Are engineered nano iron oxide particles safe? an environmental risk assessment by probabilistic exposure, effects and risk modeling

Abstract

Nano iron oxide particles are beneficial to our daily lives through their use in paints, construction materials, biomedical imaging and other industrial fields. However, little is known about the possible risks associated with the current exposure level of engineered nano iron oxides (nano-FeOX) to organisms in the environment. The goal of this study was to predict the release of nano-FeOX to the environment and assess their risks for surface waters in the EU and Switzerland. The material flows of nano-FeOX to technical compartments (waste incineration and waste water treatment plants) and to the environment were calculated with a probabilistic modeling approach. The mean value of the predicted environmental concentrations (PECs) of nano-FeOX in surface waters in the EU for a worst-case scenario (no particle sedimentation) was estimated to be 28 ng/l. Using a probabilistic species sensitivity distribution, the predicted no-effect concentration (PNEC) was determined from ecotoxicological data. The risk characterization ratio, calculated by dividing the PEC by PNEC values, was used to characterize the risks. The mean risk characterization ratio was predicted to be several orders of magnitude smaller than 1 (1.4 × 10). Therefore, this modeling effort indicates that only a very limited risk is posed by the current release level of nano-FeOX to organisms in surface waters. However, a better understanding of the hazards of nano-FeOX to the organisms in other ecosystems (such as sediment) needs to be assessed to determine the overall risk of these particles to the environment.

Environmental risk assessment of engineered nano‐SiO2, nano iron oxides, nano‐CeO2, nano‐Al2O3, and quantum dots

“…The concentrations estimated in the present study are valid for the regional scale, which implies that the PEC values in a local water system might be higher than the predicted values and consequently may underestimate the environmental risk of the considered ENMs. Earlier studies have applied the SSD method to assess the environmental hazards for some of the ENMs covered in the present study, for example, nano-SiO 2 , nano iron oxides, nano-Al 2 O 3 , and nano-CeO 2 (Garner et al 2015;Wang et al 2016aWang et al , 2016b. The PNEC value of nano-SiO 2 predicted in the present study (1665 mg/L) is close to the results presented in the previous study (1028 mg/L) (Wang et al 2016b).…”

“…This dynamic model considers a material input into the environment from 1990 to 2020 and reflects regional differences in waste management (Wang and Nowack ). From previous static models, PEC values are available for nano‐SiO 2 , nano iron oxides, nano‐Al 2 O 3 , nano‐CeO 2 , and quantum dots (Gottschalk et al ; Wang et al , ). The concentrations presented in the present study can be either higher or lower than those from previous studies, depending on the material.…”

“…The PNEC value of nano-SiO 2 predicted in the present study (1665 mg/L) is close to the results presented in the previous study (1028 mg/L) (Wang et al 2016b). The updated PNEC for nano iron oxides is at the same concentration level as in a previous study (Wang et al 2016a). Garner et al (2015) have built SSDs for nano-Al 2 O 3 and nano-CeO 2 and estimated that the PNEC values are 2 to 8 mg/L for nano-Al 2 O 3 and 0.08 to 6 mg/L for nano-CeO 2 .…”

“…The other assessment factor was applied to extrapolate long-term effects from short-term studies. The method of assigning the assessment factor was described in detail in previous studies (Coll et al 2016;Wang et al 2016a) and is based on the REACH guidelines (European Chemicals Agency (2008)). To calculate NOEC values with all uncertainties included, the collected ecotoxicological data were introduced into the model as triangular distributions, which were then divided by 2 assessment factors, to which triangular distributions were also applied in order to consider the uncertainties associated with the assessment factors.…”

Nano-Sized Fe(III) Oxide Particles Starting from an Innovative and Eco-Friendly Synthesis Method

“…The α-Fe 2 O 3 is structurally characterized by a hexagonal unit cell, in which two-thirds of the octahedral sites are occupied by Fe 3+ ions (corundum structure) [2], and orders antiferromagnetically below its Nèel temperature, T N ≈ 955 K. However, at room temperature, it presents a week magnetization, due to slight canting of the magnetic moment with respect to the antiferromagnetic order. It is an n-type semiconductor (Eg = 2.1 eV), and it has been considered for a wide range of applications because it is readily available, non-toxic and an environment-friendly material, hardly affected by changes in oxidation [3][4][5]. If produced in the form of nanoparticles, due to the low toxicity, stability and unique properties, hematite can be considered ideal for applications in a wide range of emerging fields.…”