Review of Book 'Countdown - How our Modern World is Threatening Sperm Counts, Altering Male and Female Reproductive Development and Imperiling the Future of the Human Race'.

Book Cover with downwards arrow staircase in Red, Yellow and Black.
Book by Shanna H. Swan PhD

How our Modern World is Threatening Sperm Counts, Altering Male and Female Reproductive Development and Imperiling the Future of the Human Race

Schribner, 2020

At the start of 2022 there was a series of discussion programmes on Radio 4, Rethink Population, about the implications of falling birth rates around the world. To maintain a stable population there needs to be, on average, 2.1 births per woman. In the UK the birth rate has declined from 1.9 per woman in 2012 to just 1.58 in 2021. In Finland it has gone down from 1.9 to 1.4 within a decade. There are similar low rates across Western Europe, but also in the rest of the world: East Asia in particular has seen dramatic falls: the rate in Thailand is now lower than in the UK, and in South Korea it is just 0.9. In China it is 1.3. In half of countries the birth rate is now way below replacement levels. Even India is now below replacement level, at 2 per woman. Only in Africa is the birth rate sufficient to increase the population. In some countries, notably Hungary, Israel and France, declining fertility is becoming a political issue.

The guests on Rethink Population considered all sorts of factors that might be contributing to falling birth rates: the lack of affordable child care; the high cost of housing; young people not wanting to bring children into a world of climate chaos; concerns about over-population and a cultural change – young people not seeing their peers having children, so they don’t either. What was not mentioned, however, was the possibility that these declines are not simply a matter of human choices in response to changing socio-economic contexts and the climate and ecological crises, but may reflect a real decline in our capacity to reproduce ourselves. This is the argument made by Swan in Countdown: modern life is reducing our ability to have children by impairing our reproductive health. If things continue as they are this could be terminal for the human race.

This is not news. Thirty years ago (in 1992) a review by Danish researchers of studies of sperm in healthy men found that there had been a 45% fall in male sperm count between 1940 and 1990. Subsequent studies found that sperm count was related to the year of birth, not a man’s age – so in the 1990s younger men generally had a lower sperm count than older men. These findings were discussed in Our Stolen Future, by Theo Colborn, Dianne Dumanoski and John Peterson Myers, published in 1996. Swan, however, was one of those in the medical establishment who questioned the validity of the Danish research. She got together a team to review the study but after six months of number crunching came to the same conclusion. Since then she has become convinced that a dramatic decline in sperm counts is occurring and in 2017 published a meta-analysis that showed that between 1973 and 2011 the sperm count of men in Western Countries fell by 59%.

It is not just the number of sperm that is in decline, their quality is going down too, with more misshapen sperm and fewer sperm that are alive, or able to swim as they need to do to fertilise an egg. And low sperm counts go along with abnormalities in male genital development, such as undescended testes and hypospadias (where the opening of the urethra is in the wrong place on the penis) and other health problems such as testicular cancer. Swan says there has also been a decline in sex drive, and interest in sexual activity.

Women’s reproductive health is more difficult to monitor but various indicators suggest that it too is in decline, with increasing prevalence of disorders that affect fertility, such as polycystic ovary syndrome and endometriosis. The rates of miscarriages have been rising among women of all ages and there seems to be an increase in the problem of diminished ovarian reserve, where the quality and quantity of a woman’s eggs is reduced prematurely, making it harder for her to get pregnant. Swan says that the miscarriage rate, the rate of testicular cancer and of sperm count decline are all increasing by about 1% per year.

Swan discusses various lifestyle habits that can affect fertility. These include: smoking, stress, obesity, too much or too little exercise, too much alcohol (a moderate amount is good), consumption of processed meats and sugar-sweetened drinks, and opioid drugs. Paracetamol can also cause sperm abnormalities. The individual can do something about all of these, and if they take action their reproductive health is likely to recover. What they have less influence over is the endocrine-disrupting chemicals they are exposed to, particularly those that they were exposed to while in their mother’s womb, or in their mother’s milk. Exposure of the foetus, child or adolescent during critical stages of development to even very low concentrations of these synthetic chemicals that mimic or block oestrogen, testosterone or other hormones can have irreversible impacts on the reproductive health of the adult that the foetus, child or adolescent becomes.

Swan outlines some of the major types of chemicals that can affect our hormone system: phthalates – a diverse class of chemicals used in plastics and vinyl including floor and wall coverings, medical tubing, toys and a vast array of personal care products such as shampoos, perfumes and soaps; bisphenol A (BPA) - used in epoxy resins incorporated into protective coats such as the linings of food cans and various hard plastics, electronics and thermal receipt paper; the polybrominated diphenyl ethers present in flame retardants; perfluoroalkyl substances (PFAS) used as stain, water and grease-repellents; pesticides (unfortunately she gives little details as to which ones but cites evidence that men from rural areas in the US, where pesticide use is high, have poorer sperm quality and a greater body burden of herbicides and insecticides than urban men). Some of these chemicals, such as the brominated flame retardants and perfluoroalkyl substances do not easily degrade and persist in the environment, accumulating in the fat of animals; others, such as the bisphenols and phthalates are water-soluble so more easily degraded. The levels in human tissue, however, are often fairly stable because we are continually exposed to products that contain them. Swan outlines the evidence that these chemicals harm our reproductive health, and have other health impacts.

A growing human population has of course long been of concern to the environment movement and some may think that reduced human fertility could be a good thing. But while people deciding to have fewer children – because they have more confidence that those they do have will survive to adulthood, or so they can better look after the ones that they do have – may be good, the possibly terminal decline in human fertility caused by exposure to endocrine-disrupting chemicals is surely not. For one thing, these chemicals do not just harm us. We have spread them about the globe and throughout the environment. Swan gives some examples of their impact on wildlife, including on marine mammals such as seals, on alligators and panthers in Florida, on insect populations (and thus bird numbers) and fish. Poisoning ourselves means poisoning the other animals we share this planet with.

Secondly, the time delay of 20 years or more, between exposure in the womb and impacts on the adult being apparent, and the persistence of some of the chemicals of concern, mean that this is not a controllable situation we could easily reverse. Once we realise that human fertility is drastically impaired it will be very difficult to do anything about it. Assisted reproductive technologies, such IVF, may enable those able to afford them to have children, but there will come a point when even these technologies struggle.

Swan discusses the impacts that falling birth rates could have for societies, including the attempts in Japan and Singapore to increase the birth rate, attempts which have met with little success. We have some fictional warnings of what might happen. P.D. James’s 1992 novel, Children of Men, paints a dystopian picture of an England 26 years after the last baby was born worldwide – a sudden outbreak of mass infertility, the cause of which is not explained. Without children there is no future and little purpose to life. The ageing population tolerate an authoritarian government that prioritises security and comfort by permanently sending all those convicted of any crime to a penal colony on the Isle of Man. The elderly and infirm are forced into committing suicide to reduce the burden on others. Margaret Atwood’s The Handmaid’s Tale (1985) is in many ways more realistic as births have not stopped suddenly, but have much reduced over time, as a result of chemical pollution. In Gilead – the fundamentalist ‘Christian’ regime that has taken over much of the USA- the reaction to this situation is to exert control over women, forcing those thought to be fertile to have children for the elite, as their ‘handmaids’. Despite the fact that it takes two to make a baby and men’s as well as women’s reproductive health is in decline, it is easy to see how women could end up being blamed for falling birth rates and the progress we have seen in women’s rights put into reverse. An ominous indication of this comes as I write (in mid-March 2022): South Korea has just elected a new, conservative president who has said that feminism is to blame for the low birth rate in South Korea, a country that has a poor record on women’s rights. It is against this backdrop that there is an urgent need for more awareness of the impact of synthetic chemicals on reproductive health, and that our exposure to these chemicals, not just the choices being made by young men and women, is contributing to the decline in births. The solution is to stop producing and using synthetic chemicals that interfere with our hormone system, not to roll back the clock on women’s rights.

Swan outlines some things individuals can do to improve their reproductive health and reduce their exposure to harmful chemicals. (The ChemTrust website also has lots of good information). She also discusses some of the issues with the current regulatory system which means that it is not up to the task of protecting us from endocrine-disrupting chemicals, such as the assumption that harm is proportionate to the dose, whereas endocrine disruptors can have a greater negative impact at lower than higher doses, the timing of exposure being perhaps more critical, and how the ‘one chemical at a time approach’ allows one harmful chemical to simply be replaced by another one (such as BPA being replaced by BPS). The fundamental issues have not changed since I wrote about the problems with chemicals regulation in, Democratizing Technology, Risk, Responsibility and the Regulation of Chemicals, published in 2007. Our Stolen Future, published in 1996, and The Feminization of Nature, by Deborah Cadbury, published in 1997, alerted the world to the dangers of endocrine-disrupting chemicals 25 years ago. It is shocking that so little has been done since then to restrict their production and use.

Swan contrasts the concern and distrust expressed by some people about the safety of vaccines or fluoride in the water with the lack of upset about the presence of harmful endocrine-disrupting products in every-day products and asks ‘Where is the outrage on this issue?!’ This is a relatively easy to read book, with little stories about the experiences of particular individuals that I hope will help to build that outrage – though UK readers should remember that it is an American book, and some things are different (generally better on the chemicals front) in Europe (and the UK for the moment at least). We need to be much more worried and angry about endocrine-disrupting chemicals than we are. Continuing as we are is a recipe for disaster.

Count Down - Dr. Shanna Swan — Dr. Shanna Swan
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