Silica is a naturally occurring compound found extensively in our environment. It’s composed of silicon and oxygen, and remarkably, it exists in various forms, all sharing the same chemical makeup but differing in their structural arrangements. Broadly, silica is categorized into two primary types: crystalline silica and amorphous silica (also known as non-crystalline silica). Quartz stands out as the most prevalent form of crystalline silica, with other, less common crystalline types also existing.
Silica compounds are ubiquitous, present in rocks, sand, clay, soil, air, and water. This versatile compound is also a key ingredient in numerous commercial products we use daily. You’ll find silica in bricks, glass, ceramics, plaster, granite, concrete, and even in cleansers, skin care products, and talcum powder. Certain forms of amorphous silica are utilized as food additives, in food packaging, toothpaste, and cosmetic products.
Silica Exposure: How Does it Happen?
For the general population, exposure to silica is a part of everyday life, occurring through the air we breathe, certain types of indoor dust (like that from concrete), our food and water, soil, and various consumer products. Airborne exposure is the primary concern regarding silica. However, it’s important to note that most silica particles in the air encountered by the public are too large (non-respirable) to penetrate deep into the lungs and cause harm.
The situation is different for workers in specific industries. They face significantly higher levels of silica exposure compared to the general public. Activities such as blasting, cutting, drilling, or grinding materials that contain silica can generate small particles of silica dust that are respirable. This poses a serious health risk, particularly for those working with materials containing crystalline silica in sectors like construction, mining, sandblasting, and porcelain manufacturing. Occupational exposure to crystalline silica is a recognized and significant workplace hazard.
Health Implications of Crystalline Silica
It’s important to emphasize that exposure to crystalline silica at levels typically found in the general environment is not associated with known health effects.
Extensive research focusing on workers has investigated the potential link between crystalline silica exposure and adverse health outcomes. These studies have consistently shown that prolonged inhalation of small crystalline silica particles over years can lead to silicosis, a severe and irreversible lung disease. Crystalline silica is uniquely identified as the cause of silicosis. Furthermore, research in occupational settings has linked silica exposure to chronic obstructive pulmonary disease (COPD), lung cancer, kidney problems, autoimmune diseases, and an increased susceptibility to tuberculosis.
Health issues stemming from crystalline or amorphous silica are exceedingly rare among the general public. These health concerns primarily arise in workers who inhale silica dust in their workplaces.
Health Implications of Amorphous Silica
Currently, there are no established health effects linked to exposure to amorphous silica at the levels present in the environment or in everyday commercial products like food additives, food wrappings, toothpaste, and cosmetics.
While some reports suggest that amorphous silica might contribute to respiratory issues in workers (though not silicosis), studies involving laboratory animals indicate that, although breathing amorphous silica can cause lung inflammation and injury, it is considered less hazardous than crystalline silica.
Silica Exposure and Children
It is unlikely that children in developed countries would experience sufficient crystalline silica exposure to be at risk of silica-related diseases under normal circumstances. However, if children were exposed to high concentrations of small crystalline silica particles, potentially through child labor in developing countries, they would likely face similar health risks as adults. If you are concerned about your child’s potential exposure, consulting a doctor or nurse is advisable.
Crystalline Silica and Cancer Risk
Federal and international health agencies have concluded that inhaling respirable crystalline silica particles – those small enough to reach the lungs – can cause lung cancer. The Department of Health and Human Services and the International Agency for Research on Cancer classify respirable crystalline silica as a known human carcinogen (a substance that can cause cancer).
These conclusions are drawn from studies on workers demonstrating that long-term inhalation of respirable crystalline silica particles increases the risk of developing lung cancer. It’s crucial to note that the levels of these small particles in occupational settings are significantly higher than those typically found in the general environment.
Amorphous Silica and Cancer Risk
Studies examining amorphous silica exposure in workers and laboratory animals have not found evidence of cancer. Consequently, federal and international agencies have not reached any conclusions regarding the potential of amorphous silica to cause cancer.
Medical Testing for Silica Exposure
Currently, there are no specific medical tests to determine if you have been exposed to silica.
Protecting Yourself and Your Family from Silica
Typical exposures to large particles of crystalline or amorphous silica encountered by the general public are not known to cause health problems in individuals without pre-existing lung conditions like asthma. Therefore, for most people, taking special precautions to avoid silica in daily life or when using products containing silica is unnecessary. However, if you engage in hobbies or activities that generate fine dust by grinding or cutting silica-containing materials, wearing protective equipment like a particle mask is recommended. Workers exposed to silica should take care to avoid bringing dust home on their clothing.
Workers who anticipate prolonged exposure to respirable crystalline silica should discuss safety measures with their supervisors or employers. The National Institute for Occupational Safety and Health (NIOSH) provides valuable information on workplace silica safety https://www.cdc.gov/niosh/topics/silica/.
For Further Information
For more information, you can contact CDC-INFO at 1-800-232-4636, or submit your inquiries online at https://wwwn.cdc.gov/dcs/ContactUs/Form.
You can also access the ATSDR’s Toxicological Profile for Silica: “https://www.atsdr.cdc.gov/TSP/ToxProfiles/ToxProfiles.aspx?id=1483&tid=290”
Visit the ATSDR’s Toxic Substances Portal: https://wwwn.cdc.gov/TSP/index.aspx
Find and contact your ATSDR Regional Representative at https://www.atsdr.cdc.gov/DRO/dro_org.html
