Microplastics enter the human body daily through food, drinking water, and the very air we breathe, and mounting evidence shows they do not simply pass through. Laboratory analyses have now detected particles in virtually every organ—including the liver, kidneys, placenta and, most strikingly, the brain, where concentrations have risen by roughly 50 percent in less than a decade. Researchers have confirmed that some fragments are small enough to breach the blood–brain barrier, raising concern that accumulation in sensitive neural tissue may impair cognitive or neurological function over time.

Beyond their physical presence, microplastics behave like mobile toxic‑chemical sponges. Many are manufactured with—or absorb in transit—endocrine‑disrupting additives such as bisphenols, phthalates, and PFAS; once inside the body, these compounds can mimic or block natural hormones, affecting the thyroid, adrenal glands, reproductive organs, and developing fetuses. Recent toxicology reviews link sustained exposure to decreased fertility, altered puberty timing, and immune‑system dysregulation, underscoring the potential for lifelong health impacts.

At the cellular level, microplastics trigger a cascade of biochemical stress. Studies show they elevate reactive oxygen species (ROS), overwhelm antioxidant defenses, and activate inflammation pathways such as NLRP3 / Caspase‑1, which are associated with DNA damage, mitochondrial dysfunction, and heightened cancer risk. Inhalation experiments further reveal that nano‑sized plastics injure respiratory cells and may aggravate chronic lung conditions—findings echoed in emerging data on gut‑lining irritation and altered nutrient absorption after ingestion. 

System‑wide effects are also coming into focus, particularly for the cardiovascular system. Clinical cohorts with detectable microplastics in their bloodstream or arterial plaques exhibit up to twice the risk of heart attack or stroke, and animal studies show circulating particles can lodge in brain capillaries and promote clot formation. Physicians warn that any foreign debris that slows blood flow or aggravates vessel inflammation can accelerate atherosclerosis, meaning chronic exposure could compound other lifestyle risk factors. While researchers are still clarifying dose‑response relationships, the convergence of epidemiology, toxicology, and mechanistic biology signals a genuine public‑health concern that extends well beyond the environment itself.