Special Emphasis Program From: Joseph A.
Dear, Assistant Secretary |
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This memorandum
provides inspection targeting guidance for implementing an OSHA-wide Special Emphasis
Program (SEP) to reduce and eliminate the workplace incidence of silicosis from exposure
to crystalline silica. The policy set forth in this memorandum is effective immediately.
This SEP covers most SIC codes where an exposure to crystalline silica may exist.
Inspections initiated under this SEP shall be scheduled and conducted in accordance with
the provisions in the Field Information Reference Manual (FIRM) and the Revised Field
Operations Manual (FOM). 1,2 Regional Administrators and Area Directors shall
ensure that the procedures established in this memorandum are adhered to in the scheduling
of programmed inspections. Regional Administrators shall also ensure that the State
Consultation Program Managers and the State Plan State Designees in their Regions are
appraised and aware of the contents of this SEP and its required Area Office outreach
initiatives. In all Federal enforcement states, and state plan states which adopt this
program policy, Regional Administrators are to encourage the Consultation Programs' full
cooperation and assistance in this Agency-wide effort. Background information on crystalline silica and silicosis can be found in Appendix A to this document. |
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If the worksite has been inspected within the last 30 days, the results of the inspection shall be considered along with the current worksite observations in determining whether or not an inspection is to be conducted. If the crystalline silica dust generating work was not in progress during the previous visit to the site but is currently in progress the inspection shall be authorized and opened. If the crystalline silica dust generating work was in progress and evaluated during the previous inspection, the inspection will be opened only if apparent serious violations are present or can reasonably be expected at the site. If the worksite has not been inspected within the previous 30 days, an inspection shall be conducted unless it is apparent that workers are not exposed to crystalline silica dust. Documentation of the events leading up to the observation shall be maintained by the Area Office in case of a denial of entry.
The following is a list of elements which may be included in an effective program [Note: In a facility where exposures are below the permissible exposure limit, CSHOs, for education and information purposes, should make the employer aware of elements that should be included in an effective crystalline silica control program in order to provide employees at the establishment protection from possible crystalline silica over exposure(s)]:
*Required by specific OSHA standards if an overexposure to crystalline silica exists.
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Whenever a visit is
made in response to this SEP, Consultation Request, and/or Visit forms are to be completed
as follows:
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Full Service Program SupportEach Area Office/Region is encouraged
to develop outreach programs that will support the enforcement effort. Such programs could
include letters to employers, professional associations, the Associated General
Contractors (AGC), local unions, Associated Builders and Contractors, local safety
councils, apprenticeship programs, local hospitals and occupational health clinics, and/or
other industry employer organizations that work with or potentially generate crystalline
silica dust. Speeches, training sessions, and/or news releases through the local news
papers, safety councils and/or industrial hygiene organizations can provide another avenue
for dissemination of information. A generalized crystalline silica/SEP news release will
be prepared by the National Office and made available to each Region.
All OSHA Consultation Program offices will be provided with a copy of the SEP memorandum. In those states which are participating in the program, Regional Administrators shall ensure the coordination between Area Directors and the State Consultation Program manager to encourage their assistance in outreach efforts in support of this program. Existing local silica/silicosis expertise within state Consultation program office may provide valuable assistance to the Area Office staff in their various outreach efforts. Consultation projects may also have already developed or have available to them written, audio visual, or materials in other formats on working safely with silica and/or worker safety and health training materials that may be helpful to the Area Office. State Consultation projects are provided specific instruction in this document for coding consultative visits made for requests for assistance in response to this SEP. Requests for Consultative visits from employers as a result of OSHA's Silicosis SEP are to be given priority over other visit requests, as appropriate. The Office of Health Compliance Assistance in conjunction with the OSHA Training Institute will develop crystalline silica related information and training materials. This information will be made available to the Regional Offices for distribution to their respective field offices. Area Offices are encouraged to develop a list of industries and contractors involved in crystalline silica related work and potential exposures. Once the list has been generated, each entry can be contacted (if resources permit) in writing and provided with a copy of this memorandum and general information available about crystalline silica. To assist the Agency in outreach, Area and Regional Offices through the Silica SEP Coordinator should be compiling a list of frequently asked questions (FAQs) that are received a long with their full responses. These FAQs would then be periodically forwarded to the Office of Health Compliance Assistance. The FAQs could include questions like the following:
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Measuring
Agency ImpactEach
Region shall designate an individual as the silica SEP Coordinator. The identified
individual shall coordinate crystalline silica inspection activities and work with the
Office of Health Compliance Assistance to collect and evaluate the effect and success of
this program. Measuring Agency impact can be broken down into an interim component and a
final component. In the interim, the Office of Health Compliance Assistance will collect
and evaluate IMIS data through coding on the OSHA-1 for this SEP. In the long-term, the
Regional Silica Coordinator, in conjunction with the Office of Health Compliance
Assistance, will collect information on the development of new and feasible engineering
and work practice control techniques, and on controls through substitution of silica with
other materials (for example some non-ferrous foundries have found that with equipment
modification they can use olivine sand). They will also collect information on medical
programs implemented, airborne personal monitoring programs in place, examples of silica
control plans or exemplary workplace safety and health programs with effective silica
control program elements, numbers of inspections that were focused, and the like.
Area Offices or the Regions, under this SEP, will need to maintain a file containing abatement information from their inspections and a summary of any medical programs related to silica exposure in effect. The data shall include both recommended and implemented abatement information for the specific type of operation that was evaluated. Such information shall also include a reference to the inspection number. This program will run through Fiscal Year 1997. At the end of Fiscal Year 1997 the program will be regionally evaluated by each Regional Silica Coordinator. A written evaluation will be submitted to the Director of the Office of Health Compliance Assistance discussing the program operation in their respective Regions, the effectiveness, problems encountered, any recommendations for changes or additions to the program, and finally a recommendation on whether or not to continue the program. The Office of Health Compliance Assistance will evaluate these Regional Report and will make a recommendation to the Director of Compliance Programs on whether or not to continue the program. A final report on the program will be prepared by the Office of Health Compliance Assistance evaluating the effectiveness of this SEP. |
Federal
Program ChangeThis
is a federal program change that impacts state programs. The Regional Administrator (RA)
shall ensure that this change is promptly forwarded to each state designee using a format
consistent with the Plan Change Two-way Memorandum in Appendix A, OSHA Instruction STP
2.22A, State Plan Policies and Procedures Manual (SPM). The RA shall explain the content
of this change to the state designees. States are encouraged, but not required, to adopt
an identical or alternative policy. States shall be asked to provide preliminary
notification to the RA within 30 days from the date of this instruction of their intent to
adopt or not to adopt the SEP established by this memorandum. The state shall formally
respond to this change with an indication of its final determination within 70 days in
accordance with paragraph I.1.a.(2).(a). and (b), Chapter III of Part I of the SPM. If the
state adopts identical compliance procedures, the Plan Change Two-way Memorandum plus a
copy of the state's cover memo or directive transmitting these procedures to its field
staff will suffice as the plan supplement. If the state adopts different compliance
procedures, a copy of the procedures shall be provided to the RA within six (6) months
from the date of this memorandum.
In those state plan states where the PEL in construction or maritime is the same as OSHA's (units in MPPCF) the states are urged to follow the procedures spelled out in Appendix F. States are also strongly encouraged to use all the sampling and analytical methods in this memorandum when they evaluate crystalline silica, regardless of whether they adopt the SEP. These procedures are the same as those in the OSHA Technical Manual. As with any complex sampling procedures, states not having the necessary laboratory equipment for the analyses may contact the Salt Lake City Laboratory for assistance. The RA shall review policy, procedures, and instructions issued by the state and monitor their implementation as provided in a performance agreement or through routine monitoring focusing on impact and results. Distribution: National, Regional, and Area Offices |
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Appendix ABackground: Crystalline Silica and Silicosis
Crystalline silica is a ubiquitous substance which is the basic component of sand, quartz and granite rock. 9 Airborne crystalline silica occurs commonly in both the work and non-work environments. Occupational exposure to crystalline silica dust has long been known to produce silicosis, a pneumoconiosis or dust disease of the lung. Activities such as sandblasting, rock drilling, roof bolting, foundry work, stonecutting, drilling, quarrying, brick/block/concrete cutting, gunite operations, lead-based paint encapsulant applications, and tunneling through the earth's crust can create an airborne silica exposure hazard. In addition some recently noted exposures to crystalline silica include the following:
Geologically, quartz is the second most common mineral in the earth's crust. Quartz is readily found in both sedimentary and igneous rocks. Quartz content can vary greatly among different rock types, for example: granite can contain anywhere from 10 to 40 percent quartz; shales have been found to average approximately 22 percent quartz; and sandstones can average almost 70 percent quartz. Silica is a general term for the compound silicon dioxide (SiO2). Silica can be crystalline or amorphous. Different crystalline silica structures exist as polymorphs of silica and include quartz and less common forms such as cristobalite and tridymite. The latter two are less stable than quartz which accounts for the dominance of the quartz form. Quartz can exist as two sub-polymorphs, à-quartz or low quartz, and -quartz or high quartz. Of these two forms, à-quartz is more common as the -quartz is apparently only stable at temperatures above approximately 570 degrees centigrade. Upon cooling, -quartz quickly converts to à-quartz. In the literature, crystalline silica is commonly referred to as silica sand, free-silica, quartz, cristobalite, and tripoli. When diatomaceous earth is subjected to pressure or is processed (calcined) at temperatures above 1000 degrees C some of the amorphous silica is converted to crystalline silica in the form of cristobalite. 11 Recent articles have documented the creation of cristobalite in "after-service" refractive ceramic fiber insulation. 12-14 Amorphous silica has been found to exist in nature as opal, flint, siliceous glass, diatomaceous earth and vitreous silica. 15 Silicosis is one of the world's oldest known occupational diseases with reports dating back to ancient Greece. Since the 1800's, the silicotic health problems associated with crystalline silica dust exposure have been referred to under a variety of common names including: consumption, ganister disease, grinders' asthma, grinders' dust consumption, grinders' rot, grit consumption, masons' disease, miner's asthma, miner's phthisis, potters' rot, sewer disease, stonemason's disease, chalicosis, and shistosis. Silicosis was considered the most serious occupational hazard during the 1930s, and was the focus of major federal, state, and professional attention during this time. 10 The hazard is still present 60+ years later. Crystalline silica is commonly found and used in the following industries:
Perhaps the most familiar use of quartz sand is as an abrasive blasting agent to remove surface coatings prior to repainting or treating. A recent alert published by the National Institute for Occupational Safety and Health (NIOSH) estimates that there are more than one million American workers that are at risk of developing silicosis. Of these workers, NIOSH further estimates that more than 100,000 are employed as sandblasters.16 In the United States, from 1968 through 1990 the total number of deaths where silicosis was reported anywhere on the death certificate was 13,744. Of these, approximately 6,322 listed silicosis as the underlying cause of the death. 17 In this study, deaths in the United States due to silicosis was primarily concentrated in 12 states (California, Colorado, Florida, Illinois, Michigan, New Jersey, New York, Ohio, Pennsylvania, Virginia, West Virginia, and Wisconsin.) The silica-related deaths in these 12 states accounted for 68% of the total silica related deaths in the United States. By industry, construction accounted for 10% of the total silicosis-related deaths.17 Based upon the wide spread occurrence and use of crystalline silica across the major industrial groups (maritime, agriculture, construction, and general industry), and in consideration of the number of silicosis related deaths, the NIOSH estimates for the number of exposed workers, and the health effects of crystalline silica dust exposure (e.g., pulmonary fibrosis, lung and stomach cancer), the Agency is implementing a nationwide special emphasis program to assure worker protection from over exposure to crystalline silica dust. Health Effects of Silica Exposure Inhalation of crystalline silica-containing dusts has been associated with silicosis, chronic obstructive pulmonary disease, bronchitis, collagen vascular diseases, chronic granulomatous infections such as tuberculosis, and lung cancer. In general, aerosols of particulates can be deposited in the lungs. This can produce rapid or slow local tissue damage, eventual disease or physical plugging. Dust containing crystalline silica can cause formation of fibrosis (scar tissue) in the lungs.9 The inhalation of free crystalline silicon dioxide (SiO2) can produce a fibrotic lung disease known as silicosis. Particle size, dust concentration and duration of dust exposure are important factors in determining the attack rate, latency period, incidence, rate of progression and outcome of disease. A higher attack rate and severity of silicosis is seen with heating crystalline silica-containing materials to greater than 800º C to transform SiO2 into tridymite and cristobalite (both of which occur naturally and are also found in synthetic silica preparations). High cristobalite concentration also result from direct conversion of diatomaceous earth following heat and/or pressure and can be found in the superficial layers of refractory brick which have been repeatedly subjected to contact with molten metal. 9 NIOSH has classified three types of silicosis, these include acute, accelerated, and chronic. Acute Health Effects: Intense crystalline silica exposure has resulted in outbreaks of acute silicosis referred to medically as silico-proteinosis or alveolar lipoproteinosis-like silicosis. Initially, crystalline silica particles produce an alveolitis (inflammation in the gas exchange area of the lung) which is characterized by sustained increases in the total number of alveolar cells, including macrophages, lymphocytes and neutrophils. The alveolitis has been found to progress to the characteristic nodular fibrosis of simple silicosis. A rapid increase in the rate of synthesis and deposition of lung collagen has also been seen with the inhalation of crystalline silica particles. The collagen formed is unique to silica-induced lung disease and biochemically different from normal lung collagen.18 Accelerated Health Effects: Accelerated silicosis may occur with more intense exposure over 5 to 15 years. Fibrotic nodules are generally smaller and the massive fibrosis often occurs in the mid-zones in the lungs. Acute and accelerated silicosis have been associated with abrasive blasters. Chronic Health Effects: Chronic silicosis usually takes 20 to 45 years to develop as a result of prolonged exposure to free crystalline silica. Nodular lesions tend to form in the upper lobes. In the simple stage of silicosis, symptoms and impairment of pulmonary function are uncommon. If progressive massive fibrosis (PMF) forms from the coalescence of fibrotic nodules the disease usually progresses, even following removal from exposure. Symptoms of silicosis may not develop for many years. Shortness of breath with exertion is the most common symptom of established silicosis. Cough and expectoration may develop with disease progression, especially in cigarette smokers. Wheezing typically only occurs when conditions such as chronic obstructive bronchitis or asthma are also present. Significant abnormality on a chest x-ray may not be seen until 15 to 20 years of exposure have occurred. When advanced disease and progressive massive fibrosis are present there is distortion of the normal architecture of the lung. Airway obstruction may occur from contraction of the upper lobes of the lung. Emphysematous changes may develop in the lower lobes of the lung.19 Cancer: The issue of crystalline silica exposure and cancer is a complicated one with disagreement in the literature. 20 In worst case, exposure to respirable crystalline silica dust has been associated with lung cancer. 20-26 There also has been the suggestion of stomach cancer associated with ingestion of crystalline silica. 7 The International Agency for Research on Cancer (IARC) in examining the carcinogenesis of crystalline silica has published monographs regarding crystalline silica and some silicates. IARC determined that there is sufficient evidence for carcinogenicity in experimental animals with limited evidence for carcinogenicity in humans and has classified silica as a 2B carcinogen. 21 IARC is in the process of revisiting the crystalline silica carcinogen issue based upon recent epidemiological studies. Studies have demonstrated a statistically significant, dose-related increase in lung cancer in several occupationally exposed groups. Winter (1990) observed that the lung cancer risk for pottery workers increased with estimated cumulative exposure to low levels of silica found in potteries. Another study also found that the risk of lung cancer among pottery workers was related to exposure to silica, although the dose-response gradient was not significant (McLaughlin, et al., 1992). An adjustment for possibly confounding exposure to polycyclic aromatic hydrocarbons slightly raised the odds ratios for exposure to silica. This study also analyzed lung cancer risk in tin miners in China and found a significant trend of increasing risk of lung cancer with increasing cumulative respirable silica exposure. A significant dose-response relationship between death from lung cancer and silica dust particle-years has also been demonstrated for South African gold miners (Hnizdo and Sluis-Cremer, 1991). In this study a synergistic effect on lung cancer risk was found for silica exposure and smoking. Lung cancer risk among workers in the diatomaceous earth industry has been studied by Checkoway, et al. (1993). Results showed increasing risk gradients for lung cancer with cumulative exposure to crystalline silica. The authors felt that this finding indicated a causal relation. Several studies have demonstrated a relationship between the degree of silicosis disability and risk for lung cancer (Goldsmith, 1994). Since severity of silicosis reflects silica exposure, this may also indicate a dose-response relationship for silica exposure and lung cancer (Checkoway, 1993). For additional information please refer to references No. 22-26. Note:
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Appendix
BSIC Codes where
overexposures to crystalline silica dust have been documented 22
SIC Codes where sampling has been conducted for crystalline silica dust during the previous three years and overexposures were not found.
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Medical protocol
recommendations for exposure to crystalline silica 28-48: |
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Appendix DThe following list of standards includes those standards, that may, under appropriate inspection conditions be cited for crystalline silica overexposure under this SEP. The standards listed below are for general industry, maritime, and construction standards. | ||||||||||||||||||||||||||||||||||||||||||||||||
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Appendix
ESample Calculation for
a mixture of crystalline silica: 8 Two consecutive samples from the same employee taken from a combined exposure to crystalline silica dusts have the following results: |
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ND =
Non Detected Calculation of the TWA from the sampling and analytical data:
Step No. 2: Calculate the PEL for the mixture (use the formula in the OSHA Technical manual
Appendix I-1.5) Step No. 3: Calculate the employee's exposure to respirable dust Step No. 4: Adjust (where necessary) for sampling period less than 8-hours. Assume a zero
exposure time for the sampling period remaining. Step No. 5: Calculate the Severity of the exposure: |
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Appendix FPermissible Exposure Limits for Construction and
Maritime: OSHA's silica standards, promulgated pursuant to section 6(a) of the OSH Act, adopted the identical 1968 (General Industry) and 1970 (construction and maritime) ACGIH TLVs, which were expressed in terms of mppcf, but contained a notification that ACGIH intended to begin to express the silica TLV in gravimetric (mg/m3) terms. 49-51 The 1968 and 1970 TLV tables therefore included two formulas. Formula No. 1: PEL = 250/((% quartz) +5) mppc, or The 1968 and 1970 TLV documentation described the advantages of the newer gravimetric sampling method, which yields results expressed mg/m3, over the impinger sampling method, which yields results expressed in mppcf. 49-51 These advantages include the gravimetric sampling method's ability to account for the particle size and respirability of collected dust, and the facts that only a single sample need be collected to determine both the quartz content and the concentration of the dust and that the samples do not need to be analyzed within 24 hours. Moreover, the results are likely to be more accurate because, unlike impinger samples, they will not be affected by the possible agglomeration of collected dust during processing. The documentation also explained that the two formulas provided equivalent limits, and stated ACGIH's intent to drop the mppcf formula entirely from future TLV editions. 49-51 Beginning in 1972, silica TLVs have been expressed exclusively in gravimetric terms. 51 ACGIH made clear that the purpose of this change was to take account of improved sampling and analytical procedures, and not to change the TLV in any way: "The impinger method requiring a counting procedure for evaluating relative dustiness, although extremely valuable in judging dust reduction, falls short of the ideal in relevance to health hazard, in simplicity, in reproducibility, and in unit cost. By the use of size-selective (cyclones) sampling devices, a fraction of dust may be collected which is capable of penetrating to the gas-exchange portion of the lung, where long-term retention occurs. The concentration of airborne quartz in this size fraction should relate more closely to the degree of health hazard. Mass methods also have advantages in reproducibility, lower cost, and simplicity. Data on long-term quartz exposures and their effects, using respirable mass measurements of dust, are not yet available. However, comparisons of impinger-count concentration and respirable-mass concentration show that the 9-10 MPPCF of granite dust suggested by Russell contains 0.1 mg/m3 of respirable quartz.52 The formula, TLV = 10/(%respirable quartz) mg/m3 generalizes this relationship to all percentages of quartz in respirable dust. If the TLV were used only for dust containing at least 5% quartz, the above TLV formula would be satisfactory, but to prevent excessively high respirable dust concentrations when the fraction of quartz in the dust is less than 5%, a constant has been added in the denominator, as with the counting TLV, giving the formula, TLV = 10/(% respirable quartz + 2) mg/m3. The additive constant "2" limits the concentration of respirable dust with <1% quartz to 5 mg/m3. The above TLV has been demonstrated to give evaluations comparable to the impinger method in foundry dust exposures (emphasis added).53 Where agglomerates are a factor, the results by the respirable mass method are more closely related to the hazard." 51 |
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OSHA's
general industry standard, 29 C.F.R. 1910.1000, adopted in 1971, included both formulas as
equivalent exposure limits. The construction and maritime standards, adopted in 1974,
however, included only the mppcf formula. No reason was given for this distinction. In
fact, OSHA's 1971 adoption of both formulas in its general industry standard makes clear
the agency's agreement with ACGIH's position that the two formulas are substantively
equivalent. Since the PELs were adopted, the impinger sampling method has been rendered obsolete by gravimetric sampling. OSHA is not aware of any government agencies or employers in this country that are currently using impinger sampling to assess worker exposure to dust containing crystalline silica, and impinger samples are generally recognized as being less reliable than gravimetric samples. OSHA has determined that sampling procedures in the construction and maritime industries should be the same as in general industry, and that the mppcf PELs in 29 C.F.R. 1915.1000 and 1926.55(a) are equivalent to the mg/m3 PEL in 29 C.F.R. 1910.1000. |
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References Related
to the SEP |