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(Nano)-Titanium dioxide (Part III): Environmental effects



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Institute of Technology Assessment
of the Austrian Academy of Sciences NNoo.. 003355eenn DDeecceemmbbeerr 22001122
Titanium dioxide (TiO2) has been industrial-
ly produced and used for over 100 years
(see NanoTrust Dossier 033en); this makes
nano-titanium dioxide (nano-TiO2) the best
investigated of all nanomaterials. Its abun-
dance also raises the question of risks to
the environment from TiO2both in its reg-
ular and nano-form. Numerous in-vivo and
in-vitro studies have been conducted to de-
termine the environment-related risks. This
dossier provides a brief overview. Details,
compilations of studies as well as in-depth
risk assessments are available from a num-
ber of international bodies (EU, IARC, OECD,
Environmental effects
of nano-TiO2
As already reported in detail in the Dossier
Environment1, the impacts of nano-TiO2
are the best investigated among nanoma-
terials. Many animals and plants as well
as the media water and soil (aquatic, ter-
restrial) have been studied. One criticism
is that the results of the studies are not com-
parable because the respective NPs (and
therefore their properties) vary from man-
ufacturer to manufacturer2. Moreover, the
presence and distribution of synthetic na-
noparticles in the environment are almost
completely unknown3, with the exception
of a few modeling studies in which environ-
mental concentrations were calculated4; 5.
Nonetheless, experimental approaches pro-
vide evidence for harmful effects both in
aquatic and terrestrial ecosystems, although
such impacts were demonstrable only at
very high doses. An industrial accident,
however, could release such concentrations
of nano-TiO2and pose a risk to algae,
plankton and fishes6. The US Environmen-
tal Protection Agency EPA7has compiled
an overview of research results on TiO2-
NPs on the aquatic environment8; 9:
For algae, which serve as the basis of
marine food chains, values exceeding
30 mg/l are harmful. 30 mg/l photocat-
alytic and 90 mg/l photostable nano-
TiO2impede growth.
For water fleas (Daphnia magna, Fig-
ure 1), which are accepted test organ-
isms and indicators for environmental
impacts, damage was caused by photo-
catalytic particles at concentrations from
5.5 to 10 mg/l (LC50 see also10). For coat-
ed nano-TiO2, an LC50-value of 100 mg/l
was determined.
For fish (rainbow trout, Oncorhynchus
mykiss as an aquatic test organism) an
LC50-value of 100 mg/l photostable
TiO2-NPs was determined. In the case
of chronic exposure to photocatalytic
particles, a value of 0.1 mg/l already led
to oxidative stress and altered organ
structure. The accumulation in the or-
gans, however, apparently does not im-
pair their function (see also11; 12).
Nano-titanium dioxide (nano-TiO2) is the
nanomaterial produced in the greatest
amounts and is already a component in
many products, both in its regular and
nano-scale size. This also makes it the
best-investigated nanoparticle. Many in-
vivo and in-vitro studies have been con-
ducted to test for potential environmen-
tal risks. Nonetheless, the possible long-
term effects remain unknown. Short-term
exposures to high doses showed dam-
age both in aquatic and in terrestrial
ecosystems. No specific regulations for
nano-TiO2are currently in place.
* Corresponding author
(Nano)-Titanium dioxide (Part III):
Environmental effects
Myrtill Simkó*,
René Fries
Figure 1:
The water flea (Daphnia magna)17
NNoo.. 003355eenn DDeecceemmbbeerr 22001122
One study experimentally simulated a run-
ning water system and added photocatalyt-
ic nano-TiO2(5 mg/l water) in order to in-
vestigate the effects on the microbial com-
munities under natural conditions13. Both
TiO2-NPs as well as larger natural agglom-
erates significantly damaged the microor-
ganisms. The authors concluded that the mi-
crobial communities reacted very sensitive-
ly to NP concentrations that can be expect-
ed in the environment. The resulting impacts
on the ecosystem itself remain unknown.
A further study reported on the effect of UV
light on the toxicity of photoactive nano-
TiO2(1 mg/l)14. Laboratory measurements
showed that even the very low UV intensi-
ties that occur near the ocean surface can
trigger significant toxic damage to aquatic or-
ganisms (phytoplankton). The authors there-
fore identify the need to consider the pho-
toactive (toxic) properties of nanomaterials.
It remains unknown how TiO2-NPs behave
along food chains. Does a transfer of the
particles take place from animal to animal
or from plant to animal through food up-
take? A first study shows that this is experi-
mentally possible. Daphnia fed with TiO2-
NPs were subsequently fed to zebra fishes
(Danio rerio) and the particles were found
in the fishes. The long-term effect of such
particles on these fishes and on other food
chains is not known.
Effects on sewage
treatment plants
The issue of accumulation of TiO2-NPs is rel-
evant not only for the environment but also
for sewage treatment plants, where an ac-
cumulation can actually take place. Two stud-
ies4; 5 came to the conclusion that risks for
aquatic organisms through nano-TiO2in
waste streams in all regions considered (USA,
Europe, Switzerland) could not be excluded.
This pertained both to surface waters as well
as to the wastewater in sewage treatment
plants. The calculations are based on a sce-
nario using current estimated values (no ex-
trapolation into the future was undertaken
because the uncertainty of such data was too
high). The simulations involved both a re-
alistic as well as a so-called „worst case sce-
nario” based on generally accepted values
(see Table 1). Since 2006 it is no longer per-
missible to spread sewage sludge on agri-
cultural land. This has minimized soil con-
tamination with nano-TiO2. If this ban did
not exist and sewage sludge was applied on
50 % of such land, this would yield the high-
er values (marked with KS)4in Table 1. The
second study5 simulated material flows for
different regions (Europe, Switzerland and
the US). The data for surface waters and for
treated wastewater represent the actual val-
ues in 2008. In contrast, the data for soils
consider the annual increase in the NP con-
centration and separately treat soils with (KS)
and without (noKS) fertilization with sewage
sludge. This makes the newer simulation
more precise (Table 2). Interestingly, the con-
centrations of nano-TiO2in treated waste-
water and in soils are lower than in the ear-
lier study.
Another study investigated the purification
effect of the sewage treatment facilities in
greater detail. The results show that a good
biological wastewater treatment retains
more than 98 % of the TiO2-NPs from the
wastewater flows and that the use of micro-
filtration is more effective than the common-
ly used settling tanks15. The remaining con-
centration of Ti in the treated wastewater typ-
ically lies between 2 and 20 µg/l.
One study focused on the question of what
effects TiO2-NPs have on those bacterial
colonies in sewage treatment plants that de-
compose nitrogen and phosphorus com-
pounds. Over the short term (1 day), TiO2
concentrations of 1 or 50 mg/l showed no
effects. It required a long-term period (70
days) with a very high TiO2concentration (50
mg/l) to significantly reduce nitrogen decom-
position from 80 % to 24 %. A more detailed
DNA study of the bacterial strains showed
that this was caused by a strongly reduced
microbial diversity16.
Effects on soils
Similar results were obtained in studies on
soil samples from meadows (California,
USA), where TiO2-NPs were applied at dif-
ferent concentrations (0, 0.5, 1.0, and 2.0
mg/g soil) and times (15 days and 60 days)
(see also6). The effects on the natural soil
bacteria communities were investigated. The
authors determined that both amount of mi-
croorganismic biomass and its diversity
changed over time. The impacts were dose-
dependent and already present at the low-
est dose applied (0.5 mg/g soil). The authors
point to model calculations5that predict the
annual amount of TiO2-NPs spread by sew-
age sludge to be 0.09 mg/kg soil, under-
lining the potential risks to the environment.
rs ... realistic scenario
ws ... worst case scenario
KS ... with sewage sludge application
noKS ... without sewage sludge application
Table 1:
Different scenarios for
nano-TiO2concentrations in wastewater, sewage sludge and soil
Study Concentration of nano-TiO2
In treated wastewater
(in µg/l)
In sewage sludge
(in mg/kg)
In soil
(in µg/kg)
MUELLER 200840.7 (rs) to 16 (ws) no data 0.4 (rs) to 4.8 (ws), 120 (KS)
3.5 (Europe)
1.8 (USA)
4.3 (Switzerland)
136 (Europe)
137 (USA)
211 (Switzerland)
Europe (annual input):
1.3 (noKS) to 89 (KS)
USA (annual input):
0.5 (noKS) to 42 (KS)
Switzerland (annual input):
0.3 (noKS)
NNoo.. 003355eenn DDeecceemmbbeerr 22001122
Notes and References
1NanoTrust Dossier, 027en.
2Menard, A., Drobne, D. and Jemec, A., 2011,
Ecotoxicity of nanosized TiO2. Review of in vi-
vo data, Environ Pollut 159(3), 677-84.
3Peralta-Videa, J. R., Zhao, L., Lopez-Moreno,
M. L., de la Rosa, G., Hong, J. and Gardea-
Torresdey, J. L., 2011, Nanomaterials and the
environment: a review for the biennium 2008-
2010, J Hazard Mater 186(1), 1-15.
4Mueller, N. C. and Nowack, B., 2008, Expo-
sure modeling of engineered nanoparticles in
the environment, Environ Sci Technol 42(12),
5Gottschalk, F., Sonderer, T., Scholz, R. W. and
Nowack, B., 2009, Modeled environmental
concentrations of engineered nanomaterials
(TiO(2), ZnO, Ag, CNT, Fullerenes) for differ-
ent regions, Environ Sci Technol 43(24), 9216-
6Zhang, R., Bai, Y., Zhang, B., Chen, L. and Yan,
B., 2012, The potential health risk of titanium
nanoparticles, J Hazard Mater 211-212, 404-
7EPA (U.S. Environmental Protection Agency),
2010, State of the Science Literature Review:
Nano Titanium Dioxide Environmental Matters.
Scientific, Technical, Research, Engineering and
Modeling Support (STREAMS) Final Report, Nr.
EPA/600/R-10/089, August 2010.
8Adams, L. K., Lyon, D. Y., McIntosh, A. and Al-
varez, P. J., 2006, Comparative toxicity of na-
no-scale TiO2, SiO2and ZnO water suspen-
sions, Water Sci Technol 54(11-12), 327-34.
9Hund-Rinke, K. and Simon, M., 2006, Ecotox-
ic effect of photocatalytic active nanoparticles
(TiO2) on algae and daphnids, Environ Sci Pol-
lut Res Int 13(4), 225-32.
10 NanoTrust Dossier 028en.
11 Federici, G., Shaw, B. J. and Handy, R. D.,
2007, Toxicity of titanium dioxide nanoparti-
cles to rainbow trout (Oncorhynchus mykiss):
gill injury, oxidative stress, and other physio-
logical effects, Aquat Toxicol 84(4), 415-30.
12 Ramsden, C. S., Smith, T. J., Shaw, B. J. and
Handy, R. D., 2009, Dietary exposure to tita-
nium dioxide nanoparticles in rainbow trout,
(Oncorhynchus mykiss): no effect on growth,
but subtle biochemical disturbances in the
brain, Ecotoxicology 18(7), 939-51.
13 Battin, T. J., Von der Kammer, F., Weilhartner,
A., Ottofuelling, S. and Hofmann, T., 2009,
Nanostructured TiO2: Transport Behavior and
Effects on Aquatic Microbial Communities un-
der Environmental Conditions, Envir Sci Tech-
nol 43(21), 8098-8104.
14 Miller, R. J., Bennett, S., Keller, A. A., Pease,
S. and Lenihan, H. S., 2012, TiO2nanopar-
ticles are phototoxic to marine phytoplankton,
PLoS One 7(1), e30321.
15 Westerhoff, P., Song, G., Hristovski, K. and Kiser,
M. A., 2011, Occurrence and removal of tita-
nium at full scale wastewater treatment plants:
implications for TiO2nanomaterials, J Environ
Monit 13(5), 1195-203.
16 Zheng, X., Chen, Y. and Wu, R., 2011, Long-
term effects of titanium dioxide nanoparticles
on nitrogen and phosphorus removal from
wastewater and bacterial community shift in
activated sludge, Environ Sci Technol 45(17),
17 Lovern, S. B., Strickler, J. R. and Klaper, R.,
2007, Behavioral and Physiological Changes
in Daphnia magna when Exposed to Nanopar-
ticle Suspensions (Titanium Dioxide, Nano-C60,
and C60HxC70Hx), Envir Sci Technol 41(12),
Conclusions (Parts I to III)
TiO2is a widely distributed substance that is currently incorporated in many different prod-
ucts including sunscreens and foods. This explains why TiO2is so well studied, even if no
long-term studies on nano-TiO2are available. In epidemiological studies, regular TiO2showed
no TiO2-specific effects related to cancer incidence. Nonetheless, based on animal exper-
iments, international bodies have classified this material as “possibly carcinogenic in hu-
mans”. Although specific studies conducted by the FDA clearly point to an extremely low
risk, the remaining uncertainties and discrepancies lead to the recommendation to use cau-
tion when applying nano-TiO2-containing cosmetics to injured skin.
Many studies have been conducted to describe the potential environmental effects of nano-
TiO2. As most of these studies involved extremely high doses, any definitive statements on
the environmentally relevant risks remain speculative. Nonetheless, the consensus is that
small amounts represent a rather low risk to the environment, whereby the long-term ef-
fects with low doses of nano-TiO2remain unclear. There are currently no actually meas-
ured data on environmental exposure; another unclarified issue is how TiO2-NPs behave
in food chains. Whether a transfer of the particles takes place from animal to animal or
from plant to animal through feeding also remains unclear. We have no information about
the effects that the particles may exert over the long term on aquatic and terrestrial ecosys-
tems. This calls for urgent and targeted research in this field.
Owner: Austrian Academy of Sciences; legal person under public law
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Editor: Institute of Technology Assessment (ITA); Strohgasse 45/5, A-1030 Vienna;
Mode of publication: The NanoTrust Dossiers are published irregularly and contain the research
results of the Institute of Technology Assessment in the framework of its research project NanoTrust.
The Dossiers are made available to the public exclusively via the Internet portal “epub.oeaw” :
NanoTrust-Dossier No. 035en, December 2012:
ISSN: 1998-7293
This Dossier is published under the Creative Commons
(Attribution-NonCommercial-NoDerivs 2.0 Austria)
ResearchGate has not been able to resolve any citations for this publication.
Full-text available
Nanoparticulate titanium dioxide (TiO(2)) is highly photoactive, and its function as a photocatalyst drives much of the application demand for TiO(2). Because TiO(2) generates reactive oxygen species (ROS) when exposed to ultraviolet radiation (UVR), nanoparticulate TiO(2) has been used in antibacterial coatings and wastewater disinfection, and has been investigated as an anti-cancer agent. Oxidative stress mediated by photoactive TiO(2) is the likely mechanism of its toxicity, and experiments demonstrating cytotoxicity of TiO(2) have used exposure to strong artificial sources of ultraviolet radiation (UVR). In vivo tests of TiO(2) toxicity with aquatic organisms have typically shown low toxicity, and results across studies have been variable. No work has demonstrated that photoactivity causes environmental toxicity of TiO(2) under natural levels of UVR. Here we show that relatively low levels of ultraviolet light, consistent with those found in nature, can induce toxicity of TiO(2) nanoparticles to marine phytoplankton, the most important primary producers on Earth. No effect of TiO(2) on phytoplankton was found in treatments where UV light was blocked. Under low intensity UVR, ROS in seawater increased with increasing nano-TiO(2) concentration. These increases may lead to increased overall oxidative stress in seawater contaminated by TiO(2), and cause decreased resiliency of marine ecosystems. Phototoxicity must be considered when evaluating environmental impacts of nanomaterials, many of which are photoactive.
Full-text available
The expanding use of titanium dioxide nanoparticles (TiO(2) NPs) in a wide range of fields raises concerns about their potential environmental impacts. However, investigations of the potential effects of TiO(2) NPs on biological nitrogen and phosphorus removal and bacterial community in activated sludge are sparse. This study evaluated the influences of TiO(2) NPs on biological nutrient removal in the anaerobic-low dissolved oxygen (0.15-0.50 mg/L) sequencing batch reactor. It was found that 1 and 50 mg/L TiO(2) NPs had no acute effects on wastewater nitrogen and phosphorus removal after short-term exposure (1 day). However, 50 mg/L TiO(2) NPs (higher than its environmentally relevant concentration) was observed to significantly decrease total nitrogen (TN) removal efficiency from 80.3% to 24.4% after long-term exposure (70 days), whereas biological phosphorus removal was unaffected. Denaturing gradient gel electrophoresis profiles showed that 50 mg/L TiO(2) NPs obviously reduced the diversity of microbial community in activated sludge, and fluorescence in situ hybridization analysis indicated that the abundance of nitrifying bacteria, especially ammonia-oxidizing bacteria, was highly decreased after long-term exposure to 50 mg/L TiO(2) NPs, which was the main reason for the serious deterioration of ammonia oxidation. Further study revealed that 50 mg/L TiO(2) NPs inhibited the activities of ammonia monooxygenase and nitrite oxidoreductase after long-term exposure, but had no significant impacts on the activities of exopolyphosphatase and polyphosphate kinase, and the transformations of intracellular polyhydroxyalkanoates and glycogen, which were consistent with the observed influences of TiO(2) NPs on biological nitrogen and phosphorus removal.
Full-text available
Titanium dioxide nanoparticles increasingly will be used in commercial products and have a high likelihood of entering municipal sewage that flows to centralized wastewater treatment plants (WWTPs). Treated water (effluent) from WWTPs flows into rivers and lakes where nanoparticles may pose an ecological risk. To provide exposure data for risk assessment, titanium concentrations in raw sewage and treated effluent were determined for 10 representative WWTPs that use a range of unit processes. Raw sewage titanium concentrations ranged from 181 to 1233 µg L(-1) (median of 26 samples was 321 µg L(-1)). The WWTPs removed more than 96% of the influent titanium, and all WWTPs had effluent titanium concentrations of less than 25 µg L(-1). To characterize the morphology and presence of titanium oxide nanoparticles in the effluent, colloidal materials were isolated via rota-evaporation, dialysis and lyophilization. High resolution transmission electron microscopy and energy dispersive X-ray analysis indicated the presence of spherical titanium oxide nanoparticles (crystalline and amorphous) on the order of 4 to 30 nm in diameter in WWTP effluents. This research provides clear evidence that some nanoscale particles will pass through WWTPs and enter aquatic systems and offers a methodological framework for collecting and analyzing titanium-based nanomaterials in complex wastewater matrices.
Full-text available
Our laboratory recently reported gut pathology following incidental ingestion of titanium dioxide nanoparticles (TiO(2) NPs) during aqueous exposures in trout, but there are almost no data on dietary exposure to TiO(2) NPs in fish. The aim of this experiment was to observe the sub-lethal effects of dietary exposure to TiO(2) NPs in juvenile rainbow trout (Oncorhynchus mykiss). Stock solutions of dispersed TiO(2) NPs were prepared by sonication without the use of solvents and applied to a commercial trout diet. Fish were exposed in triplicate to either, control (no added TiO(2)), 10, or 100 mg kg(-1) TiO(2) NPs diets for 8 weeks followed by a 2 week recovery period where all fish were fed the control diet. TiO(2) NPs had no impact on growth or nutritional performance, and no major disturbances were observed in red or white blood cell counts, haematocrits, whole blood haemoglobin, or plasma Na(+). Ti accumulation occurred in the gill, gut, liver, brain and spleen during dietary TiO(2) exposure. Notably, some of these organs, especially the brain, did not clear Ti after exposure. The brain also showed disturbances to Cu and Zn levels (statistically significant at weeks 4 and 6; ANOVA or Kruskal-Wallis, P < 0.05) and a 50% inhibition of Na(+)K(+)-ATPase activity during TiO(2) NP exposure. Na(+)K(+)-ATPase activity was unaffected in the gills and intestine. Total glutathione in the gills, intestine, liver and brain were not affected by dietary TiO(2) NPs, but thiobarbituric acid reactive substances (TBARS) showed up to 50% decreases in the gill and intestine. We conclude that TiO(2) NPs behave like other toxic dietary metals where growth rate and haematology can be protected during sub-lethal exposures, but in the case of TiO(2) NPs this may be at the expense of critical organs such as the brain and the spleen.
Full-text available
Due to their large potential for manifold applications, the use of nanoparticles is of increasing importance. As large amounts of nanoparticles may reach the environment voluntarily or by accident, attention should be paid on the potential impacts on the environment. First studies on potential environmental effects of photocatalytic TiO2 nanoparticles have been performed on the basis of widely accepted, standardized test systems which originally had been developed for the characterization of chemicals. The methods were adapted to the special requirements of testing photocatalytic nanoparticles. Suspensions of two different nanoparticles were illuminated to induce their photocatalytic activity. For testing, the growth inhibition test with the green alga Desmodesmus subspicatus and the immobilization test with the daphnid Daphnia magna were selected and performed following the relevant guidelines (algae: ISO 8692, OECD 201, DIN 38412-33; daphnids: ISO 6341, OECD 202, DIN 38412-30). The guidelines were adapted to meet the special requirements for testing photocatalytic nanoparticles. The results indicate that it is principally possible to determine the ecotoxicity of nanoparticles. It was shown that nanoparticles may have ecotoxicological effects which depend on the nature of the particles. Both products tested differ in their toxicity. Product 1 shows a clear concentration-effect curve in the test with algae (EC50: 44 mg/L). It could be proven that the observed toxicity was not caused by accompanying contaminants, since the toxic effect was comparable for the cleaned and the commercially available product. For product 2, no toxic effects were determined (maximum concentration: 50 mg/L). In the tests with daphnids, toxicity was observed for both products, although the concentration effect-curves were less pronounced. The two products differed in their toxicity; moreover, there was a difference in the toxicity of illuminated and non-illuminated products. Both products differ in size and crystalline form, so that these parameters are assumed to contribute to the different toxicities. The concentration-effect curves for daphnids, which are less-pronounced than the curves obtained for algae, may be due to the different test organisms and/or the differing test designs. The increased toxicity of pre-illuminated particles in the tests with daphnids demonstrates that the photocatalytic activity of nanoparticles lasts for a period of time. The following conclusions can be drawn from the test results: (I) It is principally possible to determine the ecotoxicity of (photocatalytic) nanoparticles. Therefore, they can be assessed using methods comparable to the procedures applied for assessing soluble chemicals. (II) Nanoparticles may exert ecotoxicological effects, which depend on the specific nanoparticle. (III) Comparable to traditional chemicals, the ecotoxicity depends on the test organisms and their physiology. (IV) The photocatalytic activity of nanoparticles lasts for a relevant period of time. Therefore, pre-illumination may be sufficient to detect a photocatalytic activity even by using test organisms which are not suitable for application in the pre-illumination-phase. First results are presented which indicate that the topic 'ecotoxicity and environmental effects of nanoparticles' should not be neglected. In testing photocatalytic nanoparticles, there are still many topics that need clarification or improvement, such as the cause for an observed toxicity, the improvement of the test design, the elaboration of a test battery and an assessment strategy. On the basis of optimized test systems, it will be possible to test nanoparticles systematically. If a potential risk by specific photocatalytic particles is known, a risk-benefit analysis can be performed and, if required, risk reducing measures can be taken.
Widespread use of titania nanoparticles (TNPs) has caused a significant release of TNPs into the environment, increasing human exposure to TNPs. The potential toxicity of TNPs has become an urgent concern. Various models have been used to evaluate the toxic effects of TNPs, but the relationship between TNPs' toxicity and physicochemical properties is largely unknown. This review summarizes relevant reports to support the development of better predictive toxicological models and the safe future application of TNPs.
This report presents an exhaustive literature review of data on the effect of nanoparticulate TiO(2) on algae, higher plants, aquatic and terrestrial invertebrates and freshwater fish. The aim, to identify the biologically important characteristics of the nanoparticles that have most biological significance, was unsuccessful, no discernable correlation between primary particle size and toxic effect being apparent. Secondary particle size and particle surface area may be relevant to biological potential of nanoparticles, but insufficient confirmatory data exist. The nanotoxicity data from thirteen studies fail to reveal the characteristics actually responsible for their biological reactivity because reported nanotoxicity studies rarely carry information on the physicochemical characteristics of the nanoparticles tested. A number of practical measures are suggested which should support the generation of reliable QSAR models and so overcome this data inadequacy.
Applications of nanotechnology are touching almost every aspect of modern life. The increased use of engineered nanomaterials (ENMs) in consumer products, chemical and medical equipment, information technology, and energy, among others, has increased the number of publications (informative and scientific) on ENMs. By the 1950s, very few papers were committed to nanomaterials (NMs), but in 2009, more than 80,000 journal articles included the concept nanotechnology. The objective of this review is to compile and analyze publications on NMs in the biennium 2008-2010. This review includes the most recent publications in risk assessment/toxicity, characterization and stability, toxicity, fate and transport of NMs in terrestrial ecosystems, and new ENMs. Carbon nanotubes, metallic, metal oxides and hydroxides nanoparticles, quantum dots, and polystyrene NPs are included.
Engineered nanomaterials (ENM) are already used in many products and consequently released into environmental compartments. In this study, we calculated predicted environmental concentrations (PEC) based on a probabilistic material flow analysis from a life-cycle perspective of ENM-containing products. We modeled nano-TiO(2), nano-ZnO, nano-Ag, carbon nanotubes (CNT), and fullerenes for the U.S., Europe and Switzerland. The environmental concentrations were calculated as probabilistic density functions and were compared to data from ecotoxicological studies. The simulated modes (most frequent values) range from 0.003 ng L(-1) (fullerenes) to 21 ng L(-1) (nano-TiO(2)) for surface waters and from 4 ng L(-1) (fullerenes) to 4 microg L(-1) (nano-TiO(2)) for sewage treatment effluents. For Europe and the U.S., the annual increase of ENMs on sludge-treated soil ranges from 1 ng kg(-1) for fullerenes to 89 microg kg(-1) for nano-TiO(2). The results of this study indicate that risks to aquatic organisms may currently emanate from nano-Ag, nano-TiO(2), and nano-ZnO in sewage treatment effluents for all considered regions and for nano-Ag in surface waters. For the other environmental compartments for which ecotoxicological data were available, no risks to organisms are presently expected.
Industry has already commenced the large-scale production of some nanomaterials. Evidence for toxic effects of engineered nanoparticles (ENP) on model organisms is increasing. However, in order to assess the consequences of environmental hazards, a better understanding is required of the behavior of ENP in aquatic ecosystems and their impact on complex communities. In this research, through experimenting with different TiO(2) nanoparticles in stream microcosms, we have shown that microbial membranes were significantly compromised, even under ambient ultraviolet radiation and nano-TiO(2) concentrations predicted for surface waters. Our results suggest adverse effects are not necessarily only attributable to individual particles smaller than 100 nm but also to low concentrations of larger, naturally agglomerating TiO(2) nanoparticles. Cell membrane damage was more pronounced in free-living cells than in biofilm cells, indicating the protective role of cell encapsulation against TiO(2) nanoparticles. The generation of intracellular reactive oxygen species (ROS) further suggests nano-TiO(2)-induced effects inside the microbial cells. Our findings indicate a high sensitivity of microbial communities to levels of ENP concentration that are to be expected in the environment, with as yet unknown implications for the functioning and health of ecosystems.