### 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 Ep ichlorohydrin Elastomers Production Risk and Technology Assessment

The attached minor revisions were made to the Epichlorohydrin Elastomers Production source category risk assessment wh ich was included in the proposal for the Group I Polymers and Resins; Marine Ve ssel Loading Operation; Mineral Wool Production; Pharmaceuticals Production; a nd Printing and Publishing Industry rulemaking issued on October 10, 2008. The updated Table 3.5-1 Summary of Emissions from the Epichlorohydrin Elastomers Production Source Category and Table 3.5-2 Summary of Source Category Level Risk for Epichlorohydrin Elastomers Production reflecting the minor changes are attached. Th e most significant change from the October 10, 2008 proposal is the change in the maximu m individual risk (MIR) and hazard index (HI). The MIR for cancer has gone down to 10 in a million from the previously proposed MIR of 30 in a million for the facility of concern, as a result of revised emissions coordinates information received after th e October proposal. The HI is now 0.1, down from the value of 0.2 at proposal. The attached Appendices 1 and 6 provide the supporting information for the changes.

The MACT-allowable emissions from this source category are estimated to be approximately the same as the modeled actual emissions; therefore, the 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 attached Appendix 6: “Detailed Risk Modeling Results”. We used the National Ai r Toxics 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 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 facility. The maximum facility-wide risks at the one facility with an operating epichlorohydrin elastomers process are estimated to be a cancer MIR of 10 in a million and a noncancer HI of 0.5. The source category contribution to th e facility-wide risk at this facility is 100% for the MIR and 20% for the HI.

### 3.5-1 Summary of Emissions from the Ep ichlorohydrin Elastomers Production Source Category

Prioritized Inhalation Dose-Response Value Identified by OAQPS a

HAP Emissions (tpy) Number of Facilities Reporting

HAP (1 facility in data set) Unit Risk Estimate for Cancer? Reference Concentration for Noncancer? Health Benchmark Value for Acute

Noncancer? PBHAP?

Toluene 44 1 Υ Υ Epichlorohydrin 0.4 1 Υ Υ Υ Ethylene Oxide 0.09 1 Υ Υ Υ

### Table 3-1. Summary of Source Category Leve l Risks for Epichlorohydrin Elastomers Production Facilities

Result HAP “Drivers” Facilities in Source Category Number of Major Source Facilities Estimated to be in Source Category 1 n/a

Number of Facilities Identified in NEI and Modeled in Risk Assessment 1 n/a

Cancer Risks Maximum Individual Lifetime Cancer Risk (in 1 million) 10 a ethylene oxide

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 ethylene oxide Greater than or equal to 1 in 1 million 1 ethylene oxide Chronic Noncancer Risks Maximum Respiratory Hazard Index 0.1 epichlorohydrin Number of Facilities with Maximu m Respiratory Hazard Index: Greater than 1 0 n/a Acute Noncancer Screening Results

Maximum Acute Hazard Quotient 0.2 0.01 0.03 epichlorohydrin (REL) epichlorohydrin (AEGL-1) toluene (ERPG-2) Number of Facilities With Potential for Acute Effects 0 n/a

Population Exposure Number of People Living Within 50 Kilometers of Facilities Modeled 218,000 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 90 n/a Greater than or equal to 1 in 1 million 800 n/a Number of People Exposed to Respiratory Hazard Index : Greater than 1 0 n/a Estimated Cancer Incidence (excess cancer cases per year) 0.0001 n/a

Contribution of HAP to Cancer Incidence ethylene oxide 98% n/a epichlorohydrin 2% n/a

Notes:

a The highest maximum individual lifetime can cer risk for any epichlorohydrin elastomers facility was estimated as 30 in 1 milli on. However, the coordinates given for southwest corner of the area source (i.e ., the fugitive emissions) are belie ved to be incorrect, so the r esults using those coordinates are not reported. The maximum risks presented in th e table are those estimated using the best estimate of the emis sion point’s actual location.

### Attachments: Appendix 1 Revised Em issions Inventory Support Memorandum Appendix 6 Detailed Risk Modeling Results