What Are Endocrine Disruptors?
By Roberta Attanasio
According to the International Programme on Chemical Safety, World Health Organization (WHO) (2002), an endocrine disruptor is an exogenous substance or mixture that alters function(s) of the endocrine system and consequently causes adverse health effects in an intact organism, or its progeny, or (sub) populations.
This year, a group of experts convened by the United Nations Environment Programme (UNEP) and WHO defined the growing impact of hormone disruptors on human health problems a “global threat“.
What is the endocrine system? The endocrine system is one of the communication systems of our body and is found in all mammals, birds, fish, and many other types of living organisms. It’s made up of glands, which are located throughout the body and produce hormones. The major glands are the pineal, pituitary, thyroid and adrenal glands, as well as pancreas, ovaries and testes.
What are hormones? Hormones are chemical messengers that broadcast messages throughout the body. Radio broadcasting stations use radio receivers to reproduce the audio sound signals. Similarly, endocrine messengers must be received through specialized receivers to transmit signals – these specialized receivers are called receptors.
Therefore, in order to respond to a hormone, a cell must bear a receptor specific for that hormone. By interacting with a receptor in or on a cell, the hormone transmits a signal that tells the cell to behave differently – for example to grow more, or to stop growing.
Hormones and the signals they transmit are critical to the normal functioning of every tissue and organ in both vertebrates and invertebrates and are often quite similar across species. There are over 50 different hormones and hormone-related molecules that, from conception through adulthood and into old age, coordinate and regulate all biological processes in the body, including the development and function of the brain and nervous system, the growth and function of the reproductive system, the development and function of the immune system, as well as metabolism and blood sugar levels.
What are endocrine disruptors? Endocrine disruptors (also called endocrine disrupting chemicals) are chemicals that interfere in some way with hormone action and in so doing alter endocrine function and cause adverse effects on the health of humans and animals.
Hormones and endocrine disruptors can act at all times during life – fetal development, infancy, early childhood, puberty, adulthood and old age. However, the strength of their impact may be different depending on the timing of their action.
For example, during adult life the effects of hormones or endocrine disruptors may occur only during exposure. When exposure ends, the effects decrease.
What is developmental programming? Because hormones play an important role in the development of tissues and organs during fetal life, infancy and/or early childhood, exposure to endocrine disruptors during this time may cause permanent effects. This process is called developmental programming and leads to increased susceptibility to diseases later in life.
Some endocrine disruptors produce transgenerational effects – effects that can cross generations. Exposure of a pregnant woman or a pregnant animal may affect not only the development of her offspring but also their offspring over several generations.
What are examples of endocrine disruptors? One well-known example of endocrine disruptors is diethylstilbestrol (DES), a synthetic estrogen. Prior to its ban in the early 1970’s, DES was prescribed to millions of pregnant women to block spontaneous abortion and promote fetal growth. It was later discovered, after the children went through puberty, that DES affects the development of the reproductive system and causes vaginal cancer.
An additional example of endocrine disruptors is bisphenol A (BPA). BPA is a chemical used mostly as a monomer in the production of polycarbonate plastic and epoxy resins. Polycarbonate is widely used in tableware, microwave ovenware, food containers, water bottles, milk and beverage bottles, and water pipes. Epoxy resins are used as protective linings for a variety of canned foods and beverages. Therefore, exposure to BPA occurs primarily through the diet and it has been linked to developmental toxicity for fetuses, infants and children (effects on the brain, behavior and prostate gland). Exposure to BPA has been also linked to the development of obesity, In addition, results from a recent study show that BPA may act as a complete mammary gland carcinogen.
This article shows that sometimes it’s almost second nature to come in contact with these harmful chemicals such as drinking from plastic bottles or even warming up food using plastic containers in the microwave. These actions may seem normal and part of the daily grind but cause adverse health problems in the future.
According to the Health and Environment’s presentation “Hormone Disruptors and Women’s Health”, approximately 85% of 80,000 chemicals in the environment have been flagged as health threatening. In addition to the chemicals mentioned in this article, others include Phthalates, found in various fragrances and cosmetics, and cigarette smoke. These chemicals can cause early puberty, infertility and cancer in both men and women miscarriages in women.
One such hormone, Growth hormone (GH) plays a key part in production and proliferation of antibodies. GH stimulates cell growth and has been linked to stimulating T-cells, which are cells of the adaptive immune system that produce chemokines and cytokines, proteins that assist in signaling the immune cells towards the site of infection amongst other actions. In the case where GH is disrupted, it can cause these a reduction of these immune cells, causing one to be more susceptible to infection. With this in mind amongst other warning signs, one needs to consider both the short-term and long-term effect of their actions.
To: Lorna GM
The points you suggest on growth hormones playing an important role in the production and proliferation of antibodies is a fascinating fact that I did not know. It is important to understand how growth hormones may affect the T-cells especially when focusing on how the immune system responds to foreign antigens. Without the proper antibodies the immune system can be affected by infections and ultimately in the worst case possible, be inadequate.
Fascinated by Lorna GM’s post, I researched growth hormones and other effects it may have on the immune system. In an article by S. Smaniotto et. al called “Growth hormone stimulates the selective trafficking of thymic CD4+CD8- emigrants to peripheral lymphoid organs,” highlights the importance of growth hormone stimulating CD4+CD8- (T-helper) cells on lymphoid organs which is similar to Lorna GM’s post on helper T-cells activating B-cells to become plasma cells and overall secrete antibodies.
Interesting concept, Lorena.
It surprises me how many potential cancer inducing chemicals are present in items that we viewed as common things. I really can’t imagine the stress and work that our immune system have to endure in order to keep us from becoming ill. According to the Breast Cancer Fund, approximately 5 million tons of endocrine disruptions were produced in 2008 and over 500 tons of BPA is released into the environment annually (http://www.breastcancerfund.org/clear-science/radiation-chemicals-and-breast-cancer/bisphenol-a.html) And since BPA is present in various items and eating utensils, it can drain into our food easily if heated.
Studies have shown that BPA causes massive proliferation of splenocytes. This is very alarming because over stimulating a cell to proliferate can certainly leads to mutations and cause cancer. Another concern is that BPA decreases the number of CD4 cells in the body, which can render the host’s immune system helpless and negatively impact antibody production. This would make the host more susceptible to infections, especially to extracelluar pathogens. And because CD4 cells also activate cytotoxic T cells, the immune system ability to control potential cancerous cells that are caused by BPA is limited, which could lead to breast cancer in both women and men(http://www.sciencedirect.com/science/article/pii/S0161589012004142).I personally believe that cancer is becoming an common thing in our society because of the chemicals we used to preserve things like food, food containers, and air pollution.
Your comment on growth hormone is definitely interesting. It also made me think about the recombinant or artificial growth hormones that we take into our body. One example of such is the recombinant bovine growth hormone (rBGH) that is used by dairy farmers to increase milk production in milking cows. Although the FDA backs its usage, several companies have decided to stop selling products that contain rBGH. It’s just so interesting because many of the things that we introduce to our body are so new and we still lack the proper research to determine if these have harmful or beneficial effects.
This is true that cancer is becoming more and more common in our society because of these substances that are part of our everyday use, especially the ones in place for convenience. For instance I looked up the effects of Styrofoam in our system and I found out that especially when in contact with hot fluids, foods or fat, polystyrene, releases the chemical styrene, which is considered a neurotoxin. It so easy to pick up a plastic plate or cup in the name of “less dishes” but we really have to look at the bigger picture. Same case in rBGH. It is more beneficial for the farmers to use this hormone due to monetary profit but in the long run it may end up hurting us. It’s unfortunate. We really need to look at the bigger picture. http://www.bios.niu.edu/news_events/Dangers_of_Polystyrene.pdf
It’s so common now to hear that something has been called a “global threat”, we have so many! Of course, globalization is going to give us many more global threats. The problem with endocrine disruptors is not only they’re global, there are too many of them. I’m wondering if anyone has a list of all the endocrine disruptors, I bet there are thousands of them, probably most of the bad chemicals we breathe, touch and eat.
This article gives a very informative insight into endocrine disruptors and their effects on our body especially during fetal, infancy and childhood. It is sad to know how few people are aware of these endocrine disruptors and that they can be introduced into our body by consuming canned food such as bisphenol A (BPA). A research study done by Harvard School of Public Health describes the link between consuming canned soup with the greatly elevated levels of the chemical BPA. http://www.hsph.harvard.edu/news/press-releases/canned-soup-bpa/ . BPA was observed by collecting urine samples showing a elevated amounts of BPA. It would be of great benefit to do a study on animals to find the effects of consuming BPA by pregnant animal and their side effect on the fetus and infant progeny.
It is kind of scary to know how much BPA we might have absorbed in our system already. And how this BPA accumulation can lead to problems in the future. Especially for kids who regaularly have meals from cans, i am guessing over time as levels of BPA rise it could lead to some major health problems.
Littlesusie, I found this list of endocrine disruptors that a non-profit organization by the name of The Endocrine Disruption Exchange (TEDX)has compiled. TEDX tries to determine all the different sources of endocrine disruptors. This list sort of breaks them down alphabetically and then cites exactly when they were classified as a disruptor. http://www.endocrinedisruption.com/endocrine.TEDXList.overview.php. Hope that helps!
Sometimes it’s hard for the general public to understand the effects industrial chemicals (and some naturally occurring chemicals) may have on their body. This lack of interest is probably due to the fact sometimes the effect doesn’t immediately take place. I love the way that this article puts into perspective how endocrine disruptors may not cause noticeable damage immediately, but eventually could become the source of irreversible problems for future generations. It also allows one to become more aware of what they are putting into their body, and initiate the quest for more personal research when making everyday life choices. If you aren’t aware now, then you probably won’t remember the hundreds of BPA lined water bottles you used 10 years ago could be the reason for the cancer you have today!