Dr. Shanna Swan: How to Safeguard Your Hormone Health & Fertility

Experts raise alarms about the detrimental effects of hormone disrupting chemicals on male reproductive health, backing their claims with extensive research.

Phthalates and other chemical compounds can disrupt male sexual development and reproductive function through prenatal exposure

Researchers have indicated that prenatal exposure to endocrine disruptors like phthalates can lead to what is dubbed as "Phthalate syndrome" in male offspring, resulting in incomplete masculinization of male genitalia and other reproductive abnormalities. Shanna Swan confirms that exposure to substances such as DEHP can lead to smaller penis size, less testicular descent, and smaller scrotums in male children.

Studies on rats have been pivotal in understanding these effects, revealing that exposure to phthalates during a critical window of fetal development can lead to incompletely masculinized genitals in male offspring. These studies suggest that there is a specific critical window of exposure for genital development—Swan points out, in rats, this is around days 9 to 12 of gestation, and exposure outside this window does not seem to produce the same changes.

Studies in rats found adverse effects on male genital development

Experiments carried out by the National Toxicology Program on rats showed that male offspring born to mothers exposed to varying doses of phthalates during pregnancy exhibited a range of genital changes, collectively termed as the "Phthalate syndrome." These included smaller penis size, less testicular descent, and other genital malformations, all indicative of disrupted sexual development.

Link between human male fertility outcomes and prenatal exposure

Swan's research translated these findings to humans, studying prenatal phthalate exposure's effects on the genitalia of human male infants. She established a method to measure anogenital distance (AGD) in newborn boys and correlated it with prenatal phthalate exposure levels. Boys with a shorter AGD, a marker for fetal anti-androgen exposure, exhibited traits similar to the "Phthalate syndrome." Observations in male college students further supported these findings, with longer AGD associated with higher sperm counts.

Declining sperm counts and quality linked to environmental exposures

Declining male sperm counts have been related to environmental exposures rather than solely genetic or lifestyle factors. Studies indicate that men in areas with higher pesticide use have lower sperm counts. Certain environmental compounds like atrazine have been implicated in this decline.

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The influence of endocrine disruptors on women's reproductive health and fertility is raising concern, with substantial research suggesting a connection between chemical exposures and changes in reproductive development and milestones.

Women with polycystic ovarian syndrome (PCOS), which is characterized by elevated androgen levels, tend to have daughters with more masculine anogenital distance

Reproductive epidemiologist Shanna Swan's work examines the intricate relationship between chemical endocrine disruptors and fertility. Her research encompasses the effects of substances like oral contraceptives, which are intentionally designed to interfere with the endocrine system. Swan discusses a study that highlights the daughters of women with PCOS—a condition characterized by elevated levels of androgens—tending to have a more 'masculine' anogenital distance. This observation leads to the conclusion that prenatal androgen exposure can indeed masculinize the development of the female reproductive system.

Exposures to endocrine disruptors may be contributing to earlier onset of puberty and earlier menopause in women

Emerging research, noted by Swan, has drawn a ...

Research by experts like Swan and commentary by figures like Andrew Huberman reveal the distressing pattern of declining fertility rates in humans and other species, a phenomenon that signals broader societal challenges and illustrates the impact of environmental factors on reproductive health.

Declining fertility rates are not just a human phenomenon, but are observed across many animal species as well

Swan highlights that declining fertility rates are affecting not just humans but a broad spectrum of animal species. This pattern suggests that environmental changes, potentially linked to the use of plastics and pesticides that have proliferated since the 1950s, might be driving down reproductive rates across species. Swan points out that the rising number of species facing extinction supports the notion that the factors affecting human fertility are impacting other living organisms as well. Unlike humans, the fertility decline in non-human species cannot be chalked up to social factors like delayed childbearing or intentional contraception, pointing to more ubiquitous environmental factors at play.

Falling birth rates below replacement level in many countries pose significant societal challenges

Swan discusses the troubling global trend of birth rates declining below the critical threshold of replacement-level fertility, which is a rate of two. Falling below this level leads to a shrinking society. Some countries, like South Korea with a fertility rate of 0.78 and Japan with a rate of one, are already facing this reality. These demographic shifts can lead to an imbalance where a dwindling workforce must support an increasing elderly population, potentially undermining the economic and social structures that societies depend on.

Swan indicates that as fertility rates continue to decline, societies may become more reliant on medically assisted concept ...

Shanna Swan and Andrew Huberman discuss practical steps that individuals can take to reduce exposure to harmful chemicals known as endocrine disruptors, focusing on changes in food consumption, product choices, and storage practices.

Avoiding plastic food and beverage containers, especially for hot foods and drinks

Swan mentions that foodborne exposures and drinks are areas where individuals have some control over their contact with harmful substances. To reduce exposure to endocrine disruptors from plastics, Swan suggests buying in bulk and using a glass jar rather than choosing plastic-packaged items.

Plastic items can leach bisphenols and phthalates into the contents

Canned products are identified as a primary source of BPA exposure, with Swan advising against consuming foods and beverages that come in cans. She warns that many "BPA-free" products contain BPS or BPF, which are just as harmful due to their chemical similarity. She also warns against putting plastic in the microwave or leaving plastic bottles in hot cars, as these practices can cause chemicals to leach into food and water.

Choosing fragrance-free personal care and cleaning products

The use of fragrance-free products is inferred from discussions on being cautious about the chemical content in personal care products. Swan references using resources like the Environmental Working Group to flag products with harmful chemicals, including fragrances. She also explains that phthalates are often added to products like scented items and lipstick, as they hold scent and color well.

Fragrances often contain phthalates and other hormone-disrupting chemicals

Swan mentions the ubiquity of phthalates in personal care items designed for absorption, such as hand creams. She notes that anything intended to be absorbed is likely to contain phthalates. Her discussions with Huberman, covering safety concerns around household items such as soaps, body washes, cleaning sprays, and laundry detergents, suggest that c ...