TL;DR:

Testosterone levels in men have been declining for decades, even after accounting for age and lifestyle. Growing research suggests environmental chemicals—especially endocrine disruptors like phthalates, PFAS, bisphenols, and persistent pollutants—may be contributing by interfering with hormone signaling. These exposures don’t replace diet and lifestyle as factors, but they add an important and often overlooked layer to the discussion.

Researchers have reported a population-level decline in testosterone in U.S. men that doesn’t appear to be fully explained by aging, obesity, or other lifestyle factors. One well-known analysis found an age-independent drop across birth cohorts, suggesting broader influences may be involved [1]. More recently, researchers also reported declining testosterone levels in adolescents and young adult men in the U.S., raising concerns that this trend may be affecting younger generations too [2].

Why chemicals are being investigated

A growing body of research is looking at endocrine-disrupting chemicals (EDCs)—chemicals that can interfere with hormone signaling—as one possible contributor. These exposures are common and can come from plastics, personal care products, pesticides, industrial pollutants, and contaminated dust/food/water.

Phthalates (plasticizers): Multiple studies link higher phthalate exposure with changes in male reproductive hormones, including lower testosterone patterns in some datasets. A 2022 meta-analysis reviewed human evidence connecting phthalate exposure with sex steroid hormone changes [3].

PFAS (“forever chemicals”): Newer reviews summarize evidence that PFAS exposure may be associated with hormonal and reproductive effects, with testosterone frequently included among evaluated outcomes [4].

Dioxins and other persistent pollutants: Earlier research observed lower testosterone in groups with high dioxin exposure (such as certain military cohorts), supporting the concern that persistent pollutants may influence endocrine function [5].

Bisphenols (including BPA): BPA and related compounds remain under study for endocrine effects; recent reviews summarize mechanisms and human findings relevant to hormone disruption, and researchers continue investigating possible links with prostate biology and cancer risk [6].

References:

  1. Journal of Clinical Endocrinology & Metabolism. 2007;92(1):196–202. A population-level decline in serum testosterone levels in American men. doi:10.1210/jc.2006-1375.
  2. European Urology Focus. 2021;7(4):886–889. Decline in Serum Testosterone Levels Among Adolescent and Young Adult Men in the USA. (PubMed listing: PMID 32081788).
  3. Environ Int. 2018 Oct 16;121(Pt 1):764–793. Association between phthalate exposure and sex steroid hormones in men: A systematic review and meta-analysis.
  4. Frontiers in Endocrinology. 2025. Per- and polyfluoroalkyl substance exposure and testosterone levels: A systematic review.
  5. Environmental Health Perspectives. 2006;114(11). (Air Force/veteran dioxin-exposure evidence referenced in endocrine-disruptor literature.)
  6. 2023 review (PMC). Bisphenol A and endocrine-related outcomes (including male endocrine/prostate-relevant endpoints): updated review of mechanisms and human evidence.