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Fertility specialist Oluyemisi (Yemi) Famuyiwa discusses her article, “How timing affects chemical exposure risks.” Yemi introduces her fascinating concept of “chrono-exposomics,” explaining how the time of day you are exposed to environmental chemicals may be as important as the dose. She reveals how our body’s circadian rhythms (like liver detoxification and skin permeability) change over 24 hours, meaning the same exposure at 8 p.m. is not the same as at 8 a.m. Using the example of a manicure, Yemi explores how endocrine-disrupting chemicals (like phthalates and TPO) in nail products might be absorbed more heavily in the evening, posing a unique risk to fertility and hormonal health. Learn the practical, evidence-informed adjustments you can make to align your self-care routines with your body’s natural schedule.

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Transcript

Kevin Pho: Hi. Welcome to the show. Subscribe at KevinMD.com/podcast. Today, we welcome back Yemi Famuyiwa. She is a fertility specialist. In today’s KevinMD article is “How timing affects chemical exposure risks.” Yemi, welcome back to the show.

Yemi Famuyiwa: Thank you so much, Kevin. It is a pleasure.

Kevin Pho: All right. Tell us what your latest article is about.

Yemi Famuyiwa: My article is about looking at toxins and the effect on the reproductive axis. That is always one of the popular things that I like to dig into for my patients. I am always telling them about exposure, but then I took it a step further when I started reading other articles and I realized that the toxins can also be more potent or less potent depending on when the exposure occurs. That came from other studies that I was reading. When I read my articles, I started reading about the differences in exposure to certain things that have to do with timing. That is the origin of that story.

Kevin Pho: All right. When you talk about toxins, what exactly are we talking about?

Yemi Famuyiwa: We are talking about anything that is foreign to the body. It will be a xenobiotic. It is not manmade. So any chemicals, specifically chemicals that the human body is exposed to. We know that some of these toxins like phthalates and BPAs and this one that is more popular right now is TPO. They are not natural to your body. The body doesn’t know what to do with it.

We are talking about when your body comes into contact with this, either through what you do as a profession, what you put on your body to look pretty, or what you are exposed to in your everyday life. How is that assimilated into your cells? How does your body detoxify you? If it is not adequately removed or detoxified, what impact will it have on you, on your reproductive axis, and more? It has other effects body-wide.

Kevin Pho: So in your article you say that the body’s circadian rhythms change over 24 hours. So things like liver detoxification and skin permeability mean it affects when the exposure is. So like if you are exposed to a toxin, say at 8:00 p.m., it is different from being exposed at 8:00 a.m. Is that correct?

Yemi Famuyiwa: Right. A lot of that observation came from studies. They started in animals in the animal kingdom, and they noticed that the animals may metabolize certain things differently. For instance, if you look at insects (not that humans are insects), if you spray insecticides at a certain time of the night and day in their world, some of those sprays or chemicals are neutralized by the insects because their genes that metabolize them and break them down get revved up at a certain time of the day. So if you spray them at that time, well, you might as well just spray water because they have layered on super protection. Then at other times, that gene is downregulated and the insecticide is more effective.

Take that one step further. There was actually a study they did in Europe where they took a group of people. They had them go to the grocery store and buy the normal fruits that they normally eat in a day. You are told to eat four or five servings of fruits. So you buy the normal fruits that you normally buy. They said to buy from the same store because they wanted to eliminate variability. But the only difference was you can consume those fruits, say in the morning between 8:00 and 10:00 a.m., or wait till 7:00 to 10:00 p.m. to consume them. Then they measured the urinary metabolites of residues of six insecticides that were sprayed on the fruits to protect them from insects. They found out that the individuals that ate those fruits in the morning had very negligible insecticide residue in their system. The ones that consumed theirs between 7:00 and 10:00 p.m. had higher residues.

What is the difference? Just when they ate. Well, you take it one step further. When you look at pharmaceutical companies, they call it chronopharmacodynamics, if you will. So they will say: “Well, this medication, you need to take it in the morning. That medication, you need to take it in the evening.” Why did they do that? They are looking at when that medication can be absorbed and utilized best, and they plan it over time because your liver breaks down a lot of these chemicals. Your CYP proteins and your glutathione transferases: the gene that regulates that is upregulated during the day. In the evening when you are supposed to be resting, your liver is not going to crank out those genes. So there is less biometabolism of those chemicals in the evening. Does that make sense?

Kevin Pho: Yeah. So the rhythm that your body already has, when you plug on top of that your exposure, your exposure may be more potent at certain times of the day, especially with the reproductive system. Hormonal surges are vulnerable to the circadian rhythms, and then sometimes when you are exposed to these toxins can have these unique effects on these hormonal rhythms, right?

Yemi Famuyiwa: Correct. The most common one that most people may know about is like in Europe recently, they banned TPO. It is used to create gel for women when they do their gel fingernails. It helps the gel stick and last longer. It is not the only one; it is just one of the many that can be used in the gel. Gels have been shown to be carcinogenic, so it was banned in Europe. They didn’t ban gel per se. They just banned that key ingredient because they found it to be carcinogenic.

There are other studies that have looked at individuals who work in nail salons and then measured the exposure of some of these chemicals in these individuals. So nail salon workers sometimes, if they don’t protect themselves, tend to have higher residues of some of these chemicals. Also, some patients, if they freshly do their nails and they get tested, may have some of this residue.

Should you stop doing gel? Try to avoid the TPO that is in it, and you can ask if they have TPO in them. That is one thing. Number two, your skin is more permeable to absorbing chemicals later on during the day. You can measure skin permeability. So maybe that might make you change when you go get your nails done. Maybe you might want to get it earlier in the day. Or maybe you might ask if they have an air cleaner venting system so that most of these chemicals are vented away from you.

Knowing what to do is why I wrote that blog. Being aware of these chemicals and being aware that their effects may be more potent at different times of a day just gives you the power of choice. Then you have the conscious choice to make certain changes to protect yourself.

Kevin Pho: Is this advice that you share with patients? For people who are trying to get pregnant, if they decide to do their nails, you suggest that maybe they could do it earlier today because their skin is less permeable during that time?

Yemi Famuyiwa: Yeah, I do. I have started doing a lot of counseling for my patients. When I see a new patient, I run through all the chemical exposures they could go through. So most of my initial consultation is just sharing with them what could be affecting them. For instance, we know that some patients may have poor egg quality. Nowadays, I am seeing men with very bad sperm quality, so I try to run through with them things in their environment that are low-hanging fruits where you could try to make a change in your lifestyle. Will it translate directly into more births? I don’t know. But when you know something can affect your system and when you know it is a foreign tissue to the body anyway and it can get absorbed, then that is just a low-hanging fruit that you can try to make changes in.

Kevin Pho: So what other fertility-related advice do you give as it relates to timing of potential exposure to toxins?

Yemi Famuyiwa: I go into more detail than just chemicals. I think we had this in one of your episodes before. I do talk about the recent evidence that shows that microplastics are absorbed into the human placenta. They found it in sperm and in testicular tissue. So then I tell them: “Well, that’s easy. Try not to heat warm food out of plastic because when you do, you are eating some plastic with your food.” For hot beverages, use either glass or steel.

Then for my gentlemen, we do know also that heat has an effect on sperm. So try to avoid concentrated heat around your waist, especially if you know that you are going to be trying to conceive with your partner anytime soon.

Kevin Pho: Now, how about nail salon workers themselves? I am going to assume that many nail salon workers are women. What kind of advice do you have for them who work in a nail salon as it relates to their fertility?

Yemi Famuyiwa: Number one: Is the location well vented? Are they wearing a mask? Protect themselves if they have to be exposed to these chemicals. Do they wear protective skin gloves? Make sure their mask is on. Make sure their salon is well aerated and vented. If it is not, then maybe talk to whoever owns the salon and say: “Hey, listen, I heard this thing. Maybe we need to air this place out better.”

You can get air cleaners; during COVID-19, everybody bought those air cleaners. Most of them nowadays are almost medical grade. They have activated charcoal in there that can take volatile organic chemicals and clean it up. So for my patients that have to work in that environment, I think knowledge is power and doing just minor things to protect themselves helps.

Kevin Pho: As far as you know, are there any studies that kind of show the fertility rates as it relates to the timing and circadian rhythm of the exposure to potential toxins?

Yemi Famuyiwa: No, not timing. I have read a lot of articles with exposure and nail salon workers showing decreased fertility rates. I have read a lot about most of the studies right now being almost observational. The one I quoted you was a study where they just said: “Oh wow, we found that these chemicals lingered based on timing.”

Now it would be interesting to take it one step further. I would imagine that would be very expensive to do because you are talking about a population study to say we are going to have a thousand people who are exposed in the morning and then compare it to another thousand or more exposed in the evening. That would be interesting to see, but it has not been done yet. I would think that would be the next extrapolation.

Kevin Pho: We are talking to Yemi Famuyiwa, fertility specialist. Today’s KevinMD article is “How timing affects chemical exposure risks.” Yemi, let’s end with some take-home messages that you want to leave with the KevinMD audience.

Yemi Famuyiwa: Take-home message: Knowledge is power. If you can’t avoid it, maybe consider when you are exposed to certain things.

Kevin Pho: Yemi, again, thank you so much for sharing your perspective and insight. Thanks again for coming back on the show.

Yemi Famuyiwa: Thank you very much.