No day at the beach: the Occupational Safety and Health Administration (OSHA) has been threatening to lessen exposure to the respirable crystalline silica in metalcasting sand for more than 10 years. Now, they are finally doing something about it.

One thing is certain: most metalcasting facilities cannot operate without silica sand But what exposure to employees can be harmful, and to what extent can it be controlled?

This question takes center stage in a drama that has been playing out since 1995, when OSHA prioritized controlling exposure to respirable crystalline silica, which is found in varying amounts in metalcasting sand. At the time, the question had been answered in such a way that satisfied many of the actors involved: The current permissible exposure limit (PEL) for respirable crystalline silica (also called quartz) was set according to a mathematical formula: 10 divided by the percentage of quartz plus two. In other words, very small silica dust had to be held to a certain level on average throughout a workday to control the health risks associated with it. OSHA, however, soon became dissatisfied with that limit.

The parties involved in the ongoing argument use silica-related illness and deaths to determine how well the pollutant has been neutralized. OSHA believes that these are too many. Metalcasters' unions agree.

But metalcasting associations and small business concerns disagree with the interpretation of the numbers, saying that progress has been made in lowering the death toll. The difficulty is in determining who is correct--a task that already has consumed 10 years.

"OSHA has been engaged in the very earliest stages of rulemaking activity for the last couple of years," said Mark Ellis, president of both the National Industrial Sand Association and Industrial Minerals Association of North America. "They are anticipating ramping up [to lower the PEL]. According to the regulatory agenda which came out in April, a health assessment document and a risk assessment document are to be done in a few months. They also will convene a peer review panel to evaluate those documents."

Once the documents have been completed, the regulatory process will be in the home stretch. All that will be left will be finding the right balance between how much exposure to respirable crystalline silica can be a hazard to one's health and how much can be eliminated from the metalcasting environment within reason.

Silica Presents a Risk

Not all silica sand is hazardous to the health. There's no need to go running to the emergency room if you get a mouthful while operating a squeezer. But when crystalline silica particle size is at a certain level and at a high concentration, it is capable of reaching the lungs and inflicting harm.

Three levels of quartz grain size are worth monitoring, each with a different capacity for infiltrating the body. To be inhalable, quartz particles must erode down to less than 0.1 mm (0.004 in.), where they are capable of entering the upper airways. When the grains become smaller than 0.01 mm (0.0004 in.) (thoracic particles), they can enter the throat, and when they are half that size--0.005 mm (0.0002 in.)---they become respirable and capable of penetrating the lung. It is this respirable quartz that can bring about serious illness.

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Respirable crystalline silica has been shown to cause silicosis, which can lead to lung cancer. There were more than 1,000 deaths per year attributed to silicosis at the peak of exposure in the late 1960s, according to the National Institute for Occupational Safety and Health (NIOSH).

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Curbing Silica's Risk

Proponents of the current PEL maintain that much progress has already been made in reducing the number of silica-influenced deaths. NIOSH reports fewer than 200 silicosis-related deaths in the late 1990s.

"The number of silicosis cases is declining, and that indicates past improvements, because there is a latency period," said Thomas Slavin, manager of occupational safety and health at International Truck and Engine Corp., Warrenville, Ill. "You don't see the effect of a reduction right away."

Slavin also said there is evidence (Fig. 3) that exposure levels have declined in recent years, which will result in future silicosis reductions. What's more, this progress is being made despite the fact that less than 70% of metalcasting facilities surveyed have proven compliance.

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"We're seeing this reduction and this improvement even through the industry as a whole is not in compliance," he said. "So if we were to concentrate on just getting into compliance with the current PEL, we should see an even greater decline in the future. The bottom line is, do you need to get the clean cleaner or get the dirty clean? By lowing the PEL, you just get the clean cleaner; you don't focus on the people who are non-compliant."

Regulating Toward Compliance

In addition to the disagreement over how much progress has been made, the establishment of a firm silica sand PEL has been bogged down for a decade due to the nature of the regulatory process.

"The regulatory process is a pursuit of good science and good law coming together to produce a regulation that is necessary for one, just for another and feasible for a third," Ellis said. "It's a bit of art and science combined."

The necessary and just portions of the process define the struggle to determine whether the current PEL is sufficient to reduce the number of silica-related illnesses. The feasibility question complicates things further.

According to Slavin, the feasibility question is threefold, considering economic feasibility, technical feasibility and analytical feasibility.

"It's tough to get to the current level without incurring a large cost," he said, referring to the question of economic feasibility. "That's part of the reason there is so much non-compliance already."

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Slavin also notes that metalcasting facilities will be hit hardest by the economic repercussions of a lowered PEL, as it is a marginal business. While industries like construction will always be around, the smaller metalcasting facilities will simply shut down if the economic burden of compliance becomes too great.

Technical feasibility explores whether it is possible to reach a lower silica sand PEL. The preferred way to do so is to reengineer the guilty metalcasting processes so that they produce fewer crystalline silica particles. Alternatively, improved ventilation can put metalcasting workers at a reduced risk.

There are certain processes, according to Slavin, that can be difficult to reengineer to the point of achieving a lower silica PEL, such as knockoff operations, which are a prime culprit of silicate emissions. In such cases, it can become necessary to use personal protective equipment (PPE) to reduce the risk of silicate exposure. However, in the past, OSHA has preferred that metalcasting facilities use PPEs only as a last resort when reengineering has failed.

The final issue when it comes to compliance is analytical feasibility. Can a lowered PEL be measured?

"If you were to take the permissible exposure limits and drive it down to the limits of detection, then it becomes difficult to analyze the results," Ellis said.

The human eye is capable of seeing a particle as small as 0.075 mm, or about the width of a hair. Detection systems also have their limits, and they almost have been reached. According to Slavin, laboratories currently analyzing the presence of particulate silica are operating at the very edge of reliability. At the existing PEL, laboratory results can deviate from as little as half of the true amount to as much as double. Lowering the PEL would raise that deviation.

The Sands of Time 

The feasibility of metalcasting facilities coming into compliance, in the end, takes a back seat to the health concerns associated with silica exposure, making the balancing act all the more treacherous. And the final act won't be performed until OSHA releases all of its assessment documents. Even then, the process will be drawn out to include public hearings, an open comment period and peer review.

"On the basis of experience, you're looking at a minimum of two years before this is resolved," Ellis said. "And that's speaking at a minimum."

What the PEL?

The primary concern for metalcasting facilities is that the Occupational Safety and Health Administration (OSHA) will lower the permissible exposure level (PEL) to an unreachable number. But that's only one of several possibilities.

Lowering the PEt

Even before OSHA decided to focus on the dangers of silica exposure, a small business advisory panel convened in 1993 to discuss the effects of lowering the PEL. As a talking point for the panel, OSHA floated two alternatives to the existing PEL--0.075 mg per cu. m and 0.05 mg per cu. m. According to Mark Ellis, president of both the National Industrial Sand Association and Industrial Minerals Association of North America, the first of those would be a likely reset point if the health assessment document shows that there needs to be a reduction in the PEL. The second, he said, would be very difficult to measure in a real setting.

Changing it Up

Metalcasting facilities may be forced to create "change rooms" for the purpose of localizing the dangers of silica sand. As the name suggests, the rooms would be a place for metalcasters to change clothes and shower off after coming into contact with silica sands. This option would be especially attractive if OSHA's health assessment revealed a silicosis risk for family members of metalcasting facility workers.

Bring the Enforcers

Thomas Slavin, manager of occupational safety and health at International Truck and Engine Corp., Warrenville, Ill., says that more than 30% of metalcasting facilities currently are not in compliance with the current PEL for crystalline silica. He believes that strictly enforcing the existing limit would do more good than lowering it.

Expanded Standard

Slavin also suggests that the standards would benefit from being stretched across the board.

"Right now, the only thing they have is the limit," he said. "There's no requirement for surveillance, medical or testing. If you had a requirement for testing, for example, you'd probably identify a lot of places that were out of compliance and didn't know it. If you had medical screening and a full program, you'd be able to protect people even in non-compliance."