Document omjxdnbOnN286DEx544Xexww7

jNTfcKNAL, CORRESPONDENCE OUS 10S7P - A # Dr. R. L. Gibson at 1600 2 Hou Ctr to Mr. F. L. Pyle at 3974 2 Hou Ctr SUBJECT: Review of Medical Reports and Medical Programs - Plastigama IN REPLY REFER TO date February 25, 1977 Ecuador -/S' A meeting was held on December 20, 1976 in my office at 2 Houston Center with Mr. Antonio Ginatta of Plastigama, Mr. S.A. Bayliss of GOCHEM and Mr. R. Clapp of the Medical Department. The primary purpose of the meeting was to review the medical records and work histories of three Plastigama workers who had reported respiratory symptoms and to evaluate these symptoms with respect to their work in blending PVC resin. Medical examinations were completed in December on all three workers by Dr. A. Serrano, a general practioner, who serves as a company medical consultant. His findings and conclusions were available for review along with brief medical examination reports by the Departamento Medico Del I.E.S.S., Medici ana Prevent!va. One of the workers was also seen by another consultant and this report was also reviewed. A summary of the findings of these medical studies which had been given to Mr. Ginatta follows: 1. Tito Muzzio: Age 34, supervisor of PVC blending and a director of the company union. Work History: 1965-1968 - PVC Department at another plastics plant 1969-1971 - Printing Department, Plastigama 1972-date - PVC Blending, Plastigama, supervisor since 1975 Government Medical Report: Medical History - negative but incomplete (October 1975) Physical Examination - not reported Laboratory Tests - serology negative, stool test positive (Ascaris 1umbricoides) Chest x-ray - negative Dr. Serrano's Medical Report: Medical History - negative except for (December 3, 1976) frequent sore throats for 3 years, improved * past 3 months Physical examination - positive findings included obesity, "chronic pharyngitis, chronic tonsillitis" and "deviation of the nasal septum" Laboratory Tests - not reported Chest x-ray (December 3, 1976) no changes when compared with chest x-ray taken on June 4, 1973 RECEIVED CUSAROSS 00123 MAR 3 1377 IH&RHP Dept 2. Victor Armaza: Age 32, PVC blender Work History: 7/70 - 10/70, Blow-molding granulator (Plastigama) 10/70 - 1/73, Pipe granulator 1/73 - 11/76, PVC blender 11/76 - date - transferred to office Government Medical Report: Medical History - negative but incomplete (November 19, 1975) Physical Examination - not reported Laboratory Tests - serology negative Chest x-ray - negative Dr. Serrano's Medical Report: (December 3, 1976) Medical History - negative except for frequent sore throats, shortness of breath during the night about three times weekly for 1% years, a weakness and numbness of his left hand during the night - duration unknown Physical Examination - Positive find ings include "chronic tonsillitis and chronic pharyngitis" Chest x-ray - done but no comment by Dr. Serrano in his report 3. Abel Briones: Age 22, PVC blender Work History: 1/73 - 6/74 - PVC pipe worker (Plastigama) 6/74 - 10/74 - PVC blender 10/74 - 6/75 - Army service 6/75 - date - PVC blender * Government Medical Report: Medical History - negative but incomplete (November 10, 1975) Physical Examination - not reported Laboratory Tests - serology negative 2 CUSAROSS 00124 Dr. Serrano's Medical Report: Medical History - Acute bronchitis (December 3, 1976) at age 7, foot fungus, sore throat of 4 months duration Physical Examination - Positive find ings include "chronic pharyngitis and chronic tonsillitis" Chest x-ray (December 3, 1976) - no changes when compared with chest x-rays taken on August 30, 1976 Dr. Hugo Coello's Medical Report: (September 24, 1976) Medical History - "Repeated bronchopulmonary processes" with productive cough (5-10 cc sputum/24 hour), low grade fever, asthenia and lack of energy for 3 years except for absence of symptoms during military service. Physical Examination: None reported Laboratory Test's: None reported Chest x-ray: "Many nodular shadows in both lung fields. Linear shadows of fibrosis appearing are small areas of focal pneumonitis in the lower lobe and both hemidiaphragms are slightly flattened". Clinical and Radiological Diagnosis: "Pulmonary fibrosis, pussy pneumon itis, emphysema, pneumoconiosis: The chest x-rays on the three workers were reviewed by Dr. R. Villarreal, a Boardcertified radiologist in Houston. Because the quality of the films varies and some are technically not satisfactory. Dr. Villarreal recommended repeat PA and lateral chest films on Tito Muzzio and Abel Briones. He noted that his findings are "very questionable". On the basis of these x-rays he cannot confirm a diag nosis of pneumoconiosis. I suggest that a repeat x-ray also be done on Victor Armaza and that all of these films again be sent here for Dr. Villarreal's review. It is my impression that Dr. Serrano's diagnoses of chronic tonsillitis and chronic pharyngitis in each of the three men and Dr. Coello's diagnosis of pulmonary fib rosis, pneumonitis, emphysema and pneumoconiosis in one of the men are not related to their work in PVC blending operations at Plastigama. While it is possible that 3 CUSAROSS 00125 high PVC dust exposures could cause mild upper respiratory tract irritation like a nuisance dust, I would not expect chronic and severe respiratory dis ease from these exposures if accurately documented. Attached is an excellent article on this subject, "Effect of Occupational and Nonoccupational Factors on the Respiratory System of Vinyl Chloride and Other Workers" which concluded that VC and PVC exposures do not constitute a significant respiratory hazard. The results are based largely on the subjective complaints and smoking histor ies of the exposed groups and emphasize the importance of objective pulmonary function tests. It points out that heavy smokers show,the most significant findings regardless of the exposure. This study appears to refute an earlier suggestion in the literature that VC may act as a lung irritant. The medical reports on the PVC blenders omitted a smoking history. At our meeting it was recommended that a diagnostician (internal medicine specialist) in Guayaquil examine groups of employees working in areas of the plant with the highest potential of chemical exposures. These groups would initially include workers in the PVC blending area and workers in the solvent and printing areas. Possibly other groups would be included later after further industrial hygiene monitoring. The instruments are now in the plant to carry out this program of environmental surveillance. As I suggested, I recommend that all three PVC blenders be included in the group to be examined although two of the men have been transferred to other jobs. This medical examination should be done annually and include the following procedures: 1. A thorough medical history documenting past medical conditions, current complaints and a detailed smoking history. 2. A complete physical examination. 3. Laboratory studies - A urinalysis with microscopic examination, a com plete blood count (hemoglobin, hematocrit, white cell count and differential), a blood chemistry test (an SMA-12 or as a minimum the following: serum bili rubin, SGOT, SGPT, alkaline phosphatase, creatinine, cholesterol). 4. A 14" x 17" PA chest x-ray (pregnant females excluded). 5. Other procedures as necessary based on the medical findings; e.g., the three workers reporting complaints should have pulmonary function tests. Attachment cc: J. Comeaux S. Bayliss A. Ginatta R. Clapp Dr. Wm. McClellan Dr. H. Miller Dr. R. Cheng 4 CUSAROSS 00126 Original Articles * COPIED BY MCA FOR DISTRIBUTION TO THE VINYL CHLORIDE TECHNICAL PANEL, NOVEMBER 11, 1976 MR. MILTON FREIFELD Effect of Occupational and ITEM 6 Journal of Occupational Medicine October 1976 Vol. 18 No. io Nonoccupational Factors on, Respiratory System of Vinyl Chloride and Other Workers John Gamble, Ph.D.; Shuguey Liu, M.S.; A. J. McMichael, M.D., Ph.D.; and Richard J. Waxweiler, M.S.I.E. There are suggestions in the literature that vinyl chloride (VC) acts as a lung irritant. Respiratory questionnaires and lung function tests were administered to 174 chemical (VC) workers, 81 polyvinyl chloride (PVC) workers, 72 former VC workers, and 136 rubber workers, and 68 maintenance workers with exposure to VC, PVC, and rubber. Except for small air ways obstruction associated with rubber, increased respiratory symptoms and decreased pulmonary function were notlj (associated with working in chemicals, plastics, or rubber^! Some increases in baseline pulmonary function were1 \ associated with VC exposure. Acute reductions in pulmonary function were observed in smokers working in chemicals, plastics, and rubber. Heavier cigarette smokers over 40 years of age had the most adversely affected respiratory system. Work was not associated with chronic respiratory effects, but all exposure groups experienced some acute respiratory insult. At high exposures, vinyl chloride (VC) is a nervous system depressant, and in fact was investigated as a possible anesthetic, but was not used because of circulatory and cardiac effects at concentrations of 10-20 vol. %.' In the late 1960's, acroosteolysis was associated with the polymerization of VC to form polyvinyl chloride (PVC).!`* Early in 1974, four fatal cases of angiosarcoma of the liver were reported in reactor operators working in a VCpolymerization plant.' Subsequently the disease has been discovered among VC workers all over the world. Experimental and epidemiologic studies suggest that exposure to VC may carry an increased risk of respiratory impairment.l,'M As a result, the Occupational Health Studies Croup 'OHSG at the University of firm Occupation*) Hp,ilth Studies Cioup, School ot Public Health. Univervtv of North Carolina. Chapel Hill NC 27514 Reprint requests to NCN8 Plaia. Suite 32, Chapel Hill. NC 27514 (Dr Camhtei North Carolina and the National Institute of Occupational Safety and Health (NlOSH) and CDC jointly carried out an epidemiologic study of VC-PVC workers A part of this study was the investiga tion of respiratory function and symptoms in currently employed VC and PVC workers, former VC workers, and a sample of control rubber workers employed in the same plant. Methods and Materials The plant under study has three major divisions. The chemical plant produces primarily polyvinyl chloride (PVC) resin, although some copolymers such as vmylidene chloride and styrenebutadiene are also produced. The polymers are either shipped or used in the Film and Sheeting division of this same plant in the production of plastic products. Film and Sheeting division (plastics) is m a building adjacent to the Chemical Plant, which also contains the Rubber Products division manufacturing primarily tires and tubes. All workers currently employed in the VC-PVC plants were invited for examination. A sample of 136 rubber workers from cleaner areas of the rubber division (i.e., tire building, final inspection, shipping and receiving) and without prior exposure to either VC or PVC, were selected and groupmatched with the VC workers on age and sex. A total of 71 former VC workers and 68 maintenance workers were also examined. The response rate varied from a low of 62% in rubber workers to 77% in chemical workers. Clinical, smoking and occupational histones, complete physical examinations, chest roentgenograms, sputum cytology, symptoms, blood and urine chemistries were obtained on all 531 workers, and will be reported elsewhere The British Medical Research Council respiratory questionnaire was administered by trained medical interviewers. Each worker performed a minimum of five forced exhalations, seated and with a noseclip The three best performances were selected on the basis of forced expiratory volume in 1 second (FEV) and forced vital capacity (FVC) within 10% of each other, and acceptable re producibility of the flow-volume curve. In addition to FEV and Journal of Occupational Medictne/Vo! 18, No. 10/0ctober 1976 659 CUSAROSS 00127 FVC expired flow at 25% (FEF25), 50% (FEFso), and 75% (FEF75) of exhaled FVC were obtained. At least three single-breath nitrogen tests were also performed. Recommended procedures and selec tion criteria were followed for obtaining closing volume (ex pressed as ratio of closing volume to vital capacity. CV/VO.11 In addition, a random sample of fifty-six VC, PVC and rubber workers were administered lung function tests before work and again after work. The difference in flow rates is calculated as after - before/mean with afterwork flow rates measured using the maxi mum pre-exposure FVC. The following questions were of interest in this study: 1. What are the effects of work on respiratory symptoms and function? Symptoms and baseline lung function were analyzed ac cording to three work exposure categories: (a) current job (hourly VC salary VC, PVC, rubber, maintenance, former chemical): (b) all jobs, past and present (only in VC, only in PVC. only in rubber, or in a combination of the three). In this mixed exposure group an analysis of covariance was used to sort out the contributions of the VC, PVC, and rubber work experience to baseline pulmonary function; (c) man-months of exposure to VC: All VC jobs were given a high (10). medium (3) or low (1) exposure rating. Time 'in months) spent in each job multiplied by the exposure index provided a cumulative exposure to VC. This cumulative exposure score (CES) was then compared to baseline pulmonary function. The association of dose (years worked in the exposure categories or CES) and baseline lung function were assessed by calculating lung function regression equations for each smoking category of the total population. Then, within each exposure group, actual values of each smoking category were expressed as a percentage of expected values for all workers in that same smoking category. In this way, the effect of work exposure on lung function was adjusted for differences in age, height and smoking between exposure categories. 2. What are the potential hazards of work exposure as measured by changes in pulmonary function over a work shift (APF)? A reduction in lung function suggests the likelihood of some harmful exposure in the working environment. 3. Are symptoms rates and lung function parameters com parable to Other occupation groups? Because the PVC and rubber control groups were themselves exposed to varied levels of dust and fumes, comparisons with other studies are made Results The age-smoking distribution of the population is shown in Table 1. Slightly over half of the population were smokers, 20% nonsmokers, and 16% exsmokers. The exsmdkers were older than the other smoking categories, with proportionally fewer ex smokers in the <.39 year age group. Smokers and nonsmokers had approximately the same distribution in all age groups, although a higher proportion of nonsmokers were older, and a higher proportion of smokers were in the middle age groups. None of the light smokers (<1 pack/day) smoked more than 25 pack-years, and they were equally distributed in the < 25 pack-years category. Most (61%) of the heavy smokers < .1 pack/day) were in the > 25 pack-year category; 25% smoked 10-25 pack-vears, and 14% < 10 pack-years. Table 2 shows the distribution of symptoms related to smoking and age. Prevalence of cough, phlegm, and persistent cough and phlegm did not increase with age. Breathlessness increased slightly but steadily with age. with the oldest age group reporting a rate of breathlessness 2.5 times greater than the youngest age group. Smoking had a strong effect that was dose-related for all respiratory symptoms. Light smokers ( < 1 pack/day) had the same symptom rate for cough, phlegm, and persistent cough and phlegm as exsmokers and pipe or cigar smokers. Exsmokers, pipe, cigar, and < 1 pack/day smokers had similar rates of breathlessness. Because of the potential confounding effects of age and smoking, comparison of symptoms in each exposure category were adjusted for smoking and age differences. Table 3 shows the prevalence of respiratory symptoms according to current |ob The salaried chemical workers consistently had the lowest prevalence for all symptoms. Plastics, former chemical, and maintenance workers reported the highest rates for cough, phlegm, and per sistent cough and phlegm: rubber and hourly chemical workers were intermediate for these symptoms. All workers except the salary chemical workers observed similar rates of breathlessness Table 4 reports the age and smoking ad|usted prevalence or respiratory symptoms in workers working only in the rubber division, only in plastics, and only in the chemical plant. Main tenance workers move back and forth among chemical, plastics, and rubber, with no epidemiofogically appropriate records kept of time spent in any of these areas. The mixed group comprised those who had worked in two or more exposure categories The plastics only and chemical plant only workers had marked reduc tions in reported symptoms when compared to all currently em ployed workers in these same categories. Symptom rates for the mixed group were slightly higher than observed in the total population, and similar to the former chemical group Those working only in chemical, plastics, or rubber appear to be a select group of healthier workers. A high proportion of those with symp toms in current |ob categories had a mixed exposure of rubber, chemicals and/or plastics. 660 Tibia 1. *-- Age-Smoking Composition of Study Population. Smoking StiNi Noremc*' Eismdiert Smoker t Pipe jnf Cifi/S AM Ago < 29 N (N) 26 (24 3) 8(15) 67 (62 6) 6 1 561 107 (20.2) JO-39 N (SI 19 (21 31 8 ( 90) 52 158 4) 10 (1121 >9 (168) 40-49 X IS) 27 (16 7) 29 (179) 92 (56 8) U ( 86) 162 130 6) 50-59 N (S) 27 (17 9) 35 (23 2) 75 f4Q 7) 14(9 3) 161 (28.4) 60 H (S) 9 (40 91 4 (182) 6 (27 3) 3 (136) 22 ( 4.1) Totil ft IS of Total) 108 (20 3) 84 (15 8) 292 (55 0) 47 (8 9) 631 'flcr&mdier = has smoked less than 100 cigarettes m 4 lifetime ttomaker -- has stooped imping for more than 1 year and dc*snot now smoke a pipe or cigar tSmoker - lus smoked more than 100 cigarettes m a lifetime, and has smeked within the last year Pipe or cigar smokers who also smoke cigarettes are included m this fPipe and Cigar = alt those who smoke a pit* or cigar now hutdo not smeke cigarettes or have not smoked cigarettes (or a year or more Percentages wi ttie marginal* are % of totals, percentages m cells are column percentages Occupational and Nonocaipaticnal Factors on the Respiratory System of VC Workers/Gamble e;. al CUSAROSS 001 Ttblo 2, -- Rojpintory Symptom* by Ag tnd Smoking. Smoking Category NonsmoAer Eismq* All smoAen 4 1 padi/day 1 padi/diy > 1 padk/day Pipe and Cigar Alt 4f Category i 29 30-39 4049 50-59 >60 N 103 (20.3*0 34 (15 8%) 292 (55 0%) 61 (II5V 143 126 9%) 88 (16 6%) 47 ( 8 9%) 531 107 (202%) 89 116 8%J 162 (30 5%) 151 (28 4%) 22 ( 4 1%) Coofti 182 % 56 7.1 21.6 98 189 341 85 149 140 157 15.4 146 136 Mi mm 1 82 * 83 13.1 26.4 131 23.8 39 8 10.6 192 206 157 204 185 22.7 Penitent Cough A Phtagm % 28 60 137 16 112 261 21 * 92 93 90 105 79 91 * = Scored by ffiteru from British Medcal Research Council Respiratory questionnaire f = l missing t=3 missing Braathtaurma % 11.1 19 3t 265f 23Jt 189 40.9 15 2t 2121 1251 19.1 216 26.5 318 Figures 1-6 display the regressions of pulmonary function tests for the different smoking categories. Age and height significantly affected FEV and FVC values; age, but not height, was a statistically significant predictor of flow rates and closing volume (CV/VC). Heavy smokers (l pack/dav) had markedly reduced ventilatory capacity compared to other smoking groups (except for FVC where smoking did not significantly affect lung volume). Lung function values of exsmokers decreased at a rate in termediate between the heavy Smoker and nonsmoker groups. Pipe or cigar smokers resembled nonsmokers for FEV, FEF.o, and FEFrs, but resembled exsmokers for FEFis-rs and closing volume (CV/VC). Except for CV/VC, the least reduction of ventilatory capacity was observed in the light smoker (<1 pack/day) group. All smokers had similar functional reductions of CV/VC with in creasing age. Current smoking behavior showed a better correlation with pulmonary function than did pack-years of smoking, and for this reason regressions based on current smoking categories were used in calculating predicted lung function values. Table 5 summarizes the prevalence of impaired lung function as related to age and smoking. Except for FVC and CV/VC pulmonary function impairment (see Table 5 for definitions) con sistently increased with age; and for all parameters consistently in creased with increased smoking Impairment rates for FEF js xs FEFso/FVC and CV/VC were significantly higher for smokers than nonsmoking categories; the smaller number of pipe or cigar smokers precluded them from achieving statistically significant dif ferences. Age and smoking were then analyzed simultaneously Regressions of pulmonary function with age (Figs 1-6) suggested that after about age 40, smokers of . 1 pack/day clearly had lower lung function values than the other categories of smokers. As there was little difference in prevalence of impairment among ex smokers, nonsmokers and pipe or cigar smoker categories, they were combined into a nonsmoker category, divided into age groups above and below 40 years of age, and compared with cigarette smokers. Smokers and nonsmokers in the younger age group had similar rates of lung function impairment. Smokers over Tibia 3. -- Agt ind Smoking Adjuittd Privilinca Ritot of Rupiritory Symptomi by Curront Job, Symptom Cough l and 2 Phlegm 1 and 2 Persistent Cough and Phlegm Breathlessness! (Grade 234) N Age (years) Height (m) Weight (tin) * -- \ missing t = 3 musing Rubbw % 103 151 59 20 6136 40 4 (12 S) 695 1 2 If 174 9 (23 3)* PImiIc* *. 209 261 133 221 11 44 1 (13 8) 692 ( 2 5) 160 8 (27 31 Hourly \ 148 155 Ctiwniol Silny % 8.7 84 S3 35 21 6 124 419 (12 81 15` 50 36 5 ( 8 9) 695 ( 22) 69 6 ( 2 96) 184 5 (30 71 177 4 125 IV Form* dumtci1 % 155 259 114 26 9' 72 43.1 (10 7) 69 7 ( 2 8) 183 9 (27 5) Mttnuntfta % 16.5 22.3 13.7 19 4 68 46.7 (10 2) 69 4 t 2 81 186 1 (24 6) AH % 156 19 2 92 21 24 531 42 1 (123) 69 5 (2 51 1810 (26 9) Journal of Occupational Medicme/Vol 18, No 10/0ctober 1976 CUSAROSS 00129 661 * 104i--tot< twi) 1 3 14luukar ( * ) 2*0bUr* (all) 1 47 41f*<fc/ 4H p*cktAmf 4M tl**' Wl ) *i tt------tK414)47a....r4404440c214944)a7144171nc <**-------6400000<7.,....00000,002122272111444) ''** *i p*ch/4r V (fwflhf ga larHaat 6* . Ill 47 274* . 47 2)1* . 42 14* . * 6 1)4* 0,114* 47* . Iff S.t t. 0.174 00..4>4240 B .......4477441141022$ 1 * Ai 1 A *** 1 M 1 ij T 40 1 ' 1 jo ' ^S) " * * Fig 1, -- Prediction Equations for FVC In Total Population by Smoking. 40 years of age had significantly increased impairment compared to their nonsmoking counterparts. A synergistic effect of age and smoking was not observed for FVC (impairment was not affected by age or smoking) and CV/VC (both young and old smokers had rates of impairment higher than nonsmokers at any age). To preclude confounding effects of age, height, and smoking in assessing the importance of occupational exposure, mean percent pulmonary function for each job group was calculated by dividing individual pulmonary function values by predicted values derived from the appropriate smoking category, and calculating the mean. Smoking-adjusted impairment rates were directly adjusted Fl| 2. -- Prediction Equation* for FEVi in Total Population by Smoking using the smoking distribution of the standard (total) population Baseline lung function as measured by mean percent predicted was the same in all current job groups. Table 6 summarizes the prevalence of impaired pulmonary function by current |ob Fomier chemical workers tended to have the highest impairment, salarv chemical workers the lowest. The other job categories generally had impairment rates between these extremes The effect of duration of exposure on lung function was then analyzed. Age, height, and smoking variables were ad|usted in the manner previously described. Predictive equations were Symptom Cough 1 inJ 2 Ptitegm I ind 2 Persistent Cwgh ind Phlegm SrutMessnessf (Gride 2, 3 4) N Age (years) Height (a) Weight libs) * = 1 milling t = 3 missing 662 Tbl 4. -- A(t and Smoking AdjutUd Pravalanc* Ratal of Ruplratory Symptom* by Eipoturt Catejorlei. Mirtd % 202 216 112 27 4" 217 44 7 1110) 69 3 (2 6) 184 9 (29 41 ftubtae Only *. 10J 15.4 64 213* 132 401 (12 8) "695 (21) 175 2 (23 0)* Enpoun Ciliyofy Plattla Only Hourty % 84 28 12.9 95 Chmfc*l Only StHry % 82 7.9 25 20 20 121 28 416 (15.2) 66 44 34 7 114 3) 19* 42 36.1 (9 01 700 (2 4) 69 8 (1 9) 69 7 12 7) 180 4 (25 9) 1753 (2661 176 2 (25 81* All % 156 192 92 2! 1 531 42 1 112 3) 69 5 !2 5I 181 0 (26 9) Occupational and Nonoccupational Factors on the Respiratory System of VC Workers/Gamble et al CUSAROSS 00130 /l / /1 //' ,, //' //" /// /// // A/////// A/ / // X // / '/-S AA AA '/// t/s* 4 \ l pM+tc\W.u*^i.r Pt** *r < L**f *20, W 1,01 1.14 o,)4 *11l,-4ilJ*1 '1 ( It* r*f> *0 )t <4 )6 4 41 4.41 40((11 *4 )l 1 (hal|M _tn j o.>* J J- S U>S. as. iet o0,. i1s44: o m0. 14) 0,,1i2n4 0.202 fjj 5 __ Prediction Equations tor FEFrs in Total Population by Smoking. Fig 6. --Prediction Equations for Closing Volume/Vital Capacity CCV/VC) in Total Population by Smoking. calculated using length of work in years as the independent vari able, i.e., predicted pulmonary function = % predicted + % change in pulmonary function/year spent in exposure category. Table 7 summarizes regression for which a significant change oc curred. For exposure category 1 (rubber only, chemical only, plastics only), rubber workers observed a significant decrease of -0.8%/year in FEFzs, plastics workers a decrease of -1%/year All Other significant changes were increases in lung function. Health-related selective migration of workers is a potential source of bias m a cross-sectional study. In an attempt to take ac count of this, the effects of working in rubber and chemical, rub ber and plastics, chemical and plastics, rubber, chemical, and plastics, or any one alone, were examined by analysis of covariance (Table 7). By backwards elimination method, exposure variables not statistically significant fp > 0.05) were sequentially re moved until only the most significant exposure variables remained m the model. The analysis was done first on the total population (No 2). then on the mixed exposure group (No. 3) and finally on the combination of categories within the mixed exposure group (Nos 4-6) for the total population, working in chemicals was as sociated with increased FEV, FEFzs-rs, FEFts. and FEFso. The only re ductions m ventilatory capacity were observed in FEFrs. a highly significant reduction associated with rubber, and increased CVA/C, a functional decrease associated with plastics. The analysis of the mixed exposure groups (exposure categories 3-6) tended to support the results observed in the total population Pufcnonlry Function H FEV/FVC FVC FEfJi FEFMzFVC FEF/S/FVC cv.-vp Table 6. -- Ago and Smoking Adjusted Prevalence of Impaired Pulmonary Function* by Current Job. Rubber 136 113*4 74 159 126 46 4 6 2` Ptntka 81 32 5% 132 137 11 7 42 4 IZ.l' 0 Current Job Chemical Hearty Sitary 124 31 4% 64 133 62 46 7 138 50 29 7% 0 14 1 0 33 6 36 Former Chemical 72 42 0*0 85 25 2 14 4 54 4 12 6* Maintenance 68 314*4 10 1 129 79 45 6 70* Aft 531 38 2*o 81 149 10 2 475 10 5 664 `Definition of Impaired PF m Table 5 1 = 1 missing 2=2 missing 6 = 6 missing 9=9 missing Occupational and Nonoccupational Factors on the Respiratory System of VC Workers/Gamble et al CUSAROSS 00132 Table 7. -- Selected Prediction Regressions for Pulmonary Function Related to Exposure, Age. Height and Smoking Adjusted. Eipotura Category* i 2 3 1 6 \ 2 4 6 1 2 3 4 6 1 2 1 1 2 3 4 5 *2 3 5 G Predicted RuVnonary function FEV = rvc FEF2S-7S FEF2S FEFSO FEF75 CV/VC % Predicted 98 4% 992 1008 93 3 98 3 S3.fi 98 0 1073 94 4 910 98 0 968 1060 948 94 0 982 1092 111.8 100 5 948 109 9 95 5 983 976 107 9 92? + % Change +0 47H i-015 4 25 +038 +0 52 +0 86 +0 33 4.94 +0 86 +0 89 +036 +035 6 85 +090 +0 99 +0 30 477 10 0 67 4 97 2 30 10 + 043 + 046 4 75 + 1,16 4Eip*jre Category 1 = Rubber Only, PVC Only. Chemical (H & 8) Only 2 = Total Population (Rubber. Chemical. PVC) 3= Mixed Eiposure (Rubber & Chemical. Plastics & Chemical. Rubber & Plastics. Rubber Chemical L Plastics) 4=Rubber l P/ashcs (N=52) 5-- Rubber 1 Chemical (H^Sfi) 6Z Rubber. Chemical & Plastics (N"61) For Eech Tear Spent In Exposure Category Salary Chemol Only Chemical Rubder PVC Only PVC Hourly Chemical Only ChemiAl Rubber Chemical Hourly Chemical Only Chemical Chemical Rubber Chemical Hourly Chemical Only Chemical Rubber Only PVC Only Rubber Rubber Rubber Rubber PVC PVC Chemical PVC p Value (or % Change 0 02 005 010 0 04 008 0.002 0 009 004 0 03 0 003 0005 010 0Q7 0 02 0 03 008 001 007 0 0001 0 008 0 004 0 04 004 009 008 0 05 Work in the chemical plant was associated primarily with in creased flow measured over mid vital capacity. Work in plastics was associated with functional reductions of from 0 4 to 1.2%/year in CV/VC. The most consistent and greatest changes were reductions of from -0.7 to 2.3%/year in expired flow rates at low lung volumes (FEF75). associated with work in rubber. Table 8 summarizes the relation of pulmonary function and cumulative exposure to vinyl chloride (see Table 8 for definition of CES-cumulative exposure score). Increasing exposure to VC in all workers ever exposed to VC was not associated with any signifi cant reduction in pulmonary function. The general tendency was for pulmonary function to improve with increasing exposure. Only reductions in FVC approached statistical significance. Dividing the group into those with current VC exposure, and those that worked in chemical or plastics in the past (former chemical) and repeating the analysis produced the same results. The relation between respiratory symptoms and baseline pulmonary function is summarized in Fig 7, All respiratory symp toms were significantly associated with reduction in expiratory flow (FEFjs-rs, FEFzs). Cough, phlegm, and persistent cough and phlegm were significantly associated with reductions in FEFso Those with cough 2, phlegm 2 and persistent cough and phlegm had reduced percent predicted CV/VC. Reduced FEFrs was asso ciated with symptoms of cough and persistent cough and phlegm In addition to baseline pulmonary function, 56 workers were Journal of Occupational Medjcme/Vol. 18. No. lQ/October 1976 tested before work and again after work. Since the workers were also taking physical exams, actual working time averaged about 4hours. As there were about twice as many smokers (82%) among chemical workers as plastics (36%) and rubber (41%i workers, acute effects were compared in cigarette smokers and all others combined (nonsmokers). Current smokers observed sigmhcant Tbl . -- Age, Height end Smokln| Adjusted Regressions of Percent Predicted Pulmonary Function In Chemical and Former Chemical Worterv (N = 196) by Cumulative Weighted Exposure* to Vinyl Chloride. Puknonary function FEV FVC FEFH 7$ FEF2S FEFso FEF7S cv/vc Intercept (% predicted) 98 9% 1008 964 960 95 9 97 5 102 4 Slope (X ehange/CES*) +0 10X 016 +0 44 +0 53 +0 35 0 43 0 34 p nlui of Sloe* 0 47 0 13 GC4 007 0 19 0 17 a 2 * CES = Qjmuiiliw nposurt score All |oOs m the chemical oUsnt tie filed !w VC rm. + is high (TWA = approximately 250 ppm), medium (TWA approximately 75 per) i tJ (TnA approximately 25 ppm) CES was calculated by multiplying months worted times i eiposure ratmg (high = 10. medium s 3. low = 1) (or that ict>, and summing over j ce-i Range =0 2877 exposure-months CUSAROSS 00133 665 asLo* ;I 2; Fvc Fig 7. -- Percent Predicted Pulmonary Function in Workers With and Without Respiratory Symptoms Adjusted by Age. Height and Smoking. reductions in both flows and volumes. Nonsmoknrs ,ib-erccd increases in FVC and peak flow, but other lung rum turn parameters decreased, significant onlv tor FEFsn (Table 9). Smokers in all job groups had reductions in ventilatory capacity, the greatest decre ment occurring in flows at low lung volumes. The reductions wc'v of the same order of magnitude for all three exposure groups, but were significant only for vinyl chloride and rubber workers. Except for reductions over the shift of FEFso and FEFzs in nonsmoking rub ber workers, ventilatory capacity of nonsmokers did not change significantly from zero. Discussion This study was stimulated by the finding of an increased inci dence of liver angiosarcoma in vinyl chloride (VC) workers. Experi mental studies, case histories, and epidemiologic studies all suggest VC acts as a lung irritant. This literature is brietly sum marized. Patty, Yant and Waite4 exposed guinea pigs for 30 minutes to 10-40% VC. The principle gross pathological effect was congestion and edema of the lungs, and hyperemia of the kidnevs and lungs. Exposure to 10% VC resulted in slight signs of lung hyperemia while hemorrhages, edema, and severe damage to the tracheal epithelium were observed at the higher concentrations in animals dying from the initial exposure. Pulmonary congestion was present after two weeks in surviving animals Lower exposures for longer time periods (50-500 ppm for six months! resulted in no change in lung weight in rats, guinea pigs, rabbits and dogs Expo sures at concentrations greater than 100 ppm produced reversible liver in|urv in the more sensitive species/ Lester, et al3 exposed rats to 20,000 ppm (2% VC) for three months, and 50 000 ppm (5% VC) for 19 days. They observed increases in liver weight and decreases in white blood cells, but concluded that the observed Table 9. -- Acute Effects (Mean % Change") in Chemical, Plastics and Rubber Workers by Smoking Categories, The hypothesis was that PF should not differ significantly from zero (H:APF = 0) The one-sided t test was used to test significance Standard deviation is in parenthesis. Currant Jab Wortrt Pintla Rubber All NS f 55 NS s NS s NS S n AFEV A FVC XX 3 153 (2 551 14 "1 fil" (2 54) -020 (219) -0 336 (2 45) 8 +04] (315) 4 3,52 (5 62) + 109 (2 61) 2.03" (154) 17 +Qi4 (4 821 10 3 33" (4 31) +0 72 (2 641 2 75" (3 02) 28 +028 +0.73 1415) (2 53) 28 2.50"" 1.44"* (3 691 (2 74) ApeF X 0 97 (E 40) -421(8 70) 2 39 (9 59) -4 05 (8 73) +3,82" (8 73) 5 70 (11 73) + 153 (910) 4 72** (9 56) A FEF2J 7 J \ +0 40 (8 87) 1006'*** i5 11) 1 93 (9 65) -4 53 (9 48) +025 (10 08) 9 72" (11 651 +0 36 19 55) -9 15**** (8 47) A FEFZ5 X + 1 63 (6 83) 9 43"** (4 87) 1 85 (8 60) 100 (1499) +0 62 (7 56) 8 30** (11 12) +0 03 17 62) 7 82*"* (927) A FEFso X 0 93 (12 43) 8 28"** (6 35) 0 53 (6 78) 11,23 (1301) 1 35 U3 99) 8 75 (15 16) *1 44 (11831 **87*"" (10 76) AFEF75 X 2 77 (15 42) 14 75*** (13 46) -4 24 (25 85) 22.76 (26 83) 5,76 12393) 1926" (22 14) 5 04 (23 05) 17 51'* ** (18 43) A CV/VC t s + 1420 (32 95) + 851 (45 19) 12 35 (25 26) + 15 10' (12 32) 0 55 (29 51) +189 (33 40) 2 34 (28 71) +7 09 (37 33) "S = < 00S "B = < 0025 "*p = < 0005 *"'p = < 0 005 tNS - wnsmoket. eismr*er, pipe or cigar sm* IS " smt*er % = A positive sign indicates a decrease m performance as the after work CV/VC ratio is larger than the before work CV/VC ratio. "Mean % change = after work PF - before work PF , mean PF -- after a- before mean PF 2 666 Occupational and Nonoccupational Factors on the Respiratory System of VC Workers/Garr,tie et al CUSAROSS 00134 lung edema and congestion could not he attributed to the irritat ing effects of VC, and the pneumonia ohservecf was probably due to secondary infection Keubler'0 exposed rats, mice, and guinea pigs to 5,000,15.000 and 25.000 ppm VC tor 2-hours a day for 100 days without observing any histological damage. In a report of a case of VC gassing in a plant in Creat Britain, a worker washing out a polymerization vessel with water collapsed and was given artifi cial respiratory. Subsequent symptoms included chest tightness.1,1 Boytsov' reports (without giving the number of species or animals, length or amount, of exposure) that inhalation and intra tracheal administration of PVC resin produced a "development of peribronchitis in the lungs" and local thickening of interalveolar septa. Two studies of PVC workers in Russia and Germany con clude that the respiratory system was affected." 12 A "consider able number" of 96 PVC workers in Russia had a "changed bronchovascular pattern and increased pulmonary ventilation at rest".11 Eight of thirteen Cerman PVC workers employed for 175 to 18 years showed partial pulmonary insufficiency with signs of predominantly restrictive changes of the lungs.'-' This latter finding is in agreement with the case described by Szende. et al.u A 31 year old male had shoveled PVC dust in a drafty place for 1-year prior to being examined for severe dyspnea. The possibility of pneumoconiosis elicited by inhalation of PVC resin was suggested. There are a number of problems with the experimental studies of animals Only at very high VC concentrations are effects ob served, and these are anatomical changes from gross pathology or histology. More sensitive functional measurements at lower, more realistic, VC exposure concentrations have not been reported. The foreign studies are only suggestive, and do not provide enough information to evaluate. There is onlv one reported epidemiologic Study of VC and PVC workers in the U S." Cough and sputum production ior most of 1year or more clinical signs of emphysema were reported in 31"'-. of the 348 currently and previously employed VC and PVC workers. Smokers and nonsmokers over 40 years of age had similar rates ot flow impairment. In the age group under 40 however, smokers had about twice the prevalence of flow impairment as nonsmokers The higher prevalence of flow impairment in smokers compared to nonsmokers converged slightly with increasing duration of exposure; nonsmokers and smokers with more than 20 years exposure had the same prevalence of flow impairment. Jhe authors conclude that the etiologic agents producing the reduced au flow m workers over 40 years of age or with > 20 years exposure is unclear but is not due to smoking. Exposure was to~VC monomer. PVC resin dust, and pollution in a heavily industrialized City: -- -- fRe effect ofQsmokingon respiratory symptoms has become common knowledge following the report of the Surgeon General on the Health Consequences of Smoking (1964) and its sub sequent supplements.17 The results of this study confirm these re ports, with the possible exception that light smokers (< Ipack.'day) in this Study resembled exsmokers more than heavier smokers (il pack/day). Pipe or cigar smokers have been less studied, although it has been suggested that pipe smokers are to be distinguished from cigar smokers." Because of small num bers this has not always been done, and in this study these smokers were combined. They generally resembled light smokers and exsmokers in both symptoms and lung function. The effects of smoking on symptoms have generally shown Cough and phlegm to be higher in smokers, with prevalence relat- Tlbl 10. -- Comparison of Rasplritory Symptom Provalanco. Population this Study (AID Nommokers Smokers Mining Community West Virginia* Norcmokers Smokers Rendon Semple. Melts Berlin N H" Nonsmoters Smckers Stratified Sample. Industrial town m Eftgbnd* Nonsmcken Smoker White, maie nonsmoMrs 35*4* NYC Postmen* Nonsmokers Smokers NYC Transit Workers* No'fSmokjrs Smokers N S31 108 292 162 613 76 172 96 653 469 903 2687 tot? 3745 Cough X 149 56 21 6 154 472 10 7 401 -- 55 70 27 0 64 23 5 Phlegm X 192 83 26 4 31 1 462 16 5 162 -- 41 131 269 95 23 7 Persistent Cough l Phlegm % 92 28 137 14 0 38 3 73 170 9,0 43.4 15 40 190 28 152 Breathlessness % 21 2` ii r 26 5` 5 Of 10 7* 381 is or 51 89 22 61 21 fit 34 0 1241 23 3 * Grade 2. 3, 4 breathlessness tGrede 3 and 4 breeihiessnesj t Grade 2 inj 1 hreithiessnesi Journal of Occupational Medicine/Vol 18, No 10/Qctober 1976 CUSAROSS 00135 667 ejl to the amount of smoking, a relationship supported by this study. Breathlessness, while generally higher in smokers, is often not related to the amount of smoking This is hypothesized as due to selective reduction of smoking m those developing symptoms of breathlessness, a more severe and disabling condition than "smokers cough"." Although movement of less fit heavy smokers into lighter smoking or nonsmoking categories seems a plausible explanation, selection docs not appear to be a strong factor in this population as there was a high prevalence of breathlessness cn the heavy smoker category. A trend for breathlessness to increase with increasing age is commonly observed," and was apparent in this study. The associ ation of cough and phlegm with increasing age has not been as consistent. Some studies report an increase with age:" 20 others (including this study) find little tendency for cough and phlegm to increase with age." 21 Two studies in West Virginia have observed an association be tween educational level and prevalence of respiratory symptoms and ventilatory lung function capacity, with the lower prevalence of symptoms partly attributed to fewer smokers in the higher educational categories.22 2 1 Stebbings-'' in 469 white male nonsmokers found no effect of social class (based on occupation, education, and income) on most respiratory symptoms; only dyspnea was significantly less common in the upper social class. Lower pulmonary function was also associated with lower socio economic status in these nonsmoking males.2' Salaried chemical workers in this study resemble the upper social class in that they smoke less than hourly workers, and are probably more educated. Exposure to VC and PVC resin is generally less than that of the hourly workers. It is not known from this study whether social class, exposure, smoking, or some combination of these factors can explain the lower symptom rates of salaried chemical workers when compared to hourly workers. The same argument applies to the slightly better pulmonary function of salaried chemical workers compared to hourly workers. Among hourly workers, no consistent or convincing differences in respiratory symptoms or function were observed. When workers were divided into exposure categories of workihg only in plastics or chemicals, the respiratory symptom rate was reduced considerably. Workers with more iob mobility were less healthy in the sense that they reported more symptoms. This coufd be due to a greater susceptibility, to having a more unfavor able job experience in terms of exposure, to self-propelled move ment to less symptom producing |obs, or some combination of these factors. Although the reasons are unknown, the fact remains that the less mobile "pure" exposure groups had lower symptom rates than control rubber workers, maintenance, and the mixed exposure workers. Are the symptom rates observed in this populatidh comparable to those in other populations? Table 10 compares the prevalence of respiratory symptoms in this study with other studies. There is considerable variation between reported symptoms in the various populations. The workers in this study compare favorably except for perhaps breathlessness. The effects of age and smoking on pulmonary function ob served in tKIs population are comparable" to other reported* studies. There were no significant statistical differences in the in tercept? of the smoking regression equations. Heavier smokers in this cross-sectional analysis had significantly greater reductions of FEV, FEFjs-75, FEFso, and FEFrs with increasing age Two points are of interest with regard to the effect of smoking Before the age of 40, smoking had no apparent effect on pulmonary function. Secondly, light smokers were obviously less affected than moder ate and heavy smokers. In the analysis of smoking, one should ex amine this dose response relation, and not arbitrarily lump to-' gether all smokers. Careful consideration of possible smoking-exposure interactions is also required. For example, in a group of workers exposed to asbestos dust, smokers reported worse lung function than nonsmokers when a single regression was used for height and age ad justment.The inference was that smoking increased tire effect of dust exposure. Using only a single regression equation for stan-, dardization is misleading however, as smokers pulmonary function decreases more rapidly than exsmokers and nonsmokers. Rossiter and Weil2' point out that an apparent synergism between dust and age may instead be a smoking-age interaction. When separate regression equations were used for standardization, i.e, one each for nonsmokers, exsmokers, and smokers, they observed no dif ference in pulmonary function related to dust exposure. In fact, the asbestos dust exposure had a more detrimental effect on nonsmokers than smokers. We know there was a smoking-age inter action in this study. Since we are primarily interested in the effect of VC exposure on pulmonary function, age and smoking ad justments were made using .the regression equations of the various smoking categories (Figs 1-6). As there was no difference in pulmonary function between current job categories, and no nonexposed group of workers was available, the regression equations used for standardization were derived from the smoking cate gories of the total population. After standardization, increasing duration of exposure in chcmicals, plastics, and rubber was not associated with large changes in pulmonary Junction. Keductions in EhErs, the most sensitive mea sure ot small airways obstruction, was consistently and significant ly associated with working in rubber: less significant reductions in FEF7S were associated with hourly chemical and plastics workers, and FVC in hourly chemical workers. Other pulmonary function parameters generally remained the same or improved with in creasing duration in chemicals or plastics, and with increasing cumulative VC exposure. The reported case of pneumoconiosis on exposure to PVC resin11 is suggestive that high exposure to PVC resin may result in a restrictive type of respiratory disease Baggers in the chemical plant are exposed to from 1-5 mg m` of particulate (measured by area Hi-volume samplers); respiratory particulate is 1/10 to 1/20 these levels. Exposure to the PVC resin in plastics appears higher for Banbury operators but lower tor workers in milling, and negligible for other plastics workers. The low prevalence of FVC impairment in both chemical and plastics workers docs not support the hypothesis of PVC resin exposure I producing volume restriction. What difference is there between the workers in this study and those reported on by Miller, et at? Pulmonary function impairment for FEV/FVC, FVC. and FEF75/FVC in this study employed the same definition as Miller, et al,14 in their study of VC-PVC workers The prevalence of impairment for FEF25-75, using the same criteria, was essentially zero, and thus far below the 53% they observed The cutoffs for impaired flow as measured by FEFso/FVC and FEF-s/FVC have been shown to be reasonably effective in distinguishing nor mal subjects from those with obstructive lung disease.12 The high est prevalence (almost 50%) of impairment was for FEF75/FVC and supports the observed association of reduced FEF> with increas ing duration ot work. All VC-PVC nonsmokers less than 40 years of age, and all workers m this study less than 40 years of age, had about a 20% prevalence of impairment for FEV/FVC and FEF75/FVC. The prevalence of impairment increased for nnn- 668 Occupational and Nonoccupational Factors on the Respiratory System of VC Workers/Gamble et al CUSAROSS 00136 smokers over 40 in both populations, but more so in the Miller study. The rates of flow impairment in both studies are the same for smokers over 40 In both studies the prevalence of impaired FVC (< 10%) is considerably lower for flow impairment (18-75%) and much lower than expected from exposure to asbestos." The association of increased pulmonary function performance with increasing exposure and work duration, particularly in chemi cals. suggests that selection is occurring in this population. The reason for the lark of association between VC exposure and respiratory effects may be due to differential migration of more susceptible workers out of chemicals. Note that the mixed expo sure group reported a higher symptom rate than chemical and rub ber workers who had never moved. The current plastics worker had symptom rates comparable to or higher than this mixed expo sure group, suggesting that net migration of "susceptibles" may have been into plastics. The association of small airways ob struction with exposure may be more informative than symptoms because (1) small airways may be more sensitive to the effects of environmental agents; and (2) small airways obstruction is probably not noticed by the individual to the same extent as symptoms and FEV reductions, and would therefore not be af fected as much by selective migration. Several conclusions emerge concerning factors that affect base line pulmonary function in this population; (1) age and smoking were the two most important factors reducing pulmonary func tion; smoking was associated with obstruction only (no significant effect on FVC). (2)-small airways function as measured by FEF7s was affected by both smoking and work exposure, primarily rub ber worker exposure, (3) work, whether measured by duration or estimated cumulative exposure to VC and after ad|ustment for smoking effects, was not associated with reduced baseline pulmonary function lexcept tor rttrs). (4) although prevalence rates of impairment are not olien reported, the air flow im-" pairment (FtV/FVC, t-EFrs). rates appeared elevated only in the older smoker. ~ Respiratory symptoms and measurement of pulmonary function are two somewhat independent and yet overlapping methods tor investigating the risk of environmental exposures to the respira tory system Symptomatology suffers from the disadvantage of be- mg subjective, can show interobserver variation, and requires adequate recall on the part of the person being" interviewed: symptomatology is useful in diagnosis, particularly chronic bron- chitis!~T?idependent~validation of symptoms in practice turns out to be pulmonary fnnr-tinn numniw despite the fact that different, albeit overlapping, parameters are being measured. The observed association of reduced pulmonary function with increasing severity of symptoms increased the validity of respiratory symp tom information. The conclusion that VC exposure did not consti-t tute a significant respiratory hazard in this population was! Strengthened by similar results for both symptoms and pulmonary 1 function ' While one methodologic strength of this present study is the ability to make internal comparisons between work groups, it must be stressed that none of the groups can be regarded as hav ing worked in hazard-free conditions. Both rubber and plastics workers are exposed to varied levels of dust and fume, and it could be that reduction in lung function among chemicals workers (whether due to vinyl chloride exposure, or to some other agent) are being obscured because of similar reductions in the other job groups. The results ot FEF-vFVC impairment (pertaining to that part of the respiratory tract thought to be first affected by harmful exposure -- the small bronchioles) suggest increased abnormality Journal of Occupational Medicme/Vol 18, No 10/October 1976 rates in all workers. Indeed, for several of the pulmonary function tests the chemical workers had better results than rubber and plastics workers To assess the potential respiratory hazard of each exposure category, before-and-after shift tests were carried out on some workers. Any reduction in respiratory function over the shift suggests the likelihood of some harmful exposure in the working environment.'4 Srpokers overall had statistically significant reductions for all ventilatory tests; nonsmokers showed little reduction. The most obvious reductions were flow rates at low lung volumes, i.e.. mea sures of small airways performance. Chemical workers who were smokers had significant reductions for five of the seven tests, pre dominantly reflecting small airways obstructive change; both plastics and rubber workers who smoked showed reductions of similar magnitude. No clear picture emerges suggesting one |ob group faced greater daily respiratory insult than the others Re duction in small airways performance among nonsmokers in each job group suggests that all workers were exposed to agents with adverse respiratory effects. In a clean environment the average re sult for these nonsmokers would have been a slight increase in test performance. Whether these acute reversible changes have anv permanent effect is not known The significance of these findings is unclear. The small airways obstruction associated with work m the rubber division, i e . the control group, could be related to a number of environmental agents. The complexity of the industry and the heterogeneity of the control group does not allow for determining the etiologic agents. The rubber worker group was selected on the basis of lower particulate exposure and never hav ing worked in chemical or plastics. But they could have, and probably did, work in other jobs with higher exposures within the rubber division. A complete work history for each rubber worker would be required to investigate further the association of re duced small airways function with work in rubber. Fundamental and more difficult questions remain What is the biological significance of acute reversible reductions in small air ways function over a shift' What is the biological significance of statistically significant reductions in baseline pulmonary function over a longer time period? For FEFrs. the reduction is on the order of -1 %/year. Over a 40 year period, this would amount to a 40% decrease. However, some individuals have a reversible change of 40% in the course of a day. The association of working in rubber with a downward slope of the percent predicted FEF;s is a finding that requires further investigation of workers in other areas of the rubber plant, an investigation currently underway. The authors thank Mike Symons for advise on statistical matters. NIOSH mdustnaf hygienists f<x assistance in deriving the VC espnsure source Mary Jane Thomas for manuscript preparation, and union and company officials for their assistance in the project, References 1 Patty FA Industrial Hygiene and Toxicology. Vo! 2 John Wtlev and Sons. New York, 1963 2. Wilson RH, McCormick WE, Tatum CF. and Creech |L Occupational aeroosteolysis. report of 31 cases /A\fA 201 577-581 1967 3 Dmman BO el al, Occupational aeroosieolws I An nptdom'ofo^'cal Studv Ar(6 fnwron Hfth 22 61-73 1971 4 Cix)k WA et al Oct unalionaf acroosteolvsis If An industrial hv gienc study At^h Environ Ulth 22 74-Q2. 1971 5 Creech It and fohnson \1N Angiosarcoma of the liver m the manufac ture ot polwiml chlixide /OM 16 150-151. 1974 669 CUSAROSS 00137 6. Patty FA, Yant WP, and Waite CP Acute responses ot guinea pigs to vapors ot Some new commercial brganic compounds V vinvl chloride. US Pub Hllh Reports 45 1963-1971. 1930, 7. Torkelson TR, Oyen F. and Rowe VK: The toxicity of vinyl chloride as determined by repeated exposure of laboratory animals. Amer Indus Hyg Assoc I 22:354-361, 1961. 8. tester D. Greenberg TA, and Adams WR: Effects of single and repeated exposures of humans and rats to vinyl chloride Amer Indus Hyg Assoc I 24:265-275, 1963. 9. Boystov AN: Problems of industrial hygiene in new plants for the manufacture of synthetic resins and plastics. Ctgyena Truda 11:20-27, 1963. 10. Kuebler H: The physiological properties of aerosol propellants. Aerosol Age 9:44, 47-48. 50, 90-91. Abstract only. 1964 11. Vertkin Yl and Mamontov YR: Condition of the bronchopulmonary system in workers manufacturing articles of polyvinylchloride. Gig Tr Prof Zabol 14:29-32. 1970 12. Lange CE, Juhe S. Stein C. and Veltman G. Die Sogenante Vinylchlonde-Krankheit-ein berufsbedingte Svstems Klerose' /nr Arch Atbelts med 32:1-32, 1974. 13. Saende B, Lapis K, Nemes A, and Pinter A. Pneumoconiosis caused by the inhalation of polyvinylchloride dust. Med Lav 61 433-436. 1970 14. Miller A et al: Changes in pulmonary function in workers exposed to vinyl chloride and polyvinyl chloride. Ann NY Acad Set 246 42-52, 1975 15. Suggested Standardized Procedures for Closing Volume Determina tions (Nitrogen Method), distributed by Division of Lung Diseases, National Heart and Lung Institute, luly (1973) 16. Annual Report of the Chief Inspector of Factories for the Year 1951 London: HMSO Cond 8772, March, 1953 17. Smoking and Health Report of the Advisorv Committee to the Surgeon General of the PHS. USGPO, Washington. DC. 1964 and sub sequent reports, 18. Seltzer CC: Morphologic constitution and smoking IAMA 183 639645. 1963. 19. Higgins ITT: The epidemiology of chronic respiratory disease Prev Med 2:14-33, 1973. 20. Higgins ITT. et al Chronic respiratory disease in an industrial town1 A nine-year follow-up study (Preliminary report) Am I Pub Hllh 58 1667, 1968. 21 Ferns BG |r and Andersen DO, The prevalence of chrome respiratory disease in a New Hampshire town Am Rev Resp Dis 86 165-177, 1962 22 Higgins ITT, Ffiggins MW, Lockshin MD. and Canole N. Chronic respiratory disease in mining communities in Marion County. West Virginia Srit / Ind Med 25:165, 1968 23. Enterline PE and Lainhart WS: The relationship between coal mining and chronic nonspecific respiratory disease. Am / Publ Hlth 57.484, 1967, 24. Ferris BG |r et aT Chronic nonspecific respiratory disease in Berlin, New Hampshire, 1961 to 1967. ARRD 107:110-122, 1973. 25. Higgins ITT- Occupational Factors in Chronic Bronchitis and Em physema, in Bronchitis III Proc of 3rd Int. Conf on Bronchitis at Groningen. The Netherlands, 23-26 Sept 1960 26 Stebbms |H: Chronic respiratory disease among nonsmokers in Hagerstown, Maryland -- III Social class and chronic respiratory disease fnv Res 4 213-232, 1971 27. Stebbings )H Chronic respiratory disease among nonsmokers in Hagerstown, Maryland -- I Design of the study and prevalence of symp toms Env Res 4 146-162. 1971. 28. Denson PM et aT A survey of respiratory disease among New York City postal and transit workers I Prevalence of symptoms Env Res 1 265286, 1967. 29. Rossiter CE and Weill H. Synergism between dust exposure and Smoking: An artefact in the statistical analysis of lung function? Bull PhysioPath Resp 10 717, 1974 30 Morris IF, Koski A, and lohnson LC Spirometnc standards for hoalthv nonsmoking adults Amer Rev Resp Dis 103-57-67, 1971 31, Lapp NL and Hvatt RE Some factors affecting the relationship nr maximal expiratory flow to lung volume in health and disease D'S Chest 51 475, 1967 32 Bader ME et al Pulmonary function and radiographic change m 598 workers with varying duration of exposu'e to asbestos I Ml Sinai Hasp 37.492, 1970 33 Butst SA and Ross BB Predicted values for closing volumes using a modified single breath nitrogen test Amer Rev Resp Dis 107,744-752, 1973 34 Gamble IF. McMichael A|. Williams T. and Battigelli MC Respiratory function and symptoms An environmental-epidemiologic study of rubber workers exposed to a phenol-formaldehyde type resin, Amer Ind Hyg Assoc I 37 1976. Correction In "UV Keratoconjunctivitis Vs. Established Dose Effect Relationships," IOM, Aug 1976, p. 573, the term "Amp" was erroneously used with reference to emission characteristics of lamp. Wherever "Amp" appears, it was intended to read "Angstrom Units." 670 Occupational and Nonoccupational Factors on the Respiratory System of VC Workers/Gamble et al CUSAROSS 00138