Do Microplastics Affect Hormones

⚕️ MEDICAL DISCLAIMER: This article is for informational and educational purposes only and is not intended as medical advice, diagnosis, or treatment. Always consult with a qualified healthcare provider before making any changes to your health regimen, diet, or supplement use, especially if you have existing medical conditions or take medications. The information presented here should not be used to diagnose, treat, cure, or prevent any disease.

Our hormones influence our growth, energy, reproduction, metabolism, and stress responses. They’re in constant communication with one another, and have delicate feedback loops to ensure they remain balanced. Microplastics disrupt this equilibrium in multiple ways [1–3]. By swaying this balance, microplastics affect hormones. For example, they can release endocrine-disrupting chemicals (EDCs), adsorb environmental pollutants, and directly interfere with hormone production and signaling. This can result in a destabilized hormonal network spanning reproductive, thyroid, and adrenal systems, with consequences that ripple across metabolism, immunity, and development. 

Endocrine-Disrupting Chemicals Within Microplastics

Plastics are manufactured with a suite of additives including plasticizers, flame retardants, antioxidants, UV stabilizers, many of which are EDCs [1, 4]. These compounds mimic or block natural hormones, binding to receptors or interfering with enzymes involved in hormone synthesis [5, 6]. Bisphenol A (BPA) and phthalates exemplify this risk. Both of these compounds mimic estrogen and testosterone, distorting hormonal signaling [5]. Other plastic-derived compounds downregulate steroidogenic proteins such as StAR, crippling steroid hormone production [2, 9]. Beyond intrinsic additives, microplastics also absorb heavy metals and pesticides from the environment, with the potential to act as endocrine disruptors in the body [3, 10].

How Microplastics Disrupt the Hypothalamic-Pituitary-Gonadal Axis

The hypothalamic-pituitary-gonadal (HPG) axis is especially vulnerable to microplastics. In female animal studies, microplastic exposure reduced ovarian follicles, decreased anti-Müllerian hormone and estradiol, and induced irregular cycles and delayed maturation [1, 11]. In males, serum levels of testosterone, luteinizing hormone, and follicle-stimulating hormone decline, while estradiol rises, leading to feminization and impaired sperm quality [1, 12–14]. Microplastics infiltrate Leydig cells, disrupting the LH-driven LHR/cAMP/PKA/StAR pathway, which is central to testosterone synthesis [11].

This can result in impaired gametogenesis, the production of sperm and eggs. Oocytes show abnormal differentiation, ovarian tissues lose metabolic stability [4], and spermatogenesis suffers, producing fewer, less motile, and more abnormal sperm [5, 11–14]. In short, microplastics can disrupt fertility and reproductive health. 

How Microplastics Disrupt The Thyroid and Metabolism

The hypothalamic-pituitary-thyroid (HPT) axis regulates energy metabolism and development. Polystyrene nanoplastics suppress thyroid hormones T3 and T4, while elevating thyroid-stimulating hormone (TSH) [1, 11]. This dysregulation slows metabolic function and impairs growth, reproduction, and neurological development. Thyroid disruption is particularly concerning during pregnancy and childhood, when T3 and T4 are critical for brain maturation. 

How Microplastics Affect The Adrenal System And Impact Stress and Cortisol

Microplastics also target the hypothalamic-pituitary-adrenal (HPA) axis, destabilizing the body’s stress response. Polyethylene particles have been shown to reduce cortisol levels, while elevating adrenocorticotropic hormone, suggesting impaired adrenal feedback loops [2]. Structural damage to adrenal cortex tissue and altered expression of steroidogenesis-related genes (StAR, Cyp11A1, Cyp11B1) also show that microplastics impact the adrenal system [2, 11]. These shifts compromise resilience to stress and disrupt energy balance. 

Specific Hormones That Are Impacted By Microplastics

Microplastics have been shown to affect many hormones, including: 

• Estrogen: Microplastics act as estrogen receptor agonists, elevating estrogen activity in both sexes and contributing to feminization in males [1, 5, 11, 15, 16].
• Testosterone: Reduced via mitochondrial oxidative stress, apoptosis, and pathway inhibition, affecting muscle mass, fat distribution, and mood [5, 11, 12, 17].
• LH and FSH: Both of these hormones are suppressed by microplastic exposure, undermining gonadal function and hormone synthesis [1, 8, 11].
• Thyroid hormones (T3, T4): Both of these are suppressed by microplastics, destabilizing metabolic regulation [11].
• Cortisol: Reduced after microplastic exposure in animal models, undermining immune balance and stress resilience [2].
• Kisspeptin: Declines after exposure to microplastics, impairing reproductive signaling [11].

Mechanisms Driving Microplastic-Induced Endocrine Disruption

Microplastics disrupt hormones through several intertwined pathways. Firstly, they can bind directly to receptors and act as hormone mimics or blockers [5]. Additionally, they can interfere with enzymes, disrupting steroidogenesis and hormone metabolism [2, 11]. Moreover, microplastics can interfere with gene expression and alter transcription of hormone receptors and steroidogenic enzymes [1,2,4,7,11,16]. Microplastics also induce oxidative stress and damage endocrine cells which regulate hormonal pathways [2,5,11,17-19]. Chronic oxidative stress promotes low-grade inflammation, which can further undermine endocrine function and feedback systems [2,5,11,16]. Overall, microplastics can impact the endocrine system in a number of ways. 

The Low-Dose Effect and Sex-Specific Impacts of Microplastics and EDCs

Interestingly, studies have shown that microplastics and EDCs can exert stronger disruptions at very low concentrations, rather than at higher ones, defying conventional toxicology [20]. Because hormones function at trace levels, even minimal exposure can destabilize endocrine systems. These effects vary by sex. For example, in some studies, females show stronger impacts to reproductive function, while in other studies, male organisms exhibit greater susceptibility to toxicity [21, 22]. These differences highlight the nuanced vulnerabilities of endocrine biology, and how small disruptions via microplastics and EDCs can have large effects. 

Microplastic-Induced Endocrine Disruption Beyond Reproduction

Hormonal imbalances affect most biological pathways, not just the endocrine system itself. For example, microplastic-induced thyroid and adrenal disruptions impair metabolism, weight regulation, and stress responses [1, 2, 11].  Endocrine disruption also can influence immunity, causing us to be more susceptible to infections [1]. Studies have shown that exposure to microplastics can also cause behavior changes like those linked to altered neurotransmitter levels and reduced acetylcholinesterase activity [11]. Hormones, being key biological regulators, are highly susceptible to microplastic-induced dysregulation. 

A Hormonal World Rewritten

Microplastics destabilize hormonal balance by releasing endocrine disruptors, hijacking signaling pathways, and impairing endocrine axes. They mimic estrogen, suppress testosterone, silence thyroid output, and distort cortisol feedback. These changes affect fertility, metabolism, immunity, and stress resilience. In short, plastics rewire the hormonal symphony, replacing balance with dissonance.

Hormones define who we are—our development, our fertility, our resilience. Microplastics are rewriting this code at the molecular level. At Deplasto, we expose how invisible particles destabilize hormonal balance, so you can see the hidden costs of plastic woven into everyday life.

Sources

1. A systematic review of microplastics emissions in kitchens- Understanding the links with diseases in daily life
2. Melatonin counteracts polyethylene microplastics induced adreno-cortical damage in male albino rats
3. Health Effects of Microplastic Exposures- Current Issues and Perspectives in South Korea
4. Behavioral Studies of Zebrafish Reveal a New Perspective on the Reproductive Toxicity of Micro- and Nanoplastics
5. Can Mammalian Reproductive Health Withstand Massive Exposure to Polystyrene Micro- and Nanoplastic Derivatives_ A Systematic Review
6. Adverse health effects of exposure to plastic, microplastics and their additives- environmental, legal and policy implications for Israel
7. Effects of polystyrene micro- and nanoplastics on androgen- and estrogen receptor activity and steroidogenesis in vitro
8. Impact of polyethylene microplastics exposure on kallikrein-3 levels, steroidal-thyroidal hormones, and antioxidant status in murine model- protective potentials of naringin
9. Combined effects of polystyrene nanoplastics and lipopolysaccharide on testosterone biosynthesis and inflammation in mouse testis
10. Microplastics in the Human Body- Exposure, Detection, and Risk of Carcinogenesis- A State-of-the-Art Review
11. Detrimental consequences of micropolymers associated plasticizers on endocrinal disruption
12. Microplastics exposure- implications for human fertility, pregnancy and child health
13. Detection and quantification of microplastics in various types of human tumor tissues
14. Microplastics in maternal blood, fetal appendages, and umbilical vein blood
15. Microplastics impair the reproductive behavior and life history traits of the amphipod Parhyale hawaiensis
16. A review of the neurobehavioural, physiological, and reproductive toxicity of microplastics in fishes
17. Chronic Polystyrene Microplastic Exposure Reduces Testosterone Levels in Mice through Mitochondrial Oxidative Stress and BAX_BCL2-Mediated Apoptosis
18. Effects of Polyvinyl Chloride Microplastics on the Reproductive System, Intestinal Structure, and Microflora in Male and Female Mice
19. Microplastics detected in three types of female reproductive organs using micro-Raman spectroscopy
20. Microplastics may induce food dilution and endocrine disrupting effects in fathead minnows (Pimephales promelas), and decrease offspring quality
21. Female zebrafish are more affected than males under polystyrene microplastics exposure
22. Effects of Polyvinyl Chloride (PVC) Microplastic Particles on Gut Microbiota Composition and Health Status in Rabbit Livestock