MEMORANDUM

DATE : May 1 9 , 2014

SUBJECT: Risk Assessment to Determine a Health

- Based Emission Limitation for Acid

Gases for the Clay Ceramics Manufacturing Source Category

FROM: Mark Morris Health and Environmental Impacts Division

Office of Air Quality Planning and Standards

Ted Palma Health and Environmental Impacts Division Office of Air Quality Planning and Standards

Chris Sarsony Health and Environmental Impacts Division Office of Air Quality Planning and Standards

TO: Docket EPA

- HQ

- OAR

- 2013

- 0290

Section 112 (d) (2) of the Clean Air Act (Act) mandates that emission standards be promulgated for sources of hazardous air pollutants, and that the standards “ shall require the maximum degree

of reduction in emissions of the hazardous air pollutants subject to this section (including a prohibition on such emissions, where achievable) that the Administrator, taking into consideration the cost of achieving such emission reduction, and any non

- air quality health and

environmental impacts and energy requirements, determines is achievable for new or existing sources in the category or subcategory to which such emission standard applies ...” The se standards are referred to as Maximum Achievable Control Technology (MACT) standards.

Sec tion 112(d)(4) of the Act states that, “ With respect to pollutants for which a health threshold has been established, the Administrator may consider such threshold level, with an ample margin of safety, when establishing emission standards under this subse ction. ” In other words, for hazardous air pollutants (HAP) with a health threshold, standards may be promulgated under a process different from that otherwise specified in Section 112(d), and these standards are referred

to as health

- based emission limita tions (HBEL). This memorandum documents a risk assessment performed to determine an HBEL for acid gases for the Clay Ceramics Manufacturing source category.2

Summary The purpose of the assessment was to determine a level of emissions that would ensure

h ealth thresholds for acid gases are not exceeded (with an ample margin of safety) at any facility in the source category. To determine this level, unit emissions (one ton per year) of hydrochloric acid (HCl) were assigned to each facility in the source ca tegory , and this level was used as the

emissions input into EPA’s Human Exposure Model (HEM 3 ). Using the unit emissions along with emission release pa rameters for each facility, HEM 3 provide d estimates of ambient

concentrations (and noncancer hazard indic es based on those concentrations ) per unit emissions near the facilities, based on meteorological data near each facility, and at the c ensus block centroid locations used as surrogates for human exposure. Using the highest modeled chronic

concentration for any facility , the unit emissions were scaled up such that an emissions level equivalent to a target

- organ

- specific hazard index (TOSHI) of one (to one significant figure)

could be estimated. This level is 600 tons per year (tpy) of HCl

- equivalent emissio ns, with the equivalency based on the chronic Reference Concentration (RfC) values for the acid gases , and

is equivalent to 420 t py per year of hydrofluoric acid (HF) or 4.5 tpy of chlorine (Cl 2 )

. Because

the 600 tpy level of HCl

- equivalent emissions is ba sed on the chronic RfC values of the acid

gases, the limit ensures that no chronic threshold for any acid gas would be exceeded. To assess the potential for acute health effects and environmental effects from HCl, HF, and Cl 2 , separate

HEM 3 runs were performed for each pollutant at the emissions levels discussed above for each pollutant

.

Facilities Assessed Eight facilities are estimated to be in the Clay Ceramics source category and were

included in this assessment. These facilities are listed in Table 1

.

Table 1 . List of Modeled Facilities Company Name Facility Name Address City State County Marazzi Group S.p.A. Marazzi, Sunnyvale Facility 359 Clay Road Sunnyvale TX Dallas

Dal

- Tile Corp. Dal Italia 3801 Dal

- Tile Road Muskogee OK Muskogee

Mohawk Industries Dal

- Tile El Paso Plant 12001 Railroad
Drive El Paso TX El Paso

Marazzi Group S.p.A. Monarch Ceramic Tile, Inc. 834 Rickwood
Road Florence AL Lauderdale

Florim Ceramiche S.p.A Florim USA 300 International
Blvd Clarksville TN Montgomery

Kohler Co. Kohler, Spartanburg

Plant 4000 South Pine
Street Spartanburg SC Spartanburg

Kohler Co. Kohler, Brownwood
Plant 4601 Hwy 377
South Brownwood TX Brown

Kohler Co. Kohler, Wisconsin
Plant 444 Highland Drive Kohler WI Sheboygan

Emissions and Release Parameters3

As discussed above, unit emissions (1 tpy) of HCl were assigned to each facility, and this level was used as input into HEM3 to estimate the maximum ambient chronic concentration (at census block receptors or other popula ted receptors) for each facility. The emissions of the facility with the highest modeled ambient chronic concentration were scaled up such that they were equivalent to a noncancer TOSHI of one. The resulting emissions level is 600 tpy of HCl

equivalent e missions, which is equivalent to 420 tpy of HF or 4.5 tpy of Cl 2 . A HEM3 run was made for each pollutant’s emissions level to estimate pollutant

- specific acute concentrations and to create model output files needed to estimate environmental risks. No emi ssions multiplier was

used in HEM3 to account for short

- term emissions being higher than the annual tpy level. The resulting acute modeled estimates reflect 1

- hour emissions being simply the annual emissions level divided by 8760 hours per year.

Facility information and emission release parameters used in HEM3 were obtained mostly from Information Collection Request (ICR) data collected in 2008 through 2011. Where there were data gaps, the data were supplemented with information from various data sources, including an earlier 1997 ICR and title V permits. For missing release parameters, conservative default values (e.g., the 25 th percentile of stack height, exit velocity, and temperature) were calculated based on

the data from other facilities. Where it was determined that kilns were shut down, inactive, or area sources (true area or synthetic minor), they were not included in the data. For facilities with multiple stacks, the facilitywide emissions level was divided evenly by the number of stacks. Where multiple kilns share the same stack, the emissions from those kilns were modeled as being emitted from the single stack.

Dispersion Modeling and Estimating Inhalation Exposures

I nhalation exposure concentrations and potential health risks w ere estimated using HEM3, an inhalation risk model that incorporates the American Meteorological Society/EPA Regulatory Model (AERMOD) dispersion modeling system (AERMOD version 1 3350) . The

AERMOD model is a state

- of

- the

- science Gaussian plume dispersion model that is preferred by EPA for modeling point, area, and volume sources of continuous air emissions. 1 The model is

used to estimate annual average ambient concentrations through the simulation of hou r

- by

- hour dispersion from the emission sources into the surrounding atmosphere , and can also be used to

estimate short

- term ambient concentrations, with the shortest averaging time being one hour.

Further details on AERMOD can be found in the AERMOD u ser ’ s g uide

, 2 and further details on HEM3 can be found in the user’s guides for HEM3. 3 For this assessment, annual concentrations were estimated to assess chronic health impacts and the potential for environmental effects, and

1

- hour concentrations were estim ated to assess acute health impacts. Unless otherwise stated in this document, the modeling methodologies used for this assessment are the same as those used in air toxics assessments performed for the Risk and Technology Review (RTR) program.

1 US EPA, 2005. Revision to the Guideline on Air Quality Models: Adoption of a Preferred General Purpose (Flat and Complex Terrain) Dispersion Model and Other Revisions; Final Rule. 40 CFR Part 51. http://www.epa.gov/EPA

- AIR/2005/November/Day

- 09/a21627.htm

. 2 US EPA, 2 004. User ’s guide for the AMS/EPA regulatory model

– AERMOD. EPA

- 454/B

- 03

- 001. http://www.epa.gov/scram001/7thconf/aermod/aermodugb.pdf.

3 http://epa.gov/ttn/fera/human_hem.html#guide

.4

The first step in the application of the HEM3 modeling system is to predict ambient concentrations at locations of interest. The AERMOD model options employed are summarized

in Table 2 and are discussed further below

.

Table 2

. AERMOD V ersion 1 3350 M o del O ptions

Modeling Option Selected Parameter

Type of calculations Hourly a mbient c oncentration

Source type Point

Receptor orientation Polar (13 rings and 16 radials) Discrete (census block centroids and additional residential
receptors )

Terrain characterization Actual from USGS 1/3 a rc s econd NED data

Building downwash Not i ncluded

Plume deposition/depletion Not i ncluded

Urban source option Yes

Meteorology 1 year (2011) NWS from nearest site processed with

AERMET 13350 1

1 Meteorological data processed with the pre

- public release version of AERMET 13350.

See http://www2.epa.gov/fera/download

- human

- exposure

- model

- hem for a complete listing of

meteorol ogical stations.

The HEM3 estimates chronic and acute ambient concentrations at the geographic centroids of census blocks (using the 2010 Census), and at other receptor locations that can be specified by the user. For chronic exposures, t he model accoun ts for the effects of multiple facilities when estimating concentration impacts at each block centroid , and includes only census blocks with at least one resident (i.e., locations where people may reasonably be assumed to reside rather than receptor points at the fenceline of a facility). A mbient concentrations for all averaging times (e.g., 1

- hour, annual) are calculated using modeled one

- hour concentrations at each block centroid. Possible future residential use of currently uninhabited areas is not

con sidered. Census blocks, the finest resolution available in the census data, are typically comprised of approximately 5 0 people or about ten households.

For the facilities included in this assessment, census block locations were evaluated to

determine if they are representative of the residential locations within the blocks. For one facility, a block centroid was located on facility property, and this block was moved to a location that better represents the residential locations associated with the block. There was also one census block with no apparent population, and this block was removed. The census block

ad justments are listed in Table 3

.5

Table 3

. Revised Census Block Centroid Locations for the Clay Ceramics Source Category

Centroid Revisions

Block ID NEI ID New
Latitude New Longitude Comment

481130181041091 32.771973

- 96.568415

010770109005008 Block removed

– no apparent population

One year of meteorological data (2011) w as used for each facility. These data were processed using EPA’s AERMET (version 1 3350 ) program , which is the meteorological data preprocessor for AERMOD. T he ADJ_U* non

- Default BETA option that adjust s the surface friction velocity (u* or ustar) for low wind speed stable conditions was used. The AERMINUTE

pro gra m (version 11325) is a data preprocessor for AERMET, and was used to process 1

- minute wind data to generate hourly average winds for input to AERMET

. The EPA’s AERSURFACE

tool (version 13016) was also used to process land cover data to determine the surface

characteristics for use in AERMET.

Chronic n oncancer health hazards are expressed by comparing a chronic exposure to a reference level as a ratio. The “hazard quotient” (HQ) is the estimated exposure divi ded by a reference level (e.g., the RfC). For a given HAP, exposures at or below the reference level (HQ≤1) are not likely to cause adverse health effects. As exposures increase above the reference level (HQs increasingly greater than 1), the potential f or adverse effects increases

. For a typical risk assessment where multiple pollutants are co

- emitted, we aggreg at e noncancer HQs of HAPs that act by similar toxic modes of action, or (where this information is absent) that affect the same target organ. Th is process creates, for each target organ, a TOSHI, defined as the sum of hazard quotients for individual HAPs that affect the same organ or organ system. Because we performed HEM3 model runs for each acid gas individually, we did not aggregate HQ values o f different acid gases. Of course, multiple acid gas pollutants are emitted at Clay Ceramics facilities, but the 600 tpy level of HCl

- equivalent emissions ensures that a TOSHI of one is not exceeded as long as the HCl

- equivalent emissions do not exceed 60 0 tpy.

Acute Health Risk Screening For the assessment of potential health risks from acute exposures to the acid gases, we performed a screening assessment using conservative assumptions that in combination approximate a worst

- case exposure. The result of this screening process is that either the facility being assessed poses no potential acute health risks (i.e., it “screens out”), or that it requires further, more refined

, assessment. The acute exposure scenario assumed w orst

- case meteorology (from on e year of local meteorology) and that a person is located downwind at the point of maximum impact during this same worst

- case 1

- hour period, but no nearer to the source than 100

meters.

Screening for potentially significant acute inhalation exposures also followed the HQ approach. We divided the maximum estimated acute exposure by each available short

- term threshold value to develop an array of HQ values relative to the various acute endpoints and thresholds. In general, when none of these HQ values are greater than one, there is low potential for acute risk. In those cases where HQ values above one are seen, additional information is used to determine if there is a potential for significant acute risks. Refined assessment for6

facilities in the Clay Cer amics source category included using aerial imagery of the facilit ies to
determine the maximum offsite 1

- hour concentrations.

Acid Gases Environmental Risk Screening In addition to potential health impacts, EPA evaluated the potential for environmental impacts when considering whether to exercise discretion under CAA Section 112(d)(4). 4 We applied the environmental risk screen methodology that is use d in the RTR Program under section 112 of the CAA to evaluate the potential for chronic exposure to HCl a nd HF emitted by Clay Ceramics facilities to cause phytotoxicity and reduced productivity of plants.

Although chlorine may also be emitted from Clay Ceramics facilities, chlorine gas is so reactive that it is not expected to remain in the environment ver y long after it is released. Chlorine immediately reacts with both organic and inorganic materials that it comes into contact with. Chlorine undergoes direct photolysis in the air and its half

- life in the troposphere is on the

order of several minutes. Th erefore, it is not considered in the environmental risk screening for

the Clay Ceramics source category.

The environmental screen uses air concentrations of HF and HCl from the HEM3 model used in the human health exposure and risk analysis. The HEM3 mode ling domain extends 50 km from the center of the facility. The defaults for HEM3 are to model 13 concentric rings at various distances (out to 50 km) from the facility with 16 concentration data points (one every 22.5 degrees) on each ring. Therefore, th ere are a total of 208 data points. All 16 data points on rings that we determine to be onsite are excluded from the 208 total. Therefore, the total number of data points included in the analysis generally varies depending on facility size. For the Clay

Ceramics source category, we used aerial imagery of the facilities to determine that 200 m is a typical facility radius, and we excluded data points inside this radius.

We derive d an area

- weighted average offsite annual ambient air concentration for HF and

HCl over the 50

- km modeling domain for each facility

. The area

- weighted average

concentrations wer e compared directly to the appropriate ecological benchmarks for each pollutant by dividing the area

- weighted average concentration by the appropriate ecological

benchmark. The result is called a hazard quotient (HQ). An HQ greater than one indicated that

the area

- weighted average concentration exceeded the ecological ben chmark.

Dose

- Response Information As discussed above, we assessed the pote ntial for health effects f rom 1

- hour and annual exposures, and the potential for environmental effects from annual modeled concentrations. The development and/ or use of health refe rence values and ecological values are discussed below.

Chronic Exposures

Dose

- response assessment for chronic exposure to acid gases w as based on existing recommendations for HAPs by the EPA Office of Air Quality Planning and Standards (OAQPS)

. 5 This in formation has been obtained from various sources and prioritized according

4 See Portland C ement NESHAP Final Rule , 75 FR 54970, 54986/3 (Sept 9, 2010).

5 US EPA, 2012. Table 1. Prioritized Chronic Dose

- Response Values (5/21/12). Office of Air Quality Planning and Standards. http://www.epa.gov/ttn/atw/toxsource/table1.pdf

.7

to (1) conceptual consistency with EPA risk assessment guidelines and (2) level of peer review received. The prioritization process was aimed at incorporating into our assessments the best available science with respect to dose

- response information. The recommendations are based on the following sources, in order of priority:

1) US Environmental Protection Agency (EPA). EPA has developed a dose

response assessment for chronic exposure to HCl. Th e dose

- response assessment for HCl provides a qualitative statement regarding the strength of scientific data and specifies an RfC to protect against effects other than cancer

. The RfC is defined as an “estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of

deleterious effect s during a lifetime.” The EPA disseminates dose

- response assessment information in several forms, based on the level of review. The Integrated Risk Information System (IRIS) 6 is an EPA database that contains scientific health assessment information,

incl uding dose

- response information. All IRIS assessments since 1996 have also undergone independent external peer review. The current IRIS process includes review by EPA scientists, interagency reviewers from other federal agencies, and the public, and peer review by independent scientists external to EPA. New IRIS values are developed and old IRIS values are updated as new health effects data become available. Refer to the “IRIS Track” website for detailed information on status and scheduling of current in dividual IRIS assessments and updates (http://cfpub.epa.gov/ncea/iristrac/index.cfm).

2) US Agency for Toxic Substances and Disease Registry (ATSDR). ATSDR, which is part of the US Department of Health and Human Services, develops and publishes

Minimum R isk Levels (MRLs) 7 for inhalation and oral exposure to many toxic substances

, including chlorine . As stated on the ATSDR web site: “Following discussions with scientists within the Department of Health and Human Services (HHS) and the EPA, ATSDR chose to adopt a practice similar to that of the EPA's Reference Dose (RfD) and Reference Concentration (RfC) for deriving substance specific health guidance levels for non neoplastic endpoints.” The MRL is defined as “an estimate of daily human exposure to a subs tance that is likely to be without an appreciable risk of adverse effects (other than cancer) over a specified duration of exposure.” ATSDR describes MRLs as substance

- specific estimates to be used by health

assessors to select environmental contaminants for further evaluation. Exposures above an MRL do not necessarily represent a threat, and MRLs are therefore not intended for use as predictors of adverse health effects or for setting cleanup levels.

3) California Environmental Protection Agency (CalEPA ). The CalEPA Office of Environmental Health Hazard Assessment has developed a dose

- response assessment for HF

for health effects other than cancer. The process for developing these assessments is similar to that used by EPA to develop IRIS values and in corporates significant external scientific peer review. As cited in the CalEPA Technical Support Document for developing their chronic assessments : “The guidelines for developing chronic inhalation exposure levels incorporate

6 US EPA, 2006. Integrated Risk Information System. http://www.epa.gov /iris/index.html.

7 US Agency for Toxic Substances and Disease Registry. 2006. Minimum Risk Levels (MRLs) for Hazardous Substances. http://www.atsdr.cdc.gov/mrls/index.html.8

many recommendations of the U.S. EPA 8 and NAS 9 .” The non

- cancer information includes available inhalation health risk guidance values expressed as chronic inhalation reference exposure levels (RELs) 10 . CalEPA defines the REL as “the concentration level at or below

which no health ef fects are anticipated in the general human population.”

The acid gases, their quantitative inhalation chronic non cancer dose

- response values, and the

source of each value are listed in Table 4.

Table 4. Dose

- Response Values for Chronic Inhalation Exposure to Acid Gases

Pollutant CAS Number 11 RfC (mg/m3) Source

Hydrochloric acid 7647010 0.02 IRIS Hydrofluoric acid 7664393 0.0 14 CAL

Chlorine 7782505 0.00 0 1 5 ATSDR

A cute Exposures

Dose

- response assessment for acute exposure to acid gases was also based on the existing recommendations of OAQPS for HAPs. 12 Depending on availability, the results from screening acute assessments are compared to both “no effects” reference levels for the general public, such as the California Reference Exposure Lev els (RELs), as well as emergency response levels, such as Acute Exposure Guideline Levels (AEGLs) and Emergency Response Planning Guidelines (ERPGs), with the recognition that the ultimate interpretation of any potential risks associated

with an estimated exceedance of a particular reference level depends on the definition of that level and any limitations expressed therein

.

California Acute Reference Exposure Levels (RELs). The California Environmental Protection Agency (CalEPA) has developed acute dose

- response reference values for many substances, expressing the results as acute inhalation Reference Exposure Levels (RELs). The acute REL (http://www.oehha.ca.gov/air/pdf/acuterel.pdf) is defined by CalEPA as “the

concentration level at or below which no adverse health effects are anticipated for a specified exposure duration. 13 RELs are based on the most sensitive, relevant, adverse health effect reported in the medical and toxicological literature. RELs are designed to protect the most

sensitive individ uals in the population by the inclusion of margins of safety. Since margins of safety are incorporated to address data gaps and uncertainties, exceeding the REL does not automatically indicate an adverse health impact.” Acute RELs are developed for 1

- hou r (and 8

-

8 US EPA, 1994. US Environmental Protection Agency. Methods for Derivation of I nhalation Reference Concentrations and Application of Inhalation Dosimetry. EPA/600/8

- 90/066F. Office of Research and Development. Washington, DC: U.S.EPA.

9 NRC, 1994. National Research Council. Science and Judgment in Risk Assessment. Washington, DC: Nat ional Academy Press.

10 CA Office of Environmental Health Hazard Assessment, 2005. Chronic Reference Exposure Levels Adopted by OEHHA as of December 2008. http://www.oehha.ca.gov/air/chronic_rels/AllChrels.html

. 11 Chemical Abstract Services identification number. For groups of compounds that lack a CAS number we have used a surrogate 3

- digit identifier corresponding to the group’s position on the CAA list of HAPs.

12 US EPA, 2011. Table 2. Acute Dose

- Response Values for Screening Risk Assessments (12/19/2 011). Office of Air Quality Planning and Standards. http://www.epa.gov/ttn/atw/toxsource/table2.pdf

. 13 CA Office of Environmental Health Hazard Assessment, 2000. All Acute Reference Exposure Levels developed by OEHHA as of May 2000. http://www.oehha.ca .gov/air/acute_rels/allAcRELs.html

.9

hour) exposures. The values incorporate uncertainty factors similar to those used in deriving EPA’s Inhalation Reference Concentrations (RfCs) for chronic exposures (and, in fact, California also has developed chronic RELs).

Acute Exposure Guidel ine Levels (AEGLs). AEGLs are developed by the National Advisory Committee (NAC) on Acute Exposure Guideline Levels (NAC/AEGL) for Hazardous Substances, and then reviewed and published by the National Research Council

. As described in

the Committee’s “St anding Operating Procedures (SOP)”, 14 AEGLs “represent threshold exposure limits for the general public and are applicable to emergency exposures ranging from 10 min to 8 h.” Their intended application is “for conducting risk assessments to aid in the

deve lopment of emergency preparedness and prevention plans, as well as real time emergency response actions, for accidental chemical releases at fixed facilities and from transport carriers.” The document states that “the primary purpose of the AEGL program a nd the NAC/AEGL Committee is to develop guideline levels for once

- in

- a

- lifetime, short

- term exposures to airborne concentrations of acutely toxic, high

- priority chemicals.” In detailing the intended application of AEGL values, the document states that, “I t is anticipated that the AEGL values will be used for regulatory and nonregulatory purposes by U.S. Federal and State agencies, and possibly the international community in conjunction with chemical emergency response, planning, and prevention programs. M ore specifically, the AEGL values will be used for conducting various risk assessments to aid in the development of emergency preparedness and prevention plans, as

well as real

- time emergency response actions, for accidental chemical releases at fixed faci lities and from transport carriers.”

The NAC/AEGL defines AEGL

- 1 and AEGL

- 2 as:

“AEGL

- 1 is the airborne concentration (expressed as ppm or mg/m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience notable discomfort, irritation, or certain asymptomatic nonsensory effects. However, the effects are not disabling and are transient and reversible upon cessation of exposure.”

“AEGL

- 2 is the airborne concentration (expressed as ppm or mg/m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience irreversible or other serious, long

- lasting adverse health effects or an impaired ability to escape.”

“Airborne concentrati ons below AEGL

- 1 represent exposure levels that can produce mild and progressively increasing but transient and nondisabling odor, taste, and sensory irritation or certain asymptomatic, nonsensory effects. With increasing airborne concentrations

above eac h AEGL, there is a progressive increase in the likelihood of occurrence and the severity of effects described for each corresponding AEGL. Although the AEGL values represent threshold levels for the general public, including susceptible subpopulations, su ch as infants, children, the elderly, persons with asthma, and those with other illnesses, it is recognized that individuals, subject to unique or idiosyncratic responses, could experience the effects described at concentrations below the corresponding AEG L.”

14 http://www.epa.gov/opptintr/aegl/pubs/sop.pdf

.10

Emergency Response Planning Guidelines (ERPGs). The American Industrial Hygiene Association (AIHA) has developed Emergency Response Planning Guidelines (ERPGs) 15 for acute exposures at three different levels of severity. These guidelines represent

co ncentrations for exposure of the general population (but not particularly sensitive persons) for up to 1 hour associated with effects expected to be mild or transient (ERPG

- 1), irreversible or serious (ERPG

- 2), and potentially life

- threatening (ERPG

- 3).

ERPG values 16 are described in their supporting documentation as follows: “Emergency Response Planning Guidelines (ERPGs) were developed for emergency planning and are intended as health based guideline concentrations for single exposures to chemicals. The se guidelines (i.e., the ERPG Documents and ERPG values) are intended for use as planning tools for assessing the adequacy of accident prevention and emergency response plans, including transportation emergency planning and for developing community emergen cy response plans. The emphasis is on ERPGs as planning values: When an actual chemical emergency occurs

there is seldom time to measure airborne concentrations and then to take action.”

ERPG

- 1 and ERPG

- 2 values are defined by AIHA as follows:

“ERPG

- 1 is the maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to 1 hour without experiencing other than mild transient adverse health effects or without perceiving a clearly defined, objectionable od or.”

“ERPG

- 2 is the maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to 1 hour without experiencing or developing irreversible or other serious health effects or symptoms which could impair an individual's ability to take protective action.”

The acid gases, their quantitative inhalation acute dose

- response values, and the source of each

value are listed in Table 5

.

Table 5. Dose

- Response Values for Acute Inhalation Exposure to Acid Gases

Pollutant CAS Number AEGL

- 1 (1

- hr) (mg/m 3 ) AEGL

- 2 (1

- hr) (mg/m 3 ) ERPG

- 1 (mg/m 3 ) ERPG

- 2 (mg/m 3 ) REL Hydrochloric acid 7647010 2.7 33 4.5 30 2.1
Hydrofluoric acid 7664393 0.82 20 1.6 16 0.24

Chlorine 7782505 1.5 5.8 2.9 8.7 0.21

E cological Risk Benchmarks for Acid Gases The environmental screening analysis evaluated potential damage and reduced productivity of plants due to chronic direct exposure to HCl and HF in the air. The chronic 90

- day benchmarks used in the environmental risk screen for t he acid gases are shown in Table 6 and discussed in the following section.

15 American Industrial Hygiene Association, 2011. Current AIHA ERPG Values. http://www.aiha.org/insideaiha/GuidelineDevelopment/ERPG/Documents/2011erpgweelhandbook_table

- only.pdf.

16 http://www.aiha.org/insideaiha/GuidelineDevelopment/ERPG/Pages/default.aspx

.11

Table 6. Acid Gas Benchmarks Included in the Environmental Risk Screen

a

- Note that the human health RfC is 20 μg/m3, which is lower than the ecological ben chmark.

Hydrogen Chloride

. For HCl, EPA identified chronic benchmark concentrations as

described in a 2009 EPA document on RTR risk assessment methodologies. 17 The chronic

benchmark for HCl was based on a LOEL from a short

- term exposure (20 minutes) that related HCl concentration to “changes” in the leaves of 7 out of 8 plant species as reported by Lerma n et
al. 18 It was the lowest exposure concentration at which effects of any type were seen (visible injury to some proportion of leaves). Haber’s law was used to extrapolate the 1.5 mg/m 3 LOEL

concentration ( 20

- minute exposure ) to a 0.5 mg/m 3 concentratio n expected to produce the same

effect after one hour. The 1

- hr estimated LOEL was extrapolated to a chronic benchmark by dividing by a factor of ten to yield 0.050 mg/m 3

, or 50 μg/m 3

.

Hydrogen Fluoride. For HF, EPA used two chronic benchmark concentrations for plants in the environmental screening analysis (Table 6)

. The value of 0.5 μg HF/m 3 is based on the Washington State criterion for gaseous HF

, and represents a LOEL . The value of 0.4 μg

HF/m 3 is based on the Environment Canada criteria and also represents a LOEL

.

To protect vegetation from adverse effects resulting from HF exposure, the Canadian

Council of Ministers of the Environment 19 recommends that HF concentrations not exceed 0.4 μg/m 3 ov er a 30

- to 90

- day period; HF concentrations can be higher for shorter exposures).

Environment Canada 20 defined the effect represented by the level of 0.4 μg HF/m 3 as :

"The level above which there are demonstrated effects on human health and/or the environment. It is scientifically based and defines the boundary between the LOAEL and the NOAEL. It is considered to be the level of exposure just below that most likely to

result in a defined and identifiable but minimal effect. The reference levels have no safety factors applied to them, as they are related directly to the LOAEL, and are the most

conservative estimates of the effect level."

17 US EPA, 2009. Risk and Technology Review (RTR) Risk Assessment Methodologies: For Review by the EPA’s Science Advisory Board with Case Studies

– MACT I Petroleum Refining Sources and Portland Cement Manufacturing. EPA

- 452/R

- 09

- 006. http://www.epa.gov/ttn/atw/rrisk/rtrpg.html.

18 Lerman, S., O.C. Taylor, and E.F. Darley, 1976. Phytotoxicity of Hydrogen Chloride Gas with a

Short

- Term Exposure. Atmospheric Environment, Vol.10, pp. 873

- 878.

19 CCME. 1999b. Canadian National Ambient Air Quality Objectives: Process and Status. In: Canadian Environmental Quality Guidelines, 1999, Canadian Council of Ministers of the Environment, Winnipeg. Publication No. 1299, IS BN 1

- 896997

- 34

- 1. Available at http://ceqg

- rcqe.ccme.ca/download/en/133/

. 20 EC. (Environment Canada). 1996. National Ambient Air Quality Objectives for Hydrogen Fluoride (HF). Science Assessment Document. A Report by the CEPA/FPAC Working Group on Air Qual ity Objectives and Guidelines. July. ISBN 0

- 662

- 25641

- 7, Catalogue En42

- 17/6

- 1997. Available online at: http://www.bape.gouv.qc.ca/sections/mandats/ap50_rio_tinto_alcan/documents/DQ3.1.1.pdf

. Acid Gas Chronic 90

- day Benchmark in μg/m 3

Hydrochloric acid

- NEL 50 a

Hydrofluoric acid

– Plant Community LOEL 0.5
Hydrofluoric acid

– Plant Community LOEL 0.412

H igh concentrations of HF in the air have also been linked to fluorosis in livestock. However, the HF concentratio ns at which fluorosis in livestock occur are higher than those at which plant damage begins. Therefore, the benchmarks for plants are protective of both plants

and livestock.

Results and Risk Characterization

Because the 600 tpy level of HCl

- equivalent em issions was determined such that no facility would exceed a TOSHI of one

, no facility in the individual acid gas model runs exceed ed

this level . Therefore, adverse chronic health effects are not likely to occur. However, because

the emissions equivalency was based on chronic dose

- response values, the 600 tpy level does not necessarily ensure that acute reference levels will not be exceed ed

. For the HCl and Cl 2 model runs, there were no facilities with acute screening HQ values exceeding one. For the HF model

run ( 420 tpy) , there were multiple facilities with screening HQ values (based on the REL) exceeding one, with the highest being an HQ of two

. There w ere no facilit ies with an acute screening HQ value based on the AEGL

- 1 that exceeded one. We review ed the cases where the HQ (REL) exceeded one by examining aerial imagery of the facilities to determine the maximum offsite HQ values. Table 8 gives the facilities with screening HQ (REL) values exceeding one, along with their screening HQ values and maxi mum offsite HQ values.

Table 8. Maximum Acute Screening and Offsite HQ (REL) Values for Clay Ceramics Facilities (based on 420 tons per year of HF).

Facility Maximum Acute Screening
HQ (REL) Value Maximum Offsite Acute HQ (REL) Value

01077NEI8517 2 2
40101NEIOK1015305 2 <1

45083NEI41474 2 2
47125NEITNRCC123 2 1

48049NEI13131 2 1

48113NEI12943 2 <1

48141NEI41683 <1 <1

55117NEIWI1179993 2 1

Although the maximum offsite acute HQ (REL) values for several facilities exceed one,

we conclude that there is low p otential for acute health effects for several reasons. First, the maximum offsite HQ (REL) value is only two

, and the maximum offsite HQ based on the

AEGL

- 1 is less than one . Also, the acute scenario is conservative in that it assume s t here is a person present at the location and time where the maximum HQ value occurs. Finally, it is unlikely that a facility would emit only HF, and emissions of the other acid gases did not result in HQ values exceeding one.

For HCl, t he environmental risk screen indicated that the area

- weighted average modeled

concentration of HCl around each facility (i.e., the area

- weighted average concentration of all offsite data points in the modeling domain) did not exceed the ecological benchmark

. In addition, the ecological benchmark was not exceeded at any offsite receptor location for any facility

. For HF, the environmental risk screen indicated that the area

- weighted average modeled concentration of HF around each facility did not exceed the ecological benchmar k. There were13

multiple facilities with modeled concentrations of HF at offsite receptor locations that exceeded the ecological benchmark, but the area over which the value was exceeded was no greater than one percent of the offsite modeling domain for eac h facility, indicating that there would not be any significant or widespread environmental effects.

In summary, we conclude that 600 tpy of HCl

- equivalent emissions per Clay Ceramics facility is unlikely to result in adverse chronic or acute human health effects at any facility in the
source category . The emissions level is s uch that the chronic health reference values are not

exceeded at any facility. A lthough the acute screening assessment indicates there are small

exceedances of the acute REL values at some facilities, we conclude that there is low potential for acute health effects because the maximum offsite HQ (REL) value is only two and the acute exposure scenario is conservative in that it assumes there is a person present at the location and

time where the maximum HQ value occurs . We also conclude that there is low potential for significant and widespread environmental effects. For HCl and HF, the environmental risk

screen indicated that the area

- weighted average modeled concentrations around each facility (i.e.,

the area

- weighted average concentration of all offsite data points in the modeling domain) did not exceed the ecological benchmark s

. In addition, the HCl benchmark was not exceeded anywhere offsite for any facility , and the area over which the HF benchmark w as exceeded was no greater than one percent of the offsite modeling domain for each facility in the category.