Nanoparticles: Health Risks, Exposure Routes, and Long-Term Effects
- Tiny particles measuring less than 100 nanometers—known as nanoparticles, ultrafijnstof, and nanoplastics—are increasingly detected in human organs, sparking renewed scrutiny from health authorities across Europe.
- Human exposure to these microscopic materials occurs through three primary routes: inhalation, ingestion, and dermal absorption.
- Unlike soluble substances that disperse and leave the body relatively quickly, poorly soluble nanoparticles behave differently once they enter the bloodstream.
Tiny particles measuring less than 100 nanometers—known as nanoparticles, ultrafijnstof, and nanoplastics—are increasingly detected in human organs, sparking renewed scrutiny from health authorities across Europe. While regulators have already banned certain food additives over uncertainty regarding DNA damage, researchers continue to investigate how these microscopic fragments travel through the body and where they accumulate.
Where Nanoparticles and Ultrafijnstof Enter the Body
Human exposure to these microscopic materials occurs through three primary routes: inhalation, ingestion, and dermal absorption. Ultrafijnstof generated by traffic and aviation ranges from 10 to 50 nanometers in size, allowing these particles to pass through the lungs directly into the bloodstream and reach other vital organs. Scientific observations also suggest that inhaled particles can travel from the nose to the brain via the olfactory nerve. Ingestion accounts for another intake route, though the European Food Safety Authority (EFSA) estimates that only a maximum of 0.5 percent of titanium dioxide found in food is actually absorbed by the body. Meanwhile, dermal absorption studies on sunscreen containing titanium dioxide or zinc oxide nanoparticles show that the particles remain restricted to the uppermost layer of the skin, even when the skin is damaged or sunburned. The European Commission’s Scientific Committee on Consumer Safety (SCCS) concluded that nano titaniumdioxide concentrations up to 25 percent in sunscreen pose no risk on healthy or burned skin, though inhaled titanium dioxide remains classified as a suspected carcinogen, prompting stricter rules for sprays and powders.
Accumulation in Human Organs and Tissue Discovery
Unlike soluble substances that disperse and leave the body relatively quickly, poorly soluble nanoparticles behave differently once they enter the bloodstream. White blood cells rapidly ingest them, meaning blood samples typically show little to no trace of the particles. Instead, the material accumulates primarily in the liver, spleen, lungs, and lymph nodes, where it can persist for months or even years. Animal studies tracking 21-nanometer particles have shown widely varying clearance rates; one study observed that the quantity in the liver halved after 95 days, while another recorded 265 days for the same reduction. Human accumulation was confirmed in 2018 when researchers first identified titanium and titanium dioxide particles in the liver and spleen of 15 deceased individuals, with at least 24 percent falling into the nano range. A subsequent study detected both titanium dioxide and silica particles in human tissue. A 2025 study discovered nanoplastics—primarily polyethylene in the form of microscopic nanosized shards—in the kidneys, liver, and brains of deceased subjects, with brain tissue showing the highest concentrations and visibly larger plastic accumulation in samples from 2024 compared to 2016.
Regulatory Actions and Scientific Uncertainty
The precise health impacts of these accumulated particles remain largely undetermined, prompting different responses from international food safety regulators. In 2019, EFSA and the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) declared that previous safety conclusions regarding titanium dioxide (E 171) no longer held up, primarily because thorough toxicity tests were lacking rather than because the substance was proven toxic. Because EFSA concluded in 2021 that DNA damage could not be excluded, the European Union banned the production and importation of foodstuffs containing E 171 starting August 8, 2022. However, other international bodies maintain divergent stances; Health Canada, Australia and New Zealand’s FSANZ, and the British Food Standards Agency (FSA) weigh the available data differently. Regarding nanoplastics, findings remain concerning yet difficult to verify definitively. An Italian study tracking patients undergoing carotid endarterectomy found polyethylene in the fatty plaque of over 58 percent of participants, who subsequently experienced a 4.5 times higher risk of heart attack, stroke, or death, though critics note that operating rooms contain substantial plastic equipment that can potentially contaminate tissue samples. Similarly, skepticism surrounds brain tissue studies, with independent researchers questioning whether current measurement techniques can accurately distinguish microscopic plastics from natural substances in neural tissue. For ultrafijnstof, the health picture is somewhat sharper, as exposure is known to trigger lung inflammation and potential cardiovascular effects, yet official legal limit values for ultrafijnstof do not currently exist.