Endocrine Disruptors: How They Affect Health

Endocrine disruptors are compounds that, as their name suggests, disrupt the endocrine function of our body. They mainly affect reproductive development and fetal growth.

Written and verified by el biólogo Samuel Antonio Sánchez Amador.

Last update: 16 January, 2023

The endocrine system is made up of a group of glands and organs that make hormones and release them directly into the blood. The compounds synthesized by this functional set regulate practically all the functions of the organism, including the rate of general development, tissue activity, metabolism, and the activity of the sexual organs. Because of this, endocrine disruptors are a serious threat to our health. Find out about them today.

The endocrine system is as intricate as it is exciting, but there are a number of conditions that can cause imbalance, ranging from mild to severe imbalance. Hypothyroidism, hyperthyroidism and diabetes are the best-known hormonal imbalances, although there are many more. Most of these disorders manifest themselves systemically, as hormones affect more than one organ at the same time.

Despite the extensive knowledge that we have acquired regarding hormonal imbalances, science doesn’t stop surprising us. Here we’ll bring you all the information you need to know about certain agents that interfere with our hormonal system: endocrine disruptors. Keep reading!

What are endocrine disruptors?

The National Cancer Institute (NCI) defines the endocrine system as “the set of glands and organs that make hormones and release them directly into the blood so that they can reach tissues and organs throughout the body.” Hormonal compounds are key to life and regulate the daily metabolism, and the development and reproduction of living beings.

The main hormonal secretion structures in the human body are the ovaries, testes, pancreas, adrenal glands, thyroid, parathyroids, pineal gland, hypothalamus, and pituitary. These are the primary organs responsible for keeping the endocrine system afloat, but the kidney, liver, heart, and other tissues act as secondary regulatory structures.

The functioning of hormones is very complex, however, it can be summarized in a couple of lines. The compounds are released into the extracellular space, spread into the circulatory system, travel in the blood, and reach their target tissues or cells, where they perform a specific task. The receptors (membrane and nuclear) are expressed in the cells that will be affected by the hormone in question.

Endocrine disruptors are compounds that, in one way or another, prevent the proper functioning of our hormonal circuit. The European Commission defines them as ‘exogenous substances or elements that alter the function or functions of the endocrine system and consequently cause adverse health effects in an intact organism, its progeny or (sub) populations’.

This definition isn’t only important in the human world, as it also includes the possible effects of the release of these compounds on ecosystems. Although we talk about health from an anthropic perspective, we mustn’t lose sight of the fact that the endocrine system is present in many animals. They are also affected by endocrine disruptors.

Characteristics of endocrine disruptors

Endocrine disruptors are numerous and have highly varied structures. However, its mechanism of action can be summarized in the following list:

1. Many of these compounds are capable of mimicking the biological activity of a hormone by binding to its cellular receptor. This can cause the stimulated cell to carry out an erroneous, poorly localized, or excessive response. It is called an agonistic effect.
2. Some endocrine disruptors bind to the receptor on the target cell, but don’t stimulate it. The adherence of the foreign compound to the hormone reception mechanism of the cell body will make the actual hormone unable to bind to it. From a functional point of view, the cell is inactivated. This is an antagonistic effect.
3. Other disruptors simply bind to transport proteins in the blood. This modifies the homeostasis of the blood plasma and increases the concentration of chemical compounds in this connective tissue.
4. Lastly, these compounds are also capable of modifying the synthesis and metabolism of hormones in the body. This causes an increase or decrease in the speed of natural metabolic processes, among many other things.

Some of these disruptors have been used for decades in human health, as indicated by the United States Environmental Protection Agency. Birth control pills are the clearest example of this, as their main function is to stop a woman’s natural ovulation. However, many other of these compounds are released into the environment and have very undesirable effects.

Types of endocrine disruptors

The typology of endocrine disruptors is based on their chemical nature. Human beings are exposed to them by consuming contaminated food, drinking water in contact with harmful chemicals, applying unregulated cosmetics, and using pesticides that have already been withdrawn from the market (or even some commercialized ones).

Although the harmful concentrations of many of the endocrine receptors haven’t been clarified, it’s suspected that very low amounts may affect the body. Hormones are very powerful metabolic agents, and these chemicals either mimic or inhibit them. Next, we’ll show you the most important examples with their specific routes of action in each situation. Don’t miss it!

1. Xenoestrogens

Xenoestrogens are chemical compounds that are part of a heterogeneous group of active hormonal agents. They can be both natural and synthesized by humans and their main purpose is to mimic the action of estrogen, the hormone responsible for the regulation and development of the female reproductive system and its secondary sexual characteristics.

Xenoestrogens are in the spotlight of the scientific community for their apparent correlation with various human (and animal) health problems, as they have the potential to disrupt the natural reproductive process. We’ll show you some specific examples within this group.

1.1 Alkylphenol

This compound represents a functional group of chemicals that are used as herbicides to make PVC and to synthesize modified polystyrene. As their name suggests, they’re obtained by alkylating phenolic compounds. As emphasized by the EPA, they’re potentially toxic, endure in the environment, and have the ability to bioaccumulate.

Sources of exposure to alkylphenols in the human environment include the following:

• Aquatic pollutants: These chemical compounds have been found in treated waters in some regions. It’s also common to find them in sewage sludge.
• Food contaminants: Containers that contain alkylphenols in their composition could accumulate (theoretically) in food. However, more research is required to verify this fact.
• Home and domestic environment: Alkylphenols are very common in household structures (for example, in the PVC of many pipes). Its concentration also seems to be related to the use of certain household products.

Professional documents show that alkylphenols don’t only have estrogenic effects, but are also toxic and even promote cancer in certain living beings. The bioaccumulation of these compounds in discharges and in the environment is a problem for fauna, but also for human health in the long term.

1.2 Bisphenol A (BPA)

BPA is one of the most common endocrine disruptors in general society, as it’s used in the production of polycarbonates, epoxy resins, some polysulfone, and other niche materials. Its effect is very similar to that of estrogen and for decades various governments have questioned the use of this compound. For this reason, more and more BPA-free plastics are being manufactured.

The Mayo Clinic is quite scathing when analyzing Bisphenol-A. This body cites several sources that claim that the compound leaks into foods and beverages that are kept in plastic containers with BPA. This has been associated with brain dysfunction in children and increased blood pressure, diabetes, and cardiovascular disease in adults.

1.3 Dichloro diphenyl trichloroethane (DDT)

Dichloro diphenyl trichloroethane, better known as DDT, is an organochlorine compound that is vital for the synthesis of pesticides. In the past, it was used primarily against the coleopteran pests that plagued American crops, but later its use also began in order to minimize mosquito populations (transmitters of malaria and other diseases).

This is one of the endocrine disruptors that are already banned when it comes to purchasing and use. All insecticide products containing DDT are banned globally (in the United States since 1969), because, in addition to its toxic effect, its analogy with estrogen interrupts the reproductive cycle of several animals.

We can go even further, as scientific sources have shown that DDT has negative effects on the human male reproductive system. Various tests on workers who were exposed to this substance showed that their reproductive health and the quality of their semen was much lower after being exposed to this insecticide for long periods of time.

2. Other possible endocrine disruptors

Xenoestrogens have been studied extensively, but it’s suspected that there are many more endocrine disruptors with similar or different functions to those of the compounds already mentioned. Here are some examples:

• Dioxins: These compounds are obtained from combustion processes that mainly involve chlorine. They bioaccumulate in the environment and increase in concentration as the level in the trophic chain increases. Dioxins are found in trace amounts in human food.
• Polycyclic aromatic hydrocarbons (PAH): These are located in natural sources, although they can also be obtained after incomplete combustion of organic matter. Tobacco smoke is the causative agent for 90% of indoor PAH levels in the homes of smokers.
• Phenolic compounds: Bisphenol A is in this group, but also many other chemicals (such as butylhydroxytoluene, nonylphenol, and picric acid).

Research on the effects of potential endocrine disruptors on the human body and other animals continues today. Experimental models (especially laboratory mice) are a great help in understanding their dynamics on a micro scale, but it’s also necessary to know how they affect the entire ecosystem.

Endocrine disruptors and human health

Although all the information presented seems alarming from a health point of view, it’s also essential to note that governments of the world are currently employing measures to prevent the use of endocrine disruptors in commonly used products. For example, in the United States, the Toxic Substances Control Act was passed in 1976 to ban many of them.

For its part, the European Commission has been identifying endocrine disruptors available on the market in thousands of products since 2013 (disinfectants, insecticides and cosmetics, above all) in order to permanently ban them.

What can you do to avoid the indirect consumption of endocrine disruptors? Unfortunately, there is no easy answer. Chemicals are found in our food and in the environment, but you can always choose a more reliable source when consuming food from extensive farms (not intensive ones) and by minimizing the use of plastic packaging.