Childhood Asthma/Tobacco Smoke

Introduction

Characteristics

Fate and Transport

Exposure Pathway

Methods for Monitoring in the Environment

Methods for Measuring Human Exposure

Strategies for Preventing or Controlling Exposure


Respiratory Harmful Effects

Deposition, Absorption, and Metabolism

Dose-Response Relationship

Organ Sites of Toxicity

Biomarkers

Risk Assessment/Risk Management Considerations

References

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Risk Assessment/Risk Management Considerations

For complete reports, please refer to the following EPA publications:

1992 EPA Report: Respiratory Health Effects of Passive Smoking (Also Known As Exposure To Secondhand Smoke Or Environmental Tobacco Smoke - ETS)

1997 California EPA Office of Environmental Health Hazard Assessment (OEHHA) Report: Health Effects of Exposure to Environmental Tobacco Smoke

Risk Assessment of Respiratory Effects

Based on the existing human and animal data (please see ‘respiratory harmful effects of ETS on child respiratory system’ and ‘dose-response relationship of ETS and childhood respiratory effects’ for review), the EPA reports made the following risk assessment conclusions:

  • Infants and young children are especially sensitive to ETS. The 1992 EPA report states that ETS exposure in children is causally associated with:
    • increased risk of lower respiratory tract infections such as bronchitis and pneumonia (EPA estimates that 150,000 to 300,000 cases annually in infants and young children up to 18 months are attributable to ETS)
    • increased prevalence of symptoms of upper respiratory tract irritation (evidenced by cough, excess phlegm, and wheeze), and small reductions in lung function
    • additional episodes and increased severity of symptoms in children with asthma (EPA estimates that up to 1 million asthmatic children have their condition worsened by exposure to ETS)
    • The epidemiological studies on respiratory health effects reviewed in the CA EPA report (1997) support the previous finding by the U.S. EPA (1992) that there is “sufficient evidencethat passive smoking is causally associated with additional episodes and increased severity of asthma in children who already have the disease.”
  • Both reports concur there is compelling evidence that ETS exposure is a risk factor for the development of new cases of asthma

Scientific Approach of the Reports

  • The U.S. EPA conducted a “weight-of-evidence analysis” regarding the respiratory effects in children. They reviewed more than 100 studies, including 50 epidemiologic studies of children whose parents smoke.
  • The CA EPA conducted a meta-analysis in order to more thoroughly investigate the relationship between ETS exposure and childhood asthma. Sixty-eight epidemiologic studies were identified as potentially relevant (1975-1995), and after inclusion criteria were established, the final analysis was conducted on 37 studies. Risk ratios and standard errors were then extracted or calculated.
  • Both reports also covered a range of other health effects resulting from ETS exposure, including but not limited to, carcinogenicity, pulmonary disease, cardiovascular effects, otitis media, and developmental toxicity.

Risk Management

In response to the conclusions of these reports and the large body of research indicating ETS is a human lung carcinogen, several states have led the way in adopting state regulations as a part of a risk management response (i.e., California, New York City do not allow smoking in public places). However, for children, the single most important location for exposure to ETS is in the home. Please refer to strategies for preventing and controlling exposure for further information.

U.S. EPA “Fact Sheet: Respiratory Health Effects of Passive Smoking “, 1993
“Although EPA does not have any regulatory authority for controlling ETS, the Agency expects this report to be of value to other health professionals and policymakers in taking appropriate steps to minimize peoples' exposure to tobacco smoke in indoor environments.

In cooperation with other government agencies, EPA will continue its education and outreach program to inform the public and policy makers on what to do to reduce the health risks of ETS as well as other indoor air pollutants.”
The EPA website (http://www.epa.gov) has a plethora of information in the form of fact sheets, brochures, and other publications aimed at educating the public regarding the harmful effects of environmental tobacco smoke.

The California Scientific Panel concluded:
“After careful review of the February 1997 drafl of the OEHHA report, “Health Effects of Exposure to Environmental Tobacco Smoke,” we find the draft, with the changes specified by OEHHA in our June 19, 1997 meeting, as representing a complete and balanced assessment of current scientific understanding. Based on the available evidence we conclude ETS is a toxic air contaminant.”