Silica: A lung carcinogen

Abstract

Silica has been known to cause silicosis for centuries, and evidence that silica causes lung cancer has accumulated over the last several decades. This article highlights 3 important developments in understanding the health effects of silica and preventing illness and death from silica exposure at work. First, recent epidemiologic studies have provided new information about silica and lung cancer. This includes detailed exposure-response data, thereby enabling the quantitative risk assessment needed for regulation. New studies have also shown that excess lung mortality occurs in silica-exposed workers who do not have silicosis and who do not smoke. Second, the US Occupational Safety and Health Administration has recently proposed a new rule lowering the permissible occupational limit for silica. There are approximately 2 million US workers currently exposed to silica. Risk assessments estimate that lowering occupational exposure limits from the current to the proposed standard will reduce silicosis and lung cancer mortality to approximately one-half of the rates predicted under the current standard. Third, low-dose computed tomography scanning has now been proven to be an effective screening method for lung cancer. For clinicians, asking about occupational history to determine if silica exposure has occurred is recommended. If such exposure has occurred, extra attention might be given to the early detection of silicosis and lung cancer, as well as extra emphasis on quitting smoking.

Role of p53–fibrinolytic system cross-talk in the regulation of quartz-induced lung injury

“…Historically, this has been estimated to be in millions of people on an annual basis (US Department of Health and Human Services Progress Review, 2010; US Department of Labor, 2010; Steenland and Ward, 2014). Lung epithelial cells are constantly exposed to dust particles.…”

“…Epidemiological studies indicate that chronic silicosis is most common in stone dressers, quarry workers, foundry workers, gold and black miners (Healy et al, 2014;Verma et al, 2011;Zhang et al, 2010;Ehrlich et al, 2011;Nelson et al, 2010). The Centers for Disease Control and Prevention (CDC) have recently reported that the incidence and mortality from silicosis are on a rise due to advanced mining techniques used to extract materials deeply embedded in quartz substrate and with increased efficiency that enriches the overall silica content in respirable dust exposure (Centers for Disease Control and Prevention (CDC), 2005; Steenland and Ward, 2014).…”

Selenium and exposure to fibrogenic mineral dust: A mini-review

“…Silicosis may develop in some cases together with a variety of diseases including tuberculosis (Xia et al, 2014); CWP and autoimmune diseases (Maeda et al, 2010). Silica exposure is still prevalent in low and middle income countries, and developed countries also are not immune to new silica exposure (Steenland and Ward, 2014).…”

Extended follow-up of lung cancer and non-malignant respiratory disease mortality among California diatomaceous earth workers

“…Crystalline silica is considered a potentially hazardous exposure to an estimated tens of millions workers worldwide 1. Respiratory exposures to crystalline silica result from drilling, mining and other activities that process silica-containing soil, sand, granite and other minerals in numerous industries.…”