ENVIRONMENTAL EPIDEMIOLOGY (F LADEN AND J HART, SECTION EDITORS)
Air Pollution and Breast Cancer: a Review
Alexandra J. White
Patrick T. Bradshaw
Ghassan B. Hamra
Published online: 27 March 2018
This is a U.S. government work and its text is not subject to copyright protection in the United States; however, its text may be subject to foreign copyright
Purpose of Review Breast cancer is the most common cancer diagnosed among US women. Air pollution is a pervasive mixture
of chemicals containing carcinogenic compounds and chemicals with endocrine-disrupting properties. In the present review, we
examine the epidemiologic evidence regarding the association between air pollution measures and breast cancer risk.
Recent Findings We identified 17 studies evaluating the risk of breast cancer associated with air pollution. A higher risk of breast
cancer has been associated with nitrogen dioxide (NO
) and nitrogen oxide (NO
) levels, both of which are proxies for traffic
exposure. However, there is little evidence supporting a relationship for measures of traffic count or distance to nearest road, or
for measures of particulate matter (PM), except potentially for nickel and vanadium, which are components of PM
air toxic levels and sources of indoor air pollution may also contribute to breast cancer risk. There is little existing evidence to
support that the relationship between air pollution and breast cancer risk varies by either menopausal status at diagnosis or
combined tumor hormone receptor subtype defined by the estrogen receptor (ER) and progesterone receptor (PR).
Summary Epidemiologic evidence to date suggests an association between breast cancer risk and NO
, markers for
traffic-related air pollution, although there was little evidence supporting associations for proxy measures of traffic exposure or
for PM. More research is needed to understand the role of specific PM components and whether associations vary by tumor
receptor subtype and menopausal status at diagnosis.
Keywords Air pollution
Polycyclic aromatic hydrocarbons
Breast cancer is the most common cancer diagnosed among
women in the United States (USA) , and there is an interest
in better understanding the role of environmental factors on
breast cancer risk . Air pollution is an established environ-
mental risk factor for lung cancer , and outdoor air pollution
has been classified by the International Agency for Research
on Cancer (IARC) as a group 1 carcinogen .
Air pollution contains a mixture of many compounds, in-
cluding polycyclic aromatic hydrocarbons (PAHs), metals,
and benzene; these may act as carcinogens or as endocrine
disruptors and, thus, be relevant for breast carcinogenesis.
Inhaled toxicants have been measured in breast fluid, showing
that airborne pollutants can reach the breast tissue . The
most well-studied compounds are PAHs , a combustion
by-product, which has the capacity to bind to DNA and form
adducts in the breast tissue . Both PAHs and metals have
estrogenic properties [8, 9], produce oxidative stress , and
induce mammary tumors in animal models [7, 9]. Particulate
matter, a complex mixture of small airborne particles includ-
ing metals and hydrocarbons , has been shown to exhibit
estrogenic properties and DNA-damaging activity in vitro
, and benzene induces mammary tumors in rodents .
Both indoor and outdoor air pollution have been associated
with breast tumor methylation of candidate genes selected a
priori based on their relationship with breast cancer .
Breast cancer risk has been shown to be elevated in urban
areas where air pollution is higher [15–17], and ecologic stud-
ies suggest that increasing traffic emissions in the USA has
been associated with an increase in breast cancer risk [18, 19].
This article is part of the Topical Collection on Environmental
* Alexandra J. White
Epidemiology Branch, National Institute of Environmental Health
Sciences, NIH, Research Triangle Park, NC 27709-2233, USA
Division of Epidemiology and Biostatistics, School of Public Health,
University of California Berkeley, Berkeley, CA, USA
Department of Epidemiology, Johns Hopkins Bloomberg School of
Public Health, Baltimore, MD, USA
Current Epidemiology Reports (2018) 5:92–100