Know the Dangers of Crystalline Silica Exposure

OSHA issued a proposed rule for a substance-specific standard on crystalline silica in September 2013, and for good reason. Respirable crystalline silica, which is 100 times smaller than an ordinary grain of sand, is associated with cutting, sawing, grinding, mixing, drilling and crushing stone, rock, concrete, brick, block, mortar and certain industrial sands. Exposure to crystalline silica is associated with a number of negative health effects, the most prominent being silicosis.

Silicosis is a progressive and incurable disease in which the accumulation of respirable crystalline silica particles causes an inflammatory reaction in the lungs, leading to lung damage, shortness of breath and reduced pulmonary function. In some cases, the disease can result in permanent disability or even death. Unhealthful exposures may go unnoticed for months or even years due to the slow onset of symptoms.

The proposed rule would update crystalline silica’s permissible exposure limit for the first time since 1971, cutting the current limit for general industry by 50 percent and the limit for construction and shipyards by 80 percent.

The proposal also requires a number of administrative measures, air monitoring, medical examinations and engineering controls to reduce worker exposure to the deadly dust. Few question the fact that breathing crystalline silica can be harmful to health. However, some believe the cost of controlling for the substance is simply too high.

Cost of Controls vs. Exposure

The Construction Industry Safety Coalition sent a letter to OSHA on March 15, alleging that OSHA’s studies grossly underestimate compliance costs associated with worker protections. The letter, received two years after the end of OSHA’s commenting period, demonstrates the coalition’s continued concern about the proposed rule.

Employers need health and safety rules that are reasonable and can be followed without undue hardship. At the same time, employers and workers alike need health and safety rules that provide an appropriate level of protection. The coalition may have made some good points about the high cost of silica controls, but the consequences of exposure could be even higher. Workers and employers will both bear the consequences of crystalline silica exposure if it is not appropriately tempered.

Set the Rules

Exposure concentrations considered “safe and healthful” are debatable, and hearty debate is generally good for rule making. However, debates also tend to slow the rule-making process. Several factors complicate decisions about exposure levels.

Myth of singular exposures: Most exposure levels are set based on the projected health effects a worker might expect from exposure to a single chemical over an eight-hour shift. Singular exposures are exceptionally rare. Most commercial products are made from a mixture of chemicals, and most workplaces have many product mixtures simultaneously present in the work environment. Chemical exposures do not stop when workers leave the workplace. Depending on the number, concentration and types of chemicals involved, the effects of simultaneous, combined exposures may be significantly different from exposure to chemicals independently.

Myth of an average worker: Average people exist in statistics; individual susceptibility varies widely in the real world. Age, genetic predisposition, pre-existing health conditions and other factors determine how much of a contaminant individual workers can tolerate without adverse effects. Because of the wide variation in individual susceptibility, a percentage of exposed workers may experience discomfort from some substances at concentrations well below established limits. To account for these differences, exposure levels are commonly set at a level where most employees will not suffer adverse effects. Godspeed and best wishes to you if you don’t happen to belong to the”most employees” class of workers, though.

Myth of average exposure conditions: Working conditions also have a bearing on the severity of exposures. If an individual is under a heavy workload and is breathing rapidly, the person will inhale more of a contaminant than a similar individual under a lighter workload. Based on respiration alone, it is possible for employees to receive a variety of different exposures over the same time period at the same ambient concentration.

Protect Against the Unknown

Hazardous chemicals will not be appropriately regulated until causative correlations can be established. In other words, what we don’t know can hurt us. Noxious odors or immediate pain and irritation after exposures alert workers to problems. Many chemicals, including crystalline silica, don’t have pronounced warning properties. The absence of warning properties means workers may receive unmitigated exposures over an extended period before health effects are realized and addressed accordingly.

Additionally, it may be difficult to identify the connection between health effects and chemical exposures when there is a lengthy delay between exposures and health effects. Under-protective exposure limits will be the status quo until enough workers have gotten sick and understand they became sick because of these workplace exposures. Workers should be advised not to rely on health effects as the only indicator of what is safe and avoid unnecessary exposure—even when chemicals are considered to be set at a safe level.

Play It Safe

When setting exposure controls, it is wise to err on the side of safety. Well-considered threshold values are, at best, approximations of levels at which health effects are likely to occur. Individual susceptibility, combined effects of exposures and other factors may leave some workers unprotected.

OSHA exposure limits lag health and safety standards set by other organizations like the American Conference of Governmental Industrial Hygienists and the National Institute for Occupational Safety and Health.

Since regulations are commonly dated—as is the case with crystalline silica—simply adhering to current regulatory limits (i.e. exposing workers as much as the law allows) is ill advised.

Leading companies follow the most protective standards and begin implementing controls well before these levels are reached.

While the approximate nature of threshold values doesn’t make an absolute case for tighter controls, it does suggest that a conservative approach should be carefully considered. A balance must be achieved. The answer to the debate about occupational exposure limits, and safety rules in general, lies somewhere between workplace health, safety and the environmental decrees of “technologically feasible” and “reasonably achievable.”

Because we will always have more information tomorrow than we know today, many workplace health and safety professionals believe that exposures should always be kept “as low as reasonably achievable (ALARA),” which is a good recommendation for respirable crystalline silica, anyway.