American Association for Cancer Research  [Printer-friendly version]
June 1, 2005

ENVIRONMENTAL EXPOSURE TO TRAFFIC PAHS AND RISK OF BREAST CANCER

Peter Rogerson, Dominica Vito, Paola Muti, Maurizio Trevisan and Jo

[Rachel's introduction: A study links breast cancer to pollutants
from automobile traffic, specifically polycyclic aromatic
hydrocarbons (PAHs).]

By Jing Nie, Jan Beyea, Matthew Bonner, Daikwon Han, John Vena,

Peter Rogerson, Dominica Vito, Paola Muti, Maurizio Trevisan and Jo
Freudenheim

Polycyclic aromatic hydrocarbons (PAHs) are an important component of
air pollution and potential human carcinogens. While they have been
shown to cause mammary cancer in animal studies, the association
between PAH exposure and breast cancer risk is not well understood.

Traffic emissions are one of the major sources of PAH exposure in
cities. Further, growing evidence suggests that there may be critical
time periods of exposure in breast cancer initiation and development.

In this study, we examined the association between breast cancer risk
and exposure to PAHs from traffic emissions estimated for each woman
at menarche, at the time when she had her first pregnancy and birth,
and at 20 and 10 years prior to interview, using data collected from
the Western New York Exposures and Breast Cancer (WEB) study, a
population based case control study in western New York.

All participants were women, aged 35-79, residents of Erie and Niagara
Counties. Cases had incident, primary, histologically-confirmed breast
cancer. Controls were randomly selected and frequency-matched to cases
on age, race and county. In-person interviews were used to collect
data on potential breast cancer risk factors including self-reported
lifetime residential history. Traffic volumes on roads were obtained
from historical records for the years from 1960-2002. Tailpipe
emission data were based on previous reports, including measurements
carried out in tunnels or on individual vehicles run in place on test
beds.

A geographic model, developed by Dr. Beyea and colleagues from the
Long Island Breast Cancer project, was used to reconstruct historical
traffic PAHs, using BaP as a surrogate for total PAH exposure. Cruise
emissions, cold engine emissions and intersection emissions were used
to estimate total traffic PAH emissions.

Meteorological information was also utilized in the geographic
dispersion model to assign PAH exposure at each residence. The model
was validated using data collected from both Long Island and our study
area.

We found evidence that higher exposure to traffic PAH emissions at
menarche was associated with increased risk of premenopausal breast
cancer (OR 2.07, 95% CI 0.91-4.72, p for trend 0.03) and emissions at
the time of a woman's first birth was associated with postmenopausal
breast cancer (OR 2.58, 95% CI 1.15-5.83, p for trend 0.19).

Both associations were limited to lifetime non-smokers. There was no
association of traffic emissions with risk for any of the other time
periods.

These findings provide evidence for both the potential importance of
early exposures and the potential importance of an environmental agent
in risk of breast cancer.

Copyright 2005 by the American Association for Cancer Research.