September 20, 2018 The Health Consequences of Occupational Silica Exposure

Has silica become the new asbestos?

What is silica?

Silica, a mineral compound which naturally occurs in sand and stone, is the element with the highest prevalence in the crust of the earth, making up over 60% of it. Quartz is the most common form of silica. While harmless when left undisturbed, silica – scientifically known as silicon dioxide – turns into a real health hazard if it becomes airborne. Numerous health agencies from all around the globe have classified silica as a known human carcinogen. Accordingly, exposure to respirable silica dust, which takes place mostly via inhalation, can lead to multiple serious diseases. The ingestion of silica particles is also dangerous, as this is another route via which the agent can easily reach the respiratory system.

In over 95% of cases, exposure happens in the workplace, preponderantly in the mining and construction industries. More than 1,000 people lose their lives to diseases caused by silica dust exposure every year in the UK, whereas half a million others are exposed on the job annually. Although there is a permissible limit of silica exposure effective for high-risk occupational groups in the country (0.1 milligrams of silica particles per cubic meter), the likelihood of developing a disease remains. Indeed, medical studies have found that exposure to 0.1 milligrams of silica particles per cubic meter over 15 years increases the risk of silicosis significantly. Furthermore, 30 years of exposure to the same air concentration of respirable silica dust heightens the chances of getting silicosis in the future by 25%.

The diseases caused by silica dust

Naturally, the most susceptible organs are the lungs. Similarly to asbestos fibers, silica particles are extremely tiny – one hundred times smaller than a grain of sand – which facilitates their access to the lungs, from where they cannot be completely expelled. Consequently, they will lodge in lung tissue, producing increasingly severe inflammation and scarring which may eventually result in a disease or in the growth of a malignant tumor. The following diseases may ensue following occupational silica exposure:

• Silicosis. This is a pulmonary disease which greatly hinders breathing capacity and lung function by causing tissue scarring and fluid buildup. It may appear as early as several months after a person came in contact with airborne silica (acute silicosis) or as late as 20 years following exposure (chronic silicosis). Symptoms include wheezing, a persisting cough, shortness of breath, fatigue, chest pain, and loss of appetite. Even though the disease has no cure at the moment, it can be successfully kept under control with the aid of medication and, if necessary, oxygen therapy. Suffering from silicosis also makes you more prone to tuberculosis, another lung disease.
• Lung cancer. Exposure to silica dust may also result in lung cancer, as particles are highly irritating and can trigger the development of a malignant tumor over time. Unfortunately, most individuals who come to suffer from lung cancer as a consequence of silica exposure only discover their illness after it has reached advanced stages, which usually entails a poor prognosis.
• COPD. Chronic obstructive pulmonary disease, which refers to emphysema and chronic bronchitis, is another health effect of workplace silica exposure. Like silicosis, it affects airflow from the lungs and thereby makes breathing difficult. It is also irreversible and implies a high risk of more severe diseases, such as lung cancer and heart disease. Tobacco smoking is a major contributing factor and, along with silica exposure, increases the susceptibility to COPD tremendously.
• Autoimmune diseases. Scleroderma, lupus, and vasculitis have been correlated with exposure to silica dust, too. While additional medical evidence is required to support these causal relationships, existent research indicates a possible association.
• Kidney disease. As in the case of autoimmune diseases, more proof is necessary to sustain the connection between silica exposure and kidney disease, but a link has already been suggested by medical researchers.

Miners are at great risk

Mining and quarry work imply a high risk of silica exposure, as these activities inevitably release toxic dust in the air. In the absence of proper equipment such as respirators, workers will breathe in significant amounts of silica dust, which may ultimately wreak havoc on the health of their lungs. Two of the most dangerous mining operations in this regard are cutting and drilling through granite or sandstone, since these types of rock contain a great concentration of silica. Contrary to popular belief, working outside is as menacing as doing your job inside and performing short work tasks will not spare you the risk of inhaling silica dust either.

While the use of fan-powered dust collectors (also known as flooded-bed scrubbers) on continuous miners may seem like a positive change at first glance, it is actually the opposite. The density of the filter media in scrubber filter panels, which has undergone substantial reduction to promote airflow over recent decades, now allows more silica particles and other hazardous dusts to infiltrate occupational settings, thereby endangering the health of individuals who work on mining sites. While filter media in the original fan-powered dust collectors was made up of 40 layers of stainless steel wire mesh, the one employed today consists of only 20 layers.

Can exposure be minimized?

If you are working with silica on a regular basis, it is essential to wear the protective equipment you were provided with at all times, even after the operation which released dust in the air is completed, as silica particles tend to linger in the atmosphere. It is also recommended that you and your co-workers ensure your employer is complying with the permissible silica exposure limit. Should you find out the limit is exceeded, please do not hesitate to take action by notifying the appropriate authorities, as your health might be at stake.

About the author
Gregory A. Cade is a legal professional with over 20 years of experience in the fields of environmental and asbestos law. Together with his firm, Environmental Litigation Group, they have processed over 200.000 asbestos claims and raised more than $1 billion. He is the recipient of numerous awards, such as Alabama’s 2005 Top 40 Under 40, as well as a member of several renowned legal associations, such as The American Bar Association and The National Registry of Environmental Professionals.

Subscribe to Industry Today