Document M4Zj2Ly53pK2dZjjvMB35va19

1 i^^P-ray Diffraction I) and Dispersion Stainlination of Quartz in >c. J. /7:532 (1955). C. Karr, Jr.: Quanti* nent Determination of Anal. Client. 40:358 and M. Pusset: w Materials and Ceiffraction. Ind. Ceram. f Free Silica in Respiralines, I.C. 8521. rhe Variable Inversion am. Soc. 41:532 Inhalation Hazards >ust Concept and the of Selective Sampling. :ical Aspects of PneuCeram Soc. 32:1 >ratory Trials on the Dusts of Respirable 956). talline Silica: Criteria Dept. HEW, 0`^^Vase Control, 19lW ky: Dust Conditions mer. lnd. Hyg. Assoc. The Determination ' Ther. Anal. 4.169 he Determination of ' J. hid. Hyg. Toxicol. trtz Dust in the ared Spectroscopy, 9 (1960). mical Substances and >om Environmnt 72, American Conf. ygienists, P.Q. Box October, 1975 A mail-out questionnaire examined symptoms previously associated with vinyl chloride exposure. Assessment of exposure levels was made by analytical measurement and observation. I The resulting statistical analysis revealed a dose-response type of relationship between exposure and certain morbidity symptoms. The association of vinyl chloride exposures with morbidity symptoms ROBERT SPIRTAS. M.S., ANTHONY J. McMICHAEL, M.D., Ph.D., JOHN GAMBLE, Ph.D. and MARK VAN ERT, Ph.D. Occupational Health Studies Group, University of North Carolina, Chapel Hill, North Carolina Introduction Before its recent implication in the etiology of angiosarcoma, vinyl chloride (VC) had been given a relatively clean bill of health. First synthesized in 1833, VC has come into in creased use since World War II in the produc tion of polyvinyl chloride (PVC) resins. Until 1960, no industrial fatalities associated with VC use had been reported. However, two fatalities then occurred in a PVC polymeriza tion plant--one worker died cleaning out a polymerization vessel, and the other while working in a pit.1 These two deaths under scored the potential seriousness of the acute effects of VC upon the central nervous system. Relatively few effects have been reported as a result of acute exposure to VC. Lehmann and Flury2 reported that VC was highly nar cotic, but had a wide margin between its nar cotic and lethal concentrations. Its local irritat ing effect, however, was described as very slight. It was estimated that VC concentrations of 7-10 percent in air (70,000-100,000 ppm) would be narcotic to humans in a short time. Mr. Spirtas is a candidate for the Dr. P. H. degree in Biostatistics at the Uni versity of North Carolina. He has been a biostatisti cian with the Occupational Health Studies Group since 1972 and has had prior experience with the Na tional Air Pollution Control Administration, He is cur rently serving on subcom mittees of the Intersociety Commitee and the ASTM. Dr. McMichael is an Assist ant Professor of Epidemiol ogy at the University of North Carolina. His recent research has focussed on work-related health haz ards, particularly cancer mortality excesses, within the rubber industry. His previous doctoral research, carried out in Australia, was in the field of social epidemiology and mental health, Dr. Gamble holds a M.A, degree in Biology from Oberhn College, and an M.S.P.H. and Ph.D. in In dustrial Hygiene and Tox icology from the University Of North Carolina at Chapel Hill. His doctoral research was an environmental-epi demiologic study of respi ratory function and symp toms in selected rubber workers. Dr. Van Ert is currently serving as an industrial hygienist and laboratory di rector for the Occupational Health Studies Group in Chapel Hill. Dr. Van Ert did his graduate work at the University of North Car olina at Chapel Hill and holds a Master of Science in environmental chemistry and biology and a Ph.D. in industrial hygiene and tox icology. American Industrial Hygiene Association journal EC- 0681 779 Two cases of VC gassing were reported in Great Britain.3 A process worker, standing outside a polymerization vessel and washing it with a water stream, suddenly collapsed across the open manhole. Subsequently, he experienced tightness of the chest, nausea, abdominal pain and headache. The second case, a maintenance worker, was overcome while repairing a VC leak. A study of clinical manifestations of 186 male PVC workers identified the presence of the "narcotic syndrome", asthenic nervous symptoms, Raynaud's syndrome and hepato megaly.4 However, the absence of a control (unexposed) population, or of comparisons between PVC workers experiencing different exposures, hampered the interpretation of these findings. On studies of VC as a possible anesthetic agent, using dogs as subjects, incoordinated muscular activity of the extremities and serious cardiac arrythmias were observed.5 Angioneurosis (spasm of peripheral blood vessels) in PVC polymerization workers has also been reported.6 The association of vascular spasms (manifested as Raynaud's phemonenon) with acroosteolysis has been reported by several investigators.7'8 The pathogenesis of these peripheral vascular manifestations has been variously interpreted as disordered vasomotor control via the hypothalamus,4 as a general central nervous system dysfunction,9 or by localized physico-chemical action in conjunc tion with specific individual susceptibility.7 Overall, the literature of the recent dec ades has suggested that most of the toxic effects of exposure to VC act via the central nervous system occurring most obviously at very high exposure concentration, and that both acute and chronic toxic effects occur. A recent cross-sectional health survey of 354 VC workers related the proportion of workers who had experienced acute central nervous system symptoms at work (headache, light-headedness, dizziness and loss of con sciousness) with their duration of employ ment.10 Although a dose-response relationship was implied in the report, this relationship could be partly or wholly explained by differ ences between the several employment-duration categories either in age or in duration of opportunity to experience these acute symptoms. Methods In 1974. a mail questionnaire survey was con ducted on a population of VC polymerization workers, seeking information about the fre quency of occurrence of job-related symptoms. These self-reported symptoms were related, by the respondent, to the specific type of job he was engaged in within the polymerization plant, and to the calendar year of their occur rence, (See Appendix 1.) Further, equivalent information was collected, in identical fashion, from a sample of rubber workers in the adjoin ing plant. (See Appendix 2.) These two aspects of the study allowed internal compari sons between polymerization workers in different jobs and at different time-periods (i.e., different exposure situations), and also an external (in the sense of vinyl chloride exposure) comparison of polymeriza tion workers with rubber workers. In this way, the frequency of self-reported symptoms could be more meaningfully interpreted. The validity of self-reported work history information has been tested in another study being done on the workers in this plant and found to be accept able. In the previous study, a sample of work ers were asked to indicate the dates and job titles for all jobs held. This information was compared with company work histories. The results showed that workers were able to recall most jobs they had had and that their memory as to dates was fairly reliable within the last ten year period, but worsened in trying to go back further than ten years. Information was sought on the frequency ) of eight symptoms. The first four (dizziness or light-headedness, passing out, nausea or "sick feeling" and headache) were symptoms of central nervous system disturbance, similar to those examined in the study of Lilis, et al.10 The next two sought symptom information for peripheral neurovascular and neuromuscular disturbance ("pins and needles" and muscle weakness). The seventh symptom referred to local irritation (of eyes, nose and throat), and the eighth symptom referred to the generalized asthenia ("run-down" feeling) originally reported by Suciu et al.4 ----- Questionnaires were mailed to all workers involved in the vinyl chloride plant, and to a sample of the workers in the adjoining rubber plant. The latter population consisted predom inantly of rubber workers, with a small minor ity (five percent) of polyvinyl chloride (PVC) fabrication workers. The statistical sampling 780 October, 1975 SUPPLES! The company has have worked In cent evidence s be health hazar experiences dur 1. Clock Card Numt 2. List the main t Dent. No. (Example: 093 a. . .013. . b. . . Q93. . c. . . 093. . d. . .093 . e. . .09$ . 3. If you experier related to wort For each symptc Symptom Dizziness, light headedness Passing out Nausea, "sick" fee Headache "Pins and needles" in arms or legs Muscle weakness Irritation of eyes nose or throat General fatigue, "run-down" feeling Other symptom: A. If you underwe on the reverse diagnosis or e relationship c PLEASE BE SURE TO American Industrial Hygiene EC- 0682 >nnaire survey was conof VC polymerization nation about the fref job-related symptoms, iptoms were related, le specific type of job ;n the polymerization ar year of their occur-) Further, equivalent ed, in identical fashion, ' workers in the adjoindix 2.) These two wed internal compariation workers in erent time-periods situations), and ie sense of vinyl orison of polymeriza workers. In this way, orted symptoms could erpreted. The validity tory information has idy being done on the found to be accepty, a sample of work- the dates and job is|^^mation was w^Wiistories. The ts were able to recall id that their memory ible within the last ned in trying to go s. jht on the frequency st four (dizziness or >ut, nausea or "sick :re symptoms of turbance, similar to y of Lilis, etal.w tom information for nd neuromuscular dies" and muscle mptom referred to se and throat), and d to the generalized ng) originally 'ailed to all workers 'e plant, and to a adjoining rubber consisted predomith a small minoryl chloride (PVC) tistigal sampling October, 1975 SUPPLEMENTARY QUESTIONNAIRE: CHEMICALS (RESIN) DIVISION The company has provided Che univAeprpseitnydiwx i1th the names of all persons who have worked in the chemicals division (i.e. depcs. 093, 836 or 733). Re cent evidence suggests that some chemicals involved in PVC manufacture may he health hazards. We would therefore like to ask you about your health experiences during your employment in that area. j || 1. Clock Card Number ................................................. ,........................ 2. List the main types of lob that you have done in the chemicals division; Type of lob Time -p--e--r1iond't Dept. No. Example; 093 . . .<?93. . . .093. . e.g. Dryer operator ` .0. . ;S*rvica* + Utiliju .1. .l)ruee. e.g. 1954-59) .. jg<p$............... .. .m$........ Ifyb............... . . . 093. . i. . ,0?3 , . .9. JO.U.1 ne ,3\^eJttEinh+fJiBvlJ iQUrW . ;;: mi**.. . .093. . V? I -r . ,- If you experienced any illness or adverse health effects that might have been related to working in any of these above Jobs, please describe the symptoms. For each symptom that you experienced, record an answer in Columns A and B. Symptom '`* In which one of the above jobs did this symptom occur most? (Circle one letter to identify the job, as listed by you in Question 2.) *B* . WHonwu oofftteenn did the symptom occur? Once Occasionally Often Dizziness, light headedness Passing out Nausea, "sick" feeling Headache "Pins and needles" In arms or legs Q' c <0 0 CP 0 () 2 o Muscle weakness Irritation of eyes, nose or throat General fatigue, "run-down" feeling b 00 0 CD 0 0 Other symptom: ,<3< -j) . 4...,......I..f.....y..o..u....u...n..d..e...r.w...e...n..t...m...edical aexaminbation cfor an,,y of these symptoms, please describe, on the reverse side of this page, the following: medical tests carried out, diagnosis or explanation given to you, type of treatment, any known or suspected relationship of symptoms to factors in your work environment. PLEASE BE SURE TO ENCLOSE THIS PACE ALSO, WHEN RETURNING THE MAIN QUESTIONNAIRE. industrial Hrt.ene Associat.cn Journal EC- 0683 781 SUPPLEMENTARY QUESTIONNAIRE: OTHER TYPES OF SYMPTOMS Appendix 2 Recent evidence within the PVC-manufacturing industry has emphasized the potential health hazards of exposure to chemicals in the work environment. In order to conduct an initial survey of adverse health effects due to chemical exposure, we are asking a sample of workers to answer these extra questions, in addition to the main questionnaire. 1. Clock Card Number 2. List the main types of lobs that you have done while employed in the work areas that you recorded on page 5 of the main questionnaire: Dept. No. (Example: 115 Type of job e.g. Warm-up millman Time period e.g. 1954-59} a. . not.. . .0jsMcdaU lyfabrCpf. b. . //a*.. c. . . . . OxwpQt&ubtJ............... ............. 7/ r 7$. d e. 3. If you experienced any illness or adverse health effects that might have been related to working in any of these above jobs, please describe the symptoms. For each symptom that you experienced, record an anwer in Columns A and B. Symptom Dizziness, light headedness A. In which one of the above lobs did this symptom occur most? (Circle one letter to identify the job, as listed by you in Question 2.) Oa b de B. How often did the symptom occur? Once Occasionally Often 10 3 Passing out Nausea, "sick" feeling Headache abc a b 0o c de de de 12 02 12 3 3 "Pins and needles" in arms and legs abc de 12 3 Muscle weakness a b de 1O 3 Irritation of eyes, nose or throat 00 c de 12 0 General fatigue, "run-down" feeling Other symptom: 0a b de 1 3 ab c de 12 ................................................. a b c de 12 4. If you underwent medical examination for any of these symptoms, please describe, on the reverse side of this page, the following: medical tests carried out, diagnosis or explanation given to you, type of treatment, any known or suspected relationship of symptoms to factors in your work environment. 3 3 &g.g_2i,I2.iI;2ii-IIi.gSg.&gx_HffE^5g!yiWTO_IHg-MAiN_QUESTigNNATRE^ October, 197b Liquid Monomer V.C. E Polymerize mix with copolymer E E E \ l j ( ) Dene i Figure 1 - Schematic i r i procedure for choo > to include in the stu : tematic one-in-twel i starting place from j thereby assuring a t : the rubber plant wo j current vinyl chlori | (67%) while the r: } plant workers was ( ,, ference in response : adverse publicity oi In order to ev; ; ences of each workI reported on the qut | into 12 categories ( { pies and procedure |[Jk American Industrial Kygien zed the potential In order to al exposure, ve n addition to 1111 the work areas Time period g. 1954-59) NMr <et. Hr 7$. 11 have been ' symptoms. A and B. w often did the rnptom occur? Often 3 23 23 2 23 Q3 2 0 0 3 2 2 *se describe, tied out, or suspected 3 3 onnaire, ' October, 1975 Liquid Monomer V.C. High (N-226) Polymerize mix with copolymer Low (N=245) Control (N=227) (10) Service & Utility (06) Trucking, Loading (H) Maintenance (07) ( ) Denotes O.T. from Table I. Figure 1 - Schematic flow diagram of vinyl chloride polymerization. procedure for choosing which rubber workers to include in the study entailed taking a sys tematic one-in-twelve sample with a random starting place from an alphabetical listing, thereby assuring a representative sample of the rubber plant workers. The response rate for current vinyl chloride workers was 200/298 (67% ) while the rate for the current rubber plant workers was 89/212 (42%). This dif ference in response rates may be due to the adverse publicity on vinyl chloride exposure. In order to evaluate the exposure experi ences of each worker, the individual jobs reported on the questionnaire were grouped into 12 categories (sec Figure 1). The princi ples and procedures of regrouping production- oriented categories into health-oriented cate gories has been recently described.11 Industrial hygiene analytic sampling re sults are present in Tables I, II and III. Table I is based upon data taken by company personnel before major changes were made in controlling levels of vinyl chloride exposure, and should be representative of the relative levels that workers were exposed to during their earlier work history. Table II is based upon company data taken during the installation of environ mental controls. Table III contains data taken by University of North Carolina personnel in 1975, after major environmental controls had been installed. By comparing these three tables, it can be seen that the absolute levels of vinyl American industrial Hygiene Association Journal EC- 0685 783 TABLE I tially confounding effect of other chemicals VC Exposure Index should be accounted for. Thus, if rubber work Company Data Grab Sample-Gas Chromatograph (Prior to 1974) ers, for example, had more headaches because of solvent exposure, the effect would be to lessen the chances of a dose-response pattern O.T. DESCRIPTION EXPOSURE INDEX (as defined in the study) emerging. The ma 01 Tank Farm Operators 03 Reactor Operators 04 High Pressure H.O H H jority of workers spent time in more than one H exposure category. In addition, within the VC 05 Stripper Operators 08 Relief Operators H H plant, the respondents had no knowledge of 06 Supply Men 06 Service & Utility 02 Janitors H which exposure category they worked in. Thus, M M many of the workers served as "controls" on 07 Maintenance ? Pilot Plant Janitor 09 Centrifuge Operators M themselves for different jobs, and in addition, M L some of the VC workers will serve essentially 09 Dryer Operators 09 Bagger Operators L L as "controls" on other vinyl chloride workers. it Truck Operators L It is possible that no real difference in symp (U Low 0-50 ppm (M) Medium 50-200 ppm (H) High 200 & Above toms existed and the workers who answered the questionnaire gave biased answers because chloride have decreased, yet the gradient of exposure between job categories appears to have remained the same. Based on these sampling results, and on general industrial hygiene evaluation of the plant operation, it was possible to create a of their apprehension of working with vinyl chloride. Because of the internal consistency of the results as well as the external consistency with the findings in previous studies, this possibility is unlikely. Results ^ further grouping of the 12 occupational cate gories in Figure 1 into three exposure cate gories representing high, low, and essentially 0 Since the symptoms under consideration are all transitory and reversible, an acute effects model has been employed. Thus, each reported no exposuie to VC. Figure 1 illustrates this grouping in the context of a flow diagram of the vinyl chloride manufacturing process. person-job held, rather than each person, is __ treated as the unit of observation. Each person has been able to contribute to the analysis his By defining three exposure categories as experience in more than one job (the average noted, several purposes were achieved. If, in is approximately three jobs per person, and fact, VC exposure was causative for some or often a person has experienced jobs in more all of the given symptoms, then it would be than one O.T. group). By treating the job as natural to expect a dose-response type of the unit of observation, there is a tendency to pattern between exposure categories and symp dampen the effect of individual variability in tom response. Because of the way exposure symptom experience since workers are often categories subdivide the population, any poten acting, in effect, as their own controls. Any TABLE II Exposure Data For VC and PVC Workers in a VC and PVC Plant Company Data (Second quarter 1974) O.T, 01 04 03 oe 06 03 11 08 09 09 09 11 07 OTG High High High Low High High Low Low Low Low Low Low High VINYL CHLORIDE MONOMER EXPOSURE WORKERS HIGH EXPOSURE (most readings--20-30 ppm) 3 Tank Farm Attendant 6 High Pressure Water Cleaner MEDIUM EXPOSURE most readings--*10-20 ppm 10 Reactor Operator--Bldg. 2 9 Relief Operator--Bldg. 2 36 Service Utility LOW EXPOSURE most readings--0-10 ppm 4 Reactor Operator--Bldg. 1 12 Shipping Operator 3 Relief Operator--Bldg. 1 12 Centrifuge Operators 4 Dryer Operators 8 Baggers 9 Truckers 48 Maintenance MAXIMUM READING <40 >50 >50 50 >50 <20 <30 <20 <40 <40 <10 <10 >50 l I ? I I f f t i i 5 O.T. 03.04 L BUIt R 05 s. 08 R 09 s D 09 B 09 B <F 02 T 02 P BUI 03 R 05 S 08 F 07 l F RUf 10 F 12 G (1) Air-suppb (2) Personnel (3) Not brea Definitions f Charcoal Tub gas chroma Grab Samples injecting po Data obtair Kliran Infra-F Lower detect. Area sampl Indicator Tut Easy to re; . JJ ! of other chemicals Thus, if rubber workre headaches because ffect would be to ise-response pattern emerging. The ma ne in more than one Jition, within the VC d no knowledge of they worked in. Thus, ed as "controls" on ibs, and in addition, vill serve essentially yl chloride workers, difference in symp:ers who answered sed answers because orking with vinyl \ternal consistency ; external consistency us studies, this consideration are all n acute effects each reported n^Hperson, is /anon. Each person to the analysis his e job (the average per person, and ced jobs in more reating the job as e is a tendency to lual variability in vorkers are often n controls. Any XIMUM READING <40 >50 >50 50 >50 <20 <30 <20 <40 <40 <10 <10 October, 1975 3.T. 03.04 TABLE III Vinyl Chloride Sampling Results Chemical Plant (Buildings I & II) and Rubber Plant <3-24 to 3-26-75) VINYL CHLORIDE LEVELS (PPM) AS DETECTED BY:* location MIRAN V.C. INDICATOR GRAB SAMPLE CHARCOAL TUBE________ BY G.C. TUBE BUILDING I Reactor Room Operator's Desk Desk Cluster (4 tubes) Mezzamne General Room Typical Peak 152 155 21 2 152 93 2 20 5-6 4-5 ' _ -- 11.7 7.0. 11.7, 10.9. 7.4 47.4 11.7 Stripper Area Operator's Desk (PVC 4. CoPolymer Side) General Area Relief Area Operator's Desk General Area 33 5 24-32 28-36 24 7 _ 3_ -- 20.0 1.43 Second Floor Spray Driers General Room 09 Sagging Area Lines 4,6,7 9-163 ---- 09 Bulk Drying Area (Rotary Driers) Panel Board Area Bagger. Line 13 1.5 3.5 3_ 6.1 02 Transfer Pump House No Pumping of V.C. Pumping of V.C. 02 Purification Room BUILDING II 03 Reactor Room Operator 11 $_ 20 i. 5.8 300"> 26.1 5.2l!l 05 Stripper Level Operator 8.8`=> 08 Relief Area Operator 5.0 07 Maintenance Pipe Fitter -- -- 5.9l;> RUBBER PLANT 10 Film and Sheeting Mezzanine Area Banbury MUI *4 Area 12 General Room 1.8--4.0 3.2-6.5 Not Detectable 10,M 5.0' (1) Ajf-wipplied respirator required. (2) Personnel sample t.t) Not breathing zone CDhearficnoiatiol nTsubteorSVa.mCp.leAsn, aglyatsic*alanTdecvhanpiqoursesadsorbed to activated charcoal and subsequently analyzed hj Grgaabs Scahmropmlea*t:oggarasepshyanbdy vOaHpoSrGs dlraabwonraitnotroy spaemrspolninngelb; orettlfelesc,tbtoimttleeswsecigahleedd, aanvedracgoenstents analyzed by injecting portion <>f contents into gas sampling port of AID portable gas chromatograph. Data obtained in field low due to V.C. loss from sampling bottles. Miran infra-Kul Analyzer; continuous momtormg of V.C. by the direct reading instrument. Lower detectable limit of instrument; f>pn>. Area samples rmmroum of >1) minutes Indicator Tube.*: la*ice indicator tubes with range of 0.M4 tl ppm. i imKai methods (i.e.. charcoal tubes and Miran). Amenta" InduUnel Hyeien* Association Journal EC- 0687 785 differences found with this type of model can then be more easily ascribed to real differences in environmental exposure. Tables IV-1 through IV-8 present the basic data used in the analysis. Limiting the statistical analysis to white males (who make up 95 percent of the plant population) was necessary in order to provide adequate cell sizes. In Tables IV-1 through IV-8, the cate gories of response are labelled 0, 1, 2 and 3 to correspond with the questionnaire replies as to frequency of symptoms: never, once, occasionally and often. By examining Tables IV-1 through IV-8, it can be seen that a certain type of pattern is evident for many of the symptoms. This pattern is most evident for Table IV-1 (corresponding to symptom 1). For the 255 high exposure group jobs recorded on individuals' question naires, 94 (37 percent) were reportedly asso ciated with an episode of dizziness or light headedness at least once. The comparable fig ures for the low exposure group were 28 out of 236 jobs (12 percent) and the values for the rubber worker jobs were 21 out of 214 jobs (10 percent). The purpose of presenting TABLE IV-1 Exposure Category by Frequency of Dizziness, Light-headedness O.T. GROUP NEVER ONCE High Exposure Low Exposure Rubber Worker Column Total 161 (63.1) 208 (88.1) 193 (90.2) 562 (79.7) B (3.1) 1 (0.4) 5 (2.3) 14 (2.0) Row percentage applies to Tables IV-1 through IV-s. OCCASIONALLY 72 (28.2) 25 (10.6) 14 ( 6.5) 111 (15.7) OFTEN 14 (5.5) 2 (0.8) 2 (0.9) 18 (2.6) . ROW TOTAL 255 (100-0) 236 (100.0) 214 (100.0) 705 (100.0) O.T. GROUP High Exposure Low Exposure Rubber Worker Column Total TABLE IV-2 Exposure Category by Frequency of Passing Out NEVER 244 (95.7) 231 (97.9) 212 (99.1) 687 (97.4) ONCE 8 (3.1) 3 (1.3) 2 (0.9) 13 (1.8) OCCASIONALLY 2 ( 0.8) 2 ( 0.8) 0 ( 0.0) 4 ( 0.6) OFTEN 1 (0.4) 0 (0.0) 0 (0.0) 1 (0.1) ROW TOTAL 255 (100.0) 236 (100.0) 214 (100.0) 705 (100.0) O.T. GROUP High Exposure Low Exposure Rubber Worker Column Total TABLE IV-3 Exposure Category by Frequency of Nausea, "Sick" Feeling NEVER 193 (75.7) 212 (89.8) 190 (88.8) S95 (84.4) ONCE 5 (2.0) 0 (0.0) 3 (1.4) 8 (1.1) OCCASIONALLY 42 (15.5) 20 ( 8.5) 16 ( 7.5) 78 (11.1) OFTEN 15 (5.9) 4 (1.7) 5 (2.3) 24 (3.4) ROW TOTAL 255 (100.0) 236 (100.0) 214 (100.0) 705 (100.0) OX GROUP High Exposure Low Exposure Rubber Worker Column Total TABLE IV-4 Exposure Category by Frequency of Headache NEVER 187 (73 3) 194 (82.2) 183 (85.5) 564 (80.0) ONCE 3 (12) 0 (0.0) 0 (0.0) 3 (0.4) OCCASIONALLY 42 (16.5) 30 (12.7) 25 (11.7) 97 (13.8) OFTEN 23 (9.0) 12 (5.1) 6 (2.8) 41 (5.8) ROW TOTAL 255 (100.0) 236 (100.0) 214 (100.0) 705 (100.0) October, 1975 these tables is to desc sponse for each symy importance of these r following statistical a weighting scheme wit respectively. (Forex swered "occasionally given symptom, this i twice as important as Using the Occu; Figure I, a series of s performed to determ questionnaire respon workers to their relat ox GROUF High Expos Low Expost. Rubber Wot Column Tot O.T. GROW High Expos Low Expos Rubber Wo Column To O.T. GROUf High Expo: Low Expo: Rubber Wo Column Tc O.T. GRQU High Expo Low Expos Rubber We Column Tc American Industrial Hygiene ft*'--!* .a***- Ics IV-1 through 1V-8, tain type of pattern is symptoms. This pattern eIV-1 (corresponding 255 high exposure individuals' questionwere reportedly assof dizziness or light- The comparable fige group were 28 out ) and the values for vere 21 out of 214 purpose of presenting ROW total 255 (100.0) 236 (100.0) 214 (100.0) 705 (100.0) 255 1 (100.0) 236 (100.0) 214 (100,0) 705 (100.0) ROW TOTAL 255 (100.0) 236 (100.0) 214 (100.0) 705 (100.0) ROW TOTAL 255 (100.0) 236 (100.0) 214 (loo.o) October, 1975 these tables is to describe the patterns of re sponse for each symptom. A measure of the importance of these results is given in the following statistical analysis, which employs a weighting scheme with values 0, 1, 2 and 3 respectively. (For example, if a person an swered "occasionally" to the frequency of a given symptom, this response was treated as twice as important as an answer of "once".) Using the Occupational Title Grouping in Figure 1, a series of statistical analyses were performed to determine the relationship of the questionnaire responses of these groups of workers to their relative exposures to VC. The differential exposures to VC between the three study groups account for only one of the many possible hazards. Thus, the con trols in this study must be viewed as "internal controls" who may be exposed to other chemi cal exposures. However, the consistency and strength of the results of this study in conjunc tion with similar results from previous studies, tend to confirm the suspicion that the causative agent in this study is vinyl chloride. Since questionnaire answers are recorded in categories rather than a continuum, it was therefore appropriate to use statistical analysis techniques designed for categorical data. The O.T. GROUP High Exposure Low Exposure Rubber Worker Column Total O.T* GROUP High Exposure Low Exposure Rubber Worker Column Total O.T. GROUP High Exposure Low Exposure Rubber Worker Column Total O.T. GROUP High Exposure Low Exposure Rubber Worker Column Total TABLE IV-5 Exposure Category by Frequency of "Pins and Needles" in Arms or Legs NEVER 219 (85.9) 226 (91.5) 201 (93.9) 636 (90.2) ONCE 2 (0.8) 0 (0.0) 1 (0.5) 3 (0.4) OCCASIONALLY 21 < 8.2) 12 ( 5.1) 7 ( 3.3) 40 ( 5.7) OFTEN 13 (5.1) 8 (3.4) 5 (2.3) 26 (3.7) TABLE IV-6 Exposure Category by Frequency of Muscle Weakness NEVER 211 (86.7) 224 (94.9) 194 (90.7) 639 (90.6) ONCE 6 (2.4) 0 (0.0) 2 (0.9) 8 (1.1) OCCASIONALLY 19 ( 7.5) 11 ( 4.7) 13 ( 6.1) 43 ( 6.1) OFTEN 9 (3.5) 1 (0.4) 5 (2.3) 15 (2.1) TABLE IV-7 Exposure Category by Frequency of Irritation of Eyes, Nose or Throat NEVER 166 (65.1) 158 (66.9) 159 (74.3) 483 (68.5) ONCE 2 (0.8) 1 (0.4) 0 (0.0) 3 (0 4) OCCASIONALLY 49 (19.2) 47 (19.9) 43 (20.1) 139 (19.7) OFTEN 38 (14.9) 30 (127) 12 ( 5.6) 60 (11 3) TABLE IV-8 Exposure Category by Frequency of General Fatigue, "Run-Down" Feeling NEVER 177 (69.4) 181 (76.7) 171 (79.9) 529 (75.0) ONCE 1 (0.4) 0 (0.0) 2 (0.9) 3 (0,4) OCCASIONALLY 39 (15.3) 29 (12.3) 28 (13.1) 96 (13.6) OFTEN 38 (14.9) 26 (11,0) 13 ( 6.1) 77 (10.9) ROW total 255 (loo.o) 236 (100.0) 214 (100.0) 705 (100.0) ROW TOTAL 255 (100.0) 236 (100.0) 214 (100.0) 705 (100 0) ROW TOTAL 255 (100.0) 236 (loo.o) 214 (100.0) 705 (100.0) ROW TOTAL 255 (100.0) 236 (100.0) 214 (100.0) 705 (100 0) Amenon industrial Hygiene Association Journal EC- 0689 787 TABLE V Results of Statistical Analysis of Eight Symptoms SYMPTOM 1, Dizzyness. Itghtheadedness 2. Parsing out 3. Nausea, "tick** feeling 4. Headache s. "Pins and needles" in arms and legs 6. Muscle weakness 7, Irritation of eyes, nose or throat 8, General fatigue, "run down" feeling DOSE-RESPONSE PATTERN ye* borderline yes yes yes no borderline ye* procedure used in this analysis was the Cate gorical Linear Data Model.12 (This procedure makes use of the cell proportions in a weighted least squares analysis of complex contingency tables.) The information on frequencies of re sponse in Table 1V-1 through 1V-8 was input into the categorical data computer program (LJNCAT). The statistical model is of the form: F(w) = X/3 where ir is the vector of empirical proba bilities derived from each of the frequency Tables IV-1 through IV-8 X is an arbitrarily chosen design matrix /3 is the (unknown) parameter vector. Although it is beyond the scope of this paper to discuss the statistical procedure, it is suffic ient to indicate that this approach to categorical data analysis is analagous to the General Linear Model approach13 to the statistical analysis of continuous data. The first set of analyses examined which of the symptoms, if any, exhibited a significant dose-response type of relationship with pre sumed VC exposure. A dose-response pattern was deemed to exist if the (weighted) symptom response rate for O.T. Group 1 was significant ly* greater than for O.T. Group 2 and, in addition, the response rate for O.T. Group 2 was greater than for O.T. Group 3. This takes account of both the direction and magnitude of the respective differences. It was next decided to determine the importance of age at time of exposure to each job as a possible confounding variable. The study population was subdivided by age at exposure into ^ 36 and ^ 37 at time of entry into job. For those symptoms where adjustment by age produced a better fitting model (in the statistical sense), the adjustment 'Significance here is defined as: probability of a Type 1 error (o) ^.05, for age was made in Table V. Only the statisti cal models for symptoms 1,7 and 8 were enchanccd by age adjustment. In each of these three cases age was not a significant variable in its own right, but its inclusion resulted in a better fitting model. (The direction of the dif ference in age groups for all three of these symptoms indicated that younger people tended to exhibit these symptoms more fre quently than older people, although this dif ference was not statistically significant. This may be due to a possible adaptation by older workers or to self-selection by the more sensi tive workers.) The results presented in Table V show a clear dose-response relationship for symptoms 1,3, 4, 5 and 8. This means that in addition to there being a significant difference in the re sponse rate for all VC workers when compared with rubber workers, there is a further differ ence between VC workers when they are cate gorized into high and low exposure groups. For symptoms 2 and 7, the direction of the response gradient was of a nature to indicate a dose-response pattern but the magnitude of the differences was not quite great enough to meet the criteria for statistical significance. These two symptoms have consequently been labelled as "borderline". Symptom 6 (muscle weak ness) did not exhbit a dose-response gradient. Preliminary attempts at utilizing informa tion on smoking, length of service and calendar period of exposure have yielded little to date. Further work is being done in these areas. In summary, there appears to be a doseresponse relationship between certain acute symptoms (predominantly neurological) and level of vinyl chloride exposure. The responses of the workers may have been subject to bias due to prior knowledge of the hazard of vinyl chloride exposure. However, the existance of the dose-response pattern for certain symptoms, as well as the absence of such a pattern for one symptom tend to support the validity of this study. Acknowledgment We are indebted to N in obtaining environ: discussions concernii aspects of the paper, Kuppcr for his reviev odology, to the data ; staffs of OHSG for t) behalf and to Mrs. V script preparation. S| Mr. Louis Beliczky, Hygiene, United Rul to the Corporate Me. pany under study for constructive criticisn References 1. Danzigek, H: Acci Chloride: Report o Assoc. J. 82:828 (J 2. Lehmann, K. B., F Hygiene of Industr Wilkins, Baltimore 3. Annual Report of 1 for the Year 1951. March, (1953), 4. Suciu, I., J. Drejs tions to the Study c Chloride. Mcdiciiu, l \ * t \ S t tern ble V. Only the statist!is 1, 7 and 8 were ;tment. In each of these a significant variable inclusion resulted in a he direction of the dif>r all three of these t younger people symptoms more frele, although this difeally significant. This i adaptation by older ion by the more sensi- ed in Table V show a tiot^ip for symptoms a^Bat in addition to di^Knce in the reorkers when compared re is a further differrs when they are catev exposure groups, he direction of the a nature to indicate a t the magnitude of the great enough to meet significance. These equently been labelled n 6 (muscle weak>se-response gradient, s at utilizing informaf service and calendar ieldcd little to date, te in these areas. ppears to be a doscvecn certain acute y neurological) and osure. The responses ieen subject to bias the hazard of vinyl vcr. the existancc of for certain symptoms, such a pattern for TorMke validity of October, 1975 Acknowledgment We are indebted to Mr. Earl Arp for his help in obtaining environmental samples and for discussions concerning the industrial hygiene aspects of the paper, to Professor Lawrence Kupper for his review of the statistical meth odology, to the data processing and laboratory staffs of OHSG for their steadfast efforts in our behalf and to Mrs. Wanda Dodson for manu script preparation. Special thanks are due to Mr. Louis Beliczky, Director of Industrial Hygiene, United Rubber Workers Union, and to the Corporate Medical Director of the com pany under study for their advice and constructive criticism. References 1. Danziger, H: Accidental Poisoning by Vinyl Chloride: Report of Two Cases. Canadian Med. Assoc. J. 82:828 (1960). 2. Lehmann, K. B., F. Flury: Toxicology and Hygiene of Industrial Solvents. Williams and Wilkins, Baltimore (1943). 3. Annual Report of the Chief Inspector of Factories for the Year 1951. London: HMSO Cmd. 8772, March, (1953). 4. Sucru. J.. J. Drejman, M. Valaski: Contribu tions to the Study of Affections Caused by Vinyl Chloride. Medicina Interne 75.967 (1963). 3. Oster, R. H., C. J. Carr, J. C. Krantz, M. I. Sauerwald: Anesthesia XXIV. Chemical Con tribution of Hydrocarbons and Cardiac Automaticity. J, Pliant, and Erper. Therap. 97:1 (1949). 6. Filatova, V. $., E. S. Gronsberg: Hygienic Working Conditions in Polyvinyl Chloride Tar Plants. Gigi Saint. 38 (1957). 7. Wilson, R. E., W. E. McCormick, C. F. Tatum, et al.: Occupational Acroosteolysis. JAMA. 201: 377 (1967). 8. Dinman, B. D., W. A. Cook, et al.: Occupation al Acroosteolysis. 1. An Epidemiological Study. Arch. Environ. Health. 22:61 (1971). 9. Filatova, V. S., E. S. Gronsberg. Cited in: Anghelescu, F., et al.: Clinico-Pathogenic Con siderations of Raynaud's Phenomenon in Work ers of the PVC Industry, Medicina Interna. 21: 473 (1969). 10. Lilis, R. et al.: Prevalence of disease among vinyl chloride and polyvinyl chloride workers. Paper presented to New York Academy of Sci ences Conference on Vinyl Chloride, New York, May, (1974). 11. Gamble, J. F., R. Spirtas: Job Classification and Utilization of Complete Work Histories in Occupational Epidemiology. J. Occup. Med. In press. 12. Grizzle, J. E., C. F. Starmer, G. G. Koch: Analysis of Categorical Data by Linear Models. Biom. 52:489 (1969). 13. Starmer, C. F. and J. E. Grizzle: A Computer Program for Analysis of Data by General Linear Models. Inst. Stat. Mimeo Series No. 560 (1968). American Industrial Hygiene Association Journal EC- 0691 789 American INDUSTRIAL HYGIENE ASSOCIATION OCTOBER 1975 | Subclinica! psychomotor and neuromuscular changes in workers | exposed to inorganic mercury... Performance decrements in neuromuscular functions and psychomotor skills were found to be reversbile and correlated with blood and urine mercury levels page 725 A successful respirator program... A voluntary program was implemented successfully to accomplish mandatory respirator usage in a large plant page 752 Linking industrial hygiene and health records... Historical industrial hygiene sampling data and employee health data were correlated through the personnel record system page 760 The relation of vinyl chloride exposures to morbidity symptoms... Mail-out questionnaires were used to examine symptoms associated with exposure to vinyl chloride page 779 AIHAAP 36(10)721-7(9(1979) ROBERT F COPE JR. 11123 K-AJOR OAK DRIVE BATON ROUGE LOUISIANA 70S15