Overview of the

Final TCE Workplan Risk Assessm

Tala R. Henry, Ph.D.Director, Risk Assessment DivisionOffice of Pollution Prevention and Toxics

Trichloroethylene (TCE)

CASRN 79‐01‐6

July 29, 2014
Main Risk Conclusions

 Workers and occupational bystanders at sma

commercial degreasing facilities and dry clea

facilities

 Use TCE‐based degreasers and spotting agents, re

 Potential cancer risk concerns and short‐term and 

non‐cancer risks

 Consumers and residential bystanders

 Use of TCE‐containing degreasers and spray‐appli

protective coatings

 Potential short‐term non‐cancer risks

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OPPT’s Basis for Selecting TCE for Risk Evalua

 TCE’s human health hazards

– Human carcinogen, non‐cancer effects

 High exposure potential

– Produced and imported into the U.S. in large quantities

(> 250 million pounds/yr)

– Toxic Release Inventory (TRI) database‐ TCE predominantly r

– Inhalation is predominant exposure pathway (high volatility)

Office of Pollution Prevention a

Industrial Uses (98.3%) Consumer Uses (1.7%)

• 83.6% ‐ intermediate for manufacturing of

refrigerant

• 14.7% ‐ solvent for metals degreasing

• Automotive degreasing products• Arts/crafts/home fixative or clea

• Home office toner aid

• Home mirror edge sealant

Source: Glauser and Funda, 2012 a

Footnotes: (a) This source material includes data or information derived from IHS Products provided to the products have been provided to the U.S. EPA for its internal use and in the context of a license agreement. 

accessing this material, you agree that IHS is not liable to you or any third party for your use of and/or relia

and information contained in this document, and any such use shall be at your own risk.
Scope of the Assessment

 Focus on the human health inhalation hazard

cancer and non‐cancer) for the following use

─ Commercial use as a solvent degreaser─ Commercial use as a spotting agent in dry cleaning─ Consumer use as a solvent degreaser

─ Consumer use as a clear protective coating spray in

arts/crafts

 Environmental risks were not evaluated in th

assessment due to minimal concerns for ecol

hazards

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Populations, Exposure Scenarios and

Heath Effects of Concern

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Use Scenario Exposure Duration Population of Interest Points of 

(P

Small commercial degreaser Chronic exposure (2 hrs per 8‐

hr workday, 5 days/week)

Adult workers

(>16 yrs)2

• Range of hazard va

cancer inhalation enervous system, imreproductive systeeffects) as evaluatassessment.

• Cancer effects usin

risk

Bystander to small

commercial degreaser

Chronic exposure1 Adult workers

(>16 yrs)2

Worker at dry cleaning facility Chronic exposure (8‐hr

workday, 5 days/week)

Adult workers

(>16 yrs)2

Occupational bystander in dry

cleaning facility

Chronic exposure1 Adult workers

(>16 yrs)2

Hobbyist‐degreaser use Acute exposure (1 hr per event,

2 events per month)

Adult consumers2

>16 yrs old) • Hazard value for fe

malformations (Joevaluated by the 2assessment

Bystander to hobbyist‐

degreaser use

Acute exposure1 Individuals of all

ages3

Hobbyist‐clear protecting

coating spray

Acute exposure (0.5 hr per

event, one event per week)

Adult consumers2

(>16 yrs old)

Bystander to hobbyist‐clear

protecting coating spray

Acute exposure1 Individuals of all

ages3

Footnote: (1) Individual is in the same building, but no direct exposure; (2) Women of childbearing age includi

are included in the adult worker and consumer population; (3) bystanders of all ages near the exposure source 
Occupational Exposure Assessment: Deg

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Occupational TCE Inhalation Exposures:

Small Commercial Degreaser/Bystander

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Population

Exposed

Workplace Exposure Concentrations

(24‐hr TWA3 in ppm)

Acute

Chronic

Non‐cancer Cancer

With LEV No LEV With LEV No LEV With LEV No LEV

Workers1 0.1 to 7 1 to 66 0.07 to 5 0.7 to 47 0.04 to 3 0.4 to 27

Occupational

bystanders2 0.01 to 6 0.1 to 57 0.01 to 4 0.1 to 41 0.005 to 2 0.05 to 23

1Workers are directly involved with degreasing operations.2 Occupational bystanders have the potential to be exposed to TCE but they are not directly

involved with degreasing operations

3 TWA = Time weighted average4 LEV = local exhaust ventilation

Type of Facility

Potential Workplace TCE Inhalation Exposures

(8‐hr TWA)

Near‐Field Far‐Field

LEV

(ppm)

No LEV

(ppm)

Number of

Workers

LEV

(ppm)

No LEV

(ppm)

Numbe

Worke

Small commercial

degreasing facility 0.3 to 20 3 to 197 8,895 0.04 to 17 0.4 to 172 21,34
2011 IRIS Assessment

 Comprehensive review of hazard/dose‐response studies of TCE a

metabolites in 2011 IRIS assessment

– Organization of toxicity review by tissue/system

– Multiple lines of evidence supporting major hazard/dose‐response 

(human epidemiologic data, animal tox data, mechanistic data, PBP

meta‐analysis of cancer epidemiology, BMD modeling, uncertainty/

analyses)

 TCE is readily absorbed/distributed via oral, dermal and inhalatio

(metabolism occurs and plays a role in hazard)

– Crosses the placenta and can be transferred via breast milk

– Is considered a human carcinogen (IARC, NTP, EPA)

– Non‐cancer effects include: neurotoxicity, immune effects, liver/kid

reproductive, developing fetus (most sensitive endpoint)

Office of Pollution Prevention a
OPPT Approach to Hazard/Dose‐Response Assessment:

Non‐Cancer and Cancer Effects Non‐cancer: oral and inhalation studies deemed suitable by the 2011 

 Different health endpoints used to evaluate acute or chronic exposure

 PBPK model used to derive different human equivalent concentrations (H

 HEC at 50th, 95th and 99th percentiles calculated

─ HEC99 is protective for a sensitive individual and preferred in this asse

other percentiles

 Used same endpoint/study‐specific UFs applied to PBPK‐derived HECs in t

assessment

 Risk metric= margin of exposure (MOE)

= Human Equivalent Concentration99 ÷ Human Exposure

 Interpretation of potential risk based on benchmark MOE (10)

 Cancer: Used the inhalation unit risk (IUR) derived in the 2011 IRIS ass

worker scenario (chronic exposure)

 Target sites: kidney cancer, non‐Hodgkin’s lymphoma, and liver cancer

 IUR= 410‐6 per μg/m3 (210‐2 per ppm)

 Risk= Human Exposure x IUR

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Risk Characterization: Cancer

Small Commercial Degreasers and Bystander

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0.1 1 10 100 1000 10000 

Degreaser + LEV‐‐Typical Exposure

Degreaser No LEV‐‐Typical Exposure

Degreaser + LEV‐‐Worst Case

Degreaser No LEV‐‐Worst Case

Bystander + LEV‐‐Typical Exposure

Bystander No LEV‐‐Typical Exposure

Bystander + LEV‐‐Worst Case

Bystander No LEV‐‐Worst Case

Degre

LEV‐‐

Exp

Degreaser +

LEV‐‐Worst

Case

Degreaser No

LEV‐‐Worst

Case

Bystander +

LEV‐‐Typical

Exposure

Bystander No

LEV‐‐Typical

Exposure

Bystander +

LEV‐‐Worst

Case

Bystander No

LEV‐‐Worst

Case

Number of Human Cancer Cases Per Million 500000 50000 1000 100 500000 50000 8

Number of Human Cancer Cases Per Million

1x10‐4 1x10‐5 1x10‐6
Risk Characterization: Chronic Non‐Cancer Risks for Oc

Exposures

Office of Pollution Prevention a

 Potential chronic non-cancer risks for a range of human health effe

occupational degreaser and spot cleaning exposure scenarios (i.e.below the benchmark MOE).

 Greatest concern was for developmental effects (i.e., fetal cardiac 

followed by kidney effects and then immunotoxicity, with an overall risk for the degreaser exposure scenarios. In general, this concern irrespective of the type of exposure (typical vs worst case) and the room ventilation (LEV vs no LEV).

 Potential chronic risks for reproductive effects and neurotoxicity for 

worker exposure scenarios and most of the degreaser bystander escenarios. However, the risk concerns for these effects were repospot cleaning worker/bystander scenarios and generally attributed conditions without room ventilation.

 Potential chronic risks for liver effects although the risks were less 

those reported for other health effects. These risks were found ondegreaser worker/bystander exposure worst case scenarios and thcleaning worker/bystander worst case scenarios with no LEV.
Risk Characterization: Acute Non‐Cancer Ris

Occupational and Consumer Exposures

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 Potential acute non-cancer risks for developmental effects (i.

defects) for most occupational and residential exposure scenMOEs were below the benchmark MOE of 10).

 Degreaser exposure scenarios showed greater acute risks fo

developmental effects than those reported for the spot clean

scenarios. 
Acknowledgements

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Authors and Contributors

Marcus Aguilar David Lyn

Kay Austin Nhan Nguy

Stanley Barone Nicholas Nairn

Iris Camacho Laura Niels

Rehan Choudhary Justin Robe

Lynn Delpire (retired) Louis Scara

Cathy Fehrenbacher Yvette Selby-Mo

Kathy Hart Todd Stede

David Tob

Contract Support

Portions of the document were developed with s

ERG and Syracuse Research Corporatio

Special thanks to Joe Coble and his OSHA staff 

TCE monitoring data for degreasing facili