Ultrafine Particles are Less than 0.1 Microns: UFP’s are Quite Common in our Environment and Very Dangerous

Nanotoxicology: An Emerging Discipline Evolving from Studies of Ultrafine Particles (2005)

From a Scientific Article by Günter Oberdörster (Dept. of Env. Medicine, Univ. of Rochester), Eva Oberdörster (Dept. of Biology, So. Methodist Univ.) and Jan Oberdörster (Toxicology Dept. at Bayer CropScience, Research Triangle Park, NC) in 2005

ABSTRACT — Although humans have been exposed to airborne nanosized particles (NSPs; < 100 nm) through-out their evolutionary stages, such exposure has increased dramatically over the last century due to anthropogenic sources. The rapidly developing field of nanotechnology is likely to become yet another source through inhalation, ingestion, skin uptake, and injection of engineered nano-materials. Information about safety and potential hazards is urgently needed.

Results of older bio-kinetic studies with NSPs and newer epidemiologic and toxicologic studies with airborne ultrafine particles can be viewed as the basis for the expanding field of nanotoxicology, which can be defined as safety evaluation of engineered nanostructures and nanodevices. Collectively, some emerging concepts of nanotoxicology can be identified from the results of these studies. When inhaled, specific sizes of NSPs are efficiently deposited by diffusional mechanisms in all regions of the respiratory tract.

The small size facilitates uptake into cells and transcytosis across epithelial and endothelial cells into the blood and lymph circulation to reach potentially sensitive target sites such as bone marrow, lymph nodes, spleen, and heart. Access to the central nervous system and ganglia via translocation along axons and dendrites of neurons has also been observed. NSPs penetrating the skin distribute via uptake into lymphatic channels.

Endocytosis and biokinetics are largely dependent on NSP surface chemistry (coating) and in vivo surface modifications. The greater surface area per mass compared with larger-sized particles of the same chemistry renders NSPs more active biologically. This activity includes a potential for inflammatory and pro-oxidant, but also antioxidant, activity, which can explain early findings showing mixed results in terms of toxicity of NSPs to environmentally relevant species.

Evidence of mitochondrial distribution and oxidative stress response after NSP endocytosis points to a need for basic research on their interactions with subcellular structures. Additional considerations for assessing safety of engineered NSPs include careful selections of appropriate and relevant doses/concentrations, the likelihood of increased effects in a compromised organism, and also the benefits of possible desirable effects.

An interdisciplinary team approach (e.g., toxicology, materials science, medicine, molecular biology, and bioinformatics, to name a few) is mandatory for nanotoxicology research to arrive at an appropriate risk assessment.

Reference: Environ Health Perspect 113:823–839 (2005). doi:10.1289/ehp.7339 available via http://dx.doi.org/ [Online 22 March 2005]

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NOTE: Diesel exhaust contains toxic air contaminants and is listed as carcinogenic for humans by the International Agency for Research on Cancer ( IARC ) in group 1. Diesel exhaust contains fine particles which are harmful. Diesel exhaust pollution was thought to account for around one quarter of the pollution in the air in previous decades, and a high share of sickness caused by vehicle pollution.

Tagged as: biokinetics, central nervous system, diesel exhaust, engineered nanomate- rials, environmental health, fossil fuel pollutants, human health, MTR, nanosized particles, respiratory tract, risk assessment, silica sand, skin, smoke, ultrafine particles