A substantial body of scientific evidence indicates that
exposures to common chemicals and radiation, alone
and in combination, are contributing to the increase in
breast cancer incidence observed over the past several
decades. Key recurring themes in the growing scientific
literature on breast cancer and environmental risk factors
are: (a) the importance of understanding the
effects of mixtures and interactions between various
chemicals, radiation and other risk factors for the disease;
and (b) the increasing evidence that timing of
exposures matters, with exposures during early periods
of development being particularly critical to later risk
of developing breast cancer. A review of the scientific
literature shows several classes of environmental factors
have been implicated in an increased risk for breast
cancer, including hormones and endocrine-disrupting
compounds, organic chemicals and by-products of
industrial and vehicular combustion, and both ionizing
and non-ionizing radiation.