Women and Chemicals

Why women?
verse this trend. Numerous factors contribute to diseases like
breast cancer, including inherited breast cancer susceptibility
genes. But these genes – which confer a 60-80 per cent lifetime
probability of breast cancer – are thought to underlie fewer
than 10 per cent of breast cancer cases. 9 Moreover, the susceptibility
genes do not cause breast cancer – they increase the
vulnerability of women to carcinogens and other factors that
promote breast cancer. A study of women with high-risk BRCA1
and BRCA2 genetic variations showed that 24 per cent of women
born before 1940 were diagnosed with breast cancer by age
50, compared with 67 per cent of women born later, indicating
that non-genetic influences do affect women at high genetic
risk. 10 There is substantial evidence linking a number of pesticides
and industrial chemicals to breast cancer risk. 11
Biological determinants
We are all continually exposed to hazardous chemicals in our
everyday lives. Once they have made their way into the air we
breathe, the water we drink, and the food we eat, it is only a matter
of time before they end up in our bodies. That harmful chemicals
make their way into the human body has been proven
through human biomonitoring, i.e. measuring toxic substances
in the body. Many toxins can be identified in samples of blood,
the umbilical cord, the placenta, breast milk, urine, hair, sperm
and fatty tissue. 12,13 So far 350 pollutants have been proven so far
to end up in the human body. 14
Women and men often have different exposure routes. For
example the US Center for Disease Control and Prevention (CDC)
reported that adult women have higher levels of urinary metabolites
than men for those phthalates that are used in soaps, body
washes, shampoos, cosmetics, and similar personal care products,
which are linked to e.g. birth defects. 15
Even more alarming is the fact that the human body burden of
chemicals is passed on from one generation to the next, with levels
of certain hazardous chemicals increasing from mother to child. 16
Susceptible windows of development
Women, men and children are all susceptible and exposed to
chemicals in different ways. In the case of women, biological
factors such as the difference in physical make-up, such as
more fatty tissue, are one reason for the different susceptibility
to chemicals. Both men and women experience ‘windows
of susceptibility’ during which the impacts of chemical exposures
can have critical effects on development and disease
burden, most notably during the perinatal period and puberty,
but women experience additional windows of susceptibility
during pregnancy, lactation and menopause. These
are periods when the female body changes and becomes
more vulnerable to influences from the environment. In the
following chapters some of these windows of susceptibility
will be addressed in more detail.
Trans-generational effects
There is emerging evidence that certain diseases triggered by
chemicals can manifest in later generations. When women are
exposed to a certain substance during their pregnancy, it can
be their children and grandchildren that face the disease. There
are animal studies showing that exposure to pesticides, phthalates,
dioxin, and nicotine can have this trans-generational effect
manifesting in low sperm counts, respiratory problems,
and obesity in later generations. 17,18,19 One of the most prominent
cases proving multigenerational effects is the continued
tragedy of diethylstilbestrol (DES).
Studies show that daughters of women who took the drug
during their pregnancy, as they were said that it would reduce the
risk of pregnancy complications and losses, developed a rare type
of vaginal cancer in a very young age, which was not normally
observed in women under 50. 20 They also suffered from other reproductive
tract abnormalities, decreased fertility, increased breast
cancer risk, and early menopause. 21 Even the granddaughters of
women who took the drug DES have a higher incidence of menstrual
irregularities and potential infertility. 22 The scientists at the
Women’s Reproductive Health and the Environment Workshop,
held in January 2008 at Commonweal, a health and environmental
research institute in the US, concluded that DES taught us three
important lessons that can guide our investigations of other
chemicals. The exposure to hormone disruptors during foetal development
can induce reproductive tract defects or other health
impacts in the foetus, even if exposure does not affect the mother’s
health. The risk of health impacts from exposure to hormone
disruptors is especially high during prenatal development. And a
disease induced during development might only be apparent
decades later, and exposure to this one chemical could lead to
multiple health risks. Girls who were exposed to DES prenatally
appeared to develop normally. Only in adulthood did health impacts
like uterine malformations, infertility, vaginal cancer, and
breast cancer become apparent. 23
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