Are endocrine disrupting chemicals driving down birth rates in Asia?

Contributors: Le Ye Lee, Shanna H. Swan, Terry Collins, Pete Myers, Seeram Ramakrishna

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Birth rates in Asia have been falling sharpely in recent decades. Fertility rates in Japan, China, Singapore, and South Korea are now at 1.34, 1.3, 1.1 and 0.84, respectively.  In Singapore, where the current fertility rate is among the lowest in the world, the average birth rate in 1959 was 5.8.

The Singapore government has instituted generous incentives to reverse this trend. Despite those efforts, the fertility rate remains stubbornly low. A similar situation has been reported recently in China, Japan and South Korea.

What’s behind this troubling decline? The explanation usually offered is that couples just aren’t trying to have babies, or trying too late in life.  They may choose not to become parents, or to limit family size perhaps because of Asians’ hard-work ethic, or the high cost of living, or a myriad of other concerns.  It is likely that these factors are all contributing to fertility decline.

But what if declines in reproductive health have impaired couple fertility, so that even couples who try to conceive are failing?  Careful, long-term research has demonstrated that the reproductive health of male and female has been declining for decades in many countries, and is  closely linked to a decline in semen quality. A 2017 landmark global study that included data on 43,000 men in western countries reported a decline of more than 50% in sperm count between 1973 and 2011.  While far fewer studies of semen quality have been conducted in Asia, the role of environmental chemicals in these declines have been widely recognized. 

A large body of science literature demonstrates how exposure to chemicals capable of altering the body’s own hormones, known as endocrine disrupting chemicals or EDCs, can impair male and female reproductive function and development. These changes are irreversible when exposure occurs during prenatal development.  This research shows unequivocally that exposure to EDCs during fetal development can set “timebombs” that impair semen quality and fertility in adulthood.

A co-author of this article, Shanna Swan, presented compelling research in her book Count Down (Scribner Press, 2021) linking EDCs exposure, including phthalates, bisphenols, pesticides and other commonly used chemicals to impiarments in multiple male and female reproductive endpoints.   These chemicals enter the human body via all routes,  which include ingestion, dermal exposure and inhalation and interfere with production and function of steroid hormones, such as testosterone and estrogen, which are essential for a health reproductive system. For example, prenatal exposure to the anti-androgenic (e.g. testosterone lowering), phthalates results in male infants being born “undermasculized”, with measurably smaller genitals. These changes have been shown in adult males to be correlated with low sperm counts and male infertility.

While it is difficult to predict the trend in sperm counts beyond 2011, the authors of Levine et al 2017 examined trends in recent years within the 39 years studied) and found no evidence that the trend has been “tapering off”.  However, in 2011, the mean concentration was only 47 million per ml, which is disturbingly close to 40 million per ml, the point at which the chances of conceiving a pregnancy decrease significantly, and the man is considered “subfertile”.  If the trend were to continue, increasing numbers of men would be subfertile and increasing numbers of couples would require assisted reproduction to conceive a child.

To reemphasize the basic science, endocrine hormones at extremely low concentrations in the body significantly control both how humans develop into what and who they become and day to day function. EDCs in ultra-low doses wreak havoc on this control. A considerable number of those EDCs interfere with testosterone’s role in directing development of the male reproductive organs. Among these EDCs are the phthalates and bisphenols, BPA and their look-alikes, which severely injure the developing male reproductive tract, and to which exposure is ubiquitous literally around the world.

How did we ever get into this predicament?

Typically, chemicals have made it to the market based only on their technical and cost performances—various chemicals doing something people want and can afford while the purveyor makes a profit.  The vast majority of these, however, were never tested for unintended consequences.  We have been naïve about what those might be, and are now paying the price.

The consequences for males with EDC exposures can include low sperm count, increased abnormal sperm, reduced penis size, undescended testicles, and hypospadias, where the urethra exits in the wrong place; all factors known to contribute to male infertility.

EDCs can also degrade the female reproductive system, resulting in miscarriages, endometriosis and poor egg quality and quantity. For example, a recent Scandinavian study showed that tissue levels of persistent pollutants are linked to a woman’s ovarian reserve.

The impacts of these exposures do not stop with the mother or the child she is carrying. Recent studies now show  adverse effects in later generations through exposure to the gametes carried by the exposed fetus.

What is being done?

Considering the immensity of this problem, the US and the EU have invested in research to detect and understand how EDCs function, and in biomonitoring to understand health trends in their citizenry.  EDCs are now shaping the European Union’s new Chemicals Strategy for Sustainability. The EU wants not just to solve the myriad problems that EDCs cause, but also become the world leader in sustainable chemistry and safe chemicals industry.

What should Asian countries do?

Asian countries should emulate the best pratices elsewhere, and commit the resources necessary to turn the tide of decreasing fertility to which EDCs contribute significantly.  These countries must prepare for a future supported by adequately tested  sustainable chemicals and a circular economy. 

Asian countries should initiate biomonitoring programs of their residents and require effective testing of new and existing chemicals in commerce.  They should invest in research that will allow us to reduce EDCs into Endocrine Disruption Free Chemicals, EDfCs. And importantly, they should develop a program of public health education to advise on what people can do to reduce their EDC exposures. All countries should invest in research that characterization and development of sustainable and green chemicals and facilitate companies that are striving to meet these criteria.

These measures are urgently needed to enable Singapore as well as East Asian countries to confront EDCs wisely, and ensure the resilience of their economies.

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Le ye Lee is a neonatologist at the National University Hospital with 3 teenagers and looks forward to a better future for them.

Shanna H. Swan is a Professor of Environmental Medicine and Public Health at the Icahn School of Medicine at Mount Sinai in New York City, and co-author of the book Count Down.

Pete Myers is the founder of Environmental Health Sciences.

Terry Collins is the Teresa Heinz Professor of Green Chemistry and Director of the Institute for Green Science at Carnegie Mellon University in Pittsburgh, Pennsylvania.

Seeram Ramakrishna is professor of materials engineering at the National University of Singapore. A member of ESG Committee of Singapore Insitute of Directors.

Seeram Ramakrishna, FREng, Everest Chair

Professor & Chair of Circular Economy Taskforce, National University of Singapore

UNESCO Global Expert Group member on the Universities & the 2030 Agenda (https://www.uib.no/en/sdgbergen/141236/members-unesco-expert-group).