According to a 2017 study by Latif et al, a decline in sperm count might be considered as a ‘canary in the coal mine’ for male health and have much wider implications beyond fertility and reproduction.1
Endocrine disruption from chemical exposures to for example phthalates have been postulated as possible reasons for the increase in declining sperm counts and quality.
Recent studies have shown that poor sperm count is associated with overall morbidity and mortality. A Danish study report that with men with sperm concentration below 15 million/mL have a higher risk of diabetes and cardiovascular (CV) disease.2
An American study showed that diabetes is associated with a 16% increase in all‐cause and an 18% increase in CV mortality.3 According to the WHO, CVDs are the leading cause of death globally, responsible for an estimated 17.9 million deaths annually.4
What causes low sperm count?
Numerous environmental and lifestyle factors affect sperm count – both prenatally and in adult life. Endocrine disruption from chemical exposures or maternal smoking during critical windows of male reproductive development and lifestyle exposure to for example pesticides and other environmental toxins such as phthalates have been postulated as possible reasons for the increase in declining sperm counts and quality.1,3
Phthalate exposure linked to development abnormalities in male genitals
Phthalates such as Di(2-ethylhexyl)phthalate (DEHP) is widely used to make polyvinyl chloride soft and malleable, increase durability, transparency, and longevity to a variety of consumer, industrial, and medical products, including electronics, medical devices, children’s toys, detergents, pharmaceuticals, paints, waxes, personal care products, cosmetics, and food packaging, among others.5,6
Because phthalates are not covalently bound in these products, they can leach with product age, use, and ultraviolet light exposure, making them available for biological exposure.5 DEHP has come under increased scrutiny as its breakdown products are believed to be endocrine disruptors and more toxic than DEHP itself.6
The two most common endocrine developmental abnormalities of male genitals in infants, cryptorchidism, and hypospadias, have also shown increases – again particularly in Western, industrialised countries – over the past few decades.5
Shorter anogenital distance (AGD) are increasingly seen in boys with hypospadias and cryptorchidism. In men, shorter AGD has been linked to lower total sperm count and poor semen quality.5
In 2005, Swan et al published the first study the first study on AGD and other genital measurements in relation to prenatal phthalate exposure in 134 boys aged two- to 36-months. They found that phthalate metabolites are associated with short anogenital index and incomplete testicular descent. These data support the hypothesis that prenatal phthalate exposure at environmental levels can adversely affect male reproductive development in humans, conclude the team.7
Radke et al conducted a systematic review to identify male reproductive effects associated with phthalate exposure. According to the team, there is ‘robust evidence’ of an association between DEHP and dibutyl phthalate exposure (DBP) and male reproductive outcomes. The team showed links between AGD, semen parameters, and testosterone for DEHP exposure and semen parameters and time to pregnancy for DBP exposure.8
The future of the human race in peril?
In her book Count Down: How Our Modern World Is Threatening Sperm Counts, Altering Male and Female Reproductive Development, and Imperilling the Future of the Human Race, Dr Shanna Swan, an award-winning scientist based at Mount Sinai (United States) and one of the leading environmental and reproductive epidemiologists in the world, writes that changes in both male and female reproduction over the past few decades signal that ‘it’s no longer business as usual when it comes to human reproduction’. Reproductive changes have been noted in animals as well – signalling that something ‘very wrong is happening in our midst’.9
“This much is clear: The problem isn’t that something is inherently wrong with the human body as it had evolved over time, it’s that chemicals in our environment and unhealthy lifestyle practices in our modern world are disrupting our hormonal balance, causing various degrees of reproductive havoc that can foil fertility and lead to long-term health problems…”.9
She warns that we are living in an age of reproductive reckoning that has reverberating effects across the planet, and the longer it is allowed to continue, may threaten human survival.9
According to Dr Swan, reversing the various ‘reproduction-sabotaging effects’ will require fundamental change, including changing the kinds and volumes of chemicals we use in manufacturing.9
She also provides examples of practical, everyday solutions such as purging harmful chemicals from our homes by reading the ingredients on bathroom and kitchen cleaners. Choosing personal care products that are phthalate-free and paraben-free. Ditching air freshener and scented products. Not microwaving food in plastic, making sure to filter drinking water and toss out plastic food storage containers and non-stick cookware.9
Dr Swan concludes her book with a plea for swift national and global actions that ban the use of chemicals to mitigate the effects of those that are impacting health and even life itself.9
REFERENCES:
- Levine H, Jorgensen N, Swan SH, et al. Temporal trends in sperm count: a systematic review and meta-regression analysis. Human Reproduction Update, 2017.
- Latif T, Jensen K, Mehlsen J, et al. Semen quality is a predictor of subsequent morbidity. A Danish cohort study of 4,712 men with long-term follow-up. Am J Epidemiol, 2017.
- Raghavan S, Vassy JL, Ho Y-L, et al. Diabetes Mellitus–Related All‐Cause and Cardiovascular Mortality in a National Cohort of Adults. Journal of the American Heart Association, 2019.
- Cardiovascular disease. https://www.who.int/health-topics/cardiovascular-diseases#tab=tab_1
- Johnson KJ, Heger NE, Boekelheide K. Of mice and men (and rats): phthalate-induced fetal testis endocrine disruption is species-dependent. Toxicol Sci, 2012.
- Erythropel HC, Maric M, Nicell JA, Leask RL, Yargeau V. Leaching of the plasticizer di(2-ethylhexyl)phthalate (DEHP) from plastic containers and the question of human exposure. Appl Microbiol Biotechnol, 2014.
- Swan SH, Main KM, Liu F, et al. Study for Future Families Research Team. Decrease in anogenital distance among male infants with prenatal phthalate exposure. Environ Health Perspect, 2005.
- Radke EG, Braun JM, Meeker JD, Cooper GS.Phthalate exposure and male reproductive outcomes: A systematic review of the human epidemiological evidence. Environ Int. 2018.
- Swan SH and Colino S. Count Down: How Our Modern World Is Threatening Sperm Counts, Altering Male and Female Reproductive Development, and Imperilling the Future of the Human Race. Simon and Schuster, 2020.
