Document EdnX4rkDwzQ0pvB5766vZJXy4

664 Bririlh Journal of Industrial Medicine ]992;49;ti64-670 Mortality among firefighters from three northwestern United States cities Paul A Demers, Nicholas J Heyer, Linda Rosenstock Abstract To explore whether exposure among fire fighters to fire smoke could lead to anincreased risk of cancer, lung disease, and heart disease, the mortality of 4546 firefighter* who were employed by the cities of Seattle and Tacoma, WA and Portland, OR for at least one year between 1944 and 1979 were compared with United States national mortalities and with mortalityofpoUceofficersfromtbesamecides. Between 1945 and 1989,1169 deaths occurred in the studypopulationand 1162 deathcertificates (99%) were collected. Mortality due to all causes, ischaemic heart disease, and most other non-mallgnant diseases was less than expected based upon United States rates for white men. There was no excess risk at overall mortality from cancer but excesses of brain tumours (standardised mortality ratio (SMB) = 2-09, 95% confidence interval (95% Cl) 1-3-3-2) and lymphatic and haemstopoetic cancers (SMR -- T31, 95% Cl * 0-9-1-8) were found. Younger firefighters ( <40 years ofage) appeared to have an excess risk of cancer (SMR - 1-45, 95% Cl 0-8-2-39), primarily due to brain cancer (SMR - 3-75, 95% a 1-2-8-7). The fid of lymphatic and haematopoetic cancers was greatest for men with at least 30 years of exposed employment (SMR 2-05, 95% Cl 1-1-3-6), especially for leukaemia (SMR - 2-60,95% Cl 1-0-5-4). Since the end of the second world war the use of synthetic materials for both the structures and interiors of buildings has increased the complexity and toxicity of the smoke generated when these buildings catch fire.1* The potential exposure to suspected or known carcinogens has raised the Department ofEnvironmental Health PADoners, NJ Heyer, L Roieunock Department of Epidemiology PADemerj Department of Medicine, University ofWashington, Seattle, Washington, USA L Rcuenttock concern that firefighters may be at excess risk of cancer. Benzene and polycyclic aromatic hydro carbons are likely encountered atmost fires and other, less common, exposures may include asbestos, aromatic amines, chlorinated dioxins, and other potential carcinogens." Excesses of brain cancer, cancers ofthe colon or rectum, malignant melanoma or skin cancer, bladder cancer, leukaemia, and multiple myeloma have been found,*-1' although the reaults have been far from consistent. Perhaps surprisingly, given a priori suspicions, only one cohort study hat noted an excess of lung cancer in firefighters."1 Itisplausiblethatfirefighters could also beat excess risk of death due to heart and respiratory disease. Many respiratory irritants, such as hydrogen chloride, nitrogen dioxides, isocyanates, and acrolein, are commonly present in smoke."* Evidence exists for respiratory dysfunction after acute high exposures1*'1* although studies designed to look at chronic effects have produced mixed results."1* An increased risk of cardiovascular disease due to intense physical and psychological stress after periods ofinactivity orexposure to carbon monoxide and other trade gases is also plausible,1"* Most cohort mortality studies, however, have found firefighters to be at the same or lower risk than the general population for both heart and lung disease. Death rotes for the general population have been used as the reference in most mortality studies of occupational cohorts. A major bias introduced by using general population rates has been terihed the healthy worker effect.*"* In many ways firefighters, with their strict physical entry requirements and good employment benefits, typify a population-;in which a particularly strong healthy worker effect would be expected. This may in part account for the low risk of death due to heart and respiratory disease noted in these studies; however, when police, an occupation with similar entrance criteria, have been used as a reference population1*" evidence that firefightera ore at increased risk of respiratory disease has been found. Also, apreviously reported study ofa sub-population of this same cohort found that the risk of heart disease increased with duration of employment." * Mortalii In 14 Seattlel racpoeu expand in the i tamed the res follow | Mcthc The st cmploj 1944 a: Wasbi cxclud employ nurabe of activ used ai Record were a was as; prevail lacked fircsmjf firefigra samedf group. The 31 Dei collect! $ twin * inform k record! -f^ Oregoi motor < t'. Index-i 1 contid! T last ki X subseq i death 1 \ Index.! former tion it * formed , thedes Stan i Tahiti Status Quran)* Retired 1 Other DttcMCd} uSnSJf Tool 1 Yantof<| *Percmttf Material may be protected by copyright law (Title 17, U.S. Code) 392;49;664-670 Mortality amongfirefightersfrom three northwestern United Staler cities 665 restern q In 1984 we began a retrospective cohort study of with United States white men were calculated using Seattle firefighters to explore the relstion between the microcomputer version of the Occupational exposure to fire smoke and mortality." Later we Mortality Analysis Program.11 Reference rates for expanded the study to include two other major cities United Stares white men were obtained from the , in the region and to collect data on police from the National Institute for Occupational Safety and ; same cities as a comparison group. This is a report of Health. White male rates were used because most the results of the expanded mortality study with firefighters from the citiesstudied wereCaucasianand ! follow up to the end of 1989. . department records did not include information on race. Confidence intervals were calculated using a ? Methods Poisson distribution. Incidence density ratios The study population consists of all men who were (IDRs) and 95% confidence intervals (95% CIs) for employed as firefighters for at least one year between firefighters relative to police were calculated using ;xcess rink of j 1944 and 1979 by the cities of Seattle and Tacoma, Mantel-Haenszel methods with standardisation by made hydro- i Washington and Portland, Oregon. Women were five year age groups and time periods and test based ires and other, j excluded from the study because they first began confidence intervals.11 Mortality was examined in ude asbestos, employment a* firefighters in the 1970s and their stratified analyses by years of fire combat exposure, t9, and other number* continue to be comparatively small. Yean years since first employmentas afirefighter, and ggeat brain cancer, , of active duty in positions involving fire combat was risk. . ant melanoma used as a surrogate measure of exposure to smoke. ukaemia, and Records ofthe Seattle and Portland fire departments 5 although the were reviewed and no time for exposure to fire smoke Results tent. Perhaps was assigned for years spent in administration, fire Complete follow up was achieved for 98% of the >ns, only one ' prevention, or support services. Because Tacoma 4401 firefighters (table 1). Between 1945 and 1989, lung cancer in lacked the necessary records to make this distinction, 1169 deaths occurred and 1162 death certificates fire smoke exposure time was assigned for all yean of (99%) were collected. The comparison cohort .Iso beatexcess firefighter employment. A cohort of police from the consisted of 3676 police officers and complete follow ratory disease, ' same cities was also identified for use as a comparison up information was attained for 3599 (98%). During a* hydrogen group. the follow up period 714 police deaths were identified yanates, and The follow up period was from 1 January 1945 to and 703 death certificates (98%) were collected. in smoke.1-1* 31 December 1989. Follow up for vital status and The risk ofdeath due to any cause among firefight function after ` collection of death certificates were performed for ers was less than expected (SMR -- 0 81, 95% Cl udies designed both the firefighter and police cohorts using 0-77-0*86) due to a lower than expected risk of most oduced mixed information from pension board and department types ofnon-malignant diseases (table 2). A twofold cardiovascular records, the death records of Washington and excess of brain tumours was seen (SMR 2-09, psychological , Oregon, the records of the Washington and Oregon 95% Cl 131-3*17). The death certificates listed osure to carbon j motor vehicle departments, and the National Death seven of the tumours as glioblastoma multiforme, o plausible.3*"" i Index. Those who were lost to follow up were only three as astrocytoma, three as other gliomas, five as 'er, have found ! considered at risk until the date on which they were other or unspecified malignant brain tumours, and t risk than the t last known to be alive. Persons lost to follow up four as unspecified brain tumours. Smaller excesses , lung diseate. : subsequent to 1978 were assumed to be alive if no were found for cancers of the lymphatic and haema don have been ! death was identified through the National Death topoietic tissue* (SMR = 1 31, 95% Cl 0*92-1*81) dity studies of ! Index. Underlying cause of death was coded by a and prostate (SMR 1-34,95% Cl 0*90-1*91), The introduced by ' former Washington state nosologist after informa- number of observed cases of most ocher cancers, ten termed the 4 tion identifying the deceased person as either a including lung cancer, was similar to expected with ays firefighters, former firefighter or police officer was removed from only cancers of the bladder (SMR = 0*23, 95% Cl uirement* and the death certificate. 0 03-0*83) and kidney (SMR - 0*27, 93%. Cl . population in Standardised mortality ratios (SMRs) compared 0*03-0*97) significantly tower than expected. 'fThe ' worker effect account for the Tablet F-ntployment vitalstatus andyean offollow up at J January 1990 * piratory disease hen police, an erla, have been evidence that piratory disease lortedstudyofa found that the th duration of Stents Cornutly employed Retired Other alive Deceased Certificate* collected Unknown itatoi Total Yean of follow uj> ' Steak 610 782 318 516 510 55 2281 64388 Portland a 396 95 509 508 24 1462 41085 Tacoma in 239 22 144 144 16 63* 17379 Total 1285 1417 435 1169 1162 95 4401 122852 cm; <(3*5j <10$ (37) (99)* ( *Per cent ofdcsth certificates collected m Material may be protected by copyright law (Title 17, U.S. Code) 665 Table 2 Seattle, Portland, and Tacoma firtfighter mortality: 1945-49 Cmt* of death (ICD 9 codes) AJI cause* (001-499) All canon (140-152'2 156-9-165-9, 170-175,179-208) Orid Mtd phiryngral ctnctrt (140-149) Cheophgcal cancer (150) Stomach cancer {151) Colon cancct (152,155) .. Recnlcmccf (154) ' Biliary and liver cnDcer()55 0-155*1.156) PaocTcaik: esactr (157) laryngeal caaotr (161) Lung caaccr(162) Prottara cancer (185) Kidney cancer (189-0-189 2) Bladder and other urinary cancer* (188,189 3-1899) Skm cancer (172, 173) Brain and nervoui system tumours (391,192,237*><*237*9I239-6*239'7) Brain and nervous system cancers (191,192) Unspecified nervous system tumours (237*5-237*9,239-6-239-7) LymphaHc/haentotoporetie cenoers (300-208) Lymphosarcoma and reficubswcomi (200) Hodgkin's disease (201) LeunemJa (204-208) Other lymphatichaematopoietic (202,203) Hears disease (390-398,402,404,410-*J 4,420-429) Ischaemic bean disease (410-414) Other diculatory disease (401,403,405,415-417,430-438,440-459) Cerebrovascular disease (430-438) Dieros of arteries, veins and pulmonary circulation (415-417,440-459) Respiratory disease (460-466,470-478, 480-487, 490-519) Acute upper respiratory infection (460-466) Pneumonia (48CM86) Chronic respiratory diseases (470*478,490-519) Emphysema (492) Asthma (493) COPD and other respiratory disease (470-478,494-519) COPD ** Qironic obstructive pulmonary disease. Doners, Heyer, Rosemtark Dtatks 1169 291 7 6 16 24 8 6 14 2 55 30 2 .2 6 22 18 4 37 7 3 15 12 46) 394 131 79 48 81 2 22 56 20 3 32 SMJt 0-8) 0-95 0 81 083 1-07 0*85 0-93 119 0-99 0-47 0-96 134 0-27 O'23 O'98 209 207 2-20 1*31 1-42 1-05 1*27 1-40 0*79 0*82 0-96 0-85 124 0*89 3*57 0*67 100 1 19 1-05 0-98 rjx> (0 77-OB6) (0-8S-1-07) (0-33-1-66) (0-30-1 SO) (0-61-173) (0-54-1-26) (0-41-1-87) (0-44-2-W) (0-44-1-49) (006-1-70) (0,77**M7'i (0-90-1-91) (0-03-0-97) (0-03-0-83) (0-36-2-13) 0 31-3*17) (123-3*28) (0-60-5 62) ' (0*92-1*81) (0 57-2-93) (0*22-3-08) (071-2-09) (0-72-2-44) (0-72-0-87) (0-74-0-90) (0-80-114) (0-67-1-06) (0*91-1-64) (0-71-1 -10) (0 43-12-9) (O-42-i -on (0*76-1 30) (0-72-1 -S3) (0-22-3-08) (0-67-1-38) risks for death due to heart and circulatory disease were similar to or lower than expected with the exception of diseases of the arteries, veins, and pulmonary circulation, which were somewhat increased (SMR -- 1 -24,95% Cl 091-1'64). Table 3 presents firefighter mortality relative to that of police and police mortality relative to that of United States white men fot causes of death of a priori interest and those found to be in excess as shown in table 2. Hodgkin's disease, asthma, and acute respiratory infections were not included in the table because no deaths due to these causes were found among police. Although the confidence limits were wide, firefighters appear to have a higher risk than police of colon cancer, prostate cancer, brain tumours, "other" lymphatic and haematopoietic cancers, and emphysema. The category of "other" lymphatic and haematopoietic cancer include! multiple myeloma (seven out of 12 firefighter and two out of five police deaths were in this category). Although national rates for the study period were not available,the risk ofmultiple myelomafor firefighters relative to police was 1-91 (95% Cl 0-4-8-4). Of the brain tumours among police, five were listed on the death certificates as glioblastoma multiforme, two as astrocytomas, and one as a malignant neuroblastoma. Firefighters were at somewhat lower risk than police for deaths due to all causes and circulatory disease and at much lower risk of bladder cancer. The causes ofdeath that were found to be in excess were further analysed by duration of exposed employment (table 4). The risks for lymphatic and haematopoietic cancer, especially leukaemia, and diseases ofthe arteries, veins, and pulmonary circula tion were highest for firefighters with at least 30 years of exposure, although the risks do not increase consistently with duration of exposed employment. The risk of leukaemia in firefighters with 30 years of exposed employment remained increased (IDR - 1-80, 95% Cl O-6-5-4) when comparisons were made with police, whereas the risk of all lymphatic and haematopoietic cancers did not (IDR - 1-14, 95% Cl 0-5-2-6). The risk of mortality from all chronic respiratory disease peaked amongfirefighters with 20 to 29 years ofexposure; the excess risk of emphysema was highest among those with 10 to 19 years of exposure. Lagging exposures by 10 years to allow for a latent period13 increased the risk for 30 or more years of exposure for all lymphatic and haematopoietic neo plasms (SMR - 2-73, 95% Cl 1-36-4-88), leukaemia (SMR 3-63, 95% Cl 1-46-7-48), diseases Mormtiu Table 3 ] States c of the; (SMR i (smr; further^ fireflghj (SMR [ Fired employ! (SmrT maiigni (SMRT puimotl emphyf ers alsd (IDR : (IDR 4 (IDR police, 1 In g* washig TriU 4 Seat itu of bath aid of the if Ptaunary rircuf retDirtcl npkyiems " Material may be protected by copyright law (Title 17, U.S. Code) teyer, Rostnstack (95%) (0-77-0-SO) CO-83-1-07) (033-1-66) (030-1-80) (061-1 73) (054-1-26) (04J-1-87) (0-44-2-39) (0 49-1-49) (0-06-1-70) (0-77-1-17) (090-1-91) (003-0-97) (0-03-0-83) (0-36-2-13) (1-31-3-17) (1-23-3-28) (0-60-3-62) (0-92-1-81) (037-293) (0-22-308) (0-71-209) (0-72-2-44) (0-72-0-87) (074-0-90) (0-80-1-14) (067-1-06) (091-1-64) (071-1-10) (043-12-9) (0 42-101) (0 76-1 30) (o-72-1 83) (022-3-08) (067-1 38) risk than police ulatory disease icer. 3 to be in excess in of exposed lymphatic and eukaemia, and -nonary drculaatleast 30 years o not increase d employment, hters with 30 lined increased Ml comparisons the risk of all ncers did not The risk of disease peaked ofexposure) the at among those How for a latent : more years of mtopoietic neo;l 1-36-4-88), -7-48), diseases i Mortality amongfirtfightersfrom three northwestern United Suites cilia 667 Table 3 Seattle, Portland, and Tacomafirefighter mortality comparedwith police andpolice mortality compared aith United States white male ratet; 1945-89 Cmutof death Firtfightm vpotto Dtolhs IDR Ail (suites All cancers Colon cancer Rectal cancer * " ' Biliary passages and tfver cancer Trachea, bronchus, and lung cancer Prostate cancer Bladder cancer Skin cancer Bnin uid nemwn tynem nunoun Brain and nervous system cancat Lymptatk/haemacopoletlc cancers Lymphosarcoma and fetlculosttCOtti* l^ukaemk Other lyjnphadc/heonatopoietic Heart diseases Ischaemic heart disease Other ditnlaiory disease Ceichrovainilar disease Diseases of the arteries, veins met pulmonary circulation Respiratory disease Pneumonia Chronic respiratory diseases Emphysema COPD and miscellaneous lung rthrasc m 24 6 6 95 30 2 6 22 18 37 7 15 12 481 394 131 79 48 3821 36 20 32 0-87 0-97 1*58 0*89 0-71 0*95 143 016 M2 1*88 1*63 1-03 081 080 140 0-86 0*88 072 065 091 Ml 1*04 Ml 1*45 0-89 (95% cn (079-0-95) (680-M7) (0-73-3-43) (0-30-2*66; (0-19-2*70 (0-67-1 33) (0*71-2-85) (0-02-1-24) (0-27-4-76) (682-4*31) (0-70-3-79) (0-42-1-73) (0*30-2-22) (0-38-170) (0-48-4-07) (0-74-1-00) (074-1-04) (0*54-0-96) (045-0-92) (0*54-1-52) (0*71--1-73> (0-46-3-36) (0-63-189) (0-34-3-88) (047-1-69) Police 9 United States white mm Deaths SMR ( 95H Cl) 714 0*87 (681-693) 169 0-95 (0*81-1-11) 8 0-50 (Q-22-699) 3 Ml (0-36-2*59) 4 1*40 (0'3fr-3'59/ 55 0*92 (0*69-1*19) a 1*03 (0*51-1*82) 4 0-91 (0*25-2*34) fl4 0*94 (626-2-41) 1-14 (0-49*2-25) 8 1-36 (0*59*2*69) 21 1*22 (0*75-1 86) 5 1*72 (036-103) 11 1*56 (0*76-2*80) 5 0:93 (0*30-2*17) 269 0*65 (0*75-696) 28263 1-230*86 (0*75-098) (1*00-1*55) 59 128 , (0*98-1*63) 25 1*24 (0-70-2-04) 30 0-M (0*43-0-91) 10 0*60 (0*29-1*11) 20 0*68 (0*42-1*06) 5 0*63 (0-20-1-46) 13 0*83 (0-47-1*37) of the arteries, veins, and pulmonary circulation (SMR = 2-55,95% Cl 1 43-3-38), and colon cancer (SMR - 1 69, 95% CX 0-77-3-20). Lagging also further accentuated the risks for emphysema among firefighters with 20 to29yearsofexposed employment (SMR 1-49,95% a 0-80-2-56). Firefighters with at least 30 years since their first employment had increased risks for brain tumours (SMR 2-63), lymphatic and haematopoietic malignancies (SMR -- 1-48), prostate cancer (SMR = 1 42), diseases of the arteries, veins, and pulmonary circulation (SMR * 133), and emphysema (SMR = l-39)(table5).Thesefirefighters also had an increased risk for brain tumours (IDR - 3 62, 95% Cl 1-2-11-2), prostate cancer (IDR = 1-58, 95% Cl 0-8-3-2), and emphysema (JDK = 1-48, 95% Cl 0-6-3-9) compared with police. In general, the risk for mortality from most causes was highestamongfirefighters 65 years ofageor older (table 6). Firefighters under the age of 40, however, had an SMR for all cancers of 1-45 (95% Cl 0-81-2 39) due primarily to a greater than expected number of brain tumours (SMR -- 3-75) and lymphatic and haematopoietic malignancies (SMR m 1 -74). The excess observed for cancer is by contrast with the deficits found for all non-cancer causes ofdeath (SMR ** 0-47). The excess ofcancer among firefighters under the age of40 persisted when the comparison was made with police (IDR -- 1-51, 95% Cl 0-7-3-5). Diicutsion Wc found an excessofbrain tumours among firefight ers compared with United States white men and police. Previous studies of workers exposed to vinyl chloride, acrylonitrile, and polycyclic aromatic hydrocarbons have noted excesses of braiihcancer." Although it is difficult to quantify, it is likely that Table 4 Seattle, Portland, and Tacomafirefighter mortality by duration ofexposed employment: 1945-99 Cause ofdeath * Colon cancer Ptostste cancer Brain and nervous system tumours Lymphsuc/fcaanatopoittic cancers Leukatmi* Disease* of the arteries, veins, and pulmonary circulation Chronic respiratory discaiaa flxphyimu <10 yean iO^iUjmrj 20-39years 1 1 Deaths SMR <95% Cl) Deaths SMR (95% Cl) 4 1 40 (0*4-3*6) 2 0*54 (0-1-2-0) 9 0-62 3 242 (65-71) 2 M2 (O'1-4*1) 14 1-23 3 2-57 (0-8-66) 8 3*53 (1-5-7-0) 6 124 4 0*91 (0-2-2-3) 7 1*46 (0*06*3-0) 14 1-06 2 1*13 fo-i-a-i) 2 1-04 (61-3*7) 4 673 4 1-36 (0-4-3-J) 4 0*94 (0*3-2-4) 15 0*79 2 0-42 (01-1-5) 5 0*82 063-1*9) 34 1 15 1 0-92 (0*1-3'1) 3 1*83 (64-4-3) 12 1 35 >30years : (95% Cl) Deaths SMR (9S% CU (63-1*2) (67-2-1) (65-27) CO-6-1'8) CO-2-1'9) (64-1*3) 9 11 3 12 7 25 1*21 1*36 2 04 205 260 1*99 (0-6-2-3) (67-2-4) (64-5*9) (1-1-3-6) (1-0-54) (13-2*) (0-8-1-6) 13 (0-7-64) 4 697 00-5-1*6) 0-76 (0-2-1-9) < k i 1 j i i I i i I j t t I Material may be protected by copyright law (Title 17, U.S. Code)  --' 668 Demurs, Heyefi Rosewtock Table $ Seat*!*, Portland, and Tacomafirtfffliur mortality byyears tint#first employment; 1945-89 <20years 20-29years ^30years Cause ofdeath Cotoo cancer Proet&te c*nccf Brain and nervoufi system tumours Lymphatfc/haematopoieric cancers Leukaemia - - Disease* of the arteries, reins, and pulmonary drculsuoo ironic respiratory diseases Emphysema Deaths SMR l 0-51 0 0-00 6 2-45 a 1-63 13 1*50 0-51 ] 045 0 000 r mm co ruatht SMR (0-1-20) 3 (0 0-26-6) 0 (0'9-5*3) 2 (07-3*3) 2 (03-4-4) i (0-1-2-8) 4 0-66 0-00 0-73 0-39 0-50 0*91 (0-1-2-5) 2 (00-7-9) 0 0-32 0-00 <95% Cl) Death! SMR (01-1-9) (0-6*31) (0-1-2*6) S'1-1-4! (01-2-8) (0-2-2-3) 20 30 14 27 11 43 0-91 1-42 263 1-48 1-40 1-33 53 (60-1-8) 20 M2 1-39 fPJW Cl) (0-6-1-4) (1-0-20) (14-4-4) (1-0-2-2) (0*7-3-5) (i-0-18) (0-8-1-5) (00-2-2) exposure to polycyclic aromatic hydrocarbons at fires is common whereas exposure to vinyl chloride and acrylonitrile may happen only under certain condi tions. If the excess of brain cancer were due to exposures that were not necessarily present at most fires, this might at least in part explainourfinding that duration of exposed employment was not associated with increasing risk. We also found an excess risk of leukaemia, which was highest among persons employed 30 or more years in fire combat positions, confirming our earlier finding of an increased risk among Seattle firefight ers." A twofold excess of multiple myeloma relative to police was also found. Other studies have noted an excess of lymphatic and haematopoietic cancers of various histologies"11 11 " and an excess of these malignancies is plausible given the exposure of firefighters to benzene.Although exposure to benzene is likely to be short term, measurements have been taken in excess of 100ppm." Our ability to conclude with certainty an association with exposure to fire smoke is limited by our finding of a similar excess in police. We arc unable to assets whether the excess among police is due to factors held in common between the two occupational groups, to some exposure unique to police, or to chance. Of interest, two other studies that have examined cancer in firefighters o police found firefighters to be at higher risk for leukaemia.11" We alsofound anexceasofprostate cancer, aneffect ofuncertain significanceand not seen in other studies. The persistence of this excess compared with police makes a diagnostic bias an unlikely explanation. We did not find excess cancers of the skin, bladder, or lung, which have been noted in some other studies of firefighters. Limitedsupportwasfoundforpreviously described excesses of colon cancer when the comparison was made with police, but not with the United States reference group. The inconsistency with previous studies may be due to the small number of deaths found foT some sites or to the different methods used and varying time periods examined. As anticipated, many ofthe results ofthis study are consistent with the healthy worker effect. One excep tion was deaths due to diseases of the arteries, veins, and pulmonary circulation, which were increased among firefighters with at least 30 years of exposed employment compared with both United States white men and police. This result is difficult to interpret given the heterogeneous nature of conditions in this category. In analyses ofthis cohort performed with followup through 1983 we found an excess of non-malignant respiratory disease compared with police (IDR 1-59), as opposed to a deficitwhencompared with United States rates (SMR -- 0-88).* One other study that compared deaths from lung disease in firefighters with those for police officers found a similar result.11 Although this disparity was also found in the current analysis, the magnitude qf the effect was much reduced. This may be in 'part Tablt 6 Seattle, Portland, and Tacomafirefighter mortality by oft at ride: 1945-39 Cmae ejdeath CbkML cancer Prostata cancer Bmin and nervous system tumours Lymphstk/haematbpoietic cancers Leukaemia Diseases ofthe ureries, veins, and milmwiary Chrome nayittuxr dteua EmphyKOU - 18-39yean old 40-64yean old >65 years old Deaths SMR (WM Cl) Deaths SMR (95% Cl) Deaths SMR I 1-38 (01-6-2) 10 0-78 (04-1-4) 13 0*86 0 0-00 (0-0-178) 4 086 CO-Z-J-2) 26 1-46 5 3-75 (i*2-8*7j 11 1-66 (00-3*0) 6 234 5 1-74 (0-6-4* 13 096 (05-1*6) 19 1-61 l 0-82 (0-1-4 6) 5 095 (0-3-3*2) 9 1-67 l lit (01-6-8) 7 0-56 (Oa-i-i) 40 1-58 1 Ml (0-1-6*2) 7 0-36 (01-0*7) 48 136 Q 000 (0*0-37*2) 3 OSO (00-1*5) 17 1-57 (95% Cl) <0-5-1 *5) (l-O-a-l) (0*9-50) (10-2-5) (0*8-32) (1-1-21) (1014) (09-2*5) MortaHQ accounf U8< of I the risi disease: (SMR, (SMR Noni founds States OCCUTTI employ 29 year exist be the foci with 30 be due employ conclus specific betweei Wberea disease: emphys Stunt interprt duratkx improvi may sti particui all fires , andwitl being t , available seen be andvari , to then Anotl accurac; death oi hing dis cause of Informs lacks di subaite thatacw etiologic the expi obscuret Police populate otnic stag required firesmoH by accug similar," of the mb risk estjf Material may be protected by copyright law (Title 17, U.S. Code) :yer, Rosenslock 4R (95% Cl) >1 (0-6-14) \% (10-20) (1-4-44) IS 0*0-2 2) 10 (0-7-2-5) (1-0-18) 12 (Q&-1-5) 19 (0-9-2-2) cd with police planation. We n, bladder, or ther studies of .for previously ;r when the t not with the inconsistency to the small ites or to the time periods fthis study are ct. One excep* arteries, veins, rere increased its of exposed United States h is difficult ms nature of with follow up tan-malignant with police hen compared 8)." One other mg disease in Boers found a trtty was also gnitilde of the ly be in pan old MR (9S% Cl) 86 (0-5-1 *3) 46 (1-0-2*1) 34 (0-l) 61 0*0-2*5) 67 (O-e-3-2) 5B (i-i-J-1) 36 Cl-0-1-8) 37 (0-9-2 5) Mortality amongfirefightersfrom three northwestern United Slates cities 669 accounted for by the increasing availability and stability and their confidence limits are correspond use of respiratory protection since the 1970s. Also, ingly wide. Also, police have rarely been studied and the risk of death due to non-malignant respiratory their occupational exposures and risks for death due II disease among police was higher in the current to various causes have not been well characterised. (SMR -- 0-64) than in the earlier analysis An excess or deficit of deaths among police could be (SMR - 0-48). due to their own unique exposures or characteristics None the less, a raised risk of emphysema was and thus lead to spurious conclusions about firefight found among firefighters compared with both United ers. Potential police exposures include psychological States white men and police?'All of these deaths stress and motor vehicle exhausts. The magnitude occurred among subjects at least 30 years after first and health effects of these exposures arc not fully employment and was highest among those with 10 to known and their potential for introducing bias 29 years of exposed employment. If a relation does should be borne in mind. existbetween exposure to fire smokeand emphysema, In conclusion, this study found excesses of brain the fact that the risk was reduced among firefighters cancerand leukaemia among city firefighters from the with 30 or more years ofexposed employment might northwest United States and suggests that they may be due to those most susceptible to disease leaving be at excess risk of dying from emphysema. employment early due to disability. Attempts to draw Exposures to known carcinogens and respiratory conclusions should be tempered by the fact that the irritants are likely to explain these findings; future specificityofdeathcertificatesislowfordifferentiating efforts should be directed towards reducing and between different types ofobstructive lung diseases. eliminating these exposures. Whereas the results for all chronic respiratory diseases combined roughly parallel those for This research was funded through a cooperative emphysema, the risks were of lesser magnitude. agreement with the United States Fire Administra Some limitations should be borne in mind when tion ofthe Federal Emergency Management Agency interpreting the results of this study. Firstly, (BMW 85-K-2089). Paul Demers is supported by a 1 duration of fire combat employment, although an training grant in environmental epidemiology and improvement over total duration of employment, biostatistics from the National Institute for Environ may still be an inadequate measure of exposure, mental Health Sciences (T32 ES07262). We thank particularly for substances that may not be present at the Fire and Police Pension Boards, Departments all fires. Exposure may vary substantially between and Unions of Seattle and Tacoma, Washington and and within fires due to the composition ofthematerial Portland, Oregon, and Rebecca Hubbard. being burned, the temperature of the fire, and availability of oxygen.3 ' Thus the lack of association Requests for reprints to: Linda Rosenstock MD, seen between duration or fire combat employment Occupational Medicine Programme, ZA-66, and various outcomes in this study may in part be due University of Washington, 325 9th Avenue, Seattle, to the use ofa poor surrogate for exposure. WA 98104. Another limitation of this study is the lack of accuracy and specificity of information on cause of death on death certificates. In the case of heart and 1 National Rnceidi Council. Fire and smoke: understanding the hemsrds. Washington DC: National Academy Fret,, 1980. 2 Birky MM, Clarir FB. Inhalation of toxic product, from Arcs. lung disease it may be difficult to assign a specific fluff 2/ Y AeadMed 1981:57:997-1013. i cause of death without a postmortem examination. 2 Bnndt-Ranf PW, Fallon 1-F, TitramIni T. Idema C, Andrew, L.Health ba^rdiofhrctighten: exposure inrirmmt.HrJInd Information about canceron deathcertificatesusually Med 198805:606-12. lacks detail and only rarely includes anatomical subsite or histological Information. To the extent 0 Treitmin RD, Burgcsi WA, Gold A. Air contaminants enenumered by firefighters. Am Ind tiytt Asset J i980:41: 796-802. \ that a cause ofdeath category contains awide range of 3 Lainy WT, Juans L, Petty CS, et el. Studka offside gat 1 ! etiologically unrelated diseases, the relation between the exposure and any one specific disease will be production during actual structural Urea In the Dallas iru. 1 Formic Sd 19830054-72. \ 6 Bumb flit, CnuuneR WB, Cutie SS, et al. Trace chemJrtiic* of obscured. Police were chosen as an alternative reference Are; a source ofchlorinated dioxin,. Science 19800101183-90. 7 Hartiell OK, Packham SO, Stricter WG. Totdc product, from Are, Am Indnst Hyg Asnse J 198.V,44:24&-55. ' population because they have a similar socioecon omic state, health benefits, and strict physical entry 8 GoldA,Burges WA.aougherry EV. lixpoauieul fircfighler, m toxic air contaminants. Am Ind Hyg Assoc J 197809:534-9. 9 Vena J, Fiedler RC. Mortality in a municipal workers cohort: 4 requirements, and are generally free from any major IV. Are lighten. Am J IndMed 1987;11:671-84. fire smoke inhalation. Two studies of smoking habits 10 Ebomiltis E, Armamatg BK, Spickcrt JT, Heywonh F. Mortality 0f fire fighter* in Western Auser,ha. Hr J Ind Med by occupation show that police and firefighters are 196401:183-7, similar,1'M although a somewhat greater percentage 11 Office of Population Censuses and Survey*. Ocestpatlmal mortality, the Registrar General's decennial mppiemenl far offirefighters reportedhaving never smoked. Because Orem Britain. 1979-80,1982-83. London: RMSO, 1986. of the small number of police deaths, however, the 12 Sana SR, Martin TR, Diels LK, Kriebel D. Cancer incidence risk estimates based upon them lack statistical Ibamt Maasochusctt* fbefighteta, 1982-1986. Am J Ind Med 199008:47-54. 4 1 ?1 J ! i Material may be protected by copyright law (Title 17, U S. Code) 670 Dtmon, Htyor, Rosenstock 13 BeaumontJl, Chu GST, Jones JR, efal. An cpidemiologfe study of mortality from cancer and other causes in San Francisco firefighters. Am J Jnd Med 1991;19:397-72. 14 Feucrfi,RraemnanK.MormUtympoliccandlirefiKhmrsinNew Jersey. AmJlnd Mid 1986;9:517-27. 15 Howe GR Burch JD. Fire fights* end risk of cancer; an assessment and overview ofthe cpidankrionc evidence. Am J EpUmmUA 1990;132:1039-90. 16 H*n*en ES. A cohort study on the morality offirefighter*. Bt J IndMtd !990i47;805-9. 17 Kfrkpscrkk M, Bass J. Severe obstructive lung disease after smoke inhalation. Chtn 1979;7S;J 06^10. 18 Lokc J. Farmer W, Matxhay R Putaun C* Sndth G, Acute and chronic effect* of firefighting on pulmonary function. Choel 1980;77:369-73. 19 Whitener DR, Whitencr LM, Robertson KJ, os al. Pulmonary America measurements of patient* with tbeireal injuries and onoke inhalation. AmRtv Rtspir Du 1980;122:731-9. 20 PctersJA^TheriflutcGPfFlneLJfWegnianDfLChrnniceffects of firefighting on pulmonary funetjeu. JV Entl J Mod 1974491:1325-2. 21 Unger K, Snow R. Mcrta* J, Mijle W. Smoke inhalation in firemen. Thorax z960{35:83b-42v 22 Sparrow D, Boate R* Rosner B, Wdh S. The effect* Of occupational exposureon pulmonary function--* longitudinal evaluation of firsfightert and non-fireftghten. Am Rev Rapit DU 1982;133:319-22. 23 Musk A\P Peters JM, Berstein L, Rnbin C, Mooroe CB. Pulmonary function in firefighters III: a tig year follow-up in die Boston Fire Department. Am J fad Mod 19820:369-73. 24 Radford HP, Levine MS. Occupational exposure to carbon monoxide In Baltimore firefighter*. / Occup Mod 1976} IS: 628-34. 26 Goldsmith JR, Anmow WS. Carbon monoxide and coronary heart disease: A review, Bmn'rm Rot 1975;10:236-48. 26 MonsouRR.Observatloitsoin thehealthy worker effect../Oca# Mod 196608:425-33, 27 Fox AJ, Collier PF. Low mortaliiy rates in industrial cohort studies due to relection for work and survival in the industry, Britith Journal oj Prwmtm and Sodd Modktoo 197600; 225-30. 28 Gilbert B5. Some confounding factors in die study ofmorality and Occupational exposures. Am J Epidemiol 1982:116: 177-88. 29 Rosenscock L, Demers P, Hcyer NJ, Barnhart $. Respiratory morality among firefighter*. Bt J Ind Med 199007:462-$. 30 Heyer N, WeiuN, Damn P, Brcslow N, Rasenstock L. Cohort mortiHty truly of Seattle firefighter*: 1945-1983, Am J Jnd Mod 199047:^93-504. 31 Marsh GM, Preiifinger M. OCMAP: a userorknted occupational mortality analysis program, ^mrinn Statutuian 1980:34:245. 32 Kkinbaum DG, Kupper LL, Morgenstcm H. Epidemiologic research: principle* and quantitative methods. Mew York: Von No*trend Reinhold, ly82. ' 33 Checkoway K, Petra N, Hickey JL, Dement JM. Latency antlysii in occupational epidemiology. Arch Environ Hoaltk 199005195-100. 34 Thomas TL, WnweUer RJ. Brain tumors and occupation*! ri*k heton: a review. StandJ Work Environ Health 198ti;12:1-15. 95 Bracfcbili B, FnzierT, ShillingS. Smokingcharacteristics ofU$ workers 1978-80, Am J InfMod 198803:5-42. 36 StalliniinSDfllofllsttaPjGaHlftkelL.SnicildTigliaWtiofeOO^OOO American men in relation (o their occupation. Am J tnd Mod 198843:43-58. Accepted 2 December 1991. Britufu coi Pratpi blood Sit,-! IMS); the on! gearing ooocen nancy, soon: who ei during: ingperi after he concern her infl noted lopathy specula increase pregnai' lead so our two increase during] i-af a*. '? Kji . tJ 1*11 *0 10-0 *0 0-0 Material may be protected by copyright law (Title 17, U.S. Code)