Metallilised nanoosakesed (Metallic nanoparticles)

EPLis on täna huvitav artikkel "Metallilised nanoosakesed ei ole elusolenditele ohutud". KBFI teadurid uurisid TiO2, ZnO ning CuO (vaskoksiid, mineraalmeigis ei kasutata) ohtlikkust pisiorganismidele (bakterid, kirpvähilised ja vesikirbud). Siin on link ka KBFI kodulehel üllitatud vastavasisulisele pdf-failile.
Kokkuvõte: äärmiselt mürgised on nanotsinkoksiid ja nanohõbe, titaandioksiid pisiloomadele mürgiseks ei osutunud.

Teadusuuringud näitasid, et kirpvähilistele Daphnia magna ja Thamnocephalus platyurus, bakteritele Vibrio fischeri ja pärmidele Saccharomyces cerevisiae ei olnud nano- ega ka tavasuuruses TiO2 suspensioonid toksilised isegi kontsentratsioonis 20 g/l. ZnO- (nano)osakesed olid aga TiO2-osakestest tunduvalt toksilisemad, kusjuures nano- ja tavasuuruses osakeste toksilisus oli ühesugune*. Samasugused ZnO toksilisuse kohta käivad tulemused saadi vetikatega Pseudokirchneriella subcapitata ja osakestest toituvate algloomadega Tetrahymena thermophila. Kõikidele testorganismidele oli nanosuuruses CuO kuni kuuskümmend korda toksilisem kui CuO tavasuuruses osakesed

* vahe selles, et tavaosakesed ei läbista nahka ja ei satu puudrist me vereringesse.

See uudis puudutab kosmeetikatarbijaid päris otseselt, sest nanovormis ZnO ning TiO2 on paljude päikesekaitsekreemide koostises ning nanohõbedaosakesed on nt nendes poppides bakteritsiidsetes hõbedasokkides ning haavaplaastrites.

Miks "nano" nii ohtlik on:

Aine „lõhkumine” nanosuuruseni suu rendab aine eripinda kuni miljoneid kordi, muutes aine keemiliselt reaktiivsemaks. See on ka peapõhjus, miks nanorevolutsioonile nii suurt tulevikku ennustatakse: samal ainel on nanosuuruses täiesti uued omadused, millest võib võita nii tööstus kui ka meditsiin. Teisalt võivad nanoskaalas materjalide uudsed füüsikalis-keemilised omadused suurendada nende biosaadavust ning toksilisust.

Estonian scientists studied the effects of micronized zinc oxide, titanium dioxide and copper oxide on various micro organisms: bacteria and small water organisms Daphnia magna ja Thamnocephalus platyurus. Results: no toxicity in TiO2 but ZnO was highly toxic - and this not only in micronized form - the ordinary ZnO ocurred as toxic for the test subjects. Now this is not something for us to be very concerned about cause ZnO is a well known antibiotic and in ordinary size it cannot penetrate the cells, can't get through our skin - but the micronized version is likely to cause some damage. Micronized CuO was about 60 times more toxic then it's ordinary version. Nanosilver was also found to be highly toxic and it is by now widely used in socks, medical bandages and special underwear.

Anybody looking for more can look up these research papers:

Aruoja, V., Dubourguier, H.C., Kasemets, K., Kahru, A., 2009. Toxicity of nanoparticles of CuO, ZnO and TiO2 to microalgae Pseudokirchneriella subcapitata. Sci. Total. Environ. 407, 1461-1468
Kahru, A., Dubourguier, H.-C. 2009. From ecotoxicology to nanoecotoxicology. Toxicology, 10.1016/j.tox.2009.08.016


Kunagi kohtasin ka netiavarustes artiklit selle kohta, et nanoTiO2 päikesekreemides võib olla kantserogeenne. Kopeerin selle kohta siia terve jupi artiklist:

Here's a excerpt of a post I found on the adverse effects of micronized TiO2:

Many organizations and businesses have perpetuated this assessment of the carcinogenicity of titanium dioxide (ewg.org). However, several studies and study reviews have been used to compile the safety disclaimers for the regulations on the permitted use of titanium dioxide. One such study review took place in Rome, 1969 between the World Health Organization and the Food & Agriculture Organization of the United Nations. Cross species analyses were performed and reviewed for possible toxicity of titanium dioxide. The conference concluded that among the following species: rats, dogs, guinea pigs, rabbits, cats and human males, ingestion of titanium dioxide at varying diet percentages and over long periods of time did not cause absorption of this mineral. Titanium dioxide particulates were not detected in the blood, liver, kidney or urine and no adverse effects were noted from its ingestion. The U.S. Food & Drug Administration (2002) allows for its ingestion, external application including the eye area, and considers it a safe substance for public health. Other epidemiological studies showed that workers exposed to titanium dioxide exhibited no statistically significant relationship between such exposure with lung cancer and respiratory disease, although some cases of pulmonary fibrosis did occur. These studies were conducted in industrial settings where the increased exposure puts these individuals more at risk than the average person.

Titanium dioxide is listed as a safe pigment, with no known adverse effects. It is not listed as a carcinogen, mutagen, teratogen, comedogen, toxin or as a trigger for contact dermatitis in any other safety regulatory publications beside the NIOSH (Antczak, 2001; Physical & Theoretical Chemical Laboratory, Oxford University respectively). It is reasonable to conclude then, that titanium dioxide is not a cancer-causing substance and is generally safe for use in foods, drugs, paints and cosmetics. This does not end the debate, however, as controversy over the safety of one unique form of titanium dioxide still exists.

One form of mineral or mineral extract, including titanium dioxide, that we should be concerned about is ultrafine or nano particles. As technology has advanced, so has its ability to take normal sized particles of minerals and reduce them to sizes never before imagined. While many are praising this new technology, others are warning of its inherent dangers to our bodies. A study by Churg et. al. at the University of British Columbia in their paper "Induction of Fibrogenic Mediators by Fine and Ultrafine Titanium Dioxide in Rat Tracheal Explants" (1999) found that ultrafine particles of the anatase form of titanium dioxide, which are less than 0.1 microns, are pathogenic or disease causing.

Measurements of Mineral Pigment Particles

Coarse : Less than 10 microns
Fine: Less than 2.5 microns
Ultrafine (nanoparticles): Less than 0.1 microns or 100 nanometres

Particle Size and Entry into the Human Body

70 nanometres Alveolar surface of lung
50 nanometres Cells
30 nanometres Central Nervous System
Less than 20 nanometres No data yet
(etcgroup.org)

Kumazawa, et. al. in their study, "Effects of Titanium Ions and Particles on Neutrophil Function and Morphology" concluded that cytotoxicity (danger to the cell) was dependent on the particle size of titanium dioxide. The smaller the particle size, the more toxic it is. This conclusion is relevant to the consumer because of the cosmetics industry's increasing use of micronized pigments in sunscreens and colour cosmetics. Nanoparticles of titanium dioxide are used in sunscreens because they are colourless at that size and still absorb ultraviolet light. Many cosmetic companies are capitalizing on metal oxide nanoparticles. We have seen, however, that if titanium dioxide particles used to act as a sunscreen are small enough, they can penetrate the cells, leading to photocatalysis within the cell, causing DNA damage after exposure to sunlight (Powell, et. al. 1996) The fear is that this could lead to cancer in the skin. Studies with subjects who applied sunscreens with micronized titanium dioxide daily for 2-4 weeks showed that the skin can absorb microfine particles. These particles were seen in the percutaneous layers of the skin under UV light. Coarse or fine particles of titanium dioxide are safe and effective at deflecting and absorbing UV light, protecting the skin, but consumers should avoid using products with micronized mineral pigments, either in sunscreens or colour cosmetics.

As with any health issue, relevant studies must be examined closely to reach balanced conclusions about its impact on our health and well-being. Often, risk determinations are made without considering actual hazards and real-life exposures (Warheit, 2004). The Organic Make-up Co. considers fine or coarse particle sized titanium dioxide and other mineral pigments to be safe according to the studies available and information discussed in this article. Despite repeated requests for micronized pigments in our colour cosmetics, we insist on using only coarse or fine particles of mineral pigments, balancing our need to look beautiful with our more pressing need to stay healthy. With the multitude of cosmetics and chemicals available to us, it is in our best interest to become informed as consumers and make pure, natural and simple choices to protect our health and longevity.


References:
* Antczak, Cosmetics Unmasked. Harper Collins; London:2001
* Blake, et.al. "Application of the Photocatalytic Chemistry of TiO2 to Disinfection and the Killing of Cancer Cells", Separation and Purification Methods; Vol 28 (1) 1999 p.1-50
* Churg, Gilks, Dai, UBC Dept. of Pathology. Am J Physiol Lung Cell Mol Physiol. Vol 277 Issue 5 L975-L982, 1999
* Dunford, et. al. FEBS Letters 418, 87 1997
* Etcgroup.org
* Kamazawa, et.al. "Effects of Titanium Ions and Particles of Neutrophil Function and Morphology". Biomaterials 2002 Sep 23 (17): 3757-64
* Powell, et. al. GUT 38, 390 1996
* Warheit, David "Nanoparticles: Health Impacts?". Materials Today, Feb. 2004
* Witt, Stephen. Director of Technological Support, N. American Refractories Co.