Unit V Literature Review
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unit_v_literature_review2.pdf
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References Roughton, J. E., & Pierdomenico, J. C. (1998). Crystalline silica: The new asbestos do we need a performance
based standard?. Professional Safety, 43(5), 12. <!Additional Information: Persistent link to this record (Permalink): https://libraryresources.columbiasouthern.edu/login? url=http://search.ebscohost.com/login.aspx?direct=true&db=bth&AN=630218&site=ehostlive&scope=site End of citation>
Section: REGULATORY NEWS
CRYSTALLINE SILICA: THE NEW ASBESTOS DO WE NEED A PERFORMANCEBASED STANDARD? Silica exposure is an ancient hazard that remains a serious threat to many U.S. workers. Those affected the most can be grouped in job classifications such as those employed as sandblasters, foundry workers and stone cutters, as well as those involved in drilling, quarrying and tunneling. Diseases associated with inhalation of silicacontaining dusts include silicosis, chronic airway obstruction, bronchitis, tuberculosis and lung cancer.
OSHA currently has a permissible exposure limit (PEL) for silica. However, increasing evidence suggests that the PEL may be too high. The lack of a standard to outline provisions for product substitution, engineering controls, respiratory protection and medical screening/surveillance has contributed to inadequate worker protection. In OSHA's attempt to improve worker protection, the agency has placed silica on its priority list.
RECENT DEVELOPMENTS On May 2, 1996, OSHA issued a compliance memorandum that provided specific guidance for implementing a Special Emphasis Program (SEP) to control silicosis. The intent is to provide inspection guidance, and thus reduce and/or eliminate the incidences of silicosis. This action means targeting all facilities or activities where a "reasonable chance of exposure above the PEL exists."
In addition, the memorandum identifies resources to help area and regional offices target inspections at particular establishments or standard industrial codes (SIC). These sources may include workers' compensation data, visual observations, chemical inventories, injury and illness recordkeeping data, and SENSOR (Sentinel Event Notification Systems for Occupational Risks) data from a (NIOSH) program of cooperative agreements with state health departments.
The memorandum addresses the steps a compliance officer can take when inspecting sites for potential crystalline silica dustrelated overexposure. Compliance officers conducting an inspection under the SEP
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could include review of OSHA regulations and other related information (e.g., recordkeeping, air monitoring, medical surveillance, respiratory protection, engineering and/or work practice controls, HazCom training, specific material safety data sheets and training).
As with focused inspections in construction, sites (targeted for inspection) that have implemented an effective, ongoing silicosis prevention program can be exempted, provided the compliance officer has determined that all existing program elements are appropriate. SEP specifies that the compliance officer can expand the inspection scope beyond crystalline silica if hazards or violations are observed.
CRYSTALLINE SILICA DEFINED Crystalline silica (SiO2) is the basic component of sand, quartz and granite rock. Crystalline refers to the orientation of the SiO2 molecules in a fixed pattern. Exposure to SiO2 is not new to industryit can be traced throughout history.
Little was achieved in the field of industrial hygiene until 1473, when Ulrich Ellenbog, a German scholar, published a pamphlet on occupational diseases. In 1556, Georgius Agricola described hazards associated with the mining industry. His De Re Metallica was translated into English in 1912: by Herbert and Lou Henry Hoover. Agricola's 12section treatment included suggestions for mine ventilation and protective masks for miners, and a discussion of mining accidents caused by lengthy exposure to silicosis.
The first comprehensive documentation on occupational disease, De Morbis Artificum Diatriba by Bernardo Ramazzini, an Italian physician, was published in 1700. The book described silicosis in pathological terms, as observed by autopsies on miner's bodies. He presented cautions he felt would alleviate industrial hazards. Unfortunately, his warnings were ignored.
The worst exposure in the U.S. occurred in 1930, at the tunnel of Gauley Bridge in West Virginia. Many workers contracted silicosis. The incident resulted in the initiation of dust suppression, respiratory protection methods and improved industrial hygiene, and the introduction of laws for compensation of silicosis victims.
Exposure to crystalline silica can occur in many types of manufacturing industries: glass and pottery; abrasives; Portland cement; maritime operations; mining; and construction. The most common exposure in construction may occur during abrasive blasting. The risk of silicosis is higher among workers exposed to abrasive blasting with silicacontaining media.
In 1974, NIOSH recommended that silica sand (or other substances containing more than onepercent crystalline silica) be prohibited as abrasive blasting material. In 1992, NIOSH published "Preventing Silicosis and Deaths from Sandblasting." In this publication, the agency specified recommendations to reduce crystalline silica exposures in the workplace and requested additional input.
HEALTH HAZARD DEFINED NIOSH estimates that one million U.S. workers risk developing silicosis. This includes 100,000 in highrisk occupations such as sandblasting, painters who perform sandblasting, rock drillers, roof bolters and foundry workers. The agency estimates that 59,000 of these workers will develop adverse health effects from crystalline exposure.
Silicosis is a fibrotic lung disease characterized by the formation of small nodules on the lungs. Symptoms may include shortness of breath, fever and cyanosis (bluish skin). In advanced cases, respiratory impairment may develop. Those exposed may develop silicosis, bronchitis, fibrosis, granulomatosis
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infections (e.g., tuberculosis) and lung cancer. Silicosis is a disabling, progressive and sometimes fatal disease that scars the lungs.
NIOSH classifies three types of silicosis:
Acute. An acute response can occur when exposure concentrations are at the highest. This can cause symptoms to develop from within a few weeks to five years after the initial exposure. Accelerated. An occurance where the result of high exposures to crystalline silica may develop five to 10 years after the initial exposure. Chronic. This longterm effect can result from prolonged exposures to low concentrations of crystalline silica. Symptoms may not develop until 10 years after initial exposure. CURRENT STATUS OSHA currently has a PEL governing respirable crystalline silica for the construction industry. The PEL is measured by millions of particles per cubic foot (mppcf), based on the percent quartz (SiO[2]) using the formula provided in the standard (29 CFR 1926.55). NIOSH sets a recommended exposure limit (REL) of 0.05 mg/m[3] for respirable quartz, as does the American Conference of Governmental Industrial Hygienists (ACGIH), with an established threshold limit value (TLV) of 0.1 mg/m[3].
OSHA's industry standard (29 CFR 1910.1000) is the same as the agency's construction standard, but provides formulas for measuring PEL in mppcf and mg/m[3]. When using the mg/m[3] formula (10 mg/m[3]/%SiO[2] + 2), and using 100 percent SiO[2], the resulting value is close to the ACGIH TLV of 0.1 mg/m[3]. The NIOSH REL is about half the TLV (0.05 mg/m[3]). Therefore, the NIOSH and ACGIH exposure limits are more conservative than OSHA's.
CASE HISTORIES The following case histories are summarized in the Centers for Disease Control and Prevention (CDC) alert, "Preventing Silicosis and Death in Construction Workers." The cases describe construction workers who died of exposure to silica or are suffering from silicosis.
Case 1. A 39yearold sandblaster was diagnosed with silicosis (progressive massive fibrosis) and tuberculosis in April 1993 after working 22 years as a sandblaster. He had noticed a gradual increase in shortness of breath, wheezing and discomfort from minimal exertion. Tissue taken from his lungs showed extensive fibrosis.
The sandblaster was first diagnosed with silicosis in 1991, after a coworker developed tuberculosis and the state health department administered chest xrays and skin testing to the entire crew. He was one of 20 workers who sandblasted welds during water tank construction. While sandblasting, this worker wore a charcoal filter respirator. During a 10 to 11hour day, he typically spent six hours sandblasting.
Case 2. A male nonsmoker was diagnosed' with advanced silicosis, emphysema and asthma at age 49 after working 23 years as a tile installer. His work included polishing and drilling tile, and he was exposed to grout dust and sandblasting. He did not use a respirator. Information about dust control reportedly was not made available to workers.
Case 3. A male nonsmoker was diagnosed with silicosis, emphysema and lung cancer at age 70 after working. 41 years as a brick mason. The diagnosis was made after an openlung biopsy (a chest xray had shown no evidence of silicosis). This worker spent time around coke ovens doing fire brick work. He wore a respirator while working in dusty conditions. Information about dust controi was not available.
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Case 4. A 47yearold male was diagnosed with severe silicosis after working 22 years as a rock driller. He was diagnosed in 1992 after suffering respiratory and heart failure. In spring 1994, while on a ventilator, the man died of respiratory failure. His autopsy confirmed advanced silicosis. Before his diagnosis, this worker had never had a chest xray. Drills he used were equipped with dust controls, which were usually inoperable.
Case 5. A male died of silicosis at age 69 after working two years as a tunnel construction worker and 40 years as a nurse. He had been exposed to silica during his two years in tunnel construction. Information about respirator use and dust control was not made available.
OSHA STANDARDS OSHA has not issued a specific performancebased standard for crystalline silica. However, crystalline silica is regulated under several other OSHA standards (Table 1).
EMPLOYEE PROTECTION PROGRAM OSHA 29 CFR 1926.55 states, "... to achieve compliance with the established PEL, the employer must first implement engineering controls or administrative controls whenever feasible." Engineering controls include: dust suppression, substitution and ventilation. When ventilation is used, ventilation systems must be inspected on a regular basis. Administrative controls include job rotation, which reduces time exposed to the hazard. When such controls are not feasible, personal protective equipment (PPE) or other measures must be used to keep employee exposure below PEL.
AIR MONITORING It is the employer's responsibility to first determine whether exposure exists at any level, and then determine what the exposure level may be. This need may be determined by:
knowledge of the presence of crystalline silica in the workplace; reason to suspect that airborne concentrations of crystalline silica exist; observations indicating exposure to crystalline silica such as employee complaints or symptoms; any change in production or processes that may result in an increase of airborne concentrations of crystalline silica; results of personal air monitoring of the employee breathing zone. Note: Total dust samples are typically used in area sampling. To determine employee exposure, respirable sampling must be performed. This sampling separates (by size) SiO[2] particles capable of entering the lungs and causing silicosis.
PERSONAL HYGIENE FACILITIES AND PRACTICES To adequately protect workers, several provisions must be taken into account, and the following types of facilities provided:
handwash facilities; lavatories stocked with soap, towels; showers; change areas with provisions for storing clean and contaminated clothing; separate eating/lunch facilities located away from the exposure. In addition, work clothes may not be cleaned by blowing or shaking. They must be vacuumed with a high efficiency particulate air filter (HEPA) vacuum before removal.
PERSONAL PROTECtiVE EQUIPMENT
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The employer must provide PPE that protects the eyes and face, head and extremities, hand, foot, hearing, full body and respiratory system. Employers must provide workers with disposable or washable clothes at the worksite. Employees must change into clean clothes before leaving the worksite.
RESPIRATORY PROTECTION Based on best management practice, respiratory protection is to be used only after all other feasible engineering and administrative controls have been exhausted. When respirators are used, employers must establish a respiratory protection program as outlined in 29 CFR 1910.134, 29 CFR 1926.103 and NIOSH's "Guide to Respiratory Protection."
MEDICAL SURVEILLANCE NIOSH recommends medical examinations be made available to employees who may be exposed to crystalline before job placement (and at least every three months thereafter). Exams should be performed under the supervision of a licensed physician, be conducted during normal working hours and at no cost to employees. Exams should include a complete medical and occupational history; an annual chest xray; pulmonary function tests; and an annual evaluation for tuberculosis.
TRAINING Training is required by 29 CFR 1926.21 (Safety Training and Education) and 29 CFR 1926.59 (Hazard Communication). It must include:
instruction in the recognition and avoidance of unsafe conditions concerning crystalline silica; information concerning potential physical/health hazards and adverse health effects of crystalline silica; information on personal hygiene and required personal protective measures; details of the employer's hazard communication and crystalline silica programs, including information on labeling and material safety data sheets; instruction on the employer's PPE and respiratory protection programs, including selection, inspection, use and maintenance of respirators. HOUSEKEEPING To minimize the spread of silica, consistent housekeeping is required. Here are a few (cited) examples.
Exposed surfaces must be maintained free of the accumulation of silica dust. Dry sweeping and use of compressed air for cleaning work surfaces is strictly prohibited. Vacuum surfaces and clothing only with a HEPAfilterequipped vacuum. SUMMARY Silica meets the criteria of the priority planning process. Crystalline silica represents a serious health hazard, as indicated by continuing deaths from accelerated silicosis. Furthermore, recent studies demonstrate a statistically significant increase in lung cancer among silicaexposed workers. Studies indicate that some workers are still exposed to high levels of silica, and suggest that the current OSHA standard is insufficient to protect against silicosis.
It is not clearly defined why a different testing procedure exists for measuring (estimating) the respirable crystalline silica within the construction industry. In contrast, general industry has a method for actually measuring personal respirable dust from the worker's breathing zone. As with any performancebased standard, the language of the proposed rule should focus on the prevention of silicosis, thereby targeting facilities or activities that pose a reasonable chance of exposure above PEL. (Note: The presence of silica should be the issue and trigger point for testing.)
In the authors' opinion, OSHA should provide more guidance (to employers) concerning minimal requirements for silicaspecific safety and health programs. This guidance should combine the
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requirements of the cited standards taken from Appendix B in the SEE Placing combined requirements into a performancebased standard (specific to crystalline silica) would clarify the agency's requirements.
More information on this issue is available on OSHA's website: www.OSHASLC/stc/SilicaCrystalline/index.html.
REFERENCES Clayton, George D. and Florence E. Clayton. Patty's Industrial Hygiene and Toxicology, General Principles. 4th ed. Vol 1. New York: John Wiley & Sons Inc., 1991.
"Crystalline Silica." OSHA Compliance Directive CPL 22.7. Washington, DC: Dept. of Labor, Occupational Safety and Health Administration, 1978.
"OSHA Launches A National Special Emphasis Program to Reduce Worker Silica Dust Exposures that Can Cause Silicosis." OSHA News Release, May 1996.
"Preventing Silicosis and Deaths from Sandblasting." NIOSH Alert, Publication No. 92102. Washington, DC: National Institute for Occupational Safety and Health, 1992.
"Preventing Silicosis & Deaths in Construction Workers." NIOSH Alert, Publication No. 96112. Washington, DC: National Institute for Occupational Safety and Health, 1996.
"Preventing Silicosis and Deaths in Rock Drillers." NIOSH Alert, Publication No. 92107. Washington, DC: National Institute for Occupational Safety and Health, 1992.
"Silica Dust Exposure Can Cause Silicosis." OSHA Fact Sheet. Washington, DC: Dept. of Labor, Occupational Safety and Health Administration, 1996.
"Silicosis: Cluster in Sandblasters Texas and Occupational Surveillance for Silicosis." Atlanta: Centers for Disease Control and Prevention, 1990.
"WorkRelated Lung Disease Surveillance Report, 1994." DHHS (NIOSH) No. 94120. Atlanta: Centers for Disease Control and Prevention, 1994.
TABLE 1
OSHA STANDARD REFERENCE
1926.21 Safety Training and Education 1926.23 First Aid and Medical Attention 1926.27, 1926.51 Sanitation (hygiene) 1926.28 Personal Protective Equipment 1926.100 Head Protection 1926.101 Hearing Protection 1926.102 Eye and Face Protection 1926.103, 1910.134 Respiratory Protection 1926.55 Gases, Vapors, Fumes, Dust and Mists (PELs) 1926.57 Ventilation 1926.59, 1910.1200 Hazard communication ~~~~~~~~
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By James E. Roughton
James E. Roughton, CSP, CHMM, is district health and safety manager, Atlantic Coast, Florida Region, for Fluor Daniel GTI, Marietta, GA. Roughton is a member of ASSE's Georgia Chapter.
By John C. Pierdomenico
John C. Pierdomenico, CIH, is a health and safety manager for Fluor Daniel GTI, based in Marlton, NJ. He is a professional member of ASSE's Philadelphia Chapter, a member of the American Industrial Hygiene Assn. (AIHA) and a member of AIHA's Gas and Vapor Detection Systems Committee. He holds a B.S. in Environmental Resource Management and an M.S. in Environmental Health.
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