Today is International Women’s Day, so we took the opportunity to talk with a scientist in the field of chemicals and women’s reproductive health, Dr. Pauliina Damdimopoulou. She is Associate Professor in perinatal and reproductive toxicology and leads a research group on chemicals and female fertility at the Karolinska Institutet in Sweden.
Can you tell us a bit more about your work?
I focus on environmental exposures, like industrial chemical residues and air pollution, and their links to reduced fertility in women. I’m especially interested in the ovaries because they hold the precious, finite stock of oocytes – egg cells. All oocytes a woman will ever have form before she is born. This means that oocytes are among the longest living cells in the human body, and they potentially face decades of exposure to environmental pollution. My aim is to figure out how this exposure affects ovaries and oocytes and, thereby, the overall fertility in women.
What inspired you to start a career in this field?
Fertility was not an immediate choice for me. My background is in biochemistry and food chemistry, driven by a curiosity about how diet and its molecular components impact human health.
However, during my postdoctoral studies in France, things began to align. I worked with frog and fish eggs and observed how some females consistently produced better eggs than others. This was intriguing to me. Given the importance of reproduction to the species’ survival, why didn’t it work every time?
I wondered about the many chemicals in the environment. How might the modern environments, saturated with synthetic chemicals that didn’t exist a century ago, affect human oocytes and fertility? These questions catalysed my decision to pursue a second postdoctoral study focused on the biology of human eggs and embryos.
Once the chance to initiate my independent research emerged, I was ready to put all my interests together and establish a laboratory exploring the links between chemicals and female fertility in humans.
What impact do chemicals have on women’s reproductive health?
My research has shown that women are exposed to complex mixtures of environmental chemicals and air pollution particles, which we found both in the bloodstream and inside the ovaries, where the precious oocytes reside.
We have found significant associations between higher chemical exposure and a smaller reserve of oocytes. This reserve is essential for the reproductive lifespan. When the reserve of oocytes is gone, fertility is lost, and menopause starts.
We also found significant associations between higher chemical exposure and altered growth of the oocytes towards maturity, higher odds of infertility, and lower chances of success in infertility treatments.
These observations stem from cohorts of women living in Sweden and, like all epidemiological studies, only represent associations. To prove causation, my laboratory is now conducting controlled exposure studies in vitro to unravel the mechanisms and effects of chemicals in ovarian tissue exposure in a petri dish.
What are the trends that you are observing?
The general trends are consistent worldwide: total fertility rates are declining, and the average age of pregnant women is increasing.
On average, European women have their first child around 30 years old. Humans are one of the very few species where fertility ends in sterility midlife, marked as menopause around 45-55 years old, but fertility declines before this due to declining quality and quantity of the oocytes. In practice, this means that the “fertile window” is narrowing, leading to situations where some women may find it challenging to conceive when they begin trying at 30. Demand for infertility treatments is on the rise in Europe and elsewhere.
While the reasons behind these trends are undoubtedly multifaceted, my research indicates that environmental exposures may also be contributing factors.
How do harmful chemicals interact with the body to affect women’s reproductive health?
A lot of research is being conducted on endocrine-disrupting chemicals. These chemicals interfere with the body’s hormones, affecting hormone-sensitive processes such as reproduction. The effects may be more severe during sensitive windows of development, such as foetal life, when reproductive organs are forming.
However, developmental processes occur in reproductive organs in adults as well. For example, the uterine lining renews once a month – at the moment of menstruation, and immature oocytes continuously grow towards maturity within the ovaries. Thus, adults are also sensitive to those chemicals.
And endocrine disruption is likely to be just one of the many ways by which chemicals can affect our bodies. My current research focuses on mapping the molecular mechanisms by which chemicals affect ovaries.
What would you advise as the top 3 actions a woman can take to reduce the impact of chemicals on her reproductive health?
My number one advice is to vote for politicians who are willing to change the chemical regulations in Europe. Giving women long lists of dos and don’ts is not a sustainable strategy for managing chemical health risks and protecting public health. There are many good initiatives aimed at strengthening the testing and regulation of chemicals in Europe, and I wholeheartedly support their speedy implementation without any further delay!
Having said that, since this is one of the most common questions I receive, we carried out a small study on the connections between lifestyle and the concentrations of some chemicals in women’s ovaries. We found that women who reported using perfume daily had more phthalates in their ovaries compared to those who did not. We also found that women who consumed more fish and eggs had higher levels of PFAS in their ovaries.
This brings me back to the importance of political action. We can advise women to avoid perfume, but we cannot advise them to stop eating fish and eggs.
If you met a policymaker today, what would you ask them to do to protect women’s reproductive health?
I would ask them to immediately implement the chemical legislation updates from the Chemicals Strategy for Sustainability. For example, the anticipated updates to REACH would bring enhanced protection against endocrine-disrupting chemicals and chemical mixtures.
Around 70% of chemicals on the market have not been tested for toxicity towards human health, and it is impossible for consumers to know where they are. The products we buy in stores do not have detailed ingredient lists (except for certain categories like cosmetics and medicines). So when we find chemicals in the blood of women, it is impossible to tell how they ended up there.
Furthermore, reproductive toxicity testing is mandatory only for high-production volume chemicals, and those tests are based on rats, which are very fertile and, for example, never go through menopause.
Consequently, our understanding of how chemicals affect fertility in women, particularly those attempting to conceive their first child at around 30 years of age when fertility in humans naturally starts declining, is at best limited. It’s crucial to reassess how we study reprotoxicity in contexts more relevant to humans.
