May 30, 2003 American Lung Association of Pennsylvania 1 Health Effects of Diesel Exhaust Kevin M. Stewart Director of Environmental Health American Lung

May 30, 2003American Lung Association of

Pennsylvania1

Health Effects of Diesel ExhaustKevin M. Stewart

Director of Environmental Health

American Lung Association of Pennsylvania


Pennsylvania2

Outline

Diesel Exhaust Composition Diesel Exhaust Health Effects

Overview Specifics, notably cancer Populations at Risk

Key Steps / Conclusion


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What is Diesel Exhaust?


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Composition of Diesel Exhaust Complex mixture of thousands of

chemicals Gases and fine particles Over forty air contaminants

recognized as toxicants,

carcinogens, reproductive

and developmental hazards,

endocrine disruptors


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Composition of Diesel Exhaust Gas phase

Oxygen Carbon dioxideNitrogen Carbon monoxideWater vaporNitrogen Oxides (especially NO)Sulfur Compounds

(especially Sulfur Oxides)Volatile Organic CompoundsLow MW Hydrocarbons…


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Composition of Diesel Exhaust

Gas phase components of toxicological significance

Aldehydes (formaldehyde, acetaldehyde, acrolein)

Benzene1,3-butadienenitrosaminespolycyclic aromatic hydrocarbons (PAHs)nitro-PAHs


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Composition of Diesel Exhaust Particulate phase

Mostly elemental carbon (soot) About 20% to 40% adsorbed organic

compounds Also sulfate, nitrate, metals, other trace elements The most toxicologically relevant adsorbed

compounds (less than 1% of PM by mass):

- PAHs

- Nitro-PAHs

- Oxidized PAH derivatives 92% of mass is in particles smaller than 1 micron


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Substances in Diesel Exhaust Listed by the California Air Resources Board as Toxic Air Contaminantsacetaldehyde cobalt compounds nickel

acrolein cresol isomers 4-nitrobiphenyl

aniline cyanide compounds phenol

antimony compounds dibutylphthalate phosphorus

arsenic dioxins and dibenzofurans POM, including PAHs

benzene ethyl benzene and their derivatives

beryllium compounds formaldehyde propionaldehyde

biphenyl hexane selenium compounds

bis[2-ethylhexyl]phthalate lead (inorganic) styrene

1,3-butadiene manganese compounds toluene

cadmium mercury compounds xylene isomers, mixtures

chlorine methanol o-xylenes

chlorobenzene methyl ethyl ketone m-xylenes

chromium compounds naphthalene p-xylenes


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Diesel Emissions Inventory

Nationwide, 2001 data show diesel emissions at ~ 4% of PM2.5 inventory. (~11% excluding natural and

miscellaneous sources) Urban Centers

Diesel PM estimated up to 10% to 36% in some western cities.

Nitrogen Oxides – nearly one third! Over decades, nonroad diesel has over-

taken decreasing onroad diesel emissions. Recent diesel emissions trends have been

relatively stagnant.


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Estimating Exposure to Diesel Exhaust

Use of particulate phase as surrogate for all: Typical indoor level about half of higher risk areas Near-highway exposures up to about 5 times

average outdoor levels On school buses, average PM2.5 concentrations

often 5 to 10 times higher than ambient, especially when buses are queued and idling.

PM10 concentrations average ~ 2 mcg/m3 but has been detected at 125 mcg/m3 above background (w/ windows closed) following an urban transit bus


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Diesel Health Effects Overview


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Weight of Evidence Approach to Understanding Risk biological plausibility supporting evidence from animal studies,

genotoxicity consistency of response broad-based evidence upward trend in exposure-response detectable association at environmental levels effects remain after adjusting for potential bias strong association for highest exposure groups confounding cannot explain association


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Diesel Exhaust is a “Quadruple Whammy”

for Public Health Carcinogens Toxins Fine Particulate Matter Nitrogen oxides


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Whammies 1 and 2 Carcinogens

Lung Bladder

Toxins Nervous Endocrine Reproductive Immune Developmental Liver Kidney


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Whammy 3 Fine Particulate Matter

Premature death Increase respiratory illnesses Exacerbate asthma

Symptom days Attacks ER visits Hospitalization


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Whammy 4 Nitrogen oxides

Ozone precursor … Increase in respiratory illnesses Decrease in lung function growth


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Specific Health Effects


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Specific Highlights Diesel emissions are a significant source of the fine

particulate matter that may be responsible for about

50,000 premature deaths in the U. S. every year. Nationwide, expected lifetime cancers from diesel

particulate in the U. S. population have been

conservatively estimated at about 125,000. EPA has estimated that the diesel engine and fuel rule

approved in February of 2001 will prevent 8,300

premature deaths, 360,000 asthma attacks, and

1.5 million lost work days annually.


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Specific Highlights

STAPPA and ALAPCO estimated in 2002 that if EPA

were to adopt and implement a NONROAD heavy duty

diesel rule consistent with those organizations’

recommendations: Approximately 8,500 premature deaths per year could be

avoided. In 2030 the total annual monetized health-related

benefits associated with reductions in particulate

matter emissions reductions would be more than

$67 billion (1999 dollars).


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Non-cancer Health Effects from Short-term Exposure

Acute irritation Respiratory symptoms (e.g., cough) Neurophysiological symptoms (e.g., nausea) Compromised pulmonary function Increase in biochemical markers associated with

allergy Asthma exacerbation Insufficient data for specifying “guidance” level


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Non-cancer Health Effects from Long-term Exposure

Greater cough and phlegm Asthma induction Animals also show decreased resistance to

infection, increased chronic lung inflammation and tissue changes

Insufficient human data for specifying “guidance” level, but US EPA has set Reference

Concentration at 5 micrograms/m3


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Diesel Emissions as a Carcinogen


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Estimated Cancers from Diesel ParticulateState and Territorial Air Pollution

Program Administrators

and Association of Local Air Pollution Control Officials

(STAPPA/ALAPCO)

Cancer Risk from Diesel Particulate: National and

Metropolitan Area Estimates for the United States,

March 15, 2000.


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Estimated Cancers from Diesel Particulate

ENTIRE UNITED STATES 125,110 20 Largest Metropolitan AreasMetropolitan Area CancersLos Angeles 16,250New York 10,360Chicago 4,535Washington/Baltimore 3,750San Francisco 3,510Philadelphia 3,085Boston 2,900Detroit 2,810Dallas/Fort Worth 2,470

- continued


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Estimated Cancers from Diesel Particulate

20 Largest Metropolitan Areas - continuedMetropolitan Area CancersHouston 2,270Atlanta 1,930Miami/Fort Lauderdale 1,880Seattle 1,765Phoenix 1,510Cleveland 1,500Minneapolis 1,460San Diego 1,430St. Louis 1,320Denver 1,220Pittsburgh 1,210


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Cancer Risk Assessments of Diesel Exhaust ORGANIZATION YEAR

CONCLUSIONNational Institute for Occupational Safety and Health 1988

potential occupational carcinogenInternational Agency for Research on Cancer (WHO) 1989

probable human carcinogenState of California 1990

known to cause cancerHealth Effects Institute 1995& World Health Organization 1996

consistency in showing weak association between exposure to diesel exhaust and lung cancer


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Cancer Risk Assessments of Diesel Exhaust ORGANIZATION YEAR

CONCLUSIONCalifornia EPA (Staff Recommendation) 1998

“may cause an increase in the likelihood of cancer”California Air Resources Board 1998

diesel particulate emissions are a toxic air contaminantNational Toxicology Program 1998

“diesel exhaust particulate is reasonably anticipated to be a human carcinogen”

U.S. Environmental Protection Agency 2002 likely to be carcinogenic to humans by inhalation at environmental levels of exposure


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Carcinogenic Potential of Diesel Emissions

Known carcinogens in vapor phase Benzene Formaldehyde 1,3-butadiene Ethylene dibromide

Adsorbed onto particles 3 PAHs (including BAP) classified as

probably carcinogenic to humans At least 16 hydrocarbons classified as

possibly carcinogenic to humans These do not account for all of the cancer risk associated with diesel exhaust.


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Meta-analysis by California Office of Environmental Health Hazard Assessment on diesel exhaust and lung cancer: Clear positive relationship between

occupational diesel exhaust and lung cancer

Cigarette smoking removed as confounder

Consistent with causal relationship Association with 40% increase in

relative risk


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A similar meta-analysis on dieselexhaust and bladder cancer (January,2001 by Boffetta and Silverman inEpidemiology): Found an increased risk of between

18% and 76% among occupationallyexposed individuals (bus and truckdrivers, railroad and shipyardworkers)


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People are exposed to hundreds of times theamount of carcinogens the Clean Air Actrecognizes as a reasonable precaution (one-in-a-million): In 1996 the national average lifetime cancer

risk from breathing outdoor hazardous

pollutants was 1 in 2,100. Mobile sources: 93% of this risk Diesel emissions: 89% of the risk:

28% from on-road sources (e.g., trucks) 60% from nonroad sources (industrial,

construction and farm equipment)


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Populations at Risk (1998 data)

State Population Emphysema Chronic Bronchitis

Adult Asthma (>= 18 yr) Pediatric Asthma (< 18 yr)

NJ 8,095,542 91,513 277,593

210,480 105,914

PA 12,002,329 137,136 415,982

315,416 151,857

DE 744,066 8,461 25,666

19,460 9,557

MD 5,130,072 57,572 174,642

132,420 68,593


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Populations at Risk (1998 data) (continued)

State Population Under 14 Years 65 Years and Over

NJ 8,095,542 1,680,818 1,106,028

PA 12,002,329 2,358,803 1,905,327

DE 744,066 150,327 96,809

MD 5,130,072 1,083,642 591,273


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The American Lung Association’sRecommended Key Steps

Implement the clean air standards for trucks and buses and fuels – completely and on time.

Adopt strong equivalent standards for all nonroad diesel equipment.

Close the loophole for diesel electric generators.

Implement retrofit programs now.


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Conclusion

Approximately one in ten Americans has a chronic

lung disease and is at risk from air pollution. Infants,

children, and the elderly are at increased risk, too.

These are not faceless statistics, but people close to you:

Your friends, your coworkers. Your parents, your children.

Your aunt with emphysema struggling to breathe.

Your coworker who can't make it in for that important task.

Your child taking that frightening trip to the emergency room.

Maybe even yourself.


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Remember:

When You Can’t Breathe, Nothing Else Matters.


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Additional Materials

(Not part of presentation, but for use in responding to questions, if necessary)


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Factors Affecting Composition of Diesel Emissions Engine types (light-duty to heavy-duty as

they appear in passenger vehicles to

off-road vehicles, in locomotives to

electric generators) Engine operating conditions

(idle, accelerate, decelerate) Fuel formulations

(e.g., sulfur or aromatic content)


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Factors Affecting Fate of Diesel Emissions Dilution Chemical & physical changes

Example: Diesel exhaust “aging” results in secondary PM formed from gas phase components

Transport Weather (sunlight, temperature,

humidity, precipitation) Other (interacting) pollutants Interactions with ground-level

environment


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Example of Study from Current Research

Study in April 3, 2002 issue of Immunotherapy Weekly presented at annual meeting of the American Academy of Allergy, Asthma and Immunology (AAAAI).

Prior evidence showed that Diesel Exhaust Particulate (DEP ) could increase immune system response and airway inflammation associated with various allergens.

This study examined hospital emergency room visits and inpatient admissions between 1995 to 2000. Asthma exacerbations for children under 18 years old increased 1.4 times in the fall compared with the spring, significantly correlated with higher levels of DEP.


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Reproductive and Developmental Effects Some possibilities in animal

studies Neurobehavioral and

neurophysiological effects in

neonatal rodents Organ systems not yet evaluated


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Immunological Effects Several observed effects in

immune system biochemical

mediators, inflammation,

cytological changes Diesel exhaust as potentiator for

known allergens Insufficient data to determine

reference level


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Genotoxic Effects of Diesel Particulates or Extracts

Mutagenic in several mammalian cell systems Aberrations in chromosomes or cell division Free radical inhibition of antioxidant enzymes Separately, substances in diesel exhaust have

been identified as genotoxic Questions remain about the level of

bioavailability


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Lifetime lung cancer risks per microgram of diesel exhaust:

Cancer risk per microgram of diesel exhaust particulate per cubic meter of air: Scenarios range on the order of 100 to 1000 per million population after 70 years

of exposure.


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Major Report on Particulate Air Pollution:March 6, 2002 of JAMA “Lung Cancer, Cardiopulmonary Mortality, and

Long-term Exposure to Fine Particulate Air Pollution” by Pope, C. A., et al.

Prospective mortality study of 500,000 adults in 156 cities, followed over the years 1982-98.

Conclusion: “Each 10-µg/m3 elevation in fine particulate air pollution was associated with approximately a 4%, 6%, and 8% increased risk of all-cause, cardiopulmonary, and lung cancer mortality, respectively.”


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Important Public Health News from Last Year Dec. 21, 2000: EPA issues rule for

diesel fuel and heavy duty diesel vehicles.

Feb. 28, 2001: EPA agrees to enforce rule.

May 3, 2002: Ruling by U. S. Circuit Court of Appeals for the District of Columbia Circuit upholds the rule.


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Important Public Health News from Last Year Rule to take effect in 2007. EPA estimates that annually the rule will

prevent 8,300 premature deaths, more than 9,500 hospitalizations, 5,500 cases of chronic bronchitis, 17,600 cases of acute bronchitis in children, 360,000 fewer asthma attacks, and more than 1.5 million lost workdays. The rule also will prevent cancers from diesel exhaust, which EPA has found to be a likely carcinogen in humans.


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References

… where you can find links to this same information – and more:

The 1998 California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment (OEHHA) Report www.arb.ca.gov/regact/diesltac/diesltac.htm

The 2000 US EPA Review Draft www.epa.gov/ncea/dieslexh.htm


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References

The 1998 & 2001 Natural Resources Defense Council Reports www.nrdc.org/air/transportation/

The 2001 OEHHA and American Lung Association of California’s Fact Sheet

www.californialung.org/downloads/diesel010501/ALA-OEHHA_diesel.pdf

Documents

May 30, 2003 American Lung Association of Pennsylvania 1 Health Effects of Diesel Exhaust Kevin M. Stewart Director of Environmental Health American Lung