Aluminum oxide particles agglomerate strongly. The accumulations or clusters of particles formed that way are little toxic to cells.

 

Studies of Al, Al2O3, and AlOOH (boehmite) particles have shown that these particles tend to strongly clog and form agglomerates. These agglomerates can be taken up by the cells but are always found in vesicles, which means that they do not occur freely in the cells and are practically never detected in the cell nucleus [2,3,4,6].

Studies of human lung cells have shown Al2O3 to have only small harmful effects on the cell division and cell vitality and have proved that even very high doses do not cause formation of harmful reactive oxygen species (ROS) [7].

Aluminum oxide (Al2O3) which, for example, is used in orthopedic ceramics, has also been investigated for its genotoxicity. Very high doses were observed to have only minor mutagenic effects. Aluminum oxide fibers were found to be more genotoxic than nano- or micro-scale particles [1]. Aluminium particles are more toxic than aluminum oxide particles [4]. Only very high doses of Al2O3 can decrease the function of the mitochondria (only at or above 200 µg/ml, the function of the mitochondria is reduced by 15 %) and can cause (programmed) cell death of part of the cells [5, 6].

Boehmite, an aluminum oxihydroxide (AlOOH), was studied within the NanoCare project. For the human lung cell line A549, a threshold concentration of at least 50 µg particles per cm2 was determined. When the cells were treated with at least that concentration (LOEL) for more than 72 hours, they were observed to become stressed while inflammation markers were produced. No effects were triggered by low doses of AlOOH in any of the different cell lines of different origins [2]. Experiments on the mobility of nanoparticles across cell barriers (such as the air-blood barrier in the lung) showed that boehmite does not pass through cells. The barrier function of the cells is not influenced by the particles.

Using the so-called vector model which displays some of the elementary cell effects [8], partners of the NanoCare project proved that AIOOH particles are among the low-toxicity materials. Excessive, overloading concentrations of 60-120 µg particles per 106 macrophages were observed to damage the cells but did not lead to the formation of harmful reactive oxygen species (ROS) [2]. Damage due to realistic doses of Al particles is not expected.

 

 

Literature arrow down

  1. Tsaousi, A et al. (2010), Mutat Res, 697(1-2): 1-9.
  2. NanoCare 2009, Final Scientific Report, ISBN 978-3-89746-108-6. (PDF-Dokument, 19 MB).
  3. Monteiro-Riviere, NA et al. (2010), J Appl Toxicol, 30(3): 276-285.
  4. Wagner, AJ et al. (2007), J Phys Chem B, 111(25): 7353-7359.
  5. Jeng, HA et al. (2006), J Environ Sci Health A Tox Hazard Subst Environ Eng, 41(12): 2699-2711.
  6. Simon-Deckers, A et al. (2008), Toxicology, 253(1-3): 137-146.
  7. Kim, I-S et al. (2010), J Nanosci Nanotechnol, 10(5): 3453-3458.
  8. Bruch, J et al. (2004), Int J Hyg Environ Health, 207(3): 203-216.

 

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