OCCUPATIONAL EXPOSURE AS A PAINTER
2. Studies of Cancer in Humans
2.1 Cohort, record linkage and proportionate mortality studies .1 Background .1 Background
In 1989, the International Agency for Research on Cancer (IARC) classified painting as an occupation as carcinogenic to humans (Group 1) (IARC, 1989, Volume 47). At the time, the epidemiological evidence for the evaluation was primarily based on a total of eight studies (five record linkage and three cohort studies), listed in Table 23 of that volume. The primary findings in these data were relatively consistent excesses for all cancers (standardized mortality ratio [SMR] 1.21, 9100 cases), and for cancer of the lung (SMR 1.41, 468 cases). The lung cancer excess was noted to be above what could reasonably be expected to be due to confounding by smoking. Other findings which drew comment in Volume 47 were excesses for cancers of the oesophagus, stomach, and bladder, although these excesses were smaller than for cancer of the lung and were less consistent across studies. It was noted that results from a few studies showed excesses of leukaemia, and cancers of the buccal cavity, and of the larynx.
Cohort studies generally represent a stronger study design than record linkage studies.
In the latter, the exposure is often taken from census employment data, is typically less accurate than the employment records upon which cohort studies are usually based, and does not usually take into account duration of employment. However, in the case of the cohort and record linkage studies listed in Table 23 by IARC in 1989, findings from both types of studies were reasonably consistent.
2.1.2 Cohort studies since IARC Monograph Volume 47 (Table 2.1)
Yin et al. (1987) studied workers who were employed at least 6 months within different factories in the People’s Republic of China. They compared 13 604 benzene-exposed painters to 28 257 production workers without occupational benzene exposure with a similar sex and age distribution. Mortality follow-up occurred from 1972–1981, and the authors presented the leukaemia mortality rates separately for painters (15.9/100 000 person–years) and the comparison cohort (2.01/100 000 person–years). [The painters, not including paint-production workers, had a mortality rate ratio of [7.9] (14 leukaemia deaths) compared to workers in other production jobs without benzene exposure (four leukaemia deaths). This high rate ratio is presumably due to the selection of these painters for specifically benzene exposure.] No other cancer outcomes were presented.
Hrubec et al. (1995) followed a cohort assembled from a roster of approximately 300 000 caucasian, male WWI and WWII veterans for mortality from 1954–1980. These men served in the US Armed Forces at some time during 1917–1940, and held active
170 IARC MONOGRAPHS VOLUME 98
government life insurance policies. Personal data on usual occupation and smoking habits were obtained by mailed questionnaire in the 1950s. SMRs were calculated using Poisson regression, using all other occupations as the reference. After adjustment for smoking, age and calendar time, 1178 construction and maintenance painters had an SMR for all cancers of 1.0 (90% CI: 0.84–1.11, based on 140 cancer deaths). Cancer mortality was not remarkable for most anatomical sites. For anatomical sites with more than five deaths, the SMRs were 0.8 (90% CI: 0.42–1.61; six deaths) for cancer of the stomach, 1.0 (90% CI:
0.69–1.51; 18 deaths) for cancer of the colon, 1.6 (90% CI: 0.89–2.86; eight deaths) for cancer of the rectum, 1.1 (90% CI: 0.84–1.47; 36 deaths) for cancer of the respiratory system, 0.5 (90% CI: 0.27–0.78; ten deaths) for cancer of the prostate, 0.9 (90% CI: 0.48–
1.67; seven deaths) for lymphoma, and 1.2 (90% CI: 0.69–2.10; nine deaths) for leukaemia.
A smaller number of non-construction painters (n = 140) provided little extra information on cancer mortality owing to the small numbers involved.
Alexander et al. (1996) conducted a cohort study of 2429 chromate-exposed workers in the aerospace industry, of whom 62% had ever worked as a painter. A total of 15 cases of lung cancer were observed among the entire cohort, which was less than expected based on incidence data (SIR, 0.8; 95% CI: 0.4–1.3). No exposure–response trends with hexavalent chromium was seen, although the number of cases of lung cancer were too small to draw any meaningful conclusions. There was an inverse trend of lung cancer with duration of employment for painters, although sanders and polishers (exposed to dusts rather than mists) had a somewhat positive trend with duration. None of these results were statistically significant.
van Loon et al. (1997) conducted a population-based cohort study in the Netherlands that prospectively followed 58 279 men, aged 55–69 years, for cancer incidence from 1986–
1990. Rate ratios were estimated by a case–cohort analysis (524 cases, 1630 non-cases in the subcohort). Self-reported lifetime job history, reviewed by experts on a case by case basis, was used to create a job exposure matrix (JEM) for exposure to paint dust (none, low, high). Positive non-significant increases in lung cancer were found for the ‘low’ exposed group (RR, 2.29; 95% CI: 0.61–8.63) and the ‘high’ exposed group (RR, 2.48; 95% CI:
0.88–6.97) compared to the unexposed group, after adjustment for age, smoking, diet, and other occupational exposures; although the test for trend was significant (P < 0.01). [This study was limited owing to the small sample size (14 ‘high’ and ‘4’ low exposed lung cancer deaths) and the use of a JEM to assign exposure level based on self-reported employment information.]
Boice et al. (1999) conducted a retrospective cohort study among 77 965 aircraft industry employees in California (1216 painters), employed for at least one year on or after 1960, with registry-linked mortality follow-up through 1996. There was little detail available on the type of painting done, except that the paints contained chromates. There were 101 cancer deaths among painters (all cancer SMR, 0.87; 95% CI: 0.71–1.06). The SMR for cancer of the lung was 1.11 (95% CI: 0.80–1.51; 41 deaths).
OCCUPATIONAL EXPOSURE AS A PAINTER 171 Table 2.1. Cohort, linkage and proportionate mortality studies of painters published since Monograph Volume 47, 1989
Reference, location, time period
Cohort description Exposure assessment benzene-exposed workers in China employed in factories > 0.5 yrs during 1972-81;
leukaemia mortality follow-up 1972-81;
controls were 28 257 workers not occupationally exposed to benzene
Information on occupational history, history of benzene poisoning,
Mortality rate ratio
= 7.9 had similar age and sex
1178 painters were followed during 1954–80 within a cohort assembled from a roster of approximately 300 000 white male WWI veterans who served in the US Armed Forces some time during 1917–40 and who held active government life insurance policies
Mailed
questionnaire that inquired about tobacco use, usual industry of employment and occupation, coded using 1950 Census Occupation and
172 IARC MONOGRAPHS VOLUME 98 Table 2.1 (contd)
Reference, location, time period
Cohort description Exposure assessment employed >6 months in the aerospace industry during 1974–
94 were assembled from company work-history records; 62%
had ever worked as a painter; incidence follow-up 1974–94 with linkage to the SEER registry;
median 42 yrs of age
Exposure to chromium [VI] was estimated from using the Puget Sound population during 1974–
94 as reference
No information on smoking; no trend with cumulative exposure to chromium (VI) but slightly positive trend with duration of employment as a sander/polisher;
69 yrs, enrolled from the general Dutch population and followed for lung cancer incidence from 1986–90 by linkage to national and regional registries
Paint exposure was obtained from job history as part of a self-administered questionnaire and case by case expert assessment
Lung Low exposure
to paint dust
No paint exposure was the reference;
cumulative
OCCUPATIONAL EXPOSURE AS A PAINTER 173 Table 2.1. (contd)
Reference, location, time period
Cohort description Exposure assessment
1216 painters (1139 men, 77 women) employed >1yr in the aircraft industry, followed-up retrospectively for mortality
Detailed job history was obtained from work-history
Other cancer causes non-informative due to small numbers of deaths; painting not described in detail except that paints contained
42 170 painters and 14 316 non-painters with >1 yr union membership were identified from union records and followed from 1975–94 by linkage to national and local registers;
Restricted to white men (98% of the cohort).
Job titles were inferred from union membership records which identified the specialty affiliation and trade of the local union for all members
No information on trade of individual members; SMRs
174 IARC MONOGRAPHS VOLUME 98 Table 2.1. (contd)
Reference, location, time period
Cohort description Exposure assessment
69 yrs, were enrolled from the general Dutch population and followed for bladder cancer incidence from 1986–92 by linkage to national and regional registries
Paint exposure was obtained from job history as part of a self-administered questionnaire and case by case expert assessment
Same Dutch cohort as that described in van Loon et al.
69 yrs, were enrolled from the general Dutch population and followed for bladder cancer incidence from 1986–92 by linkage to national and regional registries
Paint exposure data obtained from job history as part of a self-administered questionnaire, and job titles were coded using the Dutch Occupation Classification system
Prostate Ever painter
Painter as one’s usual
Same Dutch cohort as that described in van Loon et al.
1960 Swedish census linked to the Swedish Cancer Registy to follow-up for bladder cancer incidence from 1961–79
Occupations and industries obtained from the 1960 census and coded using ILO standards.
Bladder Painter as one’s specific
No adjustment for smoking.
The census code not given for ‘artistic painters’ and thus may correspond to the Swedish
‘pictorial artists’
studied in Brown et al. (2002)
OCCUPATIONAL EXPOSURE AS A PAINTER 175 Table 2.1. (contd)
Reference, location, time period
Cohort description Exposure assessment national census, aged 30–64 years and gainfully employed, were linked to the Swedish Cancer Registry and followed for cancer incidence from 1961–79
Occupations and industries were obtained from the 1960 census and coded using ILO standards. Smoking data were obtained from a large survey among an age-stratified random sample of the Swedish population in 1963
Lung Painters and
paperhangers 425
SIR (95% CI) painters or may also paint, and it is reasonable to consider this category as a whole as ‘painters’. This study population overlaps with that of Malker et al.
Persons aged 20–64 years in the 1970 Danish census linked to the national cancer registry and followed for cancer incidence through 1980
Data on industry and occupation captured in the 1970 census. Industry coded using ISIC codes and occupation coded using a special Danish code.
Pharynx All painters
(n = 19163) Skilled workers, painter in paint workshop (n = 9703) Self-employed, painter in paint workshop (n = 5150) Skilled workers, painter in metal industry (n =
176 IARC MONOGRAPHS VOLUME 98 Table 2.1. (contd)
Reference, location, time period
Cohort description Exposure assessment
1916 male painters from the 1970 Geneva census were linked to the Geneva Cancer Registry and followed for cancer incidence during 1971–84
Occupational classifications were obtained from the 1970 census painters showed a significant excess mortality from alcoholism (SMR, 6.25; 90%CI: 2.46–
13.14; 5 deaths) and a borderline significant excess
2.1 million men and 820 000 women aged 20–69 years and gainfully employed obtained from the 1960 Swedish population census and linked to the Swedish Cancer Registry to follow for cancer incidence from 1961–
79
Occupations and industries obtained from the 1960 census and coded using ISIC and ILO standards population used as the reference.
Nearly the same design as used in Carstensen et al.
(1988) but did not adjust for smoking.
This study population overlaps with that of Malker et al. (1987)
OCCUPATIONAL EXPOSURE AS A PAINTER 177 Table 2.1. (contd)
Reference, location, time period
Cohort description Exposure assessment
Male British painters, aged 25–64, who died from bladder cancer during 1965–80
Information on occupation and industry of usual employment was extracted from death certificates and coded according to British standards smoking data that were unavailable
Firth et al.
(1993) New Zealand
Male cancer deaths during 1973–86 obtained from the New Zealand Cancer Registry and linked to census data from 1976, 1981, and 1986
Occupation obtained from census data and coded using the New Zealand
Only select findings reported
87 004 economically active, male painters and lacquerers included in the national census of 4 Scandinavian countries were followed-up for cancer incidence by linking individual records with national cancer registries by birth cohort, site and sex
Entire census population used as a reference
178 IARC MONOGRAPHS VOLUME 98 Table 2.1. (contd)
Reference, location, time period
Cohort description Exposure assessment
29 689 male painters and decorators, aged 20–74 years, who died during 1979–80 or 1982–90, linked to census denominators
decorators 4110 75 female painters and wallpaper hangers, aged 25–64 years at 1970 censuses, were followed-up for cancer incidence during 1987–91 by linkage to national cancer registries
Occupation was obtained from census data and coded according to national adaptations of the Nordic Occupational Classification or according to a special Danish Multiple myeloma (ICD-7, 203) and wall paper hangers and time period
National populations as the reference.
The Swedish component partly overlaps Brown et al. (2002) who also included painters from the 1960 Swedish census.
Also overlaps the 4-country study by Skov et al. (1993), who reported on fewer cancer sites with shorter follow-up
OCCUPATIONAL EXPOSURE AS A PAINTER 179 Table 2.1. (contd)
Reference, location, time period
Cohort description Exposure assessment 1965–71 and who completed employ-ment surveys linked to the Canadian mortality database for follow-up during 1965–91
Occupation (≥1 year) obtained from employment surveys and coded using standardized
People in the painting trades or painting industry (42 433 male painters and 6662 male and 2136 female pictorial artists) obtained from 1960 and 1970 Swedish census data were linked to the Cancer Environment Register to follow-up for cancer incidence from 1971–89
Job title and industry were obtained from census data and coded using
Extra hepatic bile ducts
Larynx Non-Hodgkin lymphoma Hodgkin disease Multiple myeloma Leukaemia
Male painters (classified either in 1960 or 1970)
548
Bladder cancer risk was significantly increased by about the same magnitude in male and female artists, although this association was not significant in women. Female artists were at increased risk of cancer of the uterus. Lung cancer risk was not increased among artists
180 IARC MONOGRAPHS VOLUME 98 Table 2.1. (contd)
Reference, location, time period
Cohort description Exposure assessment
Proportionate mortality studies Miller et al.
630 caucasian male painters were identified from a registry of death certificates of 1757 artists deceased during 1940–69
Artists identified
from obituaries Bladder Leukaemia
Total number of cancer deaths for all sites combined was used as the comparison group.
The PMR for lung cancer was not significantly recorded at the time of cancer class, region of registration
29 689 male painters and decorators, aged 20–74 years, who died during 1979–80 or 1982–90, linked to census denominators
Last full-time occupation was obtained from death certificates
Data for 1981 were omitted because of questionable quality
OCCUPATIONAL EXPOSURE AS A PAINTER 181 Table 2.1. (contd)
Reference, location, time period
Cohort description Exposure assessment
British painters, aged 16–74 years, who died during 1979–80 and 1982–90 were obtained from a UK register
Last full-time occupation obtained from death certificates
Mesothelioma Male painters and decorators 100
PMR (P-value) 1.31 (P<0.05)
Age, calendar year
This study partially overlaps with the Registrar General’s
9812 Dutch male painters identified from a registry and deceased during 1980–92
Painters obtained from a registry with which nearly all commercial painters
painters 3266 1480
Total Dutch male population during 1980–1992 used as a comparison
All male construction workers who lived and died in North intervals or number of deaths provided
CI, confidence interval; ILO, International Labor Office and the United Nations Statistical Office; ISIC, International Standard Industrial Classification; NG, not given;
PCMR, proportionate cancer mortality ratio; RR, rate ratio or relative risk; SIR, standardized incidence ratio; SMR, standardized mortality ratio; TWA, time-weighted average
182 IARC MONOGRAPHS VOLUME 98
Other cancer categories had very few deaths and provided little information. More detail can be found in Table 2.1.
Steenland & Palu (1999) updated a previous large cohort study of US painters by Matanoski et al. (1986): 42 170 painters and 14 316 non-painters were assembled from union records and followed for mortality through local and national registries from 1975–
1994. The update added 15 years of follow-up during which time the number of deaths increased from 5313 to 23 458. When painters were compared to the general US population, the updated data showed significant but modest excesses for all cancers (SMR, 1.12; 95%
CI: 1.09–1.15; 4674 deaths), cancers of the lung (SMR, 1.23; 95% CI: 1.17–1.29; 1746 deaths), of the bladder (SMR, 1.23; 95% CI: 1.05–1.43; 166 deaths), of the stomach (SMR, 1.39; 95% CI: 1.20–1.59; 197 deaths), and of the liver (SMR, 1.25; 95% CI: 1.03–1.50; 119 deaths). In an additional analysis comparing painters and non-painters directly at other anatomical sites, the standardized rate ratios (SRRs) were 1.23 (95% CI: 1.11–1.35) for cancer of the lung, 1.77 (95% CI: 1.13–2.77) for cancer of the bladder, 0.92 (95% CI: 0.68–
1.25) for cancer of the stomach, and 1.36 (95% CI: 0.87–2.11) for cancer of the liver.
Further analyses restricted to painters with at least 20 years of membership in the union, showed reductions in the SRRs for cancers of the bladder, stomach, and liver while the SRR for cancer of the lung increased slightly (to 1.32). Both painters and non-painters showed significant excesses of cirrhosis compared to the US population (SMRs, 1.21; 95% CI:
1.07–1.35, and 1.26; 95% CI: 1.03–1.51, respectively), suggesting an excess of alcohol consumption compared to the US population; nonetheless, as noted above, the excess of liver cancer persisted in a direct comparison of painters to non-painters.
The data were also adjusted indirectly for smoking using detailed information on smoking in the general population from two large US surveys (see Axelson & Steenland (1988) for the description of methods). The authors found that confounding by smoking when comparing painters to the US population would have resulted in a rate ratio of 1.14 for lung cancer and 1.05 for bladder cancer, compared to the observed SMRs of 1.23 and 1.23, respectively. While this suggested that confounding by smoking may have accounted for some of the lung cancer excess, the case for an occupational etiology was strengthened by the finding of an SRR of 1.23 (95% CI: 1.11–1.35) through a direct comparison painters to non-painters in the same union as both these groups were expected to have similar smoking habits.
The same Dutch cohort described by van Loon et al. (1997) was studied for incident cancers of the bladder (532 cases, 1630 subcohort members) and of the prostate (830 cases, 1525 subcohort members), using the same case–cohort design (Zeegers et al., 2001, 2004).
Using a case by case expert assessment, and adjustment for age, other occupational exposures as well as the amount and duration of cigarettes consumed, a positive trend for exposure to paint components was observed, with incident rate ratios of 1.00, 0.75 (95% CI:
0.33–1.72), 1.78 (95% CI: 0.94–3.37), and 1.31 (95% CI: 0.72–2.40) for increasing levels of estimated exposure (none, low, medium and high, respectively; P-value for trend, 0.09), based on 483, 8, 20, and 19 bladder cancer cases, respectively (Zeegers et al., 2001). For the 765 prostate cancer cases that reported occupational history, job titles were coded using the
OCCUPATIONAL EXPOSURE AS A PAINTER 183 Dutch Occupational Classification system. Incident rate ratios were presented for ever being a painter (RR, 1.10; 95% CI: 0.39–3.08; 12 cases), and for being a painter as one’s usual occupation (RR, 1.28; 95% CI: 0.31–5.30; seven cases), after adjustment for age, diet, cigarette and alcohol use, family history of prostate cancer, education and physical activity (Zeegers et al., 2004).
2.1.3 Record Linkage studies since IARC volume 47 (Table 2.1)
Malker et al. (1987) conducted a record linkage study of bladder cancer in Sweden, linking the 1960 census with the Swedish National Cancer Registry to follow up for cancer incidence from 1961–1979. Age- and sex-specific bladder cancer incidence rates for painters were compared to the general Swedish population cancer incidence rates. They found no excess of bladder cancer in painters (SIR, 1.00; 186 cases; adjusted for age and region), but an elevated risk in artistic painters (SIR, 1.70; P < 0.01; 42 cases). [The census code corresponding to ‘artistic painters’ is not given and thus it is not clear if this corresponds to Swedish ‘pictorial artists’ (census code 081) as in the study by Brown et al.
(2002). The results were not adjusted for smoking.]
The Swedish Cancer-Environment Registry was used to evaluate occupational risks of renal cancer (McLaughlin et al., 1987). This is a record linkage study involving the Swedish Cancer Registry with employment data from the national census. For this study employment data came from the 1960 census and cancers were diagnosed between 1960 and 1979. Among Swedish men there were 7405 cases of renal cell cancer and 821 renal pelvis cancer. Standardized incidence ratios (SIR) were calculated based on national cancer incidence rates. The SIR from painting and paperhanging, adjusted for age and geographic region, was 0.94 for renal cell cancer, and 0.69 for renal pelvis cancer.
The Swedish Cancer-Environment Registry was used to evaluate occupational risks of renal cancer (McLaughlin et al., 1987). This is a record linkage study involving the Swedish Cancer Registry with employment data from the national census. For this study employment data came from the 1960 census and cancers were diagnosed between 1960 and 1979. Among Swedish men there were 7405 cases of renal cell cancer and 821 renal pelvis cancer. Standardized incidence ratios (SIR) were calculated based on national cancer incidence rates. The SIR from painting and paperhanging, adjusted for age and geographic region, was 0.94 for renal cell cancer, and 0.69 for renal pelvis cancer.