Journal of Hazardous, Toxic, and Radioactive Waste

The aim of this article is to evaluate, using available direct and secondary data, the risks to human health and the environment within nanotechnologies research in Mexico. The argument is advanced in four sections. The first illustrates the implications of the risks posed by nanoparticles and nanomaterials to workers, consumers, and the environment. Next, to provide context, is a review of the state of nanotechnologies development in Mexico. This is followed by an outline of the methodology employed, where two protocols were used: The first entailed the creation of a database containing all articles on nanotechnologies published by Mexican authors over a 12-year period and then searching for key terms associated to the risks of nanomaterials; the second protocol involved a web-based search to identify all researchers working in this area. Finally, the results are presented with the conclusion that the subject of risks is, essentially, absent from nanotechnologies research in Mexico.

The Brazilian government, like many other countries, promotes the development of nanotechnology as a strategic area to encourage competitiveness. This paper analyzes the current scenario of nanotechnology in Brazil and the initial intention to legislate to regulate the development and/or certain aspects of commercialization of nanotechnology.

Engineered nanomaterials have been incorporated into thousands of commercial products that are widely used by consumers and industry. Studies show that nanomaterials can be leached from such products, providing a route of entry into the environment. Toxic effects from nanomaterials may differ significantly based on their structure, functional groups, characteristics of the environmental matrix at the time of exposure, and the transformation of the nanomaterials once released into the environment. Consequently, traditional risk assessment models for conventional chemicals may not apply. Currently, engineered nanomaterials are not regulated as hazardous wastes, but the potential for significant negative human or environmental effects should not be ignored. The authors suggest that existing Resources Conservation and Recovery Act (RCRA) regulations could be modified to include categories for engineered nanomaterials. Given the ubiquitous nature of nanoenabled products, some regulatory action is required even before complete risk assessments can be determined.

Nanomaterials (NMs) present some interesting properties that may be tailored; for this reason, they are being used in different fields, which leads to their entry into the environment, whether by normal use or intentional delivery. Once in water and sediments, they undergo different transformations that might be difficult to predict. NMs are also difficult to characterize because the methods for this are recently developed. Currently, the most plausible approach is to combine separation and measurement techniques; one of the most versatile integrations is field-flow fractionation with inductively coupled plasma mass spectrometry (ICP–MS) or ICP optical emission spectrometry. In the same way, toxicity assays must be adapted to these emerging contaminants because they behave neither as chemical compounds nor their bulk counterparts, which produces different results. Nevertheless, several adverse effects of NMs exposure on organisms have been reported, including DNA damage, mortality, oxidative stress, and growth reduction. However, the majority of these studies utilized acute laboratory exposure, whereas in a real ecosystem, organisms are more likely to experience chronic exposure conditions to numerous NMs and a biomagnification effect should be expected through the trophic chain. Despite the lack of sufficient literature, the present review attempts to link various compartmentalization aspects of NMs, their physical properties, and their toxicity in surface water and sediments.

The rapid growth in the cosmetic industry across the world is mainly due to the application of nanoingredients in cosmetics to enhance their properties and invention of new nanomolecules. Also, the weaker regulations on the application of nanoparticles as cosmetic ingredients and no safety assessment of cosmetics before release into the market has led to uncontrolled production and usage. Unavoidable release of a considerable amount of cosmetic nanoparticles into wastewater introduces them into the environment via treated wastewater effluent and sludge. This paper briefly gives the information about behavior of cosmetic nanomaterials, mainly titanium dioxide (${\mathrm{TiO}}_2$) and fullerenes (C60), within the wastewater-treatment plant and current research on their characterization and toxicity. Considering the current analytical methods for evaluating the behavior of these nanomaterials in the wastewater, there is still a need to advance these technologies. Furthermore, a better understanding and modeling of nanomaterials’ fate in wastewater-treatment plants is essential for effectively predicting their impacts on the receiving environment.

Nanotechnologies form a field of research that is still emerging with major gaps in knowledge regarding the behavior and potential toxicological risks of engineered nanoparticles (ENPs) in soils. While most of the studies are conducted in porous media (quartz and glass beads) and culture media, less frequently are the studies carried out in natural soils. However, the complex interactions occurring in soils, mediated by both soil components and soil organisms, are essential in bioavailability processes. Therefore, this paper is intended to highlight particularly the bioavailability of ENPs in soils. The potential release pathways of ENPs to soils are described and are faced with a lack of specific regulation and definitive nomenclature. This paper reviews a number of studies regarding ENP toxicological bioavailability on microorganisms and microfauna, mesofauna, and macrofauna inhabiting the soil, as well as on soil-plant systems. The paper especially discusses ENP behavior in soils that affect ENP bioavailability to the edaphic biota. Particular attention is paid to the factors regulating these processes [i.e., (1) ENP-dependent factors, (2) soil properties, and (3) soil components], focusing on organic matter.

Industrial revolution has led to the introduction of innumerable contaminants into the environment via industrial, agricultural, and household applications. In particular, engineered nanoparticles (ENPs), which are emerging in the natural environment and being transported in the environment, may have a significant effect on ecosystems, even though they may only be present at low concentrations. Nanotechnology is going to play a major role which will be responsible for the release of ENPs in the environmental matrices and thus has led to increased focus on environmental research for the betterment of human society. Despite widespread applications of ENPs, in recent years, their hazardous effects on the air, water, soil, and sediments have been studied, which directly impact human health. Hence, to evaluate their persistence and understand the mechanisms that affect their fate, it is necessary to obtain realistic impact due to significant concentration of ENPs. The application of analytical techniques, such as ultraviolet (UV) spectroscopy, nuclear magnetic resonance (NMR), and inductively couple plasma spectroscopy-mass spectroscopy (ICP-MS), for the detection of ENPs in the natural environment is thus the heart of environmental research. The present review highlights the conjunction of sampling and separation tools with analytical techniques for detection and analysis of ENPs in the natural environment.

Nanotechnology is of great economic importance due to rapid growth in industrial and household applications and their continuous release into environmental matrices has increased the concerns regarding its potential impact on human and environment. To evaluate the potential toxicity of nanoparticles (NPs), the impact on humans and ecosystems needs to be understood from mechanistic insight by metabolomics. The analytical methods and omics technologies are particularly well-suited to evaluate these two dimensions in environment and both in vitro and in vivo systems, respectively. In this paper, the currently most effective methods for sampling and detection are presented together for future standardization of protocols providing profiles of NPs and associated metabolomics. All these approaches are designed without compromising the reliability and quality of the analytical results for their application in understanding the metabolomics and chemistry of NPs in the environmental matrices. Among sampling and separation, the most usable for worldwide comparisons of environmental matrixes are size-exclusion chromatography for size-exclusion, hydrodynamic chromatography coupled to inductively coupled plasma–mass spectrometry for size fractionation of engineered nanoparticles (ENPs) in environmental samples, gel electrophoresis for the separation of biological macromolecules, flow field flow fractionation (FIFFF) is widely used to separate NPs from environmental samples. The analytical tools for NPs associated metabolomics reveal immense potential for effects assessment such as liquid chromatography–mass spectrometry, gas chromatography–mass spectrometry, and nuclear magnetic resonance which are the most cost-effective and time-effective techniques. The omics technologies evaluate the toxicity profile of NPs by studying insight into nanotoxicity by application of both liquid chromatography/mass spectrometry and nuclear magnetic resonance–based metabolomics approaches. Also the proteomics leads to the analysis of biological system/biomarkers perturbs due to NPs interactions by using bioassay indicative of biomarkers related to pathways such as glucose metabolism, energy cycles, methylation and glutathione synthesis, and glucuronidation pathway and polyamine synthesis.

There are a number of techniques for measuring and characterization of nanoparticle (NP) size. One of the main problems in the field of NP analysis is in producing reliable and reproducible characterization data for nanomaterials (NMs). There is no one technique or method that is best suited for every situation, therefore the chosen methodologies improve results from a given sample matrix to produce the needed information in the shortest time and most cost-efficient way. A straightforward monitoring method may simply detect the presence of NMs; others may quantify the size distribution, surface area, or the number of the NPs. The interest in the development of wastewater treatment procedures is growing, therefore several clean-up technologies are being proposed in wastewater treatment that apply NMs as nanosorbents and photocatalysts. This review briefly introduces and compares the fundamental principles of routinely used NP size distribution measurements using both single particle (electron and scanning probe microscopy) and particle population methods, such as dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), and small angle X-ray scattering (SAXS) and outlines the latest applications of NMs, such as nano Ag, ${\mathrm{TiO}}_2$, ZnO, and iron oxide in wastewater treatment and gaps hindering their large-scale use. The outlook for potential applications as well as further challenges is discussed. Currently, DLS is not suitable for analysis of manufactured silver nanoparticles (AgNPs) in environmental samples, whereas the faster and easier to start with is NTA for ${\mathrm{TiO}}_2$ and ZnO nanomaterials in liquid matrices. Finally, an intercomparison of results between methods shows how different measurements are interpreted to give consistent results.

Engineered nanomaterials (ENMs) are manufactured for use in nanoproducts and during the lifecycle are released as waste nanoparticles (size $<100\mathrm{nm}$). The ENMs pose risks to workers and consumers, and when they become airborne, they cause broader effects on the environment and human health. Its increasing proportion in the atmosphere is a potential threat. In this, the past studies are reviewed to identify the types, effect-initiating properties, potential exposure pathways, and determine the effects on humans and atmospheric environment. The ENMs could be more hazardous than silica and asbestos because they are manufactured with specific properties and synthetically developed for wide applications. ENMs such as metals, metal oxides, and quantum dots are biopersistent, whereas fullerenes and single-walled carbon nanotubes cause adverse effects but have a shorter life span. The airborne ENMs may have modified properties and toxicological effects. Therefore, the knowledge of the inhalation toxicity of specific ENMs needs consideration in human exposure assessments.

The metal-aggregate industry is a dominating and unorganized industrial sector in India. The production of this aggregate is enormous to meet the ever-increasing demands of the construction industry. During crushing of stone aggregates in quarries, waste is generated, which is termed stone dust or quarry waste. The proper utilization or environment-friendly disposal of this stone dust is of concern. This paper presents the results of model walls with reinforced-stone dust as backfill, tested under strip loading with backfill compacted at varying relative densities of 17, 38, 59, and 73%. The model-wall facing was comprised of segmental blocks of concrete, and backfill was reinforced with bamboo-grid strips with a length-of-reinforcement-to-height-of-wall ratio ($L/H$) as 0.2, 0.3, 0.4, 0.5, and 0.6. The consequence of reduced-relative density of backfill (stone dust) on the facia displacement, settlement of backfill, and failure surcharge was studied. The results show that unreinforced-stone dust model walls collapse without much resistance when tested at a backfill relative density of 59% and lower. Stone dust is found to be a very effective material as a reinforced backfill and gives considerably good results with respect to facia displacement, failure surcharge pressure, and backfill settlement for a relative density at 59 and 73% with a minimum length of reinforcement $L/H$ as 0.5. The model walls constructed with a relative density at 38 and 17% display higher facia displacements and fail at low-surcharge values compared with the walls constructed with a relative density of backfill at 59 and 73%. This study helps in understanding the response of reinforced-stone dust walls corresponding to the range of relative densities used in experimental work and also helps to bring about an optimum effect without much wastage of material. With a view to further improving the performance of these model walls, expanded polystyrene geofoam blocks were placed behind each facia unit, and the wall behavior and performance was checked for geofoam densities of 0.12, 0.15, and $0.20\mathrm{kN}/{\mathrm{m}}^3$ with thickness variation as 5, 15, and 20 mm. Geofoam inclusion improves the overall behavior in terms of reduced-facia displacements, backfill settlements, and increased values of failure surcharges.

When disposed of after the end of their useful life, electronic communication devices such as cell phones pose significant environmental risks. Cell phones are one of the fastest growing contributors to the electronic waste (e-waste) stream. Increasing awareness about the environmental risk associated with the hazardous components of the electronic products and recent legislative pressure warrants the manufacturers to reduce or replace the hazardous materials with alternatives. The present study analyzes the economic consequences of reducing or replacing these hazardous materials and the possible response of the stakeholders. A strategic game theory model has been applied in this paper for three stakeholders considering the cost difference between hazardous substances-free (HSF) and hazardous substance (HS) cell phones. Results suggest that the HSF cell phones can be a preferred choice of the manufacturers and consumers if the cost of disposal of HS mobiles can be internalized, and a marginal incentive is given. The study further highlights the need for realizing the fact that passing on the incentives to the consumers to promote schemes for return back to producer or manufacturer at its end of life for effective reuse and recycling gives higher returns.

In nature, when contaminants come in contact with geomaterials (i.e., soil, minerals and rock mass), geomaterial-contaminant interaction occurs, which can be quantified, mathematically, by employing distribution or partitioning coefficient, $k_d$. This interaction is strongly influenced by the geomaterial and contaminant specific parameters. Among these parameters, the concentration and nature of the contaminant (in solution form) is one of the most important parameters that control this interaction critically. However, it is the authors’ hypothesis that another parameter, electrical conductivity of the geomaterial-contaminant system (GCS), which is dependent on type of the geomaterial (i.e., its chemical and mineralogical properties) and contaminant(s) could be used for a precise understanding of geomaterial-contaminant interaction. Hence, in order to investigate the effect of the concentration and electrical conductivity of the GCS on this interaction, geomaterials and contaminants of different types were used in this study for performing a series of batch tests and electrical conductivity measurements under controlled environmental conditions. Based on these investigations, guidelines for selecting appropriate concentration of the contaminant(s), $M_{\mathrm{crt}}$, to quantify geomaterial-contaminant interaction have been developed and recommended for the precise determination of $k_d$.

Biochar is one of a series of materials referred to as black carbon because it is produced by thermochemical transformation of the original biomass material under a variety of conditions. The objectives of this paper are to summarize the characteristics of biochar created from different feedstocks and identify the potential of biochar to maintain soil quality and sequester carbon. Biochar properties were analyzed in context to the biochar sources using indicators of their elemental compositions, pH, surface area, and cation exchange capacity. Application effects were also compared to evaluate the potential of biochar as a soil amendment and carbon capture agent on the basis of pot and field study results. Biochar performed well in terms of the improvement of soil pH and organic carbon, the stability of soil fertilizer generated from its large surface areas and cation exchange capacities. In general, the use of biochar proved to be an appropriate strategy for carbon neutralization resulting from carbon storage by itself and the decrease of total greenhouse gas emissions, including ${\mathrm{CO}}_2$, ${\mathrm{CH}}_4$, and ${\mathrm{N}}_2\mathrm{O}$, although the effects of biochar on each gas differed significantly. Overall, biochar exhibits great potential for expanded use in environmental fields; however, additional long term field studies that would assess biochar application rates are recommended.

Electrocoagulation is a versatile technique used for treating various types of industrial effluent. The material of the construction and shape of the electrodes are crucial in the electrocoagulation process. The effect of the electrode shape on the performance of the electrocoagulation has been studied by performing experiments for the removal of the dye from the synthetic dye solution using punched electrodes and the results have been evaluated in terms of color removal efficiency. The effect of the number of holes, the diameter of the hole, and the configuration of the holes (square, triangular, and random pitch of the holes) on the color removal efficiency was investigated. An increase in the color removal efficiency was obtained using the punched electrode compared with the plane electrode. The effect of the current source (direct and alternating current) on the performance of the electrocoagulation was studied and no significant effect of the current source on the performance of the electrocoagulation was noticed.