Reactive chemicals and cancer

Industrial pollution and mortality from digestive cancers at the small area level in a Spanish industrialized province

The province of Cadiz, Spain, is a highly industrialized area with numerous registered industrial plants, which has led to major concern regarding the possible influence of these facilities on the high rate of cancer-related mortality observed. Our objective was to evaluate the association between digestive cancer mortality and proximity to industrial installations in the province of Cadiz over the period 1992-2014 and to analyse this risk according to different categories of carcinogenic substances. An ecological study at the census tract level was carried out. Mortality due to digestive cancer (involving the oral cavity, pharynx, oesophagus, stomach, liver, pancreas, gallbladder, colon and rectum) was analysed. Using the spatial Besag, York and Mollié (BYM) approach, we assessed the relative risk of dying from these cancers for people living between 500 m and 5 km from industrial installations. The models were adjusted to account for socioeconomic deprivation. We detected a significant, excess risk of dying due to cancer in the following organs (expressed as relative risk with 95% confidence intervals): colon/rectum (1.13; 1.04-1.22 at 4 km), stomach (1.13; 1.00-1.29 at 2 km), liver (1.28; 1.02-1.61 at 1 km), pancreas (1.19; 1.03-1.39 at 2 km), oral and pharyngeal (1.40; 1.08-1.82 at 1 km), oesophagus (2.05; 1.18-3.56 at 500 m) and gallbladder (2.80; 1.14-6.89 at 500 m) for men; and from colorectal (1.21; 1.00-1.46 at 1 km), stomach (1.15; 1.01-1.31 at 4 km) and liver (1.58; 1.20- 2.07 at 1 km) cancers for women. The results support the hypothesis of an association between several digestive cancers and proximity to polluting industrial plants.

A review on recent developments of anion exchange membranes for fuel cells and redox flow batteries

This review covers recent advancements and future perspectives of AEMs for energy conversion and storage systems such as fuel cells and redox flow batteries.

Extent of Nucleophilic Participation in the Solvolyses of an Aryl Chloromethyl Ether, α, p-Dichloroanisole

The specific rates of solvolysis of α, p-dichloroanisole (chloromethyl p-chlorophenyl ether, 1) have been measured conductimetrically in a variety of hydroxylic solvents. In three typical solvents, at 25.0 °C, the rate is 20–45 times greater than for the corresponding sulfide. In a comparison with the solvolysis of a substrate with an alkyl group replacing the aryl group, chloromethyl ethyl ether (2), at −10.0 °C in four typical solvents, 1 reacted considerably more slowly than 2, by a little over four orders of magnitude. An extended Grunwald–Winstein equation treatment of the specific rates of solvolyses in 24 solvents at 25.0 °C leads to an l value of 0.68 ± 0.04 and an m value of 0.59 ± 0.03 ( l/ m = 1.15). Appreciable nucleophilic assistance in the progress to the transition state is indicated and either nucleophilic solvation to an ionisation process or a loose SN2 transition state with extensive bond-breaking accompanied by a smaller degree of bond-making lead to an appropriate transition state.

Extent of Nucleophilic Participation in the Solvolyses of Alkyl Chloromethyl Ethers and Sulfides

The specific rates of solvolysis have been determined for chloromethyl ethyl ether (3) and chloromethyl octyl ether (4) at −10.0 °C and for chloromethyl methyl sulfide (5) at 25.0 °C in a variety of pure and binary solvents. These values were used for a correlation analysis treatment using the extended Grunwald–Winstein equation incorporating literature values for solvent nucleophilicity ( NT) and solvent ionising power ( YCl). Appreciable values were found for the sensitivities towards changes in both NT and YCl values. Using a literature specific rate of hydrolysis at 25.0 °C for fluoromethyl methyl ether (2), the required value for chloromethyl methyl ether (1) was obtained from use of NT and YCl values and the sensitivities for 3 to changes in their values, to adjust an experimental specific rate value for 1 in 100% ethanol to the corresponding value in 100% water. In this way, an estimated kCl/ kF of 1.2 × 105 was obtained, essentially identical to values for the solvolyses of tert-butyl halides. A unimolecular mechanism for the solvolyses, with appreciable nucleophilic solvation of the developing carbocation, is proposed. Electronic supplementary information provides, for several solvents, specific rates of solvolysis for 3, 4, and 5 at additional temperatures and the calculated activation parameters.

Investigation of occupational and environmental causes of respiratory cancers (ICARE): a multicenter, population-based case-control study in France

BACKGROUND

Occupational causes of respiratory cancers need to be further investigated: the role of occupational exposures in the aetiology of head and neck cancers remains largely unknown, and there are still substantial uncertainties for a number of suspected lung carcinogens. The main objective of the study is to examine occupational risk factors for lung and head and neck cancers.

METHODS/DESIGN

ICARE is a multi-center, population-based case-control study, which included a group of 2926 lung cancer cases, a group of 2415 head and neck cancer cases, and a common control group of 3555 subjects. Incident cases were identified in collaboration with cancer registries, in 10 geographical areas. The control group was a random sample of the population of these areas, with a distribution by sex and age comparable to that of the cases, and a distribution by socioeconomic status comparable to that of the population. Subjects were interviewed face to face, using a standardized questionnaire collecting particularly information on tobacco and alcohol consumption, residential history and a detailed description of occupational history. Biological samples were also collected from study subjects. The main occupational exposures of interest are asbestos, man-made mineral fibers, formaldehyde, polycyclic aromatic hydrocarbons, chromium and nickel compounds, arsenic, wood dust, textile dust, solvents, strong acids, cutting fluids, silica, diesel fumes, welding fumes. The complete list of exposures of interest includes more than 60 substances. Occupational exposure assessment will use several complementary methods: case-by-case evaluation of exposure by experts; development and use of algorithms to assess exposure from the questionnaires; application of job-exposure matrices.

DISCUSSION

The large number of subjects should allow to uncover exposures associated with moderate increase in risks, and to evaluate risks associated with infrequent or widely dispersed exposures. It will be possible to study joint effects of exposure to different occupational risk factors, to examine the interactions between occupational exposures, tobacco smoking, alcohol drinking, and genetic risk factors, and to estimate the proportion of respiratory cancers attributable to occupational exposures in France. In addition, information on many non-occupational risk factors is available, and the study will provide an excellent framework for numerous studies in various fields.

Economic burden of occupational injury and illness in the United States

CONTEXT

The allocation of scarce health care resources requires a knowledge of disease costs. Whereas many studies of a variety of diseases are available, few focus on job-related injuries and illnesses. This article provides estimates of the national costs of occupational injury and illness among civilians in the United States for 2007.

METHODS

This study provides estimates of both the incidence of fatal and nonfatal injuries and nonfatal illnesses and the prevalence of fatal diseases as well as both medical and indirect (productivity) costs. To generate the estimates, I combined primary and secondary data sources with parameters from the literature and model assumptions. My primary sources were injury, disease, employment, and inflation data from the U.S. Bureau of Labor Statistics (BLS) and the Centers for Disease Control and Prevention (CDC) as well as costs data from the National Council on Compensation Insurance and the Healthcare Cost and Utilization Project. My secondary sources were the National Academy of Social Insurance, literature estimates of Attributable Fractions (AF) of diseases with occupational components, and national estimates for all health care costs. Critical model assumptions were applied to the underreporting of injuries, wage-replacement rates, and AFs. Total costs were calculated by multiplying the number of cases by the average cost per case. A sensitivity analysis tested for the effects of the most consequential assumptions. Numerous improvements over earlier studies included reliance on BLS data for government workers and ten specific cancer sites rather than only one broad cancer category.

FINDINGS

The number of fatal and nonfatal injuries in 2007 was estimated to be more than 5,600 and almost 8,559,000, respectively, at a cost of $6 billion and $186 billion. The number of fatal and nonfatal illnesses was estimated at more than 53,000 and nearly 427,000, respectively, with cost estimates of $46 billion and $12 billion. For injuries and diseases combined, medical cost estimates were $67 billion (27% of the total), and indirect costs were almost $183 billion (73%). Injuries comprised 77 percent of the total, and diseases accounted for 23 percent. The total estimated costs were approximately $250 billion, compared with the inflation-adjusted cost of $217 billion for 1992.

CONCLUSIONS

The medical and indirect costs of occupational injuries and illnesses are sizable, at least as large as the cost of cancer. Workers' compensation covers less than 25 percent of these costs, so all members of society share the burden. The contributions of job-related injuries and illnesses to the overall cost of medical care and ill health are greater than generally assumed.

Peritoneal sarcomatosis associated with telemetry implants in Sprague Dawley CD rats: a review of eight cases

Surgical implantation of radiotelemetric transmitters is a current practice to collect a variety of physiological parameters in unrestrained laboratory animals, and in rodents in particular. In this study, the incidence of peritoneal sarcomatosis arising secondary to surgically implanted telemetry devices (< 15% of implanted Sprague Dawley rats) is considered to represent a significant issue for both animal welfare and data validity in affected animals. Macroscopically, the telemetry-associated fibrosarcomas spread along the visceral and parietal peritoneum and mesentery surrounding abdominal organs. The histologic morphology of these sarcomas was typically an undifferentiated sarcoma, although well-differentiated fibrosarcomas and telangiectatic and pleomorphic variants were noted. Using special stains such as Masson's Trichrome demonstrated a collagenous extracellular matrix in 50% of these rats, which is consistent with a fibroblastic origin. Immunohistochemical studies clearly delineated the mesenchymal components of the sarcomas (fibroblasts and smooth muscle cells); one case, however, was diagnosed as an osteosarcoma.

Leukemia-related mortality in towns lying in the vicinity of metal production and processing installations

BACKGROUND

Releases to the environment of toxic substances stemming from industrial metal production and processing installations can pose a health problem to populations in their vicinity.

OBJECTIVES

To investigate whether there might be excess leukemia-related mortality in populations residing in towns in the vicinity of Spanish metal industries included in the European Pollutant Emission Register.

METHODS

Ecologic study designed to examine mortality due to leukemia at a municipal level, during the period 1994-2003. Population exposure to pollution was estimated on the basis of distance from town of residence to pollution source. Using Poisson regression models, we analyzed: risk of dying from leukemia in a 5-kilometer zone around installations which had become operational prior to 1990; effect of pollution discharge route and type of industrial activity; and risk gradient within a 50-kilometer radius of such installations.

RESULTS

Excess mortality (relative risk, 95% confidence interval) was detected in the vicinity of pre-1990 installations (1.07, 1.02-1.13 in men; 1.05, 1.00-1.11 in women), with this being more elevated in the case of installations that released pollution to air versus water. On stratifying by type of industrial activity, statistically significant associations were also observed among women residing in the vicinity of galvanizing installations (1.58, 1.09-2.29) and surface-treatment installations using an electrolytic or chemical process (1.34, 1.10-1.62), which released pollution to air. There was an effect whereby risk increased with proximity to certain installations.

CONCLUSIONS

The results suggest an association between risk of dying due to leukemia and proximity to Spanish metal industries.

Cancer incidence in a petrochemical industry area in Sweden

Emissions from petrochemical industries may contain suspected or established carcinogens. As increased incidence of cancer in residential areas close to petrochemical industries has been reported in the literature, we conducted a study of cancer incidence in Stenungsund, Sweden, where petrochemical industries were established in the mid 1960s. A number of cancer cases in the central parts of Stenungsund were collected from the regional cancer registry for each year between 1974 and 2005. In addition to the total number of cases, the numbers of leukemia, lymphoma, liver cancer, lung cancer, and brain cancer were also collected. Expected numbers for each year were calculated based on age- and sex-specific incidence rates in reference areas. Levels of carcinogenic volatile hydrocarbons (VOC) were estimated from measurements and emission data. A dispersion model was used to classify Stenungsund into a "low" and "high" ethylene level area. Standardized Incidence Ratio (SIR) for all cancer for the entire period was 1.02 (95% CI 0.97-1.08). The occurrence of leukemia, lymphoma, and cancer in the central nervous system was slightly lower than expected for the entire period. SIR for lung cancer was 1.37 (95% CI 1.10-1.69), and SIR for liver cancer was 1.50 (0.82-2.53). VOC levels were low. Taking estimated exposure and demographic factors into account, our assessment is that occurrence of cancer was not affected by industrial emissions in any of the studied sites.

Mortality due to tumours of the digestive system in towns lying in the vicinity of metal production and processing installations

BACKGROUND

Releases to the environment of pollutants from industrial metal production and processing installations can pose a health problem to humans, owing to the toxic substances that such emissions contain.

OBJECTIVES

To investigate whether there might be excess mortality due to tumours of the digestive system among the population residing near Spanish metal production and processing installations included in the European Pollutant Emission Register.

METHODS

Ecological study designed to examine mortality due to malignant tumours of the digestive system (oral cavity and pharynx, oesophagus, stomach, pancreas, liver, gallbladder, and colon-rectum) at the municipal level, over the period 1994-2003. Population exposure to pollution was estimated on the basis of distance from town of residence to the pollution source. Using mixed Poisson regression models, we analysed: risk of dying from cancer in a 5-kilometre zone around installations by year of commencement of operations; effect of pollution discharge route (air or water) and type of industrial activity; and risk gradient within a 50-kilometre radius of such installations.

RESULTS

Excess mortality (relative risk, 95% confidence interval) was detected in the vicinity of pre-1990 installations for colorectal cancer (1.05, 1.02-1.08 in men; 1.04, 1.00-1.07 in women) and liver cancer (1.06, 1.00-1.12 in men), with this risk being concentrated in installations that released pollution to air. On stratifying by type of industrial activity, statistically significant associations were also observed between the remaining tumours and certain metal production and processing activities. There was also a gradient effect in the proximity to a number of installations.

CONCLUSIONS

The results support the existence of an association between risk of dying due to some tumours of the digestive system and residential proximity to the Spanish metal production and processing installations studied.

Management of an incidental liver mass

The increased use of sensitive imaging modalities has led to increased identification of the incidental liver mass (ILM). A combination of careful consideration of patient factors and imaging characteristics of the ILM enables clinicians to recommend a safe and efficient course of action. Using an algorithmic approach, this article includes pertinent clinical factors and the specific radiologic criteria of ILMs and discusses the indications for potential procedures. It is the aim of this article to assist with the development of an individualized strategy for each patient with an ILM.

Mucosal vaccine targeting improves onset of mucosal and systemic immunity to botulinum neurotoxin A

Absence of suitable mucosal adjuvants for humans prompted us to consider alternative vaccine designs for mucosal immunization. Because adenovirus is adept in binding to the respiratory epithelium, we tested the adenovirus 2 fiber protein (Ad2F) as a potential vaccine-targeting molecule to mediate vaccine uptake. The vaccine component (the host cell-binding domain to botulinum toxin (BoNT) serotype A) was genetically fused to Ad2F to enable epithelial binding. The binding domain for BoNT was selected because it lies within the immunodominant H chain as a beta-trefoil (Hcbetatre) structure; we hypothesize that induced neutralizing Abs should be protective. Mice were nasally immunized with the Hcbetatre or Hcbetatre-Ad2F, with or without cholera toxin (CT). Without CT, mice immunized with Hcbetatre produced weak secretory IgA (sIgA) and plasma IgG Ab response. Hcbetatre-Ad2F-immunized mice produced a sIgA response equivalent to mice coimmunized with CT. With CT, Hcbetatre-Ad2F-immunized mice showed a more rapid onset of sIgA and plasma IgG Ab responses that were supported by a mixed Th1/Th2 cells, as opposed to mostly Th2 cells by Hcbetatre-dosed mice. Mice immunized with adjuvanted Hcbetatre-Ad2F or Hcbetatre were protected against lethal BoNT serotype A challenge. Using a mouse neutralization assay, fecal Abs from Hcbetatre-Ad2F or Hcbetatre plus CT-dosed mice could confer protection. Parenteral immunization showed that the inclusion of Ad2F enhances anti-Hcbetatre Ab titers even in the absence of adjuvant. This study shows that the Hcbetatre structure can confer protective immunity and that use of Hcbetatre-Ad2F gives more rapid and sustained mucosal and plasma Ab responses.

Occupational acrylonitrile exposure and lung cancer: a meta-analysis

The present work summarizes the currently available published studies on lung cancer and occupational acrylonitrile exposure. Meta-analytic methods were used to estimate the overall risk. To adjust for the healthy worker effect, rate ratio estimates based on regression analyses and ratios of standard mortality ratios were aggregated. Overall effect estimates were 0.95 (95% CI 0.86 to 1.06) and 1.25 (95% CI 1.10 to 1.43) before and after adjustment for the healthy worker effect, respectively. Therefore, a 25% increase in lung cancer risk attributable to occupational acrylonitrile exposure is suggested. Possible contribution of smoking confounding the increased risk cannot be fully excluded.

Risk of Lung Cancer and Exposure to Industrial Acids, Solvents, and Metals in Leningrad Province, Russia

OBJECTIVE

We sought to investigate the association of occupational exposure to industrial acids, solvents, and metals with lung cancer in Leningrad Province, Russia, where an excess of occupationally related lung cancer was reported recently.

METHODS

We identified 540 pathologically diagnosed lung cancer cases and 582 controls from the 1993-1998 autopsy records of the 88 Leningrad Province hospitals. Lifetime job-specific exposure measurements were available for 12 industrial acids, 15 solvents, and 17 metals.

RESULTS

Exposures were frequent in the study group and mostly occurred after World War II. However, lung cancer risks for industrial acids (odds ratio [OR] = 1.2; 95% confidence interval [CI] = 0.8-1.7), solvents (OR = 0.8; 95% CI = 0.6-1.2), and metals (OR = 0.8; 95% CI = 0.5-1.0) were not increased. Also, no significant excess risk was found for any of the specific agents investigated.

CONCLUSIONS

The excess of occupationally related lung cancer in the Province is not explained by exposure to the agents investigated.

Variation in the risk for liver and gallbladder cancers in socioeconomic and occupational groups in Sweden with etiological implications

OBJECTIVES

To examine the associations between socioeconomic/occupational factors and liver cancer at various anatomic sites (including primary liver, gallbladder and other cancers).

METHODS

We carried out a follow-up study on the economically active Swedish population, based on the Swedish Family-Cancer Database. Standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) were calculated in different social classes and occupations.

RESULTS

For primary liver cancer, farmers were at a decreased risk; increased risks were observed for male sales agents, journalists, seamen, waiters, cooks and female beverage manufacture workers. Similar patterns were observed for gallbladder cancer; workers employed as journalists, sales agents, cooks and stewards, and public safety workers showed increased risk. Only male transport workers showed increased risk of cancers in other parts.

CONCLUSIONS

Occupations with high consumption of alcohol and/or high prevalence of smoking associated with a risk of liver and gallbladder cancers. The present study suggests that the effects of socioeconomic factors on liver cancer of different subsites are similar; alcohol drinking is a risk factor of gallbladder cancer because of the covariation of primary liver and gallbladder cancers in occupational groups.

After the Smoke Clears

Both environmental and occupational exposures are associated with the development of carcinomas of the upper aerodigestive tract, although most squamous cell carcinomas of the upper aerodigestive tract are related to smoking and drinking. This review discusses environmental and occupational risk factors, other than tobacco and alcohol, for carcinoma of the upper aerodigestive tract and the difficulties encountered when attempts are made to study these environmental and occupational exposures. However, this is not an all-inclusive review; rather, it is designed to give the reader an understanding of the topic, to allow for appropriate counseling of patients, and perhaps to advance public health initiatives.

Tissue repair and stem cell renewal in carcinogenesis

Cancer is increasingly being viewed as a stem cell disease, both in its propagation by a minority of cells with stem-cell-like properties and in its possible derivation from normal tissue stem cells. But stem cell activity is tightly controlled, raising the question of how normal regulation might be subverted in carcinogenesis. The long-known association between cancer and chronic tissue injury, and the more recently appreciated roles of Hedgehog and Wnt signalling pathways in tissue regeneration, stem cell renewal and cancer growth together suggest that carcinogenesis proceeds by misappropriating homeostatic mechanisms that govern tissue repair and stem cell self-renewal.

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.

Risk of laryngeal cancer by occupational chemical exposure in Turkey

Laryngeal cancer is the second most common cancer among men in Turkey. In this hospital based case-control study, we evaluated laryngeal cancer risks from occupational chemical exposures. We analyzed 940 laryngeal cancer cases and 1519 controls. Occupational history, tobacco, and alcohol use and demographic information were obtained by a questionnaire. The job and industries were classified by special seven-digit codes. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) based on a developed exposure matrix for chemicals, including diesel exhaust, gasoline exhaust, polycyclic aromatic hydrocarbons (PAHs), formaldehyde, and solvents. An excess of laryngeal cancer occurred with diesel exhaust (OR=1.5, 95% CI=1.3-1.9), gasoline exhaust (OR=1.6, 95% CI=1.3-2.0), and PAHs (OR=1.3, 95% CI=1.1-1.6). There was a dose-response relationship for these substances with supraglottic cancers (P<0.000). The PAH association only occurred among those who also had exposure to diesel exhaust.

Occupational Exposures and Salivary Gland Cancer Mortality Among African American and White Workers in the United States

We conducted a large death certificate-based case-control study to assess occupational risks for salivary gland cancer. African American (168 cases, 672 controls) and white (2237 cases, 8748 controls) cases from 24 states (1984-1989) were matched to controls by age, sex, race, and region. Race- and sex-stratified multiple logistic regression models calculated adjusted odds ratios. The proportion of young cases (<50 years) was greatest among African Americans (20.8% vs. 8.8%). Higher socioeconomic status, ionizing radiation, formaldehyde, solvents, outdoor work, and animal contact were associated with elevated risk among white men. Physical activity reduced mortality risks among men, although significantly only among whites. Odds ratios for formaldehyde, solvents, benzene, and animal contact were 2.0 or greater among African American women, although not statistically significant. These findings suggest occupational and demographic factors needing further investigation.

Dying for work: The magnitude of US mortality from selected causes of death associated with occupation

BACKGROUND

Deaths due to occupational disease and injury place a heavy burden on society in terms of economic costs and human suffering.

METHODS

We estimate the annual deaths due to selected diseases for which an occupational association is reasonably well established and quantifiable, by calculation of attributable fractions (AFs), with full documentation; the deaths due to occupational injury are then added to derive an estimated number of annual deaths due to occupation.

RESULTS

Using 1997 US mortality data, the estimated annual burden of occupational disease mortality resulting from selected respiratory diseases, cancers, cardiovascular disease, chronic renal failure, and hepatitis is 49,000, with a range from 26,000 to 72,000. The Bureau of Labor Statistics estimates there are about 6,200 work-related injury deaths annually. Adding disease and injury data, we estimate that there are a total of 55,200 US deaths annually resulting from occupational disease or injury (range 32,200-78,200).

CONCLUSIONS

Our estimate is in the range reported by previous investigators, although we have restricted ourselves more than others to only those diseases with well-established occupational etiology, biasing our estimates conservatively. The underlying assumptions and data used to generate the estimates are well documented, so our estimates may be updated as new data emerges on occupational risks and exposed populations, providing an advantage over previous studies. We estimate that occupational deaths are the 8th leading cause of death in the US, after diabetes (64,751) but ahead of suicide (30,575), and greater than the annual number of motor vehicle deaths per year (43,501).

Lung cancer and related risk factors: an update of the literature

At the present time, lung cancer is the leading cause of cancer-related death in males. Diagnostic difficulty makes detection complicated and this, in conjunction with the low survival rate, renders the disease a serious health problem. In-depth knowledge of associated risk factors is therefore called for, in order to prevent or at least reduce the appearance of lung cancer and to open new avenues of research. Although the disease has a multicausal aetiology, tobacco accounts for 85-90% of all cases. This paper reviews the current situation, dividing the risk factors, for study purposes, into two groups; intrinsic (non-modifiable) and extrinsic (modifiable).

Occupational risk in health care and research

BACKGROUND

Working in the health care and research sectors has been linked to various hazards.

METHODS

Studies published in the peer-reviewed literature that are pertinent to the exposures or diseases relevant to these fields were reviewed.

RESULTS

The most important exposures include infectious agents, formaldehyde, anesthetic agents, antineoplastic drugs, and ethylene oxide. The best-documented evidence is that of infectious risk primarily among clinical personnel. Monitoring studies of persons occupationally exposed to anesthetics clearly demonstrate behavioral effects, possible risk of reproductive problems, as well as cytogenetic effects of unknown significance. The latter two impairments are also observed among those exposed to antineoplastic drugs and ethylene oxide. Exposure to formaldehyde appears to be associated with nasopharyngeal tumors. Whereas increased risk of cancer of certain sites, particularly the brain and lymphohematopoietic system, is found among research and health care personnel, no specific exposure has been linked to these neoplasms.

CONCLUSIONS

Although some results are inconsistent, continued environmental and biological monitoring will allow better assessment of exposures and of implemented protection measures.

Cancer incidence and magnetic field exposure in industries using resistance welding in Sweden

AIMS

To investigate cancer incidence in workers exposed to high levels of extremely low frequency magnetic fields (ELF-MF).

METHODS

A cohort based on the engineering industry was established. Industries assumed to use resistance welding in production were chosen in order to increase the prevalence of high exposed subjects and to reduce the influence of confounding factors. All men and women employed in these branches during 1985-94 were selected, 537 692 men and 180 529 women. Occupation, based on census information from 1980, 1985, and 1990, was linked to a job exposure matrix on ELF-MF. Four exposure groups were used by stratifying on mean workday ELF-MF exposure, using the lowest exposure group as reference. Cancer incidence was obtained by linkage to the Swedish Cancer Registry.

RESULTS

Men in the very high exposure group showed an increased incidence of tumours of the kidney, pituitary gland, and biliary passages and liver; for these cancer sites an exposure-response relation was indicated. Women in the very high exposure group showed an increased incidence of astrocytoma I-IV, with a clear exposure-response pattern. An association was suggested in the high exposure group only, for cancer of the corpus uteri and multiple myeloma. Decreased risks in the very high exposure group among men were found for cancer of the colon and connective tissue/muscle.

CONCLUSIONS

The results on cancer of the liver, kidney, and pituitary gland among men are in accordance with previous observations. Regarding brain tumours and leukaemia, the outcome for women provided further support of an association. The hypothesis of a biological mechanism involving the endocrine system was partly supported.

Primary liver cancer and occupation in men: a case-control study in a high-incidence area in Northern Italy

The objective of our study was to evaluate the association between occupation and risk of liver cancer. A hospital-based case-control study was carried out during 1997-1999 in the Province of Brescia, a highly industrialized area in Northern Italy with a high incidence of this neoplasm. The cases were 144 male patients with incident liver cancer (96% hepatocellular carcinoma). Controls were 283 male patients, matched to cases on age (+/-5 years), period and hospital of admission. Information on lifetime occupational history and alcohol consumption was obtained via interview. Specific occupational exposures to pesticides, solvents and other suspected hepatocarcinogens were evaluated. A blood sample was collected to detect hepatitis B and C infections. Odds ratios (OR) of occupational exposure and 95% confidence intervals (CI), adjusted for age, residence, education, heavy alcohol intake, hepatitis B surface antigen and hepatitis C virus antibodies positivity were computed. A statistically significant increased OR was observed for employment in repair of motor vehicles (OR 3.7; 95% CI 1.1-12.3; 9 exposed cases, 10 exposed controls). Increased ORs, although not statistically significant, were found for field-crop farm workers, food and beverage processors, blacksmiths and machine-tool operators, electrical fitters, clerical workers, manufacture of industrial machinery and personal and household services. A slightly increased OR was noted in workers exposed to toluene and xylene (OR 1.4; 95% CI 0.7-3.0, 23 cases, 36 controls); the OR was 2.8 (95% CI 1.0-7.6, 11 cases, 12 controls) for 20 or more years of exposure and 2.0 (95% CI 0.9-4.1, 21 cases, 28 controls) for 30 or more years of time since first exposure. The increase in OR seemed to be independent from that of alcohol or viral infections. Our study showed that the role of occupational exposures in liver carcinogenesis is limited. However, prolonged exposure to organic solvents such as toluene and xylene may represent a risk factor for liver cancer.

Cancer risk in laboratory workers: an emphasis on biological research

BACKGROUND

At the end of the 1980s, several cancer clusters were observed in biological research laboratories. Over time, biological research and the technologies used have been diverse and have involved a wide range of mutagenic or carcinogenic chemical, physical and biological agents.

METHODS

We reviewed 45 published studies on cancer risk among biological research personnel and workers in closely related fields, and numerous reports based on routinely collected data.

RESULTS

Biological research could be associated with an elevated risk for pancreatic cancer, brain tumors, and certain hemopathies. A common limitation of available studies was low statistical power and the absence or inaccuracy of data on individual past exposure.

CONCLUSIONS

Overall, this study suggests a low overall risk of cancer, albeit a higher risk may be suggested for cancers of the pancreas (risk ratios ranging from 0.5 to 6.3) and brain (0.7-9.4), and for non-Hodgkin's lymphoma (0.6-51.5). We suggest ways in which multiple past exposures could be assessed more precisely and emphasize a pressing need to take into account known confounders.

Upper respiratory problems

This article provides an overview of occupational upper respiratory problems which are commonly encountered in a primary care setting and have received formal study. Emphasis is placed on diagnostic methods. The importance of recognizing occupational upper respiratory disorders and offering appropriate therapy is highlighted.

Occupational exposure to formaldehyde and wood dust and nasopharyngeal carcinoma

OBJECTIVES

To investigate whether occupational exposures to formaldehyde and wood dust increase the risk of nasopharyngeal cancer (NPC).

METHODS

A multicentered, population based case-control study was carried out at five cancer registries in the United States participating in the National Cancer Institute's SEER program. Cases (n=196) with a newly diagnosed NPC between 1987 and 1993, and controls (n=244) selected over the same period from the general population through random digit dialing participated in structured telephone interviews which inquired about suspected risk factors for the disease, including a lifetime history of occupational and chemical exposure. Histological type of cancer was abstracted from clinical records of the registries. Potential exposure to formaldehyde and wood dust was assessed on a job by job basis by experienced industrial hygienists who were blinded as to case or control status.

RESULTS

For formaldehyde, after adjusting for cigarette use, race, and other risk factors, a trend of increasing risk of squamous and unspecified epithelial carcinomas was found for increasing duration (p=0.014) and cumulative exposure (p=0.033) but not for maximum exposure concentration. The odds ratio (OR) for people cumulatively exposed to >1.10 ppm-years was 3.0 (95% confidence interval (95% CI) 1.3 to 6.6) compared with those considered unexposed. In analyses limited to jobs considered definitely exposed, these trends became stronger. The associations were most evident among cigarette smokers. By contrast, there was no association between potential exposure to formaldehyde and undifferentiated and non-keratinising carcinomas. There was little evidence that exposure to wood dust increased risk of NPC, as modest crude associations essentially disappeared after control for potential exposure to formaldehyde.

CONCLUSIONS

These results support the hypothesis that occupational exposure to formaldehyde, but not wood dust, increases risk of NPC. This association seems to be specific to squamous cell carcinomas. Established cohorts of workers exposed to formaldehyde and wood dust should continue to be monitored for NPC and other respiratory cancers. Future studies of NPC should take into account histological type in assessing risk from environmental and host factors.

Mortality among chemical plant workers exposed to acrylonitrile and other substances

OBJECTIVES

To examine the association between exposure to acrylonitrile (AN) and cancer mortality by performing an independent and extended historical cohort study of workers from a chemical plant in Lima, Ohio included in a recent NCI-NIOSH study.

METHODS

Subjects were 992 white males who were employed for three or more months between 1960 and 1996. We identified 110 deaths and cause of death for 108. Worker exposures were estimated quantitatively for AN and qualitatively for nitrogen products. Statistical analyses included U.S. and local county-based SMRs and internal relative risk regression of internal cohort rates.

RESULTS

No statistically significant excess mortality risks were observed among the total cohort for the cancer sites implicated in previous studies: stomach, lung, breast, prostate, brain, and hematopoietic system. We observed a statistically significant bladder cancer excess based on four deaths (SMR=7.01, 95% CI=1.91-17.96) among workers not exposed to AN. Among 518 AN-exposed workers, we observed a not statistically significant excess of lung cancer based on external (SMR=1.32, 95% CI=.60-2.51) and internal (RR=1.98, 95% CI=.60-6.90) comparisons. Although the trends were not statistically significant, exposure-response analyses of internal cohort rates showed monotonically increasing lung cancer rate ratios with increasing AN exposure, with RRs exceeding 2.0 in the highest exposure categories.

CONCLUSIONS

With the possible exception of lung cancer, this study provides little evidence that exposure to AN at levels experienced by Lima plant workers is associated with an increased risk of death from any cause including the implicated cancer sites.