### 9/13/2010

To: Docket – ID No. EPA-HQ-OAR-2010-0600

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 Source Category Level Risk table, additional analysis was performed to access the “facility-wide” risk. The resu lts of the residual risk asso ciated with all categories at the one facility (facility-wide) are presented in the attach ed Appendix 6. We used the National Air Toxics Assessment (NATA) databa se for estimating facility-wide risks due
to our lack of more recent facility-specific emissions data for some of the source categories included in the fac ility-wide analyses. Additiona lly, 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 emi ssions. Thus, our facility-wide analysis is based solely on actual emissions.

The facility-wide MIR and HI available in Appendix 6 are based on emissions, as identified in the NATA database, from all emi ssions sources at the identified facilities. The facility with the maximum facility-wide ri sks is estimated to have a cancer MIR of
70 in a million and an HI of 1. The source cate gory contribution to the facility-wide risk

### at this facility is about 5% for the MIR and 10% for the HI. The facility with the next highest MIR is 40 in a million with an HI of 1. The source categor y contribution to the facility wide MIR is 5% 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/a

### Attachments: Appendix 1 Revised Em issions Inventory Support Memorandum Appendix 6 Detailed Risk Modeling Results Appendix 7 Acute Impacts Refined Analysis Figures