In vitro exposure to ambient fine and ultrafine particles alters dopamine uptake and release, and D2 receptor affinity and signaling

The role of nanoparticles in bleed air in the etiology of Aerotoxic Syndrome: A review of cabin air-quality studies of 2003-2023

Aerotoxic Syndrome may develop as a result of chronic, low-level exposure to organophosphates (OPs) and volatile organic compounds in the airplane cabin air, caused by engine oil leaking past wet seals. Additionally, acute high-level exposures, so-called "fume events," may occur. However, air quality monitoring studies concluded that levels of inhaled chemicals might be too low to cause adverse effects. The presence of aerosols of nanoparticles (NPs) in bleed air has often been described. The specific hypothesis is a relation between NPs acting as a vector for toxic compounds in the etiology of the Aerotoxic Syndrome. These NPs function as carriers for toxic engine oil compounds leaking into the cabin air. Inhaled by aircrew NPs carrying soluble and insoluble components deposit in the alveolar region, where they are absorbed into the bloodstream. Subsequently, they may cross the blood-brain barrier and release their toxic compounds in the central nervous system. Olfactory absorption is another route for NPs with access to the brain. To study the hypothesis, all published in-flight measurement studies (2003-2023) of airborne volatile (and low-volatile) organic pollutants in cabin air were reviewed, including NPs (10-100 nm). Twelve studies providing data for a total of 387 flights in 16 different large-passenger jet aircraft types were selected. Maximum particle number concentrations (PNC) varied from 104 to 2.8 × 106 #/cm3 and maximum mass concentrations from 9 to 29 μg/m3. NP-peaks occurred after full-power take-off, in tailwind condition, after auxiliary power unit (APU) bleed air introduction, and after air conditioning pack failure. Chemical characterization of the NPs showed aliphatic hydrocarbons, black carbon, and metallic core particles. An aerosol mass-spectrometry pattern was consistent with aircraft engine oil. It is concluded that chronic exposure of aircrew to NP-aerosols, carrying oil derivatives, maybe a significant feature in the etiology of Aerotoxic Syndrome. Mobile NP measuring equipment should be made available in the cockpit for long-term monitoring of bleed air. Consequently, risk assessment of bleed air should include monitoring and analysis of NPs, studied in a prospective cohort design.

Adverse effects of exposure to fine particles and ultrafine particles in the environment on different organs of organisms

Particulate pollution is a global risk factor that seriously threatens human health. Fine particles (FPs) and ultrafine particles (UFPs) have small particle diameters and large specific surface areas, which can easily adsorb metals, microorganisms and other pollutants. FPs and UFPs can enter the human body in multiple ways and can be easily and quickly absorbed by the cells, tissues and organs. In the body, the particles can induce oxidative stress, inflammatory response and apoptosis, furthermore causing great adverse effects. Epidemiological studies mainly take the population as the research object to study the distribution of diseases and health conditions in a specific population and to focus on the identification of influencing factors. However, the mechanism by which a substance harms the health of organisms is mainly demonstrated through toxicological studies. Combining epidemiological studies with toxicological studies will provide a more systematic and comprehensive understanding of the impact of PM on the health of organisms. In this review, the sources, compositions, and morphologies of FPs and UFPs are briefly introduced in the first part. The effects and action mechanisms of exposure to FPs and UFPs on the heart, lungs, brain, liver, spleen, kidneys, pancreas, gastrointestinal tract, joints and reproductive system are systematically summarized. In addition, challenges are further pointed out at the end of the paper. This work provides useful theoretical guidance and a strong experimental foundation for investigating and preventing the adverse effects of FPs and UFPs on human health.

Effect of subchronic exposure to ambient fine and ultrafine particles on rat motor activity and ex vivo striatal dopaminergic transmission

Alterations in dopaminergic transmission are associated with neurological disorders, such as depression, autism, and Parkinson's disease. Exposure of rats to ambient fine (FP) or ultrafine (UFP) particles induces oxidative and inflammatory responses in the striatum, a neuronal nucleus with dense dopaminergic innervation and critically involved in the control of motor activity.Objectives: We used an ex vivo system to evaluate the effect of in vivo inhalation exposure to FP and UFP on motor activity and dopaminergic transmission.Materials and Methods: Male adult Wistar rats were exposed to FP, UFP, or filtered air for 8 weeks (subchronic exposure; 5 h/day, 5 days/week) in a particle concentrator. Motor activity was evaluated using the open-field test. Uptake and release of [³H]-dopamine were assessed in striatal synaptosomes, and dopamine D₂ receptor (D₂R) affinity for dopamine was evaluated by the displacement of [³H]-spiperone binding to striatal membranes.Results: Exposure to FP or UFP significantly reduced spontaneous motor activity (ambulatory distance: FP -25%, UFP -32%; ambulatory time: FP -24%, UFP -22%; ambulatory episodes: FP -22%, UFP -30%), decreased [³H]-dopamine uptake (FP -18%, UFP -24%), and increased, although not significantly, [³H]-dopamine release (113.3 ± 16.3 and 138.6 ± 17.3%). Neither FP nor UFP exposure affected D₂R density or affinity for dopamine.Conclusions: These results indicate that exposure to ambient particulate matter reduces locomotion in rats, which could be related to altered striatal dopaminergic transmission: UFP was more potent than FP. Our results contribute to the evidence linking environmental factors to changes in brain function that could turn into neurological and psychiatric disorders.HIGHLIGHTSYoung adult rats were exposed to fine (FP) or ultrafine (UFP) particles for 40 days.Exposure to FP or UFP reduced motor activity.Exposure to FP or UFP reduced dopamine uptake by striatal synaptosomes.Neither D₂R density or affinity for dopamine was affected by FP or UFP.UFP was more potent than FP to exert the effects reported.