Characterization of Massachusetts

Tollbooth Worker Exposure to

Particulate Matter & Toluene

An Exposure Assessment by:

Peter Hynes & Andrea Di Perna

May 2nd, 2014

Environmental Health Issue

• Air pollution is one of the world’s largest

Environmental Health risks.

• According to WHO, one out of every eight deaths

worldwide is attributable to air pollution.

• Air-borne particulate matter and volatile organic

compounds have been shown to cause adverse health

outcomes with both acute and chronic exposures.

(WHO, 2014)

Problem in Massachusetts (VOC’s)

VOC’s from mobile sources

(cars) decreased 69% from 1990

- 2008. BUT…..

Mobile sources still make up

about a quarter of all VOC’s

emitted in Massachusetts.

(MassDEP 2012)

Why do a tollbooth study?• Occupational exposure to traffic pollution of tollbooth workers has been

a concern due to potential health effects.

• Tollbooth workers are potentially exposed to higher levels of air

pollutants due to their close proximity to a traffic source.

• Few studies are available in the U.S. that characterize exposure at

tollbooths.

• More studies are available that examine PM2.5, PM10, ultrafine particles

and carbon monoxide than VOCs.

• Gap in knowledge for VOCs.

Objectives

• Characterize tollbooth worker exposure to

Toluene (and PM 2.5)

• Compare exposure between rush hour and non-

rush hour periods

• Compare exposure inside and outside

tollbooths

• Compare fast lane to non-fast lane exposure

Toluene (C6H5CH3)

• Colorless Solvent

• Used in:o gasoline

o paint

o paint thinner

o household cleaners

o adhesive(ATSDR 2001)

Toluene: ToxicologyMajor Route of Exposure - Inhalation

• Car exhaust

• Cleaning in enclosed areas

• Intentional misuse

Health effects

• Dizziness

• Headache

• Confusion

• Respiratory and eye irritation

Sensitive Population

• Babies are more sensitive because they lack the biotransformation

enzymes to detoxify toluene (ATSDR 2001)

Toluene: Toxicology (ADME)

Absorption:

• Rapid (appears in blood within 15 minutes of exposure)

• 50% of dose absorbed, more in concentrated space

Distribution:

• Can be stored in adipose tissue

• Associates with plasma and RBC’s

• Prefers highly vascularized tissue(target organ system = CNS)(ATSDR 2001)

Metabolism:

• Broken down by CYP2E1 (among others)

• Major pathway is acetylation to Hippuric Acid

• Can form Mercapturic acid and others as minor pathways

• Metabolism increases hydrophilicity(parent compound = ultimate

toxicant)

Excretion:

• Rapidly excreted as hippuric acid in urine

• Hippuric Acid bad biomarker, Blood is best

• Some excretion of unmetabolized Toluene through expired air(ATSDR 2001)

Toluene: Toxicology (ADME)

Toluene Regulatory Standards

• OSHA PEL = 200 ppm (750 mg/m3) (OSHA 2012)

• NIOSH REL= 100 ppm (375 mg/m3) (NIOSH 1973)

• ACGIH TLV = 20 ppm (75 mg/m3) (ACGIH 2007)

• Carcinogenesis - Unable to be classified

• MassDEP - 80 ug/m3 (21.23 ppb) 24 HR TWA(MassDEP 2014)

Exposure-Disease Model for Toluene

Data Collection

• Population: Toll booth Workers

• Permissions: MassDOT

• Location: Boston, MA

o Ted Williams Tunnel (Exit 26)

o Allston/Brighton Exchange (Exit 18)

o Weston (Exit 15)

Data Collection: Instrumentation

• Use ppbRAE (10) for Toluene measurements (continuous)– Calibrate using: toluene

zeroing tubes (low end), and ten ppm isobutylene standard (high end)

– Last factory calibrated in 2007

– Flow rate: 500 cc/min.

Data Collection: Timing● Rush Hour: 6:00AM-9:00AM

● Non-Rush Hour: 9:30 AM-12:00PM

● 15-minute rounds, 2 per plaza, split into 5-minute intervals,

each treated as a separate data point

Toll Booth

Data Analysis

• Adjustment of meters• Needed to determine the difference between meters

• Ran them together in a non-source room

• Adjusted by the mean of the difference between meters

• Null values• Excluded values associated with meter error

• Weston Tolls

• Classified measurement with “negative values” as zero

Data Analysis (continued) • Tested for normality

• Data determined to be non-normal by Shapiro-Wilk Test

• Log Transforming data didn’t help

• Used all non parametric tests

• Rush Hour vs. Non-Rush Hour were not independent samples

Descriptive Statistics

Table 1: Descriptive Statistics

N Missing Min. Max. Mean SD Median

PM 2.5

(mg/m3)54 7 0.007 0.040 0.019 0.005 0.017

TOLUENE

(ppb)54 15 0 134 35 36 22

Table 2: Toluene Comparison Tests (ppb)

N Median (ppb)Test

Statisticp-value Test Conclusion

Rush Hour v.

Non-Rush Hour

RH: 18

NRH: 21

RH: 37

NRH: 9M=3 0.21

Wilcoxon

Signed Rank

No Sig.

Difference

Fast Pass v.

Non-Fast Pass

FP: 14

NFP: 12

FP: 24

NFP: 52 S=186 .219

Wilcoxon

Rank Sum

No sig.

Difference

Inside v. OutsideIn: 12

Out: 13

In: 52

Out:13S=192 0.05

Wilcoxon

Rank sum

No Sig.

Difference

Toluene Results

Tracking Trucks-Toluene

Tracking Trucks- PM 2.5

Discussion: Toluene• OSHA standard = 200 ppm

• NIOSH = 100 ppm

• ACGIH = 20 ppm

• MassDEP Ambient Air (24 hour average) = 21 ppb

• Our Mean = 35 ppb

• Difference between inside vs. outside (p=0.05)

• Trucks may cause spikes in air concentrations

• Implications

o Mean concentration < OSHA, NIOSH, ACGIH standards;

exceeds MassDEP ambient air

o Inside vs. Outside: Toluene may accumulate in booth

Results Compared to the Literature

Lee et al. 2002:

• Toluene mean = 20.21-22.48 ppb (Compared to mean = 86 ppb)

• VOC samples from breathing zone; automatic data loggers

• Placement of monitor may affect sample

Sapkota et al. 2005:

• Toluene mean=9.75 ug/m3 indoor, 17.9 ug/m3 outdoor (2.54 ppb indoor,

4.66 ppb outdoor) (Our mean = 86 ppb)

• Significant differences in rush hour vs. non-rush hour

LimitationsHow could they have affected our results?

• Worker preferences about monitor placement

• Proximity to breathing zone inconsistent

• Brief period of rain at Weston tolls

• May affect monitor reading

• Limits on monitor memory

• Missing toluene data at Weston tolls

• Possibility of confounders affecting Toluene Concentration

• Heaters inside tollbooth

• Limited sample size

• Time constraints due to escort and praticality

Addressing the Public Health IssuesTo decrease exposures MassDOT could:

• Require all 6,8-wheel trucks to travel

through fast pass lane• Our data supports the literature that concludes trucks

cause spikes in Toluene exposure

• Update ventilation systems if necessary

(ages of tollbooths vary)• Literature (Sapkota et.al) showed inside toll booth is

protective when positive pressure ventilation is used

• Change all plazas to Fast Pass only• Literature (Currie & Walker et.al.) show changing toll

booths to fast pass only increases infant health in

surrounding communities

* Success of these proposals should be verified by more extensive studies

Acknowledgements

• Dr. McClean,

BUSPH

• Rebecca Laws,

BUSPH

• Mike MacQueen,

MassDOT

• Rick McCullough,

MassDOT

References3M Occupational Health and Environmental Safety Division. 2010. Respirator Selection Guide. Retrieved from

http://www.lbl.gov/ehs/chsp/html/OdorThresholds-3MRespiratorSelectionGuide.pdf.

ATSDR. 2001. Toluene. Retrieved from http://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=160&tid=29.

Currie, J. & Walker, R. 2012. Traffic congestion and infant health: Evidence from E-ZPass. Retrieved from www.princeton.edu.

EPA. 2007. The chemical toxicology of particulate matter. Retrieved from

http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.abstractDetail/abstract/8457.

EPA. 2012. Air and radiation. NAAQS. Retrieved from http://www.epa.gov/air/criteria.html.

EPA. 2013. Particulate matter (PM). Retrieved from http://www.epa.gov/airquality/particulatematter/.

EPA. 2014. State recommendations for area designations. Retrieved from

http://www.epa.gov/airquality/particlepollution/designations/2012standards/state.htm.

Lai, C.H. et al. (2004) Exposure to fine particulate matter (PM2.5) among highway toll station workers in Taipei: Direct and

indirect exposure assessment. Archives of

Environmental Health

59(3):138-148.

Lee, C. et al. (2002). Exposure assessment on volatile organic compounds (VOCs) for tollway station workers via direct and

indirect approaches. Journal of

Occupational Health 44:294-300.

Retrieved from http://joh.sanei.or.jp/pdf/E44/E44_5_02.pdf.

References (Cont’d)MassDEP. 2012. Summary 2008 Massachusetts statewide emissions. Retrieved from

http://www.mass.gov/eea/docs/dep/air/priorities/08pei-data.pdf.

MassDEP. 2014. Ambient Air Toxics Guidelines. Retrieved from

http://www.mass.gov/eea/agencies/massdep/toxics/sources/air-guideline-values.html#notes.

Mass. Executive Office of Energy and Environmental Affairs. 2014. 310 CMR 6.00: Ambient air quality standards. Retrieved

from http://www.mass.gov/eea/agencies/massdep/air/regulations/310-cmr-6-00-ambient-air-quality-standards.html#1.

NIOSH. 1998. Manual of analytical methods, 4th edition. Retrieved from http://www.cdc.gov/niosh/docs/81-123/pdfs/0600.pdf.

OSHA. 2012. Toluene. Retrieved from https://www.osha.gov/dts/chemicalsampling/data/CH_272200.html.

Sapkota et al. 2005. Tollbooth workers and mobile source-related hazardous air pollutants: How protective is the indoor

environment? Environmental Science Technology 39(9):2936-2943. Retrieved from

http://pubs.acs.org/doi/abs/10.1021/es0489644.

WHO. 2014. 7 million premature deaths annually linked to air pollution. Retrieved from

http://www.who.int/mediacentre/news/releases/2014/air-pollution/en/.

Image Sources:

http://blogs.wickedlocal.com/massmarkets/files/2012/05/tolls-gh-022609-15.jpg

http://techalive.mtu.edu/envengtext/ch12_health.htm

http://www.ph.ucla.edu/epi/bioter/anthapha_id_a.html

http://www.cardozaplayer.com/article_details.php?cid=40&contentType=1&typeSub=0