Lung cancer near an industrial site in Lithuania with major emissions of airway irritants

Residents' Self-Reported Health Effects and Annoyance in Relation to Air Pollution Exposure in an Industrial Area in Eastern-Estonia

Eastern Estonia has large oil shale mines and industrial facilities mainly focused on electricity generation from oil shale and shale oil extraction, which produce high air pollution emissions. The "Study of the health impact of the oil shale sector-SOHOS" was aimed at identifying the impacts on residents' health and annoyance due to the industrial processing. First, a population-wide survey about health effects and annoyance was carried out. Second, the total and oil shale sectors' emitted concentrations of benzene, phenol, and PM2.5 were modelled. Third, the differences between groups were tested and relationships between health effects and environmental pollution studied using multiple regression analysis. Compared to the control groups from non-industrial areas in Tartu or Lääne-Viru, residents of Ida-Viru more frequently (p < 0.05) reported wheezing, chest tightness, shortness of breath, asthma attacks, a long-term cough, hypertension, heart diseases, myocardial infarction, stroke, and diabetes. All health effects except asthma were reported more frequently among non-Estonians. People living in regions with higher levels of PM2.5, had significantly higher odds (p < 0.05) of experiencing chest tightness (OR = 1.13, 95% CI 1.02-1.26), shortness of breath (1.16, 1.03-1.31) or an asthma attack (1.22, 1.04-1.42) during the previous year. People living in regions with higher levels of benzene had higher odds of experiencing myocardial infarction (1.98, 1.11-3.53) and with higher levels of phenol chest tightness (1.44, 1.03-2.00), long-term cough (1.48, 1.06-2.07) and myocardial infarction (2.17, 1.23-3.83). The prevalence of adverse health effects was also higher among those who had been working in the oil shale sector. Next to direct health effects, up to a quarter of the residents of Ida-Viru County were highly annoyed about air pollution. Perceived health risk from air pollution increased the odds of being annoyed. Annoyed people in Ida-Viru had significantly higher odds of experiencing respiratory symptoms during the last 12 months, e.g., wheezing (2.30, 1.31-4.04), chest tightness (2.88, 1.91-4.33 or attack of coughing (1.99, 1.34-2.95).

Using the Negative Exponential Model to Describe Changes in Risk of Smoking-Related Diseases following Changes in Exposure to Tobacco

Recently published analyses for four smoking-related diseases show that the declining excess relative risk by time quit is well fitted by the negative exponential model. These analyses estimated the half-life of this excess, that is, the time after quitting when the excess relative risk reaches half that for continuing smokers. We describe extensions of the simple model. One quantifies the decline following an exposure reduction. We show that this extension satisfactorily predicts results from studies investigating the effect of reducing cigarette consumption. It may also be relevant to exposure reductions following product-switching. Another extension predicts changes in excess relative risk occurring following multiple exposure changes over time. Suitable published epidemiological data are unavailable to test this, and we recommend its validity to be investigated using large studies with data recorded on smoking habits at multiple time points in life. The basic formulae described assume that the excess relative risk for a continuing smoker is linearly related to exposure and that the half-life is invariant of age. We describe model adaptations to allow for nonlinear dose-response and for age-dependence of the half-life. The negative exponential model, though relatively simple, appears to have many potential uses in epidemiological research for summarizing variations in risk with exposure changes.

A review of the epidemiological methods used to investigate the health impacts of air pollution around major industrial areas

We performed a literature review to investigate how epidemiological studies have been used to assess the health consequences of living in the vicinity of industries. 77 papers on the chronic effects of air pollution around major industrial areas were reviewed. Major health themes were cancers (27 studies), morbidity (25 studies), mortality (7 studies), and birth outcome (7 studies). Only 3 studies investigated mental health. While studies were available from many different countries, a majority of papers came from the United Kingdom, Italy, and Spain. Several studies were motivated by concerns from the population or by previous observations of an overincidence of cases. Geographical ecological designs were largely used for studying cancer and mortality, including statistical designs to quantify a relationship between health indicators and exposure. Morbidity was frequently investigated through cross-sectional surveys on the respiratory health of children. Few multicenter studies were performed. In a majority of papers, exposed areas were defined based on the distance to the industry and were located from <2 km to >20 km from the plants. Improving the exposure assessment would be an asset to future studies. Criteria to include industries in multicenter studies should be defined.

Association between cancer risk and drug-metabolizing enzyme gene (CYP2A6, CYP2A13, CYP4B1, SULT1A1, GSTM1, and GSTT1) polymorphisms in cases of lung cancer in Japan

Genetic polymorphisms of enzymes involved in the metabolism of carcinogens are suggested to modify an individual's susceptibility to lung cancer. The purpose of this study was to investigate the relationship between lung cancer cases in Japan and variant alleles of cytochrome P450 (CYP) 2A6 (CYP2A6*4), CYP2A13 (CYP2A13*1-*10), CYP4B1 (CYP4B1*1-*7), sulfotransferase 1A1 (SULT1A1*2), glutathione S-transferase M1 (GSTM1 null), and glutathione S-transferase T1 (GSTT1 null). We investigated the distribution of these polymorphisms in 192 lung cancer patients and in 203 age- and sex-matched cancer-free controls. The polymorphisms were analyzed using various techniques including allele-specific PCR, hybridization probe assay, multiplex PCR, denaturing high-performance liquid chromatography (DHPLC), and direct sequencing. We also investigated allele and genotype frequencies and their association with lung cancer risk, demographic factors, and smoking status. The prevalence of the CYP2A6*4/*4 genotype in lung cancer cases was 3.6%, compared with 9.4% in the controls (adjusted OR = 0.36, 95% CI = 0.15-0.88, P = 0.025). In contrast, there was no association between the known CYP2A13, CYP4B1, SULT1A1, GSTM1, and GSTT1 polymorphisms and lung cancer. These data indicate that CYP2A6 deletions may be associated with lung cancer in the Japanese population studied.

Traffic air pollution and lung cancer in females in Taiwan: petrol station density as an indicator of disease development

To investigate the relationship between traffic air pollution exposure and development of lung cancer in females, studies were conducted using a matched cancer case-control model into deaths that occurred in Taiwan from 1997 through 2006. Data on all eligible lung cancer deaths in females were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. The control group consisted of women who died from causes other than neoplasms or diseases that were associated with respiratory problems. The controls were pair matched to the cancer cases by year of birth and year of death. Each matched control was selected randomly from the set of possible controls for each case. Data on the number of petrol stations in study municipalities were collected from the two major petroleum supply companies, Chinese Petroleum Corporation (CPC) and Formosa Petrochemical Corporation (FPCC). The petrol station density (per square kilometer; PSD) for study municipalities was used as an indicator of a subject's exposure to benzene and other hydrocarbons present in ambient evaporative losses of petrol or to air emissions from motor vehicles. The subjects were divided into tertiles according to PSD in their residential municipality. The results showed that there was a significant exposure-response relationship between PSD and risk of lung cancer in females after controlling for possible confounders. The findings of this study warrant further investigation of the role of traffic air pollution exposure in the etiology of lung cancer.

Ambient exposure to criteria air pollutants and female lung cancer in Taiwan

To investigate the relationship between air pollution and female lung cancer, the authors conducted a matched case-control study using female deaths that occurred in Taiwan from 1995 through 2005. Data on all eligible female lung cancer deaths were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. The control group consisted of women who died from causes other than cancer or diseases associated with respiratory problems. The controls were pair-matched to the cases by sex, year of birth, and year of death. Each matched control was selected randomly from the set of possible controls for each case. Classification of exposure to municipality air pollution was based on the measured levels of nitrogen dioxide and carbon monoxide. The results of the present study show that there is a significant positive association between the levels of air pollution and female lung cancer mortality. The adjusted odds ratios (95% confidence interval) were 1.24 (1.03-1.50) for the group with medium air pollution level and 1.46 (1.18-1.81) for the group with high air pollution level when compared to the group with the low air pollution level. Trend analyses showed statistically significant trend in risk of female lung cancer with increasing air pollution level. The findings of this study warrant further investigation of the role of air pollutants in the etiology of lung cancer.

Outdoor air pollution and female lung cancer in Taiwan

To investigate the relationship between air pollution and female lung cancer, the authors conducted a matched case-control study using female deaths that occurred in Taiwan from 1994 through 2003. Data on all eligible female lung cancer deaths were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. The control group consisted of women who died from causes other than cancer or diseases associated with respiratory problems. The controls were pair matched to the cases by sex, year of birth, and year of death. Each matched control was selected randomly from the set of possible controls for each case. A municipality-based aggregate index of long-term exposure to air pollution was created by dividing the annual average of the measured values for each pollutant by the National Ambient Air Quality Standard for that pollutant. The ratios for each pollutant were scaled to a 100-point scale and then averaged together to generate an index value representing the net burden of these pollutants, with each weighted equally. The subjects were divided into tertiles according to the levels of the index just described. Women who lived in the group of municipalities with highest levels of air pollution exposure index were at a statistically significant increased lung cancer risk compared to the group living in municipalities with the lowest air pollution exposure index after controlling for possible confounders (OR = 1.28, 95% CI = 1.02-1.61). The findings of this study warrant further investigation of the role of air pollutants in the etiology of lung cancer.

Status of occupational cancer in Lithuania

Because industrialization in Lithuania started only about 50 years ago, occupational cancer is only now becoming an important issue. This article describes the situation of occupational cancer in Lithuania: research, exposures to carcinogens, regulation, and legal practice. Epidemiologic studies of work-related cancers have shown increased risks among cement, textile, and asbestos-cement workers. In 1997, 28% of employed workers in Lithuania were exposed to carcinogens. A legislation system regulating exposures to carcinogens, harmonized with European Directives, has recently been created. In 1995-2003, there were 5,652 new cases of occupational diseases. However, occupational cancers are seriously underdiagnosed--only one case of cancer was diagnosed as occupational. Establishment of a system that would enable diagnosis, certification, and compensation of cases of occupational neoplasms is essential in Lithuania.

Epidemiology of environmental and occupational cancer

Environmental carcinogens, in a strict sense, include outdoor and indoor air pollutants, as well as soil and drinking water contaminants. An increased risk of mesothelioma has consistently been detected among individuals experiencing residential exposure to asbestos, while results for lung cancer are less consistent. Several good-quality studies have investigated lung cancer risk from outdoor air pollution based on measurement of specific agents. Their results tend to show an increased risk in the categories at highest exposure, with relative risks in the range 1.5. A causal association has been established between exposure to environmental tobacco smoke and lung cancer, with a relative risk in the order of 1.2. Radon is another carcinogen present in indoor air, with a relative risk in the order of 1.06 for exposure at 100 Bq/m3. In several Asian populations, an increased risk of lung cancer results among women from indoor pollution from cooking and heating. There is strong evidence of an increased risk of bladder, skin and lung cancers following consumption of water with high arsenic contamination; results for other drinking water contaminants, including chlorination by-products, are inconclusive. A total of 29 occupational agents are established human carcinogens, and another 30 agents are suspected carcinogens. In addition, at least 12 exposure circumstances entail exposure to carcinogens. Exposure is still widespread for many important occupational carcinogens, such as asbestos, coal tar, arsenic and silica, in particular in developing countries. Although estimates of the global burden of occupational and environmental cancer result in figures in the order of 2% and less than 1%, respectively, these cancers concentrate in subgroups of the population; furthermore, exposure is involuntary and can, to a large extent, be avoided.

Air pollution and lung cancer mortality in the vicinity of a nonferrous metal smelter in Sweden

To evaluate the importance of exposure to ambient air pollution for lung cancer risk, we conducted a case-control study in the vicinity of a nonferrous metal smelter. The smelter started operations in 1930 and had very high emissions during the early decades, particularly of arsenic and SO(2). Among subjects deceased 1961-1990 in the municipality where the smelter is located and who had not worked at the smelter, 209 male and 107 female lung cancer cases were identified and matched by sex and year of birth to 518 and 209 controls, respectively. Information on smoking habits, occupations and residences was collected by questionnaire to next-of-kin and from registry data. Living close to the smelter was associated with a relative risk (RR) for lung cancer of 1.38 [95% confidence interval (CI) 0.89-2.14] among men, adjusted for smoking and occupational exposures. No clear difference in risk was detected for men deceased 1961-1979 compared to men deceased 1980-1990 (RR point estimates 1.42 and 1.29, respectively). There appeared to be an increased risk especially for men exposed in the beginning of the operations (RR = 1.51, 95% CI 0.90-2.54), in particular combined with exposure duration shorter than 20 years (RR = 2.52, 95% CI 0.89-7.11). For women, however, no overall increased risk for lung cancer was observed. Although not significant, our findings thus indicated an increased risk of lung cancer among men living close to the nonferrous smelter. This increase appeared to concern primarily men exposed during the early years of operations, when emissions were very high.

Contribution of environmental factors to cancer risk

Environmental carcinogens, in a strict sense, include outdoor and indoor air pollutants, as well as soil and drinking water contaminants. An increased risk of mesothelioma has consistently been detected among individuals experiencing residential exposure to asbestos, whereas results for lung cancer are less consistent. At least 14 good-quality studies have investigated lung cancer risk from outdoor air pollution based on measurement of specific agents. Their results tend to show an increased risk in the categories at highest exposure, with relative risks in the range 1.5-2.0, which is not attributable to confounders. Results for other cancers are sparse. A causal association has been established between exposure to environmental tobacco smoke and lung cancer, with a relative risk in the order of 1.2. Radon is another carcinogen present in indoor air which may be responsible for 1% of all lung cancers. In several Asian populations, an increased risk of lung cancer is present in women from indoor pollution from cooking and heating. There is strong evidence of an increased risk of bladder, skin and lung cancers following consumption of water with high arsenic contamination; results for other drinking water contaminants, including chlorination by-products, are inconclusive. A precise quantification of the burden of human cancer attributable to environmental exposure is problematic. However, despite the relatively small relative risks of cancer following exposure to environmental carcinogens, the number of cases that might be caused, assuming a causal relationship, is relatively large, as a result of the high prevalence of exposure.