SESSION 1 - September 15, 1999
8:30 a.m.-12:00 p.m.


The format of the stakeholder sessions followed the questions in a stakeholder document that is also available on the Web page. There were four general areas of discussion: scope, controlling exposures to crystalline silica, monitoring and sampling, and health screening and surveillance.


The OSHA panel stated that it was considering covering general industry, construction, and maritime but not agriculture, and was considering covering all forms of crystalline silica. OSHA emphasized that no decisions had been made yet, and all issues were still open.

Stakeholders from the construction and maritime industries requested separate standards for the construction and maritime industries.

The OSHA panel replied:
  • The Agency does not, at this time, plan to do separate rulemakings for construction and maritime.
  • It is considering developing one standard and tiering requirements for construction and maritime.
  • Separate rulemakings would delay effective protection for employees for years in several industries with very high risks.

One stakeholder asked whether the railroad industry will be included in general industry, and said that OSHA should address the jurisdiction of railroads in the preamble.

An MSHA representative said that MSHA does not anticipate proposing a comprehensive rulemaking with a new PEL, but does intend to make sure its approach and programs are not inconsistent with OSHA's rulemaking activities.

Foundry representatives stated:
  • There is great variation in that industry with respect to the level of mechanization, the sizes of companies, and their abilities to protect workers.
  • A foundry that casts single pieces weighing several tons has exposure control problems very different from those of a new plant with automation that produces high volumes of the same casting.
  • One foundry representative noted that his foundry employed about 400 workers, and that 99 percent of all production workers had some exposure to silica. One-quarter of their exposure samples had results at or above the current PEL.
  • The foundry representatives said that setting an action level would result in more workers having to be trained.

The OSHA panel responded:
  • Action levels are traditional in OSHA health standards and they are generally favored by employers.
  • More workers would be protected if we include an action level.
  • The Agency has not made any decisions yet regarding an action level.

A bentonite clay industry stakeholder said:
  • His company sells silica products to users covered by OSHA.
  • Pet care products manufacturers and industrial coating companies will also be interested in how OSHA might regulate treated silica products.
  • Would OSHA include clay-coated products?
  • How will OSHA consider the bioactivity and toxicology evidence?

The OSHA panel responded: It would consider the evidence on treated products and the unique situations in different industries; however, it would be impractical to attempt to publish a rule for every industry.

A union stakeholder addressed the issue of having separate standards for the construction and maritime industries, stating that those industries do have unique circumstances, but addressing these circumstances should not slow down rulemaking. Also, he expressed concern about excluding encapsulated products or other substances from coverage under the standard.

A NIOSH representative stated: There is an absence of epidemiological data on clay or encapsulated materials. The lab data is interesting, but there is not enough conclusive evidence to exclude treated or encapsulated products at this time.

A steel casting stakeholder asked if there were any data on the link between a lower PEL and the corresponding silicosis rate. Also, could the current cases of silicosis be caused by past exposures above the current PEL? A representative from the medical profession responded that he'd seen cases of silicosis even though follow-up investigation had indicated that the exposures were at or below the current PEL.

The OSHA panel stated:
  • Preliminary risk assessments for silicosis and lung cancer are in progress at the Agency.
  • A preliminary view of the data suggests there may be an excess risk at the current PEL.
  • The NIOSH Criteria Document recommends 50 micrograms per cubic meter (50 ug/m3) as a PEL.
  • There are published epidemiology studies of workers that show excess risk.

A tile industry representative said that X rays may themselves pose a risk, with a case of lung cancer occurring for every 1,000 X rays. X rays may not be effective in conclusively identifying a disease, and they can be harmful and expensive, he said. The OSHA panel responded saying that this issue will be discussed more fully in the section on screening and surveillance.

The OSHA panel posed the question: In which operations are exposures the greatest?

A quarry representative responded, saying that in processing rock for many products, the rock has to be dried before it can go into an oven or a mill. Wet methods cannot be used. Also, people have to clean out bag houses. These are operations with potential for high exposure.

A shipyard representative said exposures are high in that industry, and there are many unique situations. Sandblasting is performed in small, enclosed areas, for example.


The OSHA panel began the discussion by asking a series of questions about engineering and work practice controls:
  • To what extent are wet methods and ventilation effective?
  • To what extent should we specify controls in a regulation?
  • How should we deal with regulated areas?
  • How should we handle abrasive blasting situations?
  • What are your comments on blowing down and using compressed air?
  • How should hygiene facilities, training, and specific work practices be handled?

A physician said: Open abrasive blasting is a very high-risk operation even when respirators are used. Abrasives with less than one percent silica or non-silica substitutes should be used.

The OSHA panel asked: What would be the effect of a prohibition on the use of compressed air?

A quarry representative stated that generally the use of compressed air is avoided. Instead, that company employs scrapers on conveyors; however, this leads to high maintenance costs, so compressed air is still sometimes used.

A representative from the foundry industry said:
  • Compressed air is usually prohibited, with the exception of its use to clean molds where complete removal of debris is critical to achieving a quality mold.
  • Vacuuming does not work in sand molding; the molds must be blown out. They use lower air pressures for this operation.
  • Local exhaust ventilation can be used in the general area, but compressed air is still needed to clean the molds.
  • Because housekeeping exposures are usually intermittent, perhaps compressed air can be used intermittently when combined with administrative controls.

Another foundry representative reported that use of compressed air for cleaning is common because it is not possible to use vacuums in many operations.

A steel casting representative pointed out that dust collects overhead in equipment and needs to be blown off periodically. Buildings are usually open frame types; they blow down on Saturdays (when fewer workers are present), otherwise dust builds up on the rafters and trickles down into employees' breathing zones.

The OSHA panel asked stakeholders: What are some details or specifics of the industry operations where vacuuming is not feasible, and where local exhaust cannot be used?

Stakeholders answered:
  • Road and highway contractors use compressed air to blow out joints in bridges.
  • In heavy equipment cabs there are 30-90 nooks and crannies in which dust accumulates and trickles down.
  • They also blow dust from cabs using compressed air on a Saturday, when fewer workers are present.

A major industry trade organization representative asked that the standard allow for a combination of respiratory protection and engineering controls. He said it will be especially important for the Agency to clearly state where--and what--engineering controls are necessary.

The OSHA panel responded: The Agency would clarify what is feasible, but, as a rule, follows the hierarchy of controls, which is to use engineering and work practice controls to achieve the PEL, supplemented by personal protective equipment when necessary.

A steel casting representative said for large casting processes, OSHA Compliance personnel have previously allowed respirators, but now insist on engineering controls. He stated further:
  • The cost of engineering solutions can be exorbitant.
  • Ventilation controls on tools do not always work.
  • OSHA inspections should focus not only on where operators work, but also how fast they work. Their rate of work could affect overexposure.

A union stakeholder supported OSHA's reliance on the hierarchy of controls. He asked:
  • Would there be task-based overexposure categories as OSHA had used in the Lead in Construction standard?
  • Would compressed air be prohibited even if exposures are lower than the PEL?
  • What silica content would trigger a compressed air prohibition?

The OSHA panel replied: The use of compressed air usually generates very high exposures, and OSHA needs to learn more about the situations and exposures to make further determinations about those questions.

A construction stakeholder stated that stonemasons can use water to suppress dust 99 percent of the time, but sometimes they have to cut stone dry. When dry cutting is necessary, wrapping the stone in plastic can reduce exposures. Another stakeholder responded that, in some situations, the cutter may be safe, but others downwind or nearby may be exposed.

The OSHA panel said that a presumption of overexposure is being considered for specific tasks. In such tasks, where an exposure assessment or monitoring is not performed, interim control measures would be required. Unless exposure assessment or monitoring showed otherwise, the assumption would be that overexposure had occurred. OSHA asked the stakeholders whether this would be a good regulatory approach.

A ceramic tile representative reported that schools for tile setters teach safe practices, but the industry has problems getting the tile setters to attend the school. He noted that retraining employees is expensive, and he recommended publishing literature for employers and employees.

A quarry tile manufacturer provided the following information: Quarry tile made with clay contains low levels of silica. Tiles are made with water and pressed dust. Short-term exposures exist while loading clay. Exhaust ventilation is used in manufacturing with air exhausted to bag houses. Exposure in manufacturing occurs in loading mills and during cutting. There is some risk of exposure during installation of ceramic tile.

One stakeholder noted that in highway repair:
  • Enclosure, such as wrapping the work area in plastic while cutting, is not feasible.
  • Wet methods are better, but may not be permitted, or feasible, in winter. For example, during bridge deck repairs, it is unsafe to have water dripping off bridges onto roads below and forming ice.
  • The use of water during drought conditions is undesirable.

The OSHA panel asked what the appropriate measures were to minimize contamination in lunch rooms and changing facilities.

Stakeholders asked if OSHA had data on exposure to silica in lunchrooms, and why that might constitute a hazard. Is the route of exposure ingestion or dermal? The OSHA panel responded that there are studies in the scientific literature showing there had been an increase in gastrointestinal cancer associated with exposure to silica. The Agency provided this reference:

  1. Xu, Z., et al. 1996. Cancer risk among iron and steel workers in Anshan, China. Part II. Case-control studies of lung and stomach cancer. Am. J. Ind. Med., 30, 7-15.

The OSHA panel explained that any concern about ingestion of silica is secondary to inhalation exposures.


The OSHA panel said that exposure assessment is required in other single-substance standards and would likely be required for silica also. Assessment identifies operations, jobs, and processes in need of better exposure controls, and it provides employees with knowledge of their exposures and associated health risks.

The OSHA panel asked about exposure assessment strategies as well as sampling and analytical methods as follows:
  • Who performs monitoring?
  • How often is monitoring performed?
  • What have your experiences been regarding monitoring?
  • Should an action level trigger for exposure assessment or monitoring be included in the rule?
  • How might exposure assessment be implemented on construction sites?

Foundry representatives answered:
  • Consultants and workers' compensation insurance carriers perform industrial hygiene monitoring.
  • Sampling is performed twice a year in new installations and in areas where overexposure occurred in the past.
  • An action level of one-half the PEL is acceptable.
  • College-educated safety managers are trained to oversee monitoring. They have tried to get these safety managers to actually perform the monitoring, but the managers are too busy and often postpone it.
  • An individual with a college degree could be trained to perform sampling.
  • Whitewater University in Wisconsin is a school that conducts training.
  • Sampling equipment costs $1,600. The total cost of a sample is $154. Consultants will charge $600 for one test.
  • The sampling pump can be placed inside the respirator, on the lapel, or in a general work area.

A union representative supported an action level of 50 percent of the PEL, but wondered if the currently available analytical method could adequately measure an action level that is sufficiently protective of workers' health, i.e., below significant risk level.

A representative from the masonry industry noted that there are problems in the analytical method for crystalline silica.
  • There is a great deal of interlaboratory variability in analyzing silica samples.
  • There will be a new Proficiency Analytical Testing (PAT) study of the 80 labs that will show the latest information about how the labs compare.
  • Some labs are following protocols that should be recommended for all labs.
  • The reproducibility of results between labs has been poor.
  • The Agency should demonstrate improvement of the sampling and analytical methods before proposing a new standard.

A stakeholder asked:
  • Will OSHA release data on appropriate testing?
  • What about the status and release of analytical methods so that experts can review the methods?

The OSHA panel answered:
  • Information about methods can be obtained from the American Industrial Hygiene Association (AIHA) web site. AIHA has lab accreditation process recommendations. AIHA conducts site visits every three years to accredit labs to review analytical procedures.
  • NIOSH has published its analytical procedures.
  • The agencies have ongoing discussions with the National Institute of Standards and Technology (NIST) regarding the availability of silica reference samples.
  • The labs use different levels of standardization and have published their methods.
  • OSHA is considering conducting a round-robin testing protocol among labs that perform silica analysis.

The OSHA panel said it would not necessarily hold off publishing a proposal until all work on analytical methods was complete. The Agency said that there is a great deal of activity in the area of analytical methods that will be concurrent with the Agency's rulemaking efforts. The Agency believes that the interlab variability can be greatly reduced.

One stakeholder stated that quartz sampling on bentonite:
  • Yields different results from the same place and same time.
  • Analysis of ten different samples can yield ten different results.

A physician was concerned that many small employers have no exposure monitoring program. He stated that exposure assessment lets one know how well engineering controls are working.

A stakeholder from construction asked if OSHA would provide objective data or allow its use, and noted that OSHA has been reluctant to permit use of objective data for its Lead (Pb) standard.

The OSHA panel replied:
  • The Agency must look hard at objective data. The Agency would consider allowing historical and objective data, but wants to establish appropriate criteria for their use; the Agency asked stakeholders for ideas for such criteria.
  • It is the employer's role to evaluate how historical and objective data apply to specific employer's workplaces and conditions.
  • OSHA itself does not provide objective data.

A representative from the transportation construction industry reported that:
  • Health screening costs $150 per employee.
  • For exposure monitoring, consultants charge $75/hour for exposure assessment, with an 8-hour minimum. Three days of sampling would cost about $5,400.
  • Those consultants charge double the field time for report writing of the exposure assessment.
  • These costs would be difficult for small businesses to absorb.


The OSHA panel explained that health screening of some sort needed to be included in the standard because health problems should be identified at the earliest point. Chest X rays and questionnaires are primary means of screening. The OSHA panel asked:
  • How could screening be encouraged?
  • What discourages screening?
  • Should OSHA require that employers report positive findings of silicosis to NIOSH?
  • What would be the effect on industry?
  • OSHA is also concerned with the issue of Medical Removal Protection (MRP). Does your industry have an MRP policy?

One stakeholder questioned whether clinics to perform the required health screening, and readers to evaluate the X rays are available.

A physician stakeholder stated that a baseline screening was needed prior to job placement and that:
  • The number of years of exposure should not be the sole determinant of how often workers are provided chest X rays.
  • Given the latency of silicosis, there may be effects from early and low exposures that can be detected by health screening.
  • For example, employees who are now working in an area that is below an action level would not normally be screened, but might actually need screening to detect the effects of silica-related disease.

A representative from a state agency stated there is no evidence of acute or accelerated silicosis at levels below 100 ug/m3. Giving yearly X rays increases the risk of radiation exposure.

A representative from the State of North Carolina said that this state requires X rays every 24 months in the dusty trades, and also, workers are encouraged to participate in screening when silica-related disease is compensated under Workers' Compensation. A determination that these employees have silicosis or silica-related disease permits re-assignment to a low-exposure job.

A steel casting foundry representative stated that:
  • Participating in screening was a condition of employment in his organization.
  • They do baseline screening: questionnaires, pulmonary function tests, and biennial X rays.
  • Employees with signs of disease may be sent to a pulmonologist.
  • They use A and B readers and never had a case of acute or accelerated silicosis. Those who have problems are those heavily exposed.
  • Causation is difficult to establish because of smoking, other contributors, and other employment exposures that contribute to health outcomes. They frequently need more than one opinion.
  • They had one employee who developed silicosis after 5 years, but he had worked in other foundries for almost 30 years.
  • The issue of prior exposure of employees is a difficult one.

The steel foundry representative asked how Medical Removal Protection (MRP) worked. He said:
  • Exposure to silica is not like exposure to lead, after which, as a result of MRP, the blood lead level goes down and the person can return to work.
  • A spot on an X ray won't go away, so what is the benefit of MRP?

The OSHA panel replied that MRP is used to encourage participation in the medical surveillance program. There may be reasons other than silicosis for which the Health Care Provider (HCP) has recommended medical removal. Even if a worker does not return to work because of MRP, he or she is encouraged to participate in the health screening. Typically, the Agency does put a time limit on MRP.

A union representative was concerned with the consequences of screening. He said that workers are concerned about having continuing employment. They may be reluctant to participate, especially if the participation is triggered by a short-term exposure. He asked if a reading of 1/0 means that a worker is impaired and cannot go back to work.

The OSHA panel asked the stakeholders what they thought the criteria for health screening should be.

A physician said:
  • In the early stages of silicosis the worker is not impaired, but should not be exposed to excess silica dust.
  • Medical science cannot definitively determine rates of progression of silicosis as a function of exposures. Thus, it cannot determine at what levels workers with early signs of silicosis can continue to work. A worker can have a 1/0 evaluation of a chest X ray with normal lung function.
  • X rays should be used in combination with other tests for health screening.
  • Lung function tests are worthless for silicosis. The tests tell only that there are a lot of smokers. It is common to find evidence on an X ray before there is any detectable lung function change.
  • Tuberculosis was a problem in silicotic workers at one time. We do not know of any evidence of increased TB at levels below the OSHA PEL or NIOSH REL.
  • Therefore, why should there be TB screening?

A stakeholder stated:
  • That one percent of his company's workforce has radiological evidence of silicosis from prior employers. These workers are put in jobs where exposure is less than half the current PEL.
  • What level of exposure will be acceptable for those on MRP if it is determined that there is residual risk?
  • If the PEL is lower, and there remains risk below the PEL or the action level, the availability of low exposure jobs will be fewer for MRP.

A specialist in occupational medicine, concerning the issue of multiple physician review, supported the provision of second opinions. He said other diseases mimic silicosis, such as histoplasmosis, and a 1/0 reading is not a diagnosis of silicosis.

A union representative from the boiler makers industry stated that workers have a right to a second opinion, and reiterated that it is important to have job security. He questioned how health screening could be forced upon employees.

A physician answered that it is standard medical practice for anyone with TB to have skin tests and get treatment. TB makes one more vulnerable to silicosis; thus, a TB test is valuable.

The union representative stated that workers are reluctant to screen. They do not want to know of any illness unless they have symptoms. Also, they fear job loss.

A representative from an industry organization suggested a scientific symposium on screening and surveillance. The OSHA panel replied that the Agency had been considering holding such a symposium.

The union representative urged that mandatory screening be accompanied by job protection.

Regarding reporting positive silicosis cases to NIOSH, a steel foundry representative was against new reporting requirements.

The OSHA panel stated that the NIOSH SENSOR Program was successful in identifying cases of silicosis, and said that it was important to obtain information about the frequency and severity of new cases. To recognize the trends, reporting to a central place is needed.

A NIOSH representative agreed that there is a need to identify where the trouble spots are. For example, there was a case of a 21-year old worker with silicosis in Indiana, which has a reporting system, but the state has no record of the case, so the worker could not be followed. It would be helpful if one were able to track the ages of the cases, and the industries of the workers.

A union representative remarked that we know so little about the disease nationally, and that it would be good to have an accumulation of data. However, there is an issue of employee privacy to resolve.

An industry attorney thought that workers might be unhappy if their records were sent to OSHA's National Office. If OSHA does not have money for surveys, the Agency should not burden industry with having to conduct them.

The union representative said the B readers could be asked to report instead of employers having to report.

A physician commented: We hope they report; we cannot force them.

A Department of Transportation representative pointed out that they are already required to report silicosis cases, so there is no problem sharing data with NIOSH. With an aggressive training program we can increase the screening and surveillance program.


At the end of the session, stakeholders were invited to comment on issues they considered important.

A metal casting representative, concerned about the expense of engineering controls, said:
  • One could install a dust collection containment system for a half a million dollars and still not be able to lower exposures to meet OSHA's requirements.
  • With a lower PEL, more workers would have to wear respirators.
  • Increased use of respirators could make it harder to find labor in a tight market.
  • Lowering the PEL might be beneficial from a health effects standpoint, but with a low budget, highly competitive industry jobs might be eliminated as business is impacted.
  • The employees they do find may not readily accept wearing respirators all day.
  • The foundry industry is losing markets to foreign competitors. It is a highly competitive, low-margin industry.
  • This individual had worked for seven foundries in his career and reported that today, three of them are no longer in business.

The OSHA panel responded by saying that these issues would be addressed in the economic impact and feasibility studies that are conducted by the Agency as part of the rulemaking process, and said that it was going to continue discussions with stakeholders on these and other issues in the future.

The metal casting representative said:
  • A lower PEL would not reduce cases of silicosis.
  • Instead, better compliance with the current PEL together with ancillary provisions would reduce silicosis.
  • How could one compare the higher exposures of the past to lower exposures of today?
  • He submitted that it is better to monitor and establish controls at the current PEL.
  • Lowering the PEL would place an enormous burden on employers without firm evidence that it would help.
  • Regular monitoring, X rays, and better engineering controls will work to protect employees.
  • Health studies won't justify lowering the PEL.
  • With a full program and good enforcement, silicosis can be eliminated.

The OSHA panel concluded that devoting a meeting to health screening and surveillance would be a good idea. The Agency is also intending to hold another round of stakeholder meetings.