### 7/26/2010

To: Docket

From: Elaine Manning, Sect or Based Assessment Group

Subject: Post Proposal Revisions for Pol ybutadiene Rubber Production Risk and Technology Assessment

The attached minor revisions were made to the Polyutadiene Rubber Production source category risk assessment which was included in the proposal for the Group I Polymers and Resins; Marine Vessel Loading Operation; Mineral Wool Production; Pharmaceuticals Production; and Printing and P ublishing Industry rulemaking issued on October 10, 2008. The updated Table 3.6-1 Summary of Emissions from the Polybutadiene Rubber Production Source Category and Table 3.6-2 Summar y of Source Category Level Ri sk for Polybutadiene Rubber Production reflecting the minor ch anges are attached. The most significant change from the October 10, 2008 proposal is the change in the ma ximum individual risk (MIR) and hazard index (HI). Since the October 10, 2008 proposal we rece ived some updated emissions information for the polybutadiene rubber producti on facilities. Based on this new emissions information, the MIR for cancer has gone up to 30 in a million from the previously proposed MIR of 10 in a million. The HI is now 0.3, up from the value of 0.2 at proposal. The acute results also changed slightly. The attached Appendices 1, 6, and 7 provide the supporting information for the changes.

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

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

In addition to the risk presented by source ca tegory alone as presented in the attached Post-NPRM Source Category Level Risk table, a dditional analysis was performed to access the “facility-wide” risk. The results of the residual risk associated with al l categories at the one facility (facility-wide) are presented in the at tached “Source Category and Facility Wide Risk Results for Polybutadiene Rubber” spreadsheet. The detailed risk modeling results for the facility-wide assessment is available in A ppendix 6. We used the National Air Toxics Assessment (NATA) database for estimating facil ity-wide risks due to our lack of more recent facility-specific emissions data for some of the source categories included 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 ti me to estimate allowable facility-wide emissions. Thus, our facility-wide analysis is based solely on actual emissions.

The maximum individual risk (MIR) and hazar d index (HI) presented in the spreadsheet are based on emissions, as identified in the NAT A database, from all emissions sources at the identified facility. The facility with the ma ximum facility-wide risks is estimated to have a

cancer MIR of 30 in a million and an HI of 0.3. The source categor y contribution to the facilitywide risk at this facility is 100% for both the MIR and the HI.

### Table 3.6-1 Summary of Emissions from th e Polybutadiene Rubber Production Source Category

Prioritized Inhalation Dose -Response Value Identified by OAQPS

HAP a Emissions (tpy) Number
of
Facilities Reporting

HAP (5
facilities
in data

set) Unit Risk
Estimate for

Cancer? Reference
Concentration for
Noncancer? Health Benchmark
Values for Acute
Noncancer? PBHAP?

Hexane 1,584 4 Υ Υ

Toluene 510 2 Υ Υ
1,3-Butadiene 74 5 Υ Υ Υ
Styrene 68 5 Υ Υ
Ethyl Benzene 23 1 Υ

Chlorobenzene 2 1 Υ Υ

Methanol 0.07 1 Υ Υ

Nickel 0.0007 1 Υ Υ Υ

### Table 3.6-2 Summary of Source Category Level Risks for Polybutadiene Rubber Facilities

Result HAP “Drivers” Facilities in Source Category Number of Major Source Facilities Estimated to be in Source Category 5 n/a

Number of Facilities Identified in NEI and

Modeled in Risk Assessment 5 n/a

Cancer Risks Maximum Individual Lifetime Cancer Risk (in 1 million) 30 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 2 1,3-butadiene Greater than or equal to 1 in 1 million 4 1,3-butadiene

Chronic Noncancer Risks Maximum Reproductive Hazard Index 0.3 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 12

0.6

0.2 toluene (REL) toluene (AEGL-1) toluene (ERPG-2)

Number of Facilities With Potential for Acute

Effects 1 toluene (REL)

Acute Noncancer Refined Results Maximum Acute Hazard Quotient 1 toluene

Number of Facilities With Potential for Acute

Effects 0

Population Exposure Number of People Living Within 50 Kilometers

of Facilities Modeled 1,700,000 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 20 n/a Greater than or equal to 1 in 1 million 24,000 n/a Number of People Exposed to Reproductive Hazard Index : Greater than 1 0 n/a Estimated Cancer Incidence (excess cancer cases per year) 0.003 n/a

Contribution of HAP to Cancer Incidence 1,3-butadiene 98% n/a ethyl benzene 2% n/aSource Category and Facility-Wide Risk Results for Polybutadiene Rubber ProductionFacilityID FacilityName City StateSourceCategoryMIR(in 1million)SourceCategoryRepro_HIFacilityWide MIR(in 1million)FacilityWideMAX_HIFacility-WideHI_TYPEPercentSourcerisk is ofFacilityWide riskPB1_NEI7446LANXESSCORPORATIONORANGE TX 30 0.3 30 0.3ReproductiveHI102%PB1_NEI7039GOODYEAR TIRE &RUBBER BEAUMONTCHEMICAL PLANT BEAUMONT TX 10 0.2 10 0.2ReproductiveHI100%PB1_NEI32876AMERICAN SYNTHETICRUBBERLOUISVILLE KY 3 0.05 3 0.05ReproductiveHI98%PB1_NEI8307 Firestone ORANGE TX 9 0.2 10 0.2ReproductiveHI93%PB1_NEI33012FIRESTONEPOLYMERS/LAKECHARLES FACILITYSULPHUR LA 1 0.009 2 0.04RespiratoryHI26%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.Attachments: Appendix 1 Revised Emissions InventorySupport MemorandumAppendix 6 Detailed Risk Modeling ResultsAppendix 7 Acute Impacts Refined Analysis Figures