Initial Publication Date: December 13, 2012

Silicon, Silicates and Silicosis

Author: Austin Smilovic

This case study is part of a collection of pages developed by students in the 2012 introductory-level Geology and Human Health course in the Department of Earth Sciences, Montana State University. Learn more about this project.

If you are exposed to dust in the atmosphere from natural or human-caused sources, you may be at risk for permanent health damage due to silicosis. To find out more about the risks, health impacts, and ways to protect yourself please read on.

Introduction

Silicon and oxygen are by far the most abundant elements available in the Earth's crust. Minerals that have any sort of combination of silicon and oxygen are referred to as silicates and have the highest concentration in the Earth's surface. In fact, according to my Earth System Science class, silicates make up about 90% of Earth's crust mass. With that being said, if you are outdoors, you will most likely engage or cross paths with a silicate mineral in the duration of your time spent outside. So why is the placement and usage of silicate minerals important to understand? Well, it's simple, if your only interaction with silicates are in an observational sense then there is nothing to be worried about. However, if you're a person like me who works in an industry where silicate mineral material is a bi-product that cannot be avoided, it's crucial to be totally knowledgeable on when and how, you are being effected. Working at a job site where mineral exploration is the goal, I am constantly being exposed to conditions where silicosis should be a worry. I work in "mine country" by Radersburg where the terrain is flat with large hills and steep valleys. It forms the best conditions for silicate-filled dust to blow around and lead to the development of silicosis. If one does not take the proper precautionary steps needed to preserve the longevity of your life, the terrain and climate can be your biggest enemy. In Radersburg the winds always tend to be at higher speeds then average, making the wind a factor of concern, but more than anything, one's work habit and safety precautions are the biggest contributors to silicosis. Some things are completely unavoidable while working in this field, unfortunately,wind and dust happen to be some of them.

How does Silicon turn to Silicosis?

Silicon (Si) is a naturally occurring element that can cause significant health hazards depending on how and when you become involved with the element. Silicon is heavily used in the industrial market and is therefore commercially mined for this purpose. Its uses commercially are for: building use of clay, stone and silica sand. It also has uses in ceramics, porcelain, stucco, gravel and concrete. The list for how Si can be manipulated can go on forever, what is important to understand is when you are in danger from its adverse health affects. Silicon becomes dangerous when it is airborne and is capable of getting into the air paths of the human body. This happens anytime any sort of the following jobs take place: when manufacturing glass or abrasives, mining, construction, sand blasting or cutting stone. The main overlying theme for all of the occupations above is the heavy amount of dust that is created as a bi-product of whatever sort of work is getting done. So it's not necessarily the actual usage of silicon that leads to silicosis but the form that the silicon takes to make its way into your body that is truly harmful to the body. Specifically the silicate particles imbed themselves permanently into the lung tissue making it harder to breathe and essentially over time weakens the immune system and the overall condition of the body. Silicosis directly won't lead to death but indirectly can be responsible for many mining related deaths later in life. In Radersburg there is large production of rock crushing, dirt screening and transporting of dirt from various locations. Throughout an entire day's work there is constant disturbance of the dirt that is just lying around making its way into the breathable air, and that is where the potential problem of silicosis becomes a concern.

Where are Silicates?

Silicon occurs naturally and is the eighth most common element in the universe; it is rare that pure silicon will occur in a free form. The way that silicon harms humans is by the way it is distributed as different dust and particles that are able to become breathable. Since roughly over 90% of the earths crust is silicate based its easy to say that you can have an encounter almost anywhere in nature where dust is a bi-product. Silicon in its free form has a market on a global level primarily used in steel refining, and other high end chemical manufacturing. As far as goes silicates those are used in softer material, such as clays, stucco, cement and things such as that. Situationally you can be exposed with different sources of silicates but what classifies the true root of all the issues that come along with silicosis is anytime any sort of silicate dust being created as a bi-product of what ever manufacturing or mining may be taking place. It is safe to say that there is a chance that we all will cross paths with a source of silicosis through out our life. It is all a matter of what other factors come into play when speaking about the original source of a person's interaction for diagnosis. A disease as hard to diagnose as this one requires more than just a one time interaction with silicates. Silicosis generally develops over time when there is a consistent exposure of high amount of concentrations of silicates. The unfortunate part is that much of the industrial niche of our economy generates some sort of airborne bi-product that typically can have harsh health side effects.

How Do Silicates Get From Point A to Point B?

Silicates, the root of all evil for silicosis, aren't hard to find at all. In fact through a normal day each of us cross paths with silicates without even being aware of it. So really there is nothing to be concerned with for your health if the only time that you recognize silicates are in an observational state. However if at any point and time there is breathable dust that is combined with dirt and rock sediment blowing around or suspended around the air you breathe, you are in the prime situation to be exposed to the pre-cursers of silicosis. Since silicates have the most abundant content in the Earth's crust, the Earth's crust is the main "reservoir" for concentration of what causes silicosis. With that being said the main way that silicates make their way around the world is by way of how sediment is deposited and where rocks are made. This means silicates can move as floating molecules through water, they also have the capability to be able to be suspended in the air for certain periods of times, and then through their course of being aloft in either the water or air they are deposited just like any other sort of sediment and the process continues.

Bioavailability

There are two general ways to describe how silicates make their way into the food chain, and become a digestible nutrient. The first idea is focused around the development of primary producers of an aquatic setting. According to oceanographer T. James Noyes of El Camino College, the beginning stages of bioavailability in the ocean are within the variations of phytoplankton. Some phytoplankton uses silicates to create their exterior shell, and since they are the primary producers of this ecosystem, they are on the bottom of the food chain and are creating a food source for all the predators that link to silicate-based phytoplankton. Silicates in this scenario are considered an essential nutrient because if there is a lack of availability, which can limit the growth of silicate-based phytoplankton. The other way that silicates have been known to have an impact on the food chain is through our own manipulation of science. According to Life Extension Magazine, silica can have serious harmful characteristics depending on the original source of silicon. What this means is if the alteration of the silicate compound does not occur naturally in a biological system there can also be some serious toxins that come along with the supplement. Where as if the silicate compound is already present in nature it is the safest of supplements to be using. Unfortunately it is really hard to be able to fully absorb the nutritional value of silicate-based plant extracts. Due to our inability of producing soluble orthosilicic acid from a lack stomach acidity, it is hard to breakdown silicates. In Belgium two scientist tackled the idea of making it easier to digest the nutritional part of silicates and have it used to enhance peoples' health. Now on the market is an stabilized orthosilicic acid concentrate that can be used to help the beginning stages of breaking down silicon at a digestible level. Currently this method is being used to mitigate negative effects of age on our health as well as being highly recommended for those who are suffering with osteoporosis.

What Impact Does Silicosis Have on Human Health

When silicon is in the form of crystalline silica and comes in contact with human lung tissue it is completely toxic. The silicates embed themselves into the lining of the upper lobes in the lungs and create what is recognized as nodular lesions.They are 3 different levels to categorize the intensity of the growth of silicosis. The least corrosive is what is described as simple or ordinary silicosis, which means there was generally a low amount of free silica exposure for a period of around 20 years or more, which then at that point symptoms become more observable. Next is what is called accelerated silicosis, which means there was generally a higher amount of concentrated dust that was breathable, and the effects usually surface in a shorter period of time, such as 4 to 8 years. Lastly the most intense of all silicosis diagnoses is what is described as acute silicosis, which means this patient would have the highest amount of exposure. Unfortunately there is not much that can be done to reverse the negative side effects of what damage has been done, the only possibility is to lessen the effects from becoming worse.

Oddly enough there is no real test for silicosis just a three step process to drawing a conclusion of what could be silicosis. According to Rod De Llano an attorney at law the first thing the person suffering from the disease should show a history of being exposed to the silica dust in high quantities, next an x-ray should be done that would reveal damaged lung tissue, and lastly a Pulmonary Function Test could be run to show restrictiveness in the air passageway. The U.S. National Library of Medicine has stated that people who have silicosis have a higher rate of becoming diagnosed with tuberculosis, due to an unknown connection of silicosis and a weakened immune system.

How to know you're doing the best you can to prevent

The best way to prevent silicosis from being an avid concern is always follow OSHA & MSHA (Occupation Safety and Health Administration & Mining Safety and Health Administration) stipulations for working conditions as well as knowing what is useful in certain situations. OSHA has even generated a PEL restriction in work places. This means there is a Permissible Exposure Limit to how much crystalline silica exposure a worker can have during the course of an eight hour shift. Believe it or not there are several precautionary steps that are advertised on the market to help with working conditions. Primarily they are variants of different types of air purification systems. They are ranging from small personal usage to large shop size, within that spectrum there are a lot of filters on the market that provide for different types of dust and only accommodate to certain size particles, so its important to know in what situation you fall under for personal protective equipment. According to the OSHA Fact Sheet: Crystalline Silica Exposure Health Hazard Information, when a respirator is required for basic protection only a certified N95 NIOSH should be worn. If the situation calls for a higher level of protection such as when drilling into rock, or any abrasive blasting, OSHA calls for a certified CE respirator. The most important thing to keep in mind during silicosis prevention, is be aware of your surroundings, and know how to protect yourself properly against these debilitating dust particles.