### 7/26/2010

To: Docket

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 Elasto mers Production Source Category and Table 3.5-2 Summary of Source Category Level Ri sk for Epichlorohydrin Elastomers 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). The MIR for cancer ha s 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 information received after the October proposal. The HI is now 0.1, down from the value of 0.2 at proposal. Th e 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 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 f acility (facility-wide) are presented in the attached “Source Category and Facility Wide Risk Results for Epichlorohydrin Elastomers Production” spreadsheet. The detailed risk modeling re sults for the facility-wide assessment is available in Appendix 6. We used the Nati onal Air Toxics Assessment (NATA) database for estimating facility-wide risks due to our lack of more recent facility-specific emissions data for some of the source categor ies 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 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 facilit y. We used the NATA for estimating facilitywide risks because we have just begun the residual risk reviews for source categories for

### the MACT standard and we have not yet gathered emissions da ta for many of the source categories. 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 hazard index (HI) of 0.5. The source category contributi on to the 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

0.003 epichlorohydrin (REL) epichlorohydrin (AEGL-1) ethylene oxide (ERGP-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. See Appendix A for more information.Source Category and Facility-WideRisk Results for EpichlorohydrinFacilityID FacilityName CityStateSourceCategoryMIR(in 1million)SourceCategoryResp_HIFacilityWide MIR(in 1million)FacilityWideMAX_HIFacilityWideHI_TYPEPercentSourceofCancerrisk isofFacilityWideriskEE1_NEI11153 ZEON CHEMICALS L P HATTIESBURGMS 10 0.1 10 0.5RespiratoryHI 100%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 Results