal degradation products, a variety of

species, which may differ in their response to this exposure, have

been employed. Even when the same species and strain is used in

different studies, variations in the conditions of exposure can lead

to differences in response.

4. A plethora of methods for measuring responses to exposure have been

employed. Different end points have been used, different parameters

to characterize the experimental system are reported, and the results

may be given in different and frequently non-comparable units.

Despite these difficulties, a fairly coherent picture of the fire

behavior of PVC emerges from this mass of material. Minor inconsistencies may

be attributed to one or more of the factors listed above. The present review

concentrates on the more recent work (since 1969) and endeavors to be interpretive rather than comprehensive.

-4 -
2. PROPERTIES OF PVC

Poly( vinyl chlorides) are high molecular weight poljnners formed by the

free radical polymerization of vinyl chloride monomers.

n CH^=CHC£ -> (CH„-CHCJl)

2 Z n

The homopolymer contains 56.7% chlorine by weight. The structure is primarily

the linear head-to-tail configuration but various irregularities can occur in

the chain structure. The ends of the polymer chain may be occupied by a

number of different catalyst fragments and chain transfer agents. Typical

number average molecular weights lie in the range of 50,000 to 120,000.

The PVC homopolymer (PVC resin) is a hard, tough material that has little

practical application. It has poor stability when exposed to heat and light

and must be compounded with stabilizers to make it useful. These stabilizers

are often compounds of heavy metals, e.g., barium, tin, cadmium, and lead.

Rigid PVC, with a minimum of additives, may contain on the order of 90% PVC

homopolymer. It is used for pipes, ducts, building panels, siding, floor

coverings, and other building applications.

The PVC resin can be compounded with a variety of plasticizers, usually

high molecular weight organic esters, to give products the improved flexibility needed for use in films, tubing, wiring insulation, and the like.

Di-2-ethylhexyl phthalate (di-octyl phthalate, DOP) is perhaps the most

widely used plasticizer, but a great variety of other compounds are also used

-5 -
to impart special properties. Phosphate esters, such as tri-cresyl phosphate,

are sometimes used as plasticizers to avoid the increase in flammability

caused by phthalate and other purely organic plasticizers [16].

Rigid PVC has an oxygen index of greater than 40 [16]. The addition of

large amounts of plasticizer may lower this value to about 20 or 25. Fire

retardants containing bromine, antimony, or phosphorus compounds may be added

to counteract this effect. PVC compounds in general are among the more fire

resistant common organic pol3miers, natural or synthetic.

In addition to PVC composites, a number of other chlorine containing

polymers can be expected to show some similarity to PVC in their thermal

decomposition properties and the toxicological properties of their combustion

products. These materials will include vinyl chloride copolymers, poly-

(vlnylidene chloride), polychloroprene (neoprene), chlorinated polyethylene

and chlorinated PVC.

3. THERMAL DECOMPOSITION OF PVC

It is to be expected that the thermal decomposition or combustion

properties and the composition of the products from commercial items identified as "PVC" will vary widely depending on the nature and amount of additives

contained in the formulation. Nevertheless, a certain consistency of behavior

can be discerned if one focuses on the properties of the PVC homopolymer and

considers the further effects of additives on this basic behavior.

- 6 -
PVC horaopolymer has relatively poor thermal stability, beginning to lose

hydrogen chloride (HCi) slowly in the neighborhood of 100°C. The reaction is

believed to start at imperfections in the polymer chain. Tertiary chlorine

atoms, allylic chlorides and various oxygenated structures have been suggested

[17]. The reaction appears to be weakly autocatalytic. Thermal stabilizers

react preferentially with the weak points in the polymer chain, preventing

development of the autocatalytic process. Through the use of stabilizers,

useful service temperatures can be achieved.

The pyrolysis and oxidation of PVC have been studied by a number of

investigators. Woolley [18] and O’Mara [19] have given the most detailed

accounts and have summarized earlier work. The reported results depend on the

particular formulation used and close agreement is not to be expected between

investigators. However, a fairly consistent pattern of behavior emerges.

Stabilized PVC resins begin to lose HCJl slowly when heated to about 200°C.

The rate of HCi evolution increases with temperature, becoming fairly rapid at

230°C. By 300°C, the dehydrochlorination is very rapid and results in an

almost quantitative evolution of HCA. Woolley reports activation energies for

the dehydrochlorination reaction of 174 kJ/mol and 151 kJ/mol in nitrogen and

air, respectively, indicating the rapid increase of reaction rate with

temperature

The evolution of HC^. results in unsaturation in the polymer chain. The

dehydrochlorination appears to progress in stepwise fashion along the polymer

chain to produce conjugated unsaturation. This leads to color formation in

the residue and cyclization reactions producing benzene and related compounds.

Both Michal [20] and Woolley [21] found about 70 compounds among the thermal

-7 -
decomposition products of PVC resin. Table 1 lists those products identified

by Michal from PVC and some vinyl copolymers. Among those identified were

aromatic hydrocarbons, unsaturated hydrocarbons, and chlorine-containing

compounds. Benzene was the most prevalent organic product, amounting to

several percent of the original sample weight [19,21]. Others were present in

much smaller amounts.

Lat timer and Kroenke [22] have shown by isotopic labeling experiments

that the benzene and other conjugated species result from intramolecular

cyclization, while the mixed aromatic-aliphatic compounds, such as toluene

involve intermolecular reactions. Only small amounts of the vinyl chloride

monomer and other chlorine-containing organic compounds are found.

In the presence of oxygen, the decomposition is somewhat accelerated but

primary products are little affected. Carbon dioxide (CO2 ), carbon monoxide

(CO) and water are formed from the dehydrochlorinated residue, particularly at

high temperatures, thus decreasing the yield of organic products. Oxygenated

organics are not found in significant amounts [21].

The presence of plasticizers and other additives will give additional

products characteristic of the additives. There appears to be little interaction between the PVC and the plasticizer. O'Mara suggests that gas chromatography/mass spectrometry (GC/MS) "fingerprints" of plastisols can be used to

identify the plasticizers [19]. Inorganic fillers capable of reacting with

HCJl, such as CaC02 , can reduce the amount of HCJ, evolved [23]. Other

inorganic additives, such as molybdenum compounds, have been promoted as smoke

reducing compounds. Presumably, they catalyze the oxidation of particulates.

-8-
The presence of phosgene among the combustion products of PVC has been

investigated because of its well known toxic properties. Woolley [21] was

unable to confirm the presence of the compound among the thermal decomposition

products of PVC in air. Brown and Birky [24] made a careful search for

phosgene using a variety of decomposition conditions. Under most conditions,

only trace amounts (0.01 to 0.16 mg/g) of phosgene were detected, however,

greater quantities (up to 1 .6 mg/g) were formed when decomposition occurred as

a result of electrical arcing.

Burning PVC can produce large amounts of particulate matter. The actual

amount will depend on the conditions of combustion, particularly the oxygen

supply, and the presence of other fuels. HCZ may be adsorbed on the particulates and be transported in that manner [25]. HCil may also be condensed by

moist air to form a corrosive hydrochloric acid mist. This mist and smoke can

obscure vision, thus interfering with escape and rescue. The pulmonary damage

from PVC smoke inhalation has been shown to be more severe than that from

HC£ alone probably because the particulates may be drawn into and deposited in

the lungs where the adsorbed or dissolved HCZ enhances the toxic effect [54] .

On the other hand, the potential exists that a water spray applied to the fire

gases may remove some of the HCJl [26] .

4. TOXICITY OF PVC PYROLYSIS AND COMBUSTION PRODUCTS

Many studies of the toxicity of PVC combustion products have been

performed. A recent review by Hinderer [14] presents a summary of the

findings. Again, the drawing of quantitative conclusions is made difficult by

variations and uncertainties in the materials tested, differences in proce-

- 9-
dure, and dissimilar ways of presenting the results. Nevertheless, it is

possible to form a useful qualitative picture of the toxicological behavior of

PVC in fires.

According to the literature discussed in detail below, the acute

inhalation toxicity during and following exposures to PVC thermal degradation

products appears to be due almost entirely to the presence of CO and HC2.. The

chronic effects of multiple exposures to PVC thermal decomposition products

have only been examined in a few cases and are not well understood [27].

Additives contained in PVC compositions and other fuels that accompany PVC may

produce other toxic products. For example, an experimental PVC composition

containing zinc ferrocyanide was shown to produce a rapidly acting toxic

combustion atmosphere [28] . This effect was probably due to hydrogen cyanide

(HCN) which formed by a reaction of HC£. with the ferrocyanide (Table 9).

Since carbon monoxide and hydrogen chloride exert their physiological

effects through different mechanisms, direct interaction between them is not

expected and the assessment of their individual roles in casualty production

is difficult. Carbon monoxide is an asphyxiant causing incapacitation and

death primarily during exposure. HCJl, on the other hand, is both a sensory

and pulmonary irritant. As a sensory irritant in the upper respiratory

tract, HCil can depress the respiration rate, thus slowing the ingestion of

CO. The sensory effect is rapid and concentration-dependent [11,54]. HC2. can

also act as a pulmonary irritant, causing severe damage to the lower respiratory tract and post-exposure death [54].

- 10 -
Hydrogen chloride is extremely soluble in aqueous body fluids.

Therefore, much HCi is removed from the inhaled gases in the nose and upper

respiratory passages. This occurrence affords some protection against

pulmonary damage. Rats and mice, used in most experiments, are obligatory

nose breathers. Humans, on the other hand, when confronted with a sensory

irritant, tend to bypass the nasal passages by breathing through the mouth.

Some investigators have thus predicted that pulmonary damage from HCJl would be

much more severe in humans than in rodents [29].

Alarie and his coworkers examined the effects in mice exposed to

HCJl or PVC decomposition products both by normal breathing and through a

tracheal cannula that delivered the gases directly to the lungs. They found

the PVC LL^q (30 min exposure plus 3 hour post-exposure period) to be about

seven times greater for the nose breathing mice than for the cannulated mice

[30]. The HC^. LC^q (10 min exposure plus 3 hour post-exposure period) values

for mice with and without tracheal cannulas were 1100 and 10100 ppm,

respectively. From these results, they postulate that the acute lethality of

materials that produce water soluble acid gases will be underestimated by

experiments with small rodents and that the actual toxicity to humans will be

underestimated by this ratio.

2 LC^q is defined by Alarie as the mass of tested material which when thermally

decomposed via the University of Pittsburgh test method causes 50% of the

animals to die in the specified exposure time plus a short post-exposure observation period; however, in combustion studies, LC which stands for lethal

concentration is usually defined as the mass of tested material divided by the

available volume of the combustion products or the concentration of a specific

gas. Therefore, for the purposes of this report, the results of these experiments will be presented as LL^q indicating that a lethal loading of material is

the figure of merit.

- 11 -
Work by Kaplan et al. [31] using juvenile baboons, which like humans may

breathe through their mouths, does not support this conjecture. They showed

the lethal amount of HCil to be about the same for baboons (5 min at 16600 ppm)

and nose-breathing rats (5 min at 15200 ppm). These deaths were postexposure. Moreover, exposure to high concentrations (baboon: 17300 ppm;

rat: 77000 ppm) of this sensory irritant for 5 min did not incapacitate

either animal, as measured by an escape task.

Barrow et al. [32] have made extensive studies of the irritant effects of

inhaled gases including HCil and the total thermal decomposition products of

PVC . Both caused a reduction in respiration rate. The maximum percent

decrease in the respiration rate was found to be a linear function of the log

of the concentration over a considerable range of concentrations of the

irritant gas. They define the RD

5 Q as the concentration of gas necessary to

cause a 50% decrease in the respiratory rate from that of the animal prior to

exposure. Since pulmonary irritants, in contrast to sensory irritants,

increase the respiratory rate while decreasing the tidal volume, it can be

judged that PVC products act more like sensory than like pulmonary irritants.

The decomposition products of PVC were reported to be somewhat more potent

than pure HCi. Unfortunately, the method of exposure in the two cases was

different so no quantitative comparison is possible. The RD

5 Q depends on the

maximum concentration of products in a flowing air stream rather than the

total amount. The PVC samples were decomposed in a ramp-heated furnace where

the concentration of decomposition products varied with time and no determination of the maximum concentration was made. Experimental details, including

extensive observations of physiological and pathological effects, are given in

a thesis by Barrow [11]. Mice and rabbits were used; some of the rabbits had

- 12 -
tracheal cannulas to study pulmonary irritants. The extensive damage noted in

the upper and lower respiratory tract 24 hours following exposures was similar

for both HCil and the PVC decomposition products. At high concentrations, eye

damage resulted.

Wong et al. [33] have examined the long term pulmonary performance of

guinea pigs following 30 min acute inhalation exposures to different concentrations of PVC thermal decomposition products. They used a nonlntrusive and

noninvasive method in which the animals are exposed to the toxic combustion

products and then challenged with a mixture of 10% CO

2

, 20% ©2 and 70% N

2

. In

control animals, this mixture will increase both tidal volume and respiratory

rate. In the exposed animals, these responses are depressed - an indication

of pulmonary damage. The gradual return to normal indicates the recovery of

the animals. Wong et al. found that only the group exposed to the greatest

amount of combustion products from PVC (10 grams or ~ 16 mg/il) still showed

lowered pulmonary performance 57 days following the exposure. Animals exposed

to lower concentrations recovered prior to that time.

4.1 Laboratory Measurements of PVC Decomposition Product Toxicity

Cornish and Abar [34] were among the first to investigate the toxicity of

PVC decomposition products. They used a flow system with a temperature slowly

rising (3°C/min) to a maximum of 550°C. The air flow was 2.8 Jl»min ^ and the

exposure chamber (a dessicator) volume was 7 Jl so the products were quickly

swept through and out of the chamber where 4 rats were exposed for approximately 140 minutes or until death. They were observed for 24 hours following

the exposure. The results of these studies on seven different PVC samples are

- 13 -
shown in Table 2. The samples identified as pure homopolymers of PVC were

more toxic on a sample mass basis. Carbon monoxide appeared to be a factor in

causing lethality, but the data were inconsistent.

In a later study, Cornish et al. [35] compared results obtained in their

dynamic system (rising temperature of 3°C/min until a maximum of 800°C was

reached; five animals were exposed for 140 min and observed for 7 days;

airflow was 3 Jl/min) to those obtained in a 1500 I static system during a 4

hour exposure of 15 rats (temperature reached in 1-2 min; material exposed for

6-10 min). The observed LC^q values were 4 mg/

in the dynamic system and

36 mg/

in the static system.

At about the same time, Hofmann and Oettel [36] and later Hofmann and

Sand [37] studied the toxicity of PVC decomposition products. They subjected

rats to the products from a rigid PVC (5 g samples) decomposed in the DIN

toxicity test furnace at a series of fixed temperatures. This apparatus

supplies an approximately constant concentration of decomposition products to

a flowing air stream (100 Jl/hr) during a 30 minute exposure period. The mass

loading density was 50 mg/£., and in the later experiments 20 mg/i and 10 mg/l

due to subsequent air dilutions. The expected variation of toxicity with

temperature (Table 3) was observed and correlated with the decomposition

temperature of the polymer. For a mass loading of 50 rag/i, no fatalities

occurred from exposure to the products generated at 200°C, but 10 of 12

animals died when PVC was decomposed at 300°C. Deaths were reported during

the 30 minute exposure, but no post-exposure observations were taken. Since

PVC decomposition products have been found, in other methods, to produce many

post-exposure deaths of animals that survive the exposure, we can assume that

- 14 -
the specimens would have been found to be much more toxic if the animals that

survived the exposure had been observed post-exposure. The carboxyhemoglobin

content of the blood in the dead animals was below the lethal level expected

for pure CO, an indication of the presence of toxicants in addition to CO.

Kishitani [38] studied the toxicity of smoke from 30 grams of a rigid PVC

board to mice. The material was decomposed at temperatures rising from

ambient to 740°C in 15 min. Two liters per min of the smoke flowed through

the 56 I exposure chamber in which one mouse was exposed for 15 min. Five

tests were run on each material. It is difficult to make a quantitative

interpretation of his data. All the animals died during or immediately

following the 15 min exposure. COHb levels ranged from 13-30%. Kishitani and

Nakamura [39] made a more detailed study in 1974, but, again, quantitative

evaluation of their results is difficult. They noted that all surviving

animals died within 24 hours following the exposures. Rapid decay of the HCJl

concentration was noted. However, they believed that at 350°C, the toxicity

was mainly due to HCA and that at 500°C and above, it was due to CO and HCJl.

Kishitani and Yusa [40] attempted to determine the relative toxicities of the

thermal decomposition products of various building materials by observing the

exposure time necessary to cause the collapse of mice placed in rotating

cages. Post-exposure deaths were noted. Based on times-to-collapse , comparison of a series of materials, which included five different types of wood, two

melamine-resin sheets, a polyacrylonitrile, a polyamide, a wool, a urea resin

foam, a polystyrene foam, and a polyurethane foam, showed a rigid PVC foam to

be of medium toxicity and a PVC flexible sheet to be the least toxic.

- 15 -
Boudene et al. [26] determined the effects of water solubility on the

toxicity of PVC decomposition products. They used a traveling furnace in a

flow system similar to the DIN system but with the furnace travel cocurrent

with the air flow (Table 4). Rabbits were exposed for 30 minutes including a

4 hour post-exposure period. When the products of PVC decomposition were

passed through a water bubbler before entering the exposure chamber, the

toxicity was decreased 5 to 6 times, presumably because the HCJl was removed by

dissolution in the water. Lethal concentration (LC^q values) of HCJl for

rabbit was calculated to be 12500 ppm for a 30 min exposure. HC£. rarely

caused the rabbits to die during the exposure; deaths were usually noted after

very long delays, sometimes as long as a month. The thermal decomposition

products of PVC, like HCil, caused post-exposure deaths, sometimes after 15

days

Hilado and Crane [41] attempted to compare toxicity results obtained with

the USF/NASA and FAA/CAMI methods for a variety of polymers. The USF/NASA

method exposes 4 mice in a 4.2 I chamber to the decomposition products from

1 g samples heated at 40°C/min from 200 to 800°C, while the CAMI method

exposes 3 rats in a 12.6 I chamber to the decomposition products from 1 g

samples heated at 600°C. If all the material decomposed, then the test

animals would have been exposed to a nominal concentration of 240 mg/2, in the

USF test and 80 mg/2, in the CAMI test. Time to death for a PVC specimen was

16.4 min in the USF/NASA test and 15.3 min in the FAA/CAMI test. Time to

incapacitation was 6 min in the USF/NASA method and 11.9 min in the FAA/CAMI

method. No post-exposure observations were made.

- 16 -
Alarie and Anderson [42] give results for a 92% PVC resin which showed an

LL^q of 7.0 g for a 30 minute exposure plus a 10 minute post-exposure period.

A plasticized formulation containing 46% homopolymer showed a correspondingly

lower toxicity with an LL^q of 15.2 g. A 92% PVC resin containing 5% zinc

ferrocyanide produced an LL^q of 2.3 g. Assuming all the material decomposed

and the combustion products are diluted by 600 I of air in this flow-through

dynamic system, the nominal 30 minute LC^q values would be 11.7, 25.3, and

3.8 tag/

for the three formulations, respectively. In Alarie 's classification

scheme, the first two PVC materials fall into the more toxic than wood class,

whereas PVC with zinc ferrocyanide is considered much more toxic than wood.

The increased toxicity of the last material is presumably due to the high

concentration of HCN that is generated.

In the process of comparing the University of Pittsburgh's test method

and the NBS test method, Anderson et al. [43] examined a number of PVC

materials. The Pittsburgh test method was modified to include a 14 day postexposure period. The LC^q values are given in Table 5.

Herpol [44] used the DIN method to compare a number of fire retarded and

non-fire retarded materials including some containing PVC. Rats were exposed

for 30 minutes to the decomposition products of a PVC floor covering and a

wall covering heated at three different temperatures, 500, 600, and 700°C. In

all cases, 10 grams of material was placed in the furnace. The results for

the fire retarded and non-fire retarded PVC materials are shown in Table 6.

From these results, it appears that the fire retarded PVC's were more toxic

than the non-fire retarded materials at 500°C (where the materials did not

flame). At 600 and 700°C, the toxicities were about equal. In many cases,

- 17 -
the CO and COHb levels seemed high enough to account for the deaths. Since

there were no post-exposure observations, the toxicity due to the HCi from the

PVC is probably underestimated.

Levin et al. [28] decomposed a PVC resin according to the NBS toxicity

test method. They were not able to calculate within-exposure LC^q values

since only one rat died during the 30 minute exposures to either the flaming

or non-flaming decomposition products at the highest concentrations tested.

However, with a 14 day post-exposure observation period, LC^q values of 17.3

and 20.0 mg/il were determined for flaming and non-flaming conditions,

respectively. With this same PVC, they also examined the incapacitation times

of the rats who were instrumented to perform the hind-limb flexion conditioned

avoidance response. Exposures continued until all animals were incapacitated

as indicated by no longer responding to an electrical shock (Table 7). At a

concentration of 30.9 mg/i, the mean incapacitation time was 45 minutes (range

from 9 to 86). At a higher concentration (46 mg/Jl), the mean incapacitation

time was 36 minutes (range from 12 to 46).

Toxicological studies performed at NBS on CO in air indicated that

4600 ppm of CO were necessary to cause 50% of the rats to die during the 30

minute exposures [53]. No deaths occurred following these CO exposures. In

PVC experiments [28], the highest concentrations (averaged over 30 minutes) of

CO were 900 ppm in the non-flaming mode and 2300 ppm in the flaming mode. In

both modes, these CO concentrations by themselves would not be sufficient to

cause deaths. However, other studies at NBS have shown that in the presence

of CO

2

, the lethal CO level decreases such that at 5% CO2, 2500 ppm of CO

becomes lethal [53]. PVC, in the flaming mode at the highest concentration

- 18-
tested (30 mg/£), produced an average concentration of 2300 ppm of CO and

12,800 ppm of CO

2

• This implies that at only slightly increased sample

masses (~ 1.5 times), within-exposure deaths due to CO and CO 2 alone could

have occurred. In the non-flaming mode, the levels of CO and CO

2 were not

sufficient to produce within-exposure deaths. The sample loading would have

had to be increased 4-fold before the concentrations of CO and CO

2 would be

lethal. HCil, on the other hand, produces post-exposure deaths and is probably

largely responsible for those deaths. These data emphasize the importance of

a post-test observation period for materials producing irritant gases.

These PVC results are compared to those from a variety of materials in

Table 8 [28]. According to the test method developed at the National Bureau

of Standards, the LC^g values of these natural and synthetic materials ranged

from 0.045 to 57 mg/

in the flaming mode and 0.045 to > 40 mg/

in the nonflaming mode. Thus, PVC decomposition products do not appear to be extremely

toxic compared to those from other common building materials.

According to Table 8, even PVC containing zinc f errocyanide, a smoke

suppressant, does not appear to be extremely toxic. However, in the NBS

toxicity test method, materials with LC^g values between 2 mg/£ and 30 mg/

should be tested to determine if they rapidly produce concentrations of

combustion products that will cause death from very brief exposures (i.e., 10

min). Deaths that occur within a 14 day post-exposure period are counted.

This test was performed for both the PVC and the same formulation with zinc

ferrocyanide. The results are given in Table 9 and indicate that the PVC plus

zinc ferrocyanide is a very rapidly acting toxicant. All of the animals were

incapacitated in the 10 minutes and all died either during or post-exposure.

- 19 -
The high concentrations of HCN that were generated from PVC with zinc ferrocyanide are also noted in Table 9.

4.2 Comparison of the Post-Exposure Toxicity of PVC

Decomposition Products With That of HCJl

If HCil were the principal toxic product responsible for the deaths

following exposure to PVC thermal decomposition products and if that decomposition gave a nearly quantitative yield of HCJl, we would expect good agreement

between the properly weighted toxicity of PVC decomposition products and that

of pure HCJl gas. To make this comparison, the toxicity data on HCJl need to be

examined first.

Higgins et al. [45] give data on the effects of 5 minute exposures of

rats and mice to HCJl gas followed by a seven day observation period. They

also investigated the additional effect of exposures to CO (concentrations

tested were calculated to produce 25% carboxyhemoglobin levels) on HCJl

toxicity. Their results are given in Table 10. The difference in LC^q values

between exposure to HCJl with and without CO at this sub-lethal level was not

statistically significant, supporting the position that HCJl and CO react by

independent physiological mechanisms.

In related work by Darmer et al. [46], rats and mice were exposed to HCJl

vapors and water saturated aerosols for periods of 5 and 30 minutes and

observed for 7 days. Rats were found to be considerably more resistant to HCJl

vapors than mice. The five minute LC^q values for the rats and mice were

41000 and 13700 ppm and the 30 minute LC^q values were 4700 and 2600 ppm,

respectively (Table 11). No rats died during the 5 minute exposures, although

-20-
some mice died at the two highest concentrations (26000 and 30000 ppm). In

the 30 minute exposures, deaths during the exposures were noted at 27000 ppm

and above. Exposures to the HCJl aerosols did not significantly affect the

toxicity. Rabbits and guinea pigs showed a degree of susceptibility to HC£.

similar to that of mice. In summary, the HCii LC^q value for 5 minute

exposures range from ~ 11000 to 41000 ppm and the 30 minute LC^q values range

from 2100 to 5700 ppm. These include post-exposure deaths.

Since the toxicity of HCil occurs primarily following exposures, data from

some of the better characterized experiments on the toxicity of PVC decomposition products and which include post-exposure observations are compared to

those for HCil gas in Table 12. For this table, it is assumed that PVC gives a

quantitative yield of HCi. (58.3% HC£ by weight); additives and fillers are not

considered. With the exception of C-PVC pipe, the results Indicate that the

post-exposure toxicity of the thermal decomposition products of PVC can be

explained based largely on their HCJl content. The agreement is close enough

that there is no reason to hypothesize the need for other potent toxicants in

significant quantities to explain the toxicological results.

5. LARGE-SCALE FIRE EXPERIMENTS

The problem of relating results obtained in a small-scale laboratory

apparatus to conditions in a real fire is a universal one in fire research and

particularly critical in combustion toxicology. The problem is particularly

difficult in the case of PVC for two reasons. First, PVC is among the more

fire resistant of commonly encountered fuels. It does not burn readily by

itself and usually requires a vigorous fire involving more combustible fuels

-21 -
to bring about its thermal decomposition. The products from these combustible

fuels, usually including substantial amounts of CO, mix with the products from

the PVC and may be responsible for much of the toxic effects observed.

Second, the HC£ in the smoke can behave not as an inert mixture when the smoke

moves away from the fire source, showing, instead, condensation on and

settling out with particulate matter, adsorption on surfaces, and dissolving

in water droplets [47]. Consequently, the exposure to smoke that has traveled

some distance in a building fire may be quite different from that received in

a close-coupled laboratory system.

In an effort to obtain a better understanding of the problem, a number of

investigators burned PVC in large-scale experiments simulating real fire

scenarios. Stark et al. [48] were among the first to carry out such experiments at the Fire Research Station in 1969. They burned cellulosic fuels in a

small compartment with PVC wall lining or with strips of rigid PVC. With

complete combustion of the PVC, the HCZ was equivalent to the chlorine

content. They concluded that the solid PVC would contribute a significant

amount of HC^. to the fire gases but that PVC wall paper would not be likely to

contribute much to the toxicity due to the small quantity of PVC material

compared to the amount of other furnishings.

Packham and Crawford [49] thermally decomposed electrical nonmetallic

tubing (ENT) made from rigid PVC and studied the toxicity in both small-scale

and large-scale experimental conditions. In the small-scale tests, the NBS

toxicity test method was utilized to decompose the materials in the nonflaming mode. The resultant hC^Q value was 28.5 mg/Z,; all lethalities were

post-exposure. In the large-scale tests, samples were decomposed in a closed

-22 -
\ 2 21.7 room, using either a 2.2 kg wood crib or a radiant flux of 25 kW/m to

decompose the ENT. In the experiments with wood cribs, they concluded that

high temperatures and CO from the cribs posed a greater threat than the HCJl.

In the radiant heating experiments, significant concentrations of PVC decomposition products were found, but animal fatalities were still considered to

result from heat stress rather than smoke inhalation. HCi. recoveries ranged

from 23 to 50% of the theoretical in the large-scale tests; whereas in the

small-scale tests, 64 to 96% of the theoretical yield was generated.

In none of these tests was a quantitative full-scale/bench-scale

correlation obtained.

6. PVC IN FIRES

Because of the wide occurrence of PVC in buildings and residences, it is

to be expected that PVC will be present in many accidental fires. Since the

decomposition products are usually accompanied by large quantities of combustion products from other fuels, it is difficult to judge their contribution to

the toxic threat. Post-exposure analytical studies of fire victims are of

little help since chloride ion, the most characteristic PVC product, is a

common constituent of all body fluids. Casualties attributed to "smoke

inhalation" are frequently blamed on PVC although there may be little direct

evidence of its having played a significant role. For example, the Beverly

Hills Supper Club fire is frequently cited as a fire where PVC contributed

significantly to injury and loss of life, yet the amount of PVC involved was

small compared to the amount of other fuels capable of producing toxic combustion products [3 ]

-23 -
Lowry et al. [50] analyzed gas samples from 72 residential fires in the

Dallas area. Hydrogen chloride was found in 9% of the samples, with an

average concentration of 1.1 ppm and a maximum concentration of 40 ppm. Of

the gases examined, CO was the principal toxic gas found.

A small number of fires have occurred where PVC decomposition products

appear to have played a significant role. These are fires involving electrical insulation and apparatus, although, in some of these cases, the origin of

the toxic gases is not clearly established. Dyer and Esch [5] describe a fire

"confined to an office copying machine constructed of plastic and Teflon

parts" in which fire fighters sustained respiratory injuries and one fire

fighter died 24 hours later. The "plastic" was not identified and the

involvement of PVC was not demonstrated, although the article was titled,

"Polyvinyl Chloride Toxicity in Fires".

Einhorn and Grunnet [51] described a number of fires in the Salt Lake

City area where PVC was specifically identified by analysis as a major fuel

component. The fires resulted in respiratory and skin injuries to the fire

fighters and other exposed personnel.

Perhaps the prime example of a PVC fire was the New York Telephone

Company fire of 1975 [3]

Fire burned through an eleven story switching

center, fed largely by electrical insulation of wires and cables. A total of

more than 700 fire fighters were involved and many received varying degrees of

respiratory injury. Follow up studies [52] suggest long range health effects

from exposure to PVC smoke. Other more limited studies suggest similar

results [27].

-24 -
7 . CONCLUSIONS

When strongly heated or exposed to a fire environment, PVC-containing

materials decompose at relatively low temperatures to give a nearly quantitative yield of HCZ, in addition to CO and a wide variety of minor organic

products. At higher temperatures, the concentrations of C0£ and its potentiating effect on CO should also be considered when assessing the toxicity of

the combustion products.

HCi appears to be the major toxicant which is responsible for the deaths

that occur following acute inhalation exposures to PVC decomposition products.

HCJZ, is both a sensory irritant and a pulmonary irritant. In the latter role,

it can cause delayed respiratory difficulties, permanent injury, or death. In

one case, however, a laboratory formulation containing the additive zinc

ferrocyanide produced significant quantities of HCN that were probably the

cause of the animal deaths that occurred from 10 min exposures.

PVC decomposition products are usually accompanied in fires by large

amounts of products from other, more combustible, fuels. This, together with

the rapid decay of HC£ concentration presumed to occur in the fire environment, makes it difficult to determine the contribution of PVC to the toxicity

of the atmosphere.

A few cases were noted, principally in fires involving electrical insulation or apparatus, where PVC decomposition products were probably the cause of

the resultant injuries in the fire fighters and other personnel. However,

long term effects on firefighters of chronic exposure to PVC decomposition

products are not well understood and should receive further investigation.

-25-
The toxicity of PVC thermal decomposition products based on LC^q values

falls within the range of values found for many other natural and synthetic

materials. Its relatively low flammability is a positive factor in over-all

fire safety.

8 . ACKNOWLEDGMENTS

The authors wish to thank V. Babrauskas for his contributions to this

manuscript and R. Breese for tabulating some of the data. The authors also

gratefully acknowledge the help of N. Jason, L. Baier, M. Diephaus, A. Durham

and C.S. Bailey who performed the literature search and compiled the

references.

This review was performed under Contract CPSC-IAG-74-25 , Task Order 84-8

from the U.S. Consumer Product Safety Commission, Dr. Rita Orzel, Project

Officer. The opinions expressed herein are those of the authors and not those

of CPSC.

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[4] Bowes, P.C., Smoke and toxicity hazards of plastics in fire. Am. Occup.

Hyg. _1^:143-159 (1974).

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-26-
[6] Dufour, R.E., Survey of Available Information on the Toxicity of the

Combustion and Thermal Decomposition Products of Certain Building

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RC75-T-47, December 1975.

[8] Tewarson, A. and Newman, R.M., The effects of fire exposed electrical

wiring systems on escape potential from buildings. Part 2 - Comparative

fire tests. Factory Mutual Research Corp., Norwood, MA, Tech. Rpt. No.

22491, RC75-T-62, September 1976.

[9] Tewarson, A. and Pion, R.F., The effects of fire exposed electrical

wiring systems on escape potential from buildings. Part 3 - Comparative

laboratory-scale tests, Factory Mutual Research Corp., Norwood, MA,

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[10] Tewarson, A., Fire toxicology - A literature review for polyvinyl

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National Electrical Manufacturers Assoc., Washington, DC, Factory Mutual

Research Corp., Norwood, MA, August 1979.

[11] Barrow, C., Toxicity of plastic combustion products. Toxicological

methodologies to assess the relative hazards of thermal decomposition

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[12] Boettner, E.A. and Ball, G.L., Volatile combustion products of polyvinyl

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[13] Kent, D. and van der Voort, H., PVC - Its characteristics in fire

situations, Carlon Co., Cleveland, OH (1981).

[14] Hinderer, R.K., A comparative review of the combustion toxicity of

polyvinyl chloride, J. of Fire Sciences 2:83-97 (1984).

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^:82-87 (1985-1986).

[16] Dickens, E.D., Jr., A model for the oxygen index of plasticized poly

(vinyl chloride), J. Fire Sciences 123-141 (1984).

[17] Choudhry, G.G. and Hutzinger, 0., Mechanistic aspects of the thermal

formation of halogenated organic compounds including polychlorinated

dibenzo-p-dioxins . Part III: Thermodegradation of organoraetallics and

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[18] Woolley, W., Studies of the dehydrochlorination of PVC in nitrogen and

air. Plastics & Polymers, August 1972, p. 203-208.

-27 -
[19] O’Mara, M.M., High-temperature pyrolysis of poly(vinyl chloride): Gas

chromatographic-mass spectrometric analysis of the pyrolysis products

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[21] Woolley, W., Decomposition products of PVC for studies of fires, British

Polymer Journal ^:186-193 (1971).

[22] Lattimer, R. and Kroenke, W., The formation of volatile pyrolyzates from

poly(vinyl chloride), J. Appl. Sci. 25 : 101-110 (1980).

[23] O'Hara, M., Pyrolysis-gas chromatographic analysis of poly(vinyl

chloride): I. In site adsorption of HCil during pyrolysis and

combustion of PVC, J. Poly. Sci. _9^: 1387-1400 (1971).

[24] Brown, J.E. and Birky, M.M., Phosgene in the thermal decomposition

products of poly( vinyl chloride): Generation, detection and

measurement, J. Anal. Tox. 166-174 (1980).

[25] Stone, J., Hazlett, R., Johnson, J. and Carhart, H., The transport of

hydrogen chloride by soot from burning polyvinyl chloride, J. Fire & Flammability _^:42-51 (1973).

[26] Boudene, C., Jouany, J.M. and Truhaut, R., Protective effect of water

against toxicity of pyrolysis and combustion products of wood and

poly(vinyl chloride), J. Macromol. Sci. Chem. A1 1 ; 1529-1545 (1977).

[27] Tashkin, D.P., Genovesi, M.G., Chopra, S., Coulson, A. and Simmons, M.

Respiratory status of Los Angeles firemen. Chest 7 1 :445-449 (1977).

[28] 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

(U.S.) Nat. Bur. Stand. (1982).

[29] Alarie, Y., Toxicological evaluations of airborne chemical irritants and

allergens using respiratory reflex reactions. In: Inhalation

Toxicology and Technology, Ed. by B.K.J. Leong, Ann Arbor Science

Publishers, Ann Arbor, MI, pp. 207-232 (1981).

[30] Anderson, R.C. and Alarie, Y., Acute lethal effects of polyvinyl

chloride thermal decomposition products in normal and cannulated mice.

Abstracts of 19th Annual Meeting of Society of Toxicology, Washington,

DC, p. A3 (1980).

[31] Kaplan, H.L., Grand, A.F., Rogers, W.R., Walter, G.S. and

Hartzell, G.E., A research study of the assessment of escape impairment

by irritant combustion gases in postcrash aircraft fires. Final Report,

Grant No. DTFA03-81-0065 , Southwest Research Institute, San Antonio

(1984).

-28-
[ 32 ] Barrow, M.S., Alarie, Y. and Stock, M.F., Sensory irritation and

incapacitation evoked by thermal decomposition products of polymers and

comparisons with known sensory irritants, Arch. Environ. Health 33 ; 79-88

(1978).

[33] Wong, K.L., Stock, M.F., and Alarie, Y.C., Evaluation of the pulmonary

toxicity of plasticized polyvinyl chloride thermal decomposition

products in guinea pigs by repeated CO

2 challenges. Tox. & Appl. Pharm.

20:236-248 (1983).

[34] Cornish, H.H. and Abar, A.L., Toxicity of pyrolysis products of vinyl

plastics. Arch. Environ. Health 22.: 15-21 (1969).

[35] Cornish, H., Toxicity of thermal degradation products of plastics.

In: Symposium on Products of Combustion of (Plastic) Building

Materials, Armstrong Cork Co., Lancaster, PA, March 1973, p. 30-33.

[36] Hofmann, H. Th. and Oettel, H., Comparative toxicity of thermal

decomposition products. Modern Plastics 46 ; 94-100 (1969).

[37] Hofmann, H. Th. and Sand, H., Further investigations into the relative

toxicity of decomposition products given off from smoldering plastics,

JFF/Comb. Tox. J^:250-258 (1974).

[38] Kishitanl, K., Study on Injurious properties of combustion products of

building materials in initial stage of fire, J. of the Faculty of

Engineering, University of Tokyo (B) 31 : 1-35 (1979).

[39] Kishltani, K. and Nakamura, K., Toxicitles of combustion products,

JFF/Combustion Toxicology 2*10^”123 (1974).

[40] Kishitani, K. and Yusa, S., Study on evaluation of relative toxlclties

of combustion products of various materials, J. of the Faculty of

Engineering, The University of Tokyo, 35:1-17 (1979).

[41] Hilado, C.J. and Crane, C.R., Comparison of results with the USF/NASA

and FAA/CAMI toxicity screening test methods, J. Comb. Tox. ^: 56-60

(1977).

[42] Alarie, Y. and Anderson, R.C., Toxicologic classification of thermal

decomposition products of synthetic and natural polymers, Toxicol. Appl.

Pharmacol. 57 : 181-188 (1981).

[43] Anderson, R.C., Croce, P.A., and Sakura, J .D . , Study to assess the

feasibility of incorporating combustion toxicity requirements into

building material and furnishing codes of New York state. Final report

to the Dept, of State, Office of Fire Prevention and Control, Albany,

NY, A.D. Little, Inc., Reference #88712, May 1983.

[44] Herpol, C., Comparative study of the toxicity of combustion products

from flame retardant and untreated materials. Fire & Matls. 193-201

(1983).

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[45] Higgins, E.A., Fiorca, V., Thomas, A.A. and Davis, H.V., Acute toxicity

of brief exposures to HF, HCJl, NO

2 and HCN with and without CO, Fire

Technology ^;120-130 (1972).

[46] Darmer, K.I., Kinkead, E.R. and DiPasquale, L.C., Acute toxicity in rats

and mice exposed to hydrogen chloride gas and aerosols, Amer. Ind. Hyg.

Assoc. J. 35 :623 (1974).

[47] Carroll, W.F., Thermal decomposition of polyvinyl chloride in large

apparatus: kinetics of generation and decay of hydrogen chloride.

Proceedings of First International Symposium on Fire Safety Science,

National Bureau of Standards, Gaithersburg, MD, Oct. 7-11, 1985.

[48] Stark, G.W.V., Evans, W. and Field, P., Toxic gases from rigid poly

(vinyl chloride) in fires. Fire Research Note 752, Fire Research

Station, Borehamwood, Herts, England (1969).

[49] Packham, S.C. and Crawford, M.B., An evaluation of smoke toxicity and

toxic hazard of electrical nonmetallic tubing combustion products, J.

Fire Sci. _2:37-59 (1984).

[50] Lowry, W.T., Juarez, L., Petty, C.S. and Roberts, B., Studies of toxic

gas production during actual structural fires in the Dallas area,

J. Forensic Sci. 30:59-72 (1985).

[51] Einhorn, I.N. and Grunnet, M.L., The physiological and toxicological

aspects of degradation products produced during the combustion of

polyvinyl chloride polymers. Flammability Research Center, University of

Utah, Salt Lake City, UT, Grants No. 5-9006, 7-9005, and R-6002, 1980,

Sect. 3, p. 1-47.

[52] Wallace, D., Nelson, N. and Gates, T., Polyvinyl chloride wire

insulation decomposition. II. Consideration of long term health

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[54] Burleigh-Flayer , H., Wong, K.L., and Alarie, Y., Evaluation of the

pulmonary effects of HCil using CO

2 challenges in guinea pigs. Fund. & Appl. Tox. 2=978-985 (1985).

-30 -
Table 1 . Compounds Identified in Pyrolysis and Therraooxidation Products

of Poly(Vinyl Chloride) and Some Vinyl Copolymers [20]

Compound Pyrolysis Thermooxidation

Carbon dioxide

Chloromethane

Cyclopentane

Cyclopentadiene

Cyclohexadiene

Benzene

Toluene

Dioxane

Xylene

Styrene

Methyl styrene

Indene

Naphthalene

Butadiene

Vinyl chloride

Acetaldehyde

Methylcyclopentene

Chlorobenzene

Divinylbenzene

Cyclopentene

Trichloroethylene

Chloroethane

Chloropropene

Propanal

Methyl ethyl cyclopentane

++

+

+

+

+

+

+

+++

Trimethyl cyclopentane

Methyl cyclohexene

Methyl indane

Cyclohexene

Trimethylbenzene

Dichloroethylene

Acrylonitrile

Hydrogen cyanide

Acetonitrile

+

++

++

+ +

+

+

+

Dichlorobutadiene

Dichloropentene

Trichloropropane

Dichlorobenzene

Trichlorobenzene

++

++

+

++

-31 -
Table 1. (continued)

Compound

p-Chlorobenzonltrile

Dichlorobenzonitrile

Dichloropropene

Methylmethacrylate

Trimethylpentene

Dichlorobutylene

Dichloropentadiene

Dichlorocyclopentene

Benz aldehyde

Trichlorobutylene

Chloropyridlne

n-Propylbenzene

Chlorobenzonltrile

Dichlorotoluene

p-Dichlorobenzonitrile

Methylnaphthalene

Chloronaphthalene

Tertiary butyl methyl phenol

Chlorostyrene

Diphenyl

Tetradecylene

Pentadecylene

Dichloroethyl benzene

Diphenylethane

Di-tert-butyl methyl phenol

Pyrolysis Thermooxidation

+

+

— +

+ +

— +

+

+

— +

— +

+

+

+

— +

+

+

+

+

+

— +

+

+

++

+

Hexadecylene

Diphenylbutylene - Hydrogen chloride ++

++++

++: main components

+: other products present in amounts less than 2% of total products

not detected

-32 -
Table 2. Toxicity Measurements of Various PVC Materials and

PVC-Containing Products [34]

Sample Description

Max CO

(ppm)

Average

COHb^

(%)

LC5o^

(mg/il)

A homopolymer > 3000 72 3.1

B homopolymer > 3000 69 3.3’

C homo polymer > 3000 51 5.1

E electrical wire insulation 2000 20 >10.3 and

G wire insulation 800 - > 15.3

D vinyl chloride: vinyl

acetate - 85:15

8000 36 > 5.1

F floor tile > 3000 - > 15.3

^Blood taken from dead animals.

^Rats were exposed for 115-140 minutes, under ramped heating conditions.

Lethalities include a 24 hr post-exposure period.

-33 -
Table 3. Dependence of PVC Smoldering Toxicity on Temperature of Decomposition in the

DIN Toxicity Test Method [36,37]

Air Dilution^

( i/hr )

Effective

Specimen

Charge

(mg/i)

Temperature

(°C)

COHb

(%) # Deaths/# Animals Tested

100^ 50 200 < 15 0/12

300 25 10/12

400 45 11/12

500 70 12/12

600 76 12/12

400^^ 20 300 < 10 2/12

400 < 10 4/12

500 25 3/12

600 40 8/12

900^ 10 300 < 10 0/12

400 < 10 0/12

500 16 0/12

ra

600 26 0/12

^ In all cases, 100 £./hr of air passed through the furnace containing 5 g

samples

^ An additional 100 il/hr of air was added prior to animal exposures resulting

in 50 mg/£ specimen charges.

^ Specimen charge reduced to 20 mg/H by an additional 400 il/hr of air.

^ Specimen charge reduced to 10 mg/il by an additional 900 il/hr of air.

-34 -
Table 4. Toxicity of PVC Decomposition Products in

the Presence and Absence of Water [26]

LC^q (mg/Jl)^ HCJi (ppm)

Temperature

(°C) Mode w/water w/o water w/water w/o water

400 NF 166 33 0 10,000^

850 F 145 25 0 7,500<=

^Rabbits were exposed for 30 minutes and observed for 4 hours post-exposure.

NF: non-flaming

F: flaming

air flow rate: 120 il/hr

^At 33.3 mg/loading.

*^At 25.0 mg/

loading.

-35 -
Table 5. Toxicity of Some PVC Materials [43]

Material

Test

Procedure

LC5 Q Values

Animal Combustion 30 Min + 14 days

Species Mode ( rng/g, )

Vinyl wall NBS Rats NF 51 .0 covering NBS Rats F 39.3

Pittsburgh Mice M 14.0

Conduit NBS Rats NF 37.0

NBS Rats F 29.5

Pittsburgh Mice M 9.8

C-PVC Pipe NBS Rats NF 9.1

NBS

^ Rats F 16.0

Pittsburgh Mice M 4.7

Vinyl- Pittsburgh Mice M 16.5

coated wire

NF: Non-flaming.

F: Flaming.

M: Mixed includes both non-flaming and flaming.

*: Reported values converted to mg/ £. as follows:

LL^q Value (g)

600 i (Volume of dilution air) * = rag/

- 36 -
Table 6. Comparison of the Toxicities of a Fire

Retarded and Non-Fire Retarded PVC

Floor Covering and Wall Covering [44]

Fire Temp

#Dead/ COHb^ Mean CO

Material Retardant (°C) Mode ^Tested (%) (ppm)

Floor covering 500 NF 0/6 54 2190

600 F 16/25 57 4000

700 F 14/18 77 3460

500 NF 18/18 76 6420

600 NF,F ^ 4/27 77 1990

700 F 16/18 74 3180

Wall covering - 500 NF 5/6 78 3140

600 F

^ 17/18 78 6880

700 F 0/6 32 1520

500 NF , 15/17 84 3850

600 F

^ 14/17 71 4670

700 F 1/6 65 680

^ COHb is the mean value of the dead animals unless there were no deaths, in

which case, it is the mean of the live animals.

^ Contains phosphate plasticizers and antimony trioxide.

^ Contains phosphate and chlorine-containing plasticizers and antimony trioxide.

Short bursts of flames.

-37 -
co

<u -

Cd

(U

<4-1 C

(U 00 o

1“’^ o 1 ^s t<u o

W) o “ >,

•H ^ 4J

j_iF—j b

CO

PQ

0) rH

Xi

ca H > ^

(U o a

S-i « • T3C '> CO

4-1 CO+1c

CO0) s

CJ

t-H 0)

CO CO d ••

4-1

C

CJ -H c s

rH l-( cO (U s ^

•H e C 3 < Zc - ° c CO 4J ^ lU CO ^ H uSO

hOC

•HT3

03O

-J

CO

CO

03 s m

CNJ CO

o^m

-nT

+1

ONmo

fo

m loi o cn o o

-It

O <0 CM

•• •• •• •• •• • Cs| *——

-H CM vO t" 00 -—( Csl rn <? Lpi o o(Tv

CTv O

(T1

m o o o o o -H m -T cn <f o

CM cn

O CM -T vO ^ c^ <r <f -T <r

CM (TO -T lO vO ovO

v£>

<uCOco

o.

CO

(U

0)oc

CO T3

•Ho>

COco

•H

x;0)M

0)t T3C

(U -C

>>

T5

<U

Uioo

COa

<0

CJc I 00

c^I
Table 8. Comparative Toxicities of Various Materials

Using the NBS Test Method [28]

LCso^ LC5o^

(mg/Z) (mg/Jl)

Material Flaming Non-Flaming

ABS^ 19 31

Douglas Fir^ 40 23

Douglas Fir^ 41 20

Flexible Polyurethane Foam^*'^ > 40 27

Modacrylic^ 4.4 5.3

Polyphenylsulf one^ 20 9.5

Polystyrene^ •39 > 40

Poly tetraf luoroethylene^

PVC°

0.045 0.045

17 20

PVC plus zinc f errocyanlde^ 15 11

Red Oak^ 57 30

Rigid Polyurethane Foam^ 13 > 40

Wool^ 28 25

^30 minute exposures plus a 14-day post-exposure observation period

^In large cup furnace (1000 ml)

*^In small cup furnace (300 ml)

-39-
Table

9.

NBS

10

Minute

Test

For

Rapidly

Acting

Toxicants

[28] s3 ^ S 2 S

•H o a « 2 CU

to ' 2S3e

•HX

CO 2

CO

<U Q3

CDO

(U 2 2o

CO • CO 3 2 e <aX

(UI u

COoa 33OU322 ^S U 3 o H ^32O23u32

VsO o CO LO NO

oo

m ON ON 2 O fO

OO

vO

'0" Oo

ON

(N

m

CM

ao

CN

CN

Oo oo oo oCM

v£) vO

v3 CO

NO om NO oo oo oo oo oo oo2 Om

NO2 O

<r2 2U3

NJ1 CJ>2

CO>N32

»>i O223>33m2o233X3u332eo2 32 2 2 3 3 X 3 O >N a O X O 3 l-i in m 3

CVJ

X 3

nO

m 2 3e 3 2 3 3 2 3 N • X 2 2 2 2 3 2 X s O • 2 U bO S > 3 O 2 2 a a 3 1 • 3 2 bO 2 2 C O 1 '—

3 B 3

bO 2 CtJ

O

a rH 2 N1 o 1 1 CJ m CJ 1 > > 2 2 3 2 o

•<r
Table 10. Toxicological Results From HCil Exposures

With and Without CO [45]

Exposure

Animal Time (min)

LC5 Q (ppm)

HCil HCJl + CO

Rat 5 41000 (34800-48300)* 39000 (35100-43400)

Mouse 5 13700 (10300-18300) 10700 (6900-16400)

*95% confidence limits

-41 -
Table 11. Toxicological Results from HCil Exposures

With and Without a Water Mist [46]

LC3 Q (ppm)

Animal

Exposure

Time (min) Dry Vapor Moist Aerosol

Rat 5 41000 (34800-48300)* 31000 (26800-35800)

30 4700 (4100-5400) 5700 (4900-6600)

Mouse 5 13700 (10300-18300) 11200 (10000-12500)

30 2600 (2300-3100) 2100 (1800-2600)

*95% confidence limits

-42-
Table

12. A

comparison

of

HCL

gas

toxicity

and

PVC

toxicity

VI

0)oc vO oo 00

mm cn <m cn oo

<0u

<0

(4-i (0 oi

<r CN CM •4* -d0) o S o o u O lO O. o o 3 X o o- v£>

D.I hJ

W CM a

4.1 1—

a.

O COa iJ o O o o O o o o o o O o

td V.I o O o o o o o o o o o o O <u 0) O » CO o 00 lT) o crc <r • M3 cri ON M3 c X 4-) *n M3 00 m o CM M3 m m M3 o u 4-) CO CJ f-H CM I—

r-H

u

X £

(U T3 1 b Ci4 Cl4 • s s s Os z z z z

<u

l-l t 3 0)

w

4J CO S >d* 'd' 'd' -d"

CO

O -r^ cO 1^ rH 1 1 o a -u X

Oh

X .—

0>

o>3 ^ CO (1) O S fi o o o o o o o o o o

CL *H H-l c*3 cn

m cn cn CO cn CO CO CO

X 4J s W W

00 00 C C

H-lL4 i-4 03

<B (U Li > > O o 3 o o

1—

X CO r—t <u r-t 03 <u

H-l

U CL 1-^ CL 4J

Li > cd •r4 CO r^ cO

(B 01 CL, 3 L> CL 01 4J CL

O

4J CO H-i CO

O

CO 00

X I-^ 3 CL3 00 r4 3 O

XX > X > (—

r-4 bO

C (3 Cl, c c Oh o O , o •r^ o 1 c X oO > U a X > u CJ >

r~i

CO <u a 01 •u 3 c CO O

•<

X 1

43 -

Flaming Nonflaming

Mixed

flaming

and

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

UcS. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

NBSIR-85/3286

2. Performing Organ. Report No. 3. Publication Date May 1986

4. TITLE AND SUBTITLE

TOXICITY OF THE PYROLYSIS AND COMBUSTION PRODUCTS

OF POLY (VINYL CHLORIDES): A LITERATURE ASSESSMENT

5. AUTHOR(S)

Clayton Huggett and Barbara C. Levin

6. PERFORMING ORGANIZATION (If joint or other than NBS, see instructions) 7. Contract/Grant No. CPSC-IAG-74-25

NATIONAL BUREAU OF STANDARDS

U.S. 0B>ARTMB4T OF COMMKCE 8. Type of Report & Period Covered

GAITHERSBURG, MD 20899

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

Constomer Product Safety Commission

Bethesda, MD 20207

10.

SUPPLEMENTARY NOTES

I I 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 surve^mention it here) Poly(vxnyl chlorides) (PVC) constitute a major class of synthetic plastics. Many

surveys of the voluminous literature have been performed. This report reviews the

literature published in English from 1969 through 1984 and endeavors to be more

interpretive than comprehensive. PVC compounds, in general, are among the more fire

resistant common organic polymers, natural or synthetic. The major products of

thermal decomposition include hydrogen chloride, benzene and unsaturated hydrocarbons

In the presence of oxygen, carbon monoxide, carbon dioxide and water are included

among the common combustion products . The main toxic products from PVC fires are hydrogen chloride (a sensory and pulmonary irritant) and carbon monoxide (an

asphyxiant). The LC^g values calculated for a series of natural and synthetic

materials thermally decomposed according to the NBS toxicity test method ranged from

0.045 to 57 mg/i in the flaming mode and from 0.045 to > 40 mg/i in the non- flaming

mode. The LC^g results for a PVC resin decomposed under the same conditions were 17

mg/i in the flaming mode and 20 mg/i in the non- flaming mode. These results indicate

that PVC decomposition products are not extremely toxic when compared to those from

other common building materials. When the combustion toxicity (based on their HCi

content) of PVC materials is compared to pure HCi experiments, it appears that much of

the post-exposure toxicity can be explained by the HCi that is generated.

12. KEY WORDS (S/x to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

Carbon monoxide, combustion products, hydrochloric acid, large scale fire tests,

pol3Tvinyl chloride, pyrolysis products, small scale fire tests, toxicity.

13. AVAILABILITY

Uni imited

I I For Official Distribution. Do Not Release to NTIS

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

20402.

Order From National Technical Information Service (NTIS), Springfield. VA 22161

14. NO. OF

PRINTED PAGES

48

15. Price

$9.95

USCOMM-OC SS-6006