Health and environmental risks of nanoparticles
Bonding, structure, and the properties of matter • Bulk and surface properties
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Key concepts
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Definition and distinctive properties
Nanoparticles are particles sized 1–100 nm in at least one dimension. Surface-area-to-volume ratio increases strongly as particle size decreases, so a larger fraction of atoms sits at the surface. Increased surface area often increases chemical reactivity and interaction with biological systems.
Routes of exposure and primary health effects
Inhalation, dermal contact and ingestion represent the main exposure routes for nanoparticles. Inhaled nanoparticles can penetrate deep into the lungs and enter the bloodstream. Dermal exposure can allow very small particles to reach deeper skin layers under certain conditions. Ingestion allows nanoparticles to interact with gut tissues and gut microbiota. Potential health effects include local inflammation, oxidative stress and cellular damage; systemic distribution can reach organs such as the liver and brain.
Environmental fate and ecological effects
Nanoparticles enter the environment via manufacturing effluent, product use and waste disposal. Environmental persistence depends on solubility, tendency to agglomerate and reactions with natural substances. Mobile nanoparticles can travel in water and air and interact with organisms at different trophic levels. Effects include toxic impacts on microorganisms, plants and animals, disruption of food chains and accumulation in sediments or tissues.
Key factors that increase risk
Risk increases with smaller size, higher surface reactivity, higher concentration (dose) and long persistence. Surface coatings, shape (e.g., fibers versus spheres) and solubility change how particles interact with cells and the environment. Exposure frequency and route also change risk: repeated inhalation of reactive nanoparticles presents a greater risk than rare, low-dose exposure.
Limitations, uncertainties and testing needs
Long-term effects and low-dose chronic exposure remain uncertain because of limited longitudinal data. Standardised test methods for environmental and health impacts are still developing. Interactions with other pollutants and transformation in real environments complicate risk prediction. Risk assessment requires toxicity tests, environmental monitoring and modelling that include realistic exposure concentrations.
Risk controls and responsible use
Risk controls include engineering controls in manufacturing, personal protective equipment, emissions treatment, product labelling and safe disposal methods. Lifecycle analysis reduces unintended releases by addressing production, use and waste stages. Regulation and continued research reduce uncertainty and support safer material design and handling practices.
Key notes
Important points to keep in mind