Cancer of respiratory organs among workers at a nickel refinery in Norway

Cancer mortality and exposure to nickel and chromium compounds in a cohort of Italian electroplaters

BACKGROUND

Nickel and chromium-VI compounds are carcinogens for lung cancer, although it is still debated if there is an increased risk at low levels of exposure and for other cancers.

METHODS

In a cohort of 2991 Italian electroplaters, a proportion of whom were exposed to low levels of nickel and/or chromium, cumulative exposure to their compounds was obtained by multiplying average concentrations of the metals in each electroplating tank by duration of employment in the company. The association of exposure to compounds with mortality was assessed by multivariable Cox models.

RESULTS

No cancer site was associated with chromium exposure controlling for nickel, whereas exposure to nickel significantly increased mortality from lung, rectal, and kidney cancers, even after adjusting for exposure to chromium.

CONCLUSIONS

Study results suggest that exposure to nickel compounds may increase the risk of lung cancer even below its occupational exposure limit and indicate possible associations with other cancer sites.

Systematic screening for occupations and occupational exposures in head and neck squamous cell carcinoma patients

PURPOSE

The importance of occupational exposures in patients with head and neck squamous cell carcinomas (HNSCC) has received little attention.

METHODS

In a single-center study, we prospectively characterized occupational exposures in 154 HNSCC cancer patients in a systematic occupational consultation and examined the association between most frequent exposures, HNSCC stage and localization.

RESULTS

Patients occupied a mean of 3.3 different positions during their working life. The prevalence of asbestos, the most frequent exposure (46 patients; 29.9%) was higher than in the French population > 50 years. Other frequent exposures were solvents (n = 26; 16.9%) and silica (n = 19; 12.3%). For 37 patients (24%) a possible link was identified between occupational exposures and HNSCC. Duration of asbestos exposure was significantly higher (p = 0.04) in patients with hypopharyngeal and laryngeal cancer compared to other localizations.

CONCLUSIONS

Occupational exposures are frequent in patients with HNSCC and should receive increased attention by physicians.

Descriptive Epidemiology of Cancer of the Larynx in the Province of Torino, Italy

Age-standardized incidence rates of cancer of the larynx in men from 1965–1969 were 14.7/100,000/year in the city of Torino and 8.4 in the non-metropolitan area of the province. These rates are among the highest in Europe. The geographical distribution of cancer of the larynx has been investigated in the non-metropolitan area considering two geographical entities, i.e., the 291 towns and the 12 ecological zones/subzones of the area. The incidence of cancer of the larynx in men was unrelated to the population of towns in 1961, whereas it was positively correlated to indexes of general industrialization as well as to those related to industrialization in the mechanical processes. Tobacco and alcohol consumption have not been taken into account. In order to validate the methodology, the investigation was extended to bladder cancer and to cancer in children. The former was correlated with general and chemical + rubber industrialization, whereas the latter was not correlated with any industrial process.

Respiratory cancer mortality and incidence in an updated cohort of Canadian nickel production workers

Respiratory cancer mortality and incidence were examined in an updated cohort of >56,000 Canadian nickel mining and refining workers. There was little evidence to suggest increased lung cancer risk in workers who had no experience in high-risk sintering operations that were closed by 1972, apart from that which would be expected from probable increased smoking prevalence relative to the comparison population. There was no substantive evidence of increased laryngeal cancer risk in the cohort, nor was there evidence of increased pharyngeal cancer risk in nonsinter workers. Nasal cancer incidence was elevated in nonsinter workers, but excess risks appeared to be confined to those hired prior to 1960. These findings lead us to tentatively conclude that occupationally-related respiratory risks in workers hired over the past 45 years are either very low or nonexistent.

Nickel and cadmium-induced SLBP depletion: A potential pathway to metal mediated cellular transformation

Both nickel and cadmium compounds have been established as group I carcinogens for several decades. Despite over-whelming evidence of these compounds' carcinogenicity in humans, the specific underlying molecular mechanisms that govern metal induced cellular transformation remain unclear. In this study, we found that there were slightly different effects on decreased SLBP mRNA and protein as well as increased polyA H3.1 in our nickel exposed cells. This suggested that nickel and arsenic have similar effects on canonical histone mRNA transcription and translation. We also saw that the depletion of SLBP protein was reversed by inhibiting the proteosome. Finally, we showed that inhibiting the SLBP mRNA and protein levels were rescued by epigenetic modifiers suggesting that nickel's effects on SLBP may be mediated via epigenetic mechanisms. Taken together these results suggest a similar mechanism by which both arsenic and nickel may exert their carcinogenic effects.

Endoscopic skull base surgery for sinonasal malignancy

Management of malignant neoplasms of the sinonasal tract and skull base is hampered by the relative low incidence and pathologic diversity of patient presentations. Many studies have reported successful outcomes in the endoscopic management of malignancy since 1996, and these are summarized in this article. Nonsurgical adjuvant therapies are important for locoregional control because surgery occurs in a restricted anatomic space with close margins to critical structures, and distant disease is an ongoing concern in these disorders. There remains a need for collaborative consistent multicenter reporting, and international registries have been established to assist in such efforts.

Methods to recognize work-related cancer in workplaces, the general population, and by experts in the clinic, a Norwegian experience

Background

In most countries, the numbers of work-related cancer identified are much lower than are the estimated total burden of cancer caused by exposure at work. Therefore, there is a great need to use all available practical as well as epidemiological methods for identification as well as to develop new methods of recognizing cases of work-related cancers.

Methods

Primarily based on practical experiences from Norway, methods to identify cases of possible work-related cancers in the general population and at workplaces as well as methods to recognize more specific cases after referral to specialized clinics are reviewed in this publication.

Results

Countries applying a number of the available methods to detect work-related cancer reach a reporting rate of 60 such cases per million, while other countries that do not employ such methods hardly identify any cases. As most subjects previously exposed to cancer causing agents and substances at work are gradually recruited out of work, methods should be versatile for identification of cases in the general population, as well as at work.

Conclusions

Even in countries using a number of the available methods for identification, only a limited fraction of the real number of work-related cancer are notified to the labour inspectorate. Clinicians should be familiar with the methods and do the best to identify work-related cancer to serve prevention.

The content of cadmium, cobalt and nickel in laryngeal carcinoma

INTRODUCTION

The aim of the study was to determine the content of cadmium (Cd), cobalt (Co) and nickel (Ni) in the samples from laryngeal carcinoma in comparison with the level of these elements in the samples of healthy mucous membrane from the same larynx.

MATERIAL AND METHODS

The study was conducted on 43 patients with laryngeal carcinoma. The levels of Cd, Co, and Ni in carcinoma and healthy control tissues was determined by inductively coupled plasma optical emission spectrometry (ICP - OES) using sequential spectrometer.

RESULTS

No significant differences were found between the levels of the Cd, Co, and Ni in laryngeal carcinoma vs tissues without carcinoma. However, it was noted that the concentration of Cd in tumors of patients with metastases to cervical lymph nodes was significantly higher than in tumors without metastases. The content of Co was significantly higher in more advanced laryngeal tumors: in stage-T4 than in stage T3. It is of interest that the levels of Cd, Co and Ni were significantly higher in tumors in patients from rural than urban areas.

CONCLUSIONS

The imbalance in the level of nickel, cadmium and cobalt in laryngeal cancer may be due to a changed cellular metabolism in the cancer process. However, the results of our study reveal the significant differences in the concentration of these metals between patients from urban and rural areas which suggests that this fact may be related to environmental or occupational factors and therefore it requires further study.

Carcinogenicity of occupational nickel exposures: an evaluation of the epidemiological evidence

The health effects documented in recent epidemiological studies of nickel-exposed workers relate to past exposures, mostly of unknown magnitude and unknown nickel speciation. Major studies have been carried out at nickel smelters and refineries. Although each study suffers from some deficiencies, as is common in such retrospective studies, the findings in concert strongly indicate that nickel emitted from the calcining and sintering operations is a potent carcinogen resulting in nasal and pulmonary cancers. Some risk appears to be present in other refinery operations, such as Orford furnace, copper and nickel sulfate, and crushing departments, and one study has suggested a risk associated with soluble nickel compounds in the electrolysis department, although this finding has not been confirmed. Only one study demonstrated an exposure-response relationship, which, however, was not statistically significant. Other studies showed a relationship between increased exposure time and augmented cancer risk. In nickel-using industries, no excess cancer related to nickel exposures has been demonstrated beyond doubt; concurrent exposures to other potential carcinogens constitute a confounding variable that makes interpretation difficult. However, the studies have not excluded that a cancer hazard may be present outside the nickel-producing facilities. Further, case-referent studies of respiratory cancers suggest that a nickel-related etiology may well exist in the nickel-using industries. As the exact identity of the carcinogenic form or forms of nickel remains unknown, exposure to all nickel compounds should be kept as low as reasonably achievable.

Evidence of carcinogenicity in humans of water-soluble nickel salts

BACKGROUND

Increased risks of nasal cancer and lung cancer in nickel refiners have been investigated scientifically and discussed since they were detected in the 1930s. Nickel compounds are considered to be the main cause of the cancer excess. Parts of the nickel producing industry and their consultants oppose the classification of water-soluble nickel salts as human carcinogens, and argue that the risk in exposed workers should be ascribed to other occupational exposures and smoking.

DISCUSSION

Respiratory cancer risks in Welsh, Finnish, and Norwegian nickel refiners add to the evidence of carcinogenicity of water-soluble nickel. In Norwegian refiners, the first epidemiological study in 1973 identified high risks of lung cancer and nasal cancer among long-term electrolysis workers. Risk analyses based on exposure estimates developed in the 1980s supported the view that water-soluble nickel compounds were central in the development of cancer. Recently, new exposure estimates were worked out for the same cohort based on personal monitoring of total nickel and chemical determination of four forms of nickel. Additional data have been collected on life-time smoking habits, and on exposure to arsenic, asbestos, sulphuric acid mists, cobalt, and occupational lung carcinogens outside the refinery. After adjustment for these potential confounding exposures in case-control analyses, the risk pattern added to the evidence of an important role of water-soluble nickel compounds as causes of lung cancer. These Norwegian cancer studies rely on national Cancer Registry data, considered close to complete from 1953 onwards; and on National Population Register data continuously updated with mortality and emigration. Canadian mortality studies--perceived to offer the strongest support to the industry position not to recognise carcinogenicity of water-soluble nickel--appear to suffer from limitations in follow-up time, loss to follow-up, absence of risk analysis with individual exposure estimates, no confounder control, and a likely underestimation of cancer mortality.

CONCLUSIONS

Rejection to recognise water-soluble nickel as a human carcinogen seems to contradict material epidemiological evidence that demonstrates a strong association between water-soluble nickel compounds and risks of lung cancer and nasal cancer. Independent international scientific bodies have classified nickel compounds as carcinogenic to humans, inclusive of water-soluble nickel.

New views on the hypothesis of respiratory cancer risk from soluble nickel exposure; and reconsideration of this risk's historical sources in nickel refineries

INTRODUCTION

While epidemiological methods have grown in sophistication during the 20th century, their application in historical occupational (and environmental) health research has also led to a corresponding growth in uncertainty in the validity and reliability of the attribution of risk in the resulting studies, particularly where study periods extend back in time to the immediate postwar era (1945-70) when exposure measurements were sporadic, unsystematically collected and primitive in technique; and, more so, to the pre-WWII era (when exposure data were essentially non-existent). These uncertainties propagate with animal studies that are designed to confirm the carcinogenicity by inhalation exposure of a chemical putatively responsible for historical workplace cancers since exact exposure conditions were never well characterized. In this report, we present a weight of scientific evidence examination of the human and toxicological evidence to show that soluble nickel is not carcinogenic; and, furthermore, that the carcinogenic potencies previously assigned by regulators to sulphidic and oxidic nickel compounds for the purposes of developing occupational exposure limits have likely been overestimated.

METHODS

Published, file and archival evidence covering the pertinent epidemiology, biostatistics, confounding factors, toxicology, industrial hygiene and exposure factors, and other risky exposures were examined to evaluate the soluble nickel carcinogenicity hypothesis; and the likely contribution of a competing workplace carcinogen (arsenic) on sulphidic and oxidic nickel risk estimates.

FINDINGS

Sharp contrasts in available land area and topography, and consequent intensity of production and refinery process layouts, likely account for differences in nickel species exposures in the Kristiansand (KNR) and Port Colborne (PCNR) refineries. These differences indicate mixed sulphidic and oxidic nickel and arsenic exposures in KNR's historical electrolysis department that were previously overlooked in favour of only soluble nickel exposure; and the absence of comparable insoluble nickel exposures in PCNR's tankhouse, a finding that is consistent with the absence of respiratory cancer risk there. The most recent KNR evidence linking soluble nickel with lung cancer risk arose in a reconfiguration of KNR's historical exposures. But the resulting job exposure matrix lacks an objective, protocol-driven rationale that could provide a valid and reliable basis for analyzing the relationship of KNR lung cancer risk with any nickel species. Evidence of significant arsenic exposure during the processing step in the Clydach refinery's hydrometallurgy department in the 1902-1934 time period likely accounts for most of the elevated respiratory cancer risk observed at that time. An understanding of the mechanism for nickel carcinogenicity remains an elusive goal of toxicological research; as does its capacity to confirm the human health evidence on this subject with animal studies.

CONCLUDING REMARKS

Epidemiological methods have failed to accurately identify the source(s) of observed lung cancer risk in at least one nickel refinery (KNR). This failure, together with the negative long-term animal inhalation studies on soluble nickel and other toxicological evidence, strongly suggest that the designation of soluble nickel as carcinogenic should be reconsidered, and that the true causes of historical lung cancer risk at certain nickel refineries lie in other exposures, including insoluble nickel compounds, arsenic, sulphuric acid mists and smoking.

Fluorescent tracking of nickel ions in human cultured cells

The carcinogenic activity of various nickel (Ni) compounds is likely dependent upon their ability to enter cells and elevate intracellular levels of Ni ions. Water-insoluble Ni compounds such as NiS and Ni(3)S(2) were shown in vitro to enter cells by phagocytosis and potently induce tumors in experimental animals at the site of exposure. These water-insoluble nickel compounds are generally considered to be more potent carcinogens than the water-soluble forms. However, recent in vitro studies have shown similar effects for insoluble and soluble Ni compounds. Using a dye that fluoresces when intracellular Ni ion binds to it, we showed that both soluble and insoluble Ni compounds were able to elevate the levels of Ni ions in the cytoplasmic and nuclear compartments. However, when the source of Ni ions was removed from the culture dish, the intracellular Ni ions derived from soluble Ni compound were lost from the cells at a significantly faster rate than those derived from the insoluble Ni compound. Within 10 h after NiCl(2) removal from the culture medium, Ni ions disappeared from the nucleus and were not detected in the cells by 16 h, while insoluble Ni(3)S(2) yielded Ni ions that persisted in the nucleus after 16 h and were detected in the cytoplasm even after 24 h following Ni removal. These effects are discussed in terms of whole body exposure to water-soluble and -insoluble Ni compounds and consistency with animal carcinogenicity studies.

Occupational exposure and laryngeal and hypopharyngeal cancer risk in central and eastern Europe

A multicenter case-control study was conducted during 1999-2002 in four European countries (Poland, Romania, Russia, and Slovakia) to evaluate the role of occupational exposures in risk of laryngeal/hypopharyngeal cancer. Male cancer cases (34 hypopharyngeal, 316 laryngeal) with full data on occupational history and nonoccupational factors were compared with 728 hospital controls for occupational exposure to 73 suspected carcinogens. Occupational history was evaluated by industrial hygienists blinded to case/control status. Elevated risks for ever exposure to coal dust were found for both hypopharyngeal (odds ratio (OR) = 4.19, 95% confidence interval (CI): 1.18, 14.89) and laryngeal (OR = 1.81, 95% CI: 0.94, 3.47) cancer, with clear dose-response patterns. Inclusion of a 20-year lag in the analysis strengthened these associations. Hypopharyngeal cancer risk was also significantly associated with exposure to mild steel dust (OR = 3.04, 95% CI: 1.39, 6.64) and iron compounds and fumes (OR = 2.74, 95% CI: 1.29, 5.84), without clear dose-response relations. Laryngeal cancer was significantly associated with exposure to hard-alloys dust (OR = 2.23, 95% CI: 1.08, 4.57) and chlorinated solvents (OR = 2.18, 95% CI: 1.03, 4.61), without dose-response relations. A possible link between high formaldehyde exposure and laryngeal cancer was suggested. No association was found for exposure to asbestos or inorganic acid mists. These data indicate that occupational exposure to coal dust may play a role in laryngeal and hypopharyngeal cancer. Other possible relations need further evaluation.

Amplification of the Ect2 proto-oncogene and over-expression of Ect2 mRNA and protein in nickel compound and methylcholanthrene-transformed 10T1/2 mouse fibroblast cell lines

Occupational exposure of humans to mixtures of insoluble and soluble nickel (Ni) compounds correlates with increased incidences of lung, sinus, and pharyngeal tumors. Specific insoluble Ni compounds are carcinogenic to animals by inhalation and induce morphological and neoplastic transformation of cultured rodent cells. Our objectives were to (1) understand mechanisms of nickel ion-induced cell transformation, hence carcinogenesis and (2) develop biomarkers of nickel ion exposure and nickel ion-induced cell transformation. We isolated mRNAs from green nickel oxide (NiO), crystalline nickel monosulfide (NiS), and 3-methylcholanthrene (MCA) transformed C3H/10T1/2 Cl 8 cell lines, and determined by mRNA differential display that nine mRNA fragments were differentially expressed between Ni transformed and non-transformed 10T1/2 cell lines. Fragment R2-5 was expressed at higher steady-state levels in the transformed cell lines. R2-5 had 100% sequence identity to part of the coding region of Ect2, a mouse proto-oncogene encoding a GDP-GTP exchange factor. The 3.9-kb Ect2 transcript was expressed at 1.6- to 3.6-fold higher steady-state levels in four Ni transformed, and in two MCA-transformed, cell lines. Ect2 protein was expressed at 3.0- to 4.5-fold higher steady-state levels in Ni-transformed and in MCA-transformed cell lines. The Ect2 gene was amplified by 3.5- to 10-fold in Ni transformed, and by 2.5- to 3-fold in MCA transformed cell lines. Binding of nickel ions to enzymes of DNA synthesis likely caused amplification of the Ect2 gene. Ect2 gene amplification and over-expression of Ect2 mRNA and protein can cause microtubule disassembly and cytokinesis, contributing to induction and maintenance of morphological, anchorage-independent, and neoplastic transformation of these cell lines. Over-expression of Ect2 protein is a useful biomarker to detect exposure to nickel compounds and nickel ion-induced morphological and neoplastic cell transformation.

Radiographic evidence of pulmonary fibrosis and possible etiologic factors at a nickel refinery in Norway

Animal studies have shown that nickel compounds may induce pulmonary fibrosis, but so far only limited documentation in humans has been available. Radiographs of 1046 workers in a nickel refinery in Norway were read blindly and independently by three NIOSH certified B-readers, according to the ILO standards. Pulmonary fibrosis (PF) was defined as a median reading of ILO score > or = 1/0 and following this criterion, 47 cases (4.5%) were identified. In logistic regression models, controlling for age and smoking, there was evidence of increased risk of PF with cumulative exposure to soluble nickel or sulfidic nickel (p = 0.04 for both). For metallic nickel a p-value of 0.07 was found. For soluble nickel there was a dose-response trend for 4 categories of cumulated exposure. In the group with the highest cumulative exposure to soluble nickel (low exposure as reference), the crude odds ratio for PF was 4.34 (95% CI 1.75-10.77). The risk adjusted for age, smoking, asbestos and sulfidic nickel was 2.24 (0.82-6.16), with a dose-response trend. The corresponding figures for sulfidic nickel were 5.06 (1.70-15.09, crude) and 2.04 (0.54-7.70, adjusted for age, smoking, asbestos and soluble nickel). However, the dose-response trend was less clear for sulfidic nickel. Controlling for estimated asbestos exposure at the refinery tended to increase the odds ratios of soluble and sulfidic nickel. This study indicates that in addition to age and smoking exposure to soluble and sulfidic nickel compounds are risk factors of PF in humans. Since the number of cases identified in this study is small and undetected confounders may have been present, further studies in other cohorts are appropriate.

Respiratory cancer risks associated with low-level nickel exposure: an integrated assessment based on animal, epidemiological, and mechanistic data

Increased lung and nasal cancer risks have been reported in several cohorts of nickel refinery workers, but in more than 90% of the nickel-exposed workers that have been studied there is little, if any evidence of excess risk. This investigation utilizes human exposure measurements, animal data from cancer bioassays of three nickel compounds, and a mechanistic theory of nickel carcinogenesis to reconcile the disparities in lung cancer risk among nickel-exposed workers. Animal data and mechanistic theory suggest that the apparent absence of risk in workers with low nickel exposures is due to threshold-like responses in lung tumor incidence (oxidic nickel), tumor promotion (soluble nickel), and genetic damage (sulfidic nickel). When animal-based lung cancer dose-response functions for these compounds are extrapolated to humans, taking into account interspecies differences in deposition and clearance, differences in particle size distributions, and human work activity patterns, the predicted risks at occupational exposures are remarkably similar to those observed in nickel-exposed workers. This provides support for using the animal-based dose-response functions to estimate occupational exposure limits, which are found to be comparable to those in current use.

Epidemiology of lung cancer

In the United States, lung cancer remains the leading cause of cancer death in both men and women even though an extensive list of risk factors has been well-characterized. Far and away the most important cause of lung cancer is exposure to tobacco smoke through active or passive smoking. The reductions in smoking prevalence in men that occurred in the late 1960s through the 1980s will continue to drive the lung cancer mortality rates downward in men during the first portion of this century. This favorable trend will not persist unless further reductions in smoking prevalence are achieved.

Mortality experience among employees at a hydrometallurgical nickel refinery and fertiliser complex in Fort Saskatchewan, Alberta (1954-95)

OBJECTIVE

To study the mortality experience of workers at a hydrometallurgical nickel refinery and fertiliser complex in Fort Saskatchewan, Alberta, Canada.

METHODS

A total of 1649 male employees of Sherritt International who worked for at least 12 continuous months during the years 1954 to 1978 at the Fort Saskatchewan, Alberta hydrometallurgical nickel refinery and fertiliser complex were followed up for an additional 17 years. Mortality was ascertained from the Canadian mortality data base maintained by Statistics Canada and covered the years 1954-95. Statistics were analysed with Monson's computer program.

RESULTS

Total mortality, when compared with the Canadian population, was significantly below expectation. Fewer deaths were found for circulatory disease, ischaemic heart disease, respiratory disease, neoplasms, digestive cancer, and accidents, poisonings, and violence. Among the 718 men in the group exposed to nickel, there were no deaths due to nasal cavity or paranasal sinus cancer. Fewer deaths were found for all causes, circulatory disease, ischaemic heart disease, neoplasms and digestive cancer. Lower death rates were observed than expected for respiratory malignancies and cancer of the bronchus and lung.

CONCLUSION

No association was found in this study between exposure to nickel concentrate or metallic nickel in the hydrometallurgical refining process and the subsequent development of respiratory cancer.

Malignant Tumors of the Nose and Paranasal Sinuses: A Retrospective Review of 291 Cases

Malignant neoplasms of the nose and paranasal sinuses are not common among the general population. We present a retrospective study of 291 cases of malignant tumors of the nose and paranasal sinuses that were diagnosed in a northern Romanian population over a period of 35 years. We review the etiology, diagnosis, prognosis, and treatment of these tumors.

Nickel

Nickel is an essential element for at least several animal species. These animal studies associate nickel deprivation with depressed growth, reduced reproductive rates, and alterations of serum lipids and glucose. Although there is substantial evidence of an essential status for nickel in animals, a deficiency state in humans has not been clearly defined. Nickel is a silver-white metal with siderophilic properties that facilitate the formation of nickel-iron alloys. In contrast to the soluble nickel salts (chloride, nitrate, sulfate), metallic nickel, nickel sulfides, and nickel oxides are poorly water-soluble. Nickel carbonyl is a volatile liquid at room temperature that decomposes rapidly into carbon monoxide and nickel. Drinking water and food are the main sources of exposure for the general population with the average American diet containing about 300 micrograms Ni/d. Nickel is highly mobile in soil, particularly in acid soils. There is little evidence that nickel compounds accumulate in the food chain. Nickel is not a cumulative toxin in animals or in humans. Almost all cases of acute nickel toxicity result from exposure to nickel carbonyl. The initial effects involve irritation of the respiratory tract and nonspecific symptoms. Patients with severe poisoning develop intense pulmonary and gastrointestinal toxicity. Diffuse interstitial pneumonitis and cerebral edema are the main cause of death. Sodium diethyldithiocarbamate is an investigational drug used to chelate nickel following exposure to nickel carbonyl. Nickel is a common sensitizing agent with a high prevalence of allergic contact dermatitis. Nickel and nickel compounds are well-recognized carcinogens. However, the identity of the nickel compound or compounds, which cause the increased risk of cancer, remains unclear. Currently, there are little epidemiological data to indicate that exposure to metallic nickel increases the risk of cancer, or that exposure to the carcinogenic forms of nickel causes cancer outside the lung and the nasal cavity.

An update of the National Toxicology Program database on nasal carcinogens

Nearly 500 long-term rodent carcinogenicity studies carried out by the National Cancer Institute and the National Toxicology Program were examined, and 12 chemicals were identified that produced nasal tumors: allyl glycidol ether, p-cresidine, 1,2-dibromo-3-chloropropane, 1,2-dibromoethane, 2,3-dibromo-1-propanol, dimethylvinyl chloride, 1,4-dioxane, 1,2-epoxybutane, iodinated glycerol, procarbazine, propylene oxide, and 2,6-xylidine. All 12 of these chemicals produced nasal tumors in rats, and 5 also produced nasal tumors in mice. Most of the nasal carcinogens (1) produced tumor increases in both sexes, (2) produced tumors at other sites as well, (3) had significantly reduced survival at doses that were carcinogenic, and (4) were genotoxic. Only 5 of the 12 nasal carcinogens were administered by inhalation. A variety of different types of nasal cavity tumors were produced, and specific tumor rates are given for those chemicals causing multiple tumor types. Increased incidences of nasal neoplasms were often accompanied by suppurative/acute inflammation, epithelial/focal hyperplasia and squamous metaplasia. However, high incidences of these nonneoplastic nasal lesions were also frequently seen in inhalation studies showing no evidence of nasal carcinogenicity, suggesting that in general nasal carcinogenesis is not associated with the magnitude of chronic toxicity observed at this site.

Carcinogenic response of the nasal cavity to inhaled chemical mixtures

Nasal cancers occur in experimental animals following chronic exposure to a wide range of inhaled chemicals. Although exposure to several of these chemicals is common in industrial as well as domestic environments, epidemiological studies have not provided convincing evidence that exposure to these chemicals individually is associated with nasal cancer in humans. The reverse seems to be true for inhalation of chemical mixtures. The evidence for nasal carcinogenicity of inhaled chemical mixtures in experimental animals is very limited, while there is ample evidence in humans that occupational exposure to certain chemical mixtures is associated with increased risk of nasal cancer. Examples of such (complex) chemical mixtures are wood dust, textile dust, chromium- and nickel-containing materials and leather dust. It is remarkable that these mixtures are aerosols, suggesting that a 'dusty working environment' may increase nasal cancer risk.

Tumors around implants

In 1989, A. G. Apley recommended cautious surveillance of malignant tumors that developed in association with orthopaedic implants. This retrospective review of the Bristol Bone Tumour Register between 1980 and 1992 reports on 240 malignant soft tissue sarcomas. Eighteen developed in the thigh region of patients more than 50 years old, and 4 of these developed in the soft tissues around a hip arthroplasty.

Exposure to nickel compounds and smoking in relation to incidence of lung and nasal cancer among nickel refinery workers

OBJECTIVES

To investigate the relation between occupational hazards among nickel refinery workers and their exposure to different forms of nickel over time and the interaction between smoking and total exposure to nickel.

METHODS

The cohort consisted of 379 workers with first employment 1916-40 and at least three years of employment and 4385 workers with at least one year of employment 1946-83. Data on smoking (ever or never) were available for almost 95% of the cohort. Two analyses were used, indirect standardisation from observed and expected numbers and Poisson regression.

RESULTS

During the follow up 1953-93, 203 new cases of lung cancer were observed v 68 expected (standardised incidence ratio (SIR) 3.0, 95% confidence interval (95% CI) 2.6-3.4) and 32 cases of nasal cancer were observed v 1.8 expected (SIR 18.0, 95% CI 12-25). The Poisson regression analysis showed an excess risk of lung cancer in association with exposure to soluble forms of nickel, with a threefold increase in relative risk (RR) (P < 0.001) and a multiplicative effect of smoking and exposure to nickel. The RRs were 1.1 (95% CI 0.2-5.1) for exposed workers who had never smoked and 5.1 (95% CI 1.3-20.5) for exposed workers who smoked.

CONCLUSION

It is not possible to state with certainty which specific nickel compounds are carcinogenic, but a significant excess risk was found for workers exposed to soluble nickel alone or in combination with other forms of nickel. The present study suggests a multiplicative effect of smoking and nickel exposure.

Occupational and environmental medicine in Norway

A short review is presented on the field of occupational health services (OHSs) and occupational medicine in Norway, with due attention to their history. The current Work Environment Act of 1977 requires management in various industries and enterprises to establish and finance OHSs to obtain advice on matters relating to the work environment. The advisory role of the OHSs, with a focus on prevention, has not yet been adequately implemented. A brief report is given on the current status of occupational health, institutions, teaching in medical faculties, and research activities. As work-related and environmental exposures interact in the causation of diseases, integration of the preventive activities within occupational and environmental medicine is foreseen.

Occupational rhinitis--possible mechanisms of pathogenesis

Occupational rhinitis has been a prescribed industrial disease in the UK since 1907. It has only relatively recently received significant attention from otorhinolaryngologists although numerous studies have been performed in the past by occupational and industrial health physicians. At the present time the precise mechanisms of pathogenesis are unclear and would appear to be multiple. Recently interest has arisen because of compensation claims. Diagnosis made on the basis of the clinical history is subject to two problems: firstly, there is difficulty in differentiating between occupational and nonoccupational rhinitis, and secondly, clinical histories can easily be feigned. Physical signs would be a more reliable indicator of occupational damage to the nasal mucosa if they differ from the signs normally found in allergic or vasomotor rhinitis. In a series of 100 shipyard workers dry atrophic nasal mucosa was found in 66 and septal ulceration in two. From their clinical histories 78 individuals complained of nasal obstruction, 28 of epistaxis, 42 of hyposmia, 10 of anosmia and 90 of rhinorrhoea. Possible pathogenesis is described.

Functional alterations of human blood monocytes after exposure to various nickel compounds in vitro: an effect on the production of hydrogen peroxide

It is generally known that nickel, a metal with distinct carcinogenic properties, can significantly alter the functioning of host defense mechanisms and impair various components of the immune system. In the present study the influence of 3 nickel salts on the production of hydrogen peroxide (H2O2) by human monocytes was examined in in vitro culture. Highly purified, resting and PMA-stimulated normal human monocytes were cultured with subtoxic concentrations of nickel subsulfide nickel sulfate, nickel acetate and manganese chloride. A portion of the cells was cultured with nickel-manganese salt mixture. Following culture cells were tested in an in vitro functional assay for H2O2 production. It has been shown that all nickel salts, used in micromole concentrations, suppressed H2O2 formation both in resting and PMA-stimulated monocytes, while it was not the case when manganese chloride was used for cell cultures. The strongest suppressive effect was manifested by nickel sulfate. The cells subjected to nickel-manganese mixture displayed H2O2 production similar to that of control ones. These results show that nickel salts in micromole concentrations exert a suppressive effect on oxygen-dependent antimicrobial system of human monocytes and manganese prevents this effect.

Mortality studies of machining fluid exposure in the automobile industry. III: A case-control study of larynx cancer

A case-control study of larynx cancer was conducted within a cohort of automobile workers exposed to metal working fluids, commonly referred to as machining fluids (MF). Results are based on 108 cases of larynx cancer and 5:1 matched controls. Risks associated with specific types of MF, as well as specific components of the fluids were evaluated. Based on a retrospective exposure assessment, lifetime exposures to straight and soluble fluids, grinding particulate, biocides, selected metals, sulfur, and chlorine were examined. Exposure to asbestos and acid mists at two of the three study sites was also characterized. Results suggest that straight mineral oils are associated with almost a two-fold excess in larynx cancer risk. There was also evidence of an association with elemental sulfur, commonly added to straight MF to improve the integrity of the materials under extreme pressure and heat. It is not clear whether sulfur is causally related to an excess relative risk of larynx cancer or whether the observed association is the result of unmeasured confounding by another contaminant or process feature. For example, the high stress operations that require MF enriched with sulfur are also more likely to produce polycyclic aromatic hydrocarbons (PAHs) during the process. Thus, the observed association with sulfur may be due to an association with PAH. The finding of excess risk of laryngeal cancer associated with MF is consistent with several previous reports in the literature. This is the first study, however, to distinguish straight mineral oils from other types of MF. Based on these findings, a general reduction in concentrations of straight mineral oil particulate in occupational environments would be prudent.

Rates of regression and progression of dysplastic lesions in the nasal mucosa in nickel workers: a Markov model approach

Nasal epithelial dysplasia is considered a precancerous state. From 1976 through 1989, regular screening for such lesions has been performed among workers at the Falconbridge nickel refinery in Kristiansand. The longitudinal data thus obtained have been evaluated to ascertain to what extent, if any, pre-existing dysplasia can regress when exposure to nickel is reduced. A total of 418 pairs of observations were available from 243 workers. Interpretation of the data is complicated by the fact that dysplasia may remain undetected in small biopsies and the probability of detection of existing dysplasia was, therefore, incorporated into the two-state Markov model. Transition probability rates were estimated by maximum likelihood. The results suggest that regression of dysplasia has taken place and that regression rates increased with time. This finding probably reflects a decreased exposure resulting from a combination of a reduction in airborne nickel, improved personal hygiene and allocation of workers with dysplasia to work in areas with lower nickel exposure. Our results indicate that the chance of developing carcinomas related to nickel exposure is reduced. There are, however, indications that dysplasias continue to develop at a low rate.

A 10-year incidence survey of respiratory cancer and a case-control study within a cohort of nickel mining and refining workers in New Caledonia

The incidence of lung, pleural, nasal, larynx, and pharynx cancer in relation to work in the nickel mining and refining industry was studied from 1978 to 1987 in the male population of the French territory of New Caledonia in the South Pacific. The results showed no greater risk in the population of nickel workers than in the general male population. The incidence of respiratory cancer in New Caledonia was found to be comparable to that of industrialized countries, except for pleural cancer for which there was an excess risk in New Caledonia. A case-control study within the cohort of nickel industry workers comprised 80 lung cancer, 12 larynx cancer, 20 pharynx cancer cases, and 298 controls, and took account of 18 substances to which workers were exposed, five of them nickel compounds. None of the substances, or any other occupational variable, was shown to increase the risk of respiratory cancer, except for cancer of the larynx in relation to level and duration of exposure to dust and engine exhaust fumes on mining sites (odds ratios ranged from five to 5.4 and were significant). These results provide no evidence that exposures specific to the nickel industry in New Caledonia increase the risk of respiratory cancer. This might be due to the involvement of less airborne nickel than the amount observed in positive studies elsewhere. The high incidence of respiratory cancer in New Caledonia, compared with other South Pacific islands, might be attributable to an environmental risk connected with the presence of mineral fibers in the geologic strata, as well as to tobacco and alcohol consumption levels similar to those prevailing in France.

Carcinogenic effects of wood dust: review and discussion

Occupational exposure to wood dust (alone or chemically treated) is associated with an increased risk of developing adenocarcinoma of the nasal cavity. The specific causative agents, i.e., wood dust alone (natural products), wood dust with additives used in the processing or manufacturing of wood products, and/or physical determinants of wood dust and the associated risk factors, are not known or understood. The strongest association of exposure to wood dust and development of nasal cancer is observed in those occupations where workers are exposed to hard wood dust and chemical additives are not used. The time between first occupational exposure to wood dust and the development of adenocarcinoma of the nasal cavity averages 40 years (range 7-70 years). The epidemiological data available are not sufficient to make a definitive assessment between wood dust exposure and increased risk for cancer other than nasal cancer. The toxicity, mutagenicity, and carcinogenicity of wood dust to laboratory animals or in vitro with animal or microbial cells have not been thoroughly studied. Thus there is no direct experimental evidence on the potential hazards of wood dust. Data are insufficient or lacking on 1) wood dust exposure levels in ambient air and worker's breathing zone, and the deposition in the nasal cavity; 2) hard vs. soft wood dusts; 3) particle size and shape; 4) chemical composition of wood dust and the extent of contamination with chemical additives; and 5) interaction between inhaled wood dust, chronic irritation, and tobacco smoking. These data are required so that one can understand the association between wood dust exposure and nasal cavity tumors, along with demographic differences in cancer rates, and to develop strategies for intervention and reduction of disease causing agents in order to reduce risk to wood industry workers.

Tobacco, alcohol, asbestos, and occupational risk factors for laryngeal cancer

Data from a hospital-based case-control study between 1985-1990 were used to examine the effects of tobacco, alcohol, asbestos, and other occupational exposures on laryngeal cancer risk in 194 white men with primary cancer of the larynx and 184 age-matched control subjects. A dose-dependent effect for current cigarette smoking was observed, with higher relative risks (RR) for supraglottic cancer (RR, 21.6 to 68) than for cancer of the glottis (RR, 5.5 to 20.7). Elevated RR for ex-smokers (RR, 4.8) and pipe and cigar smokers (RR, 4.3) did not vary by subsite. The effects of alcohol also showed dose-dependent effects, with higher RR for cancer of the supraglottis than glottis for heavy drinkers (207 ml or more/daily; RR, 9.6 versus 2.5) and binge drinkers (RR, 28.4 versus 8.3). A slightly elevated but not significant association was seen for asbestos exposure and glottic cancer (RR, 1.3). The RR did not increase linearly with the number of years employed in asbestos-related occupations. No relationship was observed between asbestos and cancer of the supraglottis. When examining the data for a synergistic effect of cigarette smoking and asbestos exposure, no excess risk was found. A significantly elevated risk was found for men exposed to diesel fumes (RR, 5.2). Elevated but not significant RR were seen for men chronically exposed to rubber (RR, 6.4) and wood dust or employed as construction laborers, auto mechanics, and other jobs. A significant inverse trend with body mass was observed for cancer of the supraglottis.

Cancer of the nose and paranasal sinuses in the metal industry: a case-control study

The association between nasal cancer and work in the metal industry was investigated in a case-control study located in the province of Brescia, north eastern Italy. Thirty five cases of malignant epithelial neoplasms of the nasal cavity and paranasal sinuses who were resident in the province of Brescia and diagnosed or treated by the ear, nose, and throat department and the radiotherapy unit (Centro Alte Energie) of the Brescia Hospital in the years 1980-9 were included in the study. Controls (102) were patients affected by benign and malignant neoplasms of the head and neck who were resident in the Brescia Province and matched the cases by age and sex. All the subjects were interviewed by telephone. Metal workers showed an increased risk of nasal cancer (odds ratio (OR) 3.1; 90% confidence interval (90% CI) 0.48-20); a higher risk was associated with work in foundries (OR 5.9; 90 CI 0.77-46). Work in wood, leather, and textile industries was also associated with increased risk of nasal cancer.

[Animal experiment studies of carcinogen-induced tumor development in colotomies in relation to suture materials]

To assess the possible risk of cancer in the operated colon after stapling compared with vicryl sutures, the influence of the nickel-containing staples was tested in caecum-resected and carcinogen-treated rats. The nickel-containing staples were seen as a cocarcinogen. The aim of the study was to determine whether a higher incidence of cancer occurs at the anastomotic suture line depending on stapler vs. vicryl sutures after subcutaneous application of carcinogens (dimethylhydrazine). The results show that there is no increased risk of cancer following mechanical stapling.

Mortality of 11,500 nickel workers--extended follow up and relationship to environmental conditions

An extended follow-up from 1977-84 was achieved in a cohort of 11,567 nickel workers engaged in mining, milling and smelting originally studied from 1950-76. Exposure data were incorporated into the analysis. One nasal cancer occurred. The lung cancer Standardized Mortality Ratio beyond 15 years from first exposure was significantly high overall (128) and in miners (153). However, detailed analyses by era of first mining and duration of mining, as well as cumulative exposure to different nickel species, did not appear consistent with an occupational etiology since significant trends were not observed. At the levels of exposure incurred, large increases in lung and nasal cancer, observed in nickel refineries elsewhere, did not occur.

Retrospective cohort mortality study of cancer among sewage plant workers

There is little known about the incidence of cancer among sewage workers. In this paper we examine findings from a retrospective cohort study of 487 white male sewer authority workers employed between January 1950 and October 1979. Vital status was ascertained for 93% of the cohort yielding a total of 6,886 person years. Total mortality from all causes was comparable to that of the general white male U.S. population (Standardized Mortality Ratio [SMR] = 0.91, 95% Confidence Interval [CI] = 0.77-1.07). The cohort was subdivided into those not exposed, and sewer workers who were exposed to sewage effluent, sludge, or wastewater containing chemicals including potential carcinogens. Among the nonexposed group, mortality from all causes was significantly low (SMR = 0.55, 95% CI = 0.33-0.88). Among the exposed sewer workers, mortality from all causes was not significantly different from that of the general white male U.S. population (SMR = 1.00, 95% CI = 0.84-1.19). Mortality from all cancers among exposed sewer workers was slightly higher than that of the general population (SMR = 1.19, 95% CI = 0.79-1.7). Statistically significant elevated mortality ratios were seen for cancer of the larynx (SMR = 7.93, 95% CI = 1.59-23.96), and cancer of the liver (SMR = 5.4, 95% CI = 1.10-16.05). Careful study of the medical and occupational histories of these cases suggested that larynx cancer was possibly work-related, while liver cancer was not. A group estimated to be the highest exposed, composed predominantly of operatives, had a higher directly adjusted death rate from all malignant neoplasms combined compared to all other workers (rate ratio = 1.64). These findings of increased risk of cancer among exposed sewage workers, especially operators, are based on small number of cases and should be interpreted with caution. Studies of larger cohorts are needed to clarify the risk of these cancers among sewage workers.

Cancer incidence among asbestos-exposed chemical industry workers: an extended observation period

A previous study on the incidence of cancer in a cohort of 286 asbestos-exposed electrochemical industry workers observed from 1953 through 1980 has been extended with another 8 years of follow-up. The incidence of cancer was derived from the Cancer Registry of Norway, and the expected figures were calculated by a life table method. During the extended follow-up period from 1981 through 1988, among the cohort members there were 12 new cancer cases versus 14.2 expected (SIR 85, 95% CI 44-158). In a lightly exposed sub-cohort, the extended follow-up revealed 4 cases of lung cancer or pleural mesothelioma (ICD, 7th revision 162-163) versus 1.6 cases expected (SIR 256, 95% CI71-654). In a heavily exposed sub-cohort, the corresponding figures were 3 and 0.5 (SIR 588, 95% CI 118-1,725).

Increased content of chromium and nickel in lung tissues from patients with bronchial carcinoma

Epidemiological studies have shown that occupational exposure to certain chromium and nickel compounds is followed by an increased lung cancer incidence. However, few data exist on the content of these metals in lung cancer patients in general. In the present study, central and peripheral lung tissue, bronchial tissue and hilar lymph nodes were collected from 20 patients with bronchial carcinoma and 21 control individuals, and the tissue concentration of chromium and nickel was measured by use of atomic absorption analysis. Increased levels of both metals were found in cancer patients as compared to controls. Lung tissue concentration of chromium was two-fold increased, while the bronchial wall content of nickel was three times the level in control individuals. Smokers showed a dose-related increase in the deposition of both chromium and nickel. Furthermore, in cancer patients an inverse relationship between smoking and the tissue level of chromium in regional lymph nodes was found, possibly indicating a depressive effect on pulmonary clearance mechanisms. Our results emphasize the possible role of small amounts of chromium and nickel as agents in bronchial carcinogenesis, unrelated to occupation and probably related to tobacco smoking.

Occupational exposure and head and neck carcinoma

An epidemiological case-control study was conducted to investigate occupational risk factors in cancers of the upper respiratory and digestive tract. Cases were men with squamous cell carcinoma of the oropharynx (667), hypopharynx (348), glottis (246), supraglottis (219), epilarynx (204), and 4 subsites of the oral cavity (787). Controls were healthy patients or patients with cancer of another site or another histological type (147 men). Past occupational exposures of cases and controls were compared. The analysis was performed independently for each site of cancer, controlling for age, amount and type of alcohol and tobacco consumption, and state of dentition. Results showed that cancer of the supraglottis was associated with exposure to oil and grease (odds ratio = 2.4; 95% confidence interval 1.0-5.8), and with exposure to cement (odds ratio = 4.2; 95% confidence interval = 1.1-16.4). Cancer of the glottis was also associated with exposure to dye (odds ratio = 6.4; 95% confidence interval = 0.7-56.6). Exposure to flour occurred more frequently among controls than among patients with pharyngeal or oral cancer. This might reflect an association between this occupational exposure and some particular types of cancer included in the control group.