7/26/2010 

To: Docket 

From: Elaine Manning, Sector Based Assessment Group 

Subject: Post Proposal Revisions for Epichlorohydrin Elastomers Production Risk 

and Technology Assessment 

The attached minor revisions were made to the Epichlorohydrin Elastomers 

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 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. The most significant change from 

the October 10, 2008 proposal is the change in the maximum 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 information received after the 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 source category alone as presented in the 

attached Post-NPRM Source Category Level Risk table, additional analysis was 

performed to access the “facility-wide” risk. The results of the residual risk associated 

with all categories at the one facility (facility-wide) are presented in the attached “Source 

Category and Facility Wide Risk Results for Epichlorohydrin Elastomers Production”

spreadsheet. The detailed risk modeling results for the facility-wide assessment is 

available in Appendix 6. We used the National 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 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 time to estimate allowable facility-wide 

emissions. Thus, our facility-wide analysis is based solely on actual emissions. 

The maximum individual risk (MIR) and hazard index (HI) presented in the 

spreadsheet are based on emissions, as identified in the NATA database, from all 

emissions sources at the identified facility. 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 data 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 contribution 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 Epichlorohydrin Elastomers Production 

Source Category 

Prioritized Inhalation Dose-Response Value 

Identified by OAQPSa

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 Level 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) 10a

 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 Maximum 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 cancer risk for any epichlorohydrin elastomers facility was estimated as 30 in 1 million. However, the 

coordinates given for southwest corner of the area source (i.e., the fugitive emissions) are believed to be incorrect, so the results using those 

coordinates are not reported. The maximum risks presented in the table are those estimated using the best estimate of the emission point’s actual 

location. See Appendix A for more information.
Source Category and Facility-Wide Risk Results for Epichlorohydrin 

FacilityID FacilityName City 

S

t

a

t

e 

Source 

Category 

MIR 

(in 1 

million) 

Source 

Category

Resp_HI 

FacilityWide MIR 

(in 1 

million) 

FacilityWide MAX_HI

EE1_NEI11153 ZEON CHEMICALS L P HATTIESBURG 

MS 10 0.1 10 0.5

Notes: 1. NATA results (facility-wide) are from the final 2005 NATA analysis, dated May 2010 and based on the 2005 NATA NEI.  RTR results (source category only) are from RTR modeling conducted in June 2010 and based on June 2010 data. 

Attachments: Appendix 1 Revised Emissions Inventory Support Memorandum 

 Appendix 6 Detailed Risk Modeling Results