Something strange is happening to the human male. The incidence of testicular germ cell tumours is increasingly dramatically in all the advanced economies on Earth, male infertility rates are at unprecedented levels, sperm counts are declining at an alarming rate and paternal impacts to the health and wellbeing if children are becoming ever more apparent (Aitken et al., 2020).
Testicular Cancer
Fifty years ago, nobody knew anybody who had suffered from testicular cancer. Now, we know someone who has contracted this disease including famous sports figures such as Lance Armstrong (cyclist), Scott Hamilton (figure skater) and Steve Scott (runner). Throughout the developed world, testicular cancer rates have been increasing at unprecedented rates. It is not , like prostate cancer, a function of increased longevity associated with advanced industrialised nations. It is also not a cancer that has miraculously appeared because we now have better methods of diagnosis. It is a cancer of young men exhibiting a peak incidence around the age of 30-34 years and associated with readily detectable changes in testicular size or shape, and, occasionally, the onset of pain in the testes or lower abdomen.
However, it still only represents less than 1% of all cancer cases. It is also easily treated, with a survival rate exceeding 95%. The treatments include removal of the affected area and chemotherapy. The removal of a single testis does not affect sexual performance or fertility. However treatments to kill the cancer do have a negative impact on sperm production. After a 12 month recovery recovery is usually complete and pregnancies can occur with the children appearing unaffected.
Cancer and opulence
Testicular cancer is not the only cancer to reflect socioeconomic status. A recent analysis of global cancer rates suggest a strong relationship between cancer incidence/mortality with the four-tier Human Development Index (HDI) – a summary measure of average achievement in key dimensions of human development, including a long and health life, education and gross national income per capita (Sung et a;., 2021) The higher the HDI, the greater the cancer burden in general and the greater the role of cancer in overall mortality rates. Cancer is 2.5 times more prevalent in high HDI countries than those exhibiting a low HDI (www.wcrf.org.diet and cancer/cancer-trends/comparing-more-and-less-developed-countries).
Other defects of the Male Reproductive Tract
The global trends in testicular cancer and prostatic cancer certainly suggest that something sinister is happening to male reproduction that is linked to environmental changes associated with demographic transition. The message is further emphasised when we look at other defects in male reproductive system. For example, hypospadias is a congenital condition which is a developmental abnormality of the urethra erupts on ejaculation , which is showing an upward trajectory. It has increased 1.6 times over a 30-year period between 1980 and 20210 (Yu et al., 2019).
The Vexed Question of declining sperm counts
There is also data suggesting that over the past 50 years sperm counts have halved, adding weight to the argument that reproduction is under attack from forces at present, unknown. Across the world, sperm counts are engaged in a steep descent that is somehow associated with the demographic transition and shows no sign of reversing.
Possible causes of declining sperm counts:
- Genetics – are likely to play a role in male infertility but unlikely to be a major factor in the global decline of sperm counts.
- Epigenetics – potential permanent genetic changes to the DNA sequence that defines the human genome.
- Environmental and lifestyle factors – this could be caused by smoking, cannabi use, alcohol consumption, recreational drugs. However the decline is global where attitudes to these activities differ greatly.
- Age – men do experience a decline in their sperm count as they age
- Abstinence – although there is still a decline in countries such as China where pornography is banned
Although none of these factors have any strong scientific evidence to support them as the major cause, all though each and all of them may be minor contributors in certain communities.
One potential factor could be our addition to highly processed foods. A high BMI and obesity are associated with a low sperm count. BMI alone is unlikely alone to be a factor, but when obesity is associated with a metabolic defect, then a decrease in semen quality is observed and this does affect sperm count (McPherson and Tremellen, 2020).
Combined, Westernised diets with high levels of alcohol consumption, cigarette smoking, recreational drug abuse, advanced age and limited abstinence and you have a heavy cocktail of factors that in combination, will have a significant negative effect on semen quality.
Environmental pollution and semen quality
The possibility that environmental toxicants in the water we drink, the food we eat and the air we breath could be responsible for declining sperm counts we see in advanced industrialised countries across a wide range of different political, cultural and social backgrounds is certainly plausible and backed by evidence.
Falling testosterone levels
Evidence has been presented indicating that testosterone levels have been declining since the 1970s ub concert with the decline in sperm counts.
There is abundant evidence to support the general concept that as societies engage the demographic transition and become more prosperous, there is a price to be paid in terms of human health. We may live longer, but we are seeing an increase in cancers that have powerful endocrine components, such as breast, prostate and testicular cancers. In parallel we are seeing a secular decline in sperm counts and emerging evidence that this decline is associated with the suppression of circulating testosterone levels. The elements if an advanced industrialised socially responsible for the suppression of testosterone in adult males is not known, but a reasonable hypothesis is that these changes reflect an increase exposure to oestrogen-like compounds emanating from, multiple sources, include”:
- Overweight males
- Increased dietary oestrogen
- Male ageing
- Lifestyle factors
- Exposure to environmental oestrogens
- Testosterone replacement therapy
In additional to psychological stress and genetic conditions
If sperm counts continue their current rate of decline, we shall, ultimately, arrive at a point where the damage to our fertility begins to bite. The next 20-30 years will be telling. It is a situation that we should be monitoring very carefully.
Extracts from The Infertility Trap: Why life choices impact your fertility and why we must act now, by, Laureate Professor John Aitken, Scientific Director Memphasys and Distinguished Emeritus Professor at the University of Newcastle, School of Environmental and Life Sciences (Biological Sciences)