Safety Awareness: What is Crystalline Silica?

General industry workers face many on-the-job hazards, ranging from falls, crushing injuries, and electrical dangers to chemical exposure. In the midst of these risks, a subtle but serious threat exists: crystalline silica.

This blog post aims to raise awareness among workers exposed to crystalline silica. We will cover its definition, symptoms, associated health risks, and the steps you can take to protect yourself from exposure.

WHAT IS SILICA?

Silicon dioxide (SiO2), commonly known as silica, is a mineral that constitutes 59% of the Earth's crust by mass. It can be found in various natural sources such as soil, sand, granite, and concrete, and over 95% of known rock types on our planet.

Silica exists in two primary forms: crystalline and non-crystalline, also known as amorphous. Among these, crystalline silica is the more hazardous variety. It is highly valued for industrial and manufacturing applications due to its hardness, chemical inertness, and high melting point. 

Quartz is the most prevalent form of crystalline silica, although it can also manifest as cristobalite and tridymite.

In contrast, non-crystalline silica is present in materials like silica gel, silicone, and silicon carbide. These substances pose significantly fewer health risks compared to their crystalline counterparts.

IS SILICA BAD FOR YOU?

In its natural state, silica is not bad for you. Silica present in rocks, soil, and sand poses no harm. In fact, it occurs naturally in soil and subsequently in various vegetables and grains we consume. 

When we ingest foods containing silica, it becomes a part of our bodily tissues. You may even encounter it as an ingredient in dietary supplements or food additives.

The issue arises when we engage in activities involving materials that contain crystalline silica. Once crystalline silica is ground into fine dust, it becomes airborne and attains a size small enough for inhalation, approximately 100 times smaller than natural sand particles. 

This form is known as respirable crystalline silica (RCS), and it represents a health hazard.

WHY IS SILICA DUST BAD FOR YOUR HEALTH?

Inhaling silica dust can expose you to a wide range of respiratory ailments by introducing minuscule particles deep into your lungs. 

Additionally, it can trigger an immune response that leads to harm in various tissues or organs. Consequently, there is some supporting evidence linking exposure to silica dust with conditions such as kidney failure, rheumatoid arthritis, and other autoimmune disorders.

However, the association between silica dust and lung diseases, particularly silicosis, has been extensively researched and is better understood.

WHAT IS SILICOSIS?

Silicosis stands out as the most prevalent ailment stemming from exposure to silicate materials. Our understanding of silicosis dates to centuries ago. 

In the 1700s, an early medical scholar observed that when he conducted postmortem examinations on stonecutters, their lungs contained significant quantities of what he referred to as "sand." 

Contemporary pathologists describe how silicosis can render lungs extremely firm, to the point where they resist being cut even with a scalpel. 

Silicosis is indeed as severe as it appears. It can develop after only a few months of substantial exposure, and its progression is relentless. The lungs react to silica dust by forming scar tissue, impairing the ability to absorb an adequate amount of oxygen. 

Unfortunately, there is currently no cure for silicosis, and it can result in disability and, in some cases, death. 

SYMPTOMS OF SILICOSIS

The symptoms of silicosis can vary depending on the severity of the condition, but common symptoms include: 

• Cough: Persistent coughing is often one of the earliest symptoms of silicosis.
• Shortness of Breath: As the disease progresses, individuals may experience increasing difficulty in breathing, especially during physical activity.
• Wheezing: Wheezing or a whistling sound when breathing may occur.
• Chest Pain: Some individuals with silicosis may experience chest discomfort or pain.
• Fatigue: Chronic fatigue and a general feeling of weakness may develop.
• Weight Loss: Unintentional weight loss can be a symptom of advanced silicosis.
• Fever: In some cases, fever may accompany silicosis, especially if there is an associated lung infection. 

It's important to note that the severity and progression of silicosis can vary widely among individuals. In advanced stages, silicosis can lead to significant lung damage and increase the risk of other respiratory conditions, including tuberculosis and lung cancer. 

Anyone experiencing these symptoms and who has been exposed to silica dust should seek medical attention promptly. Preventive measures and early detection are crucial for managing silicosis effectively. 

CAN SILICA CAUSE CANCER?

Extensive research has prompted numerous international health organizations to categorize crystalline silica as a confirmed human carcinogen. There is compelling evidence linking silicate exposure to an elevated risk of developing lung cancer.

Moreover, inhaling respirable crystalline silica can also result in chronic obstructive pulmonary disease (COPD), heighten the susceptibility to contracting tuberculosis, and is linked to various other severe lung ailments. 

RESPIRATORY DISEASES CAUSED BY SILICA

Respiratory diseases caused by silica exposure primarily include:

• Silicosis
• Lung Cancer
• Chronic Obstructive Pulmonary Disease (COPD) 
• Tuberculosis (TB) 
• Autoimmune Diseases 

WHERE DOES SILICA COME FROM?

The production of respirable crystalline silica occurs when materials containing quartz, cristobalite, tridymite, or other crystalline silica forms are cut, chipped, ground, drilled, or crushed. 

Given that nearly all substances derived from the Earth's crust contain crystalline silica, this presents a multitude of possibilities for generating silica dust. 

WHO IS AT RISK FOR SILICATE EXPOSURE? 

According to the Occupational Safety and Health Administration (OSHA), approximately 2.3 million American workers encounter crystalline silica exposure during their work. In today's context, most of these workers (estimated at 80 to 90%) belong to the construction industry. Nevertheless, individuals in other sectors, such as maritime, manufacturing, and hydraulic fracturing, also face this exposure.

However, it's important to note that not all these workers share the same level of risk when it comes to exposure to silica dust. Specific job roles carry a higher risk, including tasks such as:

• Abbasive blasting (i.e., sandblasting)
• Underground Mining
• Tunneling
• Quarry work
• Stonecutting
• Foundry work
• Stoneware clay (i.e., ceramics and pottery) production
• Glass production
• Cement, concrete, asphalt, and brick production 

Approximately 100,000 workers in the United States are categorized as being at high risk. 

TREATMENT FOR SILICOSIS 

Unfortunately, there is no cure for silicosis, as the lung damage caused by silica exposure is typically irreversible. However, treatment aims to manage symptoms, slow disease progression, and address complications. Here are some treatment and management approaches for silicosis:

• Symptom Management: Medications, such as bronchodilators, may be prescribed to help alleviate breathing difficulties and reduce coughing and wheezing.
• Oxygen Therapy: For individuals with severe breathing problems, supplemental oxygen therapy may be necessary to ensure sufficient oxygen levels in the blood.
• Pulmonary Rehabilitation: A structured pulmonary rehabilitation program can help improve lung function, enhance exercise capacity, and provide education on managing the disease.
• Avoid Further Exposure: It's crucial to eliminate ongoing exposure to silica dust to prevent the worsening of symptoms and further lung damage. This may involve changing jobs or implementing strict workplace safety measures.
• Vaccination: Vaccination against respiratory infections, including influenza and pneumococcal pneumonia, can help reduce the risk of complications.
• Treatment of Complications: If complications such as tuberculosis or lung infections occur, prompt treatment with appropriate medications is essential.
• Lung Transplant: In severe cases of silicosis with advanced lung damage and respiratory failure, a lung transplant may be considered as a last resort. However, lung transplants are complex procedures with significant risks and limited availability. 

Moreover, regular health check-ups and early detection are also vital for individuals with a history of silica exposure. 

Prevention remains the most effective approach to dealing with silicosis. Strict workplace safety measures, which we go into detail below, can help prevent silicosis in at-risk industries. 

HOW TO AVOID SILICA EXPOSURE 

Employers can effectively reduce exposure to silica dust by opting for safer alternatives to crystalline silica materials whenever feasible.

When working with crystalline silica becomes necessary, the most efficient approach is to manage silica dust directly at its source. Water spraying is often the optimal choice for dust control. 

It involves directing a fine mist precisely at the point where cutting and grinding take place to prevent silica dust from becoming airborne. Increasing the volume of water used enhances dust control effectiveness.

In cases where using water is impractical, alternative methods such as vacuuming or ventilation should be employed to regulate the presence of silica dust in the air. 

Additionally, it's advisable to isolate the dust-producing activity from nearby workers, potentially using an enclosure or tent. 

However, this approach places the worker(s) inside the enclosure at an increased exposure risk, necessitating the combination of active ventilation and a filter sock to capture silica dust. 

Ultimately, if controlling silica dust at the source proves challenging, respirators can be employed to safeguard workers from inhaling it.

WHAT ARE OSHA'S SILICA STANDARDS? 

In 2016, OSHA revised its silica standards to align with contemporary scientific knowledge regarding silica dust exposure and to mandate the utilization of engineering controls, including the dust control methods mentioned earlier.

The comprehensive silica standards can be found in 29 CFR 1910.1053 for general industry and maritime workplaces and in § 1926.1153 for construction industry workplaces.

WHAT DO THE NEW OSHA SILICA STANDARDS REQUIRE? 

As a component of these revisions, OSHA established new permissible exposure limits (PELs) for silica. These updated PELs are consistent across the board and apply to general industry, maritime, and construction workplaces alike. 

In the past, the requirements were considerably more stringent for general industry, while maritime and construction workers had comparatively fewer protective measures in place. 

Employers are now required to: 

• Limit access to areas where you can be exposed above PELs.
• Restrict housekeeping practices that expose workers to silica.
• Take silica safety precautions that keep silica dust at or below PELs. Employers must try to solve the problem with engineering controls and work practices first – these are the dust control methods we described above.
• Provide respirators if exposure levels remain too high after dust control methods.
• Create a written exposure control plan.
• Offer medical exams every 3 years, including chest X-rays and lung function tests, to certain high-risk workers.
• Keep records of workers' silica exposure and medical exam results.
• Train workers on the health effects of silica exposure, what workplace tasks cause exposure, and how to protect themselves.

OSHA anticipates that the implementation of the new regulations, with a particular emphasis on engineering control mandates, will result in the prevention of approximately 600 fatalities annually, along with over 900 newly reported cases of silicosis.

HOW ARE SILICA MONITORING STANDARDS DIFFERENT FOR CONSTRUCTION THAN OTHER INDUSTRIES? 

Apart from the requirements mentioned earlier, employers operating under maritime and general industry standards are obligated to conduct exposure assessments. This entails the collection of air samples for silica, which must then be analyzed by accredited laboratories to ensure that the concentrations remain within the permissible exposure limits (PELs).

For construction industry employers, OSHA has established more flexible compliance options, acknowledging the practical challenges associated with exposure monitoring, especially in outdoor settings where PELs can fluctuate rapidly. OSHA offers a predefined list of common construction tasks that generate significant respirable crystalline silica (RCS) exposure, known as Table 1. 

This table specifies the engineering controls, work practices, and respiratory protection necessary to effectively safeguard workers during the execution of each task.

Construction employers who fully and correctly implement the measures outlined in Table 1 are exempt from the obligation to measure exposure levels. Otherwise, they must resort to air monitoring and laboratory assessments, like the requirements imposed on maritime and general industry employers.

GET OSHA-AUTHORIZED SILICA TRAINING ONLINE 

Meeting OSHA's silica standards training requirements can be made easy and budget-friendly through an online course. 

Any worker who may encounter respirable crystalline silica (RCS) exposure is mandated to undergo OSHA's mandatory training, and they can easily fulfill this requirement from any location with internet access by enrolling through OSHA.com. 

As a trusted OSHA-authorized training provider, we offer a full catalog of construction and general industry OSHA courses, including a Respirable Crystalline Silica Safety Awareness Course. Enroll now to meet your requirements in no time!