Plastics News incorrectly implies in its April 15 article, “New federal silica exposure rule could cost billions” (April 18, Page 3) that “synthetic amorphous silica” (SAS) — including precipitated and fumed silicas as listed in paragraph five of the above referenced article — is subject to OSHA's March 25 final rule on respirable crystalline silica.
While OSHA has determined that employees exposed to respirable crystalline silica at the previous permissible exposure limits face a significant risk of material impairment to their health, only the respirable fraction of crystalline silica is covered by the new rule. OSHA does not include amorphous silica in either its proposed or final rule.
Workers and consumers, as well as your readers, must be made aware of the significant and fundamental differences in health effects between “crystalline silica” (especially “respirable crystalline silica”) and “synthetic amorphous silica” (SAS). This distinction is important because many industrial and consumer products may list the generic term “silica” as a component when, in fact, they contain SAS. SAS does not pose the health effect risks associated with “crystalline silica.”
The health effects of SAS have been reviewed in recent years, and the available data on worker populations and animal studies support the conclusion that these substances are non-toxic.
Synthetic Amorphous Silica
and Silicate Industry Association
South Russell, Ohio