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Nearly five years after OSHA’s permissible exposure limits (PEL) for beryllium were updated, slag continues to be used in industrial coatings sites across the nation. But a growing body of research that is increasing public awareness about safe abrasive alternatives has begun to turn the tide.

Mid 2021, OSHA released a new set of beryllium resources that expanded upon its 2017 beryllium limits and brought slag’s risks back into the limelight. The expansion and update of these resources softened the stand on beryllium in slag abrasives and generalized that beryllium is, in fact, in all abrasives in trace amounts, which is certainly true. This doesn’t change the fact that trace amounts of heavy metals present can pose a real threat to the health and safety of workers—hence, the reason why there is a Beryllium Rule. Each blast abrasive is different in how it performs and in what trace heavy metals are released into the air on blasting. 

Slag abrasives also made headlines again last October, this time for their environmental hazards, when a judge refused to dismiss a CERCLA lawsuit alleging Citigroup mishandled slag at a site near the Mississippi River. Now, as the fifth anniversary of OSHA’s Beryllium Rule draws near, new research is shedding light on the true dynamics of slag blasting—and the safer alternative that garnet provides.

New Research on Slag and Other Non-Natural Abrasives

OSHA famously studied beryllium’s carcinogenic effects for 30 years before issuing its 2017 limits. By now, many coatings industry professionals know the rule inside and out: up to 0.2 μg/m3 (with the actionable limit: 0.1 μg/m3) over eight hours, or a short-term exposure limit of 2.0 μg/m3 over 15 minutes. The heavy metal’s health implications are also well-documented. Designated as a Class 1 carcinogen by the International Agency for Research on Cancer (IARC), beryllium has been linked to both lung cancer and chronic beryllium disease (CBD). One of OSHA’s latest resources is devoted to the beryllium lymphocyte proliferation test, BeLPT for short, which helps workers determine if their immune system is sensitized to beryllium—a precursor to CBD.

Beryllium’s limits and health risks are clear. But what’s often less clear is just how much beryllium enters the air during an abrasive blasting job. Between dust and disposal, even the most experienced safety managers and hygienists can struggle to gauge the full risk of slag simply by what’s coming out of the bag. In new research, GMA Garnet tackled this quagmire head on by measuring the precise beryllium levels in a variety of industrial slags. In some tests, some slag abrasives produced six times more beryllium than permitted by OSHA.

In other more recent testing on non-slag abrasives advertised as “engineered alloy of oxide minerals,” the actual levels of beryllium by weight recorded highlighted that, on average, 7.3 mg/kg was detected in these products. Though this seems miniscule, compare that with the highest coal slag beryllium by weight: 1.9 mg/kg. Then compare these with garnet products, which are recorded to have, on average, 0.02 mg/kg of beryllium by weight. There is a big difference in potential hazard.

Considering that the worst-performing coal slag product was six times over the OSHA permitted threshold levels in their air sample results, what result would the “engineered alloy of oxide minerals” air sample produce? Though these tests have not been performed, there is considerable uncertainty surrounding all these non-natural abrasives and the potential health risks that could be faced for onsite workers in close proximity to blasting operations. Businesses could also face potential environmental problems.

These findings make the stakes of blasting with slags and other non-natural materials all that much higher—and safer alternatives all the more necessary. Although every blasting abrasive poses some level of risk, it is highly unlikely that garnet—which has only minute traces of heavy metals interlocked in the molecular structure of the material—would cause air or environmental contamination. With its inherent hardness and toughness, garnet produces less dust than slags, which helps to increase productivity and efficiency of the blasting process. Combined, these characteristics give garnet a more desirable safety profile.

Independent Tests Are Clearing the Air

According to industry research, slags and other non-slag abrasives can contain traces of beryllium up to 0.1% by weight. But because slags, in particular, shatter on impact during blasting, that number doesn’t tell the full story. The amount of beryllium released into the air can greatly exceed the highest legal levels permitted by OSHA. Recent independent tests conducted by a third-party HSE consultant using industry standard analytical methodologies, including NIOSH 7300M, 7303M, 0600, and OSHA 142 V4, zeroed in on air sample test levels, finding that the dustiest slag abrasives contained beryllium levels of up to five times higher than the OSHA threshold.

In its PPE requirements for various hazardous materials, the National Institute for Occupational Safety and Health (NIOSH) advises workers to wear full self-contained breathing equipment when beryllium levels reach 0.01 mg/m3 or higher. This PPE goes well beyond a mere blast hood, posing significant cost and productivity challenges for industrial teams still clinging to slag.

Rising Awareness of Environmental Hazards

Slags, in particular, require notoriously high consumption to get the job done—sometimes two to five times higher consumption compared with a good quality garnet abrasive. This exposes maintenance teams to more dust, more disposal work and more risk of Environmental Protection Agency (EPA) violations. Slags and non-natural abrasives are not inert, and there may be higher potential for heavy metal leaching over and above other inert abrasives, such as a mineral garnet.

Safety managers often craft solutions that fall within EPA guidelines for the disposal of slag. But as the public becomes more aware of slag’s health concerns—this small town in Iowa is just one in a growing trend—safety workarounds are Band-Aids at best. Slags often contain arsenic, cadmium, chromium, lead, manganese and other toxic heavy metals. If slag isn’t properly managed and contained, it can quickly contaminate bodies of water such as the Mississippi River, the environmental focus of the Citigroup slag lawsuit.

Years after the 2017 OSHA beryllium limits were released, slag continues to pose hazards to the health and safety of workers, communities and the environment. But as research exposes the true risk of slag blasting, safety managers have more alternatives than ever—including garnet, which falls well under OSHA’s beryllium limit in independent testing and has extremely low levels of the toxic heavy metals found in slag.