Natural Resources Board to Hear Informational Report on Silica

The Wisconsin Natural Resources Board will meet at 8:30AM on December 14th at the DNR headquarters in Madison. The Board will consider several items related to Land Management, Recreation, and Fisheries/Wildlife, approve or disapprove a couple scope statements and the 2011-13 capital development budget, and hear informational reports on silica, the Oak Creek Bluff Collapse, and commercial fishing.

The hot topic of the meeting is expected to be the informational Silica Report Briefing because a group of citizens recently petitioned the DNR to list dust from sand mines, often silica, as a toxic pollutant and regulate it. The sand mined in western Wisconsin has become increasingly popular as an agent used in hydraulic fracturing for natural gas. Mining for frac sand creates small particles of crystalline silica dust, which has been known to cause silicosis and other illnesses.

A silica study was conducted to evaluate the sources and amounts of amorphous and crystalline silica emissions and alternative strategies for minimizing public health risks. The final report was published August 30, 2011 and describes what is currently known about sources, health effects, exposures, controls and the regulatory status of silica in Wisconsin and in other states and countries. The study does not recommend policy actions but does provide options to policy makers regarding potential alternative strategies for additional regulation.

Excerpted below are highlights taken from the Executive Summary of the DNR Silica Study.

• Sources of crystalline silica are ubiquitous and include paved and unpaved roads, wind blown soil and agricultural activities (e.g., tilling and harvesting).
• Industrial sources of crystalline silica include construction, foundries, glass manufacturing, abrasive blasting or any industrial or commercial use of sand and quartz, and mining and rock crushing operations.
• Crystalline forms of silica (such as quartz) meet the definition of a known carcinogenic hazardous air pollutant (HAP)1 as defined in Wisconsin’s Air Toxics Rule, Ch. NR 445, Wis. Adm. Code. Wisconsin statutes have specific criteria which must be met in order for a hazardous air pollutant standard to be established.
• Amorphous forms of silica do not currently meet the decision rules for defining amorphous silica as a HAP because they have been delisted by the American Conference of Governmental Industrial Hygienists (ACGIH).
  No federal air quality standards for silica currently exist. Federal standards for particulate matter (PM), a component of which is silica, are in effect for PM 10 and PM2.5.
• The size of crystalline silica particles of most concern are those that are smaller than four microns (millionths of a meter), also called particulate matter 4 (PM4). There are no generally accepted methods for monitoring PM4 in ambient air.
• Controls for crystalline silica are the same controls typically used for particulate matter (PM). The extent of reduction from existing particulate matter (PM) controls is not currently known and will vary from source to source. The types and costs for these controls need to be evaluated on a facility-by-facility basis.
• Studies generally do not indicate the existence of any wide-spread significant concern about airborne crystalline silica exposures to individuals not living near an identified source of crystalline silica emissions. In circumstances where people live near a source of crystalline silica, data from other air pollution control agencies shows that silica ambient air concentrations could be above a level of concern. However, the data also suggests that other non-industrial sources contribute to the ambient levels.
• Of the states surveyed, six (Texas, California, Vermont, New York, New Jersey and Michigan) address emissions of crystalline silica. However, these states have not shown impacts from these sources on health. Some states use what may be considered a technology-based approach, focusing on control measures or specific management practices, while others establish an acceptable ambient air concentration of crystalline silica.
• Wisconsin Department of Natural Resources (WDNR) has extensive experience applying PM controls to many types of air pollution sources. For example, many permits for industrial sources require dust management plans and other controls to reduce PM emissions, which also help minimize crystalline silica emissions.
• Currently, WDNR has no crystalline silica monitoring data. Additional financial and staff resources would be needed to conduct crystalline silica monitoring. Monitoring to specifically analyze for crystalline silica is difficult, there are no federal standards and there is no standard reference method for monitoring crystalline silica in ambient air.
• The draft report was released to the public on January 4, 2011 and the WDNR received comments. Comments received requested additional WDNR actions including listing crystalline silica as a HAP, establishing acceptable ambient air concentrations and controls on sources and monitoring for crystalline silica. Other comments state that the WDNR does not have the authority to regulate silica, that only occupational exposures have been associated with silicosis and cancer risk and no public health risk exists from the lower level of exposure in ambient air.
   

The Executive Summary concludes: “A recurring theme from the literature review and survey is that very little conclusive information exists regarding sources, controls or levels of silica present in ambient air. This lack of data means it is not currently possible to determine conclusively whether or to what extent the quantity, duration or types of silica emissions in the state may be a public health concern. It would take significant additional efforts to fill in these data gaps. That said, Wisconsin has regulated PM for 40 years. The controls for PM are the same controls for crystalline silica. This means that for those crystalline silica sources where PM is controlled, crystalline silica emissions are also reduced.”

This post was authored by GLLF staff attorney Emily Kelchen.