NCDENR - Division of Air Quality - Priorities for SAB review of toxic air pollutants



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Prioritization of Issues for Review by the Secretary's Scientific Advisory Board on Toxic Air Pollutants
Introduction This document provides an outline of criteria used by the Department of Environment and Natural Resources (DENR) in determining issues and air pollutant compounds to be brought before the Secretary's Scientific Advisory Board on Toxic Air Pollutants (SAB). The SAB was created to provide advice to DENR on topics related to toxicology and/or risk assessment. The charge to the SAB signed by the Secretary of DENR provides an outline for SAB duties, as does the "Report and Recommendations of the Air Toxics Panel of the North Carolina Academy of Sciences," final report dated September, 1986. Together, these documents help to provide guidance to the DEHNR Division of Air Quality in determining subject matter for consideration by the SAB. The agenda for the SAB is managed by the Toxics Protection Branch of the Division of Air Quality with approval from the Division Director, representing DENR. In this manner, DENR finalizes and assumes full responsibility for the compounds and issues on the SAB agenda. History In 1986, at the request of the North Carolina Division of Environmental Management, an Air Toxics Panel was created from within the North Carolina Academy of Sciences (NCAS). This panel was asked to determine a suitable approach for recommending acceptable ambient levels (AALs) for toxic air pollutants which carry the potential for exposures leading to adverse health effects as a result of industrial emissions in North Carolina. The panel outlined a variety of methods for performing this determination (see "Report and Recommendations...," above) and in January of 1987 recommended AALs for over 80 chemicals. The Air Toxics Panel also recommended that a "standing advisory committee on toxic air pollutants be appointed to deal with deferred, unresolved and recurrent issues related to the development or revision of AAL's for toxic air pollutants." This advisory committee was created in the form of the SAB on the 16th of May, 1990. The report written by the NCAS Air Toxics Panel provides some direction for items to be considered by the SAB. These include reviewing the original Panel's recommended AALs, determining the need for updated risk assessments and revised AALs, performing site-specific risk assessments and considering modifications in air guidelines where unique health risks from exposures to complex mixtures of chemicals might exist. The Panel report also contains a section entitled "Criteria for selecting chemicals for air guideline development" that, along with the Secretary's charge to the SAB (attachment 1), provides more specific information on issues to be considered by the SAB. Prioritization of issues to be considered by the Secretary's Scientific Advisory Board on Toxic Air Pollutants DENR's Division of Air Quality develops the agenda for the SAB. The following section outlines the current prioritization policy for pollutants which may be considered by the SAB. A figure is included (attachment 2) to provide a visual representation of the current prioritization scheme. The "Response Paradigm" Of principal importance are those issues that are related to ongoing health risks in the state of North Carolina. In general, these issues will take precedence over all other current and impending issues facing the SAB. This flexibility allows the Toxics Protection Branch and the SAB to remain as responsive as possible to ongoing public health issues. Response requests may include ambient air concentration recommendations for currently unregulated pollutants or revisitation of a current AAL. Actions of this sort may be initiated by specific directives from the Governor of North Carolina or the Secretary of DENR or they may be initiated following recommendation by the Division of Epidemiology. These types of situations are illustrated in attachment 2 as part of the "Response Paradigm." The prioritization scheme for these response-type situations is as follows: Issues specifically directed by the Governor of North Carolina or the Secretary of DENR. Highest priority is given to these requests, which are generally forwarded as written directives. It is not expected that this authority will be used frequently - however, these types of requests will take precedence over current and impending issues facing the SAB. Issues determined to be of immediate public health consequence by the Division of Epidemiology or the State Health Director. These cases are also not expected to arise frequently but will take precedence over current and impending issues facing the SAB. The "Prevention Paradigm" When issues of immediate public health concern are not facing the Toxics Protection Branch or the SAB, consideration will instead extend to toxic pollutants emitted to the air in North Carolina which carry the potential for adverse health consequences. In general, unregulated air pollutants will be the first considered for human health risk with criteria including emissions quantity and toxicological and chemical classification having a bearing on the order of consideration. On occasion, toxic air pollutants with established North Carolina AALs will also be reexamined in situations where new toxicological information warrants a reevaluation of the current AAL. Attachment 2 illustrates the policy that has been adopted for prioritizing compounds under the "Prevention Paradigm." What follows is a more thorough explanation: "HAPs not TAPs." The 1990 federal Clean Air Act Amendments contains a list of 189 substances designated by the United States Congress as Hazardous Air Pollutants (HAPs). Of the approximately 189 HAPs, roughly 87 are currently regulated in North Carolina as Toxic Air Pollutants (TAPs). In an effort to more clearly identify those "non-TAP HAPs" that may present a public health threat in North Carolina, the Toxics Protection Branch has deferred the following HAPs from consideration for review by the SAB: 1) those compounds emitted in quantities of less than 500 pounds per year in the latest emission inventory and 2) those compounds falling under the exclusive category of pesticide, herbicide, fungicide or rodenticide^. Review of the 1992 Toxics Release Inventory (TRI) indicates that a total of 54 HAPs remain eligible for SAB review. The Toxics Protection Branch of the Division of Air Quality prioritizes the remaining eligible compounds for SAB consideration. Important considerations include emissions quantity in North Carolina, toxicity, exposure potential, and availability of toxicological information. Further refinement is achieved by grouping compounds with similarities in chemical structure, class, mechanism of toxicity, etc. In addition, the HAPs emitted in North Carolina that are associated with a particular MACT source category may be given higher priority for SAB consideration so that the AAL is in place at the time MACT is implemented. Review of current AALs. The SAB and the Toxics Protection Branch will periodically review the current AALs to determine whether the existing guidelines are adequate for the protection of public health. In some cases, new toxicological information may be available which warrants reexamination of the Air Toxics Panel's original recommendation. Prioritization of these reviews incorporates many of the same considerations outlined above,including toxicity, emissions quantity and exposure potential. Higher priority will be given to those situations where especially significant changes in toxicological classification arise, such as reclassification of carcinogenic potential. Citizens or industry representatives may request review of current AALs on toxicological grounds^*. The DENR will set the priority for SAB consideration of the review requested based on the aforementioned criteria. Other potential considerations. Focusing on those HAPs with greatest potential for adverse impacts on human health or the environment will be critical for effective risk management. It will also aid in allowing the state program to mesh with the federal Maximum Achievable Control Technology (MACT) program, particularly when residual risks are considered under the federal program. However, the HAPs list should not be interpreted as an all-inclusive list of toxic air pollutants. For example, the federal Toxics Release Inventory reports emission quantities of potentially hazardous compounds which may not be on the federal HAPs list. The DENR may ask the SAB to recommend acceptable ambient concentrations for some of these types of "non-HAP" hazardous chemicals should the potential for exposures leading to adverse health effects exist in North Carolina. Although issues confronted under the response paradigm are not normally predictable, the Toxics Protection Branch and the SAB regularly discuss upcoming compounds for review under the prevention paradigm. Click on prioritized list for those compounds on the SAB review list under the Prevention paradigm.

Prioritization of Issues for Review by the Secretary's Scientific Advisory Board on Toxic Air Pollutants

Introduction
This document provides an outline of criteria used by the Department of Environment and Natural Resources (DENR) in determining issues and air pollutant compounds to be brought before the Secretary's Scientific Advisory Board on Toxic Air Pollutants (SAB). The SAB was created to provide advice to DENR on topics related to toxicology and/or risk assessment. The charge to the SAB signed by the Secretary of DENR provides an outline for SAB duties, as does the "Report and Recommendations of the Air Toxics Panel of the North Carolina Academy of Sciences," final report dated September, 1986. Together, these documents help to provide guidance to the DEHNR Division of Air Quality in determining subject matter for consideration by the SAB. The agenda for the SAB is managed by the Toxics Protection Branch of the Division of Air Quality with approval from the Division Director, representing DENR. In this manner, DENR finalizes and assumes full responsibility for the compounds and issues on the SAB agenda.

History
In 1986, at the request of the North Carolina Division of Environmental Management, an Air Toxics Panel was created from within the North Carolina Academy of Sciences (NCAS). This panel was asked to determine a suitable approach for recommending acceptable ambient levels (AALs) for toxic air pollutants which carry the potential for exposures leading to adverse health effects as a result of industrial emissions in North Carolina. The panel outlined a variety of methods for performing this determination (see "Report and Recommendations...," above) and in January of 1987 recommended AALs for over 80 chemicals. The Air Toxics Panel also recommended that a "standing advisory committee on toxic air pollutants be appointed to deal with deferred, unresolved and recurrent issues related to the development or revision of AAL's for toxic air pollutants." This advisory committee was created in the form of the SAB on the 16th of May, 1990.

The report written by the NCAS Air Toxics Panel provides some direction for items to be considered by the SAB. These include reviewing the original Panel's recommended AALs, determining the need for updated risk assessments and revised AALs, performing site-specific risk assessments and considering modifications in air guidelines where unique health risks from exposures to complex mixtures of chemicals might exist. The Panel report also contains a section entitled "Criteria for selecting chemicals for air guideline development" that, along with the Secretary's charge to the SAB (attachment 1), provides more specific information on issues to be considered by the SAB.

Prioritization of issues to be considered by the Secretary's Scientific Advisory Board on Toxic Air Pollutants
DENR's Division of Air Quality develops the agenda for the SAB. The following section outlines the current prioritization policy for pollutants which may be considered by the SAB. A figure is included (attachment 2) to provide a visual representation of the current prioritization scheme.

The "Response Paradigm"
Of principal importance are those issues that are related to ongoing health risks in the state of North Carolina. In general, these issues will take precedence over all other current and impending issues facing the SAB. This flexibility allows the Toxics Protection Branch and the SAB to remain as responsive as possible to ongoing public health issues. Response requests may include ambient air concentration recommendations for currently unregulated pollutants or revisitation of a current AAL. Actions of this sort may be initiated by specific directives from the Governor of North Carolina or the Secretary of DENR or they may be initiated following recommendation by the Division of Epidemiology. These types of situations are illustrated in attachment 2 as part of the "Response Paradigm." The prioritization scheme for these response-type situations is as follows:

Issues specifically directed by the Governor of North Carolina or the Secretary of DENR. Highest priority is given to these requests, which are generally forwarded as written directives. It is not expected that this authority will be used frequently - however, these types of requests will take precedence over current and impending issues facing the SAB.
Issues determined to be of immediate public health consequence by the Division of Epidemiology or the State Health Director. These cases are also not expected to arise frequently but will take precedence over current and impending issues facing the SAB.

The "Prevention Paradigm"
When issues of immediate public health concern are not facing the Toxics Protection Branch or the SAB, consideration will instead extend to toxic pollutants emitted to the air in North Carolina which carry the potential for adverse health consequences. In general, unregulated air pollutants will be the first considered for human health risk with criteria including emissions quantity and toxicological and chemical classification having a bearing on the order of consideration. On occasion, toxic air pollutants with established North Carolina AALs will also be reexamined in situations where new toxicological information warrants a reevaluation of the current AAL. Attachment 2 illustrates the policy that has been adopted for prioritizing compounds under the "Prevention Paradigm." What follows is a more thorough explanation:

"HAPs not TAPs." The 1990 federal Clean Air Act Amendments contains a list of 189 substances designated by the United States Congress as Hazardous Air Pollutants (HAPs). Of the approximately 189 HAPs, roughly 87 are currently regulated in North Carolina as Toxic Air Pollutants (TAPs). In an effort to more clearly identify those "non-TAP HAPs" that may present a public health threat in North Carolina, the Toxics Protection Branch has deferred the following HAPs from consideration for review by the SAB: 1) those compounds emitted in quantities of less than 500 pounds per year in the latest emission inventory and 2) those compounds falling under the exclusive category of pesticide, herbicide, fungicide or rodenticide^*.
Review of the 1992 Toxics Release Inventory (TRI) indicates that a total of 54 HAPs remain eligible for SAB review. The Toxics Protection Branch of the Division of Air Quality prioritizes the remaining eligible compounds for SAB consideration. Important considerations include emissions quantity in North Carolina, toxicity, exposure potential, and availability of toxicological information. Further refinement is achieved by grouping compounds with similarities in chemical structure, class, mechanism of toxicity, etc. In addition, the HAPs emitted in North Carolina that are associated with a particular MACT source category may be given higher priority for SAB consideration so that the AAL is in place at the time MACT is implemented.
Review of current AALs. The SAB and the Toxics Protection Branch will periodically review the current AALs to determine whether the existing guidelines are adequate for the protection of public health. In some cases, new toxicological information may be available which warrants reexamination of the Air Toxics Panel's original recommendation. Prioritization of these reviews incorporates many of the same considerations outlined above,including toxicity, emissions quantity and exposure potential. Higher priority will be given to those situations where especially significant changes in toxicological classification arise, such as reclassification of carcinogenic potential. Citizens or industry representatives may request review of current AALs on toxicological grounds^**. The DENR will set the priority for SAB consideration of the review requested based on the aforementioned criteria.
Other potential considerations. Focusing on those HAPs with greatest potential for adverse impacts on human health or the environment will be critical for effective risk management. It will also aid in allowing the state program to mesh with the federal Maximum Achievable Control Technology (MACT) program, particularly when residual risks are considered under the federal program. However, the HAPs list should not be interpreted as an all-inclusive list of toxic air pollutants. For example, the federal Toxics Release Inventory reports emission quantities of potentially hazardous compounds which may not be on the federal HAPs list. The DENR may ask the SAB to recommend acceptable ambient concentrations for some of these types of "non-HAP" hazardous chemicals should the potential for exposures leading to adverse health effects exist in North Carolina.

Although issues confronted under the response paradigm are not normally predictable, the Toxics Protection Branch and the SAB regularly discuss upcoming compounds for review under the prevention paradigm. Click on prioritized list for those compounds on the SAB review list under the Prevention paradigm.