LUNG DISORDERS RESULTING FROM THE INHALATION OF METALS

A comprehensive summary of disease variants implicated in metal allergy

Allergic disease represents one of the most prominent global public health crises of the 21^st century. Although many different substances are known to produce hypersensitivity responses, metals constitute one of the major classes of allergens responsible for a disproportionately large segment of the total burden of disease associated with allergy. Some of the most prevalent forms of metal allergy - including allergic contact dermatitis - are well-recognized; however, to our knowledge, a comprehensive review of the many unique disease variants implicated in human cases of metal allergy is not available within the current scientific literature. Consequently, the main goal in composing this review was to (1) generate an up-to-date reference document containing this information to assist in the efforts of lab researchers, clinicians, regulatory toxicologists, industrial hygienists, and other scientists concerned with metal allergy and (2) identify knowledge gaps related to disease. Accordingly, an extensive review of the scientific literature was performed - from which, hundreds of publications describing cases of metal-specific allergic responses in human patients were identified, collected, and analyzed. The information obtained from these articles was then used to compile an exhaustive list of distinctive dermal/ocular, respiratory, gastrointestinal, and systemic hypersensitivity responses associated with metal allergy. Each of these disease variants is discussed briefly within this review, wherein specific metals implicated in each response type are identified, underlying immunological mechanisms are summarized, and major clinical presentations of each reaction are described.Abbreviations: ACD: allergic contact dermatitis, AHR: airway hyperreactivity, ASIA: autoimmune/ autoinflammatory syndrome induced by adjuvants, BAL: bronchoalveolar lavage, CBD: chronic beryllium disease, CTCL: cutaneous T-cell lymphoma, CTL: cytotoxic T-Lymphocyte, DRESS: drug reaction with eosinophilia and systemic symptoms, GERD: gastro-esophageal reflux disease, GI: gastrointestinal, GIP: giant cell interstitial pneumonia, GM-CSF: granulocyte macrophage-colony stimulating factor, HMLD: hard metal lung disease, HMW: high molecular weight, IBS: irritable bowel syndrome, Ig: immunoglobulin, IL: interleukin, LMW: low molecular weight, PAP: pulmonary alveolar proteinosis, PPE: personal protective equipment, PRR: pathogen recognition receptor, SLE: systemic lupus erythematosus, SNAS: systemic nickel allergy syndrome, Th: helper T-cell, UC: ulcerative colitis, UV: ultraviolet.

Black bronchoscopy

A presence of black pigmentation involving the endobronchial tree is not uncommon. It was first described in the literature in association with occupational exposure in the early 1940s. However, in 2003, Packham and Yeow formally used the term black bronchoscopy to describe endobronchial metastasis from a malignant melanoma. Hyperpigmentation of the airway, however, is associated with multiple etiologies such as congenital disease, inborn errors of metabolism, infections, environmental exposures, neoplasm, and iatrogenic causes. Although the majority of these conditions are benign, a proper diagnosis is important for optimal management. In this article, we review the etiology of black bronchoscopy and discuss its presentations and current management guidelines.

Signal pathway of hippocampal apoptosis and cognitive impairment of mice caused by cerium chloride

Experimental studies have demonstrated that lanthanides could impair cognitive functions of children and animals, but very little is known about the hippocampal apoptosis and its molecular mechanism. The study investigated the signal pathway of hippocampal apoptosis induced by intragastric administration of CeCl(3) for 60 consecutive days. It showed that cerium had been significantly accumulated in the mouse hippocampus, and CeCl(3) caused hippocampal apoptosis and impairment of spatial recognition memory of mice. CeCl(3) effectively activated caspase-3 and -9, inhibited Bcl-2, and increased the levels of Bax and cytochrome c, promoted accumulation of reactive oxygen species in the mouse hippocampus. It implied that CeCl(3)-induced apoptosis in the mouse hippocampus could be triggered via mitochondrion-mediated pathway. Our findings suggest the need for great caution to handle the lanthanides for workers and consumers.

Occupational asthma in industry

Occupational or professional asthma is defined as adult asthma, i.e., an inflammatory respiratory disease characterized by the presence of variable airflow limitation or bronchial hyperreactivity secondary to conditions and causes associated with a given occupational or working environment - not with stimuli found outside the workplace. Depending on the physiopathological mechanism involved, a distinction is made between immune asthma (with or without IgE mediation) and non-immune asthma. It is difficult to establish the relationship among the symptoms of asthma, the patient's professional activity and the presence or absence of sensitization to certain agents in the working environment. Guided compilation of the case history and measurement of nonspecific bronchial hyperreactivity and bronchial inflammation are currently essential in the diagnostic approach to occupational asthma. Whenever possible, allergists should establish the cause-effect relationship in occupational asthma, as required by the medical-legal and social implications of the disease. Occupational asthma remains a minority diagnosis among occupational diseases in general. Adequate personnel training and the creation of diagnostic centers may help to ensure correct and rapid detection of this disease.

In vitro alveolar cytotoxicity of soluble components of airborne particulate matter: effects of serum on toxicity of transition metals

Respiration of fossil fuel-derived airborne particulate matter (PM) has been linked to various pulmonary disorders. Transition metals contained in such PM, such as zinc, iron and vanadium, have been suggested as the primary culprits in PM-induced pulmonary distress by rat instillation studies. In this study, the cytotoxicity of zinc, iron, and vanadium on confluent monolayers of rat alveolar epithelial cells was evaluated as the inhibition of cellular succinate dehydrogenase metabolic activity as quantified via the MTT assay. In addition, the effect of culture medium serum concentration on the toxicities of these three metals was investigated. Of the three metals tested, zinc was the most toxic, with an EC50 of 0.6 mM in culture medium with 10% serum; vanadium and iron had EC50's of 3 and 4 mM, respectively. Serum in culture medium was found to substantially reduce the apparent toxicity of zinc: EC50's for zinc ranged from 0.6 mM in 10% serum to 0.1 mM in serum-free medium. Zinc toxicity analyses in various culture medium conditions demonstrated that the toxicity-reducing effect of serum was due largely and perhaps entirely, to serum albumin. Some, but not all of the effect of serum and albumin on zinc toxicity is apparently due to zinc-albumin binding.

Memory deficits and industrial toxicant exposure: a comparative study of hard metal, solvent and asbestos workers

Memory functioning was examined in ex-factory workers with hard metal disease, resulting from exposure to alloys utilizing cobalt. Since these workers are also exposed to organic solvents and may suffer from chronic hypoxia as a result of their pulmonary disorder, solvent and asbestos workers, as well as an unexposed matched sample, served as controls. Results demonstrated deficits in the allocation of attentional resources and in short-term verbal memory. A pattern of findings across several tests suggested that repetition or delay is important for adequate memory performance in individuals exposed to hard metal, implicating a deficit in encoding or slowed consolidation.

Eosinophilic lung reaction to aluminium and hard metal

A nonsmoker drill polisher with interstitial lung disease is presented. The environmental exposure was mainly to aluminum oxide, aluminum silicate, and hard metals. Bronchoalveolar lavage revealed high eosinophilia, and transbronchial biopsy specimen disclosed interstitial pneumonia with giant cell infiltrates and peribronchiolar accumulation of macrophages laden with opaque dust. Mineralogic studies done from the tissue revealed a high concentration of exogenous particles that were identified as hard metals and aluminum silicate. These findings are compatible with hard metal pneumoconiosis.

Localization and health effects of lanthanum chloride instilled intratracheally into rats

Lanthanum (La) is one of the rare earths used in diverse high technology fields for which sufficient data for assessing its health effects have been lacking. The biological effects and metabolic behaviors of La were studied by instilling lanthanum chloride intratracheally into male Wistar rats. The distribution of La among tissues revealed that the metal remains mostly in the lung with a biological half-time of 244 days. The subcellular localization by transmission electron microscopy with an X-ray microanalyzer indicated that La localizes in macrophages as high electron-dense granular inclusions in lysosomes and on the cell surface and basement membranes of type I pneumocytes among lung cells. The pulmonary health effects were examined by biological indices of the bronchoalveolar lavage fluid (BALF) and lung tissue. The acute toxicity estimated by lactate dehydrogenase activity in BALF was comparable to those of yttrium and copper that had been determined under the same protocol. Microscopic examination of the lung indicated a characteristic increase in the number of eosinophils.

Respiratory hazards in hard metal workers: a cross sectional study

A cross sectional study was conducted on 513 employees at three hard metal plants: 425 exposed workers (351 men, 74 women) and 88 controls (69 men, 19 women). Cough and sputum were more frequent in workers engaged in "soft powder" and presintering workshops compared with controls (12.5% and 16.5% v 3.5%). Spirometric abnormalities were more frequent among women in sintering and finishing workshops compared with control women (56.8% v 23.8%) and abnormalities of carbon monoxide test were more frequent in exposed groups than in controls; this difference was more pronounced in women (31.4% v 5.6%) than in men (18.5% v 13%). No significant correlation was observed between duration of exposure and age adjusted lung function tests. Slight abnormalities of chest radiographs (0/1, 1/1 according to ILO classification) were more frequent in exposed men than controls (12.8% v 1.9%) and mostly in soft powder workers. In subjects with abnormal chest radiographs FVC, FEV1 and carbon monoxide indices (fractional uptake of CO or CO transfer index or both) were lower compared with those with normal chest radiographs. Although relatively mild, the clinical, radiological, and functional abnormalities uncovered call for a regular supervision of workers exposed to hard metal dust.

Approach to the patient with diffuse lung disease

When evaluating diffuse lung infiltrates, the clinician should place special emphasis on the acuity of symptoms, nonpulmonary complaints and findings, environmental exposures, and risk factors for immunosuppressive diseases. Certain radiographic features, such as the distribution of opacities, hilar adenopathy, Kerley-B lines or pneumothorax, or pulmonary function tests demonstrating air flow limitation also narrow the differential diagnosis. One can direct the subsequent workup based on the narrowed differential diagnosis, the pace of disease, the activity of the ongoing inflammatory-immune process, and the age, overall medical condition, and wishes of the patient. Unless a specific diagnosis (for example, hypersensitivity pneumonitis, the treatment of which is withdrawal of the offending agent) can be made, therapy of noninfectious diffuse lung disease is quite unsatisfactory. Immunosuppressive therapy is indicated to arrest the active inflammatory process with the hope that objective signs of improvement will occur after a 3- to 12-month course. Important areas of basic research in pulmonary fibrosis include cell-cell and cell-matrix interactions in the lung interstitium and delineation of fibroblast biology and cytokine-mediated lung connective tissue pathology. More successful therapies will probably evolve from better understanding of the molecular and cellular biology of the lung fibrogenic process.

Chromium, cobalt and lanthanum in lung, liver and kidney tissue from deceased smelter workers

Lung, liver and kidney tissue concentrations of chromium, cobalt and lanthanum from 66 deceased copper smelter workers have been compared with 14 controls. Samples were taken in connection with ordinary autopsies at the local hospital. Neutron activation analysis was used. The mean exposure time for the smelter workers was 30 y, the mean time to date of death after termination of exposure was 7.4 y. A four-fold increase of chromium (p = 0.001) and a two-fold increase of cobalt (p less than 0.001) and lanthanum (p = 0.013) in lung tissue was found for smelter workers compared to controls. Of the smelters nearly one third died from malignancies (approximately 10% from respiratory cancer) and approximately 45% from cardiovascular disease. In the control group nearly 80% died from cardiovascular diseases and no malignancies were found. In lung tissues the concentration of chromium, cobalt and lanthanum did not decline with time after exposure had ended, indicating a long biological half-time. The causes of death could not be related to a single factor. The findings indicate a multifactorial genesis.