Occupational asthma caused by chromium

Mineral Micronutrients in Asthma

Asthma represents one of the most common medical issues in the modern world. It is a chronic inflammatory disease characterized by persistent inflammation of the airways and disturbances in redox status, leading to hyperresponsiveness of bronchi and airway obstruction. Apart from classical risk factors such as air pollution, family history, allergies, or obesity, disturbances of the levels of micronutrients lead to impairments in the defense mechanisms of the affected organism against oxidative stress and proinflammatory stimuli. In the present review, the impact of micronutrients on the prevalence, severity, and possible risk factors of asthma is discussed. Although the influence of classical micronutrients such as selenium, copper, or zinc are well known, the effects of those such as iodine or manganese are only rarely mentioned. As a consequence, the aim of this paper is to demonstrate how disturbances in the levels of micronutrients and their supplementation might affect the course of asthma.

Scoping Review-The Association between Asthma and Environmental Chemicals

Asthma is one of the most common chronic diseases worldwide affecting all age groups from children to the elderly. In addition to other factors such as smoking, air pollution and atopy, some environmental chemicals are shown or suspected to increase the risk of asthma, exacerbate asthma symptoms and cause other respiratory symptoms. In this scoping review, we report environmental chemicals, prioritized for investigation in the European Human Biomonitoring Initiative (HBM4EU), which are associated or possibly associated with asthma. The substance groups considered to cause asthma through specific sensitization include: diisocyanates, hexavalent chromium Cr(VI) and possibly p-phenylenediamine (p-PDA). In epidemiological studies, polyaromatic hydrocarbons (PAHs) and organophosphate insecticides are associated with asthma, and phthalates, per- and polyfluoroalkyl substances (PFASs), pyrethroid insecticides, mercury, cadmium, arsenic and lead are only potentially associated with asthma. As a conclusion, exposure to PAHs and some pesticides are associated with increased risk of asthma. Diisocyanates and Cr(VI) cause asthma with specific sensitization. For many environmental chemicals, current studies have provided contradicting results in relation to increased risk of asthma. Therefore, more research about exposure to environmental chemicals and risk of asthma is needed.

Toxicity and oxidative stress induced by chromium in workers exposed from different occupational settings around the globe: A review

The present review focused on the levels and toxicological status of heavy metals especially chromium (Cr) in the exposed workers from different occupational settings around the globe and in Pakistan. It was found that exposed workers from leather tanning and metal plating units showed elevated levels of Cr than the workers from other occupational settings. Cr and other heavy metals level in biological matrices of the exposed workers in different occupational settings revealed that developing countries are severely contaminated. Occupational settings from the Sialkot district, Pakistan exhibited elevated level of Cr in biological entities of the exposed workers. Review suggested that higher level of Cr exposure to the workers enhance the oxidative stress (reactive oxygen species (ROS) and hydroxyl (OH) radical generation) which may cause; cellular and molecular damage such as genotoxicity and chromosomal aberration formations, and carcinogenic effects. This review will help to understand the Cr contamination mechanisms and associated health implications in different occupational settings around the globe in general and particularly to Pakistan. This study will also assist occupational health and safety management authorities to devise or change the Cr recommended exposure limits (REL) for different occupational settings.

Eosinophilic airway disease in a patient with a negative skin prick test, but a positive patch test with platinum salts--implications for medical surveillance

We present the case of a 52-year-old woman with a topic dermatitis since adolescence who developed work-related hand eczema, cough and runny nose 12 years after she had started working as a laboratory technician at a precious metals refinery. While skin prick test with sodium hexachloroplatinate (SPTPt ) was negative, patch testing with ammonium tetrachloroplatinate was positive after 24, 48, 72, and 96 hr. Inhalation challenge with sodium hexachloroplatinate yielded cough, mild shortness of breath, and a maximal decrease of FEV1 of 8% from baseline 24 hr after the challenge. Significant increases of bronchial hyperresponsiveness, exhaled nitric monoxide and sputum eosinophils were documented after the challenge. We conclude that eosinophilic airway disease due to platinum salts may occur in SPTPt negative subjects. Both, patch testing and inhalation challenge with platinum salts should be considered in SPT negative subjects with occupational exposure to precious metal salts and work-related allergic symptoms.

The effects of chromium(VI) on the thioredoxin system: implications for redox regulation

Hexavalent chromium [Cr(VI)] compounds are highly redox active and have long been recognized as potent cytotoxins and carcinogens. The intracellular reduction of Cr(VI) generates reactive Cr intermediates, which are themselves strong oxidants, as well as superoxide, hydrogen peroxide, and hydroxyl radical. These probably contribute to the oxidative damage and effects on redox-sensitive transcription factors that have been reported. However, the identification of events that initiate these signaling changes has been elusive. More recent studies show that Cr(VI) causes irreversible inhibition of thioredoxin reductase (TrxR) and oxidation of thioredoxin (Trx) and peroxiredoxin (Prx). Mitochondrial Trx2/Prx3 are more sensitive to Cr(VI) treatment than cytosolic Trx1/Prx1, although both compartments show thiol oxidation with higher doses or longer treatments. Thiol redox proteomics demonstrate that Trx2, Prx3, and Trx1 are among the most sensitive proteins in cells to Cr(VI) treatment. Their oxidation could therefore represent initiating events that have widespread implications for protein thiol redox control and for multiple aspects of redox signaling. This review summarizes the effects of Cr(VI) on the TrxR/Trx system and how these events could influence a number of downstream redox signaling systems that are influenced by Cr(VI) exposure. Some of the signaling events discussed include the activation of apoptosis signal regulating kinase and MAP kinases (p38 and JNK) and the modulation of a number of redox-sensitive transcription factors including AP-1, NF-κB, p53, and Nrf2.

Exposure to particulate hexavalent chromium exacerbates allergic asthma pathology

Airborne hexavalent chromate, Cr(VI), has been identified by the Environmental Protection Agency as a possible health threat in urban areas, due to the carcinogenic potential of some of its forms. Particulate chromates are produced in many different industrial settings, with high levels of aerosolized forms historically documented. Along with an increased risk of lung cancer, a high incidence of allergic asthma has been reported in workers exposed to certain inhaled particulate Cr(VI) compounds. However, a direct causal association between Cr(VI) and allergic asthma has not been established. We recently showed that inhaled particulate Cr(VI) induces an innate neutrophilic inflammatory response in BALB/c mice. In the current studies we investigated how the inflammation induced by inhaled particulate Cr(VI) might alter the pathology of an allergic asthmatic response. We used a well-established mouse model of allergic asthma. Groups of ovalbumin protein (OVA)-primed mice were challenged either with OVA alone, or with a combination of OVA and particulate zinc chromate, and various parameters associated with asthmatic responses were measured. Co-exposure to particulate Cr(VI) and OVA mediated a mixed form of asthma in which both eosinophils and neutrophils are present in airways, tissue pathology is markedly exacerbated, and airway hyperresponsiveness is significantly increased. Taken together these findings suggest that inhalation of particulate forms of Cr(VI) may augment the severity of ongoing allergic asthma, as well as alter its phenotype. Such findings may have implications for asthmatics in settings in which airborne particulate Cr(VI) compounds are present at high levels.

Simultaneous analysis of the local and systemic immune responses in mice to study the occupational asthma mechanisms induced by chromium and platinum

As a result of industrial development, increased exposure to platinum and chromium compounds and the subsequent development of occupational asthma (OA) has been reported. Although specific IgE antibodies, an indicator of allergic asthma, against chromium and platinum have been detected in workers with OA, the immunopathological mechanisms involved in this disease are not fully understood. To better understand these complex mechanisms, the local and systemic immune responses were simultaneously analyzed in mice sensitized and challenged three, four, or five times with sodium hexachloroplatinate (Pt salt) and with potassium dichromate (Cr salt) via the respiratory route. Dinitrochlorobenzene (DNCB) and anhydride trimellitic (TMA) were included in this study as reference compounds that induce Th1 and Th2 responses respectively. All the compounds studied may provoke pulmonary sensitization. In the Pt salt-treated mice with a significant increase in local Th2 cytokine production, the increase in IgE and mucus production and in eosinophil number had a positive correlation with the number of challenges (r=0.942, 0.976, and 0.978 respectively), whereas in the Cr salt-treated mice with no local increase in Th2 cytokines, the increase in IgE production and eosinophil numbers had an inverse correlation with the number of challenges (r=-0.895 and -0.999 respectively). The Th2-dominated response induced by Pt salt was very close to that induced by TMA and may thrive after the fifth challenge, probably due to the constancy of the significant decrease in IFN-γ level in the spleens. The results of the present work may increase our understanding of the immunopathological mechanisms of OA induced by platinum and chromium, and emphasize the advantage of simultaneously analyzing local and systemic immune response when studying respiratory allergy.

[Occupational asthma caused by chromium and nickel]

We report the case of a 40-year-old woman who developed occupational asthma following exposure to chromium and nickel in the nickel-plating section of a metalworks company. Skin prick tests for specific antibodies proved positive for nickel chloride at a concentration of 1 mg/mL and negative for potassium dichromate. The specific bronchial provocation test confirmed the diagnosis of occupational asthma due to exposure to chromium and nickel. The patient presented a late positive reaction to nickel chloride (0.1 mg/mL) and an immediate positive reaction to a 10 mg/mL solution of potassium dichromate. These results indicate a dual response to nickel and chromium in this patient.

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.

Occupational asthma due to chromium and nickel salts

BACKGROUND

Exposure to chromium and nickel salts is a poorly characterized cause of occupational asthma.

METHODS

We describe four patients with work-related asthma due to metallic salts. Skin-prick tests to potassium dichromate and nickel sulfate were performed. The patients underwent methacholine inhalation tests and specific inhalation challenges (SIC) with both chromium and nickel salts.

RESULTS

Two patients showed positive skin-prick tests to potassium dichromate and nickel sulfate. All patients had bronchial hyperresponsiveness to methacholine, which increased 24 h after SIC with metallic salts. SIC with potassium dichromate elicited late asthmatic reactions (LAR) in two workers, one subject had an early asthmatic reaction (EAR), and another subject showed a dual asthmatic reaction (DAR). SIC with nickel sulfate induced a DAR in one subject and a late asthmatic reaction in another.

CONCLUSIONS

Chromium and nickel salts can give rise to occupational asthma in exposed workers. The underlying mechanism may be IgE-mediated in some cases.

Occupational airway sensitizers: an overview on the respective literature

BACKGROUND

Worldwide, there is rigorous scientific activity concerning the further development of work safety regulations involving airway-sensitizing substances. Technical directives on hazardous substances are enforced in several countries and are being continuously updated. The European Union has established a code for several occupational substances, now labeled R 42 ("may cause sensitization by inhalation").

METHODS

We present an overview of the literature dealing with allergic occupational asthma. The literature was selected according to criteria of study design and diagnostic test methods. Approximately 300 publications were reviewed including both epidemiological studies and individual case reports.

RESULTS

Airway sensitizers are systematically arranged and separately listed according to chemicals and their origin from animals, plants, and microorganisms. The clinical data as well as threshold limit values (TLV) and R 42 labeling of 250 airway-sensitizing substances are presented.

CONCLUSIONS

The most common sensitizing substances causing occupational asthma were dust of cereal flours, enzymes, natural rubber latex, laboratory animals as well as low molecular substances such as isocyanates and acid anhydrides.

Assessment of the sensitization potential of five metal salts in the murine local lymph node assay

The murine local lymph node assay (LLNA) has been proposed as a predictive test for the identification of sensitizing agents. We used this test to compare the sensitization potential of NiSO4, K2Cr2O7, CoCl2, Na2PtCl6 and BeSO4, salts of metals which have all been associated with allergic contact dermatitis and either bronchial asthma orinterstitial lung disease, by either humoral or cell-mediated allergic mechanisms. BALB/c mice (n = 3 per concentration studied, three concentrations studied per metal) received three daily applications of the metal salt (in DMSO) on the dorsum of both ears. On the fourth day the draining auricular lymph nodes were removed and the incorporation of [3H]-thymidine in the lymphocytes in culture was compared to that of concurrent vehicle-treated control mice, thus enabling to derive a stimulation index (SI), indicative of immunological sensitization potential. Each experiment was performed three times. Oxazolone and toluene diisocyanate, chosen as positive controls, yielded strongly positive SI values (> 20 and > 30 respectively). Na2PtCl6 (SI 2.6 +/- 1.0 at 2.5%), CoCl2 (SI 2.8 +/- 0.5 at 5%) and possibly also K2Cr2O7 (SI 2.1 +/- 1.2 at 0.5%) were positive in the LLNA, whereas NiSO4 (SI 0.9 +/- 0.2 at 5%) and BeSO4 (SI 1.3 +/- 0.6 at 4%) were negative. Although our results are still limited by the fact that only one mice strain was tested, they indicate that there is no strict relationship between the sensitization potential of metal salts, as evaluated in the murine LLNA, and their potential to cause either respiratory or dermal allergic disease. Consequently, caution should be exercised before proposing the murine LLNA as a valid test to predict the sensitization potential of low molecular weight chemicals.

How to confirm occupational asthma

A methodological overview is provided on the important question of how to confirm occupational asthma in routine work. Recent knowledge gained in immunology and occupational allergy has been utilized, supplemented by an overview of recent publications on the diagnosis and pathophysiology of occupational asthma. The aim of the paper is to facilitate decision making for an investigator dealing with individual cases of occupational asthma. Moreover, by presenting stepping-stones in the diagnostic cascade, the author hopes to encourage the less experienced to conduct a comprehensive and cause-oriented diagnostic procedure. Methods which are being worked on at present (standardization) are discussed in more detail. Finally, the research goals in the understanding, confirmation, and prevention of occupational asthma are listed.