Office of Environmental Health Hazard Assessment

Air Toxicology and Epidemiology

Memorandum: Environmental Tobacco Smoke as a Toxic Air Contaminant to Which Infants and Children May Be Especially Susceptible

Toxic Air Contaminant

Endpoints of Most Concern

Major Reasons Why Chosen


Respiratory Irritant

Exacerbation of asthma; modeling predictions indicate concentrations in urban air above cREL

Chlorinated dioxins and dibenzofurans (dioxins)

Developmental toxicity, immunotoxicity, endocrine disruption; thyroid effects

Widespread exposure; endocrine disruption, thyroid and immuno-toxicity at low body burden; young animals more susceptible than older animals

Environmental Tobacco Smoke

Developmental effects, including low birthweight and decrease in birthweight, Sudden Infant Death Syndrome, pre-term delivery.

Respiratory effects, including acute lower respiratory tract infections, asthma induction and exacerbation, Chronic respiratory symptoms, middle ear infections in children.


Widespread exposure; numerous adverse health effects; several known effects are specific to children, and other known effects to which infants and children may be more susceptible.

Lead and compounds

Developmental neurotoxicity/CNS effects

Children the most susceptible subpopulation due to developmental neurotoxicity.

Particulate Emissions from Diesel-fueled Engines (Diesel exhaust particulate matter)

Enhancement of allergic response; exacerbation of asthma; developmental effects, genotoxicity and lung cancer.

Enhancement of allergic response and implications for exacerbation and possible induction of asthma; Major source of ambient PAHs, PM10; exacerbation of asthma by PM10; PAH developmental toxicity and genotoxicity a concern.

Polycyclic Organic Matter (POM)

Developmental effects, genotoxicity and lung cancer

Animal studies indicate teratogenicity, and fetotoxicity; human studies indicate greater genotoxicity following in utero exposures.

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