Proposed Stricter OSHA Regulations on Airborne Silica Exposure Seem Needless

The U.S. Department of Labor’s Occupational Safety and Health Administration (OSHA) is soon set to release new exposure limits to air-borne silica dust. The rulemaking has been in the works for about three years with a final rule scheduled to be announced this year. The silica industry is not enthused.

Silica dust is known to cause respiratory illnesses (e.g., silicosis, lung cancer, other airways diseases) that may contribute to or lead directly to death when it is breathed in high enough concentrations over long enough time periods.

OSHA explains that exposure to respirable silica “occurs in operations involving cutting, sawing, drilling and crushing of concrete, brick, block and other stone products and in operations using sand products, such as in glass manufacturing, foundries and sand blasting.”

OSHA’s proposal, generally, is to lower the existing permissible exposure limits (adopted in 1971) by about 50%, dropping them from around 0.1mg/m3  to 0.05mg/m3 (specific details here). OSHA explains:

The agency currently enforces 40-year-old permissible exposure limits (PELs) for crystalline silica in general industry, construction and shipyards that are outdated, inconsistent between industries and do not adequately protect worker health. The proposed rule brings protections into the 21st century.

And, as the government likes to claim with all of its regulations, the added restrictions will save lots of lives, and in doing so, will save lots of money:

OSHA estimates that the proposed rule will save nearly 700 lives and prevent 1,600 new cases of silicosis per year once the full effects of the rule are realized.

The proposed rule is estimated to provide average net benefits of about $2.8 to $4.7 billion annually over the next 60 years.

Interestingly, a visit to the Centers for Disease Control in search of deaths from silica inhalation produces this chart graphing silicosis mortality over time. The numbers have dropped considerably over the past 40+ years, and by 2010 had fallen to about 100 or so deaths per year (U.S. residents over the age of 15) attributed to silicosis as either the underlying or contributing cause.

Figure 1. Silicosis: Number of deaths, crude and age-adjusted death rates, U.S. residents age 15 and over, 1968–2010 (Source: CDC).

Figure 1. Silicosis: Number of deaths, crude and age-adjusted death rates, U.S. residents age 15 and over, 1968–2010 (Source: CDC).

The CDC data shows that silicosis deaths have been declining and although the decline has slowed, it continues to drop while under the current OSHA guidelines. And further, the 100 or so deaths that are occurring annually are several times less than the annual number of deaths that OSHA predicts will be saved by the new regulations. That’s a pretty neat trick—the new regs are going to save several times more lives than are actually lost!

This means not only that the OSHA mortality benefits from the new regulations are questionable, but so too must be the economic benefits (as they are tied directly to the mortality savings).

The silica industry isn’t taking this lightly.

They contend that the OSHA mortality projections are based on dose-response relationships that are not truly indicative of what is really going on, for several reasons, primarily that they are based upon poor and inadequate data and analyses.

Dose-response curves used by the federal government are notorious for producing forecasts of a much greater health benefit than actually occurs. For one reason, often, the federal dose-response curves aren’t actually curves at all, but are rather straight lines. Which means that the response is the same for all dosage increments. This allows government regulatory agencies to claim the continually cranking down the exposure limits will continually produce positive health outcomes.

But, more and more research is proving that this is not the case. As the dose gets lower, the response often flattens out (i.e. there is a threshold) or may in fact become positive (low dosages are actually good for you). While this sounds like common sense to most of us (consider sunshine or alcohol), it is a ground-breaking notion in the field. And much of the research on this groundbreaking theory is being done by Dr. Edward Calabrese at University of Massachusetts, also an adjunct scholar to Cato’s Center for the Study of Science.

A leading industry group (the National Industrial Sand Association, NISA) makes a strong case that the existing OSHA standards are quite effective at greatly reducing, or even eliminating, occurrence of silicosis. So really, all OSHA needs to do is unify the existing regulations and better insure that they are enforced.

NISA has commissioned a scientific study of the dose-response behavior that is wider in scope and includes a greater and more detailed amount of epidemiological data than the existing studies relied upon by OSHA. From a NISA report:

While the association between silicosis and exposure to respirable crystalline silica is indisputable, there is still considerable uncertainty regarding the dose/response relationship of this association, particularly in the case of chronic simple silicosis, which is the most common form of silicosis.  It is unclear, for example, whether there is an effect threshold, or whether instead the dose/response curve is linear at even the lowest doses.  The slope of that curve is also uncertain.  As a result, there is uncertainty regarding the degree of risk remaining at various 8 hour time-weighted average exposures, including, most importantly, the current PEL of [0.10 mg/m3].  

In NISA’s view, this degree of uncertainty is unacceptable for a rulemaking of this magnitude.

The industry is being up-front about their commission (involving scientists at major universities involved in silica research) and has taken steps to be open and transparent about their involvement—or rather lack of involvement—in the study’s outcome. 

But, the results of the new study, instigated several years ago, are still forthcoming and consequently the industry has asked OSHA to wait until they are available (expected later this year) before issuing its final rule.

It’ll be interesting to see how this plays out, but preliminarily, this looks like another case of the government solving a problem that doesn’t really exist, in that existing regulations are sufficient to address the health concerns if they were better applied and enforced, and further, the promise of the new regulations is being greatly overplayed, saving many times more lives than our CDC says silicosis takes away.

But that’s the government at work—if some regulations are good, more must be better. Sadly, for the taxpayers and the regulated industries, it doesn’t always work out that way.