Document EXqOL2M8a75d6VYmywLx8eQN

IMPLICATIONS OF SPECIES DIFFERENCES IN ASSESSING THE TOXICITY OF PVC COMBUSTION PRODUCTS AND ______IRRITANTS SUCH AS HC1 TO HUMANS___________ Presented at Interwire Conference in Atlanta, Georgia, November, 1989 BY: ROBERT K. HINDERER, PH.D. THE VINYL INSTITUTE DATE: JULY 1989 Correspondence Address: THE BFGOODRICH COMPANY 3925 EMBASSY PARKWAY AKRON, OHIO 44313 BFG51083 I c; Toxicity of the Pyrolysis and Combustion Products of Poly (Vinyl Chlorides): A Literature Assessment Clayton Hugged and Barbara C. Levin* I S Department of Commerce. NnUonal Bureau of Standards. National Engineering Laboratory. Center for Fire Research. Gaithersburg. MD 20899, USA ` Poly{vinyl chlorides) (PVC) constitute a major class of synthetic plastics. Many surveys of the voluminous literature hav v been performed. This report reviews the literature published in English from (969 through 198-4 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^t values calculated for a series of natural and synthetic materials thermally decomposed according to (he NUS toxicity test method ranged from 0.045 to 57 mg I"1 in the flaming mode and from 0.045 to > 40 mg I" ` in (he non-flaming mode.'The LCS0 results for a PVC1 resin decomposed under the same conditions were 17 mg l1 in the flaming mode and 20 mgl * 1 in the non-flaming mode. These results indicate that PVC decomposition products are not extremely loxic when compared with those from other common building materials. When the combustion toxicity (based on their HCI content) of PVC materials is compared w ith pure HCI experiments, it appears that much of the post-exposure toxicity can be explained by the HCI (hut is generated. Keywords: carbon monoxide, combustion products, hydrochloric acid, large-scale fire tests, polyvinyl chloride, p\ rolysis products, small-scale fire tests, toxicity. NTROD LOTION 1VI>! 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 19X4.' More than half of this amount, which correspond?, to an average of about 301b per person, is u-wd in building products, including pipe and fittings, flooring, siding, and a wide variety of other construction products.: Much of this goes into residential construc tion. Other major uses include^ packaging, electrical insulation lor wire and cable, interior furnishings and a hot 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 tires, injuries to firemen and buildingoccupants have been attributed to its thermal decomposition or combustion products.1 ' This, together with PVC's wide distribution, has led to numerous studies of the nature of (he 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 reviews was performed at the Underwriter's Laboratories in 1963.*' An extensive survey was made by Tewurson at Factory Mutual in 1 y75 6. in which he cited 262 references.7 9 In a supple ment prepared in 1979. he cites an additional 56 refetcnees."' The literature has increased in volume at an accelerated pace since that time. Barrow, in his PhD 'Author io whom jll correspondence should he addressed. thesis, provides an excellent review of the toxicity of the thermal decomposition products of PVC. with emphasis on experimental methods and physiological effects.n Boettner and Ball reviewed work on the composition of the volatile combustion products of PVC in 1981/2 Kent and van der Voort described the behavior of PVC in fires in 1981.13 Recently. Hinderer has reviewed the combus tion product toxicity of PVC.1* Despite this volume of publications, it is difficult to obtain a clear picture of the role of PVC in fire?. Reported data are difficult to compare and sometimes contradic tory. A number of reasons may be cited for this difficulty: (!) Pure PVC homopolymer (PVC resin) is almost never encountered outside the research laBoratory. Most useful products arc made from compositions com pounded with a variety of additives designed to improve their properties. These additives include polymerization catalysts, plasticizers, lubricants, heal 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 PVCs to 100 phr in very flexible PVCs. 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. (2) Methods of thermal decomposition or combustion of the samples vary widely from one study to another, particularly with respect to the thermal and atmosph- BFG51084 Rin-iii J January (<J87 rcor. o Jtt-. sk|K&!B5 T(nm NBSIft 85-3286 TOXICITY OF THE PYROLYSIS AND COMBUSTION PRODUCTS OF POLY(VlNYL CHLORIDES): A LITERATURE ASSESSMENT Clayton Huggett Barbara C. Levin U.S. DEPARTMENT OF COMMERCE Natfohaf 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. Dk+ctor BFG51085 to