What's Against Your Skin Matters More Than You Think
Men's reproductive health has been quietly declining for decades. The research points to an unlikely culprit — one most men wear 24 hours a day without a second thought.
Western men's sperm counts have dropped over 50% in recent decades. Researchers cite endocrine-disrupting chemicals as the leading environmental factor.[1]
Research has shown scrotal skin can absorb certain compounds up to 42× faster than the rest of your body — the highest absorption rate of any skin on the human body.[2]
Microplastics found in every single human testicular tissue sample examined — including endocrine-disrupting plastics PE, PVC, and PET.[3]
In a controlled human trial, 14 healthy men wore a polyester scrotal garment continuously. Every participant developed azoospermia — complete absence of sperm — within an average of 140 days. No pregnancies occurred among their partners during the study period.
After removing the polyester garment, sperm counts recovered and pregnancies followed.
Source: [6]In a parallel 24-month study, dogs wearing polyester underwear showed dramatic drops in sperm count and motility alongside degenerative testicular changes. Dogs wearing cotton underwear showed no changes whatsoever throughout the entire study period.
When polyester was removed from the polyester group, most dogs recovered. Two independent studies. Two species. Consistent findings.
Source: [7]Researchers found microplastics in every human testicular tissue sample they examined. These particles — including endocrine-disrupting plastics PE, PVC, and PET — can enter the body through ingestion, inhalation, and skin absorption, and may accumulate in reproductive organs.
Microplastics may act as "Trojan horses," potentially absorbing and transporting toxic chemicals into tissue. At the body's highest-absorption skin zone, researchers suggest daily contact with synthetic fabric may represent a direct exposure pathway.
Source: [3]Chemicals like phthalates — common in plastics and conventional fabric dyes — have been shown to inhibit steroidogenic enzymes and may interfere with hormone signaling. In animal studies, phthalate exposure has been associated with up to 40% reductions in serum testosterone alongside significant impairment of sperm production.
Research cited by the Endocrine Society links EDC exposure to significant sperm count declines in industrialized nations over the past half century. The higher the absorption rate at point of contact, the greater the potential daily chemical load on your hormonal system.
Sources: [1][4][5]Research suggests human sweat may actively leach toxic chemicals from synthetic fabrics through skin. Studies have found that certain chemicals from synthetic materials can absorb through skin within hours of direct contact.
At the body's highest-absorption zone, wearing synthetic underwear through a full day of activity — heat, moisture, friction — may create compounding chemical exposure that accumulates over years, not days.
Source: [8]The testicles require a temperature 2–7°C below core body temperature for healthy sperm production. Synthetic fabrics tend to trap heat against the body, potentially creating a microclimate that raises scrotal temperature and may disrupt spermatogenesis.
Research has linked elevated scrotal temperature to reduced sperm count, decreased motility, and abnormal sperm morphology. Even small, sustained increases in heat may compound over time.
Source: [9]We're not claiming your underwear is the whole problem. We're saying it's an unexamined variable — one that sits against your most absorbent skin, every single day, for your entire adult life.
Most men have never thought about it. That's exactly the point.
LOINS removes the variable. Certified organic cotton. Certified non-toxic dyes. 100% organic undyed liner at contact. No plastics, no forever chemicals, no compromises.
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Shop LOINS →References
- Levine, H. et al. (2017). Temporal trends in sperm count: a systematic review and meta-regression analysis. Human Reproduction Update, 23(6), 646–659. View study →
- Feldmann, R.J. & Maibach, H.I. (1967). Regional variation in percutaneous penetration of 14C cortisol in man. Journal of Investigative Dermatology, 48(2), 181–183.
- Zhao, Q. et al. (2024). Microplastics and nanoplastics in human testicular tissue. Science of the Total Environment. View study →
- Thacharodi, A. et al. (2023). Endocrine disrupting chemicals and their effects on the reproductive health in men. Environmental Research, 236(2), 116825.
- Endocrine Society. (2019). EDC impact on reproductive systems. View resource →
- Shafik, A. (1992). Contraceptive efficacy of polyester-induced azoospermia in normal men. Contraception, 45(5), 439–451.
- Shafik, A. (1993). Effect of different types of textile fabric on spermatogenesis — experimental study in dogs. Urological Research, 21(5), 367–370.
- Abdallah, M.A. et al. (2015). Dermal absorption of flame retardant chemicals from textiles. Environment International. See also: Abafe, O.A. et al. (2024). Sweat-mediated dermal absorption of chemicals from synthetic fabrics. Environmental Science & Technology.
- Mínguez-Alarcón, L. et al. (2018). Type of underwear worn and markers of testicular function among men attending a fertility center. Human Reproduction, 33(9), 1749–1756.
* This page is for informational purposes only and reflects peer-reviewed and developing scientific literature on environmental chemical exposure and male reproductive health. LOINS makes no claims that our products treat, prevent, diagnose, or cure any health condition. Individual results may vary. Consult a qualified healthcare provider with questions about your reproductive health.
