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Published: May, 2011; Vol 7, Num 12

 

Silica:Clearing the Air

By Scott Schneider

After setbacks on previously announced noise and MSD initiatives, OSHA is expected to kick off another regulatory initiative this month: the long-sought Silica Standard.

An Old Problem

Construction work is often dusty, and workers breathe in dust when they cut or drill into concrete or rock. The dust can get deep into the lungs and cause damage.

Many construction tasks expose workers to silica-laden dust.

This is not news.  Over 300 years ago, in the first book ever published on occupational diseases, Bernardino Ramazzini wrote about it, identifying respiratory disease among stonecutters. Two hundred years later, Alice Hamilton, the founder of modern occupational health, identified lung disease from silica exposures among granite workers in Vermont.

Tunnel workers were the next associated with the disorder. In the late 1930s, the Gauley Bridge Tunnel was dug in West Virginia. Dust was high with highly concentrated levels of silica, and over 400 workers died from acute silicosis (video). Congress and then-President Franklin Roosevelt were determined to do something about it. Roosevelt named a social reformer, Frances Perkins, as the first Secretary of Labor and the first woman ever named to a cabinet post. When she took the job in the 1938, she focused on the silicosis problem. She started the “Stop Silicosis" (video) campaign and held a National Silicosis Conference. Yet, absent federal regulation, the problem continued.

In 1971, soon after its establishment, OSHA adopted a list of chemical threshold limit values (TLVs) that the American Conference of Government Industrial Hygienists (ACGIH) had developed over the years.  Among these retitled permissible exposure limits (PELs) was one for silica. Just three years later, the new National Institute for Occupational Safety and Health (NIOSH) recommended that the limit be significantly reduced (to 0.05 mg/m), but OSHA took no action. In 1996, Secretary of Labor Robert Reich tried again. Working with NIOSH, he initiated a campaign to get workers to recognize that “It’s Not Just Dust” and held another national conference.  Still, industry opposition kept OSHA from proposing a lowered PEL. As evidence of extensive exposure and risk continued to mount, ACGIH (in 2006) reduced its TLV to 0.025 mg/m.

Today, despite 40 years of scientific advance and many recommendations by health professionals, OSHA’s PEL for silica remains unchanged. Now, however, the agency finally seems poised to act.

The Dangers

National statistics officially show that about 150 workers die each year from silicosis, a dust disease caused when the lungs form scar tissue around deeply lodged silica particles, making it harder for the body to get oxygen. But this number is just the tip of the iceberg. Most doctors do not know about silicosis and never think to ask their patients about on-the-job silica exposures. As a result, death from silicosis is often thought to be from other respiratory illnesses such as pneumonia. In a recent New Jersey study of construction workers who died from lung diseases, x-rays showed that 8.5 percent (one out of 12) had silicosis that was never diagnosed. Other studies also confirm that the incidence of silicosis is significantly underreported.

Almost 30 years ago, we also learned that silica causes lung cancer. Experts believe even more silica-exposed workers die from lung cancer than from silicosis. Other lung diseases, like chronic obstructive pulmonary disease (COPD), can also be caused by silica dust.

Dust can be contained with wet or vacuum controls.

Clearing the Air

Sadly,these deaths and illnesses could be easily prevented. Many studies show that simply using water to hold down dust or a local exhaust system to suck it up effectively reduces dust levels by over 90 percent.  Many tools are now available with built-in exhausts or water sprays or accessories that do the job. These simple controls are inexpensive, easy to use and widely available.  Other tools can be readily retrofitted with a water spray or exhaust hood.

In recent years, some states have taken action on their own. New Jersey banned the dry cutting of concrete in 2004. California followed suit a few years later. Neither state has had compliance problems. Contractors followed the rules, and exposures were significantly reduced.

The OSHA Proposal

 

OSHA will be proposing a comprehensive health standard to prevent diseases from silica exposures. Of course, lowering the PEL to reflect current knowledge about the risks of exposure will be part of the standard. More importantly, OSHA indicates that it will propose a simple, practical assessment scheme that small employers can use to easily comply with the standard’s provisions. In the past, compliance with the PEL required expensive regular monitoring of silica concentrations. In construction, however, where exposure levels can change day to day as the site and work evolve in the course of the project, exposure levels measured one day tell nothing about exposures the next. A simpler and less expensive approach is to identify effective controls for high-risk tasks and require their use when those tasks are performed. Why require constant monitoring when it is known that a certain task produces high exposure? Why not just require that exposures from that task be controlled? Judging from the draft standard, this appears to be the approach that OSHA will adopt.

It’s About Time!

After years of study and decades of discussion, OSHA now appears ready to do something about the silica problem.  The pledges made by Frances Perkins over 70 years ago may now come true. We can “stop silicosis,” silica-related lung cancer and other lung diseases as well.It’s about time.

[Scott Schneider is the LHSFNA’s Occupational Safety and Health Division Director.]

The LHSFNA website has a recently-added set of Silica Resource Links. In addition, the Fund publishes two silica-related pamphlets – Controlling Silica Exposures in Construction and What Physicians Need to Know about Silicosis in Construction, Demolition and Renovation Workers – and a manual to guide establishment of a Model Silica Protection Program for Contractors. A health alert for workers, Silicosis (in English and Spanish), is also available through the Fund’s online Publications Catalogue.