Summary
Rising global plastic production has led to widespread contamination by microplastics (MPs) and nanoplastics (NPs), raising serious concerns for mammalian endocrine health because these particles carry and release endocrine-disrupting chemicals (EDCs). Beyond their own physical toxicity, MPs and NPs readily absorb harmful additives and environmental pollutants—including bisphenols, phthalates, flame retardants, dioxins, PAHs, and heavy metals—then act as transport vehicles that deliver these compounds into the body. Since these additives are not chemically bound to plastics, they can leach into food, water, and biological fluids, ultimately disrupting hormone signaling. Smaller particles in particular pose greater risk because their larger surface-area-to-volume ratio increases absorption, bioaccumulation, and release of toxicants. By mimicking or blocking natural hormones, EDC-loaded MPs and NPs interfere with the hypothalamic-pituitary axes that regulate thyroid, adrenal, testicular, and ovarian function, triggering oxidative stress, reproductive toxicity, neurotoxicity, inflammation, developmental issues, and reduced sperm quality. Strong evidence documents direct impacts on the thyroid, testes, and ovaries, while the effects on the hypothalamus, pituitary, and adrenal glands remain under-studied. Overall, the review highlights how increasing exposure to MPs and NPs poses a significant, size-dependent hazard to mammalian endocrine systems.
PMID: 36726457
PMCID: PMC9885170
DOI: 10.3389/fendo.2022.1084236
Abstract
Over the years, the vaste expansion of plastic manufacturing has dramatically increased the environmental impact of microplastics [MPs] and nanoplastics [NPs], making them a threat to marine and terrestrial biota because they contain endocrine disrupting chemicals [EDCs] and other harmful compounds. MPs and NPs have deleteriouse impacts on mammalian endocrine components such as hypothalamus, pituitary, thyroid, adrenal, testes, and ovaries. MPs and NPs absorb and act as a transport medium for harmful chemicals such as bisphenols, phthalates, polybrominated diphenyl ether, polychlorinated biphenyl ether, organotin, perfluorinated compounds, dioxins, polycyclic aromatic hydrocarbons, organic contaminants, and heavy metals, which are commonly used as additives in plastic production. As the EDCs are not covalently bonded to plastics, they can easily leach into milk, water, and other liquids affecting the endocrine system of mammals upon exposure. The toxicity induced by MPs and NPs is size-dependent, as smaller particles have better absorption capacity and larger surface area, releasing more EDC and toxic chemicals. Various EDCs contained or carried by MPs and NPs share structural similarities with specific hormone receptors; hence they interfere with normal hormone receptors, altering the hormonal action of the endocrine glands. This review demonstrates size-dependent MPs’ bioaccumulation, distribution, and translocation with potential hazards to the endocrine gland. We reviewed that MPs and NPs disrupt hypothalamic-pituitary axes, including the hypothalamic-pituitary-thyroid/adrenal/testicular/ovarian axis leading to oxidative stress, reproductive toxicity, neurotoxicity, cytotoxicity, developmental abnormalities, decreased sperm quality, and immunotoxicity. The direct consequences of MPs and NPs on the thyroid, testis, and ovaries are documented. Still, studies need to be carried out to identify the direct effects of MPs and NPs on the hypothalamus, pituitary, and adrenal glands.
Keywords: microplastics, nanoplastics, mammalian endocrine system, endocrine abnormalities, endocrine disrupting chemicals, plastic additives, environmental pollution
Ullah S, Ahmad S, Guo X, Ullah S, Ullah S, Nabi G, Wanghe K. A review of the endocrine disrupting effects of micro and nano plastic and their associated chemicals in mammals. Front Endocrinol (Lausanne). 2023 Jan 16;13:1084236. doi: 10.3389/fendo.2022.1084236. PMID: 36726457; PMCID: PMC9885170.