There have been concerns lately about the hazards of crystalline silica in the new energy process of Fracking. Now might be a good time to highlight some of the basic issues with crystalline silica. Silica, a common mineral in the earth’s crust, is a major component of sand, rock, and mineral ores. Breathing it is a serious health concern. It can cause scar tissue to form in the lungs, reduce the lungs’ ability to extract oxygen from the air, and cause a disease known as silicosis.
There are three types of silicosis: chronic, accelerated, and acute. The most common type-chronic silicosis is a uniquely occupational disease resulting from moderate exposure to crystalline silica over a long period (10 years or more). The disease can be progressive, disabling, and can lead to death. According to the Occupational Safety and Health Administration 1,400 people died of silicosis from 1990 through 1996 (OSHA, 1972).
Exposure to crystalline silica may also increase the risk of developing tuberculosis and other nonmalignant respiratory diseases and contribute to renal and autoimmune respiratory diseases. Also, the International Agency for Research on Cancer has designated crystalline silica as a “known human carcinogen”.
In spite of the dangers, OSHA reports that more than two million workers are regularly exposed to crystalline silica dust. For example, many constructions activities-such as highway repair, masonry, and concrete work, and rock drilling-expose workers to silica. For construction workers, exposure to this hazard may occur when drilling rock, cutting concrete and other masonry products, and blasting.
Engineering controls for this hazard, such as exhaust ventilation and blasting cabinets, are very cumbersome and may not be feasible. So the next option available to supervisors is to protect workers by controlling their exposure by rotating them as much as possible. Supervisors may also consider using a respirator program, as outlined in Title 29 Code of Federal Regulation 1910.134 (29 CFR, 1998). Supervisors also should ensure that workers are informed of the following information as they relate to working with silica:
- Hazards/illnesses that may be caused by exposure
- Proper conditions/precautions for safe use or exposure
- Nature of operations that could result in exposure
- Safe work practices for its handling, use, or release
- Proper housekeeping practices
- Purpose, proper use, and limitations of respirators
- Increased risks of combining smoking and exposure
When supervisors cannot reduce exposure to silica by limiting the concentrations, they must use a program of respiratory protection to protect every worker who is exposed. This process begins with identifying workers who will need to use a respirator and getting them a physical to ensure that they can properly wear one. Workers are then fitted with an appropriate respirator and trained on its use and maintenance. A Safety, Health, and Environmental Specialist assigned to the organization can assist in these steps.
When workers have been exposed to dust that contains silica, their clothing or coveralls should be vacuumed. They should not clean their clothes by blowing or shaking them. In addition to clothing, exposed surfaces should be kept free of silica dust. If the dust on these surfaces is disturbed, it could become airborne and breathable. Dry sweeping and using compressed air for cleaning floors and other surfaces should be prohibited. When vacuuming is used, the exhaust air from the vacuum should be filtered. Gently washing the surfaces is preferred, when practical. All food, beverages, tobacco products, nonfood chewing products, and unapplied cosmetics should not be used in work areas with silica dust. Workers should also be able to wash their hands with soap and water after exposure.
– Occupational Safety and Health Administration Instruction CPL 2-2.7, October 30, 1972.
– Title 29 Code of Federal Regulation 1910, Section 134, “Respiratory Protection,” April 23, 1998.
– Occupational Safety and Health Administration Semiannual Regulatory Agenda, 68:73196-73228, Sequence Number 90 in part 11,1218-AB70-2103, “Occupational Exposure to Crystalline Silica,” December 22, 2003.