Nicolás Olea: “Take as much plastic out of the kitchen as you can, ventilate and prioritize eating well over other things”

For nearly four decades, physician and researcher Nicolás Olea (Granada, 1954) has studied how thousands of chemical compounds present in plastics, cosmetics, or packaging interfere with the hormonal system and may contribute to the development of various diseases. He was one of the pioneer researchers to study the effects of bisphenol A on human health and today he is an international reference in the field of endocrine disruptors. With humor, vehemence, and a contagious passion, Olea, author of 80 recomendaciones para evitar los tóxicos (Integral, 2025), maintains that regulation lags decades behind scientific evidence and offers a series of practical recommendations to reduce daily exposure to these substances, which he considers, for the most part, avoidable.

Why should we be concerned about endocrine disruptors?

— Because they interfere with our hormones. We know that there are hundreds of thousands of chemical compounds manufactured by humans and that about 2,000 have hormonal activity. They compete with our hormones and can alter processes as important as sexual development, fertility, thyroid function, or the brain. What is difficult is to prove that a single one of these substances is the cause of a specific disease, because we are talking about multifactorial diseases. It would be nonsense, totally false, to say that bisphenol A is the sole cause of breast cancer. But we do have enough scientific evidence to state that exposure must be reduced, because it does indeed have an impact on health.

When did you start studying this phenomenon?

— I am a doctor. I spent three years researching breast cancer in Belgium and in 1987 I went to Boston as a researcher at Tufts University, with 350 serum samples from prostate cancer patients. I carried them in typical laboratory vials with orange caps, disposable, with a conical bottom. I wanted to analyze their antiandrogenic hormonal activity, but for three months all the samples came out extraordinarily estrogenic. At the laboratory, they thought I had contaminated them and were about to fire me. We took one of the tubes to the Massachusetts Institute of Technology (MIT) for them to analyze it. It was made of modified polystyrene and the manufacturer had added an antioxidant so the plastic would not turn yellow over time. That antioxidant had contaminated all the samples and we discovered that it had estrogenic activity.

That discovery changed the way of understanding plastics.

— It was the beginning. That same year, researchers in California published two papers in which they detected estrogenic activity in yeast cultures. In the end, they verified that it did not come from the yeast, but from the water heated in polycarbonate bottles that contained bisphenol A and that they used to prepare the food for the yeast. Suddenly we understood that compounds like bisphenol A or nonylphenol could act as hormones. And that opened Pandora's box, because these chemical products were everywhere, even in baby bottles.

Is it then that the concept of endocrine disruptor appears?

— In 1992 we met with Theo Colborn, a pioneering American environmental researcher,who had collected a huge amount of evidence on hormonal alterations in wildlife: alligators in Lake Apopka, intersex fish, aquatic birds, mollusks... She threw a very simple question at us: "If all this is happening to animals, do we really think that nothing is happening to humans?" That question changed the way of looking at this problem. The concept of endocrine disruption was coined by her in 1992 and, since then, the scientific literature in this field has not stopped growing. Today there is no longer a debate about whether there are substances capable of altering the hormonal system, but rather the discussion focuses on to what extent this exposure contributes to the diseases that we see more and more frequently.

Which diseases does it refer to?

— We are seeing an increase in fertility problems. Thyroid disorders, precocious puberty, some neurodevelopmental disorders, and various hormone-dependent tumors, such as breast cancer, have also skyrocketed. I am not saying that endocrine disruptors are the only cause of all this. What I am saying is that they constitute a modifiable risk factor. If you have a nine-year-old girl, why should you expose her to bisphenol A if you have alternatives?

Why are these products not prohibited if there is evidence that they are harmful to health?

— This is the big problem. The regulations governing chemical products remain very permissive. Classical toxicology still does not adequately incorporate hormonal effects nor the chemical cocktail effect: every day we ingest dozens of chemical residues, each within legal limits, but what happens when all these compounds act at once is not evaluated.

Why is it so hard to regulate them?

— Because there are enormous economic interests. The industry exerts very intense pressure on European institutions. Even so, the European Chemicals Agency, ECHA, has taken important steps. For the first time, substances are being regulated by taking into account their activity as endocrine disruptors and not just whether they are carcinogenic, mutagenic, or toxic to reproduction. They have already taken on perfluorinated compounds, PFAS, and have recognized the so-called "regrettable substitutions": when bisphenol A is banned, the industry reacts by replacing it with bisphenol F or bisphenol S, which end up presenting similar problems. It makes no sense to go about banning molecule by molecule; it is necessary to regulate the entire family, which is what ECHA proposes.

It has taken three decades to ban bisphenol A in many uses.

— Exactly. We detected bisphenol A in the inner lining of canned food containers in the mid-nineties. Thirty years have passed until Europe has definitively restricted many of its food uses. Thirty years. In Spain, the ban took place on December 31, 2025. This is the pace of regulation. The inevitable question that arises is who bears the cost of this delay? Who pays for fertility treatments? Who pays for developmental problems? Who pays for cancers? Will anyone take responsibility for it?

Why do endocrine disruptors especially affect women?

— There is a biological part and a social part. Women have a much more complex hormonal physiology: the menstrual cycle, pregnancy, menopause... All this makes them more sensitive to any hormonal interference. If you look at many diseases related to the endocrine system, the difference is enormous. Hypothyroidism affects approximately nine women for every man. In multiple chemical sensitivity, the proportion is even greater, fifteen women for every man. In addition, there are social factors. A woman continues to be more exposed to cleaning products and, above all, to cosmetics. It is estimated that a woman uses an average of fourteen cosmetic products every day, each one with dozens of ingredients, which translates into hundreds of chemical components applied daily to the skin. You can forget to take your blood pressure medication, but you will hardly stop wearing deodorant. The good news is that Europe is eliminating some of these compounds: triclosan has practically disappeared from mouthwashes and toothpastes. Various PFAS and some ultraviolet filters like benzophenone-3, present in sunscreens, are also being restricted.

While the regulation does not arrive, what can we do?

— Reduce exposure to it. The first place I would start is the kitchen. Get rid of as much plastic as you can. Go back to wood for cutting, glass for heating food, and stainless steel. Do not heat food in plastic containers in the microwave. Avoid plastic lunch boxes. Many of the things our mothers and grandmothers had worked better than the materials we have incorporated later. It is also advisable to reduce excessively packaged foods. Today we go to the supermarket and practically everything is wrapped in plastic.

What should we put in the shopping cart?

— Healthy eating and sustainable eating should go together. Buy seasonal and local products whenever you can. Stop eating kiwis from New Zealand that have traveled 22,000 km to relieve your constipation. The ecological footprint of this fruit is insurmountable. Do not give your children Pescanova fish sticks, because they were caught in 2022 in Namibia and have been frozen at -38 degrees for at least three years. It would be cheaper for a local to bring you the fish on a motorcycle! Go to the market, and see what they have brought today, whether it's anchovies, sardines, local hake, or squid. Buy fresh, seasonal, local products. If you can, organic. It is better for your health and also for the environment.

Not everyone can afford it.

— The shopping basket today accounts for 13% of family budgets, while in the 60s it was 60%. What has happened since then? That we spend our money on other things. If the key to health is nutrition, start setting priorities. Reduce mortgages, phone bills, Netflix, clothing, and commit to eating well. If you buy a liter of milk for 50 cents, they are either cheating you, or the producer, or the cow; it is clear that someone ends up getting burned. Start choosing with a bit of judgment, pay a fair price for food. Let's stop keeping producers stifled!

He is very critical of intensive livestock farming.

— Because the model is unsustainable. We produce a huge amount of meat, especially pork, intended largely for export. I always make the same joke: with the millions of pigs that are in Spain, 31 million, you should see them crossing the train tracks when you go from Granada to Barcelona. But you don't see them because they are concentrated in intensive farms. We consume too much meat. It is not necessary to eliminate it completely, but yes to reduce its consumption and bet on higher quality products.

It also warns about clothing.

— The textile industry is another source of exposure. Many fabrics incorporate compounds so that they repel water, do not wrinkle, or resist stains. All of these are chemical additives. I recommend always washing clothes before wearing them for the first time, especially children's clothing. Choose natural fibers whenever possible and extend the useful life of the garments. The best waste is that which is not generated. Second-hand shops, for example, have an unexpected advantage: after many washes, the clothing has already lost a good part of the compounds it carried when it was new. Furthermore, you extend the cycle of each piece of clothing. And when there is no other choice, recycle.

What can we do at home to reduce exposure to toxins?

— Ventilating is probably the most effective measure and also the cheapest. Household dust accumulates synthetic fibers, perfumes, flame retardants, and many other chemical compounds. Instead of sweeping, it is better to vacuum. And one must be wary of the marketing that has made us believe that a clean house is a house that smells of perfume. No, a clean house is a ventilated house.

If you had to summarize your message in one sentence, what would it be?

— Change your home environment. Remove plastic from the kitchen, buy fresh food, ventilate, wash clothes before wearing them for the first time, and consume less. You won't do it all at once, but every step reduces exposure. Your health is at stake, and so is that of your children.