Endocrine disruptors, invisible chemicals that trigger diseases health and wellbeing

“Spanish children pee in plastic,” says doctor and researcher Nicolas Olea provocatively. He doesn’t exaggerate. Nor is he wrong when he warns of the presence of perfluorinated chemicals, very persistent chemicals, in the blood or breast milk of an entire nation. Olea clearly demonstrates the widespread exposure of humans to so-called endocrine disruptors, compounds capable of imitating the body’s natural hormones and affecting health. These chemicals, which are invisible to the human eye but present in the environment and everyday products, can interfere with the endocrine system before birth and lead to reproductive health and various diseases such as cancer, diabetes, obesity or attention deficit hyperactivity disorder. Can affect development. , among others. For example, recent research suggests that early exposure to certain disruptive elements may trigger premature onset of puberty.

Human exposure to these chemicals concerns the scientific community. To begin with, because they are everywhere: in cosmetics, in personal hygiene products, in food packaging… and it is difficult to avoid them completely. “Research is very abundant in two aspects: into the mechanisms of how these pollutants interfere with hormonal receptors; and human exposure to these compounds. The evidence there is more than enough to intervene preventively,” warns Olea, who is professor at the University of Granada and doctor at the Clinical Hospital of the same city. Pesticides, heavy metals, bisphenol-A or parabens are some of the most well-known and studied disruptors.

If natural hormones are like a kind of messenger – substances that travel through the blood and bring an emitter into contact with a receiver, such as the ovary with the breast, then endocrine disruptors alter the entire network of communication. And mimic the role of natural molecules responsible for signaling and communication between cells and organs. These chemicals are able to interfere with any part of this communication process, whether for example, by altering the transport of hormones, blocking receptors or distorting the growth of hormone-producing cells. “They may interfere with the synthesis, transport or binding of the receptor and may reduce or enhance hormonal activity. Although the most common thing is to interfere with the receiver, they are like hacker Of that message (that hormones carry),” agrees Oliya.

Over 2,000 chemicals have been identified that have the potential to interfere with endocrine processes and alter health. But, perhaps, says the University of Granada researcher, these are only “the tip of the iceberg”. “The hormonal systems that have been studied are limited (estrogenic, androgenic, thyroid…). We suspect that the endocrine disruptors are related to vitamin D, which is actually a hormone. But we don’t know who they are that compete and intervene in that system,” reflects Olya, who is also a member of the Elementa thinktank and collaborator of the Rezero campaign, A Future Without Toxic Substances.

“We live in a chemical soup and we don’t have much of an idea of ​​what happens if you’re exposed to many different endocrine disruptors.”

Martine Vrijheid, Director of the Environment and Lifelong Health Program at ISGlobal

Martine Vrijheid, director of the Environment and Lifelong Health Program at ISGlobal, however, highlights good news amid this scenario that is so unfavorable for human health: “In general, the concentration of these substances” that are chemicals we find in the blood. The samples appear to be very small, although we need better information about the health effects of low-level exposure.

Among the endocrine disruptors that cause the most concern are polybrominated compounds, which are flame retardants and found in many synthetic and textile products. “They are usually caused by indoor exposure and are related to thyroid problems,” explains Oliya. Other chemicals in the spotlight are phthalates and phenols, which have also been linked to infertility in adults and stunted growth and ADHD in children.

Scientists are also concerned about perfluorinated compounds (known as PFAS), which repel water and oil and resist extreme temperatures. They’re concerned, says Vrijheid, because “not only are they endocrine disruptors, but they’re so-called forever chemicals: They are very persistent in the environment and body.” These chemicals can affect the immune system, cause liver toxicity or harm reproductive health, such as infertility. They are also linked to diabetes and obesity and Effects on the brain have been described, with effects on neurodevelopment, ISGlobal researchers list.

windows of vulnerability

Experts agree that measuring the effects of each chemical is complex because the dose-response relationship is not linear: there is not always a proportional relationship between the exposure dose and the magnitude of the effect. Furthermore, Olya recalls, “There’s a background within the body” and, although exposure to endocrine disruptors can occur at any time in life, there are windows of particular vulnerability.

The prenatal stage, when the fetus is in the process of forming, is one of those periods of sensitivity: These chemicals can cross the maternal placenta and interfere with the long-term health of the baby. For example, research published in the journal JAMA Pediatrics in 2018 found that prenatal exposure to various types of phthalates was associated with language delays in minors.

The prepubertal stage is also another window of particular sensitivity as this is the time when the body is ready to begin hormonal activity. In fact, a paradigmatic phenomenon partly linked to exposure to endocrine disruptors is the rapid earlier onset of puberty. The research was recently published in the journal endocrinology, For example, there are arguments that ambrette musk, which is a common fragrance ingredient of soaps, detergents and creams and other synthetic nitromusks, “may contribute to a tendency towards earlier puberty.” “Although our in vitro and in vivo data do not provide direct evidence supporting an effect on puberty, they represent the first step toward linking musk ambrette to neuroproductive axis activity during development. This possibility deserves further study,” the authors say.

Scientific results are limited, but this is not the first time a similar hypothesis has been raised. Anders Juul, pediatric endocrinologist and clinical professor at the University of Copenhagen, said: The LancetThat increased fat mass, as well as exposure to endocrine disruptors, may lead to a “worrying trend toward earlier puberty”. They added, “Environmental chemicals with hormone-like activities may promote premature activation of the pituitary-gonadal hormonal axis, leading to pubertal development, and/or may directly stimulate the mammary gland with estrogenic or antiandrogenic activity.” Can work.” However, a recent meta-analysis, Jules, failed to demonstrate a clear association between age at puberty and exposure to any individual chemical.

chemical combination

To refine the impact of these disruptions, more research is needed, with all voices being consulted. And it is also necessary, Vrijheid emphasizes, to investigate more deeply the effects of combining these chemicals. “There are many studies on endocrine disruptors, but most of them focus on a single chemical or perhaps a few chemicals from the same group. There are very few studies that show what happens if you have low exposure to many of these chemicals. “We live in this chemical soup and we don’t have much of an idea of ​​what happens if you’re exposed to many different endocrine disruptors.” A study published last May showed that exposure to a mixture of this type of hormone blockers is associated with poor metabolic health and contributes to an increase in metabolic syndrome (obesity, diabetes, hypertension …) throughout life.

Experts also regret the lack of information and clear guidelines for citizens. “Maybe we can provide better advice about what products they can avoid to reduce risk. But this is difficult because we do not have good information about which chemicals are used in which products. We need better labeling,” defends Vrijheid. Individual measures can be taken, such as reducing intake of processed or canned products, thoroughly cleaning interiors from dust or not heating food in plastic lunch boxes in the microwave; But a scientific review last year concluded that “policies to reduce or eliminate endocrine disruptors in manufacturing and processing in many areas, rather than individual behavior change, may have the greatest impact on population risk.”

However, the industry’s momentum does not help stem the rise of new disruptors. “When one chemical product is banned, it is replaced by 10 new products, and it is very difficult to keep track of it,” the researcher lamented. Industry moves faster than science and regulators are the slowest actors, says Oliya. And he gives an example: “In 1995 we first published that the coating of canned food contained bisphenol A. And he didn’t retire from bottles until 2011. And it will not be banned from the EU until 31 December 2024. It takes a lot of time to take decisions.”