What's In Your Socks Is In Your Body

A global analysis estimated that exposure to DEHP, a common phthalate used to make plastic flexible, was linked to nearly 2 million preterm births in a single year. DiNP, a common replacement for DEHP, was linked to almost as many.

A prospective analysis of over 5,000 U.S. pregnancies found that phthalate metabolites detected in maternal urine were linked to reduced gestational age and a higher risk of preterm birth.

Histological analysis of human testicular tissue found microplastic particles present in every sample studied, showing these particles can cross biological barriers and accumulate in reproductive organs.

A laboratory study found that mice exposed to polystyrene microplastics over several weeks experienced a significant drop in testosterone, driven by oxidative stress that damaged the hormone-producing cells in the testes.

A systematic review of 22 separate studies found that most showed a connection between exposure to BPA and phthalates and the development of endometriosis.

A review of human and animal research found that higher phthalate exposure was linked to lower ovarian reserve, including fewer remaining egg cells and reduced levels of AMH, the hormone used to measure fertility potential.

The Endocrine Society's major scientific statement on hormone-disrupting chemicals found that BPA is linked to lower sperm quality, disrupted hormone signaling, and reduced fertility.

An investigation by the Center for Environmental Health tested socks from over 100 major clothing brands and found BPA levels as high as 31 times California's legal safety limit. Thirty of those companies later signed a legal agreement to remove BPA from their socks.

Researchers examined human semen samples using advanced lab techniques and confirmed the presence of microplastic particles in the majority of samples tested.

A multi-site study of 113 men found microplastics in every single semen and urine sample tested, with PTFE, the non-stick coating used in cookware, specifically linked to lower sperm count and slower sperm movement.

In 2023, the World Health Organization's cancer agency classified PFOA, a PFAS "forever chemical," as carcinogenic to humans, its highest category, with limited evidence in people linking it to kidney and testicular cancer.

The World Health Organization's cancer agency classified glyphosate, the active ingredient in Roundup, as probably carcinogenic to humans, citing limited evidence for non-Hodgkin lymphoma in people and sufficient evidence of cancer in lab animals.

In 2023, the World Health Organization's cancer agency upgraded trivalent antimony to "probably carcinogenic to humans." Antimony trioxide, a trivalent form, is the most common catalyst used to make polyester.

The International Agency for Research on Cancer's review of textile manufacturing chemicals identified short-chain chlorinated paraffins, used as flame retardants, as a potential human carcinogen, based on evidence from animal studies.

A 1999 review from the European Commission's scientific committee found that azo dyes used to color textiles can break down in the body into aromatic amines, some of which are classified as carcinogens.

A study of 17 common PFAS "forever chemicals" found that most of them can permeate the skin barrier and enter the bloodstream, disproving earlier assumptions that their electrical charge prevented skin absorption.

A NIOSH study testing anti-odor textiles found that silver nanoparticles release silver ions when exposed to sweat, with surface-coated fabric releasing more than twice as much as fabric with silver built into the fiber itself.

A review of 54 studies spanning over 20 years found that disperse dyes, the type used almost exclusively to color synthetic fabrics like polyester, are responsible for the majority of documented textile-related skin allergies.

The National Toxicology Program concluded that PFOA and PFOS, two of the most studied PFAS "forever chemicals," are presumed immune hazards to humans, citing evidence that they weaken the body's antibody response to vaccines.

A nationally representative study of more than 5,000 U.S. adults linked higher phthalate levels to higher death rates, especially from heart disease. Researchers estimated that 91,000 to 107,000 deaths a year among Americans aged 55 to 64 could be tied to this exposure.

A meta-analysis of seven studies covering more than 12,000 people found that higher urinary phthalate levels were linked to a greater risk of diabetes. People with the highest levels of DEHP, the most common plasticizer, had more than twice the odds.

A study of U.S. women found that those with the highest blood levels of PBDE flame retardants were significantly more likely to report a thyroid problem, with the strongest link found in postmenopausal women.

A human volunteer study measured how humidity affects skin absorption of a pesticide, finding that absorption rose from about 13% of the total dose at 50% humidity to as much as 63% at 90% humidity.

A laboratory study applied glyphosate directly to cotton fabric and tested whether it could penetrate human skin. It did, and absorption increased significantly when the fabric was wet.

A lab study testing actual textile samples found that benzothiazole, a chemical used in rubber and synthetic fabric production, penetrated a skin-mimicking membrane, with over 60% of the applied amount absorbed within 24 hours.

A meta-analysis of U.S. household dust studies found 45 potentially toxic chemicals from everyday products. Ten of them, including the phthalate DEHP and a flame retardant California lists as a carcinogen, showed up in 90% or more of samples.

Researchers analyzed human lung tissue and found microplastic particles in about 85% of samples, including nylon, a fiber specifically linked to clothing.

Researchers compared microfiber release from polyester clothing during washing and wearing. Within 20 minutes of normal activity, garments shed up to 400 fibers per gram of fabric. Wearing synthetic clothing for approximately three hours produced microfiber release comparable to a full wash cycle.

Researchers applied a physiologically based extraction test to measure how flame retardant additives (PBDEs) migrate from microplastics into simulated human sweat. Results confirmed that toxic chemical additives become bioaccessible through perspiration upon skin contact with microplastic particles.

Using 3D human skin equivalent models, researchers provided the first experimental evidence that flame retardant chemicals leached from microplastics can be absorbed through the skin barrier. Up to 8% of the exposure dose was absorbed. Sweatier skin increased absorption rates.

A peer-reviewed study published in Nature Communications found that synthetic clothing sheds at least ten times more microplastic fibers than cotton clothing, contributing an estimated 7.4 million metric tons of plastic pollution each year, much of which is eventually inhaled, ingested, or absorbed into the human body.

A comprehensive review of existing research found that microplastics are linked to health effects across multiple organ systems, including the skin, digestive tract, lungs, nervous system, and reproductive organs, with documented cell death and genetic damage in exposed tissue.

A study analyzing 57 clothing samples, including socks, detected BPA in both conventional and recycled polyester fabric. Recycled fabric contained nearly twice the BPA level of conventional fabric, and the recycled sock sample tested had the highest concentration found in the entire study.