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## Schools Air Toxics Monitoring Activity (2009)

Uses of Health Effects Informatio n in Evaluating Sample Results

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1. Introduction

EPA has developed an initiative to impleme nt Administrator Jack son’s commitment to assess potentially elevated ambi ent (outdoor) concentrations of air toxics at some of our nation’s schools (generally described at www.epa.gov/schoolair ). This monitoring activity is described in the project monitoring plan and qua lity assurance project plan (available on the schools web site: http://www.epa.gov/schoolair/t echinfo.html). This monitoring is targeting key hazardous air pollutants (HAPs or air toxics ) at each site (i.e., those identified by either the Risk-Screening Environmental Indicators (RSEI) Model or the National Air Toxics Assessments (NATA) national-scale assessment as the local risk driver s, or by information provided by EPA, Regions and States). Ke y pollutants differ among the monitored schools based on what this background information i ndicated regarding pollutant emissions, and potential air concentrations and risk in each ar ea. The monitoring data and other information collected for each school during this initiative will allow us to assess levels of the key pollutants a occurring at these sites including the potential for contributions from nearby

sources.

The ambient air monitoring data collected at each site (along with other site- or sourcespecific information as well as information on typi cal regional or national levels) will be used to facilitate decisions regard ing priority for and type of any follow-up actions near each school. In considering the pollutants monitore d at each site and poten tial follow-up actions, EPA recognizes that data from ongoing m onitoring programs (e.g., monitoring at the National Air Toxics Trends Sites or NATTS) in dicate that levels of some pollutants are commonly higher in urban areas than elsewhere. While in some locations these pollutants (e.g., benzene and acrolein) may be associated with specific industrial fac ilities, they are also

associated with mobile source emissions and are commonly occurring at sites near urban areas or near large roadways a nd other transporta tion facilities ( http://www.epa.gov/otaq/toxics.htm ). Accordingly, EPA has taken several actions to reduce

mobile source emissions nati onally and maintains severa l ongoing programs aimed at achieving reductions in ambient air concentrations of these hazardous air pollutants from mobile sources ( http://www.epa.gov/otaq/toxics.htm#epamsat ). In addition to these national steps that are expected to reduce concentratio ns on a local basis as they are implemented, there are steps that individuals and communitie s can take to achieve additional reductions ( http://www.epa.gov/otaq/consumer.htm ).

a At each site, monitoring has been targeted to get information on the key HAPs about which the background information indicated a potential for concern. In anal yzing air samples for these key pollutants, samples are also being analyzed for some additional pollutants that ar e routinely included in the analytical methods for the key pollutants. While analysis of the dataset collected for each school will focus attention on the key HAPs,

results for other HAPs monitored at the school will also be reviewed consistent with the approach described in

this document.09/10/09

2 of 24 EPA/OAQPS will evaluate the full dataset for th e key pollutants at each school, in light of information particular to the sc hool and its location, in order to identify th e school’s priority for follow-up activities. That evaluation will in clude consideration of several analyses and factors. These will generally include the site -specific ambient air measurements along with other site and source-specific information, as well as, info rmation on typical national and regional levels and long-term health risk-rel ated exposure concentrations for monitored pollutants. Prior to the avai lability of a full dataset for each location, EPA will be making available on the public web site ( www.epa.gov/schoolair ) an interim presentation, including individual sample measurements for key polluta nts. As part of this interim presentation, EPA also intends to provide, as described in section 3 below, conservatively developed

health risk-related individual sa mple screening levels for all key pollutants. In instances where individual sample concentrations occur above these sample screening levels, the pollutant-specific health effects informati on will be evaluated along with information concerning the sample collection and potenti al sources of the monitored pollutant. b
Additionally, for some nationally key pollutants, such as t hose associated with mobile sources, EPA may provide information on nationally common concentrations for reference. This document, prepared for reference by th e EPA schools air toxics team, describes the

various uses of health effects information in evaluating sample results, usi ng screening or comparison levels and in further investigati on of results higher than such screening or comparison levels.

2. Uses of Health Effects Information

There are several uses of health effects information for the pollutants monitored in this project. As sample results are rece ived from the analytical laboratory c , EPA will be reviewing the data to identify a ny situations where additional a ttention may be appropriate to confirm sample results and to assess the pot ential for immediate health concerns. To facilitate the identification of sample results to receive such additio nal attention, we have developed individual sample screening levels (describ ed below in section 3). d Any sample results higher than these sample screening le vels will be further considered in light of chemical-specific information on health e ffects (section 4), along with information concerning the sample collection and potential s ources of the monitored pollutant. Lastly, the multi-faceted analysis of th e full monitoring dataset at a site, which will not entail a detailed risk assessment, will include consideration of projected estimates for the long-term average concentration of the monitored air toxics in light of health-based comparison levels. Accordingly, long-term comparison levels have been developed for use in the full dataset analysis (described below in section 5).

b While our main focus is on the key pollutants at each school (i.e., those pollutants fo r which background information indicated emissions and potential concentra tions that supported the monitoring activity), we are screening sample results for other pollutants monitored using individual sample screening levels and approach

described in sections 3 and 4 below.

c A quality assurance and quality contro l program is a component of the monito ring program that is followed by the sample collection team and analytical laboratory in producing sample results.

d At this step we are also reviewing national levels of some air toxics in recognition of their common occurrence at levels of risk-related interest nationally or in some regions. These typical ambient levels are not the focus of nor are they otherwise discussed in this document.09/10/09

3 of 24 3. Development of Individual Sample Screening Levels

This section describes the appr oach employed for developing sc reening-level values for use in reviewing individual sample measurements . Prior to developi ng or identifying these screening levels, priority was given to recognition of relevant and appropriate air standards or regulations, such as in the case of the r ecently updated National Ambient Air Quality Standards (NAAQS) for lead. For the remaini ng chemicals, health risk-related sample screening levels were calculated using EPA risk assessment guidance and precedents. The objective in developing individual sample screening levels for these air toxics is to identify

air concentrations to which c ontinuous exposures over a few days would be unlikely to be associated with appreciable risk of adverse heal th effects. These values are intended to help EPA to identify contaminants for which closer attention may be appropriate to confirm sample results and to assess the potential for any immediate health concerns. These sample screening values are considered reasonably conservative for th e presumed exposure scenario at hand, such that individual resu lts above these concentrations should not be presumed to be cause for alarm. These sample screening levels are not intended to de fine clean up or action

levels.

As the ambient air samples are collected ove r a 24-hour period, the e xposure duration of interest in developing individual sample screening levels is on the order of a few days (shortterm). As described below, established refe rence concentrations, dose-response assessments or other similar benchmarks for a time period of this length are not available for all of the monitored pollutants. In identifying surrogate exposure levels for use in lieu of short-term values, we have chosen to consider longer-term (intermediate) screening levels for which the exposure duration extends from weeks to a year. These intermediate screening levels have been developed consistent with the use of such levels in th e 2005-06 monitoring conducted in

association with activities in re sponse to hurricane Katrina in the Louisiana, Mississippi, and

Alabama. e

In summary, the individual sample screening le vels presented here represent short-term (or intermediate) duration inhalation exposure estimat es that are unlikely to be associated with appreciable risk of adverse health effects for continuously exposed populations (including sensitive subgroups). These levels are not design ed to predict the occurrence of effects, and individual sample measurements greater than the screening levels do not imply an immediate health threat. Rather, findings of individua l sample measurements above these screening

levels will receive additional at tention to confirm sample results and to assess the potential for any immediate health concerns (a s described in section 4 below).

At each site, monitoring has been targeted to get information on a limited set of key hazardous air pollutants (HAPs or air toxics) f . These pollutants are the primary focus of our

e Intermediate duration values were selected in the Katrina recovery monitoring activity with the presumption that a one-year exposure duration would conservatively and reasonably account for the potential of burning and/or demolition activities to go on longer than the presumed initial 3-month estimate for such activities.

f Section 112(b) of the Clean Air Act identifies 189 hazard ous air pollutants, three of which have subsequently been removed from this list. These pollutants, commonly called “air toxics” are the focus of regulatory actions involving stationary sources described by CAA section 112 and are distinguished from the six pollutants for09/10/09

4 of 24 monitoring activities at a site and a priority for us based on our emissions, modeling and other information. Accordingly, the sample screening levels for the full set of these key pollutants are presented in the first table at the en d of this section (Table 1). In analyzing air samples for these key pollutants, we will also be analyzing samples for some other pollutants (both HAPs and others) that can be economica lly measured at the same time. Sample screening levels for these addi tional HAPs are presented in Appe ndix A. Similar information for pollutants that are not HAPs is described in Appendix B.

Individual sample screening levels were set for the monitored HAPs, using the following prioritized approach. g

1. In considering a sample screening level fo r lead, preference was given to use of the National Ambient Air Quality Standards. A review of the NAAQS for lead was completed in October 2008. The revised primary standard h reflects the health effects evidence available in that review and pr ovides increased protection for children and other at-risk populations agains t an array of adverse health effects, most notably including neurological effects in children, including neurocognitive and

neurobehavioral eff ects (73 FR 66964).

2. For pollutants for which ATSDR has devel oped acute Minimal Risk Levels (MRLs), the individual sample screening levels were set to these MRLs. ATSDR defines each MRL as “an estimate of the daily human exposure to a hazardous substance that is likely to be without appreci able risk of adverse non cancer health effects over a specified duration of exposure” ( http://www.atsdr.cdc.gov/mrls/ ). Acute MRLs are considered appropriately pr otective comparison levels fo r screening of individual samples in this project because they were developed to be protective of short-term continuous exposures lasting up to 14 days (24 hours each day).

3. In looking for surrogates for chemicals for which no ATSDR acute MRL or similar duration value was available, we looked to longer- vs shorter-term duration exposure levels in keeping with the description that the sample screening levels be reasonably conservative for the presumed exposure scen ario and that the exposure duration of interest is on the order of a few days. i Thus, for the remaining pollutants for which

ATSDR has not established acute MRLs a nd for which longer-term risk-related exposure concentrations were available, su rrogates for short-term screening levels were developed from longer-term risk-relate d exposure concentrations. The approach for these surrogates focuses on what are te rmed “intermediate” duration exposures, which range up to one year duration. Thus, when used in lieu of short-term values

which criteria and national ambient air quality standards (NAAQS) are developed as described in section 108. One of the criteria pollutants, lead, is also re presented, as lead compounds, on the HAP list.

g Although this project targets HAPs, the analytical methods employed include several non-HAPs, such that data are being generated for those pollutants as well. Although the air toxics to which EPA assigns greatest concern nationally are the HAPs, a health risk-related screening was also applied to the individual sample results for the non-HAPs. The screening levels employed for this purpose are identified in Appendix A.

h The NAAQS for lead is 0.15 μg/m 3 in total suspended particles, applied as an average over a 3-month period.

i Other short-term duration exposure levels presented in OAQPS Table 2 include the California Environmental Protection Agency’s acute reference exposure levels, the exposure durations for which are 24 hours for most pollutants and somewhat shorter than that for a few.09/10/09

5 of 24 these values for most pollutant s are considered to inheren tly have an extra level of

conservatism than would short-term va lues had they been available.

The approach for deriving intermediate scr eening levels described here is that which EPA relied upon in the Hurricane Katrin a ambient air monitoring activity. Preliminary screening values were first identified separately for (a) effects for which

reference concentrations have been devel oped (usually considered to have nonlinear or “threshold” exposure-response relationships ) and, (b) if pertinen t to the pollutant, linear cancer risk (built upon EPA’s default carcinogen assumption, which is accepted

in lieu of a conclusion to th e contrary, of some cancer risk associated with any level of exposure). The final intermediate screen ing level is the lower of the subsequent two values (described in s ections (a) a nd (b) below).

a. To develop a preliminary screening le vel for “threshold” effects for these pollutants, the ATSDR intermediate inhalation minimal risk level was used (MRL inter ; see http://www.atsdr.cdc.gov/mrls.html ). Values for the MRL inter are developed to be protective of exposu res ranging from two weeks to a year.

When the MRL inter was not available for a comp ound, a value of ten times the

chronic Reference Concentration (RfC) or other similar value j was used

instead as an estimate of the intermed iate (subchronic) comparison value. Specifically, the preliminary screening le vel (SL) for a threshold chemical (in

the absence of a MRL inter ) is:

SL threshold = (10)(RfC) The application of a factor of 10 k is commonly used by the Superfund program for making decisions regardi ng emergency removal actions using a time frame with an upper bound of appr oximately a year (USEPA, 1997) to

account for the fact that chronic toxic ity values (e.g., RfCs) are being applied to the less than chronic (sub-chronic) time periods of expected exposure.

b. For linear carcinogenic compounds, the linear cancer risk-based screening

levels were set at concentrati ons for which the upper-bound lifetime probability of developing cancer would be one hundred-in-a-million (1x10 -4 ), if exposure occurred continuously at the concentration for one year. l The one-

j After EPA IRIS chronic RfCs (referred to as “chronic Rf Cs” in Tables 1-3 in this document), the next source consulted was ATSDR chronic MRLs, then California EPA chronic Reference Exposure Levels, and lastly HEAST chronic RfCs. This hierarchy fo r identification of chronic reference concentrations is consistent with that used in Table 1 of OAQPS toxicity values available on the EPA web site ( http://www.epa.gov/ttn/atw/toxsource/summary.html ). Information from that table was updated as needed.

k In recognition of the uncertainty of this approach for developing an intermediate duration screening level from a value derived for chronic exposures, we have deviated from this in some instances . For example, where the

chronic RfC was set with human data and with a cumula tive uncertainty factor equal to or less than 10), the factor of 10 was not applied and the chronic RfC was us ed as is. This was the case for cobalt, beryllium and

selenium.

l The cancer risk level used here (1x10 -4 ) reflects the upper bound of the Ag ency’s traditional acceptable risk range (10 -4 to 10 -6 ), which plays a role in both the hazardous air pollutant and Superfund programs. For example, in the 1989 setting of the “benzene NESH AP”, which has a precedent-setting role in the HAP program, EPA stated that an additional cancer risk (assoc iated with air toxics emitted from a stationary source)09/10/09

6 of 24 year exposure duration is c onsistent with the time fr ame of the intermediate MRLs. Specifically, the preliminary linea r cancer risk-based screening levels

were calculated as:

SL

cancer = (1E-04/IUR)(70)

where the IUR is the inhalation unit ri sk factor (or slope), expressed as ( μ g/m 3 ) -1 . The IURs used in this exer cise are those in the EPA OAQPS Toxicity Table 1 (http://www.epa .gov/ttn/atw/toxsource/summary.html ). m

Table 1. Individual Sample Screening Leve ls for Key (aka “driver”) HAP Analytes.

Analyte Individual Sample Screening Level 1 Value from which Screening Level

Derived

Metals 2 ng/m 3
Arsenic (PM 10 focus) 150 (I)3 chronic REL

Chromium-hexavalent 580 (I) IUR Cobalt (PM 10 focus) 100 (I) chronic MRL

Lead 4 -TSP The lead NAAQS is a rolling 3-month average of

150 (I) ng/m3 lead in TSP. Manganese (PM 10 focus) 500 (I) chronic RfC Nickel (PM 10 focus) 200 (I) inter. MRL VOCs/Carbonyls μ g/m 3
Acetaldehyde 90 (I) chronic RfC Acrolein 7 acute MRL (0.003 ppm)

Benzene 30 acute MRL (0.009 ppm)
1,3-Butadiene 20 (I) chronic RfC 4,4’-methylenedianiline 15 (I) IUR Naphthalene 30 (I) chronic RfC

POM-PAHs 5 : Benzo(a)pyrene Benzo(a)anthracene Benzo(b)fluoranthene Benzo(k) fluoranthene Chrysene Dibenz(a,h)anthracene Indeno(1,2,3-cd)pyrene ng/m 3
6,400 (I)
64,000 (I)
64,000 (I)
64,000 (I)
640,000 (I)

5,800 (I)
64,000 (I) IUR

“

“

“

“

“

“ Diisocyanates μ g/m 3
1,6-hexamethylene diisocyanate 0.2 (I) inter. MRL Methylenediphenyl diisocyanate 6 (I) chronic RfC 2,4-toluene diisocyanate 0.7 (I) chronic RfC

of 100-in-a-million should or dinarily be the upper end of the range of acceptability, with ri sks increasing above this benchmark becoming presumptively less acceptabl e under the HAP program. Additionally, in the Superfund program, acceptable exposure levels for known or suspected lin ear carcinogens are generally those that, using information on the relationship between dose and response, represent an excess upper-bound lifetime

individual cancer risk between 10 − 4 and 10 − 6 [e.g., see 40 CFR 300.430(e)(2)(i)(A)(2)].

m

Where the OAQPS table on web did not represent the most current information, the information was updated.09/10/09

7 of 24 Notes for Table 1

1 Values derived for this document, or for which units conversions were performed are assigned the same number of significant figures as those specified in the source value.

2 Metal samples will be of 2 different types: PM 10 and total suspended particles (TSP). With the exception of lead (for which the NAAQS was developed with explicit recognition of non-inhalation exposure pathways), metals screening levels are more suited for use with the concentration of metal in particles captured in a PM 10 sample.

3 The superscript (I) indicates where an intermediate duration exposure screening levels has been assigned as a surrogate in lieu of a short-term screening level.

4 This value for lead is the level of the NAAQS, which is in terms of a 3-month average level of lead in TSP.

5 PAHs are components of the HAP polycyclic organic matt er (POM). The PAH analytes listed here are those which EPA has identified as carcinogens, and for which inhalation unit risk estimates are available (from the OAQPS Toxicity Table, per section 3.3.b above)). In assessing carcinogenicity for chemicals concluded to be carcinogenic by a mutagenic mode of action and for which early lifestage dose-response information is not available, EPA recommends use of age-dependent adjustment factors (ADAFs) which effectively increase the potency when applied to the first 16 years of age (USEPA, 2005). Dibenz[a,h] anthracene (DBA) and benzo[a]pyrene (BaP), and the other PAHs for which IURs are indexed to that of BaP are considered by EPA to act by mutagenic modes of action (Farland, 2006). In considering potential use of ADAFs in the context of the individual sample screening levels, we recognize several considerations: (1) the objective for the sample screening levels is a short-term exposure estimate (on the order of weeks), (2) application of EPA’s traditional cancer risk assessment methods to such short periods is inherently uncertain, (3) the sample screening levels for these PAHs are actually surrogates for short-term levels and have been derived for a 1-year exposure, (4) the full data analysis for each school (see section 5) will consider potential risk of chronic exposure, and (5) if in the calculation of these levels, we had substituted a short-term exposure duration (e.g., 2 weeks), their values would be increased by a factor of 20, which is more than twice the value of the highest ADAF. Thus, rather than implement a cancer risk calculation specific to a 2-week duration exposure, which is not generally recommended by EPA guidance, we have reta ined the 1-year values and recognize that they are appropriat ely protective of shorter-term exposures with a potential for increased early-life susceptibility.

4. Pollutant-specific Health Effects Information

As mentioned in the previous sections, fi ndings of sample measurements above the individual sample screening levels will be given closer attention to confirm sample results, to assess a potential for unusual circumstances at ne arby sources, and to assess the potential for any immediate health concerns for the e xposed population. Add itionally, longer-term concentration estimates developed in the analys is of the full set of results for a school (see section 5 below) that are above long-term co mparison levels (particu larly in the case of noncancer-based comparison levels) will also be given close attention. In assessing the potential for any health concerns regarding the reported levels, we will be considering the health effects and toxicity information availabl e for that pollutant and the details associated with the derivation of the particular screeni ng or comparison level, as well as the likely exposure circumstances at the monitored location. The type of health effects and toxicity information to be considered for a particular pol lutant would be expected to include the type of effects and exposure conditions (inc luding duration, frequency and inhalation concentrations) with which they are associate d, as well as the confidence level and type and magnitude of uncertainty asso ciated with applicable refe rence or toxicity values.

Sources of information on toxicity and health ef fects that may be cons ulted include, but are not necessarily limited to, materials developed by:09/10/09

8 of 24  ATSDR, including their Toxicological Profiles, ToxGuides TM , Case Studies in Environmental Medicine, Medical Manageme nt Guidelines for Acute Chemical Exposures and Public Health Statements ;

 EPA, including the OAQPS Health Effect s Notebook, the OAQPS Air Toxics Risk Assessment library and toxicity tables, the Integrated Risk Information System, and technical support documents for acute exposure guideline levels; and

 American Industrial Hygiene Association, th e American Conference of Governmental Industrial Hygienists, the National Institute of Occupational Safety and Health and the Occupational Safety and Health Administration.

5. Development of Long-term Comparison Levels

5.1 Background and Objectives for Use of Comparison Levels

The majority of schools being monitored in th is initiative were sele cted based on modeling analyses that indicated the poten tial for annual average air concen trations of some HAPs (air toxics) to be of particular concern based on approaches that are commonly used in the air toxics program for considering potential for long-term risk. For example, these analyses suggested annual average concentrations of some air toxics to be greate r than long-term riskbased concentrations associated with an additi onal cancer risk greater than 1-in-10,000 or a

hazard index on the order of or above 10. Th ese long-term risk-based concentrations presume continuous (all-day, all-year) exposure ov er a lifetime. To make projections of air concentrations, the modeling analyses combined estimates of air t oxics emissions from industrial, motor vehicle and other sources, w ith past measurements of winds, and other meteorological factors that can influence air co ncentrations, from a w eather station in the general area. In some cases, the weather stati on was very close (within a few miles) but in other cases, it was much further away (e.g., up to 60 miles), which may contribute to quite different conditions being modeled than actua lly exist at the school. The modeling analyses are intended to be used to prioriti ze locations for further investigation.

The primary objective of this initiative is to investigate - th rough monitoring air concentrations of the key HAPs at each school over a 2-3 month period - whether the levels measured and associated longer-term concentrat ion estimates are of a magnitude, in light of health risk-based criteria, for which follow-up activities may need to be considered. To evaluate the monitoring results consistent with this objective, we devel oped health risk-based air concentrations (the long-term comparison levels described below) for each monitored pollutant using established EPA methodology an d practices for health risk assessment n and, in the case of cancer risk, consistent with the implied level of risk c onsidered in identifying schools for monitoring. Consistent with the long-term or chronic focus of the modeling analyses based on which these schools were sele cted for monitoring, we intend to analyze the complete dataset of measured concentrations using routine statistical tools to derive a 95 percent confidence interval fo r the estimate of longer-term average concentration for each

n While this EPA initiative will rely on EPA methodology, practices, assessments and risk policy considerations, we recognize that individual state methods, practices and policies may differ and subsequent analyses of the monitoring data by state agencies may draw additional or varying conclusions.09/10/09

9 of 24 HAP monitored at a given school. This project ed range (most particularly the upper end of the range) will be compared to the long-term comparison levels. The analysis of the air concentrations will also include a consideration of the potential for cumulative multiple pollutant impacts in drawing conclusions regarding air toxics at each location. o

In drawing conclusions regarding potential follow-up activities for a particular school location EPA will evaluate the air quality information provided by the full monitoring dataset, in light of various ot her types of information and cons iderations pertinent to the air quality at each location. For the purposes of pr oviding context, some quite general examples of key considerations and poten tial resulting decisions are de scribed in Table 4 below.

In general, where the monitoring results in dicate estimates of longer-term average

concentrations that are a bove the comparison levels – i.e., above the cancer-based comparison levels or notably above the non cancer-based comparison levels - we will

consider the need for foll ow-up actions such as:

 Additional monitoring of air concentra tions and/or meteorology in the area,

 Evaluation of potentially contributing sources to help us confirm their emissions and identify what options (regulatory and otherwise) may be available to us to achieve emissions reductions, and

 Evaluation of actions being ta ken or planned nationally, re gionally or locally that may achieve emission and or exposure reductions. An example of this would be the type of ubiquitous emi ssions from mobile sources.

Where the monitoring data analyses do not project longer-term average concentration estimates above the comparison levels, we will further analyze the dataset to describe what it indicates in light of other crit eria and information commonly used in prioritizing state, local and national air toxics program activities. St ate, local and national programs often develop longer term monitoring data sets in order to better characterize pollutants near particular sources. The 2-3 month dataset developed under this initiative will be helpful to those programs in setting priorities for longer term monitoring projects. The intent of this analysis is to make this 2-3 month monitoring dataset as useful as possible to state, local and national air toxics program in their longer term efforts to improve air qua lity nationally. To that end, this analysis will:

 Describe the air toxics measurements in terms of potential longer-term concentrations, and, as available, compar e the measurements to monitoring data from national monitoring programs.

 Describe the meteorological data by considering conditi ons on sampling days as compared to those over all the days with in the 2-3 month monitoring period and what conditions might be expected over the longer-term, as indicated, for example by information from a nearby weather station.

o As this analysis of a 2-3 month monitoring dataset is not intended to be a full risk assessment, consideration of potential multiple pollutant impacts may differ among site s. For example, in instances where no individual pollutant appears to be present above its comparison level, we will also check for the presence of multiple pollutants at levels just below their respective comparison levels (giving a higher priority to such instances).09/10/09

10 of 24  Describe available information regardi ng activities and emissions at the nearby source(s) of interest, such as that obtai ned from public databases such as TRI

and/or consultation with the local air pollution authority.

5.2 Long-term Comparison Levels

The risk or hazard levels considered in interp reting modeling analysis results with regard to identifying schools for monitoring under this initiative (e.g., 1-in- 10,000 cancer risk and hazard index of 1) derive from aspects of the framework for regulatory decisions in the Clean Air Act (CAA) residual risk program for stati onary sources of air toxics (USEPA, 1999; 70 FR 19992). p While the CAA identifies different crite ria for different types of air sources, with technological feasibility being the key criterion for deci sions on controlling air toxics from mobile sources (e.g., cars and trucks), in the risk management framework for the residual risk program, regulatory actions may generally be considered when estimated

ambient concentrations from the source emissi ons being assessed are equal to a continuous lifetime exposure concentration as sociated with an estimated in crease in lifetime cancer risk greater than 100-in-a-million (or 1-in-10,000). The 100-in-a-million cancer risk level is the approximate upper end of the range that is co mmonly described in EPA risk-based decision making (see footnote l on page 5). The lowe r end of the range is 1-in-a-million.

In our analysis of the air toxics measuremen ts at each school, we recognize two areas of interest. First and most importantly, as descri bed in section 5.1 above, we are interested in identifying circumstances for which follow-up ac tivities need to be considered (i.e., air

concentrations at or above levels considered in identifying schools fo r monitoring under this initiative, such as those for which long-term e xposure is associated with 100-in-a million or greater cancer risk). In addressing this most im portant area of focus, we developed long-term health risk-related comparison levels based on cancer risk using the 100-in-a million level of additional risk (see below). This is consiste nt with criteria that were considered in identifying schools for this monitoring. Sec ondly, as we are intere sted in making these monitoring data as useful as possible to ongoing state, local and national air toxics programs in their air quality improvement activities, we al so intend to describe findings in light of other criteria that may indicate the potential for longer-term air concen trations that while somewhat lower, may still be of a magnitude that would inform EPA, state and local decision-making on risk reduction ac tions for air toxics more broa dly. In our analyses of the monitoring data, we intend to also provide inform ation useful to this second area of interest, such as noting how longer-term concentration esti mates relate to 10% or 1% of the cancerbased comparison level.

With regard to effects other than cancer, EPA’ s residual risk program for stationary sources

of air toxics has not establis hed a strict regulato ry decision framework. Secondly, while EPA develops and uses estimates of cancer risk pe r concentration of life time continuous exposure to carcinogenic air toxics in assessing potential ca ncer risk (and in derivi ng cancer risk-based

p Section 112 of the Clean Air Act describes a two-step approach for regulating categor ies of stationary sources of HAPs. In the first step, EPA set technology-based st andards for all categories. In the second step, EPA is required to assess the residual risk remaining in areas near these sources and where necessary set additional source standards. This second step is re ferred to as the residual risk program.09/10/09

11 of 24 concentrations), we use a different type of tool for analyses that consider the potential for risk of other (noncancer) health effects. This noncancer assessment tool is the reference concentration (RfC) or comparable value. The RfC is a continuous inhalation estimate for the human population, including sensitive subgroups, that is likely to be without appreciable

risk of adverse noncancer effects over a lifetime. The RfC is more informative with regard to exposures that are below it than those above it. That is, an Rf C is not a direct estimator of risk but rather a reference poi nt to gauge the potential for e ffects. Lifetime or chronic exposures at or below the RfC are concluded to be without significant risk of adverse effects. Lifetime exposures above the RfC, however, do not necessarily indicate a risk of adverse health effect. But with such exposures incr easingly above the RfC, there is an increasing potential for risk of effects. This potential varies depending on the pollutant and information specific to that pollutant. Accordingly, we commonly use the RfC as a benchmark in considering potential concern for air toxics exposures posin g risk of noncancer effects, recognizing its more direct strengt h in interpretations regarding e xposures at or below it. For example, noncancer impacts associ ated with projected long-term exposures equal to or below the RfC are currently being give n little regulatory attention in the residual risk program. Situations where projected long-term exposures are above the RfC may be further considered for additional regulation in light of other info rmation, such as information specific to the pollutant and uncertainties in the assessment.

This difference in how we assess potential noncancer effects and can cer risk affects our

consideration of the two areas of focus men tioned above. As we do not have an upper and

lower end of an established reference ri sk range to draw on for noncancer effects concentrations, our analyses involving the noncancer comparison levels take this into account through recognizing that longer-te rm average concentration estim ates that are appreciably above the noncancer comparison level (e.g., by a factor of 5-10 or more) may be more relevant to gauging significance for health concer ns than estimates falling much closer to or below this comparison level. That is, for some pollutants, a situation where the noncancer comparison level is exceeded by a factor on the or der of 10 or more may be more relevant to consider for the purposes of our primary obj ective for this study, than one where the noncancer comparison level is only just exceed ed. Thus, in drawing conclusions about potential concerns associated with estimated longer-term average concentration estimates higher than the long-term comparison level, we intend to consider a variety of factors, including those specific to the site or sources involved whic h might influence exposures (e.g., pending source actions), as well as factors partic ular to the health effects information (e.g., see section 4) including: the endpoints on whic h the RfC is based and our confidence in the RfC, its underlying database and the principa l study; whether or not the RfC represents

current methods and current information for th e chemical, and; the magnitude of quantitative uncertainty associated with the RfC. q As a result, concerns regarding pote ntial health impacts associated with estimated longer-ter m average concentrations above the noncancerbased comparison level may vary in light of factors other than or in addition to the amount by

which the level is exceeded.

qFor example, derivation of the RfCs for acrolein and benzene included division of the exposure concentrations associated with the critical effect by cumulative uncertainty factors of 1000 and 300, respectively. For these pollutants, levels at which health effects have been observed are more than 10-fold higher than the RfCs.09/10/09

12 of 24 In summary, depending on the information avai lable for each pollutant, two types of longterm comparison levels have been derived fo r comparison to the projected range of longerterm average ambient concentration of each key pollutant at each school (Table 2). r

 The cancer-based comparison level is the estimated continuo us (24 hours a day, daily), lifetime exposure concentration associated with an estimated 100-in-a-million lifetime

cancer risk s

.

 The noncancer-based comparison level is the EPA Reference Concentration (RfC) or a comparable value t , which is the estimated con tinuous (24 hours-per-day daily) exposure concentration considered likely to be without adverse effects over a lifetime. In developing or identifying these comparison levels, we have given priority to use of relevant and appropriate air standards and EP A risk assessment guidance and precedents. These levels are based upon the most recent assessments of potent ial toxicity of the monitored toxic air pollutants by EPA, and, as needed, the U.S. Agency for Toxic Substances and Disease Registry, and the Ca lifornia EPA. These agencies recognize the need to account for potential differences in sens itivity or susceptib ility of different groups (e.g., asthmatics) or lifestages/ages (e.g., young child ren or the elderly) to a part icular pollutant’s effects so that the resulting comparison leve ls are relevant for these pote ntially sensitive groups as well as the broader population. Further, the comp arison levels are based on exposure to the pollutants all day, every day over a lifetime. u

5.3 Interpretation of Monitoring Results in Light of Comparison Levels

The report for each school that describes the an alysis of the full monitoring dataset collected at each school (the school-specific report ), will include discussion of all of the information collected as part of this initiative, includi ng the meteorological measurements, information regarding nearby sources as well as the chemical concentration measurements. As mentioned above, analysis of the chemical concentration measurements will include

consideration of what the full monitoring dataset indicates withregard to potential longerterm levels of the monitored pollutant. In doing this we will calculate the mean concentration for each pollutant during the mon itoring period along with the 95% confidence

limits on the mean which we will then use as an estimate of longer-term concentration in

r Comparison levels will be developed consistent with th e method described here for use in considering results

for other HAPs monitored at each school.

s This is derived by dividing 10 -4 by the inhalation unit risk (IUR) value for a pollutant. IURs were taken from OAQPS toxicity table 2 ( http://www.epa.gov/ttn/atw/toxsource/summary.html ). In the case of the chemicals listed here as PAHs, which EPA considers to be carcinogenic by a mutagenic mode of action, either by explicit finding or by indirect finding due to the recognition of BaP as an index for IUR derivation, an additional step is taken as recommended by EPA guidance. Derivation of the cancer-based comparison levels for these pollutants included division by a factor of approximately 1.6 reflecting the application of age-dependent adjustment factors which effectively increase the potency when ap plied to the first 16 years of age (USEPA, 2005).

t Where EPA Reference Concentrations are unavailable, ATSDR chronic Minimal Risk Levels or California EPA chronic Reference Exposure levels are substituted in th at order, consistent with the hierarchy implemented in the OAQPS toxicity table 2 ( http://www.epa.gov/ttn/atw /toxsource/summary.html ). The term “RfC” is used here to indicate any of these values (which are similarly derived and defined).

u This exposure assumption is explicit in its impact on derivation of the cancer-bas ed comparison levels, such that an alternate assumption such as exposure limited to only childhood years would have resulted in higher (less protective) comparison levels.09/10/09

13 of 24 considering the implications of the dataset with regard to longer-term levels. The paragraphs below provide a general descrip tion of how we intend to consid er these summary statistics

that describe the measurements at a school in light of the comparison le vels described in the

sections above.

Cancer-based Comparison Levels: Air toxics for which the upper 95% confidence limit on

the mean concentration falls a bove the cancer-based comparison le vel will be fully discussed in the school-specific report and may be cons idered a high priority for potential follow-up activities in light of the full set of information av ailable for that site. Air toxics for which the upper 95% confidence limit falls below 1% of the comparison level (i.e., those for which longer-term average concentration estimat es are below the corresponding 1-in-1-million cancer risk based concentration) are genera lly considered a low priority for follow-up activity. Situations where the summary statisti cs for a pollutant are below the cancer-based comparison level but above 1% of that level wi ll be fully discussed in the school-specific

report.

Noncancer-based Comparison Levels: Air toxics for which the upper 95% confidence limit

on the mean concentration is near or below th e noncancer-based comparison level (i.e., those for which longer-term average concentration esti mates are below a long-term health-related reference concentration) are generally of low c oncern and will generally be considered a low priority for follow-up activity. Pollutants for which the 95% confidence limits extend appreciably above the noncancer -based comparison level will be fully discussed in the school-specific report and may be considered a priority for follow-up activity, if indicated in light of the full set of information available for the pollutant v and the site. Interpretation in the case of lead entails additional specific cons iderations related to the use of the national ambient air quality standard as the comparison level.

Multi-pollutant Cumulative Risk: The school-specific report will also consider and discuss the potential for multiple monitore d pollutants (e.g., in addition to the key pollutant(s)) to be present at levels that might c ontribute to a potential for cumu lative risk, particularly in situations where multiple pollutants are pres ent at longer-term leve ls just below their respective comparison levels.

v Such information includes that described in section 4 above.09/10/09

14 of 24 Table 2. Long-term Comparison Levels for Key ( aka “driver”) Pollutants.

Analyte Cancer-based Comparison

Level 1 source Noncancerbased Comparison

Level 1 source 2004-07

NATTS 2
Arithmetic Mean (Median) [Maximum]

Metals 3 n g/m 3 n g/m 3 PM 10 Metals ng/m 3 Arsenic (PM 10 focus) 23 IUR 15 REL 1.1 (0.69) [48] Chromium-hexavalent 8.3 IUR 100 RfC 0.05 (0.03) [3] Cobalt (PM 10 focus)
- 100 MRL 0.32 (0.17) [20]

Lead 4 -TSP
- 150 3 NAAQS 5.6 (3.5) [751] Manganese (PM 10 focus)
- 50 RfC 11 (4.8) [410] Nickel (PM 10 focus) 420 5 IUR 90 MRL 2.6 (1.8) [110] VOCs/Carbonyls μ g/m 3 μ g/m 3 μ g/m 3 Acetaldehyde 45 IUR 9 RfC 1.9 (1.4) [93]

Acrolein 6 0.02 6 RfC 6 0.63 (0.44) [7.3] Benzene 13 IUR 30 RfC 1.1 (0.86)[10] 1,3-Butadiene 3.3 IUR 2 RfC 0.15 (0.09) [16] 4,4’-methylenedianiline 20 Cal-IUR 0.22 REL -- Naphthalene 3 Cal-IUR 2.9 RfC

PAHs 7 : Benzo(a)pyrene Benzo(a)anthracene Benzo(b)fluoranthene Benzo(k) fluoranthene Chrysene Dibenz(a,h)anthracene Indeno(1,2,3-cd)pyrene n g/m 3

57

570

570

570 5,700

52

570 IUR

IUR

IUR

IUR

IUR

IUR

IUR Diisocyanates μ g/m 3 μ g/m 3 -- 1,6-hexamethylene diisocyanate 0.01 RfC -- Methylenediphenyl diisocyanate 0.6 RfC -- 2,4-toluene diisocyanate 9.1 Cal-IUR 0.07 RfC --

Table Notes

1 Values derived for this document, or for which units conversions were performed are shown here with the same number of significant figures as those specified in the source value.

2 NATTS concentrations, presented to provide a reference for ambient levels of these pollutants, have been rounded to 2 significant figures.

3 Metal samples will be of 2 different types: PM 10 and total suspended particles (TSP). With the exception of lead (for which the NAAQS was developed with explicit recognition of non-inhalation exposure pathways), metals comparison levels may be more suited for use with the concentration of metal in particles captured in a PM 10 sample. While a Pb-PM 10 average above the Pb comparison level is a finding of similar (or greater) interest than that for Pb-TSP, long-term averages for other metals in TSP that fall above a comparison level primarily indicate

the need to consider results for that metal in PM 10 on a case-by-case basis.

4 The value here is the level of the NAAQS, which is in terms of a 3-month average level of lead in TSP.

5 The value here is based on the IRIS IUR for nickel refinery dust.

6 The comparison level shown for acrolein is the EPA RfC which is set below a level associated with health effects. The RfC is set as a factor of 1000 below an exposure concentration associated with sensitive nasal effects in laboratory animals. Since the EPA RfC wa s derived, the California EPA has derived a chronic REL09/10/09

15 of 24 based on more recently available information on acrolein and its effects. The Ca l-EPA REL, which is 0.35 ug/m 3

, is somewhat more than a factor of 100 below the level associated with effects in the more recently available study.

7 The PAHs listed here are those identified as carcinogens, and for which inhalation unit risk estimates are available (from OAQPS Toxicity Table per section 3.3.b above)). The cancer-based comparison levels for these pollutants reflect EPA recommended appl ication of age-dependent adjustment factors to reflect a potential for increased susceptibility to these substances in the first 16 years of life.

Table 4. General examples of key considera tions and potential follow-up conclusions.

 If a key source of air pollution near a particular school is known to have temporarily ceased its operations during a significant portion of the monitoring period (e.g., due to temporary closure, periodic shutdowns, reduced operational capacity , etc.), EPA may not be able to draw conclusions from the initial 60-90 day dataset regarding the potential for “usual” air toxics levels to pose a potential for chronic health impacts and may wish to consider additional monitoring if and when the key source or sources restart operations

 If the windrose during the sampling days shows significantly less windflow in the source-to-school direction as compared to what is seen across the full monitoring period or what might be expected over the longer term, EPA may choose to contin ue monitoring even if measurem ents suggest impacts are low

 Frequent rainfall throughout the moni toring period may cause EPA to decide to continue monitoring even if measurements suggest impacts are low

 If the concentrations of the key pollutants are all low, but the monitoring captures significant concentrations of an unexpected pollutant, EPA may choose to continue moni toring for that pollutant

 If the entire estimated long-term concentration range for each key pollutant falls below the respective longterm comparison levels and the wind measurements indicate inclusion of sampling dates with winds in the direction of primary sources and th e source activity has been consistent with usual conditions, EPA may conclude that there is low potential for significant risk of chronic health impacts associated with air toxics at that school and recommend that we cease monitoring there.

 For pollutants where the measured concentrations are of a magnitude that may indicate some potential for chronic health concerns but where the measurements correspond to typical historic levels nationwide (e.g., this may be the case for acrolein and perhaps some others), EPA will gi ve particular consideration to the school-specific data in light of the data for situations nationally, any associated national activities that are underway and information about other activities to address the pollutant sources. Such information will inform conclusions regarding next steps at the school. Based on this consideratio n, EPA may, for example, focus follow-up activities on a range of areas potentially including making the public aware of the available information, working with state and local partners to consider steps that may be available to us to reduce the pollutants locally, and/or examining how national activities underway may reduce the pollutants in the future.

 For pollutants where measured levels are indicative of some potential for chronic impacts (for continuous long-term exposure scenarios), but where requirements are in place to reduce key source emissions within next year or so (e.g., consent order), EPA may indicate that while this school’s air ha s levels that might be of potential concern over a long term, source requirements are expected to preclude the occurrence of these levels over the long-term, and may conclude to revisit monitoring on some altered longer-term schedule.

 If the entire estimated long-term concentration range for any key pollutant falls above the long-term comparison levels (and concentrations are not typical nationally and we have no information indicating activities in place to reduce concen trations in future), EPA may conclude that the potential for chronic health impacts of concern associated with that pollutant at that school indicate a need to pursue (in concert with the State or local air agency) options for emission redu ctions of that pollutant at the key source(s), while also continuing monitoring to more accurately characterize long-term concentrations and track the progress

of emission reduction efforts.09/10/09

16 of 24 REFERENCES

ATSDR. 2008. MRLs. http://www.atsdr.cdc.gov/mrls/ . December.

Cal-EPA 2008. RELs. http://www.oehha.ca.gov/air/hot_spots/index.html . December 18.

Farland. 2006. Implementation of the Cancer Guidelines and Accompanying Supplemental Guidance – Science Policy Council Cancer Guidelines Implementation Workgroup Communication II: Performing Risk Assessments that include Carcinogens Described in

the Supplemental Guidance as having a Mutagenic Mode of Action. Memorandum to Science Policy Council and Science Policy Council Steering Committee. June 14, 2006.

OAQPS. 2007. Toxicity Table. http://www.epa.gov/ttn/atw/toxsource/summary.html

U.S. EPA Region III. 1997. Hazard Evaluation Handbook. A Guide to Removal Actions. EPA

903/B-97-006.

USEPA 1999. Residual Risk Re port to Congress. EPA-453/R- 99-001. Office of Air Quality Planning and Standards, Resear ch Triangle Park, NC. March.

USEPA 2005. Supplemental Guidance for Assessing Su sceptibility from Early-Life Exposure to Carcinogens. EPA/630/R-03/003F. Risk Assessment Forum, Washington DC.

USEPA. 2009. Information Risk Integrated System. http://cfpub.epa.gov/ncea/iris/index.cfm

. April.09/10/09

17 of 24 APPENDIX A. Individual Sample Screening Levels for Additional (non-key) HAP Analytes. The methodology and important considerations for their interpretation aredescribed in

section 3 above and the foot notes following the table.

Additional HAP Analytes Individual Sample Screening Level 1 Value from which Screening Level Derived

Metals 2 ng/m 3
Antimony 7 (PM 10 focus) 2,000 (I) 3 chronic RfC Beryllium (PM 10 focus) 20 (I) chronic RfC Cadmium (PM 10 focus) 30 acute MRL Mercury (elemental) 8 3,000 (I) chronic RfC Selenium (PM 10 focus) 20,000 (I) chronic REL VOCs/Carbonyls μ g/m 3

Acetonitrile 600 (I) chronic RfC Acrylonitrile 200 acute MRL Benzyl chloride 140 (I) IUR Bromoform 6,400 (I) IUR

Carbon disulfide 7000 (I) chronic RfC

Carbon Tetrachloride 200 (I) inter. MRL Chlorobenzene 10,000 (I) chronic REL

Chloroform 500 acute MRL Chloroprene 70 (I) chronic RfC
1,4-Dichlorobenzene 10000 acute MRL 1,3-Dichloropropene 40 (I) inter. MRL Ethyl acrylate 7000 [9] [9]
Ethyl benzene 40,000 acute MRL Chloroethane (ethyl chloride) 40,000 acute MRL Ethylene dibromide 12 (I) IUR Ethylene dichloride 270 (I) IUR Ethylidene dichloride (1,1-dichloroethane 4400 (I) HEAST chronic RfC Formaldehyde 50 acute MRL

Hexachlorobutadiene 320 (I) IUR Bromomethane (methyl br omide) 200 acute MRL Chloromethane (methyl chloride) 1000 acute MRL 1,1,1-Trichloroethane (methyl chloroform) 10,000 acute MRL Methyl isobutyl ketone 30,000 (I) chronic RfC Methyl methacrylate 7000 (I) chronic RfC Methyl tert-butyl ether 7,000 acute MRL Methylene Chloride 2000 acute MRL Propionaldehyde 80 (I) chronic RfC

μ g/m 3 Propylene dichloride (1,2-dichloropropane) 200 acute MRL Styrene 9,000 acute MRL
1,1,2,2-Tetrachloroethane 120 (I) IUR09/10/09

18 of 24 Additional HAP Analytes Individual Sample Screening Level 1 Value from which Screening Level Derived
Tetrachloroethene 1,400 acute MRL
Toluene 4,000 acute MRL
1,2,4-Trichlorobenzene 2,000 (I) chronic RfC
1,1,2-Trichloroethane 440 (I) IUR Trichloroethylene 10,000 acute MRL Vinyl Chloride 1,000 acute. MRL Vinylidene chloride (1,1-dichloroethylene) 80 (I) inter. MRL Xylene 9,000 acute MRL
Notes for Appendix A

1 Values derived for this document, or for which units conversions were performed are assigned the same number of significant figures as those specified in the source value.

2 Metal samples will be of 2 different types: PM 10 and total suspended particles (TSP) . With the exception of lead (for which the NAAQS was developed with explicit recognition of non-inhalation exposure pathways), metals screening levels may be more suited for use with the concentration of metal in particles captured in a PM 10 sample.

While a Pb-PM 10 sample above the Pb screening level is a finding of similar (or greater) interest than that for Pb-TSP, results for other metals in TSP that fall above a screening level may primarily indicate the need to consider results for

that metal in PM 10 on a case-by-case basis.

3 The superscript (I) indicates where an intermediate duration exposure screening levels has been assigned as a surrogate in lieu of a short-term screening level.

4 This value for lead is the level of the NAAQS, which is in terms of a 3-month average level of lead in TSP.

5 As neither an ATSDR intermediate MRL or a chronic value from the OAQPS table is available for total nickel, the screening level provided here is that for nickel refinery dust.

6 PAHs are components of the HAP polycyclic organic matter (POM). The PAH analytes listed here are those which EPA has identified as carcinogens, and for which inhalation unit risk esti mates are available (from the OAQPS Toxicity Table, per section 3.3.b above)). In assessing carcinogenicity for chemicals concluded to be carcinogenic by a mutagenic mode of action and for which early lifestage dose-response information is not available, EPA recommends use of age-dependent adjustment factors (ADAFs) which effectively increase the potency when applied to the first 16 years of age (USEPA, 2005). Dibenz[a,h] anthracene (DBA) and benzo[a]py rene (BaP), and the other

PAHs for which IURs are indexed to that of BaP are co nsidered by EPA to act by mutagenic modes of action (Farland, 2006). In considering potential use of ADAFs in the context of the individual sample screening levels, we recognize several considerations: (1) the objective for the sample screening levels is a short-term exposure estimate (on the order of weeks), (2) application of EPA’s traditional cancer risk assessment methods to such short periods is inherently uncertain, (3) the sample screening levels for these PAHs are actually surrogates for short-term levels and have been derived for a 1-year exposure, (4) the full data analysis for each school (see section 5) will consider potential risk of chronic exposure, and (5) if in the calculation of these levels, we had substituted a short-term exposure duration (e.g., 2 weeks), their values would be increased by a factor of 20, which is more than twice the value of the highest ADAF. Thus, rather than implement a cancer risk calculation specific to a 2-week duration exposure, which is not generally recommended by EPA guidance , we have retained the 1- year values and recognize that they are appropriately pr otective of shorter-term exposures with a pot ential for increased early-life susceptibility.

7 As neither an ATSDR intermediate MRL nor a chronic assessment from the OAQPS toxicity table is available for total antimony, the screening level provided here, and limited to use in this project, is that for antimony trioxide.

8 As neither an ATSDR intermediate MRL nor a chronic assessment from the OAQPS toxicity table (per Section 3.3) is available for particulate mercury, the screening level provided here is that for elemental mercury, which is expected to be lower than that which would be pertinent to particulate mercury (if one existed).

9 For ethyl acrylate, ATSDR has not established any MRLs of any exposure duration and OAQPS has identified no chronic dose-response values (http://www.epa.gov/ttn/atw /toxsource/summary.html). The value provided as a surrogate sample screening level is the screening level for me thyl methacrylate, which is of the same chemical class09/10/09

19 of 24 and which is lower than that indicated by other available hea lth effects information. In considering additional health effects information for this pollutant, emergency planning guideline levels (Acute Exposure Guideline Levels and Emergency Response Planning Guidelines), developed for various levels of severity and durations of exposure up to 8 hours, and their basis were reviewed. Additionally, chronic exposure values developed by the Occupational Safety and Health Administration and the American Conference of Governmental Industrial Hygienists (ACGIH) were reviewed, while recognizing that these values were developed for use in workplace environments and are not intended for ambient, environmental exposures of the general population. For example, the ACGIH threshold limit values (TLVs), while developed for use in considering time -weighted average wo rker exposures over an 8-hour shift, are based on recognition of repeated workday exposures in the context of 40-hour work weeks throughout a worker’s career. The ACGIH TLV of 5 ppm (20 mg/m 3 ) is based on minimizing irritant effects of chronic exposures to ethyl acrylate, including such effects to the respiratory tract, skin, eyes, and gastrointestinal tract (as documented in

Threshold Limit Values for Chemical Substances and Ph ysical Agents and Biological Exposure Indices, ACGIH) . As might be expected given the long-term exposure aspect of its basis, the ACGIH TLV is the lowest among the values considered here. The surrogate screening level shown in the table above, however, is lower than the ACGIH TLV.09/10/09

20 of 24 Appendix B. Individual Sample Screening Levels for non-HAPs

As mentioned in section 1 above, the ambient air monitoring methods being used in this project for HAPs of interest also produce measuremen ts for several non-HAPs. Some of these chemicals are well studied and individual sample screening levels (as de scribed in section 2 above) have been developed for them. 23 These are presented in Table B-1 below.

Table B-1. Analytes that are not CAA Section 112 Hazardous Air Pollutants for which data support development of sample screen ing levels

Additional (non-HAP) Analytes CAS # Individual Sample Screening Level (ug/m 3 ) 1 Value from which Screening Level

Derived 2003-2007 Monitoring Data in

AQS, Maximum (median) ( μ g/m 3 )

Acetone 67-64-1 62,000 acute MRL 2600 (4 x 10 -3 ) Cis-1,2-dichloroethylene 156-59-2 value for trans isomer 0.52 (ND) Trans-1,2-dichloroethylene 156-60-5 800 acute MRL 0.53 (ND) Methyl ethyl ketone 78-93-3 50,000 (I) chronic RfC 16 (7 x 10 -4 ) Propylene 115-07-1 30,000 (I) chronic REL 3.2 (8 x 10 -4 )

m-dichlorobenzene (1,3-DCB) 541-73-1 10,000** Val for para- isomer (Appendix B) 6.6 x 10 -1 (ND)

For the remaining non-HAP analytes, the available chemical-specific information (including that recognized in section 3 above) and sample screeni ng levels for structurally similar chemicals in Tables 1 or Appendix A (see Table B-2 below) will be considered in reviewing individual sample results.

23 In the case of 1,3-dichlorobenzene, no chemical-specific information useful to assigning a screening level was identified. So the sample screening level for the pa ra-isomer (1,4-DCB), presented in Appendix A above was assigned (see Table A-1).09/10/0921 of 24Table B2. Pollutants for which data limitdevelopment of sample screening levels* (e.g., no EPA, ATSDR or Cal-EPA acute or chronicassessments).Additional (non-HAP)AnalytesCAS #Available information regarding levels of interest(ug/m3)1Structurally similarchemicals2003-2007MonitoringData in AQS,Maximum(median)(μg/m3)Acetylene74-86-2 Lowest concentration at which effects reported is 108μg/m3.CNS depression is most sensitive effect reported – it was usedas anesthetic in 1920s. Use stopped due to explosivecharacteristics. The NIOSH REL, as a ceiling, is 2500 ppm, 3 x106μg/m3(based on concern regarding phosphine whichoccurs in industrial grade acetylene, 2500ppm).There are no straight-chainAlkyne HAPs. The moststructurally similar alkyne,propyne (74-99-7), hasACGIH TLV-TWA of 1000ppm. 1000 ppmacetylene=1x106μg/m3.6.2 x 10-2 *(~3 x 10-3)Bromochloromethane 74-97-5 Lowest exposures in animal studies has been 370 ppm in dogand rat (subchronic [6mo] exposure) – some increased liverweight in rat. The ACGIH TLV-TWA is 200 ppm (106μg/m3).This was developed based on consideration of animalexposure data and concerns regarding CNS and liver effects.1.1x10-1 *(ND)Bromodichloromethane 75-27-4 Lowest exposures indicative of effects in animal studies hasbeen 10 ppm in mice (prechronic [3 week] exposure) – somekidney effects which were notseen in exposures at thisconcentration lasting 13 weeks. The next lower concentrationstudied (3 ppm or 2x104μg/m3) did not show effects in mice at 3weeks or at 13 weeks of exposure (NTP).1.3x10-1(ND)Dibromochloromethane 124-48-1 No inhalation studies identified (HSDB).The sample screening levelfor a structurally similar HAP,chloroform, is 0.1 ppm.Inμg/m3, 0.1 ppm is:500μg/m3bromochloromethane,700μg/m3bromodichloromethane,900μg/m3dibromochloromethane1.7x10-1(ND)09/10/0922 of 24Additional (non-HAP)AnalytesCAS #Available information regarding levels of interest(ug/m3)1Structurally similarchemicals2003-2007MonitoringData in AQS,Maximum(median)(μg/m3)Dichlorodifluoromethane(Freon 12)75-71-8Lowest concentration at which effects reported is 800 ppm (4 x106μg/m3) in guinea pig (subchronic [90day continuous]exposure) – liver pathological changes not seen in dog,monkey, rat or rabbit exposures. The ACGIH TLV-TWA is1000 ppm (5 x 106μg/m3). Sweden has an occupational valueof 500 ppm (2 x 106μg/m3).7 (2.6x10-3)Dichlorotetrafluoroethane(Freon 114)76-14-2 Lowest concentration at which effects reported is 25,000 ppm (μg/m3) in dog (acute exposure) – cardiac arrhythymia. Nosignificant clinical, hematologic, histopathologic changes in ratsand rabbits reported from repeated (2 hr/day; 5 day/wk) chronic(8-9 mos) exposure to 10,000 ppm. The ACGIH TLV-TWA is1000 ppm (7 x 106μg/m3)8.3 (1x10-4)Trichlorotrifluoroethane(Freon 113)76-13-1 Short term exposure to fluorocarbon 113 can occur byinhalation, ingestion, and skin absorption. Inhalation andingestion of fluorocarbon 113 will result in drowsiness,narcosis, central nervous systemdepression and significantimpairment of manual dexterity and vigilance. Irritation of theeyes, nose, throat, and skin can also occur. Breathingconcentrations that are greater than 2000 ppm may causeirregular heartbeat or heart arrest. Concentrations that exceed2000 ppm are considered as immediately dangerous to life andhealth (NIOSH). 1000 ppm (7.6 x 106μg/m3). A similarpurpose standard in Sweden and Germany is 500 ppm (4 x 106μg/m3).0.05 (9 x 10-4)Trichlorofluoromethane(Freon 11)75-69-4 The ACGIH ceiling and the OSHA PEL is 1000ppm (5.6 x 106μg/m3) based on a subchronic animal test NOAEL.Among these four Freons, thelowest health-relatedconcentration identified is 2 x106μg/m331 (1 x 10-3)09/10/0923 of 24Additional (non-HAP)AnalytesCAS #Available information regarding levels of interest(ug/m3)1Structurally similarchemicals2003-2007MonitoringData in AQS,Maximum(median)(μg/m3)Ethyl tert-butyl ether 637-92-3The ACGIH TLV-TWA is 5 ppm (20,000μg/m3).0.4 (ND)Tert-amyl methyl ether 994-05-8The sample screening levelfor a structurally similar HAP,MTBE, is 2 ppm. Inμg/m3, 2ppm is:8000μg/m3ETBE or TAME0.5 (ND)n-octane 111-65-9The NIOSH REL is 75 ppm (350,000μg/m3), on the basis ofweight given to neurotoxic effects associated with hexaneexposures. The ACGIH TLV-TWA is 300 ppm (1,400,000μg/m3), established on the basis of comparison of the acuteresponse to other paraffinic hydrocarbons.The sample screening levelfor a structurally similar HAP,hexane, is 2 ppm. Inμg/m3,2 ppm is:9000μg/m3octane4 (1 x 10-4)1,2,4-trimethylbenzene 95-63-65.7 (3 x 10-4)1,3,5-trimethylbenzene 108-67-8The ACGIH TLV-TWA is 25 ppm (100,000μg/m3) The 8 hrAEGL-1 is 45 ppm.The sample screening levelfor a structurally similar HAP,xylene, is 2 ppm. Inμg/m3, 2ppm is:10,000μg/m31,2,4- or 1,3-5-trimethylbenzene1.9 (8 x 10-5)AldehydesBenzaldehyde 100-52-7 The ACGIH WEEL TWA is 2 ppm . 8.2 (1 x 10-4)Butyr- andIsobutyraldehyde123-72-878-84-2The ACGIH WEEL TWA is 25 ppm (74 mg/m3) 25 (2 x 10-4)Crotonaldehyde 123-73-9 The ACGIH TLV-TWA Ceiling is 0.3 ppm (0.86 mg/m3) toprotect the skin. The NIOSH REL-TWA is 2 ppm (6000μg/m3).The ACGIH TLV-TWA is 2 ppm to protect against therespiratory irritancy effects. The AEGL-1 (8hr)=0.2 ppm.0.8 (1.5 x 10-4)2,5-Dimethylbenzaldehyde 5779-94-2The sample screening levelfor a structurally similar HAP,formaldehyde, is 0.04 ppm.Inμg/m3, 0.04 ppm is:200μg/m3benzaldehyde,2,5-dimethylbenzaldehyde,hexaldehyde,isovaleraldehyde, or the09/10/0924 of 24Additional (non-HAP)AnalytesCAS #Available information regarding levels of interest(ug/m3)1Structurally similarchemicals2003-2007MonitoringData in AQS,Maximum(median)(μg/m3)Hexaldehyde (hexanal) 66-25-15.8 (1.3x10-4)Isovaleraldehyde (3-methylbutanal)590-86-31 (ND)o-, m- and p-tolualdehyde 529-20-4,620-23-5,104-87-00.4(1.5x10-3)Valeraldehyde (pentanal) 110-62-3 The ACGIH TLV-TWA is 50 ppm (176 mg/m3). The NIOSHREL is 50 ppm.tolualdehydes100μg/m3butyraldehydes orvaleraldehyde1.3 (1x10-4)