Document v6goMy5333geMnnZ0Y7az9r6b

American Journal of Industrial Medicine 12:91-99 (1987) proportionate Mortality Ratio Analysis of Automobile Mechanics and Gasoline Service Station Workers in M@w Hampshire Eugene Schwartz, md, mph A proportionate mortality ratio (PMR) analysis of all deaths recorded from 1975 to 1985 among New Hampshire white male residents (age 20 years or older) was performed using death certificate information. Among automobile mechanics, the analysis revealed increases in mortality from leukemia (PMR = 178, N = 6); cancers of the oral cavity (PMR = 163, N = 4), lung (PMR = 112, N = 36), bladder (PMR = 169, N = 5), rectum (PMR = 182, N = 4), and lymphatic tissues (PMR = 200, N = 6); and cir rhosis of the liver (PMR = 140, N = 13) and suicide (PMR = 177, N = 22; p < 0.05). Workers in the gasoline service station industry experienced a leukemia mortality excess (PMR = 328, N = 3; p < 0.05) as well as increases in deaths from suicide (PMR = 162, N = 4), emphysema (PMR = 245, N = 4), and mental and psychoneurotic conditions (PMR = 394, N = 3). These workers are potentially ex posed to a variety of substances including gasoline vapor, benzene, solvents, lubricating oils and greases, and asbestos (from brake and clutch repair) as well as welding fumes and car and truck exhaust. Despite limitations regarding die small number of deaths and methodologic constraints, the results of this analysis suggest that one or more of the exposures experienced by these workers poses a significant carcinogenic risk. More definitive epidemiologic studies are required to determine if the leukemia excess is associated with exposure to benzene, gasoline, or other workplace substances. Key words: occupationally related leukemia mortality, benzene exposure, solvent exposure INTRODUCTION An estimated 1.5 million workers were employed in the automobile repair and gasoline service station industry during 1985 in the United States [Bureau of Labor Statistics, 1986]. Tradesmen in this industry provide a variety of services in gasoline stations as well as in brake, muffler, ignition, glass, body, and paint shops. Potential exposures include gasoline vapor, benzene, solvents, lubricating oils and greases, asbestos (from brake and clutch repair), fiberglass, epoxies, and adhesives as well as welding fumes and car and truck exhaust. As in many service-oriented industries, Bureau of Disease Control, Department of Public Health Services, New Hampshire Department of Health and Human Services, Concord. Address reprint requests to Dr. Eugene Schwartz, State Epidemiologist, New Hampshire Department of tb and Human Services, Division of Public Health Services, Bureau of Disease Control, 6 Hazen Unve- Concord, NH 03301. Accepted for publication March 12, 1987. W87 Alan R. Liss, Inc. HWBUI0007510 92 Schwartz epidemiologic investigations of these trades are particularly difficult to perfomr because workers are employed in small shops and generally are not unionized nof subject to any form of centralized personnel record-keeping requirements. j Among the diverse group of workers in this industry, automobile mechanics and gasoline station workers often labor together in small shops, have shared responsible' ities, and experience similar workplace exposures. Our knowledge of the mortality- experience of these workers stems from the incidental findings of population-based proportionate mortality ratio (PMR) studies and case reports. These studies have- revealed excesses of leukemia; cancers of the buccal cavity, esophagus, lung, bladder' testis, and kidney; nonmalignant respiratory disease; duodenal ulcers; multiple scle rosis; aplastic anemia; homicide; suicide; and injuries among automobile mechanics and gasoline service station workers, although these findings have by no means been consistent. Milham's [1983] study in Washington State revealed a mildly elevated PMR for leukemia among auto mechanics (PMR = 118, N = 34) as well as increases in the proportion of deaths from esophageal (PMR = 163, N = 22) and bladder cancer (PMR = 119, N = 28), nonmalignant respiratory disease (PMR = 123, N = 255), multiple sclerosis (PMR = 177, N = 14), and fires or explosions (PMR = 143, N = 20). Among gas station/garage owners and attendants, PMR elevations were found for cancers of the buccal cavity (PMR = 144, N = 8), kidney (PMR = 122, N = 15), bladder (PMR = 144, N = 26), and testis (PMR = 161, N = 7); duo denal ulcers (PMR = 194, N = 20); and aplastic anemia (PMR = 254, N = 4). Based on small numbers of deaths, Dubrow and Wegman [1984] found a mild ' PMR elevation for leukemia among auto mechanics and gas station attendants in ; Massachusetts (PMR = 123 and 127, respectively). Peterson and Milham [1980] 'i reported statistically significant PMR elevations for esophageal cancer (PMR = 232, ' N = 18), nonmalignant respiratory disease (PMR = 129, N = 118), and motor : vehicle injuries (PMR = 124, N = 97) as well as an increase in the proportion of deaths from homicide (PMR = 152, N = 16) among auto repairmen in California.' Significant elevations in lung cancer (PMR = 162, N = 24) and cirrhosis of the liver (PMR = 163, N = 32) as well as increases in cancers of the buccal cavity (PMR = 186, N = 6) and testis (PMR = 278, N = 4) and homicide (PMR = 179, N = 12) were observed among California auto service and gas station workers. Guralnick [ 1963] reported statistically significant elevations of lung cancer (PMR = 128, N = 119) and injury-related deaths (PMR = 107, N = 610) as well as increases in the proportion of deaths from buccal cavity cancer (PMR = 159, N = 27) and suicide (PMR = 113, N = 157) among auto mechanics in her national survey. The pattern of mortality among auto service and parking attendants was unremarkable tn that study. Finally, the Registrar General [1979] reported higher than expected lung cancer rates among motor mechanics and auto engineers in England and Wales. In addition, a higher than expected total mortality and a high cancer mortality rate were reported for garage proprietors. This paper reports the patterns of mortality among automobile mechanics and workers in the gasoline service station industry as determined by a state-wide, population-based analysis of death certificates in New Hampshire [Schwartz and Grady, 1986]. MATERIALS AND METHODS A PMR analysis was performed for all deaths occurring between 1975 and 1985 among white male residents (age 20 years or older) in New Hampshire (N = 37,426)- HWBUI0007511 difficult to perform j?gtr e not unionized nor '.rements, % obile mechanics and X shared responsibii- h ige of the mortality ? of population-based % These studies have % igus, lung, bladder, \ cers; multiple sole- omobile mechanics -i by no means been ; | elevated PMR for r I as increases in the ( 1 nd bladder cancer ; = 123, N = 255), ' ms (PMR = 143, R elevations were ley (PMR = 122, [ 61, N = 7); duo- I 254, N = 4). 1 a mild tiHHendants in d ITiIham [1980] :er (PMR = 232, 118), and motor the proportion of ten in California, rhosis of the liver te buccal cavity de (PMR = 179, station workers, of lung cancer f = 610) as well t (PMR = 159, ;s in her national attendants was tried higher than eers in England i a high cancer s the patterns of : service station eath certificates . 1975 and 1985 (N = 37,426). Occupation, industry, age, date, and cause of death information was abstracted from death certificates. The underlying cause of death was categorized according to the Eighth Revision of the International Classification of Diseases and coded by a trained nosologist at the New Hampshire Bureau of Vital and Health Statistics [U.S. DHEW, 1968]. Occupation and industry data were classified into one of 503 occupational and 231 industrial categories according to the Industry and Occupation Classification devised by the U.S. Bureau of the Census [1982], The analysis was performed by utilizing a computer program developed by Monson [1974], which calculates causespecific expected numbers of deaths based on the mortality experience of the U.S. general population. In this analysis, the proportion of deaths in specific cause of death categories is compared with the corresponding proportion of deaths in the U.S. population. The PMRs are standardized for the potentially confounding effects of age, sex, race, and year of death. In addition, standardized mortality odds ratios (SMORs) were derived by cal culating the ratio of mortality odds for selected causes of death using cancer deaths as controls. The SMOR is calculated in the same manner as the relative odds in casecontrol studies and provides a better estimate of the relative risk than the PMR [Miettinen and Wang, 1981], Statistically significant differences between observed and expected deaths and confidence intervals were determined by utilising a summary Mantel-Haenszel x2 test with 1 df. RESULTS Among the total population of decedents were 453 automobile mechanics (oc cupational code 505) and 134 who worked in the gasoline service station industry (industrial code 621). The distributions of observed and expected deaths are presented in Tables I and 13. Too few deaths were observed in the occupational category for gasoline and services station attendants to perform a meaningful analysis, so the industrial category for the gasoline service station industry was analyzed. Automobile mechanics revealed a statistically significant PMR elevation for suicide (PMR = 177, N = 22; p < 0.05). PMR increases for leukemia (PMR = 178, N = 6); cancers of the oral cavity (PMR = 163, N = 4), lung (PMR = 112, N = 36), bladder (PMR = 169, N = 5), rectum (PMR = 182, N = 4), and lymphatic tissues (PMR = 200, N = 6); and nonmalignant blood dyscrasias (PMR = 182, N = 2) and cirrhosis of the liver (PMR = 140, N = 13) were observed. Based on small numbers of deaths, workers in the gasoline service station industry revealed statistically significant PMR elevations for leukemia (PMR = 328, N = 3; p < 0.05) and mental and psychoneurotic and personality disorders (PMR = 394, N = 3; p < 0.05). PMR increases were also observed for emphy sema (PMR = 245, N = 4) and suicide (PMR = 162, N = 4). The SMORs are virtually identical to the PMRs, confirming the finding of excess leukemia among both groups. Table 133 reveals the distribution of leukemia and hematologic deaths delineated by occupation/industry, age, and type. Among the nine leukemia deaths observed, five were myeloid (including one erythroleukemia), two were lymphoid, and two were unspecified. In addition, two deaths from nonmalignant blood disorders among the mechanics included one aplastic anemia and one unspecified anemia. The latter death certificate also noted the diagnosis of "dysmyelopoiesis-preleukemia. ' Among ^.S HWBUI0007512 94 Schwartz TABLE I. Observed and Expected Deaths and PMRs for Automobile Mechanics (Occupational code SOS) in New Hampshire, 1975-1985 (Total deaths = 453) ICD* Cause of death 140-209 140-149 150-159 150 151 153 154 155-156 157 160-163 161 162-163 185 188 189 191-192 200-209 204-207 202,203,208,209 280-289 290-317 390-458 460-519 492 571 950-959 All malignant neoplasms Cancer of buccal cavity and phamyx Cancer of digestive organs Esophagus Stomach Large intestine Rectum Liver Pancreas Cancer of respiratory system Larynx Lung Cancer of prostate Cancer of bladder Cancer of kidney Cancer of brain and CNS All lymphopoietic cancer Leukemia and aleukemia Cancer of other lvmph tissue Diseases of blood Mental and psychoneurotic disorders Diseases of circulatory system Nonmalignant respiratory disease Emphysema Cirrhosis of liver Suicide All other causes of death Obsb Expc 101 95.8 4 2.5 24 24.2 3 2.1 4 3.5 5 9.1 4 2.2 2 1.8 4 4.8 37 33.7 1 1.2 36 32.2 8 8.5 5 2.9 1 2.2 2 2.6 12 9.2 6 3.4 6 3.0 2 1.1 1 3.2 215 218.4 27 31.5 4 5.2 13 9.3 22 12.4 72 81.3 PMRd 105 163 99 142 114 55 182 11! 84 no 84 m 95 169 45 78 131 178 200 182 32 98 86 77 140 177 89 95% Cl rLL UL ' 5/ 'O 89 125 62 429 0.99 67 146 0.00 46 437 0.38 43 301 0.06 23 129 1.90 69 475 1.47 28 440 0.02 32 222 o.i3 : 81 149 0.36 12 593 0.03 82 153 0.49 48 187 0.03 72 402 1.44 7 299 0.69 ' : 20 309 0.13 75 228 0.89 : 81 392 2.09 91 437 3.02 ; 47 713 0.75 \-l 5 200 1.49 * 90 108 0.11 v 60 123 0.70 j 29 203 0.28 ; 82 238 1.52 120 262 8.14' : 70 112 .06 "International Classification of Disease, 8th Revision. bObs, observed number of deaths. cExp, expected number of deaths. dPMR, (Obs/Exp) x 100. 'p < 0.05. the seven deaths from malignancies of other lymphatic tissues, four were classified as lymphomas, one as non-Hodgkin lymphoma, and two as multiple myeloma. Of the four deaths caused by mental or psychoneurotic and personality disorders, three were due to alcoholism and one was due to dementia. Among the 6 automobile mechanics who died of leukemia, occupational statements entered on death certificates included "automechanic" (two), "mechanic" (two), "auto repair" (one), and "mechanic-retired" (one). Similarly, the three leukemia deaths classified as gasoline service station workers included the occupational statements "service station attendant" (one), "manager-retired" (one), and "service station owner" (one). Because occupational histories were not available, analyses by job tide, duration of employment, and latency were not possible. ; ; : :v 7 DISCUSSION ;'4 State-wide, population-based PMR analyses serve to provide an indication of |, the status of workplace safety and health conditions and to generate hypotheses i 4 TABL1 (indust IC1_ 140-20 140-14 150-15 150 151 153 154 155-15 157 160-16 161 162-16 185 188 189 191-19 200-20 204-20 202,20: 280-28 290-31 390-45 460-5! 492 571 950-95 `Intern bObs, t "Exp, dPMR, 'p < 0 TABLl Indust Auto n Gasolii statioi `Acute bChror cErythi dAplas 'Chror fAcute `Chror Anem HWBUI0007513 Ue Mechanics (Occupational 95% Cl Expc PMRd TTUT 2 95.8 2.5 24.2 105 163 99 2.1 142 3.5 114 9.1 55 2.2 182 1.8 111 4.8 84 33.7 110 1.2 84 32.2 112 8.5 95 2.9 169 2.2 45 2.6 78 9.2 131 3.4 178 3.0 200 1.1 182 3-jjfl MP28 SI.?TM*86 5.2 77 9.3 140 2.4 177 1.3 89 89 125 0 36 62 429 0 99 67 146 0.0Q 46 437 0.38 43 301 0 ox 23 129 l.9o 69 475 1.47 28 440 0.02 32 222 0.13 81 149 0.36 12 593 0.03 82 153 0.49 48 187 0.03 72 402 1.44 7 299 0.69 20 309 0.13 75 228 0.89 81 392 2.09 91 437 3.02 47 713 0.75 5 200 1.49 90 108 0.11 60 123 0.70 29 203 0.28 82 238 1.52 120 262 8.14' 70 112 .06 ' ' - [ 1 four were classified as iltiple myeloma. Of the ity disorders, three were mia, occupational stateic" (two), "mechanic" milady, the three leuke:luded the occupational rf" (one), and "service t available, analyses by >le. TABLE D Observed and Expected Deaths and PMRs for Gasoline Service Station Industry (Industrial code 621) in New Hampshire, 1975-1985 (Total deaths = 134) ,rn` 95% Cl --------------------- ggHse_of death___ _________ Obsb Expc PMRd LL UL y2 140-209 140-149 150-159 150 151 153 154 155-156 157 160-163 161 162-163 185 188 189 191-192 200-209 204-207 202,203,208,209 280-289 290-317 390-458 460-519 492 571 950-959 All malignant neoplasms Cancer of buccal cavity and pharynx Cancer of digestive organs Esophagus Stomach Large intestine Rectum Liver Pancreas Cancer of respiratory system Larynx Lung Cancer of prostate Cancer of bladder Cancer of kidney Cancer of brain and CNS All lymphopoietic cancer Leukemia and aleukemia Cancer of other lymph tissue Diseases of blood Mental and psychoneurotic disorders Diseases of circulatory system Nonmalignant respiratory disease emphysema Cirrhosis of liver Suicide All other causes of death 27 28.0 0 0.7 9 7.2 2 0.6 1 1.0 3 2.7 1 0.7 0 0.5 1 1.4 7 10.1 0 0.4 7 9.7 3 2.5 1 0.9 1 0.7 0 0.7 4 2.5 3 0.9 1 0.9 0 0.3 3 0.8 68 63.3 12 9.2 4 1.6 3 2.6 4 2.5 17 27.3 96 0 126 322 96 111 152 0 70 69 0 73 119 112 152 0 159 328 116 0 394 108 131 245 115 162 62 69 134 0.05 0 00 67 236 0.50 87 1188 3.07 14 675 0.00 36 340 0.03 22 1061 0.18 0 00 10 488 0.13 34 140 1.04 0 00 36 147 0.80 39 364 0.10 16 790 0.01 22 1057 0.18 0 00 61 416 0.89 113 951 4.80' 16 813 0.02 0 00 139 1118 6.62' 91 126 0.76 76 225 0.97 96 628 3.50 38 350 0.06 64 414 1.02 39 100 3.89 'International Classification of Disease, 8th Revision. bObs, observed number of deaths. `Exp, expected number of deaths. dPMR, (Obs/Exp) x 100. ep < 0.05. TABLE in. Distribution of Leukemia and Hematologic Deaths Delineated by Occupation/ Occupation/Industry Auto mechanics Gasoline service station industry Age group (years) Code 20-29 30-39 40-49 50-59 60-69 70-79 80-89 90-99 Total 505 1* 621 jb r 2b,d 2'-f 2*-h 8 ,, 1' 3 'Acute myelogenous leukemia. bChronic myelogenous leukemia. 'Erythroleukcmia. dAplastic anemia. HWBUI0007514 96 Schwartz regarding previously undetected potential associations between workplace exposures ^ and patterns of mortality. This analysis provided the opportunity to examine the^ patterns of mortality of more than 200 industrial and 500 occupational groups. The pattems of mortality for automobile mechanics and workers in the gasoline service ' v:-. station industry are presented because of the paucity of epidemiologic information 'S regarding work in these trades. |L The patterns of mortality of automobile mechanics and workers in the gasoline service station industry suggest that these tradesmen experience an increased leukemia ^ risk. The PMR for leukemia among the combined group of observed deaths (N = 9) '$ is 211 (95% Cl 116, 400; p < 0.05). This finding is consistent with reports noting *1 an increased risk of leukemia among men occupationally exposed to petroleum products relating to gas station and auto mechanic jobs [Milham, 1983; Dubrow and K Wegman, 1984; Brandt et al, 1978], Because work history and exposure data are ^ unavailable, no conclusion can be drawn regarding a particular etiologic agent. # However, among the potentially responsible chemical agents known to be present in service stations and garages, most suspect would be gasoline and other solvents M containing benzene. The leukemogenic potential of benzene is well known and has * been demonstrated among workers in a variety of trades including the shoe, rubber, f? petrochemical, and refining industries [Aksoy, 1980; Infante et al, 1977; McMichael |f et al, 1975; Thomas et al, 1980; Vigliani, 1976]. f In addition to leukemia, benzene exposure is known to increase the risk of nonmalignant blood disorders including anemia, pancytopenia, and aplastic anemia, j The findings of one death from aplastic anemia and another from "anemia-preieuke- ^ mia" are consistent with previous case reports of these diseases related to benzene y. exposure [Vigliani, 1976]. Case reports of similar nonmalignant blood disorders x among workers using gasoline as a solvent have been reported by Verwilghen et al f [1975], - Further, the finding of an excess proportion of deaths from suicide in both ' itgroups is consistent with the known neurotoxic potential of solvent exposure. Acute exposure to solvents may produce transient and reversible central nervous system symptoms including headache, dizziness, and incoordination. At higher concentra tions, convulsions, loss of consciousness, and death may result. Long-term exposure to solvents can result in memory impairment and behavioral changes, including irritability, depressive symptoms, and emotional instability. Chronic, irreversible brain damage may result following prolonged exposure to high concentrations, as reported among solvent sniffers. In view of the likelihood that work in service stations involves chronic exposure, it is not surprising that auto mechanics and service station workers experience a greater proportion of deaths from suicide. This finding is supported by Guralnick's study [1963], which reported an increased suicide risk among auto mechanics, and other studies which have reported an increased risk of suicide among solvent-exposed workers, including chemists, chemical workers, and rubber workers [Li et al, 1969; Bond et al, 1986; Andjelkovich et al, 1977]. It is possible that the neurotoxic effects of workplace solvent exposure were potentiated by ethanol use [Hills and Venable, 1982]. The likelihood of ethanol use among automobile mechanics and service station workers is evidenced by the observation of deaths from cirrhosis of the liver, cancers of the buccal cavity, and alcoholism. Gasoline is a complex mixture of hydrocarbons blended with a combination of additives, including antiknock agents, inhibitors, and dyes. Of the more than 40 HWBUI0007515 an workplace exposures ' trtunity to examine the 7 .cupational groups. The ' in the gasoline service demiologic information : workers in the gasoline e an increased leukemia >served deaths (N = 9) ent with reports noting exposed to petroleum am, 1983; Dubrow and and exposure data are icular etiologic agent, known to be present in ine and other solvents is well known and has iding the shoe, rubber, ;t al, 1977; McMichael . > ` ; , 0 jflfe|ase ^ t, ^Hfplastic anemia, om '"anemia-preleukeses related to benzene gnant blood disorders .d by Verwilghen et al from suicide in both >lvent exposure. Acute entral nervous system At higher concentrat. Long-term exposure al changes, including Chronic, irreversible igh concentrations, as /ork in service stations ics and service station cide. This finding is ncreased suicide risk 1 an increased risk of hemical workers, and ich et al, 1977]. It is sure were potentiated f ethanol use among by the observation of tnd alcoholism, vith a_ combination of DfJHhpore than 40 s Ji . I. moonents, most are paraffins, naphthenes, aromatics, and olefins. The benzene content of gasoline is between 1% and 3% by volume and is higher in unleaded than in leaded fuels [McDermott and Voss, 1979]. Industrial hygiene studies of service station employees have found the time-weighted average (TWA) exposure to benzene among service station workers to range from below 1 ppm to 2.08 ppm (mean range 0 02-0-24 ppm) [McDermott and Vos, 1979]. The TWA exposure to total gasoline vapor ranged from below 1 ppm to 114 ppm. Exposure levels were influenced by the workload, weather conditions, work practices, and presence of a vapor recovery system. In addition to inhalation, these workers likely risked exposure through skin absorption if hands were immersed in gasoline or other solvents during the process of auto repair and related degreasing operations or if gasoline was used as a solvent to aid in hand washing. Recent animal studies reveal that approximately 1 % of benzene applied to skin may be absorbed percutaneously [Susten et al, 1985]. Further, it is possible that gasoline was ingested if workers siphoned gasoline by mouth. Recent data indicate that gasoline vapor may be carcinogenic apart from its benzene component. An inhalation study of rats and mice produced renal carcinomas and sarcomas with some evidence of a dose-response relationship [MacFarland et al, 1984]. Further, a review of the epidemiologic literature by Enterline and Viren [1985] revealed some evidence supporting the association between gasoline exposure and kidney cancer in humans. An excess of kidney cancer was not observed in the present analysis. Although there is a good correlation between substances that cause cancer in experimental animals and their ability to cause cancer in humans, there is not, however, always a good correlation between the specific sites of cancer observed in experimental animals and in humans. The finding of a lung cancer excess among automobile mechanics is consistent with their potential exposure to asbestos arising from brake and clutch repair. Based on small numbers of deaths, an excess of gastrointestinal cancer was observed; however, the PMR for nonmalignant respiratory diseases was not elevated. Service station workers experienced an elevated PMR for emphysema; however, lung cancer mortality was not increased. Because asbestosis is often misdiagnosed as chronic obstructive lung disease, the observed excess of emphysema mortality among these workers may in fact reflect an increase in asbestos-related lung disease. Additional clinical data would be needed to determine the exact pathology of the observed cases. STUDY LIMITATIONS PMR analyses are known to have some limitations. In particular, because the all-cause mortality must equal 100%, an over- or under-representation of one cause may influence the PMR of other causes of death (the so-called "see-saw" effect). However, no deficit in cardiovascular disease (the major cause of mortality in the United States) was present in our data, which might otherwise have tended to spuriously inflate the PMR for cancer. Further, the SMOR analysis, which focuses on an odds ratio rather than cause-specific proportions, produced results virtually identical to the PMR analysis. This analysis adds confidence that the observed increased leukemia risk is not the result of the "see-saw" effect. Other limitations could stem from use of the national mortality rates to derive the expected number of deaths and the inability to control for potentially confounding factors, such as cigarette HWBUI0007516 98 Schwartz smoking and social class. Although the New Hampshire population is known to have experienced an excess total cancer mortality rate compared to the national rate a mortality excess has not been exhibited for leukemia [Riggan et al, 1983], Further more, epidemiologic studies have not implicated cigarette smoking or socioeconomic status as major risk factors for leukemia [Linet, 1985]. The potential limitations stemming from the use of death certificate data are well known. It is possible that nonrandom misclassification of cause of death or occupational/industrial information influenced the results by either raising or lowering the leukemia risk observed. In addition, the analysis of the industrial rather than the occupational category for gasoline service station workers may have biased the overall exposure of the group. For example, managers and owners may have had minimal workplace exposure. Alternatively, these individuals may have experienced consid erable exposure, especially if they assisted in maintenance or repair operations or worked in the trade early in their careers as entry-level employees. If the former is true, the study findings suggest that the risk of leukemia associated with low-level benzene exposure may be greater than previously believed. If the latter is true, then it is possible that the overall level of exposure among individuals in this industry may be higher than previously reported. Further, because many causes of death were examined and many comparisons made, some of the study findings may be due to chance. CONCLUSION This analysis suggests that one or more of the exposures experienced by automobile mechanics and service station workers poses a carcinogenic risk. Al though numerous agents are suspect, the finding of a leukemia excess among auto mobile mechanics and workers in the gasoline service station industry is consistent with exposure to benzene, a known component of gasoline. In view of the large occupational and nonoccupational population at risk of exposure, these findings serve to support the need for more definitive studies. In the interim, prudent public health practice requires the need to inform auto mechanics, gas station employees, and other individuals who pump gasoline of the potential cancer hazard. Recommendations should include discontinuing the use of gasoline as a solvent for removing grease from auto parts and for hand cleansing and cautioning against siphoning gasoline by mouth. Further, the use of vapor recovery systems could help to reduce occupational and general environmental exposure to gasoline and benzene vapors during the refueling process, thus reducing the cancer risk. REFERENCES Andjelkovich D, Taulbee J, Symons M, Williams T (1977): Mortality of rubber workers with reference to work experience. J Occupational Med 19:397-405. Aksoy M (1980): Different types of malignancies due to occupational exposure to benzene: Review of recent observations in Turkey. Environ Res 23:181-190. Bond GG, McLaren EA, Baldwin CL, Cook RR (1986): An update of mortality among chemical workers exposed to benzene. Br J Indust Med 43:685-691. Brandt L. Nilsson PG, Mitelman F (1978): Occupational exposure to petroleum products in men with acute non-lymphocytic leukaemia. Br Med J i.553. Bureau of Labor Statistics (1986): "Employment and Earnings." Washington, DC: U.S. Dept, of Labor, 33:187. DiiW' HWBUI0007517 is known to have e national rate, a 1, 1983], Furtheror socioeconomic 1 - :rtificate data are ause of death or using or lowering al rather than the biased the overall ave had minimal >erienced considair operations or If the former is d with low-level itter is true, then ihis industry may s of death were s may be due to #need by Dgerar risk. Alsss among autotry is consistent ew of the large ;e findings serve ;nt public health jyees, and other commendations amoving grease ting gasoline by ce occupational ors during the :ers with reference rnzene: Review of chemical workers ducts in men with S. Dept, of Labor, pubrow R, Wegman DH (1984): "Occupational Characteristics of Cancer Victims in Massachusetts 1971-1973." Cincinnati; U.S. Dept, of Health and Human Services, Centers for Disease Control, NIOSH Pub!. No. 84-109. Enterline PE, Viren J (1985): Epidemiologic evidence for an association between gasoline and kidney cancer. Environ Health Perspect 62:303-312. Guralnick L (1963): "Mortality by Occupation and Cause of Death Among Men 20 to 64 Years of Age. United States, 1950." Washington, DC: U.S. Dept, of Health Education and Welfare; Public Health Service Special Report 53. Hills BW, Venable, HL (1982): The interaction of ethyl alcohol and industrial chemicals. Am J Indust Med 3:321-325. Infante PF, Rinsky RA, Wagoner JK, Young RL (1977): Leukemia in benzene workers. Lancet 2:7678. Li FP, Fraumeni JF, Mantel N, Miller RW (1969): Cancer mortality among chemists. J Natl Cancer Inst 43:1159-1164. Linet MS (1985): "The Leukemias, Epidemiologic Aspects." New York: Oxford University Press. MacFarland HN, Ulrich CE, Holdsworth CD, Kitchen DN, Halliwell WH, Blum SC (1984): A chronic inhalation study with unleaded gasoline vapor. J Am Coll Toxicol 3:231-247. McDermott HJ, Vos GA (1979): Service station attendants' exposure to benzene and gasoline vapors. Am Indust Hygiene Assoc J 40:315-321. McMichael AJ, Spinas R, Kupper LL, Gamble JF (1975): Solvent exposure and leukemia among rubber workers: An epidemiologic study. J Occupational Med 17:234-239. Miettinen OS, Wang J (1981): An alternative to the proportionate mortality ratio. Am J Epidemiol 114:144-148. Milham S (1983): "Occupational Mortality in Washington State, 1950-1979." Cincinnati; U.S. Dept, of Health and Human Services, Centers for Disease Control, NIOSH Publ. No. 83-116. Monson RR (1974): Analysis of relative survival and proportional mortality. Computers Biomed Res 7:325-332. Peterson GR, Milham S (1980): "Occupational Mortality in the State of California 1959-1961." Cincinnati; U.S. Dept, of Health and Human Services, Centers for Disease Control, NIOSH Publ. No. 80-104. Registrar General (1979): "Decennial Supplement for England and Wales, 1970-1972: Occupational Mortality." London: Office of Population Censuses and Surveys, Her Majesty's Stationery Office. Riggan WB, Acquavella JF, Mason TJ (1983): "U.S. Cancer Mortality Rates and Trends, 1950-1979." Washington, DC: NCI/USEPA, EPA-600/l-83-015a. Schwartz E, Grady K (1986): "Patterns of Occupational Mortality in New Hampshire 1975-1985." Concord, NH: N.H. Division of Public Health Services. Susten AS, Dames BL, Burg JR, Niemeier RW (1985): Percutaneous penetration of benzene in hairless mice: An estimate of dermal absorption during tire-building operations. Am J Indust Med 7:323335. Thomas TL, Decoufle P, Moure-Eraso R (1980): Mortality among workers employed in petroleum refining and petrochemical plants. J Occupational Med 22:97-103. U.S. Bureau of the Census (1982): "1980 Census of the Population--Classified Index of Industries and Occupations." Washington, DC: U.S. Dept, of Commerce. U.S.D.H.E.W. (1968): "International Classification of Diseases, 8th Revision." Washington, DC: U.S. Public Health Service. Verwilghen RL, Van Dorpe A, Veulemans H (1975): Dangers of petrol used as a solvent. Lancet ii. 1156. Vigliani EC (1976): Leukemia associated with benzene exposure. Ann NY Acad Sci 271:143-151. 'V HWBUI0007518