In vivo assessment of TiO2 based wear nanoparticles in periprosthetic tissues.

A multimodal approach combining inductively coupled plasma mass spectrometry (ICP-MS), single-particle ICP-MS (spICP-MS), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS) and Raman spectroscopy enabled a deeper insight into the balance between total titanium (Ti), the soluble titanium fraction and titanium dioxide based particle fraction levels in periprosthetic tissues collected from patients undergoing revision surgery. Hydrofluoric acid usage in the sample digestion allowed for complete digestion of TiO2 particles, thus enabling accurate estimation of total Ti levels. The TiO2 fraction represents 38-94% of the titanium load in the six samples where particles were detected, and the fraction is present mainly in samples from patients with aseptically loosened total hip arthroplasty. Further attention was given to this fraction determining the elemental composition, particle count, particle size and modification of TiO2. The spICP-MS analysis confirmed the presence of the TiO2-derived (nano)particles (NPs) with a 39- to 187-nm median size and particle count up to 2.3 × 1011 particles per gram of tissue. On top of that, the SEM-EDS confirmed the presence of the TiO2 nanoparticles with 230-nm median size and an anatase crystal phase was determined by Raman spectroscopy. This study presents a novel multimodal approach for TiO2 particle determination and characterization in tissue samples and is the first in vivo study of this character.

Foraging animal origin food samples as passive indicators of dioxin-like POPs contamination in industry sites: Method development, characterisation and risk assessment.

Titanium dioxide (TiO2) is an important industrial chemical, and studies suggest its major production route - the chloride process could lead to the generation of unintentional dl-POPs. However, no relevant studies assessed the occurrence of dl-POPs associated with TiO2 production in the industrial zones, which is mostly due to the ultra-trace level distribution of these compounds in environmental compartments. The present study explored the novel possibility of utilising foraging animal-origin foods as sensitive indicators for addressing this challenge and generated a globally beneficial dataset by assessing the background levels of dl-POPs in the vicinity of a TiO2 production house in Southern India. Systematic sampling of foraging cow's milk and free-ranging hen's eggs was carried out from the study site, and the dl-POPs assessments were conducted utilising an in-house developed cost-effective GC-MS/MS-based analytical methodology. The median dl-POPs levels in milk and egg samples were about 3 times higher than the control samples collected from farm-fed animals and retail markets. The contaminant loads in the foraging animal-origin food samples were further traced to their presence in environmental compartments of soil and sediment and admissible degree of correlations were observed in congener fingerprints. Elevated health risks were inferred for the population in the industrial zones with weekly intakes weighing about 0.15-17 times the European Food Safety Authority-assigned levels. The consumption of foraging cow's milk was observed to have a higher contribution towards the hazard indices and cancer risk estimates and were significantly higher (p < 0.05) for children. The study also presents a critical validation of the GC-MS/MS-based method for the purpose of regulatory monitoring of dl-POPs, which could be of practical significance in economies in transition.

Assessment of TiO2 (nano)particles migration from food packaging materials to food simulants by single particle ICP-MS/MS using a high efficiency sample introduction system.

TiO2 is the most widely used white pigment in plastics and food packaging industry, thus the question of its migration towards food and hence the impact on consumers is raised. Since recent research indicate its potential toxicity, it is necessary to study TiO2 contamination as a consequence of food storage. For this purpose, plastic containers from commercially-available dairy products and custom-made TiO2-spiked polypropylene materials were put in contact with 50% (v/v) ethanol and 3% (w/v) acetic acid, which were used here as food simulants. The migration assays were carried out under standard contact conditions of packaging use (as recommended by Commission Regulation (EU) N° 10/2011 for food contact migration testing), and under conditions of extreme mechanical degradation of the packaging. The TiO2 (nano)particles released in the food simulants were analysed by single particle inductively coupled plasma-tandem mass spectrometry in mass-shift mode and using a high efficiency sample introduction system (APEX™ Ω) to avoid matrix effects from food simulants. For the dairy product containers and for the spiked polypropylene, results showed release of TiO2 particles of rather large sizes (average size: 164 and 175 nm, respectively) under mechanical degradation conditions, i.e. when the polymeric structure is damaged. The highest amounts of TiO2 were observed in 50% ethanol after 10 days of storage at 50 °C (0.62 ng cm-2) for the dairy product containers and after 1 day of storage at 50 °C (0.68 ng cm-2) for the spiked polypropylene. However, the level of Ti released in particle form was very small compared to the total Ti content in the packaging and far below the acceptable migration limits set by European legislation. Release under standard contact conditions of use of the container was not measurable, thus the migration of TiO2 particles from this packaging to dairy products among storage is expected to be negligible.

Carcinogenic assessment of cobalt-containing alloys in medical devices or cobalt in occupational settings: A systematic review and meta-analysis of overall cancer risk from published epidemiologic studies.

In 2020, the European Commission up-classified pure cobalt metal to a Category 1B hazard, based primarily on data from rodent inhalation carcinogenicity studies of metallic cobalt. The European Commission review did not evaluate cobalt-containing alloys in medical devices, which have very different properties vs. pure cobalt metal and did not include a systematic epidemiologic review. We performed a systematic review and meta-analysis of published, peer-reviewed epidemiologic studies evaluating the association between overall cancer risk and exposure to orthopedic implants containing cobalt alloys or cobalt particulates in occupational settings. Study-specific estimates were pooled using random-effects models. Analyses included 20 papers on orthopedic implants and 10 occupational cohort papers (~1 million individuals). The meta-analysis summary estimates (95% confidence intervals) for overall cancer risk were 1.00 (0.96-1.04) overall and 0.97 (0.94-1.00) among high-quality studies. Results were also similar in analyses stratified by type of exposure/data sources (occupational cohort, implant registry or database), comparators (general or implant population), cancer incidence or mortality, follow-up duration (latency period), and study precision. In conclusion, meta-analysis found no association between exposure to orthopedic implants containing cobalt alloys or cobalt particulates in occupational settings and overall cancer risk, including an analysis of studies directly comparing metal-on-metal vs. non-metal-on-metal implants.

Assessment of Elemental Components in Atmospheric Particulate Matter from a Typical Mining City, Central China: Size Distribution, Source Characterization and Health Risk.

Atmospheric particulate matters in nine size fractions were sampled at Huangshi city, Hubei province. Elemental concentrations occurred unimodal size distribution for Zn, Pb and Ni, dimodal distribution for Ca, S, Fe and Ti, and trimodal distribution for Cl, K, Mn, Cu and Cr. Enrichment factor and principal component analysis identified the main sources from crustal material, biomass burning, waste incineration, vehicular and industrial emission. As for the non-carcinogenic health risk through inhalation, there were certain potential risks for Mn and Sb for children, and Pb for children and adults in PM2.5. It showed certain potential risks for Mn, Sb and Pb for children and adults in PM10. As for the carcinogenic health risk through inhalation, Cr in PM2.5 and Ni, Co and Cr in PM10 indicated unacceptable risk for children and adults. Meanwhile, Co and Ni in PM2.5 represented acceptable risk for children.

Enzymatic hydrolysis as a sample pre-treatment for titanium dioxide nanoparticles assessment in surimi (crab sticks) by single particle ICP-MS.

A reliable sample pre-treatment based on enzymatic hydrolysis has been fully optimized and validated for TiO2 NPs isolation and determination/characterization in surimi (crab sticks). Efficient extractions have been found when using a pancreatin/lipase mixture at pH 7.4 and 37 °C for 12 h under continuous stirring. The proposed sample pre-treatment procedure has been found not to change TiO2 NPs size distribution, therefore guaranteeing TiO2 NPs integrity. TiO2 NPs determination (TiO2 NPs concentration) and TiO2 NPs characterization (size distribution) were assessed by single-particle inductively coupled plasma mass spectrometry (sp-ICP-MS) working with dwell times in the microsecond range (high frequency of data acquisition). Method validation was performed for TiO2 NPs concentrations and TiO2 NPs sizes. Good repeatability (25% and 8% for TiO2 NPs concentration and TiO2 NPs most frequent size), and sensitivity (limit of detection of 5.28 × 105 NPs g-1for TiO2 NPs concentrations, and 31.3-37.1 nm for TiO2 NPs size) were obtained. Accuracy, calculated through analytical recovery was adequate. Recoveries for TiO2 NPs standards of 50 and 100 nm were 108 ±â€¯5 and 105 ±â€¯4%, respectively. The proposed methodology was applied to several surimi samples for assessing TiO2 NPs concentrations and size distribution. Some surimi samples were found to contain TiO2 NPs (concentrations from 1.40 × 107 to 1.19 × 109 NPs g-1). TiO2 NPs size distributions were very different among the samples, and some of them showed wide size ranges (the most frequent size varied from 53.8 to 62.1 nm; whereas, the mean size values were within the 73.4-217.5 nm range).

Assessment of intake of copper and lead by sheep grazing on a shooting range for small arms: a case study.

The Norwegian Armed Forces' shooting ranges contain contamination by metals such as lead (Pb) and copper (Cu) and are often used as grazing pastures for livestock. To determine whether the sheep were at risk from grazing at a shooting range in Nord-Trøndelag (the Leksdalen shooting field), a study was conducted wherein the aim was to determine the amount of soil the sheep were eating, the accumulation of Cu and Pb in the livers of lambs grazing on the shooting ranges, and the accumulation of Pb and Cu in the grass. The grazing behavior of the sheep was mapped using GPS tracking and wildlife cameras. Soil, grass, feces, and liver samples were collected. All the samples were analyzed for Pb, Cu, and molybdenum (Mo), and soil and feces were also analyzed for titanium (Ti). Mean concentrations in grass, soil, feces, and liver was 41-7189, 1.3-29, 4-5, and 0.3 mg/kg Pb, respectively, and 42-580, 4.2-11.9, 19-23, and 273 mg/kg Cu, respectively. The soil ingestion rate was calculated using Ti in feces and soil. From these results, the theoretical dose of Cu and Pb ingested by grazing sheep was calculated. The soil ingestion rate was found to be 0.1-0.4%, significantly lower than the soil ingestion rate of 5-30% usually used for sheep. Little or no accumulation of Cu and Pb in the grass was found. There was no difference between the metal concentrations in the washed and unwashed grass. According to the calculated dose, the sheep were at little or no risk of acute or chronic Pb and Cu poisoning from grazing on the Leksdalen shooting range. The analysis of liver samples showed that lambs grazing on the shooting range did not have higher levels of Cu or Pb than lambs grazing elsewhere. None of the lambs had concentrations of Cu or Pb in their livers indicating poisoning.

Set of Enzymatic Bioassays for Assessment of Soil Contamination.

A concept of the comprehensive assessment of soil contamination is proposed. According to it, the conclusion regarding the presence of toxic substances in the analyzed sample is based on the inhibition of enzymatic reactions responsible for various functions of a living organism, such as luminescence, respiration, etc. These functions are taken as test functions in classical bioassays with the use of living objects (luminous bacteria, daphnia, algae, and others). The regularities of the impact of different classes of toxicants on the activity of particular enzymes or coupled oligo-enzyme chains have been established. These enzyme reactions are selected as potential test objects: markers of contamination. Three enzyme systems with the maximal sensitivity to different classes of toxicants have been chosen for the set of enzymatic bioassays: butyrylcholinesterase, NAD(P)H:FMN-oxidoreductase + luciferase, and lactate dehydrogenase + NAD(P)H:FMN-oxidoreductase + luciferase. The possibility to use enzymes instead of living organisms in the bioassay of natural complex systems has been shown.

Soil ingestion rates for children under 3 years old in Taiwan.

Soil and dust ingestion rates by children are among the most critical exposure factors in determining risks to children from exposures to environmental contaminants in soil and dust. We believe this is the first published soil ingestion study for children in Taiwan using tracer element methodology. In this study, 66 children under 3 years of age were enrolled from Taiwan. Three days of fecal samples and a 24-h duplicate food sample were collected. The soil and household dust samples were also collected from children's homes. Soil ingestion rates were estimated based on silicon (Si) and titanium (Ti). The average soil ingestion rates were 9.6±19.2 mg/day based on Si as a tracer. The estimated soil ingestion rates based on Si did not have statistically significant differences by children's age and gender, although the average soil ingestion rates clearly increased as a function of children's age category. The estimated soil ingestion rates based on Si was significantly and positively correlated with the sum of indoor and outdoor hand-to-mouth frequency rates. The average soil ingestion rates based on Si were generally lower than the results from previous studies for the US children. Ti may not be a suitable tracer for estimating soil ingestion rates in Taiwan because the Ti dioxide is a common additive in food. To the best of our knowledge, this is the first study that investigated the correlations between soil ingestion rates and mouthing behaviors in Taiwan or other parts of Asia. It is also the first study that could compare available soil ingestion data from different countries and/or different cultures. The hand-to-mouth frequency and health habits are important to estimate the soil ingestion exposure for children. The results in this study are particularly important when assessing children's exposure and potential health risk from nearby contaminated soils in Taiwan.

Environmental and human health assessment of life cycle of nanoTiO2 functionalized porcelain stoneware tile.

Recently, there has been a rise in the interest in nanotechnology due to its enormous potential for the development of new products and applications with higher performance and new functionalities. However, while nanotechnology might revolutionize a number of industrial and consumer sectors, there are uncertainties and knowledge gaps regarding toxicological effects of this emerging science. The goal of this research concerns the implementation into Life Cycle Assessment (LCA) of preliminary frameworks developed to evaluate human toxicity and exposure factors related to the potential nanoparticle releases that could occur during the life cycle steps of a functionalized building material. The present LCA case study examines the ecodesign of nanoTiO2 functionalized porcelain stoneware tile production. The aim of this investigation is to manufacture new eco-friendly products in order to protect human health and ecosystem quality and to offer the market, materials with higher technological properties obtained by the addition of specific nanomaterials.

Probabilistic environmental risk assessment of five nanomaterials (nano-TiO2, nano-Ag, nano-ZnO, CNT, and fullerenes).

The environmental risks of five engineered nanomaterials (nano-TiO2, nano-Ag, nano-ZnO, CNT, and fullerenes) were quantified in water, soils, and sediments using probabilistic Species Sensitivity Distributions (pSSDs) and probabilistic predicted environmental concentrations (PECs). For water and soil, enough ecotoxicological endpoints were found for a full risk characterization (between 17 and 73 data points per nanomaterial for water and between 4 and 20 for soil) whereas for sediments, the data availability was not sufficient. Predicted No Effect Concentrations (PNECs) were obtained from the pSSD and used to calculate risk characterization ratios (PEC/PNEC). For most materials and environmental compartments, exposure and effect concentrations were separated by several orders of magnitude. Nano-ZnO in freshwaters and nano-TiO2 in soils were the combinations where the risk characterization ratio was closest to one, meaning that these are compartment/ENM combinations to be studied in more depth with the highest priority. The probabilistic risk quantification allows us to consider the large variability of observed effects in different ecotoxicological studies and the uncertainty in modeled exposure concentrations. The risk characterization results presented in this work allows for a more focused investigation of environmental risks of nanomaterials by consideration of material/compartment combinations where the highest probability for effects with predicted environmental concentrations is likely.

Release of nanomaterials from solid nanocomposites and consumer exposure assessment - a forward-looking review.

The European chemical legislation requires manufacturers and importers of chemicals to do consumer exposure assessment when the chemical has certain hazards associated to it (e.g. explosive, carcinogenicity, and hazardous to the aquatic environment), but the question is how this obligation can be met in light of the scientific uncertainty and technical challenges related to exposure assessment of nanomaterials. In this paper, we investigate to what extent the information and data in the literature can be used to perform consumer exposure assessment according to the REACH requirements and we identify and discuss the key data needs and provide recommendations for consumer exposure assessment of nanomaterials. In total, we identified 76 studies of relevance. Most studies have analyzed the release of Ag and TiO2 from textiles and paints, and CNT and SiO2 from nanocomposites. Less than half of the studies report their findings in a format that can be used for exposure assessment under REACH, and most do not include characterization of the released particles. Although inhalation, dermal, and oral exposures can be derived using the guidelines on how to complete consumer exposure assessments under REACH, it is clear that the equations are not developed to take the unique properties of nanomaterials into consideration. Future research is therefore needed on developing more generalized methods for representing nanomaterial release from different product groups at relevant environmental conditions. This includes improving the analytical methods for determining nanomaterial alteration and transformation, as well as quantification, which could subsequently lead to more nano-specific consumer exposure assessment models.

Monte Carlo simulations of the transformation and removal of Ag, TiO2, and ZnO nanoparticles in wastewater treatment and land application of biosolids.

The use of nano-enabled materials in industry and consumer products is increasing rapidly and with it, the more imperative it becomes to understand the consequences of such materials entering the environment during production, use or disposal. The novel properties of engineered nanomaterials (ENMs) that make them desirable for commercial applications also present the possibility of impacting aquatic and terrestrial environments in ways that may differ from materials in bulk format. Modeling techniques are needed to proactively predict the environmental fate and transport of nanomaterials. A model for nanoparticle (NP) separation and transformation in water treatment was parameterized for three metal and metal-oxide NPs. Functional assays to determine NP specific distribution and transformation were used to parameterize the model and obtain environmentally relevant concentrations of NPs and transformation byproducts leaving WWTPs in effluent and biosolids. All three NPs were predicted to associate >90% with the solid phase indicating significant accumulation in the biosolids. High rates of transformation for ZnO and Ag NPs resulted in ~97% transformation of the NPs that enter the plant despite differences in transformation rate in aerobic versus anaerobic environments. Due to high insolubility and negligible redox transformation, the only process predicted to impact TiO2 NP fate and transport in WWTPs was distribution between the solid and liquid phases. Subsequent investigation of ZnO NP species fate and transport when land applied in biosolids indicated that steady state concentrations of ZnO phases would likely be achieved after approximately 150days under loading conditions of biosolids typical in current practice.

Valorization of titanium metal wastes as tanning agent used in leather industry.

The development of new tanning agents and new technologies in the leather sector is required to cope with the increasingly higher environmental pressure on the current tanning materials and processes such as tanning with chromium salts. In this paper, the use of titanium wastes (cuttings) resulting from the process of obtaining highly pure titanium (ingots), for the synthesis of new tanning agent and tanning bovine hides with new tanning agent, as alternative to tanning with chromium salts are investigated. For this purpose, Ti waste and Ti-based tanning agent were characterized for metal content by inductively coupled plasma mass spectrometry (ICP-MS) and chemical analysis; the tanned leather (wet white leather) was characterized by Scanning Electron Microscope/Energy Dispersive Using X-ray (Analysis). SEM/EDX analysis for metal content; Differential scanning calorimetric (DSC), Micro-Hot-Table and standard shrinkage temperature showing a hydrothermal stability (ranged from 75.3 to 77°C) and chemical analysis showing the leather is tanned and can be processed through the subsequent mechanical operations (splitting, shaving). On the other hand, an analysis of major minor trace substances from Ti-end waste (especially vanadium content) in new tanning agent and wet white leather (not detected) and residue stream was performed and showed that leachability of vanadium is acceptable. The results obtained show that new tanning agent obtained from Ti end waste can be used for tanning bovine hides, as eco-friendly alternative for chrome tanning.

Assessment of solar driven TiO2-assisted photocatalysis efficiency on amoxicillin degradation.

The objective of this work was to evaluate the efficiency of a solar TiO2-assisted photocatalytic process on amoxicillin (AMX) degradation, an antibiotic widely used in human and veterinary medicine. Firstly, solar photolysis of AMX was compared with solar photocatalysis in a compound parabolic collectors pilot scale photoreactor to assess the amount of accumulated UV energy in the system (Q UV) necessary to remove 20 mg L(-1) AMX from aqueous solution and mineralize the intermediary by-products. Another experiment was also carried out to accurately follow the antibacterial activity against Escherichia coli DSM 1103 and Staphylococcus aureus DSM 1104 and mineralization of AMX by tracing the contents of dissolved organic carbon (DOC), low molecular weight carboxylate anions, and inorganic anions. Finally, the influence of individual inorganic ions on AMX photocatalytic degradation efficiency and the involvement of some reactive oxygen species were also assessed. Photolysis was shown to be completely ineffective, while only 3.1 kJUV L(-1) was sufficient to fully degrade 20 mg L(-1) AMX and remove 61% of initial DOC content in the presence of the photocatalyst and sunlight. In the experiment with an initial AMX concentration of 40 mg L(-1), antibacterial activity of the solution was considerably reduced after elimination of AMX to levels below the respective detection limit. After 11.7 kJUV L(-1), DOC decreased by 71%; 30% of the AMX nitrogen was converted into ammonium and all sulfur compounds were converted into sulfate. A large percentage of the remaining DOC was in the form of low molecular weight carboxylic acids. Presence of phosphate ions promoted the removal of AMX from solution, while no sizeable effects on the kinetics were found for other inorganic ions. Although the AMX degradation was mainly attributed to hydroxyl radicals, singlet oxygen also plays an important role in AMX self-photosensitization under UV/visible solar light.

Valorisation of waste ilmenite mud in the manufacture of sulphur polymer cement.

This paper reports the preparation of sulphur polymer cements (SPCs) incorporating waste ilmenite mud for use in concrete construction works. The ilmenite mud raw material and the mud-containing SPCs (IMC-SPCs) were characterised physico-chemically and radiologically. The optimal IMC-SPC mixture had a sulphur/mud ratio (w/w) of 1.05 (mud dose 20 wt%); this cement showed the greatest compressive strength (64 MPa) and the lowest water absorption coefficient (0.4 g cm(-2) at 28 days). Since ilmenite mud is enriched in natural radionuclides, such as radium isotopes (2.0·10(3) Bq kg(-1)(228)Ra and 5.0·10(2) Bq kg(-1)(226)Ra), the IMC-SPCs were subjected to leaching experiments, which showed their environmental impact to be negligible. The activity concentration indices for the different radionuclides in the IMC-SPCs containing 10% and 20% ilmenite mud met the demands of international standards for materials used in the construction of non-residential buildings.

Assessment of the contribution of electron microscopy to nanoparticle characterization sampled with two cascade impactors.

This study assessed the contribution of electron microscopy to the characterization of nanoparticles and compared the degree of variability in sizes observed within each stage when sampled by two cascade impactors: an Electrical Low Pressure Impactor (ELPI) and a Micro-Orifice Uniform Deposit Impactor (MOUDI). A TiO(2) nanoparticle (5 nm) suspension was aerosolized in an inhalation chamber. Nanoparticles sampled by the impactors were collected on aluminum substrates or TEM carbon-coated copper grids using templates, specifically designed in our laboratories, for scanning and transmission electron microscopy (SEM, TEM) analysis, respectively. Nanoparticles were characterized using both SEM and TEM. Three different types of diameters (inner, outer, and circular) were measured by image analysis based on count and volume, for each impactor stage. Electron microscopy, especially TEM, is well suited for the characterization of nanoparticles. The MOUDI, probably because of the rotation of its collection stages, which can minimize the resuspension of particles, gave more stable results and smaller geometric standard deviations per stage. Our data suggest that the best approach to estimate particle size by electron microscopy would rely on geometric means of measured circular diameters. Overall, the most reliable data were provided by the MOUDI and the TEM sampling technique on carbon-coated copper grids for this specific experiment. This study indicates interesting findings related to the assessment of impactors combined with electron microscopy for nanoparticle characterization. For future research, since cascade impactors are extensively used to characterize nano-aerosol exposure scenarios, high-performance field emission scanning electron microscopy (FESEM) should also be considered.

Exposure assessment of workplaces manufacturing nanosized TiO2 and silver.

With the increased production and widespread use of nanomaterials, human and environmental exposure to nanomaterials is inevitably increasing. Therefore, this study monitored the possible exposure to nanoparticles at workplaces that manufacture nano-TiO(2) and nano-silver. To estimate the potential exposure of workers, personal sampling, area monitoring, and real-time monitoring using a scanning mobility particle sizer (SMPS) and dust monitor were conducted at workplaces where the workers handle nanomaterials. The gravimetric concentrations of TiO(2) ranged from 0.10 to 4.99 mg/m(3), which were lower than the occupational exposure limit 10 mg/m(3) set by the Korean Ministry of Labor or American Conference of Governmental Industrial Hygienists (ACGIH). Meanwhile, the silver metal concentrations ranged from 0.00002 to 0.00118 mg/m(3), which were also lower than the silver dust 0.1 mg/m(3) and silver soluble compound 0.01 mg/m(3) occupational exposure limits set by the ACGIH. The particle number concentrations at the nano-TiO(2) manufacturing workplaces ranged from 11,418 to 45,889 particles/cm(3) with a size range of 15-710.5 nm during the reaction, although the concentration decreased to 14,000 particles/cm(3) when the reaction was stopped. The particle concentrations at the TiO(2) manufacturing workplaces increased during the reactor and vacuum pump operations, and during the collection of the synthesized TiO(2) particles. Similarly, the particle concentrations at the silver nanoparticle manufacturing workplaces increased when the sodium citrates were weighed or reacted with the silver nitrates, and during the cleaning of the workplace. The number of silver nanoparticles in the samples obtained from the workplace manufacturing silver nanoparticles using induced coupled plasma ranged from 57,789 to 2,373,309 particles/cm(3) inside the reactor with an average size of 20-30 nm and 535-25,022 particles/cm(3) with a wide range of particle sizes due to agglomeration or aggregation after the release of nanoparticles into the workplace air. In contrast, the silver nanoparticles manufactured by the wet method ranged from 393 to 3526 particle/cm(3) with an average size of 50 nm. Thus, when taken together, the TiO(2) and silver nanoparticle concentrations were relatively lower than existing occupational exposure limits.

An assessment of the fate, behaviour and environmental risk associated with sunscreen TiO2 nanoparticles in UK field scenarios.

The fate of Ti was examined in an activated sludge plant serving over 200,000 people. These studies revealed a decrease of 30 to 3.2 µg/L of Ti < 0.45 µm from influent to effluent and a calculated Ti presence of 305 mg/kg DW in wasted sludge. Thus, using sludge as a fertiliser would result in a predicted deposition of up to 250 mg/m² of Ti to soil surfaces using a recommended maximal agricultural application rate. Given the major use of TiO2 in many industrial and domestic applications where loss to the sewer is possible, this measured Ti was presumed to have been largely TiO2, a proportion of which will be nanoparticle sized. To assess the behaviour of engineered nanoparticle (ENP) TiO2 in sewage and toxicology studies, Optisol (Oxonica Materials Ltd) and P25 (Evonik Industries AG), which are representative of forms used in sunscreen and cosmetic products, were used. These revealed a close association of TiO2 ENPs with activated sludge. Using commercial information on consumption, and removal rates for sewage treatment, predictions were made for river water concentrations for sunscreen TiO2 ENPs for the Anglian and Thames regions in Southern England. The highest predicted value from these exercises was 8.8 µg/L for the Thames region in which it was assumed that one in four people used the recommended application of sunscreen during a low flow (Q95) period. Ecotoxicological studies using potentially vulnerable species indicated that 1000 µg/L TiO2 ENP did not affect the viability of a mixed community of river bacteria in the presence of UV light. Direct exposure to TiO2 ENPs did not impair the immuno-effectiveness of earthworm coelomocyte cells at concentrations greatly above those predicted for sewage sludge.

Nanoparticles-containing spray can aerosol: characterization, exposure assessment, and generator design.

This is the first report demonstrating that a commercially available household consumer product produces nanoparticles in a respirable range. This report describes a method developed to characterize nanoparticles that were produced under typical exposure conditions when using a consumer spray product. A well-controlled indoor environment was simulated for conducting spray applications approximating a human exposure scenario. Results indicated that, while aerosol droplets were large with a count median diameter of 22 µm during spraying, the final aerosol contained primarily solid TiO(2) particles with a diameter of 75 nm. This size reduction was due to the surface deposition of the droplets and the rapid evaporation of the aerosol propellant. In the breathing zone, the aerosol, containing primarily individual particles (>90%), had a mass concentration of 3.4 mg/m(3), or 1.6 × 10(5) particles/cm(3), with a nanoparticle fraction limited to 170 µg/m(3), or 1.2 × 10(5) particles/cm(3). The results were used to estimate the pulmonary dose in an average human (0.075 µg TiO(2) per m(2) alveolar epithelium per minute) and rat (0.03 µg TiO(2)) and, consequently, this information was used to design an inhalation exposure system. The system consisted of a computer-controlled solenoid ''finger'' for generating constant concentrations of spray can aerosols inside a chamber. Test results demonstrated great similarity between the solenoid ''finger''-dispersed aerosol compared to human-generated aerosol. Future investigations will include an inhalation study to obtain information on dose-response relationships in rats and to use it to establish a No Effect Exposure Level for setting guidelines for this consumer product.