risks associated with point source emissions of n … · risks associated with point source...

Health Sciences

Risks Associated with Point

Source Emissions of n-Propyl

Bromide

QMS QA ID no. 1204300.000 A0T0 1012 RR01

Risks Associated with Point

Source Emissions of n-Propyl

Bromide

Prepared for

Halogenated Solvents Industry Alliance, Inc.

1530 Wilson Blvd., Suite 690

Arlington, VA 22209

Prepared by

Exponent

1800 Diagonal Road, Suite 500

Alexandria, VA 22314

November 29, 2012

Exponent, Inc.

QMS QA ID no. 1204300.000 A0T0 1012 RR01 ii

Contents

Page

List of Figures iii

List of Tables iv

Executive Summary v

Introduction 1

Estimation of Unit Risk Factor 3

Emissions Estimates 5

Degreasing 5

Spray Adhesive Use 5

Fabrication Company A 5

Fabrication Company B 8

Dry Cleaning 10

Summary 10

Estimation of Air Concentrations and Cancer Risk 12

Degreasing Operation 12

Fabrication Company A 14

Fabrication Company B 16

Virginia Dry Cleaner 19

Massachusetts Dry Cleaner 21

Summary 23

Conclusions 24

References 25

QMS QA ID no. 1204300.000 A0T0 1012 RR01 iii

List of Figures

Page

Figure 1. Multistage cancer model fit for alveolar/bronchiolar neoplasms (output from

EPA’s BMDS software program) 4

Figure 2. Google Earth view of the Collegeville, Pennsylvania facility with a degreasing

use of nPB. Stacks are shown on building ceiling and census tract centroids

with black and white dots. 13

Figure 3. Google Earth view of Fabrication Company A in Thomasville, North

Carolina. Building is shown to the right of the Regency International Blvd

street label and census tract centroids with black and white dots. 15

Figure 4. Google Earth view of Fabrication Company B in Mooresville, North Carolina.

Building is in center of page just south of Highway 152 and census tract

centroids are labeled with black and white dots. 17

Figure 5. Google Earth view of a dry cleaner on North Quaker Lane (Highway 402) in

Alexandria, VA. Building is in center of the page and census tract centroids

are labeled with black and white dots. 19

Figure 6. Google Earth view of a dry cleaner on Main Street in Waltham,

Massachusetts. Building is in center of the page and census tract centroids

are labeled with black and white dots. 21

QMS QA ID no. 1204300.000 A0T0 1012 RR01 iv

List of Tables

Page

Table 1. Emissions estimates for Fabrication Company A 7

Table 2. Emissions estimates for Fabrication Company B 9

Table 3. Summary of nPB emission estimates from different facilities 10

Table 4. Summary of lifetime cancer risk estimates in census tracts for degreasing

operation 14

Table 5. Summary of lifetime cancer risk estimates for polar grid for degreasing

operation 14

Table 6. Summary of lifetime cancer risk estimates in census tracts for Fabrication

Company A 16

Table 7. Summary of lifetime cancer risk estimates for polar grid for Fabrication

Company A 16

Table 8. Summary of lifetime cancer risk estimates in census tracts for Fabrication

Company B 18

Table 9. Summary of lifetime cancer risk estimates for polar grid for Fabrication

Company B 18

Table 10. Summary of lifetime cancer risk estimates in census tracts for Virginia dry

cleaner 20

Table 11. Summary of lifetime cancer risk estimates for polar grid for Virginia dry

cleaner 20

Table 12. Summary of lifetime cancer risk estimates in census tracts for Massachusetts

dry cleaner 22

Table 13. Summary of lifetime cancer risk estimates for polar grid for Massachusetts

dry cleaner 22

Table 14. Maximum estimated nPB cancer risks for each facility by census tract and

polar grid 23

QMS QA ID no. 1204300.000 A0T0 1012 RR01 v

Executive Summary

This report analyzes potential risks to populations living near facilities that use n-propyl

bromide (nPB). nPB is a solvent that has been introduced as an unregulated replacement for

chlorinated solvents. It is marketed as “non-hazardous,” but there have been a number of case

reports of reproductive and neurotoxic effects in exposed workers. Moreover, the National

Toxicology Program (NTP) recently concluded that nPB is carcinogenic based on 2-year rodent

bioassays. Chemicals that are carcinogenic may be regulated as hazardous air pollutants

(HAPs) under the Clean Air Act if the resulting population exposure exceeds a 1 in 1 million

lifetime cancer risk.

Section 112(b)(2) of the Clean Air Act requires the U.S. Environmental Protection

Agency (EPA) to make periodic revisions to the initial list of HAPs in § 112(b)(1), outlines the

criteria to be applied in deciding whether to add a substance to the list, and identifies pollutants

that should be listed as those “which present, or may present, through inhalation or other routes

of exposure, a threat of adverse human health effects (including, but not limited to, substances

which are known to be, or may reasonably be anticipated to be, carcinogenic, mutagenic,

teratogenic, neurotoxic, which cause reproductive dysfunction, or which are acutely or

chronically toxic).” Using accepted EPA methodologies, this report characterizes potential

human exposures and estimates lifetime potential cancer risks for populations downwind of

nPB-using facilities, in support of a petition to list nPB as an HAP submitted on October 28,

2010 by the Halogenated Solvents Industry Alliance, Inc.

The steps in the analysis were: (1) estimation of the unit cancer risk based on the NTP

bioassays, (2) estimation of emissions from facilities that use nPB, and (3) estimation of

downwind air concentrations and population cancer risk using EPA’s HEM-3 model.

The unit cancer risk was estimated with EPA’s BMDS software for benchmark dose

analysis. The largest tumor counts for nPB were for alveolar/bronchiolar neoplasms in female

mice with counts of 1/50, 9/50, 8/50, and 14/50 for the 0, 125, 250, and 500 ppm exposure

groups, respectively. After adjusting for the exposure duration in the bioassay (6 hours per day,

5 days per week) to lifetime exposure, the resulting unit risk factor was 2.1×10-6

per µg/m3.

The emissions of nPB are not straightforward to estimate because it is not regulated as a

HAP. Therefore, facilities are not required to report their emissions to EPA. We used the

following means to estimate nPB emissions:

A narrow tube manufacturing facility in Collegeville, Pennsylvania switched from

using TCE to using nPB in its degreasing operations around 2008. The facility was

QMS QA ID no. 1204300.000 A0T0 1012 RR01 vi

required to report HAP/TCE emissions to the state of Pennsylvania and those

emissions dropped from 35/34 tons per year in 2007 to 5/4 in 2008 to none in 2009

and 2010. Volatile organic compound (VOC) emissions for 2007-10 went from 47

to 40 to 34 to 46 tons per year. As nPB is a VOC, it is assumed that nPB emissions

after the switch from TCE accounted for the VOC emissions in 2008-10, estimated

conservatively at 35 tons per year, comparable to the TCE emissions before the

switch.

Two furniture manufacturing facilities in North Carolina use nPB as a spray

adhesive. The National Institute of Occupational Safety & Health (NIOSH)

investigated complaints of potential health effects from nPB use for the workers at

the facilities and made site visits (NIOSH, 2002a,b). From the industrial hygiene

measurements made at the facilities, the emissions were estimated. The resulting

estimates were 2.8 tons per year (Fabrication Company A) and 18 tons per year

(Fabrication Company B).

Blando et al. (2010) measured nPB exposures in several New Jersey dry cleaners. In

a personal communication, Dr. Blando indicated that the dry cleaners use about 5

gallons of nPB every few days, which corresponds to about 2.6 tons per year

assuming 250 days per year of use. This estimate was identical to a permit

allowance issued to a dry cleaner in Ohio.

The degreasing operation facility and the furniture manufacturing facilities were

identified in Google Earth and the dimensions of the buildings were estimated. Two dry

cleaners were identified in Virginia and Massachusetts and the dimensions of the buildings were

estimated in Google Earth. We do not have particular information that these dry cleaners use

nPB but use them to simulate the potential risk from those facilities if they did use nPB.

The building dimension estimates, emission estimates, and assumptions about the release

points were entered into HEM-3. The model was run using default conditions for each of the

facilities. The model provides concentration estimates for the centroid of nearby census tracts

and for a polar grid with rings ranging from 100 meters to 50,000 meters.

The HEM-3 results showed that 4 of the 5 facilities had lifetime cancer risks of greater

than 1 in 1 million in a nearby census tract. All of the facilities had nearby locations on the

polar grid with lifetime cancer risks greater than 1 in 1 million, and three of the facilities had

nearby locations on the polar grid with lifetime cancer risks greater than 10 in a million. Only

five facilities were modeled in this report, but there are a large number of potential facilities that

could use nPB. Higher risks are possible if there are other facilities that have higher emissions

QMS QA ID no. 1204300.000 A0T0 1012 RR01 vii

than assumed for the facilities modeled in this report or have populations that are closer to the

facility.

These results show that the lifetime cancer risks to populations living near facilities that

use nPB are greater than the threshold for regulation of sources of carcinogens under the Clean

Air Act. See Clean Air Act § 112(f)(2): “If standards promulgated pursuant to subsection (d) of

this section and applicable to a category or subcategory of sources emitting a pollutant (or

pollutants) classified as a known, probable, or possible human carcinogen do not reduce lifetime

excess cancer risks to the individual most exposed to emissions in a category or subcategory to

less than one in one million, the Administrator shall promulgate standards under this subsection

for such source category.”

This report makes a number of assumptions, particularly with regard to facility

emissions. The emission estimates were made without access to the facility, specific use data

provided by the facility, or stack testing data, so it is conceivable that the actual emissions of the

facilities could be different. However, the report provides a range of scenarios that are plausible

representations of facilities that may use or could use nPB. Thus, the estimates provide a basis

for characterizing the potential lifetime cancer risks associated with populations living near

facilities using nPB.

QMS QA ID no. 1204300.000 A0T0 1012 RR01 1

Introduction

This report provides estimates of the potential cancer risk for populations surrounding

facilities using n-propyl bromide (nPB). nPB is a solvent that, in recent years, has found

applications in industry for degreasing and foam fabrication, where it is used as a solvent-based

adhesive. It has also been used for dry cleaning. It is generally marketed as a replacement for

chlorinated solvents.

Unlike chlorinated solvents, nPB is not regulated as a HAP under the Clean Air Act.

Thus, emissions of nPB are not required to be reported to EPA. As a result, some manufacturers

of nPB market it as being “environmentally friendly” or “non-hazardous.” For example,

DrySolv, an nPB product for dry cleaning, is marketed as being “non-chlorinated, non-

flammable, non-hazardous, and is vastly more environmentally responsible than PERC.” 1

nPB has been evaluated for carcinogenicity by the National Toxicology Program (NTP,

2011). Despite being described by some as “non-hazardous,” NTP found “clear evidence of

carcinogenic activity” for two tumor types and some evidence of carcinogenic activity for a

third tumor type.

Section 112 of the Clean Air Act addresses the listing of HAPs as follows:

“The Administrator shall periodically review the [HAP] list established by this

subsection and publish the results thereof and, where appropriate, revise such list by

rule, adding pollutants which present, or may present, through inhalation or other

routes of exposure, a threat of adverse human health effects (including, but not

limited to, substances which are known to be, or may reasonably be anticipated to be,

carcinogenic, mutagenic, teratogenic, neurotoxic, which cause reproductive

dysfunction, or which are acutely or chronically toxic) or adverse environmental

effects whether through ambient concentrations, bioaccumulation, deposition, or

otherwise, but not including releases subject to regulation under subsection (r) of this

section as a result of emissions to the air.”

Given that nPB is a carcinogen according to the NTP, it is reasonably a threat to human health

under the Clean Air Act. Section 112(c)(9) specifies that source categories shall be delisted

where no source in the category emits HAPs in quantities which may cause a lifetime cancer

risk greater than 1 in 1 million to the individual who is most exposed to emissions of such

pollutants from the source. Therefore, for this petition, a lifetime cancer risk of 1 in 1 million

will be used as the criterion for demonstrating that nPB should be listed as a HAP.

1 http://www.envirotechint.com/products/dry-cleaning/.

http://www.envirotechint.com/products/dry-cleaning/

QMS QA ID no. 1204300.000 A0T0 1012 RR01 2

The steps in estimating cancer risks for nPB include:

1. Estimation of the cancer unit risk factor for nPB based on the NTP bioassay. Standard

EPA methodologies and software were used to develop the unit risk value.

2. Estimation of emissions for nPB. Since nPB emissions are not required to be reported,

several estimation methods were developed, depending on the available data.

3. Estimation of air concentrations and risk levels. The EPA Human Exposure Model,

Version 3 (HEM-3) was used for this purpose. HEM-3 incorporates EPA’s AERMOD

dispersion model and census tract population data to allow the estimation of risks to

populations living near facilities that use nPB.

The next three sections mirror the three steps in the risk estimation process. The final

section provides a discussion of the results and draws conclusions about the risk.

QMS QA ID no. 1204300.000 A0T0 1012 RR01 3

Estimation of Unit Risk Factor

In the NTP study, groups of 50 male and 50 female F344/N rats were exposed to nPB

vapor at concentrations of 0, 125, 250, and 500 ppm for 6 hours per day, 5 days per week for

105 weeks. A separate group of 50 male and 50 female B6C3F1 mice were exposed to the same

regimen.

NTP concluded that there was “clear evidence of carcinogenicity” for female rats based

on increased incidences of adenomas of the large intestine. NTP also concluded that there was

“clear evidence of carcinogenicity” for female mice based on increased incidences of

alveolar/bronchiolar neoplasms. Finally, NTP also concluded that there was “some evidence of

carcinogenicity” for male rats based on the occurrence of rare adenomas of the large intestine

and increased incidence of epithelial neoplasms of the skin.

Of the tumor types for which NTP concluded that there was a “clear evidence of

carcinogenicity,” the female alveolar/bronchiolar neoplasms had a higher incidence. Therefore,

the unit risk was estimated based on the tumor counts for female alveolar/bronchiolar

neoplasms. The tumor counts were 1/50, 9/50, 8/50, and 14/50 for the 0, 125, 250, and 500 ppm

exposure groups, respectively.

The unit risk was estimated using EPA’s BMDS software (EPA, 2012) and the

multistage cancer model, which is the dose-response model typically used by EPA for its cancer

assessments. The dose-response fit of the model is shown in Figure 1 and the multistage fit was

adequate. The cancer unit risk estimate, derived from the BMCL10 lower 95th

percentile bound,

is 1.85×10-3

per ppm. This value is very similar to the number derived by Finkel (2010)

(1.95×10-3

per ppm) using the same data but an older software package.

Since the NTP study exposed the rats for 6 hours per day and 5 days per week, an

adjustment is required to account for continual exposure. Therefore, the unit risk estimate was

multipled by (24/6) and (7/5). Furthermore, the unit risk was adjusted to a µg/m3 basis using the

conversion factor of 5040 µg/m3 per ppm. The final unit risk value is 2.1x10

-6 per µg/m

3.

QMS QA ID no. 1204300.000 A0T0 1012 RR01 4

Figure 1. Multistage cancer model fit for alveolar/bronchiolar neoplasms (output from EPA’s BMDS software program)

0

0.1

0.2

0.3

0.4

0 50 100 150 200 250

Fra

ctio

n A

ffe

cte

d

dose

Multistage Cancer Model with 0.95 Confidence Level

13:41 10/19 2012

BMDBMDL

Multistage CancerLinear extrapolation

QMS QA ID no. 1204300.000 A0T0 1012 RR01 5

Emissions Estimates

Several different types of facilities were considered based on the known usage of nPB.

The facility types included one degreasing application, two spray adhesive applications, and two

dry cleaners.

Degreasing

A narrow tube manufacturing facility in Collegeville, Pennsylvania switched from using

TCE for degreasing to nPB around 2008 (Matson & Associates, Inc., 2008). Facilities are

required to report HAP emissions to the Pennsylvania Department of Environmental Protection

and these emissions are provided on the Internet.2 The facility was required to report HAP/TCE

emissions to the state of Pennsylvania and those emissions dropped from 35/34 tons per year in

2007 to 5/4 in 2008 to none in 2009 and 2010. Volatile organic compound (VOC) emissions for

2007-10 went from 47 to 40 to 34 to 46 tons per year. As nPB is a VOC, it is assumed that nPB

emissions after the switch from TCE accounted for the VOC emissions in 2008-10, estimated

conservatively at 35 tons per year, comparable to the TCE emissions before the switch. The

emissions were allocated as 90% from the ceiling vents and 10% from fugitive sources.

Spray Adhesive Use

The spray adhesive emission estimates were developed from industrial hygiene

measurements from NIOSH. Specifically, NIOSH conducted health hazard evaluations (HHE)

in response to complaints from employees at two foam cushion manufacturers that used nPB.

The investigations included nPB measurements from spray booths that were used to estimate

emissions.

Fabrication Company A

NIOSH conducted a HHE in 2000 at Fabrication Company A in Thomasville, North

Carolina. The evaluation followed a request by employees concerned about nPB exposures

(NIOSH, 2002a). The HHE included an initial site visit on November 14, 2000, and an

evaluation of the local exhaust ventilation (LEV) on April 18, 2001. A follow-up investigation,

including exposure monitoring, was conducted from July 31 to August 2, 2001.

2 Link for reported emissions:

http://www.ahs2.dep.state.pa.us/eFACTSWeb/searchResults_singleFacility.aspx?FacilityID=47538

http://www.ahs2.dep.state.pa.us/eFACTSWeb/searchResults_singleFacility.aspx?FacilityID=47538

QMS QA ID no. 1204300.000 A0T0 1012 RR01 6

Fabrication Company A manufactures sofa cushions for furniture companies. The

cushions are assembled by gluing together several pieces of flexible foam. The nPB is sprayed

as an adhesive using a compressed air spray gun in a fabrication room at different spray

workstations. The emissions from the workstations are vented to the building ceiling. The

initial NIOSH investigation concluded that the spray workstations had inadequate ventilation.

Enclosure of the spray tables led to improved ventilation. After the improvements, there were

12 spray stations that emitted to 10 exhaust vents. The conditions after the changes were used

as the basis for the emission estimates.

At the follow-up visit, NIOSH measured the capture velocity at 3 feet from the LEV

hood, and estimated the exhaust flow rates from this measurement (summarized in Table 9 of

the NIOSH report). NIOSH also measured personal breathing zone concentrations of nPB on

three separate days during the follow-up visit. The breathing zone concentrations provide an

estimate of the nPB concentrations inside the hood. Therefore, the emissions can be estimated

as the hood flow rates multiplied by the concentration. Table 1 provides a summary of the

calculations.

The exhaust flow rates range from 283 to 1545 cubic feet per minute at the different

stations. The nPB concentrations ranged from 15.2 to 27.9 ppm. The emissions ranged from

0.7 to 4.4 lb/day over the different stations and are assumed to occur over an 8-hour shift. The

facility is assumed to operate for 250 days per year, leading to a range of 164 to 1109 lb/year.

The total emissions for all of the stations are 20.4 lb/day and 5104 lb/year.

It is also assumed that there are some fugitive emissions at the facility, as a result of nPB

migrating away from the workstations and not being emitted up the vent. There are industrial

hygiene measurements which show detections of nPB in other parts of the facility outside the

fabrication area that support this assumption. Therefore, it is assumed that an additional 10% of

vented emissions are emitted as a fugitive source, which is 2.0 lb/day and 510 lb/year.

QMS QA ID no. 1204300.000 A0T0 1012 RR01

7

Table 1. Emissions estimates for Fabrication Company A

Station

Exhaust

Flow Rate

(ft3/min)

(a)

Exhaust

Flow

Rate

(m3/min)

Average nPB

Concentration

(ppm)(b)

Average nPB

Concentration

(mg/m3)

Emissions

(g/min)

Emissions

(g/day)(e)

Emissions

(lb/day)

Emissions

(lb/yr)(f)

1(c)

exhaust combined with

2

2 283 8.0 15.4 77 0.6 298 0.7 164

3 755 21.4 18.0 91 1.9 929 2.0 511

4 1545 43.7 19.1 96 4.2 2017 4.4 1109

5 546 15.5 18.2 92 1.4 679 1.5 373

6 646 18.3 27.9 140 2.6 1232 2.7 677

7 917 26.0 16.4 83 2.1 1028 2.3 565

8 612 17.3 15.2 76 1.3 636 1.4 350

9 615 17.4 17.0 86 1.5 714 1.6 393

10(d)

exhaust combined with

9

11 527 14.9 25.8 130 1.9 929 2.0 511

12 593 16.8 20.2 102 1.7 819 1.8 450

Total from

exhausts 20.4 5103.7

(a) From Table 9 of NIOSH HHE report

(b) From Table 5, average nPB exposure

(c) Emissions were combined with station 2

(d) Emissions were combined with station 9

(e) Assumes emissions occur over one 8-hour shift

(f) Assumes 250 days of operation per year.

QMS QA ID no. 1204300.000 A0T0 1012 RR01 8

Fabrication Company B

NIOSH conducted a HHE for Fabrication Company B in Mooresville, North Carolina

from 1998 to 2000 (NIOSH, 2002b), following a request from the North Carolina Department of

Labor concerning nPB exposure. Custom Products manufactures seat cushions for the aircraft

industry. The cushions are made by attaching several pieces of cut foam together with the use

of nPB spray adhesive (Assembly area). The cushions are inserted into a Nomex cover, and the

nPB spray adhesive is used to seal the Nomex around the cushion (Cover area).

Following the initial NIOSH investigation, Fabrication Company B installed new spray

booths in the Assembly and Cover departments. There were three booths in the Assembly

department and six in the Cover department. The conditions following the initial investigation

and reflecting the changes made by Fabrication Company B were used as the basis for emission

estimates.

NIOSH measured the exhaust flow rates for each of the hoods (summarized in Table 13

of the NIOSH report). NIOSH also measured personal breathing zone concentrations of nPB for

the Assembly and Cover workers. The breathing zone concentrations provide an estimate of the

nPB concentrations inside the work area. Therefore, the emissions can be estimated as the hood

flow rates multiplied by the concentration. Table 2 provides a summary of the calculations.

The exhaust flow rates at each location/exhaust system range from 1823 to 4106 cubic

feet per minute at the different stations. The average nPB concentrations ranged from 14.9 to

42.2 ppm. The emissions range from 4.2 to 24.7 lb/day over the different stations and are

assumed to occur over an 8-hour shift. The facility is assumed to operate for 250 days per year,

leading to a range of 2014 to 11,841 lb/year. The total emissions for all of the stations are 131

lb/day and 32,777 lb/year.

It is also assumed that there are some fugitive emissions at the facility, as a result of nPB

migrating away from the workstations and not being emitted up the vents. There are also

industrial hygiene measurements which show detections of nPB in other parts of the facility

outside the fabrication area that support this assumption. Therefore, it is assumed that an

additional 10% of vented emissions are emitted as a fugitive source, which is 13.0 lb/day and

3278 lb/year.

QMS QA ID no. 1204300.000 A0T0 1012 RR01

9

Table 2. Emissions estimates for Fabrication Company B

Location Exhaust

System No.

Exhaust

Flow

Rate

(ft3/min)

(a)

Exhaust

Flow

Rate

(m3/min)

Average nPB

Concentration

(ppm)(b)

Average nPB

Concentration

(mg/m3)

Emissions

(g/min)

Emissions

(g/day)(c)

Emissions

(lb/day)

Emissions

(lb/yr)(d)

Assembly 1 1978 56 14.9 75.0 4.2 2014 4.4 1108

Assembly 2 1823 52 32.0 161.0 8.3 3986 8.8 2193

Assembly 3 2192 62 18.1 91.1 5.6 2711 6.0 1491

Cover 1 4106 116 42.2 212.3 24.7 11,841 26.1 6513

Cover 2 4006 113 19.6 98.6 11.2 5366 11.8 2951

Cover 3 3747 106 38.4 193.2 20.5 9833 21.6 5408

Cover 4 3960 112 28.2 141.9 15.9 7631 16.8 4197

Cover 5 3942 112 41.0 206.3 23.0 11,045 24.3 6075

Cover 6 4065 115 18.6 93.6 10.8 5167 11.4 2842

Sum from

all

Exhaust

131.1 32,777

(a) From Table 13 of NIOSH HHE report

(b) From Appendix 3 of NIOSH HHE report (average used when there were multiple values)

(c) Assumes 8-hour shift

(d) Assumes 250 days per year

QMS QA ID no. 1204300.000 A0T0 1012 RR01 10

Dry Cleaning

Blando et al. (2010) measured nPB exposures in several New Jersey dry cleaners.

Personal breathing zone concentrations ranged from non-detect to 54.5 ppm. There was

insufficient information within the publication to estimate emission rates. However, in a

personal communication, Dr. Blando indicated that the shops added about 5 gallons every few

days to the dry cleaning machines to replace evaporative losses. DrySolv is one of the most

common nPB products for dry cleaning and it has about 10.5 lb per gallon (DrySolv MSDS,

based on specific gravity of 1.33 and 95% nPB). Therefore, 21.0 lb/day were assumed to be

emitted over an 8-hour work shift, including 90% out of a ceiling vent (18.9 lb/day) and 10%

from fugitive loss (2.1 lb/day). Emissions will be assumed for 250 days/year, which would

result in emissions of 2.6 tons per year.

This estimate is very consistent with a permit issued by the Ohio Environmental

Protection Agency, which specified that a dry cleaner using nPB (Briang Garment Care, LLC

DBA Capitol Cleaners #180) limit annual emissions to 2.6 tons per year (Ohio Department of

Environmental Protection, 2011). This emissions estimate will be applied to two dry cleaners.

Summary

Table 3 summarizes the emission estimates derived in this section. The degreasing

operation had the largest emissions at 35 tons per year. The Fabrication Company B spray

adhesive process had emissions of 18 tons per year, while the other spray adhesive operation,

Fabrication Company A, had emissions of 2.8 tons per year. For dry cleaning, the emission

estimate is 2.6 tons per year.

Table 3. Summary of nPB emission estimates from different facilities

Facility nPB Emissions

(tons per year)

Degreasing 35

Fabrication Company

A 2.8

Fabrication Company

B 18

Dry Cleaner 2.6

QMS QA ID no. 1204300.000 A0T0 1012 RR01 11

It is important to recognize that the emission estimates were made without access to the

facility, specific use data provided by the facility, or stack testing data. It is possible that the

actual emissions of the facilities are different. However, the report provides a range of scenarios

that are plausible representations of facilities that use nPB. Thus, the estimates provide a basis

for characterizing the potential lifetime cancer risks associated with populations living near

facilities using nPB.

QMS QA ID no. 1204300.000 A0T0 1012 RR01 12

Estimation of Air Concentrations and Cancer Risk

The HEM-3 model was used to estimate air concentrations downwind of the nPB

facilities and associated cancer risk (EC/R Incorporated, 2007) based on the unit risk factor

derived above. HEM-3 is a streamlined inhalation risk assessment tool. It incorporates three

elements: (1) estimation of air concentrations using a dispersion model, (2) estimation of

population exposures based on the air concentrations and census tract data, and (3) estimation of

cancer risks.

HEM-3 incorporates EPA’s AERMOD air dispersion model, which is the currently

recommended air dispersion model for most applications. Meteorological data for over 60

stations are included in the model. The user is able to specify a location for each source within

the United States and the model uses data from the nearest meteorological stations. The model

identifies each census block near the facility and provides estimates of air concentrations at the

census block centroid. From this information, risk estimates are provided for populations (e.g.,

the number of people with a greater than 1 in a million lifetime cancer risk).

The model also includes a polar grid around the facility starting around 100 meters from

the facility and progressing logarithmically to 50,000 meters. Because some of the larger

buildings being modeled are in the range of 100 meters in length, the 100 meter grid was

omitted for all of the facilities except the smaller dry cleaning facilities. Each ring in the polar

grid had 16 receptors consistent the model default.

The remainder of the text in this section describes the HEM-3 model output for each of

the five facilities discussed above.

One limitation with HEM-3 is that users cannot specify emissions over only part of the

day (e.g., an 8-hour work shift) and only on work days. Therefore, a constant daily emission

rate was assumed. This limitation is not expected to have a significant impact on the model

result.

The HEM-3 input and output files are provided on a separate CD-ROM.

Degreasing Operation

The facility with the degreasing use of nPB in Collegeville, Pennsylvania was identified

using the address in Google Earth. The vent emissions were assumed to be equally distributed

from three locations on the building roof. Figure 2 shows a Google Earth picture of the facility,

QMS QA ID no. 1204300.000 A0T0 1012 RR01 13

including the three assumed vent locations and the census tract centroids near the facility. The

building dimensions were mapped and entered into the HEM-3 model. The building was

assumed to be 10 meters high based on a visual evaluation of the Google Earth image. The

three vents were assumed be 12 meters high (2 meters above the building height) with a stack

diameter of 0.5 meters, a nominally low exit velocity of 1 m/sec, and a release temperature of

293 Kelvin (room temperature). Fugitive emissions from the building were simulated as a

volume source.

Figure 2. Google Earth view of the Collegeville, Pennsylvania facility with a degreasing use of nPB. Stacks are shown on building ceiling and census tract centroids with black and white dots.

Table 4 summarizes the estimates of potential cancer risk for the census tracts near the

facility. There were 1571 people with lifetime cancer risks above 1 in 1 million and 25,871

people with lifetime cancer risks above 1 in 10 million. The maximum census tract cancer risk

was 7.1×10-6

.

QMS QA ID no. 1204300.000 A0T0 1012 RR01 14

Table 4. Summary of lifetime cancer risk estimates in census tracts for degreasing operation

Lifetime Cancer Risk Level Population

Affected

Greater than or equal to 1 in 1,000 0




Greater than or equal to 1 in 1,000,000 1571

Greater than or equal to 1 in 10,000,000 25,871

Table 5 summarizes the lifetime cancer risk estimates for the polar grid around the

facility starting at 170 meters and continuing through 20,000 meters. The table presents the

average value of 16 points for each polar grid distributed evenly in space, as well as the

minimum and maximum risk values for each polar grid distance among the 16 points. At 170

meters, the average risk was 24.6 in a million and the minimum and maximum risks were 13.2

and 42.2 in a million, respectively (all greater than 10-5

). Risks above 1 in 1 million persisted

past 1410 meters.

Table 5. Summary of lifetime cancer risk estimates for polar grid for degreasing operation

Polar Ring

Distance

(meters)

Estimated Lifetime Cancer Risk

Per Million

Average Minimum Maximum

170 24.6 13.2 42.2

290 7.5 3.6 14.5

490 3.4 1.5 6.9

830 1.5 0.6 3.3

1410 0.7 0.2 1.5

2400 0.3 0.1 0.7

4080 0.1 0.0 0.3

6930 0.0 0.0 0.1

11,770 0.0 0.0 0.0

20,000 0.0 0.0 0.0

Fabrication Company A

Fabrication Company A in Thomasville, North Carolina was identified in Google Earth

using the street address. The vent emissions were assumed to be equally distributed from 10

QMS QA ID no. 1204300.000 A0T0 1012 RR01 15

locations on the building roof as described in the last section. Figure 2 shows a Google Earth

picture of the facility and the census tract centroids near the facility. The building dimensions

were mapped and entered into the HEM-3 model. The building was assumed to be 6 meters

high based on a visual evaluation of the Google Earth image. The 10 vents were assumed be 7.3

meters high (6 vents) and 7.0 meters high (4 vents) with a stack diameter ranging from 0.4 to 1.0

meters, a nominally low exit velocity of 1 m/sec, and a release temperature of 293 Kelvin (room

temperature). The vent heights and diameters were estimated by pictometry using the image

from Google Earth. Fugitive emissions from the building were simulated as a volume source.

Figure 3. Google Earth view of Fabrication Company A in Thomasville, North Carolina. Building is shown to the right of the Regency International Blvd street label and census tract centroids with black and white dots.

Table 6 summarizes the cancer risk estimates for the census tracts near the facility.

There were no people with lifetime cancer risks above 1 in 1 million and 1065 people with

lifetime cancer risks above 1 in 10 million. The maximum census tract cancer risk was

9.1×10-7

, or just less than 1 in 1 million.

QMS QA ID no. 1204300.000 A0T0 1012 RR01 16

Table 6. Summary of lifetime cancer risk estimates in census tracts for Fabrication Company A


Affected











meters, the average risk was 2.5 in a million and the minimum and maximum risks were 1.0 and

5.2 in a million, respectively. Risks above 1 in 1 million persisted past 290 meters from the

facility.

Table 7. Summary of lifetime cancer risk estimates for polar grid for Fabrication Company A

Polar Ring

Distance

(meters)


Per Million


170 2.5 1.0 5.2

290 1.1 0.3 2.3

490 0.4 0.1 0.9

830 0.2 0.0 0.4

1410 0.1 0.0 0.2

2400 0.0 0.0 0.1

4080 0.0 0.0 0.0

6930 0.0 0.0 0.0

11,770 0.0 0.0 0.0

20,000 0.0 0.0 0.0

Fabrication Company B

The Fabrication Company B facility in Mooresville, North Carolina was identified using

the address in Google Earth. The vent emissions were assumed to be equally distributed from 9

QMS QA ID no. 1204300.000 A0T0 1012 RR01 17

locations on the building roof as described in the last section. Figure 4 shows a Google Earth

picture of the facility and the census tract centroids near the facility. The building dimensions

were mapped and entered into the HEM-3 model. The building was assumed to be 8 meters

high based on a visual evaluation of the Google Earth image. The nine vents were assumed be

10 meters high (i.e., 2 meters about the ceiling) with a stack diameter ranging of 1.0 meters, a

nominally low exit velocity of 1 m/sec, and a release temperature of 293 Kelvin (room

temperature). Fugitive emissions from the building were simulated as a volume source.

Figure 4. Google Earth view of Fabrication Company B in Mooresville, North Carolina. Building is in center of page just south of Highway 152 and census tract centroids are labeled with black and white dots.


There were 166 people with lifetime cancer risks above 1 in 1 million and 10,947 people with

lifetime cancer risks above 1 in 10 million. The maximum census tract cancer risk was

2.3×10-6

.

QMS QA ID no. 1204300.000 A0T0 1012 RR01 18

Table 8. Summary of lifetime cancer risk estimates in census tracts for Fabrication Company B


Affected











meters, the average risk was 15.7 in a million and the minimum and maximum risks were 10.2

and 21.2 in a million, respectively. Risks above 1 in 1 million persisted past 830 meters from

the facility.

Table 9. Summary of lifetime cancer risk estimates for polar grid for Fabrication Company B

Polar Ring

Distance

(meters)


Per Million


170 15.7 10.2 21.2

290 6.8 4.2 9.3

490 2.9 1.7 4.0

830 1.2 0.7 1.8

1410 0.5 0.3 0.8

2400 0.2 0.1 0.4

4080 0.1 0.0 0.2

6930 0.0 0.0 0.1

11,770 0.0 0.0 0.0

20,000 0.0 0.0 0.0

QMS QA ID no. 1204300.000 A0T0 1012 RR01 19

Virginia Dry Cleaner

nPB emissions from a dry cleaner on North Quaker Lane in Alexandria, Virginia were

simulated. We have no specific information that the dry cleaner uses nPB, but modeled the

facility to show plausible emissions for a dry cleaner in a residential area. The emissions are

assumed to emanate from a single ceiling vent. Figure 5 shows a Google Earth picture of the

facility and the census tract centroids near the facility. The building dimensions were mapped

and entered into the HEM-3 model. The building was assumed to be 7 meters high based on a

visual evaluation of the Google Earth image. The vent was assumed be 8 meters high (i.e., a

meter about the ceiling) with a stack diameter of 0.5 meters, a nominally low exit velocity of 1

m/sec, and a release temperature of 293 Kelvin (room temperature). Fugitive emissions from

the building were simulated as a volume source.

Figure 5. Google Earth view of a dry cleaner on North Quaker Lane (Highway 402) in Alexandria, VA. Building is in center of the page and census tract centroids are labeled with black and white dots.


There were 1057 people with lifetime cancer risks above 1 in 1 million and 12,435 people with

lifetime cancer risks above 1 in 10 million, with a maximum census tract cancer risk of 5.0×10-6

.

QMS QA ID no. 1204300.000 A0T0 1012 RR01 20

Table 10. Summary of lifetime cancer risk estimates in census tracts for Virginia dry cleaner


Affected













facility.

Table 11. Summary of lifetime cancer risk estimates for polar grid for Virginia dry cleaner

Polar Ring

Distance

(meters)


Per Million


100 5.4 2.4 10.5

170 2.3 1.0 4.3

290 1.0 0.4 1.8

490 0.4 0.2 0.7

830 0.2 0.0 0.3

1410 0.1 0.0 0.1

2400 0.0 0.0 0.1

4080 0.0 0.0 0.0

6930 0.0 0.0 0.0

11,770 0.0 0.0 0.0

20,000 0.0 0.0 0.0

QMS QA ID no. 1204300.000 A0T0 1012 RR01 21

Massachusetts Dry Cleaner

nPB emissions from a dry cleaner on Main Street in Waltham, Massachusetts were

simulated. We have no specific information that the dry cleaner uses nPB, but modeled the

facility to show plausible emissions for a dry cleaner in a residential area. The emissions are

assumed to emanate from a single ceiling vent. Figure 6 shows a Google Earth picture of the

facility and the census tract centroids near the facility. The building dimensions were mapped

and entered into the HEM-3 model. The building was assumed to be 7 meters high based on a

visual evaluation of the Google Earth image. The vent was assumed be 8 meters high (i.e., a

meter about the ceiling) with a stack diameter of 0.5 meters, a nominally low exit velocity of 1

m/sec, and a release temperature of 293 Kelvin (room temperature). Fugitive emissions from

the building were simulated as a volume source.

Figure 6. Google Earth view of a dry cleaner on Main Street in Waltham, Massachusetts. Building is in center of the page and census tract centroids are labeled with black and white dots.


There were 7 people with lifetime cancer risks above 1 in 1 million and 769 people with lifetime

cancer risks above 1 in 10 million. The maximum census tract cancer risk was 1.1×10-6

.

QMS QA ID no. 1204300.000 A0T0 1012 RR01 22

Table 12. Summary of lifetime cancer risk estimates in census tracts for Massachusetts dry cleaner


Affected













facility.

Table 13. Summary of lifetime cancer risk estimates for polar grid for Massachusetts dry cleaner

Polar Ring

Distance

(meters)


Per Million


100 4.3 2.7 6.7

170 1.7 1.0 2.7

290 0.5 0.3 1.0

490 0.2 0.1 0.3

830 0.1 0.1 0.1

1410 0.0 0.0 0.1

2400 0.0 0.0 0.0

4080 0.0 0.0 0.0

6930 0.0 0.0 0.0

11,770 0.0 0.0 0.0

20,000 0.0 0.0 0.0

QMS QA ID no. 1204300.000 A0T0 1012 RR01 23

Summary

Table 14 summarizes the maximum nPB cancer risk estimates by census tract and for the

polar grid. The maximum risks are greater than 1 in 1 million for 4 of the 5 facilities by census

and all of the facilities by the polar grid (minimum distance of 170 meters for non-dry cleaners

and 100 meters for dry cleaners). For the polar grid estimates, three of the five facilities had

risks greater than 10 in a million. These results sufficiently demonstrate that nPB emissions

have the potential to result in cancer risks greater than 1 in 1 million, the threshold for

regulation of sources of carcinogens under the Clean Air Act.

Table 14. Maximum estimated nPB cancer risks for each facility by census tract and polar grid

Facility Maximum Census

Tract Risk

Maximum Polar

Grid Risk (a)

Degreasing operation 7.1×10-6

4.2×10-5

Fabrication Company

A 9.1×10

-7 5.2×10

-6

Fabrication Company

B 2.3×10

-6 2.1×10

-5

Virginia Dry Cleaner 5.0×10-6

1.1×10-5

Massachusetts Dry

Cleaner 1.1×10

-6 6.7×10

-6

(a) Minimum distance of 100 meters for dry cleaners and 170 meters for other facilities

It is important to note that the analysis above only considers five facilities. There is a

large pool of potential facilities that could use nPB. Some of these facilities may have higher

emissions that those considered in this analysis, and some may have populations closer to the

facility than for the facilities modeled here. In these cases, the risks would be even higher.

QMS QA ID no. 1204300.000 A0T0 1012 RR01 24

Conclusions

This report presents an analysis to estimate potential cancer risks resulting from

industrial uses of nPB, a solvent that is used in a variety of industrial operations to replace

chlorinated solvents. Despite being marketed as “non-hazardous,” nPB has been reported to

cause neurological and reproductive effects in workers and has been identified as a carcinogen

by the NTP based on 2-year bioassays in rodents.

The risk estimation process had three steps: (1) estimation of a cancer unit risk factor for

nPB, (2) estimation of emissions of nPB from different industrial operations, and (3) estimation

of downwind concentrations and population risk using EPA’s HEM-3 dispersion model.

Five facilities were modeled including a facility using nPB as a degreaser, two facilities

using nPB as a spray adhesive, and two dry cleaning facilities. For 4 of the 5 facilities, cancer

risks exceeded 1 in 1 million at the centroid of at least one nearby census tract. All five

facilities had nearby locations where the risks exceeded 1 in 1 million.

QMS QA ID no. 1204300.000 A0T0 1012 RR01 25

References

EC/R Incorporated (2007) The HEM-3 user’s guide. Version 1.1.0 (AERMOD version).

Prepared by EC/R Incorporated for EPA. EPA Contract 68-D-06-119.

EPA (2012) Benchmark dose technical guidance. EPA/100/R-12/001.

Finkel, A (2010) Increased toxicity and carcinogenicity of n-propyl bromide (1-bromopropane)

relative to perchloroethylene. Supplemental report to the city of Philadelphia

Department of Public Health/Air Management Services.

Matson & Associates, Inc. http://www.pennfuture.org/userfiles/PDFs/M&A-

March7PresentationToDEP.pdf

NIOSH (2002a) NIOSH health hazard evaluation report. HETA #2000-0410-2891. STN

Cushion Company. Thomasville, North Carolina.

NIOSH (2002b) NIOSH health hazard evaluation report: HETA #98-0153-2883. Custom

Products, Inc. Mooresville, NC.

NTP (2011) NTP technical report on the toxicology and carcinogenesis studies of 1-

bromopropane (CAS No. 106-94-5) in F344/N rate and B6C3F1 mice. NTP Publication

No. 11-5906.

Ohio Environmental Protection Agency (2011) Division of Air Pollution Control Permit-to-

Install and Operate for Briang Garment Care, LLC DBA Capitol Cleaners #180.

http://www.pennfuture.org/userfiles/PDFs/M&A-March7PresentationToDEP.pdf

http://www.pennfuture.org/userfiles/PDFs/M&A-March7PresentationToDEP.pdf

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