Carcinogens in the Construction Industry

Carcinogens in the Construction Industry BENGT JÄRVHOLM Department of Public Health and Clinical Medicine, Umeå University, SE-901 85 Umeå, Sweden ABSTRACT: The construction industry is a complex work environment. The work sites are temporary and rapidly changing. Asbestos has been widely used in construction industry, but the risks were primarily detected in specialized trades, such as insulation workers and plumbers. Today, the majority of cases related to asbestos exposure will occur in other occupational groups in the construction industry. In a large cohort of Swedish construction workers, insulators and plumbers constituted 37% of all cases of pleural mesothelioma between 1975 and 1984 while they constituted 21% of the cases between 1998 and 2002. It is estimated that 25 40% of all male cases of pleural mesothelioma in Sweden are caused by asbestos exposure in the construction trades. There are many other known carcinogens occurring in the construction industry, including PAHs, diesel exhausts, silica, asphalt fumes, solvents, etc., but it is difficult to estimate exposures and thus the size of the risk. The risk of cancer is less easy to detect with traditional epidemiological methods in the construction industry than in other industrial sectors. It is not sufficient to rely upon broad epidemiological data to estimate the risk of cancer due chemicals in the construction industry. Thus, a strategy to decrease exposure, e.g., to dust, seems a feasible way to reduce the risk. KEYWORDS: cancer; construction industry INTRODUCTION The workplace for construction workers is often temporary, and employees often work in small groups far from planning departments and production managers. Working conditions may be different compared to traditional industrial workers. The exposure to physical and chemical agents in the construction trades will depend on working techniques and handling and will often be difficult to predict and estimate. In some countries like Sweden, the construction Address for correspondence: Bengt Järvholm, M.D., Ph.D., Professor of Occupational and Environmental Medicine, Department of Public Health and Clinical Medicine, Umeå University, NUS, SE-901 85 Umeå, Sweden. Voice: +46-90-785-2241; fax: +46-90-785-2456. e-mail: bengt.jarvholm@envmed.umu.se Ann. N.Y. Acad. Sci. 1076: 421 428 (2006). C 2006 New York Academy of Sciences. doi: 10.1196/annals.1371.055 421

422 ANNALS NEW YORK ACADEMY OF SCIENCES trades are made up of skilled workers who often have years of training. In other countries, several construction trades are consider unskilled and require brief or no training in the safe handling of dangerous agents. Exposure to carcinogens may vary between jobs, between countries, and over time in the construction trades. This makes estimation of risk difficult. To study the total risk of cancer in construction workers is of very limited value due to the variable exposure. Studies of Japanese and German construction workers found risk of death from cancer similar to that of the general population (SMR = 0.98, 95% CI = 0.90 1.07 and SMR = 0.89, 95% CI = 0.79 1.00). 1,2 This article will show that some construction workers have a considerable and preventable risk of cancer. LUNG CANCER Studies of construction workers usually show a moderately increased risk of lung cancer (relative risk [RR] of about 1.1 1.3) and highly increased risk in some trades. 2 4 The latter are typically studies of insulation workers. 5 7 It is understandable that the risk varies as the exposure to possible carcinogens may vary between jobs, within jobs, and over time just as variable exposure to asbestos may partly explain the variable risk of lung cancer over time. Some activities of exposure to some established or probable lung carcinogens are listed in TABLE 1. Exposure to silica is common for some workers in the construction industry, e.g., rock workers. No study found convincingly that such exposure causes an increased risk of any type of cancer among construction workers, but this is hard to investigate due to the variable exposure. Exposure to asphalt fumes has been discussed as a cause of lung cancer. Asphalt contains bitumen, which is a high boiling mineral oil fraction with a complex chemical composition including polycyclic aromatic hydrocarbons TABLE 1. Examples of exposure to lung carcinogens occurring in the construction trade and classification according to IARC Classification according to IARC Carcinogen (ref) Exposure Asbestos I Insulation Silica I Tunnel work, drilling in rocks Polycyclic aromatic I (varies according to Coal tar used by roofers hydrocarbons substance/mixture) Hexavalent chromium I Welding in stainless steel Diesel exhausts IIa Heavy equipment operations, truck driving especially in tunnels, etc. Radon I Tunnel work

JÄRVHOLM: CARCINOGENESIS: CONSTRUCTION INDUSTRY 423 (PAH). Previously, coal tar was a common additive to asphalt; today this is rare. A recent study of asphalt workers from eight countries showed variable risks between countries, but a slight significantly increased risk overall (SMR = 1.17, 95% CI = 1.04 1.30). 8 A possible confounding influence from other factors could not be ruled out, and a case reference study in the cohort is ongoing in some countries. Smoking habits were known among the Swedish bitumen workers, and these workers were found to have a similar risk of lung cancer as the general population (SMR = 0.88, 95% CI = 0.57 1.29). 9 However, some asphalt workers handle mastic asphalt with sometimes a content of coal tar and may also work indoors using this material. Thus, within the group of asphalt workers there may be large differences in exposure to probable carcinogens, such as PAH. Earlier studies from Denmark have indicated an increased risk of lung cancer among mastic asphalt workers. 10 Tunnel work could mean exposure to high concentrations of radon and diesel exhausts. Because radon has caused lung cancer in miners, it is reasonable to regard such exposure as a risk for construction workers in similar environments. Exposure to diesel exhaust is also difficult to estimate, and the risk of lung cancer among diesel-exposed construction workers has varied from no increased to a slightly increased risk. 3 A recent study indicated a possible association between exposure to diesel exhaust and multiple myeloma in construction workers. 11 MESOTHELIOMA Asbestos is known to cause mesothelioma of the pleura or peritoneum. It has been estimated that 80% of all male cases of mesothelioma can be attributed to occupational exposure to asbestos. 12 Asbestos has long been used in the construction industry, e.g., by insulation workers applying asbestos on pipes and spraying it on walls, steel structures, etc. Plumbers who worked on pipes insulated by asbestos were also exposed. In a Swedish cohort of construction workers who participated in health examinations through Bygghälsan between 1971 and 1993, the occurrence of pleural mesothelioma has been investigated through a linkage with the Swedish Cancer Register. Between 1975 and 1984, there were in total 38 cases of which 14 (37%) occurred among insulation workers and plumbers. The Bygghälsan cohort is estimated to include more than 80% of all construction workers in Sweden during 1971 1993. Between 1998 and 2002, the construction workers in this cohort constituted about 20 25% of all male cases of pleural mesothelioma (FIG. 1). Because not all construction workers were included in the cohort, it is reasonable to estimate that 25 40% of all male cases of pleural mesothelioma had a considerable part of their exposure to asbestos in the construction trades and that this exposure caused their disease. Pleural mesothelioma caused by occupational asbestos exposure is certainly preventable.

424 ANNALS NEW YORK ACADEMY OF SCIENCES FIGURE 1. Incident cases of pleural mesothelioma among men in Sweden and in a cohort of Swedish construction workers (Bygghälsokohorten) between 1971 and 2002. The occupational titles of the men in the construction worker cohort that had pleural mesothelioma diagnosed between 1998 and 2002 are described in FIGURE 2. About 20% of the cases with pleural mesothelioma were plumbers and insulation workers, while occupational groups with similar numbers of cases were concrete workers, carpenters, and electricians. The latter groups were probably indirectly exposed to asbestos, i.e., they did not work with asbestos themselves, but worked in areas where other occupational groups handled asbestos. OTHER TUMORS Construction workers are a large occupational group in many countries. Studies of associations between occupational titles and cancer based on death certificates or cancer registers often include construction workers. Such linkages have sometimes shown increased risk and sometimes not. A review of all such studies would be very extensive and is beyond the scope of this paper. An increased risk of lip cancer has been found among workers in the construction trades. A possible agent is exposure to UV-radiation possibly in combination with dust. 13 A few recent studies have linked cancer in the upper respiratory or digestive tract to exposure in the construction trades, 14 16 but it is still uncertain if the link is causal. Cement dust or other inorganic dusts have also been suggested as causative agents.

JÄRVHOLM: CARCINOGENESIS: CONSTRUCTION INDUSTRY 425 FUTURE EXPOSURE TO CARCINOGENS Asbestos has been recognized as carcinogen in most western industrialized countries. Many such countries have heavy restrictions or prohibition of asbestos use. However, some countries have not attempted or have been unable to control exposure to asbestos in the construction industry, and it is reasonable to believe that in the future we will have reports of high risk for asbestosrelated cancers among construction workers from such countries. Because of the temporary work sites, low control from supervisors, etc., it is very difficult to have very low exposure to asbestos if it is widely used. Indirect or secondary exposure is hard to avoid because workers with secondary exposure may not be aware of such exposure. The Swedish experience (FIG. 2) shows that secondary exposure could be the cause of a majority of the mesothelioma cases among construction workers. Indeed, 25 40% of all cases of mesothelioma in a country may be attributable to indirect exposures. Even in countries where exposure to asbestos has been brought to a minimum, there are still carcinogens around that will be difficult to eliminate during the next decades (TABLE 1). Apart from those in TABLE 1, there are FIGURE 2. Occurrence of pleural mesothelioma (n = 108) between 1998 and 2002 according to occupational title among men in the Swedish construction worker cohort.

426 ANNALS NEW YORK ACADEMY OF SCIENCES other suspected or possible carcinogens including solvents, formaldehyde, hard wood, etc. Some animal studies and studies of lung cancer risk in the general environment indicate that biodurable particles may constitute a risk for cancer. 17,18 Because the application of epidemiology in the construction trades is difficult, mainly due to the difficulties in estimating exposure in this industry, there is less of a science base to build on to prevent or even estimate risk. This does not mean that such studies are not needed or cannot be performed. Well-designed surveillance or cohort studies can measure both overall risk and sometimes detect new risks, especially if the exposure is common. But such studies are expensive and require more resources than most countries are willing to provide, and it is not realistic to expect that industry itself will find ways to finance research. Therefore, government agencies have a more significant duty to protect construction workers than might be the case in some other industries, such as manufacturing. A strategy to eliminate all possible carcinogenic substances seems less feasible, at least in the next decades, because the political will to do so does not exist. Even with well-established carcinogens, such as asbestos and benzene, progress has been slow in most countries. Therefore, the most practical alternative approach is to decrease exposure in general, which will mean a lower risk. How low the risk will be will depend on the exposure, but even this concept is a hard sell even though it is well established that a low exposure environment generally means a clean work environment as well, which in turn often means a more productive environment. During the last decades, it has been obvious that there is a large interindividual and intraindividual variability of exposure in many branches and jobs. 19 High variability usually means that it is difficult to predict the concentration just by experience or by a short visit at the workplace. A recent study of the construction industry in the Toronto region showed very high variability and very high exposures in some tasks. 20 In 73 measurements of total dust, concentrations varied from non-detectable to 848 mg/m 3. The highest levels (325, 346, and 848 mg/m 3 ) were recorded during rock crushing and fireproof mixing. Measurements with a direct-reading instrument showed also very variable concentrations of dust. The highest level (61 mg/m 3, respirable dust) was for a laborer. The concentration of elemental carbon, a marker of diesel exhausts, varied from 4.9 to 146 g/m 3 in laborers. The latter concentration is comparable to exposure in mines where diesel equipment is used in confined spaces. Exposure to Silica was low, and only 4 of 40 samples analyzed for silica showed detectable levels (all four below 0.05 mg/m 3, the current MAC in Sweden). However, a U.S. study found high levels of Silica, often exceeding the MAC in the construction industry. 21 Measurements in different German industries have shown variable and high concentrations of dust in the construction trades (GESTIS stoffdatenbank,

JÄRVHOLM: CARCINOGENESIS: CONSTRUCTION INDUSTRY 427 http://www.hvbg.de/d/bia/fac/stoffdb/ Oct 6, 2005). The German findings indicate that the construction trade is the industry with the highest exposure to dust. Thus, workers in the construction trades have a variable and sometimes very high exposure to dust of variable composition. From data from a limited number of countries, it seems that the exposure is higher than in most other industrial branches. FUTURE RISKS The construction workers during the next decades will certainly be exposed to carcinogens. The level of the exposure will depend on job task and country and will vary over time. To estimate the risk is difficult. However, good working practice, with low levels of exposure through skillful technical and organizational activities, will keep the risk low. Highly carcinogenic substances should naturally not be introduced and should be eliminated, but it is unlikely that elimination of those carcinogens will occur in some construction trades (TABLE 1). Currently, the levels of total dust are very high in most construction work environments. The knowledge of how to decrease such exposure should be obvious for most trained occupational hygienists. By focusing on the reduction of overall dust concentrations, significant gains will also be made in reducing exposure to carcinogens. REFERENCES 1. SUN, J. et al. 2002. Mortality among Japanese construction workers in Mie Prefecture. Occup. Environ. Med. 59: 512 516. 2. ARNDT,V.et al. 2004. All-cause and cause specific mortality in a cohort of 20 000 construction workers; results from a 10 year follow up. Occup. Environ. Med. 61: 419 425. 3. JÄRVHOLM, B.& D. SILVERMAN. 2003. Lung cancer in heavy equipment operators and truck drivers with diesel exhaust exposure in the construction industry. Occup. Environ. Med. 60: 516 520. 4. DEMENT, J.et al. 2003. Cancer incidence among union carpenters in New Jersey. J. Occup. Environ. Med. 45: 1059 1067. 5. JARVHOLM, B.& A. SANDÉN. 1998. Lung cancer and mesothelioma in the pleura and peritoneum among Swedish insulation workers. Occup. Environ. Med. 55: 766 770. 6. HENDERSON, D.W. et al. 2004. After Helsinki: a multidisciplinary review of the relationship between asbestos exposure and lung cancer, with emphasis on studies published during 1997-2004. Pathology 36: 517 550. 7. ULVESTAD, B. et al. 2004. Cancer incidence among members of the Norwegian trade union of insulation workers. J. Occup. Environ. Med. 46: 84 89. 8. BOFETTA, P. et al. 2003. Cancer mortality among European asphalt workers: an international epidemiological study: exposure to bitumen fumes and other agents. Am. J. Ind. Med. 43: 28 39.

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