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Endocrine
Disrupting Chemicals in Pesticides and Plastics
Over the
last ten years, clinical and ecological research continues to suggest
that many chemicals, both synthetic and natural, have the ability to
disrupt the hormone balance of the endocrine system, producing
various negative effects in all sorts of creatures, including birds,
fish, wildlife, and even human beings.
When
discussing the hormonal implication of these chemicals, scientists
and researchers have labeled these chemicals endocrine
disruptors. In today's 21st century world, these
products are everywhere in our lives. Some of the most common places
where these chemicals exist are pesticides, cosmetics, toys, foods,
flame retardants, detergents, metal food cans, and some plastic
bottles.
Today,
there is a limited body of scientific data available regarding these
chemicals, but there is a legitimate concern over how these chemicals
may have an impact on human health. In the environment, there are
areas which are polluted with endocrine disrupting chemicals to an
extent that ecological populations are experiencing deleterious
effects directly as a result. These negative health impacts have also
been proven in a laboratory atmosphere.
Although
it is clear that Endocrine Disrupting Chemicals are a health risk
under certain circumstances and concentrations, it can be hard to
study the health impact of these chemicals, because people are
generally exposed to a number of these chemicals at varying
concentrations at the same time. There are government and non-profit
organizations dedicated to clarifying the health risks and
implications associated with Endocrine Disruptors, two of which are
the National Toxicology Program and the National Institute of
Environmental Health Science.
These
groups support and fund scientific studies aimed at fostering a more
complete understanding regarding how these chemicals impact hormone
balance in an effort to protect both human beings and wildlife from
the negative impact of Endocrine Disrupting Chemicals. In the near
and distant future, these programs hope to minimize the domestic and
global environmental and health impact of these chemicals and to
discover ways to mitigate the negative effects.
What
is an Endocrine Disrupting Chemical?
Endocrine
Disrupting Chemicals are synthetic or naturally occurring chemicals
which have the capacity to interfere with the secretion or functional
capacity of hormones produced by the endocrine system. These
chemicals have the ability to significantly alter hormone balance in
both humans and animals, leading directly to negative health
consequences. A number of these Endocrine Disruptors have been
strongly correlated with immune, neural, reproductive, and
developmental issues in both captive and wild animal populations.
Many
researchers also believe that these chemicals and compounds also have
the ability to negatively impact human health at existing
concentrations. There is some correlation between reduced fertility
and Endocrine Disrupting Chemicals. These chemicals also appear to
increase the risks of certain health conditions, including several
cancers.
In
addition to Endocrine Disruptors and Endocrine Disrupting Chemicals,
these chemicals are also referred to by a number of other names,
including Endocrine Active Compounds, Environmental Hormones, and
Endocrine Modulators.
There are
forms of chemical pollution that affect various types of hormone
balance, but the group of chemicals that have received the largest
body of scientific study are those that increase the physiological
influence of Estrogen. A number of other chemical disruptors have
been identified however, including those that encourage the
production of thyroid hormones, androgens, and progesterone, and
those that inhibit the production of Estrogens and Androgens.
What is
the Importance of the Endocrine System?
Along with
the Neurological System, the Endocrine system is the primary way that
the body communicates changes from disparate areas of the body. The
Endocrine System also plays a central role in the coordination and
control of numerous physiological functions. The Endocrine System
produces these changes directly through the secretion of hormones
from Endocrine Tissues situated throughout the body, including the
pancreas, thyroid, pituitary, testes, and ovaries. These hormones
then enter the blood stream where they flow to target organs and
affect change.
Hormones
are able to conduct the complex orchestra of necessary functions
which keep us happy and healthy. One example of how hormones function
is the complex way that the reproductive system, nervous system, fat,
liver, gut, and kidneys work together in order to control and
maintain various metabolic functions, including:
Endocrine
Disrupting Chemicals interfere with the normally-closed set of
signals flowing throughout the body to keep us healthy, leading
directly to hormone imbalance which causes a variety of negative
consequences.
How do
Endocrine Disrupting Chemicals Work?
Animal
research has provided us with a lot of insight regarding the impact
of Endocrine Disrupting Chemicals. There are a number of different
mechanisms through which EDCs have the ability to alter the normal
function of the human body.
Endocrine
Disruptors have the ability to:
Substitute partially or completely for hormones produced naturally by the human body, such as Thyroids Hormones, Androgens, and Estrogens. These chemicals imbalance the system by overstimulating the body with the effects of a particular hormone. Block the normal and healthy function of a hormone by blocking cell receptors and preventing hormones from making their connections. In these cases, the target organ does not receive the full physiological signal, and the body displays symptoms and signs of deficiency. Chemicals that produce these effects are categorized under terms such as Anti-Androgens and Anti-Estrogens. Other Endocrine Disruptors actually have the ability to block or alter the way that hormones and hormone receptors are controlled or created. One example is that there are certain EDCs which can prevent the proper metabolism of hormones by the liver.
What
are Some Particular Examples of Endocrine Disrupting Chemicals?
There are
a large number of chemicals which have the capacity to alter normal
Endocrine Function in a variety of ways. A few well known Endocrine
Disrupting chemicals are, PCBs, Dioxin, and the medication
Diethylstibesterol (also known as DES), and pesticides like DDT .
There are
other chemicals, commonly plasticizers and pesticides, which have
been shown to have Endocrine Disrupting effects in animal studies,
such as Bisphenol A (also known as BPA). Bisphenol A is a synthetic
chemical that is in many plastic products such as bottles, which
leach from certain products when exposed to heat. BPA has many
industrial applications, including the creation of beverage and food
containers, and well as an ingredient of resins used in dental
sealants.
Another
large group of Endocrine Disrupting Chemicals are known as
phthalates. The industrial application of these synthetic chemicals
is to improve the flexibility or soften plastics made from polyvinyl
chloride. One common phthalate is DEHP. This chemical is used in the
production of a large number of polyvinyl products such as food
packages, clothes, car products, building materials, children's
products, and medical tools. Scientists with the National Toxicology
Program have found that there may be a link between DEHP and
developmental issues in young children, especially male infants which
are seriously ill.
Some of
the most common forms of naturally occurring Endocrine Disrupting
Chemicals are known as Phytoestrogens. These chemicals are naturally
produced in some plants, and have the ability to partially mimic the
effects of Estrogen under some circumstances. Some of these chemicals
can be found in foods and other products produced from soy, such as
daidzein and genestein.
Representatives
of the National Toxicology Program recognized the importance of
evaluating the risks of Endocrine Disrupting Chemicals upon human
reproduction, and created The Center for the Evaluation of Risks to
Human Reproduction. This group analyzes various products for signs
that they may impact normal fetal and childhood development. The
Center has determined that seven Phthalate compounds have
Endocrine-Disrupting Effects, as well as one particular Phytoestrogen
known as Genistein. Genistein is an ingredient in infant formulas
derived from soy.
How do
People become Exposed to Endocrine Disrupting Chemicals?
There are
a number of ways that individuals of all ages can become exposed to
EDCs. It can enter through their dietary choices, the medicines they
are prescribed, and even the make-up they put on their face. Exposure
can occur directly through the skin, through the digestive system,
and through breathing.
Many
chemicals which have these Endocrine Disrupting qualities take a long
time to degrade or otherwise dissipate, such as the pesticide DDT.
For this reason, many EDC Chemicals can be a health risk for long
after they are initially used.
What is
the Current State of Endocrine Disrupting Chemical Research?
The
National Institute of Environmental Health Science has spent over
thirty years researching the impact of medical Diethylstilbestrol on
human patients. This chemical was used from the 1940s to the 1970s
because medical professionals mistakenly believed that the chemical
had the ability to reduce the risk of miscarriage for patients at
serious risk.
In 1972,
it was discovered that daughters born to mothers that were treated
with DES had a significantly increased risk of experiencing a very
uncommon form of vaginal cancer. In addition to this, DES produced
many other changes in children of both sexes born to mothers that
took the drug. The National Institute of Environmental Health Science
performed extensive animal studies which proved the link between
exposure to DES and the development of birth defects and increased
cancer risk.
Leading
directly from this initial, stunning series of discoveries,
scientists with the NIEHS have continued to study other chemicals
which interact adversely with estrogen receptors. Scientists continue
to broaden the body of knowledge regarding Endocrine Disrupting
Chemicals in a number of different ways, including:
Creating new tools and models to reveal new information about how Endocrine Disruptors function Uncovering new techniques to discover which chemicals produce Endocrine Disrupting Effects Studying the impact of EDC exposure throughout the lifespan, and how it impacts health Studying the effects of EDCs in existing human patient populations Creating new tests and biological markers in order to measure both toxicity level and exposure to these chemicals Animal studies created to assess the effects of EDC exposure Developing ways to treat patients exposed to EDCs or learn ways to prevent exposure
When
are Endocrine Disrupting Chemicals Most Dangerous?
Scientific
studies show that EDC exposure produces the highest level of risk
before a child is born, or in the period after birth in which the
organs of the child's body are still developing. In animal studies,
there are a number of different issues related to early EDC exposure,
including increased cancer risk and reduced fertility, which may not
become an issue until a much later point in the lifespan.
In one
case, researchers found that animal subjects which were exposed to
synthetic BPA or natural, human Estradiol during prenatal development
as well as Estradiol during adulthood were much more likely to
develop a particular prostate cancer precursor. This study provides
evidence that both natural and synthetic estrogen exposure have the
ability to impact the way that the prostate behaves at the genetic
level, which increases the risk of prostate disorders and cancer.
Low
Level Endocrine Disrupting Chemical Disruptor Exposure
Researchers
have found that there is credible evidence that EDCs can impact the
physiological function of animals even at very low doses. These doses
are significantly below what has traditionally been believed to
impact health and physiology.
Even
though there has been a limited amount of study in regard to the
direct impact of EDCs upon human health and function, the body of
animal evidence is quite large, and Endocrine Disrupting Chemicals
have the ability to cause the following issues in animal populations:
Abnormal development of male reproductive organs Drop in male fertility Increased female-to-male birth ratio Increased incidence of sexual issues in female animals, including fertility complications and premature puberty Increased incidence of breast, prostate, and ovarian cancer BPA may also negatively impact diabetes and obesity.
Can
Endocrine Disruptors in Pesticides and Plastics Affect Future
Generations?
Evidence
suggests that Endocrine Disrupting Chemicals not only have a negative
impact on individual exposure, but EDC exposure may have a hereditary
risk as well. There is some research that provides evidence that a
patient exposed to Endocrine Disruptors may pass on their genetic
abnormalities to future generations. In laboratory animals, the
increased risk of cancer passed on three generations after initial
exposure.
Another
study found that male laboratory rats exposed to two particular EDCs
were found to carry on abnormalities to almost every male in
proceeding generations. The researchers hypothesize that these EDCs
have the ability to alter gene expression without directly causing
genetic mutation.
EDC
research is a vastly expanding field, and as our knowledge of the
effects of these chemicals continues to grow, it will help us to
prevent or mitigate the effects of these chemicals on both human and
animal populations.
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