Chromate lung cancer with special reference to its cell type and relation to the manufacturing process

Lung Cancer Risk in Male Dentists: A Retrospective Cohort Study in Japan, 1964–1997

It is reported that dentists are exposed to heavy metals in their clinics. To assess the risk of developing lung cancer among male Japanese dentists, we conducted a retrospective cohort study of 3,314 members of Osaka Dental Association (Osakafu-Shikaishikai). During 1964-1997, 39 were diagnosed with lung cancer, which figure was obtained from the file of the Osaka Cancer Registry. The observed number of lung cancers was compared with the expected number calculated by multiplying the number of person-years at risk by the corresponding age- and calendar time-specific incidence rate from the Osaka Cancer Registry data. The male dentists had no significantly different risk than general population.(O/E=1.01, 95%CI=0.72-1.39). Contrary to expectation, these findings indicate that Japanese dentists had almost the same overall risk of developing lung cancer as the general population.

Association of chromium exposure with multiple primary cancers in the nasal cavity

A 56-year-old man who had worked at a chromate factory for 13 years developed squamous cell carcinoma of the left nasal cavity 11 years after retirement. He received intra-arterial chemotherapy, followed by surgery. Two years later, an adenocarcinoma was identified in the same nasal cavity just above the previous surgical region. He underwent medial maxillectomy in combination with postoperative irradiation. He has been disease free for 5 years after the second surgery. Microsatellite markers were examined in the second tumor specimen as a possible factor for carcinogenesis; however, replication errors were not observed in any of four loci (D2S123, D3S1067, TP53, D18S474) tested. The present case seems to have resulted from long-term exposure to chromium and, to our knowledge, is the first reported case with multiple primary cancers in the nasal cavity associated with chromium exposure.

Chromium

Chromium occurs primarily in the trivalent state (III), which is the most stable form, or in the hexavalent state (VI), which is a strong oxidizing agent. Elemental chromium (0) does not occur naturally on earth. Trivalent chromium (III) is an essential trace metal necessary for the formation of glucose tolerance factor and for the metabolism of insulin. Commercial applications of chromium compounds include tanning (III), corrosion inhibition, plating, glassware-cleaning solutions, wood preservatives (VI), manufacture of safety matches, metal finishing (VI), and the production of pigments (III, VI). Hexavalent chromium (VI) contaminated local soil when chromium waste slag was part of the fill material present in residential, public, and industrial areas. In some urban areas, about two-thirds of the chromium in air results from the emission of hexavalent chromium from fossil fuel combustion and steel production. The remaining chromium in air is the trivalent form. The residence time of chromium in air is < 10 days, depending on the particle size. Trivalent compounds generally have low toxicity and the gastrointestinal tract poorly absorbs these compounds. Hexavalent chromium is a skin and mucous membrane irritant and some of these hexavalent compounds are strong corrosive agents. Hexavalent chromium compounds also produce an allergic contact dermatitis characterized by eczema. Sensitivity to trivalent compounds is much less frequent, but some workers may react to high concentrations of these compounds. Hexavalent chromium is recognized by the International Agency for Research on Cancer and by the US Toxicology Program as a pulmonary carcinogen. The increased risk of lung cancer occurs primarily in workers exposed to hexavalent chromium dust during the refining of chromite ore and the production of chromate pigments. Although individual studies suggest the possibility of an excess incidence of cancer at sites outside the lung, the results from these studies are inconsistent.

Roles of epidemiology, pathology, molecular biology, and biomarkers in the investigation of occupational lung cancer

The pathology and molecular biology of lung cancer demonstrate that these tumors evolve through a series of mutations, molecular changes, and corresponding morphologic changes. To elucidate how occupational and environmental factors influence lung cancer histogenesis it is important not only to understand epidemiology and the interactions between etiologic agents but also to integrate information from pathology, biochemistry and molecular biology. This review focuses on the range of techniques currently available for characterizing lung cancer and how their prudent use can be beneficial in the identification of occupational carcinogens. Because many occupational and environmental lung cancers are caused by multiple etiologic agents, the integration of histology with cellular, biochemical and molecular biomarker techniques may provide new approaches for understanding the disease process.

Characteristics of chromate workers' cancers, chromium lung deposition and precancerous bronchial lesions: an autopsy study

The characteristics of lung cancers induced by inhaled chromate were studied in 13 consecutive autopsies on male ex-chromate workers. In addition to histopathology, we examined: (1) the relationship between the occurrence of lung cancer and the amount of chromium (Cr) deposited in the lung as determined by atomic absorptiometry and (2) the chronological changes in five precancerous lung lesions followed by bronchoscopy till death. Twenty-one cancers were identified, including 16 lung tumours observed either during follow-up or at autopsy. Of these 16 tumours, 13 were found in six subjects, implying a high frequency of multiple cancers. Eleven (69%) out of the 16 tumours were of squamous cell type (including carcinoma in situ), this being twice as frequent as in age-matched controls. A further characteristic was predominance in the central part of lung (69%). The lung Cr burden was very much higher [40-15,800 micrograms g-1 (dry)] in patients with lung tumours than in those without (8-28 micrograms g-1). Five of the precancerous lesions followed by bronchoscopy originated at bronchial bifurcations. Four of these cases showed a return to normal histology at autopsy even without therapy, and the other did not progress.

Mechanisms of chromium carcinogenicity and toxicity

Chromium, like many transition metal elements, is essential to life at low concentrations yet toxic to many systems at higher concentrations. In addition to the overt symptoms of acute chromium toxicity, delayed manifestations of chromium exposure become apparent by subsequent increases in the incidence of various human cancers. Chromium is widely used in numerous industrial processes, and as a result is a contaminant of many environmental systems. Chromium, in its myriad chemical forms and oxidation states, has been well studied in terms of its general chemistry and its interactions with biological molecules. However, the precise mechanisms by which chromium is both an essential metal and a carcinogen are not yet fully clear. The following review does not seek to embellish upon the proposed mechanisms of the toxic and carcinogenic actions of chromium, but rather provides a comprehensive review of these theories. The chemical nature of chromium compounds and how these properties impact upon the interactions of chromium with cellular and genetic targets, including animal and human hosts, are discussed.

Metal concentrations in lung tissue of subjects suffering from lung cancer

Concentrations of nine metals (Fe, Ca, Mg, Zn, Cu, Co, Ni, Pb and Cr) concentrations in lung tissues from 224 lung cancer cases were compared with those in other cases to achieve an understanding of their contribution to the development of lung cancer and the varieties after the development of cancer. Comparisons of metal concentrations in each cell type of lung cancer were also performed. All cases were collected from routine autopsies in Tokyo and Saitama, Japan. The copper concentration in tissue from lung cancers was significantly higher than that in other specimens, although calcium, magnesium, zinc and cobalt concentrations in lung cancers were significantly lower than those in other cases. There were no significant differences in the 99% intervals (excluding extremely high values for occupationally exposed cases) for chromium, nickel and lead concentrations between lung cancers and other cases, although these values were lower in lung cancers. However, in comparisons of men only, the chromium concentration, the degree of lung contamination and the severity of pulmonary emphysema in lung cancer cases were significantly higher than those in other specimens. Moreover, percentages of lung cancer in men at each degree of contamination and each severity of emphysema increased with increasing grades. Thus, this finding could be evidence that the exposure to contaminants other than chromium and nickel in the air had affected the development of lung cancer, except for occupationally exposed individuals. Therefore, almost all chromium and nickel in lung tissue might not deposit in carcinogenic forms such as hexavalent chromium or nickel subsulfide.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between occupation and lung cancer as analyzed by age and histologic type

The information on occupations obtained in Finland's 1970 census was linked with the files of the Finnish Cancer Registry from 1971 through 1980 in order to establish the occupational group-specific relative risks (RR) of lung cancer. The distribution of lung cancers into histologic types varied with the age of the patients at the time of diagnosis. When 38 high-risk occupational groups were combined, the age-specific distribution of lung cancer into histologic types did not differ significantly from the corresponding distribution for other economically active men. Of individual occupational groups, young farmers had a higher RR of small cell carcinoma than older farmers or other economically active young men. Besides their high overall lung cancer risk, miners and quarriers had a very high risk of small cell carcinoma as compared with other economically active men. Servicemen and repairmen in the metal industry had a high risk of epidermoid carcinoma. Welders had a high risk of epidermoid carcinoma, but their risk of small cell carcinoma was lower than expected. There were no other excess risks of any histologic type of lung cancer attributable to occupational factors.

One hundred years of chromium and cancer: a review of epidemiological evidence and selected case reports

The present review is motivated by the fact that 100 years have passed since the first cancer case in a chromium worker was reported in Scotland. Old and recent case reports and epidemiological studies among chromate workers are reviewed to elucidate the importance of valency states and water solubility of chromium compounds for carcinogenic potency. It is concluded that all chromium[VI] compounds should be considered carcinogenic among exposed populations, and that no evidence has been presented indicating that human exposure to chromium[III] is associated with increased cancer risk. Strong evidence has been presented that zinc chromate is a potent carcinogen and suggests that calcium chromate may be a potent carcinogen. Evidence also suggests that water-soluble chromates in general may be more potent carcinogens than those with low solubility. Primary and secondary prevention of chromate-related cancer and the success in preventive measures are briefly discussed, and recommendations for future research are made.

Lung cancer in chromate workers: high-risk group for multiple lung cancer

We diagnosed eight (8.9%) lung cancer patients in 90 workers exposed to chromate compounds. The duration of exposure ranged from 8 to 31 years, with a mean value of 18 +/- 8 years. The histological classification was squamous-cell carcinoma in seven patients and adenocarcinoma in one patient. The site of origin of the primary tumors was located peripherally in two (25%) and centrally in six (75%). All but one of these patients underwent surgery. In three (37.5%) of these patients, lung cancer foci were detected during the postoperative follow-up by sputum cytology and bronchoscopy. Two of these three patients had multicentric cancer foci: double primary early squamous-cell carcinoma in one and early squamous-cell carcinoma + small-cell lung cancer in the other. In a high-risk group such as chromate workers, we should emphasize early detection of lung cancer by serial sputum cytology, chest x-rays, and bronchoscopy. Lung cancer patients with chromate exposure should be treated with due regard to the possibility of synchronous or metachronous cancer.

Histologic types of lung cancers among male Japanese copper smelter workers

This study was done to investigate which histologic type of lung cancer is prevalent among male Japanese copper smelter workers. A panel of eight pathologists was asked to diagnose uniformly prepared materials for 19 occupational series, 87 nonoccupational bronchogenic carcinomas, and 14 benign lesions. The consensus diagnosis was used as reference. The reference diagnoses and the originals without materials employed for verification were designated as finals. Squamous cell carcinoma was the most frequent cell type in the occupational group, which comprised 21 (75.0%) of 28 histologically proven cases. There were three (10.7%) small cell carcinomas, one (3.6%) large cell carcinoma, and three (10.7%) adenocarcinomas. The proportion of Kreyberg group I in the occupational cases was significantly larger than that of lung cancers in the population-based cancer registries in Japan. These findings are compatible with Kreyberg's hypothesis. Above all, squamous and small cell carcinomas were prominent and appeared to be environmentally related bronchogenic carcinomas.

Metal-induced lethality and mutagenesis: possible role of apurinic intermediates

The possible mechanisms by which various metals exert their mutagenic effects were investigated using both chemical and biochemical techniques. Ions of Cu, Ni and Cr enhanced the release of either adenine [Cu(II) and Ni(II)] or guanine [Cr(VI)] from DNA as measured in a chromatography assay, suggesting the possible importance of depurination in metal-induced mutagenesis. Transfection experiments with single-stranded bacteriophage phi X174 DNA indicated that micromolar levels of Cu(II), Cr(III), Cr(VI) and Pt(IV) are capable of causing extensive lethal damage to the phage DNA. In case of Cu(II) and Pt(IV) this damage proved mutagenic for phi X174 am3 after transfection of DNA into SOS-induced spheroplasts. For Cu(II) mutagenesis is likely due to the release of adenine residues from the phage DNA based on the abolishment of mutagenesis by alkali and the observed specificity of the phage revertants. The enhancement of the adenine depurination rate by Cu(II) was estimated to be as high as 10,000-fold.

Biological, pathological and clinical features of small cell lung cancer

Small cell lung cancer, which is not uncommon, and is one of the most malignant and relatively well investigated solid tumors of adults, has been reviewed concerning its biology, pathology and clinical aspects. Although it is histologically very simple, its poorly differentiated epithelial cell characteristics are complicated by features of neuroendocrine cells, such as amine and peptide hormone production and specific enzyme activities, some of which have been found to be good monitoring markers during and after treatment. Because of the relative ease of establishing cell lines in vitro, cell characteristics have been studied in detail. This has led to subtyping of cell lines and may further lead to subtyping of histology. However, accumulation of further evidence has disclosed exceptions and unclassifiable cell lines. The same can be said about chromosomal abnormality. The reactivity of monoclonal antibodies and also oncogenes supports the prevalent concept discriminating small cell cancer from non-small cell cancer. However, concepts concerning histogenesis are still changing. Although it is one of the solid tumors most sensitive to radiation and chemotherapy, the response rate of the tumor to non-surgical treatment appears to have reached a plateau. In order to make a breakthrough in the treatment, strategies based on biological findings must be applied.

Occupation and lung cancer risk. An analysis by histologic subtypes

The relationships between cigarette smoking, occupational exposures, dietary vitamin A and lung cancer is explored in a case-control study. The study is based on 1002 primary lung cancers among white men and 1119 white male controls between 35 and 79 years of age admitted to Roswell Park Memorial Institute from 1957 to 1965. Four hundred sixty-four lung cancer cases were classified as one of the three major histologic cell types: squamous, small cell, or adenocarcinoma. Each of the three main histologic types displayed a statistically significant trend of increasing risk associated with increasing consumption of cigarettes with the strongest relationship being seen for small cell carcinoma (odds ratio for 40+ pack-years = 17.5) and the weakest with adenocarcinoma (odds ratio for 40+ pack-years = 6.7). Increasing risk for squamous cell cancer was seen with increasing duration of exposure to all lung carcinogens, asbestos, and aromatic hydrocarbons. Small cell carcinomas were not associated with any of the occupational exposure categories studied with the exception of asbestos exposure in light smokers. Increasing risk of adenocarcinoma was seen with increasing duration of employment in occupations with potential exposure, but only for light smokers. Dietary vitamin A consumption did not confound the occupational associations. Hypotheses have been generated regarding interplay of risk factors in the etiology of different histologic subtypes of lung cancer. Studies of specific histologic types of lung cancer are needed to elucidate the role of various environmental and occupational risk factors.