- By Shaniqua Williams
Also known as silicon dioxide, silica is a mineral component which occurs naturally in sand and stone, oftentimes as quartz. While the mere presence of silica in these two raw materials is not a menace per se, disturbing products which contain sand or stone will create a health hazard, since doing so is bound to release a considerable amount of dust in the air. Similarly to asbestos, silica is dangerous only when it becomes airborne. In 1996, respirable crystalline silica in the form of quartz and cristobalite dust was classified as a known human carcinogen by the International Agency for Research on Cancer (IARC). The most common affliction which may result from inhaling silica dust is silicosis, a harrowing lung disease which increasingly reduces breathing capacity, thereby taking a heavy toll on quality of life. Nonetheless, silica exposure is also responsible for kidney disease, COPD, lung cancer, as well as various autoimmune diseases such as lupus and scleroderma.
Due to their accessibility and practicality, sand and stone have been massively exploited as natural resources ever since ancient times, including by Egyptians, who often came to suffer from silicosis as a consequence. The disease was also widespread among Italian artisans during the Renaissance, as physician Bernardo Ramazzini noted. Nowadays, silica exposure concerns primarily the construction industry, since employees handle products made of stone and sand - such as brick, concrete, drywall, or ceramic tiles - on a regular basis. However, while construction workers are at highest risk, there are unfortunately plenty of other occupational groups which may be affected by silica dust as well. Because track ballast usually consists in granite and limestone, railroad workers are also subjected to silica exposure on the job.
Since silica resides in the crushed stone which makes up the track ballast, any activity involving it will inevitably generate harmful dust, to a greater or lesser extent. Granite, which is the go-to rock when it comes to track ballast, may contain up to 45% silica. Although the other types of rock which might be present in track ballast, namely limestone and basalt, have lower concentrations of silica (typically less than 5%), their use is only occasional, as they are not the most suitable option in this regard.
The following activities place railroad workers at high risk for silica exposure when they are carried out without wearing protective equipment:
As for specific equipment, railroad workers who operate the machinery below are likely to inhale significant amounts of silica dust:
Exposure to silica dust in the rail industry commonly leads to silicosis, a life-threatening pulmonary disease which gradually weakens the lungs, hindering breathing capacity to a tremendous extent over time. Up to 7,300 new cases are diagnosed every year in the U.S. and, since there is no known cure for the disease, the majority of people suffering from silicosis will lose their life to respiratory failure.
Because silica particles are extremely tiny, being even smaller than fine grains of sand, they will inevitably remain inside the lungs after inhalation. Should silicosis develop, the toxic particles will slowly cause pleural effusion (fluid buildup) and fibrosis (tissue scarring) until the proper onset of the disease. Depending on the severity of exposure, silicosis may ensue within a few months to 20 years following the inhalation of silica dust. Current or former railroad workers who experience some of the following symptoms may have silicosis:
In addition to reducing the level of oxygen in the blood, silicosis can also affect the right side of the heart, which may lead to cor pulmonale, a very serious and frequently fatal pulmonary heart disease. People with silicosis are also susceptible to developing tuberculosis and chronic bronchitis as a result of the extensive damage which took over their lungs. Although silicosis is undoubtedly the most widespread health issue stemming from silica exposure, there are other diseases which may afflict railroad workers who regularly handle track ballast, such as:
Silicosis is 100% preventable. If you are a railroad worker, we strongly encourage you to make sure your employer provides you with adequate equipment to wear on the job, such as a N95, R95, or P95 respirator, as using protective gear is the most effective way of preventing silicosis, as well as other serious diseases. You should wear your respirator permanently while working with track ballast and also afterwards, since silica dust will linger in the air for a good time following the disturbance of crushed rock. Finally, to avoid exposing your family and other people to silica, it is imperative to change your clothes at the end of the day. Your employer has the legal obligation to ensure that safety regulations are properly enforced in the workplace at all times.
Periodically monitoring the air concentration of silica is vital to ensuring a safe, hazard-free environment for your workers. Our highly experienced industrial hygienists have been performing silica testing services for a vast range of companies within the last 25 years using the latest technology. By virtue of NIOSH method 7500 by X-ray diffraction, they can now detect and measure the most common forms of crystalline silica - quartz, cristobalite, and tridymite - with high accuracy. If you are a railroad employer, please feel free to contact us and our certified experts will gladly assist you.Call 205.328.9200