### 7/26/2010

To: Docket

From: Elaine Manning, Sect or Based Assessment Group

Subject: Post Proposal Revisions for Styren e Butadiene Rubber Facilities Risk and Technology Assessment

The attached minor revisions were made to the Styrene Butadiene Rubber source category risk assessment which was included in the proposal for the Group I Polymers and Resins; Marine Vessel Loading Op eration; Mineral Wool Production; Pharmaceuticals Production; and Printing and Publishing Industry rulemaking issued on October 10, 2008. The updated Table 3.7-1 Su mmary of Emissions from the Styrene Butadiene and Latex Production Source Catego ry and Table 3.7-2 Summary of Source Category Level Risk for Polymers & Resins I - Styrene Butadiene Rubber and Latex Production reflecting the minor ch anges are attached. The mo st significant change from the October 10, 2008 proposal is the change in the maximum individu al risk (MIR) and hazard index (HI). Since th e October 10, 2008 proposal several styrene butadiene rubber production facilities have stopped produc tion and we received updated emissions

information. Based on the facilities left in this source category and using the updated emissions information, the MIR for cancer has gone up to 10 in a million from the previously proposed MIR of 7 in a million. The HI is now 0.2, up from the value of 0.1 at proposal. The acute results remain the same. The attached Appendices 1, 6, and 7 provide the supporting inform ation for the changes.

The MACT-allowable emissions of the compound ( 1,3-butadiene) 

### driving the risk from this source category is estimated to be approximately the same as the modeled actual emissions; therefore, th e risks results are equal.

In addition to the risk presented by sour ce category alone as presented in the attached Post-NPRM Source Category Leve l Risk table, additional analysis was performed to access the “facility-w ide” risk. The results of the residual risk associated with all categories at the one facility (facil ity-wide) are presented in the attached “Source Category and Facility Wide Risk Results for Styrene Butadiene Rubber” spreadsheet. The detailed risk modeling results for the facility-wide assessment is available in Appendix 6. We used the National Air T oxics Assessment (NATA) database for estimating facility-wide risks due to our lack of more recen t facility-specific emissions data for some of the source categories in cluded in the facility-wide analyses. Additionally, because we have not yet begun our thorough residual risk review for most source categories, we are unable at this time to estimate allowable facility-wide emissions. Thus, our facility-wide analysis is based solely on actual emissions.

The maximum individual risk (MIR) a nd hazard index (HI) presented in the spreadsheet are based on emissions, as id entified in the NATA database, from all

### emissions sources at the identified facility. The facility with the maximum facility-wide

risks is estimated to have a cancer MIR of 70 in a million and an HI of 1. The source category contribution to th e facility-wide risk at this facility is about 5% for the MIR and

10% for the HI.

### Table 3.7-1 Summary of Emissions from the Styrene – Butadiene and Latex Production Source Category

Prioritized Inhalation Dose-Response Value Identified by OAQPS

HAP Emissions (tpy) Number of

Facilities Reporting HAP

(6 facilities in data set) Unit Risk

Estimate for

Cancer? Reference

Concentration

for Noncancer? Health

Benchmark

Values for Acute

Noncancer? PBHAP?

Styrene 275 6 Υ Υ

1,3-Butadiene 14 6 Υ Υ Υ
Ethyl Benzene 4 4 Υ Xylenes (Mixture of o, m, and p Isomers) 4 2 Υ Υ

Carbon Disulfide 3 1 Υ Υ
Acrylic Acid 0.8 3 Υ Υ

Toluene 0.7 2 Υ Υ

Benzene 6 0.7 1 Υ Υ Υ

Methanol 0.6 1 Υ Υ
Acrylonitrile 0.1 1 Υ Υ Υ
Vinylidene Chloride 0.05 1 Υ
Hydrochloric Acid 0.04 1 Υ Υ
Ethyl Acrylate 0.04 1 Υ
Methyl Methacrylate 0 1 Υ Υ

### Table 3.7-2 Summary of Source Category Level Risks for Polymers & Resins I - Styrene

Butadiene Rubber and Latex Facilities

Result HAP “Drivers”
Facilities in Source Category Number of Major Source Facilities Estimated to be in Source Category 6 n/a

Number of Facilities Identified in NEI and

Modeled in Risk Assessment 6 n/a

Cancer Risks Maximum Individual Lifetime Cancer Risk (in 1 million) 10 1,3-butadiene

Number of Facilities with Maximum Individual Lifetime Cancer Risk: Greater than or equal to 100 in 1 million 0 n/a Greater than or equal to 10 in 1 million 1 1,3-butadiene Greater than or equal to 1 in 1 million 4 1,3-butadiene, acrylonitrile

Chronic Noncancer Risks Maximum Reproductive Hazard Index 0.2 1,3-butadiene Number of Facilities with Maximu m Reproductive Hazard Index:

Greater than 1 0 n/a Acute Noncancer Screening Results

Maximum Acute Hazard Quotient 2

0.6

0.09 styrene (REL) styrene (AEGL-1) styrene (AEGL-2)

Number of Facilities With Potential for Acute

Effects 1 styrene

Acute Noncancer Refined Results Maximum Acute Hazard Quotient 0.4 styrene (REL)

Number of Facilities With Potential for Acute

Effects 0

Population Exposure Number of People Living Within 50 Kilometers

of Facilities Modeled 6,700,000 n/a

Number of People Exposed to Cancer Risk: Greater than or equal to 100 in 1 million 0 n/a Greater than or equal to 10 in 1 million 3 n/a Greater than or equal to 1 in 1 million 25,000 n/a Number of People Exposed to Reproductive Hazard Index : Greater than 1 0 n/a Estimated Cancer Incidence (excess cancer cases per year) 0.004 n/a

Contribution of HAP to Cancer Incidence
1,3-butadiene 98% n/a ethyl benzene 1% n/aSource Category and Facility-Wide Risk Results for Styrene Butadiene Rubber ProductionFacilityID FacilityName City StateSourceCategoryMIR(in 1million)SourceCategoryRepro_HIFacilityWide MIR(in 1million)FacilityWideMAX_HIFacility-WideHI_TYPEPercentSourcerisk is ofFacilityWide riskSB1_NEI8108DOW CHEMICAL CO.DALTON PLANTDALTON GA 0.2 0.004 0.2 0.003ReproductiveHI145%2SB1_NEI13230GOODYEAR HOUSTONCHEM PLT HOUSTON TX 7 0.1 10 1RespiratoryHI73%SB1_NEI43289DOW NORTH AMERICAALLYN'S POINT PLANTGALESFERRY CT 0.8 0.01 1 0.08RespiratoryHI70%SB1_NEI8360AMERIPOL SYNPOLCORP.PORTNECHES TX 10 0.2 20 0.3ReproductiveHI48%SB1_NEI11906THE DOW CHEMICALCOMPANY U.S.A.,MIDLANDMIDLAND MI 2 0.03 40 0.8RespiratoryHI5%SB1_NEI33015LIONCOPOLYMER/BATONROUGE PLANTBATONROUGE LA 3 0.06 70 1ReproductiveHI5%Notes:1. NATA results (facility wide) are from the final2005 NATA analysis, dated May 2010 and based on the 2005 NATA NEI.RTR results (source category only) are fromRTR modeling conducted in June 2010 and based on June 2010 data.2. The percent source risk of facility wide risk for Dow Chemical, Dalton, GA is based upon theraw MIR values which are not rounded to 1 significant figure.Attachments: Appendix 1 Revised Emissions InventorySupport MemorandumAppendix 6 Detailed Risk Modeling Results