What We Know about Endocrine Disruptors and Men’s Health
Shop We spend a lot of time at goop researching and asking questions about specific toxic ingredients that exist in our personal-care products, our water, and our food supply. Of particular concern are endocrine disruptors, chemicals that interfere with the functioning of hormones in the body that studies have shown are related to myriad health consequences, such as reduced sperm quality, obesity, infertility, developmental disorders, and birth defects.
We talked to Dr. John Meeker, an epidemiologist and professor of environmental health sciences at the University of Michigan School of Public Health, who has spent his career researching how chemicals in our environment impact human health and specifically the endocrine system. Meeker shares tips for reducing exposure to endocrine disruptors—like pesticides in our food and phthalates in our shampoo—and reminds us that this is only part of the picture. We need more research and regulations to better protect our health, the health of future generations, and the health of our planet.
A Q&A with Dr. John Meeker, ScD, CIH
Researchers have reported trends that show male sperm concentration and testosterone levels as well as other measures of male reproductive health have been declining over the past few decades. When you compare today’s data to the 1950s or so, a fifty-year-old man today might have the testosterone level that a seventy-year-old would have had several decades ago. These sorts of trends are driving a real concern that the way we use and are being exposed to chemicals, like endocrine disruptors, might be having serious impacts on our health.
The term “endocrine disruptor” is broadening all the time. Early on, it was thought to be something that could interfere with an estrogen receptor. We now know that there are all kinds of reactions that could result in a chemical not only binding to or blocking the receptor, but also possibly altering which hormones are produced, transported, and metabolized. If any of these processes are impacted by a chemical, that chemical is called an endocrine disruptor.
“There’s a large and growing list of chemicals that are thought to be endocrine-disrupting compounds.”
There’s a large and growing list of chemicals that are thought to be endocrine-disrupting compounds. Some of them have been around forever, like some metals. But when we talk about endocrine disruptors, we’re usually talking about synthetic or man-made chemicals.
After World War II, certain chemicals became popular and were used widely for various applications, such as insecticides and herbicides. But it turned out that these chemicals were very persistent in the environment and had adverse effects on wildlife. And then as researchers started to look into impacts on humans, it turned out that these chemicals also had a range of toxic effects on the endocrine system, affecting reproduction. Some of these chemicals include polychlorinated biphenyls (also known as PCBs), DDT compounds that were used for mosquito control (and still are in some parts of the world), and other synthetic pesticides. Many of these chemicals have since been phased out in most of the world but still persist environmentally in soil and other places.
More contemporary endocrine-disrupting chemicals include nonpersistent pesticides, such as organophosphates and pyrethroids. There are also PFAS chemicals, which are very persistent environmentally and were used in the production of nonstick cookware and a range of consumer products until very recently. Phthalates are another group of endocrine disruptors; they are used as plasticizers to make products containing PVC more flexible and are also used as solvents in personal-care products, such as lotions and perfume. Other endocrine-disrupting chemicals, such as triclosan and parabens, are used as antimicrobials in lotions, shaving creams, hair products, toothpastes, and many other products. These types of chemicals have gotten a lot of attention in the last decade, but this list encompasses a much larger and growing number of chemicals. Luckily, phthalates and antimicrobials tend to be less persistent in the environment.
There are a lot of possible ways to be exposed, depending on the chemical. Nonpersistent pesticides are found in conventionally grown foods. Because persistent pesticides and other pollutants, like PCBs, are lipophilic (meaning they dissolve in fat) and remain in the environment, exposure can also come from consumption of animal products, like meat, fish, and dairy.
Food packaging is another source of exposure. Historically, a lot of canned goods have been lined with bisphenol A, which was a major source of exposure. In recent years, a lot of companies have stopped using BPA, labeling their products “BPA-free.” But in many cases, they may be replacing BPA with bisphenol F and bisphenol S, which are both very similar to BPA. BPF and BPS are not exactly the same as BPA, but they may have a lot of the same toxicological properties and potentially similar health effects.
“In recent years, a lot of companies have stopped using BPA, labeling their products ‘BPA-free.’ But in many cases, they may be replacing BPA with bisphenol F and bisphenol S, which are both very similar to BPA.”
Exposure to phthalates has shifted in the past ten or twenty years. Nowadays, diet is a big source of exposure for high-molecular-weight phthalates from plastic food packaging and food handling equipment that contains phthalates. Phthalates used to be found primarily in consumer products, such as building materials, flexible PVC, and even children’s toys. We’ve since learned that some of these phthalates, such as diethylhexyl phthalate, are reproductive toxicants. So now, DEHP and a few other phthalates are starting to be removed from these products and are banned in children’s products. What’s concerning is that companies are replacing those phthalates with other phthalates or new replacement chemicals that have similar properties but are less studied from a toxicological perspective. We don’t know yet if these new chemicals will have similar health effects as the phthalates that have been more thoroughly studied.
Parabens are often used in personal-care products as antimicrobials. Parabens are classified as pesticides in the United States, so they have to be disclosed on the label of any product they’re in, whereas phthalates do not. People can be exposed by using lotions or fragrances that have these ingredients in them.
Then there’s occupational exposure, which often combines large magnitudes of exposure to these chemicals over long periods of time. Any job that deals with pesticide applications—such as agricultural workers, exterminators, or greenhouse workers—will have large exposures. Industrially, there are manufacturing jobs that use a lot of these chemicals in large volumes, which could put workers at risk if adequate exposure control measures are not in place.
In the early days of research, much of the research was heavily geared toward male exposure to chemicals in occupational settings. In recent years, there have been many studies of cohorts of pregnant women and children looking at their exposure and health outcomes. For example, a pregnant mother is exposed to endocrine disruptors through cosmetics, food, or other products she uses, and researchers look at measures of male reproductive tract development in the boys born in those studies. Those impacts could last throughout puberty and potentially, when those boys try to have children later in life, there could be lasting effects there as well with regard to their fertility.
The research with men has primarily looked into levels of hormones, like testosterone, as well as sperm quality (concentration, motility, morphology, and DNA damage) because they are fairly simple measures to study that can be assessed in a short time frame. There are also studies that look into long-term consequences, such as testicular cancer, which are more difficult to study due to the potential for a long latency period between exposure to the chemicals and disease onset. Other studies have looked at fertility more indirectly by assessing time to pregnancy among couples who are unable to get pregnant. But it’s difficult to know whether it’s the male or female (or both) who is primarily affected because male and female infertility are equally likely. Newer studies, in the past few years, have begun to use innovative study designs that consider both partners and have also started looking into epigenetic modifications in the sperm cells that might impart effects to a person’s future children later in life.
There needs to be more research on male exposure to endocrine disruptors and other sensitive health end points, such as their impacts on metabolism, obesity, and the mechanisms through which they act—for example, whether these chemicals can directly damage cells or if they work more indirectly by impacting testosterone levels or other aspects of endocrine function.
Pesticides have to be registered with the Environmental Protection Agency. To do that, there needs to be a whole battery of toxicological tests, including cell studies, in vitro tests, and animal studies to assess acute, subchronic, and chronic effects of exposure. However, no human studies are required. And sometimes animals in lab studies don’t respond to exposure the same way a human might, so that’s where there is often a large gap in the regulation.
Use chemicals sparingly and only when you need them, whether it’s a personal-care product or a lawn-care product or a cleaning product. Overuse can lead to a lot of unnecessary exposure.
Check the labels on your products and try to avoid products that have endocrine-disrupting chemicals, such as phthalates or parabens. Keep in mind that fragrances, including perfumes and colognes, don’t need to disclose if they have phthalates in them, and even if you are taking measures to reduce phthalate exposure, some degree of that exposure may be unavoidable because of how widely used fragrances are.
Buy organic produce when possible, to decrease your exposure to pesticides. Studies have shown that people can reduce their exposure to endocrine disruptors by buying organic.
Buy less packaged and processed food. In general, the more packaging and processing involved, the greater the amount of endocrine-disrupting chemicals that may have been introduced into the food.
At the policy level, more action is needed. Even with individuals taking measures to try to reduce their exposure, it’s not possible to completely avoid these chemicals. There is a wide range in a person’s ability to take steps necessary to reduce exposure (e.g., higher cost of organic or less processed foods, or living near an agricultural field that is treated with pesticides). National policies that limit or prohibit the production and use of chemicals that are found to adversely impact health are a critical approach to reducing exposure—and the associated health risks—at the population level.
John Meeker, ScD, CIH, is an epidemiologist and a professor of environmental health sciences and global public health at the University of Michigan School of Public Health, where he also serves as the senior associate dean for research. He has published extensive research on human exposure to environmental contaminants such as endocrine disruptors.
This article is for informational purposes only, even if and regardless of whether it features the advice of physicians and medical practitioners. This article is not, nor is it intended to be, a substitute for professional medical advice, diagnosis, or treatment and should never be relied upon for specific medical advice. The views expressed in this article are the views of the expert and do not necessarily represent the views of goop.