Document MJ3aNDpwVz9MM6w6bn8JgXYb9

Acute Inhalation Toxicity of Vinyl Chloride to Laboratory Animals E. MASTROIVIATTEO, M.D., A. M. FISHER, Ph.D., H. CHRISTIE, B.Sc., and H. DANZIGER, M.D. Diinsion of Industrial Hygiene, Ontario Department of Health, Toronto, Ontario; Department of Physiological Hygiene, School of Hygiene, University of Toronto, Toronto, Ontario; and Welland County General Hospital, Welland, Ontario Introduction scribed as very slight. 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This latter case was reported by Harris.' exposed to a concentratiou of about IS per cent Such hums may occur with other highly volatile in air. Recovery was very rapid with no apparent materials when sprayed onto the hands as a liquid untoward effect even after prolonged anesthesia. under pressure. Lehmann and Flurv1 noted that vinyl chloride Filatova and Gronsbcrg" in 1957 reported on was highly nan-otic but had a wide margin be hygienic conditions in a polyvinyl preceding tween its narcotic and lethal concentrations. Its plant In the U.S.S.R. The plant was engaged in local irritating effect and its toxicity were de- the |>olyincrization of vinyl chloride by means of 394 R&S 136091 i | 1 j j J | 1 JI j ; ; Industrial Hygiene Journal 39o R&S 136092 a catalyst. Air sampling was done and the con centration of vinyl chloride w;is found to vary from about 20 ppm to about 315 ppm. (U.S.S.R. Threshold Limit Value: 1 mg/liter or about 400 ppm). A spastic type blood vessel disorder was described in workers from this plant. Because of the recent fatalities mentioned above it was decided to undertake acute initia tion studies in laboratory animals with commer cially available vinyl chloride. This was done both for comparison with earlier work and to provide information on the acute response and pathologi cal changes in more than one species of laboratory animal. Experimental Materials and Procedures 7inyi Chloride: The vinyl chloride was supplied in a metal cylinder under pressure. A commercial grade with the following specifications was used: Specific fnrrity At 20*C Water content Boiling range *C Hydrogea chloride content Aostytena Acetaldehyde Iron Purity (per cent) Impurities (per cent) 0.W3H5.9&3 None -II to -9J None 10 ppm rnerimnm 20 ppm maximum Essentially iron free 90JS mtiimum Pure vinyl chloride is a colorless eas at room temperature; its boiling point is -- l3.9aC. It has a sweetish odor. Its flash point is given at --7SC and its explosive limits in air from 4 to 22 per cent. It has the molecular formula CH*:CHC1. Animals: Mice, rats and guinea pigs were used in the study. Test and control animals were taken from the same laboratory stock. All were fed a standard commercial diet and housed in the same way. Ml were of the same stage of development. Equipment: The inhalation chamber capacity was 56.6 liters. It was equipped with a viewing window and an inlet tube. Vinyl chloride was re leased in gaseous form through an adjustable valve on the top of the containing cylinder, then through connecting rubber tubing uud a recali brated Fisher flow-meter. Fresh air was pumped by motor at an adjustable controlled rate through a meter. The streams of air aud vinyl chloride were combined at appropriate rates of flow by a glass Y-tubc leading through further rubber tub ing to the animal chamber inlet, to deliver a continuing stream in the desired proportions. Calculations and adjustments were made to pro duce the following flow concentrations of vinyl chloride in air for delivery: 10, 20, 30 and 40 per cent. All concentrations arc expressed in this re port as per cent by volume in air. No determina tions of vinyl chloride concentrations were done in the test chamber during the experiments. Experimental Procedures: Different groups of five mice, five rats and five guinea pig3 were placed in the chamber and exposed for thirty minutes to concentrations of 10, 20 and 30 per cent vinyl chloride in air. Similar groups of con trol animals were maintained but not exposed to vinyl chloride. At the end of thirty minutes ex posure the test animals were immediately re moved to fresh air. An additional group of five guinea pigs was exposed to a concentration of 40 per cent vinyl chloride in air. In all 65 experimen tal animals wore involved. Observations were re corded on the animals during and after exposure. The animals which died either during the ex posure or after a delay period were autopsied soon after death. Two weeks after the exposure sur viving test animals and controls were sacrificed by a blow to the head with the exception of four control rats which were killed by exsanguination. All animals were examined for gross pathologi cal changes. Tissues were removed from all ani mals for microscopic examination. The lungs, liver, kidney and heart were removed in all cases. The brain, adrenal, spleen, trachea, lymph nodes, and the eye were removed from represen tative animals in each group for study. The tissues were preserved in formalin aud sections made for staining with hematoxylin-eosin. Special stains were made where indicated. Observations Control Animals: N'o symptoms were exhibited by the 15 control animals and no deaths occurred. Ten Per Cent Vinyl Chloride: The response of animals exposed to this concentration is recorded below in summary form: Exposure Time (minutes) 30 Response Slight irritation in mice and rut*. Xncroed motor activity Ant in mice, then rst* sod cuinea piffS. Iocre*4d motor activity in all spade*; twitching ot extremities ia mice. Pronounced tremor, unsteady gait nd muscular incoordination in all species. Mice and rata In side position*, muscular incoordination, tremors and twitching of extremities in cuinea pi^s. Nice aad rats unconscious, guinea pica very unsteady but still itacdini- Mtoc and rata in deep narcoois; ruioea pica In side position with tremors--one unconsdoua. Exposure was stopped and the animals removed to fresh air. All recovered within five minutes. Tictntij Per Cent Vinyl Chloride: The response I 396 October, 1960 of animals exposed to this concentration is re- Table I corded below in summary form: Number of Deaths in Different Groups of Five Exposure Time (minutes) RfSpOOM Mice, Ruts and Guinea Pigs Exposed for Thirty Minutes to Varying Concent rations of Vinyl 1 Immediate tmtmtioa \tx mice and rati. 3 Muscular incoordination in mica mnd Chloride in Air i rats. Mioe mad rats on their sides with marked Vinyl chloride concentration Laboratory animal fretnorm mad twitching of the extremi* (per cent hf Tots! tie*; unsteadiness mad muscular inco volume in nr) Mice Rats Guinea pigs ordination in guinea pica. 10 Mice mnd rmtm unconscious with rapid 10 0/3 0/3 C/3 0/13 irregular breathing; guinea pigs ua* 20 1/3 0/3 0/3 1/13 eoomdoum but showing tnmrked twitch- 30 3/3 3/3 1/3- U/1S ing. 40 -- 2/3* 2/3 13 Ail moimrnim in deep narcosis; respirations irregular mad rapid. Tout 9/13 3/13 3/20 M/30 30 Deep nmreoeim; breathing eta* mnd ihal low. * A delayed death occurred within24 hours following exposure. 33 Bremthing erased in one mouse; frothing it mouth mad nostrils in mice mad rati. 30 AU animals tn deep narcosis. Forty Per Cent Vinyl Chloride: Only five guinea Exposure was stopped and the animals removed to fresh air. Mice and rats recovered faster than the guinea pigs and appeared normal within five minutes except for one mouse which was dead. The guinea pigs continued to show muscular in coordination, unsteadiness on their feet until 20 minutes after removal from exposure. Thirty Per Cent Vinyl CWoride: The response of animals exposed to this concentration is recorded below in summary form: pigs were exposed to this concentration. Signs of irritation were immediately apparent. Muscular incoordination appeared within seconds. After five minutes all the guinea pigs were unconscious with slow shallow breathing. At the end of the exposure period one guinea pig was dead and the remaining four were in deep narcosis. These sur vivors took 30 minutes to return to their normal appearance and activity, but one died within the following 24 hours. The number of deaths occurring in different E{jlc"aTMinu'eiori)u," 1 RpTM* Hioa *bowd imt&Uoa immediately tad tbe rate showed irritation quickly thereafter, HuaeuUr incoordination in mice and fata. groups of five laboratory animals exposed for thirty, minutes to varying concentrations of vinyl chloride in air is shown in Table 1. Pathological findings 2 MiOft and rata in aide position with marked tremors and twitching of the Gross pathological and histological studies were extremities; muscular ineoordjnatioQ carried out. The findings are summarized below. in guinea pigs with developing pmfmly* sis of the extremities. All animals unconscious; rapid irregular respirations in mica and rate with Control Animals: These animals showed no gross or microscopic evidence of damage. Ten Per Cent Vinyl Chloride: All test animals frothing about noae and mouth; survived this exposure. They were sacrificed two twitching of extremities still occurred weeks later. On gross examination there was evi 10 occasionally in guinea pigs. Respirations *topi>ed in mice; breathing dence in mice of slight hyperemia of the lungs. alow and shallow in nita; guinea pics Tliis was less marked in rats. Guinea pigs showed still exhibited occasional twitching no difference from control animals. On histologic movements Of the extremities. Breathing stopped in rats; respirations slow and shallow in guinea pizs; twitching of extremities still protect in guinea pics. examination the mice showed very slight engorge ment of the pulmonary vessels. One mouse showed degenerative changes in the tubular epi thelium of the kidney with hydropic swelling- 30 Mice and rats still; guinea pigs in deep The rats showed slight congestion of the capillar narcosis with slow shallow breathing ies in the lung. Lungs in the guinea pig were also Exposure was stopped and the animals removed slightly more hyperemic than those of the control to fresh :iir. The mice and ruts were dcud. The animals. guineu pigs took 25 minutes to return to their Ttrenly Per Cent Vinyl Chloride: One moure normal appearance and activity. One guinea pig died as a result of 30 minutes cxjxjsure to this from this group died within 24 hours following concentration. I'ulmnnnry congestion was evident exposure. on gross examination. Microscopically, there was t l II I R&S 136093 j Industrial Hygiene Journal 397 engorgement of the blood vessels in the lung with patchy arcus of atelectasis and minimal edema. The kidneys showed minimal degenerative changes in the epithelium of the convoluted, tu bules. The test animals surviving this exposure were sacrificed in two weeks. On gross examination, congestion of the lungs was present in all species, but it was more marked in the mice and rats than in the guinea pigs. Histologically, there was evi dence of pulmonary congestion In exposed ani mals. Some fatty infiltration was present in the liver of one rat. All other tissues studied appeared normal. Thirty Per Cent Vinyl Chloride: Gross examina tion of the animals wliich died as a result of this exposure revealed congestion of the lungs with hemorrhagic areas. The mice and rats in addition showed congestion of the liver and kidney. The one guinea pig death was delayed. In this animal there was marked congestion of the lungs with hemorrhages and the liver was distended and very friable. The microscopic changes in the animals which died included marked engorgement of the pulmonary blood vessels with edema and hemor rhages in the lungs. The trachea of one rut showed superficial desquamation of the epithelium.. Con gestion was also evident in the Uver and kidney of the mice and rats. The liver of the guinea pig which had the delayed death showed severe fatty degeneration of the liver confirmed with frozen sections stained with Sudan III. The four surviving guinea pigs were sacrificed two weeks later. Marked pulmonary congestion was present with hemorrhagic areas and edema. In one case there was evidence of secondary bac terial infiltration. The liver in these guinea pigs gave the appearance of fatty infiltration but no fat was demonstrated on frozen section. Forty Per Cent Vinyl Chloride: One of five guinea pigs exposed to this concentration died during the exposure and another died within 24 hours. The two which died showed marked con gestion of the lungs with hemorrhages on gross examination. This was also evident on micro scopic examination. The liver of one of these gave the appearance of fatty infiltration, but no fat could be demonstrated on frozen section. The three surviving guinea pigs were sacrificed two weeks later. Marked congestion of the lungs with hemorrluigc was evident on both the gross and microscopic examination. In one guinea pig, the tracheal epithelium was completely absent. Pathological studies which were made of the brain, heart, splivti. adrenals, lymph nodes and the eyes showed no difference Ix-tween controls and animals dying as a result of exposure or l>etween controls and the surviving animals sacri ficed two weeks after exposure. There was a tendency for the blood to remain unclotted in the animals dying during exposure. This feature was noted in the two human fatalities mentioned ear lier but it is not a-specific characteristic of vinyl chloride. Discussion The response of guinea pigs to inhalation of vinyl chloride was similar to that reported by Patty, Yant and Waite. The guinea pigs in our study, however, tolerated a greater exposure dur ing the experimental period than either the mice or rats. The results in mice agreed closely with those reported by Peoples and Leake. Rats were similar to mice in their response. The pathological changes in animals which died as a result of exposure were mainly those of vascular engorgement of the lungs with hemor rhages and edema. The severity of these changes varied with the severity of exposure. In the higher concentrations, pulmonary change was marked with severe damage to the tracheal epithelium. Congestion of the liver and kidneys also occurred in test animals. These changes are similar to those reported by Patty and associates. Evidence of pulmonary congestion was still present in surviving animals sacrificed two weeks after exposure. Patty and associates reported that such changes had disappeared in about eight days. Degenerative changes in the tubular epithelium of the kidney were noted in one mouse d.ving as a result of exposure and in one mouse sacrificed two weeks after being exposed. Such changes, however, were minimal and not shown by other animals in the group. One of the guinea pigs with delayed death fol lowing exposure showed severe fatty infiltration of the liver. Changes suggestive of fatty infiltra tion were observed in other exposed animals but not confirmed by frozen sections stained with Sudan III. Summary Separate groups of laboratory animals com prising five mice, five rats and five guinea pigs were exposed in an inhalation chamber to concen trations of 10, 20 and 30 per cent vinyl chloride in air for 30 minutes. An additional five guinea pigs were exposed to a 40 per cent concentration for a similar period of time. The response by each of the three species to these concentrations is noted. Inhalation of these relatively high concentra tions produced narcosis and death. Mice were the most susceptible with guinea pigs considerably mure resistant. Rats were similar to mice in their f 338 October, 1360 response. Exposure to ten per cent vinyl chloride in air produced deep narcosis in mice and rats but no deaths: 30 per cent concentrations killed mice and rats. Exposure of guinea pigs to 20 per cent produced deep narcosis; but three of five guinea pigs survived exposure to 40 per cent con centration. Animals dying as a result of exposure were autopsied shortly after death. Survivors and con trol animals were sacrificed two weeks later. Gross pathological and microscopic studies were done and these findings are described. The principal pathological changes in animals dying from exposure were congestion of the lungs with pulmonary edema and hemorrhages in some, and congestion of the liver and kidneys. Failure of the blood to clot was also observed. One of the three guinea pigs which died following exposure showed severe fatty infiltration of the liver. Survivors sacrificed two weeks after exposure showed little difference from the control animals. Pulmonary congestion was still evident but liver and kidney congestion was not References 1, Danxioch, H.: Acridenul Poworun* by Vinyl Chloride: Re port of Two Ca*"!, Canarian Med. Attoc, J. if: 833 (April 1960V 2, Pattt F. A.. W, P. Yant, and C. P. Waite: Acute Rcdpoomi of Guinn Pifa to Vmjtora of ?ome New Commercial Organic Compound* V. Vinyl Chloride, Pub. Hoallb lie pi, +3; 1963 CAufujt 1930). 3, Peoples, A. S., and C- D, Lzaxe: The Aoeethetie Action of Vinyl Chloride, J. Piomowfotf* id; 23-1 (1S33). 4, Lehmann, K. B, 3t F. Flcat; Toticniogj and Hffin\* of /nriutriof ScleenH, TmoeUced by E. Hint end H. F. Smith, Jr., WlDioma 3b VSIlkifW. Baltimore (1643). 3. ScaaciaAhXX, O.: Cited by Lehmann, K. B. and F. Flury. 6. OaTEJt, R, H., C. J. Ca&x, J. C. Kunti, and 1L J. SaDzb- wald: Aneetbaia XXVII. Narcosis with Vinyl Chloride, AneHherioloot $; 259 (1917). 7, Cam, J., R, M. BtmornoN, J, F. Vulha, and J. C. Kaantx J*.: Anesthenia XXTV*. Chemical Constitution of Hydro carbons and Cardiac Automaridty, J. Fiorm. nod xper, TWp. *7; l (1949). 5, Annual Report of the Chief Irupe&or *f F&cur-ie* for tXe Ymr mi. London : H.M.S.O. Cmd_ 3773 (lUroh 1953). 9, Habrib, D. K.: Health Problems in the Hanuiacture and Use of Pbatics, Snl. J, Ind, .tied, ;0:233 (1953). 10. Filatova, U. S., and E- S. Gaonboedo: Hyzienic Working Conditions in Polyvinyl Chloride Tar Float*, Gifirna pp. 38--42 (January 1057). Abvtrmetad in Abot. tf World Med, tM; 60 (July 1957). R&S 136095 AIHABack Issues op Quarterly "C\)R 18 YEARS THE AIHA. QU.ARTERLY was the publication of AIHA., then in 1958 it was changed to be the AIHA Journal with six issues per year instead of four. Now limitation of storage space is forcing us to dispose of all hack issues of the Quarterly. 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