9/13/2010 

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

From: Elaine Manning, Sector Based Assessment Group 

Subject: Post Proposal Revisions for Marine Tank Vessel Loading Facilities Risk 

and Technology Assessment 

The attached revisions were made to the Marine Tank Vessel Loading Operations 

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 3.3-1 Summary of Emissions from the Marine 

Tank Vessel Loading Operations Source Category, Table 3.3-2 Summary of Source 

Category Level Risk for Marine Tank Vessel Loading Operations, and Table 3.3-3 

Summary of Acute Refined Results for Marine Tank Vessel Loading Operations 

reflecting the changes are attached. The most significant change from the October 10, 

2008 proposal is the change in the maximum individual risk (MIR). Based on updated 

emission information obtained since the October 2008 proposal the risk results changed 

for the MIR and hazard index (HI). The maximum MIR for cancer changed from 1 at 

proposal to 20 for the current analysis. The maximum HI changed from 0.006 at 

proposal to 0.3 for the current analysis. The screening acute value of 5 for glycol ethers 

reduced to below 1 after the refined acute analysis was done. The next facility with an 

acute value of 3 for benzene became 0.96 (rounded to 1) with the refined analysis. The 

attached Appendices 1 and 6 provide the supporting information for the changes. 

We used a scaling factor of 3 to adjust for allowable emissions. Based on the 

scaling factor, the MIR based on MACT-allowable emissions is estimated to be 60-in-1-

million, and the maximum HI value is 0.9. 

 

In addition to the risk presented by the source category alone as shown in the 

attached Summary of 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 known facilities (facility-wide) are presented in the attached 

Appendix 6 “Detailed Risk Modeling Results “. 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 facility-wide MIR and HI available in Appendix 6 are based on emissions, as 

identified in the NATA, from all emissions sources at the identified facilities. The 
maximum facility-wide risks are estimated to be a cancer MIR of 200 in a million and a 

noncancer HI of 4, which occur at different facilities. The source category contribution 

to facilities with a 200 in a million risk is small at 10% (for both facilities) with a source 

category MIR cancer risk of 20 in a million. The maximum source category noncancer 

HI is 0.3 for reproductive and the maximum facility-wide HI is 4 for respiratory 

(maximum source category and facility-wide HI values occur at different facilities). The 

facility with the maximum facility-wide HI of 4 (respiratory) has a source contribution 

less than 1%. 
Table 3.3-1 Summary of Emissions from the Marine Tank Vessel Loading 

Operations Source Category 

Prioritized Inhalation Dose-Response Value 

Identified by OAQPSb

HAPa Emissions 

(tpy) 

Number of 

Facilities 

Reporting HAP 

(152 facilities in 

data set) 

Unit Risk 

Estimate for 

Cancer? 

Reference 

Concentration 

for Chronic 

Noncancer? 

Health 

Benchmark 

Values for Acute 

Noncancer? 

PBHAP? 

Hexane 87 104 Υ Υ 

Methyl Tert-Butyl Ether 62 12 Υ Υ Υ 

Toluene 46 111 Υ Υ 

Methanol 48 25 Υ Υ 

Benzene6 42 105 Υ Υ Υ 

Xylenes (Mixture of o, m, 

and p Isomers) 31 102 Υ Υ 

1,3-Butadiene 27 5 Υ Υ Υ

Styrene 23 27 Υ Υ 

Cumene 10 28 Υ Υ 

Ethylene Dichloride 6 8 Υ Υ Υ 

Naphthalene 8 20 Υ Υ

Ethyl Benzene 5 47 Υ Υ 

Trichloroethylene 3 4 Υ Υ Υ 

Acrylonitrile 2 7 Υ Υ Υ 

Tetrachloroethylene 2 8 Υ Υ Υ 

Propylene Oxide 2 3 Υ Υ Υ

Vinyl Acetate 2 7 Υ Υ

Acetaldehyde 1 2 Υ Υ Υ

Chloroform 1 2 Υ Υ

Glycol Ethers 0.5 3 Υ Υ

2,2,4-Trimethylpentane 0.4 12 

Methylene Chloride 0.4 1 Υ Υ Υ

Methyl Methacrylate 0.3 3 Υ Υ

Biphenyl 0.2 12 Υ

m-Xylene 0.2 2 Υ Υ

Phenol 0.2 16 Υ Υ

Aniline 0.2 2 Υ Υ Υ

Methyl Isobutyl Ketone 0.2 2 Υ

Ethylene Glycol 0.1 21 Υ

o-Xylene 0.09 2 Υ Υ

Ethyl Acrylate 0.08 2 Υ

2-Nitropropane 0.08 2 Υ Υ

Acrylic Acid 0.06 3 Υ Υ

Vinyl Chloride 0.04 1 Υ Υ Υ

1-Chloro-2,3-Epoxypropane 0.02 1 Υ Υ Υ

1,2-Epoxybutane 0.02 1 Υ

Carbon Tetrachloride 0.02 1 Υ Υ Υ
Prioritized Inhalation Dose-Response Value 

Identified by OAQPSb

HAPa Emissions 

(tpy) 

Number of 

Facilities 

Reporting HAP 

(152 facilities in 

data set) 

Unit Risk 

Estimate for 

Cancer? 

Reference 

Concentration 

for Chronic 

Noncancer? 

Health 

Benchmark 

Values for Acute 

Noncancer? 

PBHAP? 

Cellosolve Solvent 0.01 1 Υ Υ

Ethylene Glycol Monoethyl 

Ether 0.007 1 Υ Υ

Cresols (mixed) 0.005 12 Υ

Dimethyl Formamide 0.006 1 Υ Υ

Formaldehyde 0.003 1 Υ Υ Υ

Chlorobenzene 0.002 1 Υ Υ

Hydrochloric Acid 0.001 1 Υ Υ

Diethanolamine 0.001 1 Υ

Methylene Diphenyl 

Diisocyanate 0.001 1 Υ Υ

Propylene Dichloride 0.0006 1 Υ Υ

1,2,4-Trichlorobenzene 0.0006 1 Υ

Chlorine 0.0005 1 Υ Υ

Diethylene Glycol 

Monoethyl Ether 0.0005 1 Υ

o-Cresol 0.0005 1 Υ

POM 71002 0.0002 2 Υ

p-Xylene 0.0001 1 Υ Υ

Manganese & Compounds 0.00006 1 Υ

Lead & Compounds 0.00002 1 Υ Υ

Chromium 0.00001 1 Υ

Nickel 

0.00000

9 1 Υ Υ

Arsenic 

0.00000

6 1 Υ Υ

Cadmium Compounds 

0.00000

3 1 Υ Υ

Mercury Compounds 

0.00000

3 1 Υ Υ

Selenium Compounds 

0.00000

2 1 Υ

Beryllium Compounds 

0.00000

1 1 Υ Υ Υ
Table 3.3-2. Summary of Source Category Level Risks for Marine Tank Vessel Loading 

Operations

Result HAP “Drivers” 

Facilities in Source Category 

Number of Major Source Facilities Estimated to 

be in Source Category 300 n/a 

Number of Facilities Identified in NEI and 

Modeled in post-NPRM Risk Assessment 152 n/a 

Cancer Risks 

Maximum Individual Lifetime Cancer Risk (in 1 

million) 20 benzene 

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 3 benzene, 1,3-butadiene, naphthalene 

 Greater than or equal to 1 in 1 million 3 benzene, 1,3-butadiene, naphthalene 

Chronic Noncancer Risks 

Maximum Reproductive Hazard Index 0.3 1,3-butadiene 

Number of Facilities with Maximum Reproductive Hazard Index: 

 Greater than 1 0 n/a 

Acute Noncancer Screening Results

Maximum Acute Hazard Quotient 5 glycol ethers (REL) 

Number of Facilities With Potential for Acute 

Effects 2 glycol ethers, benzene 

Acute Noncancer Refined Results

Maximum Acute Hazard Quotient 1 benzene (REL) 

Number of Facilities With Potential for Acute 

Effects 0 

Population Exposure 

Number of People Living Within 50 Kilometers 

of Facilities Modeled 61,000,000 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 1,000 n/a 

 Greater than or equal to 1 in 1 million 71,000 n/a 

Number of People Exposed to Reproductive Hazard Index: 

 Greater than 1 0 n/a 

Estimated Cancer Incidence (excess cancer cases 

per year) 0.01 n/a 

Contribution of HAP to Cancer Incidence 

 1,3-butadiene 59% n/a 

 benzene 21% n/a 

 naphthalene 14% n/a 

 acrylonitrile 4% n/a 

 ethylene dichloride 2% 
Attachments: Appendix 1 Revised Emissions Inventory Support Memorandum 

 Appendix 6 Detailed Risk Modeling Results 

 Appendix 7 Acute Impacts Refined Analysis Figure