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Silica Hazards from Engineered Stone Countertops

Categories: Construction, Manufacturing, Personal Protective Equipment, Respiratory Health

A new engineered stone countertop product known as “quartz surfacing,” was created in the late 1980s by combining quartz aggregate with resins to create a product for use in home building and home improvement.  Manufacturing of this material, including products such as CaesarStone™, Silestone™, Zodiaq™, or Cambria™ is a fast growing industry.  First made in Israel and Spain, production of these materials has grown world-wide, driving quartz slab imports to the U.S. up 63% between 2011 and 2012 and 48% between April 2012 and April 2013 (Schwartzkopf 2013, StatWatch 2013).  Quartz surfacing materials may contain up to 93% crystalline silica (Dupont 2010).  In contrast, the percent of crystalline silica in a slab of granite is less than 45%, darker color granite has a lower percentage (Simcox et al. 1999).  Workers who fabricate and install quartz surfacing are at risk for overexposure to silica released during sizing, cutting, grinding and polishing.  Prolonged inhalation of dust from silica-containing materials can lead to silicosis (scarring of the lungs).  In addition to silicosis, scientific evidence indicates that occupational exposure to crystalline silica puts workers at increased risk for  other serious health conditions: chronic obstructive lung disease, lung cancer, kidney and connective tissue disease, and tuberculosis.  The focus of this blog is on silicosis, which has occurred in multiple workers in this industry.

Silicosis

Silicosis is caused by breathing in very fine (“respirable”) dust containing crystalline silica. Initially, individuals may be developing disease even without respiratory symptoms. Chronic silicosis typically develops over 10 or more years of exposure to low levels of respirable crystalline silica. However, high levels of exposure can cause faster development of the disease. The diagnosis is usually made through a chest radiograph, which should be classified by a NIOSH-certified Reader

Cases of silicosis have been reported among engineered stone countertop workers in other countries.  In a study published in 2012, researchers in Israel found 25 patients referred to their National Lung Transplantation Program with silicosis who shared a common exposure history. All had worked with the same commercial brand of decorative quartz surfacing material for 10–14 years and performed similar dry-cutting of the material for kitchens and other countertop applications (Kramer et al. 2012).  Most recently, 46 cases of silicosis were reported in Spain in workers cutting and installing engineered stone countertops with silica content of 70-90% (Pérez-Alonso et al. 2014).  These individuals were young (ages 29–37 years) and worked in the industry for 9–17 years.

While no reported cases of silicosis  in the U.S. have been linked to quartz surfacing materials, recent research indicates that exposures to silica-containing dust while working with these materials may approach or exceed the Occupational Safety and Health Administration (OSHA) current Permissible Exposure Limit (PEL) (Phillips et al. 2013).  Multiple inspections by OSHA (U.S. Department of Labor) have documented overexposures to silica at stone fabrication shops working with a combination of natural stone and quartz surfacing materials (OSHA 2011).  These overexposures would indicate U.S. workers in this industry are at risk of developing silicosis as well as the other multiple health conditions associated with silica exposure.

Protecting Workers

We can apply what we know about reducing exposure to dusts from natural stone products to quartz surfacing materials.  The key to prevention is keeping dust out of the air.  Hazard alerts published in California and Washington State described exposure to silica dust and other hazards related to fabrication of granite and natural stone products and provided dust control recommendations.  Whenever possible, cutting, grinding and shaping should be done wet.  Ventilation and filtration systems should be used to collect silica-containing dust at its source.  If these engineering controls fail to eliminate the risk, then use of at least a NIOSH-approved N95 respirator is recommended.   

In addition to information and resources on silica and silicosis for employers and employees provided by NIOSH and OSHA, the Center for Construction Research and Training’s website “Work Safely with Silica” is searchable by work task, material and tool.

Help Wanted

There is relatively little sampling data available on quartz surfacing materials. NIOSH encourages fabricators to submit a request for a Health Hazard Evaluation (HHE).  More information can be found on the HHE Topic Page.  Researchers at NIOSH are especially interested in seeing  a state-of-the-art engineered stone countertop manufacturing facility to help us understand how to best control exposures to quartz surfacing material.  If you are interested in working with NIOSH, you can contact us using the comment section below, e-mail us at nioshblog@cdc.gov, or submit an HHE at the link provided above. 

Finally, if individuals working with countertops have health problems or are concerned about past exposures, they should see a healthcare provider and inform them about their concerns. Healthcare providers who suspect that their patients’ health problems may be caused by working with quartz-containing materials are encouraged to report their concern to their state health department.

Web Pages of Interest

References

Click here for the references used in this blog entry.

Karen Worthington, MS, RN, COHN-S; Margaret Filios, SM, RN; Mary Jo Reilly, MS; Robert Harrison, MD, MPH; and Kenneth D. Rosenman, MD.

Karen Worthington is a Research Scientist in the New Jersey Department of Health and Senior Services.

Capt. Filios is a Senior Scientist in the NIOSH Division of Respiratory Disease Studies.

Mary Jo Reilly is an Epidemiologist in the Division of Occupational & Environmental Medicine at Michigan State University.

Dr. Harrison is a Professor of Medicine at UC San Francisco and Chief of the Occupational Health Surveillance and Evaluation Program at the California Department of Public Health.

Dr. Rosenman is a Professor of Medicine and Chief of the Division of Occupational and Environmental Medicine at Michigan State University.

Public Comments

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 ».

  1. March 12, 2014 at 7:09 am ET  -   constructeur de maison 77

    I am an architect and I am always eager to see the creativity of others, relevant article.

    Link to this comment

  2. March 13, 2014 at 1:42 pm ET  -   Clayton Doak

    This is important information since it draws attention to a silica exposure hazard. I am concerned that the term “engineered stone” does not warn workers about the potential silica exposure. Maybe “engineered silica stone” or “engineered quartz counter top” would be better…. Descriptive terminology in this case appears to be critical.

    Link to this comment

    • AUTHOR COMMENT March 14, 2014 at 3:05 pm ET  -   Karen Worthington, Margaret Filios, Mary Jo Reilly, Robert Harrison and Kenneth D. Rosenman

      Thank you for your comment. As this is a relatively new product, the terminology is still evolving. At present, “quartz surfacing materials” appears to be the term preferred within the industry. As we continue to work in this area we can help refine the terminology used by safety and health professionals.

      Link to this comment

  3. March 17, 2014 at 10:49 am ET  -   George Kilens, CIH

    Great article! We (OSHA) actually found worker silica exposures (via personal sampling) to be 50% of the OSHA PEL during stone cutting and polishing work under very wet operating conditions (no local exhaust used). The product was either Silestone™ or Zodiaq.

    Link to this comment

  4. March 18, 2014 at 4:52 am ET  -   Dr. Dinesh Sharma

    Really helpful and informative piece! Impressed a lot and i’m really willing to read something more from your side. Keep posting!

    Link to this comment

  5. March 20, 2014 at 11:10 pm ET  -   Batu Giok

    wow amazing..
    thanks

    Link to this comment

  6. March 25, 2014 at 6:07 pm ET  -   Stu Bailey

    I am very interested in this topic in this industry. I have created a device that reduces exposures to silica in these shops. For my final report for my master’s degree I explained ways to reduce silica exposures in marble and granite shops. I tested it in four shops and reduced exposures in all the shops below the OSHA-PEl. When used correctly with fans strategically placed it works even better. With or without my screen I am very interested in working on this. I have a lot of experience with M & G shops and would like to share my thoughts and data.

    Link to this comment

    • AUTHOR COMMENT March 27, 2014 at 2:40 pm ET  -   Karen Worthington

      Thank you for your comment. We will contact you to discuss further.

      Link to this comment

  7. March 30, 2014 at 1:49 am ET  -   Sam Walker

    The workers should be aware of these hazards they expose themselves to. It will also help if the workers would get an early retirement package so they can healthily enjoy their golden years. There is a limit for our body’s tolerance to such work especially when we reach the age 55. Having that kind of nature for a job does something to your body over a period of time. Well, I guess it also depends on the healthcare you get.

    Link to this comment

  8. March 31, 2014 at 3:14 am ET  -   Emilio Castejón

    Many cases of silicosis were detected in Spain, where Silestone is produced. See for example
    http://www.maneyonline.com/doi/abs/10.1179/2049396713Y.0000000049?ai=15tui&

    Link to this comment

  9. April 9, 2014 at 1:30 pm ET  -   Anshul Mishra

    Myself Anshul Mishra, I want to add one important thing here that in production process we use resin and chemicals for thermo-chemical reaction of resin with quartz material. So styrin gas evaporate, this gas affect our central nervous system. It is quit harmful.

    Link to this comment

    • AUTHOR COMMENT April 22, 2014 at 7:26 am ET  -   Karen Worthington, Margaret Filios, Mary Jo Reilly, Robert Harrison and Kenneth D. Rosenman

      Thank you for your important comment. Although this blog article addressed fabrication shops as the work setting of concern, you raise a very important issue regarding potential airborne chemical hazards, including styrene, which may be present during the manufacturing process. Both the U.S. occupational health and safety research agency (NIOSH) and enforcement agency (OSHA) are further investigating the hazards associated with these engineered stone products.

      NIOSH welcomes Health Hazard Evaluation requests from U.S. employers or employees involved in manufacturing engineered stone countertops (see link on blog site). NIOSH health and safety experts would view work processes and practices, assess exposures and health, and recommend ways to reduce all occupational hazards.

      Link to this comment

  10. May 21, 2014 at 9:00 am ET  -   toto permadi

    healthy worker is very important, safety first must be.
    This is my first visit to your blog, I get a lot of useful information here. Thank You

    best regard

    Link to this comment

  11. June 27, 2014 at 6:16 am ET  -   Cassidy Bros Ireland

    Interesting article on the link between building stone and silicosis. Quartz is a very type of popular stone for residential customers. Combing quartz aggregate into an attractive mixed coloured aggregate and then the cutting of the stone does produce an enormous amount of dust. But causing silicosis, provides installers with the need to take precautions for it’s installation.

    Link to this comment

  12. July 22, 2014 at 10:23 pm ET  -   Progressive Builders

    For an architect the blog is really helpful. Impressed a lot and I’m really willing to read something more from your side. Carry on your discussion. Keep posting!

    Link to this comment

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