Silicosis is a progressive interstitial lung disease, characterized by shortness of breath, cough, fever and bluish skin; it can present in three different forms: acute, accelerated and chronic. (1) It is caused by the lung tissue reaction to the inhalation of silica and occurs most commonly as an occupational disease of people working in the quarrying, manufacturing and building construction industries. Exposure to large amounts of free silica can go unnoticed because silica is odourless, non-irritant and does not cause any immediate health effects. As silicosis is incurable, clinical management includes removing the worker from the industry and giving symptomatic treatment. Public health goals are to detect early cases through monitoring of currently and formerly exposed workers, to establish surveillance programmes, to slow progression and to reduce disability. (2) In 1995, the World Health Organization and the International Labour Organization began a public awareness and prevention campaign to eliminate silicosis from the world by 2030. (3) Several countries--Brazil, Chile, China, Indonesia, Malaysia, Mexico, Poland, South Africa, Thailand, Turkey, Ukraine, the Bolivarian Republic of Venezuela and Viet Nam--have established national programmes for the elimination of silicosis. (3) However, in many low- to middle-income countries, including India, silicosis continues to be an occupational health hazard. India has a large mining industry, concentrated in the states of Chhattisgarh, Jharkhand, Orissa and West Bengal. In 1999, the Indian Council of Medical Research reported that around 3.0 million workers are at high risk of exposure to silica; of these, 1.7 million work in mining or quarrying activities, 0.6 million in the manufacture of non-metallic products (such as refractory products, structural clay, glass and mica) and 0.7 million in the metals industry. (4) There are also around 5.3 million construction workers at risk of silica exposure. (4) Due to variations in silica concentrations and duration of exposure in the work environment the reported prevalence of silicosis in India ranges widely--from 3.5% among 1977 workers in an ordnance factory to 54.6% in 593 workers in the slate-pencil industry. (5,6) The main challenge of eliminating silicosis in India is in the informal, unregulated sectors of industry which do not fall under the control of statutory tools such as the Factory Act of India (1948). (7) This Act mandates a well ventilated working environment, provisions for protection from dust, reduction of overcrowding and provision of basic occupational health care. Silicosis-affected workers in the informal sector are not entitled to statutory protection, which would remove them from the hazardous environment, or to compensation, which would enable them to leave work. Continued exposure makes it difficult for physicians to manage the disease. Furthermore, most primary-care physicians in India are not trained to manage occupational health diseases. Among the clinical complications of silicosis is tuberculosis (called silicotuberculosis), a disease which is still a major public health concern in low- and middle-income countries. (8) Chronic exposure to silica increases workers' risk of tuberculosis infection and aggravates pre-existing pulmonary tuberculosis. (9-11) Differential diagnosis is a challenge. Although treatable, tuberculosis in silicosis patients may go undiagnosed because cough, wheeze, expectoration, dyspnoea and vague chest pains are symptoms common to both diseases. Interpretation of the chest X-ray film of patients with silicosis is difficult due to the superimposition of silicotic nodules and tuberculous infiltrations. Mycobacterium tuberculosis bacilli may not be recovered from the sputum of silicotuberculosis patients because silicotic fibrosis prevents the discharge of tubercle bacilli into the sputum. (8) Acid-fast bacilli, if cultured, are mainly non-tuberculous mycobacteria. …
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May 25, 2017
Jorge Castro + 1
Open Access
