In the most recent study released just last week, a meta-analysis of 185 studies that sampled a total of 42,000 men across four decades from 1973 to 2013 confirms human sperm concentration and count are in a long-term decline of 50-60%, with no sign that the decline is slowing in North America, Europe, Australia and New Zealand.
Effects over generations
Of even greater concern was another very recent study, in July this year, which found that early life exposure of male mouse pups to an environmental estrogen, ethinyl estradiol, causes mistakes in development in the reproductive tract that leads to lower sperm counts in each successive generation.
While there are hundreds of studies linking Endocrine Disrupting Chemicals (EDCs) to male infertility, this study examined what happened when three successive generations of males were exposed, not just one generation. This approach is much more representative of what happens in the real world where successive generations have been exposed to a growing number of EDCs.
Each generation of mice was exposed for a brief period shortly after birth. Declining sperm counts and quality seen in the first exposed generation progressively worsened with each generation. The third generation animals were not able to produce sperm at all. The damage that was seen in any one generation got worse and worse as more generations were exposed.
There is now compelling evidence of the role of EDCs in male fertility.
The most compelling evidence comes from studies of diethylstilbestrol (DES) when it was prescribed to millions of pregnant women to prevent miscarriage. In DES sons and in male mice exposed prenatally to DES, the incidence of cryptorchidism, underdeveloped testes, and testicular cancer is increased, and sperm count and quality is decreased.
Link with everyday personal care products
However, a large number of studies have also linked EDCs found in common cosmetic and personal care products to male infertility. A growing number of studies also show exposure to these products is much higher than previously thought and in some cases they account for the largest exposure to EDCs.
It is estimated, for example, that exposure to parabens is 50 times more through application of these products through the skin than by ingestion.
Average exposure to parabens is estimated to be around 76 mg per day, which includes 1 mg daily from food, 50 mg from cosmetics and 25 mg from pharmaceuticals.
Our exposure to personal care products and cosmetics continues to increase each year.
According to the Environmental Working Group, on average, a woman will have around 185 chemicals on her skin daily, and a man will have around 85. A study on the extent to which we use these products found today’s usage of personal care products and cosmetics around six times more than in 1983. The average woman now uses around 12 cosmetics and up to 25 different products, with more than 25% of women using 15 or more a day, exposing themselves to hundreds of different chemicals every day. The average male uses half this quantity.
Some of these EDCs found in personal care products and cosmetics include parabens, phthalates, triclosan, aluminum, heavy metals and mineral oils.
Exposure to parabens, particularly butylparabens, in utero and in young males, can lead to decreased testosterone levels and reduced sperm counts. Daily sperm production and the efficiency in the testes decreased dramatically in test groups exposed to parabens. The sperm counts in the studies decreased in a dose-dependent manner—that is, the higher the paraben levels, the lower the sperm counts. Other studies have also shown exposure to pregnant female rats led to male offspring with decreased testes, seminal vesicle and prostate gland weights, as well as decreased sperm count and motility.
The research also reveals a strong link between phthalate exposure and increasing rates of male infertility and testicular cancer.
Studies on male rats and rabbits have indicated a positive correlation between exposure to one particular phthalate, dibutyl phthalate, and endocrine disruption, resulting in testicular and general reproductive abnormalities. A study on rabbits found that after exposure to dibutyl phthalate, rabbits exhibited symptoms of endocrine disruption including reduced testicle size, reduced sperm counts and reduced testosterone levels. As a result, many health and safety agencies around the world list dibutyl phthalate as a possible cause of birth defects and as a probable cause of testicular abnormalities.
Exposure to low levels of Bisphenol A during foetal development has also been shown to lead to a variety of reproductive problems in humans, including a lowered sperm count and infertile sperm. BPA has been linked with androgen (male hormone) receptors and is associated with a reduced proportion of male births in the populations and increased the risk of absence of a testicle, defects of the penis, and reduced semen quantity and quality in males. This is widely supported in animal studies and includes infertility and subfertility.
Additionally, decreased testosterone levels have been observed in rodents exposed to BPA during the prepubertal and pubertal period. In a study of 308 young men from the general population, researchers found that 98% of the men had detectable urinary levels of BPA and reported effects on the hypothalamic–pituitary–gonadal hormone feedback system. Researchers reported significantly higher concentrations of serum luteinizing hormone, testosterone and estradiol and a lower percentage of progressive motile sperm in healthy, young men. BPA has been shown to induce prostrate problems linked to prostate cancer in rodents.
Sunscreens a factor
Evidence for many animal reproductive studies has shown both estrogenic and anti-androgenic effects of BP-3 commonly found in sunscreens. A recent human study of 501 couples, where none had a medical diagnosis of infertility but were trying to conceive a child, found that men with high exposure to UV filters BP-2 or 2,4OH-BP (a breakdown product of BP-3) had a 30% reduction in fecundity, the biological ability to reproduce. Male fecundity seems to be more susceptible to these chemicals than female fecundity.
The good news is that many companies are now producing products without these chemicals so look for safer brands that tell you they have taken these chemicals out. If they don’t tell you, don’t buy the products. It is only through your personal choices that we can make a difference and get more companies to produce safer products.
Dr Dingle’s latest book Dangerous Beauty. The truth about cosmetics and personal care products is now out and available at https://www.drdingle.com/products/dangerous-beauty...
Dr Peter Dingle (PhD) has spent the past 30 years as a researcher, educator, author and advocate for a common sense approach to health and wellbeing. He has a PhD in the field of environmental toxicology and is not a medical doctor. He is Australia’s leading motivational health speaker and has 14 books in publication.