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Silicosis Update

Posted on by Jacek Mazurek, MD, MS, PhD and David Weissman, MD

 

Silicosis is a potentially fatal but preventable occupational lung disease caused by inhaling respirable particles containing crystalline silicon dioxide (silica). Quartz, a type of crystalline silica, is the second most abundant mineral in the earth’s crust and workers across a wide range of occupations and industries are exposed to silica-containing dusts. The risks, causes, and prevention of this avoidable disease have been known for decades. There is no cure for silicosis and only symptomatic treatment is available, including lung transplantation for the most severe cases.  New national data have become available since a prior report on silicosis surveillance was published earlier this year. The new data show that silicosis continues to cause or contribute to the deaths of about 100 Americans each year. There were 88, 103, and 111 such deaths in 2011, 2012, and 2013 respectively.

The most common form of silicosis, chronic silicosis, takes at least 10 years from first exposure to develop and death does not typically occur until many years after that. Onset of silicosis can be faster and the severity of disease worse in the setting of high level exposures, which can cause accelerated or acute silicosis. From  2011-2013, 12 people younger than 45 years of age had silicosis listed as causing or contributing to death.  Although we do not know the details of their cases, this is concerning because silicosis deaths in these young adults may reflect higher exposures than those causing chronic silicosis mortality in older individuals.

Examples of occupations with known high silica exposure include: mining, quarrying, sandblasting, rock drilling, road construction, pottery making, stone masonry, and tunneling operations. New settings for occupational exposure to respirable crystalline silica continue to emerge. For example, hazardous silica exposures have been newly documented in the United States during hydraulic fracturing of gas and oil wells (see related blog)  and during fabrication and installation of engineered stone countertops (see related blog).

While silicosis mortality in the U.S. has declined over time, the continuing occurrence of silicosis deaths in young adults and reports of new occupations and tasks that place workers at risk for silicosis underscore the need for strengthening efforts to limit workplace exposure to respirable crystalline silica. Effective silicosis prevention strategies for employers are available from the Occupational Safety and Health Administration (OSHA) and NIOSH.

Healthcare providers should consider reporting silicosis cases to their health departments. In 2010, silicosis was a reportable condition in 25 states (click here for more information).  State health departments can help strengthen silicosis prevention efforts by identifying silicosis cases through review of state morbidity and mortality data and investigating the circumstances surrounding silicosis cases.

 

Jacek Mazurek, MD, MS, PhD and David Weissman, MD 

Dr. Mazurek is the Lead Research Epidemiologist in the NIOSH Division of Respiratory Disease Studies.

Dr. Weissman is Director of the NIOSH Division of Respiratory Disease Studies.

Posted on by Jacek Mazurek, MD, MS, PhD and David Weissman, MD

77 comments on “Silicosis Update”

Comments listed below are posted by individuals not associated with CDC, unless otherwise stated. These comments do not represent the official views of CDC, and CDC does not guarantee that any information posted by individuals on this site is correct, and disclaims any liability for any loss or damage resulting from reliance on any such information. Read more about our comment policy ».

    The reported deaths are tragic and clearly the result of overexposures on the job. As noted in the article, these deaths are completely preventable. What are needed to prevent such outcomes are dust control, dust monitoring, medical surveillance, and strict compliance with the current PEL. An occupational health program that incorporates these elements was developed by the National Industrial Sand Association (NISA) and I recommend it for your consideration. It can be accessed at [http://www.sand.org/Silica-Occupational-Health-Program]. You also should be aware of a recent NIOSH publication, Dust Control Handbook for Industrial Minerals Mining and Processing, Report of Investigations 9689/2012, NIOSH Pub. No.2012-112. It can be accessed through the following hyperlink: http://www.cdc.gov/niosh/mining/pubs/pubreference/outputid3675.htm. Many of the dust controls identified for the industrial minerals industry potentially could be applied to other industrial sectors . . . perhaps with some modification.

    Thank you for your comment. We also encourage those interested in silicosis prevention to review the materials found at the web links you have provided and also materials accessible from the NIOSH web page on silica. Careful attention to known, effective interventions can prevent silicosis.

    Thanks for the article. I read once about a clothes cleaning process wich can remove the dust the remains in the uniforms. Do you have more recent information of this sytem?

    In 2004, NIOSH published research conducted in partnership with Unimin Corporation to design a clothes cleaning system to prevent fugitive emissions of silica dust from workers contaminated clothing. NIOSH published a report on the Internet including the design specifications so one could construct a clothes cleaning booth. This design used high pressure air, an approach that is not approved by current Mine Safety and Health Administration (MSHA) regulations. To use this design at a mine, a waiver must be obtained from MSHA. The link to the report which is available as a pdf file can be found at: http://www.cdc.gov/niosh/mining/works/coversheet1300.html. At present, commercially manufactured units can be found on the Internet using your favorite search engine and the keywords, “clothes cleaning booths.”

    What about the metal working industries?

    Airborne Aluminum Silica particulate in the mist?
    Airborne Titanium Silica particulate in the mist?

    Because most tend to use emulsion based cooling fluids; the higher speeds and feeds, High pressure and Coolant through Spindle applications all add to the creation of more thoracic or breathable content when researching the average particle sizes created.

    Thank you for your comment. There are many silicate materials partly composed of the element silicon. Silicosis is caused by respirable crystalline particles of the compound silicon dioxide, not by other silicate materials. That said, occupational exposure to metalworking fluids can potentially case a variety of health effects. Some of the prominent ones include hypersensitivity pneumonitis, chronic bronchitis, impaired lung function, asthma, and irritant dermatitis. NIOSH has posted more detailed information on its website. Also, OSHA has posted a safety and health best practices manual for metalworking fluids:https://www.osha.gov/SLTC/metalworkingfluids/metalworkingfluids_manual.html.

    I have not seen any studies or OSHA violations concerning concrete and concrete products in Big Box stores. Since I work in a “big box”, every day I see broken bags and workers sweeping it up (putting the dust into the air). Sometimes the haze is so thick we open the overhead door to allow for ventilation. The dust settles onto the products consumers buy. When disposed of these bags are thrown into the compactor while usually has a positive airflow blowing more of the dust out into the area and the store meanwhile the workers throwing it into the compactor are spitting out the grit they just inhaled. It seems management (or the health and safety people) is not concerned for the well being of the workers exposed to this on a daily basis.

    Thank you for your comment. The risk for silica-induced lung disease is related to inhaling sufficient amounts of respirable crystalline silica. These are particles that are small enough to enter the lungs. The greatest concerns for silica exposure from concrete is related to cutting, grinding, and demolition of concrete structures. This can generate large amounts of airborne small particles that include silica from the stone aggregates that were added to the cement when the concrete was made. Cement itself does not contain much crystalline silica. Nevertheless, concrete mixing is associated with some crystalline silica exposure (Flanagan et al 2003).

    Even if the clouds of dust that you describe in your workplace aren’t made up of fine particles that contain much crystalline silica, they can still have other health effects. For example, alkaline compounds like lime can be quite irritating. Hexavalent chromium in cement can cause allergies. You may find this web page to be of interest: http://www.elcosh.org/document/1563/d000513/Cement%2BHazards%2Band%2BControls%2BHealth%2BRisks%2Band%2BPrecautions%2Bin%2BUsing%2BPortland%2BCement.html?show_text=1.

    There are steps that if taken could reduce dust exposures in your workplace. For example, cleaning up spills and settled dust with HEPA vacuuming generates much less airborne dust than dry sweeping or cleaning with compressed air. Sufficient amounts of room ventilation moving away from workers might also be helpful. Local exhaust ventilation that captures dust directly from the compactor would also be a good engineering control to consider. If appropriate to your situation, you might want request a NIOSH Health Hazard Evaluation of your workplace. Information on how to do this is available at this web link: http://www.cdc.gov/niosh/hhe/

    In this context it could be of interest reading the Hazard Alert from the OSHA-NIOSH “Worker Exposure to Silica during
    Countertop Manufacturing, Finishing and Installation”

    Thank you for your question. The blog provides a link to this report, which contains a table showing data from 1999 to 2013: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6423a7.htm?s_cid=mm6423a7_w. You may also be interested in this chart, which shows data over a much longer period from 1968 to 2010. http://wwwn.cdc.gov/eworld/Data/Silicosis_Number_of_deaths_crude_and_age-adjusted_death_rates_US_residents_age_15_and_over_19682010/768 Note that the methodology of data collection was different in the chart than for the table (using of “entity axis” instead of “record axis” http://webappa.cdc.gov/ords/norms-glossary.html), which is why the numbers are slightly different. Although silicosis mortality in the U.S. has declined over time, silicosis deaths continue to occur, including in young adults. Also, new occupations and tasks that place workers at risk for silicosis continue to be reported. So silica exposure and silicosis continue to be relevant concerns.

    The prognosis of silicosis depends upon the chronicity and severity of lung damage caused by this condition. Prevention is a very important aspect of the management of this condition. Occupational safety standards need to be implemented rigorously in order to prevent this condition and reduce morbidity and mortality.

    What about the metal working industries?

    Airborne Aluminum Silica particulate in the mist?

    Can you expand the answer please?

    We were unable to identify peer-reviewed scientific literature focusing specifically on health effects of aluminum silicates in metalworking fluid mists. If readers of the blog have additional information to provide, please post your thoughts!

    Yo hace 30 años que aprendía el oficio de fontanero. He soldado mucho plomo y siempre he notado ese humo toxico. Mi pregunta es si corro algún riesgo de contraer silicosis. Es algo que siempre me ha preocupado. Tengho esa duda sobre el plomo.

    Muchas gracias por el artículo.

    English Translation from NIOSH

    I learned to be a plumber 30 years ago. I’ve experienced a lot of lead and have always noticed the toxic smoke. My question is, do I run a risk of silicosis? This is something that has always bothered me. I have this doubt about lead. Thank you very much for this article.

    Thank you for your comment. No, you cannot get silicosis from soldering pipe with lead-based solder. Silicosis is caused by inhaling dust that contains respirable crystalline silica. The task of soldering pipe connections should not in itself cause silica exposures.

    However, soldering with lead-based solder is associated with other serious hazards, including exposure to lead. You need to be aware and reduce exposure to the lead-containing fumes and smoke that you described because lead can have serious health effects.

    Hazards associated with soldering are described in a document from the Lawrence Berkeley National Laboratory: http://www2.lbl.gov/ehs/ih/pdf/safeSolderingFinal.pdf. OSHA has posted a document describing ways to control lead exposures in the construction industry: https://www.osha.gov/dts/osta/otm/otm_v/otm_v_3.html.

    Thanks for this very informative post on your website. and we hope you will keep it up. we are also organising a program for public awareness in my village.. So this information is very helpful for me. Thanks again..

    am your typical homeowner. I just had a handy man help cut my existing limestone (maybe they were granite) sink countertops. He tented the bathroom and had me hold a shop vac to collect the dust. I wore a MSA half mask (P100) respirator but I have a beard so its hard to get a perfect seal and afraid i was breathing some of the dust. Should I be worried about a 2 day exposure of of the dust? Im kind of a hypochondriac. Im assuming these precautions are for sustained exposure if this was your career?

    Kind of like cigs will give you cancer but if you tried a pack or two you will be find in the long run.

    Thank you for your comment. Please note that we can’t provide individual medical advice. However, I congratulate you on thinking about the hazard of dust exposure and taking steps to prevent it! As you say, there is a relationship between level of exposure and risk of disease. It does not sound like you had an extremely massive exposure to dense clouds of respirable silica, which would be the level of exposure needed to have a chance to cause problems after such a short duration of exposure. Still, your note raises some interesting issues. Using a Shop Vac as you described to collect dust may have helped. This publication describes using a Shop Vac that is integrated into the power tool as a way to control exposures: http://www.cdc.gov/niosh/docs/wp-solutions/2015-185/pdfs/2015-185.pdf. Studies used a regular shop vacuum which had a high efficiency disposable filter bag as a pre-filter and a cartridge filter. Wet cutting methods are also a well-established way to prevent dusts from getting into the air in the first place and might have been applicable to your situation. As you indicate, a negative-pressure respirator does not provide optimal protection without a good facial seal. Without such a seal, the wearer breathes in unfiltered air from around the respirator. That is why people using negative pressure respirators should not have facial hair (moustache, beard) that interferes with the facial seal and in part why NIOSH recommends that respiratory protection (respirators) be used in the context of a comprehensive respiratory protection program that provides users with annual respirator fit testing.

    I like this blog, I’m looking for information about lung disease and all of them in this blog. may I ask, what is called a particle containing crystalline silicon dioxide (silica)?
    thanks for the post,

    Thank you for your comment. Silicosis is caused by breathing in airborne particles that contain crystalline silica and small enough to reach deep into the lung. This is what we mean by the term “respirable crystalline silica.”

    Silicosis affects the lungs by damaging the lining of the lung air sacs. Once this begins, it leads to scarring and, in some situations, to a condition called progressive massive fibrosis. This condition happens when there is severe scarring and stiffening of the lung, which makes it difficult to breathe.

    People with acute silicosis experience cough, weight loss, tiredness, and may have fever or a sharp chest pain. You may also have shortness of breath over time, especially with chronic silicosis. Your healthcare provider might hear crackles or wheezing when they listen to your lungs. Having silicosis increases the risk of other problems, such as tuberculosis, lung cancer, and chronic bronchitis.

    Each type of silicosis affects the body somewhat differently:

    In acute silicosis, the lungs become very inflamed and can fill with fluid, which causes severe shortness of breath and low blood oxygen levels.
    In chronic silicosis, the silica dust causes areas of swelling in the lungs and chest lymph nodes, which makes breathing more difficult.
    In accelerated silicosis, swelling in the lungs and symptoms occur faster than in chronic silicosis.
    Over time, lung capacity decreases, and people with silicosis may need support with oxygen and other devices to help them breathe.

    I have been involved in the industrial ceramic pottery and clay manufacturing business for 40 years. I do not know of one individual who has gotten silicosis. The TWA of PELs are way above what any individual would inhale. I spoke with a friend from a major feldspar supplier and asked him if he had ever heard of anyone in the ceramic industry over the last 40 years getting silicosis. I was surprised to hear that there had been 2 individuals. As it turned out, these were workers who used skip loaders to empty rail cars full of kaolin and ball clays many years ago before much attention was spent on silicosis. This exposure occurred over many years. They would come into the office after a day of work covered in clay dust and never wore a face mask. But he said the critical co-factor was smoking. If they had not smoked, it was unlikely they ever would have gotten silicosis. The tar from smoking clings to the fine particles and increases greatly the potential for silicosis. If you have good fresh air circulation and avoid generation of dust, you are going to be fine.

    Thank you for your comment. We are sorry to hear about workers who developed silicosis. We would caution against blaming their silicosis on smoking. By far, the most important factor in getting silicosis is breathing in respirable crystalline silica particles. Although some have suggested that smoking may increase risk, we are not aware of research showing that “The tar from smoking clings to the fine particles and increases greatly the potential for silicosis.” Still, no one should smoke because it increases risk for many diseases, including lung cancer, chronic obstructive pulmonary disease, cardiovascular disease, and others. OSHA has estimated in its recent notice of proposed rulemaking on occupational exposure to respirable crystalline silica that there would be 11 excess deaths from silicosis per 1,000 workers exposed to respirable crystalline silica at the current permissible exposure limit (PEL) for general industry of 0.1 mg/m3 over a 45-year working lifetime. So, if exposures in your own workplace have been at or below the current PEL, it is not surprising that you don’t personally know people with the disease. It is important to note that silica exposure isn’t just associated with silicosis. OSHA also estimated 22-29 excess deaths from lung cancer, 83 excess deaths from non-malignant respiratory disease (including silicosis and chronic obstructive pulmonary disease), and 39 excess deaths from renal (kidney) disease per 1,000 workers after 45 years of regular exposure to respirable crystalline silica at the current PEL.

    Thank you for your comment. The most important way to escape from getting COPD is to avoid inhalation exposures that cause the disease. It is important to not smoke, since smoking is the most common cause of COPD. It is also important to avoid hazardous occupational exposures that can cause COPD. An authoritative statement from the American Thoracic Society found that about 15% of COPD was attributable to occupational exposures, including respirable crystalline silica. Even people who have COPD can take action to reduce its effects. According to the National Heart, Lung, and Blood Institute, “COPD has no cure yet.. However, lifestyle changes and treatments can help you feel better, stay more active, and slow the progress of the disease.” See http://www.nhlbi.nih.gov/health/health-topics/topics/copd/treatment. Finally, people who have chronic respiratory symptoms like cough, production of phlegm, and shortness of breath should seek medical attention for appropriate evaluation and treatment.

    I come from Indonesia, it’s nice share and i want to ask about this post, According to you how do we know there crystalline silicon dioxide in the air? and how do we prevent crystalline silicon dioxide in the air? Thanks before,

    Thank you for your question. The only way to know for sure if crystalline silicon dioxide (silica) is in the air is to collect a sample and have it analyzed in a laboratory. However that is not always possible to do. Because silicon dioxide is one of the most common minerals on earth, it is often found in occupational settings where dust is being created from abrasive blasting, sanding, grinding, drilling, cutting, crushing, mining or working with sand, stone, rock, concrete, brick, block, and mortar. Unless you can sample and analyze the air, you should assume that respirable crystalline silica is present and control the dust being created as best as you can. Because there are many different types of work processes potentially associated with silica exposure, there are also many types of exposure controls. Depending on the setting, these might include measures like substitution of less hazardous materials, use of processes like wet cutting, and use of ventilation controls. For more information, you may find the NIOSH and OSHA web sites to be helpful. http://www.cdc.gov/niosh/topics/silica/default.html and https://www.osha.gov/dsg/topics/silicacrystalline/

    I did not know that this disease exists. In Brazil, for example, we have many people who work in places that offer this kind of health risk. And, unfortunately, nothing is said about this disease. I am grateful for this enlightening article and I cheer for the Brazilian authorities to do something to help people in this situation.

    Hello,

    Very nice post and very informative for us. Post reading this able to know about disease about described. Thanks to share it with us.

    your article is very useful once and beforehand I would like to ask permission from you, to implement it as a material for doing the coursework, which is about the lung disease silicosis kind, thank you

    you should assume that respirable crystalline silica is present and control the dust being created as best as you can,Very informative site and also thanks for the Silicosis Update

    I am an RN/Advocate who assists former nuclear workers with getting qualified for Dept of Energy benefits. I have many Nevada Test Site workers who were admittedly exposed to large amounts of silica, who have symptoms of shortness of breath, cough etc. who are not being diagnosed due to the test results that are expected. These guys are being monitored every 3 years with a b-read and PFT’s but rarely does the b-read show even a 0/1 profusion. They all have multiple lung nodules. I’ve been able to get a couple of them diagnosed but by the time they are they are so debilitated. We all know it takes, 20,30 even 40 years to show up on a chest x-ray. This is very unfair to these people. I’m asking: Do you know of any medical professional contacts that may have a method of testing that will show the early development of silicosis? Thank you

    Thank you for your question and for your efforts to help these workers. People with chronic respiratory symptoms like shortness of breath, cough, and exercise limitation due to breathlessness should have careful medical evaluations to determine causes and best approaches to treatment. In general, the most knowledgeable physicians to carry out this type of evaluation are pulmonary disease specialists. A comprehensive evaluation would include medical history (including exposure history), physical examination, and appropriate laboratory studies. Such laboratory studies might include pulmonary function studies to evaluate for airflow limitation and abnormalities in gas exchange; chest imaging studies; and other studies as appropriate. In terms of chest imaging studies, high-resolution computed tomography of the chest is more sensitive in detecting changes of silicosis than plain chest radiography. Also with regard to chest imaging, your report of multiple lung nodules in all the workers is concerning. Hopefully, careful clinical evaluations will document why they are present.

    Thank you Jacek Mazurek, MD, MS, PhD and David Weissman, MD. This information about silicosis is very good.. Now I know about that.

    come from Indonesia, it’s nice share and i want to ask about this post, According to you how do we know there crystalline silicon dioxide in the air? and how do we prevent crystalline silicon dioxide in the air? Thanks before,

    If you are using sand for abrasive blasting, or if you are drilling, crushing, or smoothing or polishing stone or concrete, you are most probably creating a dust that contains silica. To be sure requires air sampling and chemical analysis. However you wait to confirm that the dust contains silica you may already be exposed. Whenever you are cutting, drilling or abrading rock, stone, or sand you should assume that silica dust is there and take steps to reduce your exposure, unless you first confirm by sampling that it is not there.

    There is a short simple document that may be of use to you. It is called: A Guide to Working Safely with Silica. If it’s Silica, it’s Not Just Dust. It can be downloaded at this web link: http://www.cdc.gov/niosh/pdfs/silicax.pdf. Also, NIOSH maintains a web page with many resources related to silica and silicosis. It is found here: http://www.cdc.gov/niosh/topics/silica/.

    information which is nice , sometimes we do not care about our health , thanks for the info is very nice article

    Silicosis is very dangerous lung disease and according to my information i think this is caused by crystalline silica dust, and is marked by inflammation and scarring in the form of nodular lesions in the upper lobes of the lungs, People affected by this has short life form but even leading big industries and miners not even care about workers by not providing them security masks and other extra safety equipments and suits. Its time for taking actions against these type of Industries by Government.

    I really liked your site, in my opinion is the best I’ve found .
    I’m from Argentina , and do not speak English very well , but recommend your blog on my pages .
    Thank you
    HossanaNet

    Frank Konarski Rios:

    This is a great, informative and thought-provoking article by Dr. Mazurek and Dr. Weissman. As a housing developer, I very much care about my contractors and the work they do, and this will lead me to cause my partners and staff to be extra vigilant in developments that encompass the installation of stone and masonry products, and hopefully other developers will also come to also pay closer to OSHA prevention strategies.

    Frank Konarski Rios, Housing Developer & Landlord
    Tucson, AZ & Nogales, AZ

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