Environmental Health - Endocrine disrupters






Most living animals, including human beings, have an endocrine system. The endocrine system—made up of glands such as the pituitary gland and thyroid gland—functions by releasing hormones into the bloodstream. Hormones are like packets of information, which are sent to different cells to stimulate specific reactions or processes that help to keep the body functioning properly. Some man-made chemicals look and act like these naturally-occurring hormones. These chemicals are called endocrine disrupters because, when they get into the bloodstream of a person or animal, they can prevent the real hormones from doing their jobs. Endocrine disrupters are synthetic chemicals or chemical byproducts. They are fat-soluble, which means they dissolve in fat, not water, and therefore remain in the body longer. Most endocrine disrupters come from pesticides or industrial chemicals.

WHAT DOES THE ENDOCRINE SYSTEM DO?

Body functions affected by the endocrine system in humans are:

body growth; organ development; metabolism; kidney function; body temperature; calcium regulation; blood pressure; reproductive cycles.

In addition to the above list, the following are also affected just in animals:

mating behaviors; migration; fat distribution; hibernation

What Endocrine Disrupters Do

Endocrine disrupters usually interfere with real hormones in one of three ways. They can be mimics, blocks, or triggers. Mimics imitate real hormones. The mere presence of these chemical imposters disturbs the body's delicate hormonal balance. When this balance is off, the body does not function properly. Blocks are endocrine disrupters that actually get in the way of real hormones. Hormones have to attach to a certain part of a cell, called a receptor site, to tell the cell what it needs to do to keep a particular organ or process running smoothly. Endocrine disrupters can block this information by attaching to a receptor site so that the real hormone cannot. With the endocrine disrupter in the way, the information the cell needs to function does not get through. Triggers do not just imitate or block real hormones; these endocrine disrupters actually give the body directions about what it should do. When the body responds to these signals, things go wrong because, unlike the real hormones, the endocrine disrupters do not know what they should be telling the body to do. The artificial triggers cause inappropriate growth, changes in metabolism, or other abnormal interactions that can create biological chaos.

Where Endocrine Disrupters Come From?

A wide range of synthetic chemicals and chemical byproducts developed for commercial and industrial purposes are suspected of being, or producing, endocrine disrupters. Many detergents, pesticides, plastics, and varnishes, for example, are made with or from endocrine disrupter chemicals. Through production and use of these products, endocrine disrupters are released into the environment where they can pollute food and water sources. Later, these artificial, hormone-disrupting substances can get into the bloodstreams of the people or animals who consume food and water from the contaminated sources.

Endocrine disrupters do not just come from environmental pollution. They can also be contained in synthetic drugs and be absorbed into a person's bloodstream when the drug is taken.

Most Common Endocrine Disrupters

The most common endocrine disrupters are known as environmental estrogens. Examples include PCBs and Dioxin. Environmental estrogens mimic the natural estrogens (female sex hormones) and androgens (male sex hormones), which control reproduction and sexual characteristics. Environmental estrogens have their biggest impact on fetuses (infants developing in a mother's womb). Once a baby is born, their sexual features are developed, but in the womb the sex hormones play a key role in shaping an infant's sexual makeup. The presence of artificial hormones in the mother's body can interfere with, or alter, the normal course of a fetus's sexual development.

Environmental estrogens have a particularly dramatic effect on males. Exposure to environmental estrogens in the womb can lead to a male being born with an unnatural amount of female sexual characteristics, or even a hermaphroditic condition, which is when a person has both male and female sexual features.

Sexual characteristics are not the only element that environmental estrogens can affect. Other biological features—such as bones, cardiovascular system, memory, and immune system—can be weakened in a male or female baby who is exposed to environmental estrogens in the womb.

Dead egrets on the shore of Lake Erie. (Photograph by Robert J. Huffman. Field Mark Publications. Reproduced by permission.)
Dead egrets on the shore of Lake Erie. (Photograph by
Robert J. Huffman. Field Mark Publications
. Reproduced by permission.)

DOCUMENTED EFFECTS OF ENDOCRINE DISRUPTERS

Polluted Species from the Great Lakes

The Great Lakes area is known to be a highly contaminated area, with particularly elevated levels of endocrine disrupters. Studies done on species from the Great Lakes area have revealed a range of abnormalities, such as the following:

  • Low rates of egg production, abnormal enlargement of the thyroid gland, early mortality rates, and low reproduction rates have been seen in several fish species, especially salmon.
  • Birds in the area (including bald eagles and herring gulls) that feed on these fish have demonstrated symptoms similar to those observed in the fish.
  • Hermaphroditic fish (genetically male fish with female genitals) have been observed.

The Florida Everglades

A study of male alligators was conducted in Lake Apopka, Florida, which is situated near a nowclosed chemical processing plant. DDE, a byproduct of the pesticide DDT, was generated at this plant. The male alligators in this area were found to have abnormally small penises, while male alligators in other (nonpolluted) Florida regions had normal size genitalia. Scientists attribute the Lake Apopka alligators' condition to exposure to DDE.

DES

A prescription drug called diethylstilbestrol (DES) was produced in the 1940s. The drug, which contained a synthetic estrogen compound, was administered to women who experienced complications during their pregnancies. It was later discovered to cause problems in the daughters of the women. The daughters who had had fetal exposure to the drug had depression, decreased fertility, abnormal pregnancies, organ dysfunction, and increased occurrences of cancers, especially of reproductive organs.

The Risks Associated with Endocrine Disrupters

Many studies conducted on animal populations in chemically contaminated areas strongly suggest that endocrine disrupters are potent and frequent pollutants of our food and water sources. Abnormalities, particularly sexual

Microwaving food in Styrofoam or plastic containers may allow plastics in the container to leach into the food being reheated. It is best to heat foods on microwave-safe dishware. (Photograph by Robert J. Huffman. Field Mark Publications. Reproduced by permission.)
Microwaving food in Styrofoam or plastic containers may allow plastics in the container to leach into the food being reheated. It is best to heat foods on microwave-safe dishware. (Photograph by
Robert J. Huffman. Field Mark Publications
. Reproduced by permission.)

abnormalities, have been observed in the offspring of the animals that live, feed, and drink in these contaminated areas. Although similar studies have not been undertaken in human populations, many scientists are concerned that the risks of human exposure to endocrine disrupters might be significant.

Pesticides can get into food supplies directly or indirectly. They can be sprayed on crops, which people later consume. Industrial pollution releases endocrine disrupters into the environment, exposing fish, cattle, hogs, and poultry. If the fish and animals ingest the chemicals, they will be contained in their fat and later passed on to human consumers.

Scientists have also expressed concern about plastics and artificial materials used in food preparation and storage. They are concerned that a leaching process might take place. Leaching is when dangerous products found in plastics move from the plastics into the food in the container. Although it is in the early stages, recent research has shown that endocrine disrupters can leach out of plastic containers into the liquid they are holding. Similar concerns have been raised about tin cans. Research suggests that the coating a tin can is treated with might contain endocrine disrupter chemicals, which are able to leach into the can's contents.

A sampling of common foods made with pesticide-free, organically-grown ingredients. (Photograph by Robert J. Huffman. Field Mark Publications. Reproduced by permission.)
A sampling of common foods made with pesticide-free, organically-grown ingredients. (Photograph by
Robert J. Huffman. Field Mark Publications
. Reproduced by permission.)

Incinerators and other equipment that use combustion release endocrine disrupters into the atmosphere. Once released into the atmosphere, they pose a risk to human life and wildlife.

Drinking water sources must also be monitored carefully. Contaminated drinking water could also expose humans to endocrine disrupters.

The effects of exposure to endocrine disrupters are not always immediate. It may take awhile for symptoms to surface, or the effects and problems could show up in the next generation (meaning in the children of the person who was exposed).

What Can Be Done to Protect Against Endocrine Disrupters

The scientific community is pursuing research in the area of endocrine disrupters. Environmental groups like the World Wildlife Foundation are encouraging the government to crack down on industry's use of chemicals that are proven (or suspected) to be endocrine disrupters. And more testing needs to be done to determine other chemicals that are endocrine disrupters. While investigation and regulation of endocrine disrupters is taking place on a national scale, people can protect and educate themselves on an individual level, too. Some suggestions for limiting exposure to endocrine disrupters are to:

THE BLACK PLAGUE

Environmental health has been an issue since ancient times. Even in the earliest days of civilization, it became clear that infections could be produced and spread in certain environments. Bubonic plague, nicknamed "the Black Plague," which claimed 25 million lives in Europe from 1347 to 1532, is an example of an infectious disease made worse by environmental conditions. Unsanitary living conditions gave the fleas and rats that carried the disease access to homes, bedding, and food. As people realized how important the proper management of drinking water, food supplies, and sewage was, new methods were developed to combat contamination and pollution. In modern society, health problems are now more commonly thought to be lifestyle-related, rather than correlated to environmental causes. But health risks from the environment can be substantial even in a sophisticated, technologically advanced society. In fact, many of the modern processes and products themselves are responsible for creating a whole new range of environmental risks to be explored and controlled.

  • limit fat and oil intake (since endocrine disrupters tend to accumulate in fats)
  • avoid cooking, microwaving, and storing food in plastic or styrofoam containers
  • use pesticide-free, organically-grown foods
  • not handle pesticides
  • investigate the origin of fish, poultry, and meat by asking the grocery store manager what the source is
  • encourage local store owners and managers to purchase produce and animal-based products from waters, farms, and rangelands that have been tested for pollution and contamination
  • get involved in antipollution efforts in your community
  • write to state legislators to find out their views on key statewide environmental issues


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