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Toxics, Volume 5, Issue 3 (September 2017)

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Research

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Open AccessArticle Characterization of Aerosols of Titanium Dioxide Nanoparticles Following Three Generation Methods Using an Optimized Aerosolization System Designed for Experimental Inhalation Studies
Toxics 2017, 5(3), 14; doi:10.3390/toxics5030014
Received: 5 May 2017 / Revised: 26 May 2017 / Accepted: 10 June 2017 / Published: 1 July 2017
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Abstract
Nanoparticles (NPs) can be released in the air in work settings, but various factors influence the exposure of workers. Controlled inhalation experiments can thus be conducted in an attempt to reproduce real-life exposure conditions and assess inhalation toxicology. Methods exist to generate aerosols,
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Nanoparticles (NPs) can be released in the air in work settings, but various factors influence the exposure of workers. Controlled inhalation experiments can thus be conducted in an attempt to reproduce real-life exposure conditions and assess inhalation toxicology. Methods exist to generate aerosols, but it remains difficult to obtain nano-sized and stable aerosols suitable for inhalation experiments. The goal of this work was to characterize aerosols of titanium dioxide (TiO2) NPs, generated using a novel inhalation system equipped with three types of generators—a wet collision jet nebulizer, a dry dust jet and an electrospray aerosolizer—with the aim of producing stable aerosols with a nano-diameter average (<100 nm) and monodispersed distribution for future rodent exposures and toxicological studies. Results showed the ability of the three generation systems to provide good and stable dispersions of NPs, applicable for acute (continuous up to 8 h) and repeated (21-day) exposures. In all cases, the generated aerosols were composed mainly of small aggregates/agglomerates (average diameter <100 nm) with the electrospray producing the finest (average diameter of 70–75 mm) and least concentrated aerosols (between 0.150 and 2.5 mg/m3). The dust jet was able to produce concentrations varying from 1.5 to 150 mg/m3, and hence, the most highly concentrated aerosols. The nebulizer collision jet aerosolizer was the most versatile generator, producing both low (0.5 mg/m3) and relatively high concentrations (30 mg/m3). The three optimized generators appeared suited for possible toxicological studies of inhaled NPs. Full article
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Open AccessArticle Revelation of Different Nanoparticle-Uptake Behavior in Two Standard Cell Lines NIH/3T3 and A549 by Flow Cytometry and Time-Lapse Imaging
Toxics 2017, 5(3), 15; doi:10.3390/toxics5030015
Received: 31 May 2017 / Revised: 6 July 2017 / Accepted: 17 July 2017 / Published: 19 July 2017
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Abstract
The uptake of nanomaterials into different cell types is a central pharmacological issue for the determination of nanotoxicity as well as for the development of drug delivery strategies. Most responses of the cells depend on their intracellular interactions with nanoparticles (NPs). Uptake behavior
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The uptake of nanomaterials into different cell types is a central pharmacological issue for the determination of nanotoxicity as well as for the development of drug delivery strategies. Most responses of the cells depend on their intracellular interactions with nanoparticles (NPs). Uptake behavior can be precisely investigated in vitro, with sensitive high throughput methods such as flow cytometry. In this study, we investigated two different standard cell lines, human lung carcinoma (A549) and mouse fibroblast (NIH/3T3) cells, regarding their uptake behavior of titanium dioxide NPs. Cells were incubated with different concentrations of TiO2 NPs and samples were taken at certain time points to compare the uptake kinetics of both cell lines. Samples were analyzed with the help of flow cytometry by studying changes in the side and forward scattering signal. To additionally enable a detection via fluorescence, NPs were labeled with the fluorescent dye fluorescein isothiocyanate (FITC) and propidium iodide (PI). We found that NIH/3T3 cells take up the studied NPs more efficiently than A549 cells. These findings were supported by time-lapse microscopic imaging of the cells incubated with TiO2 NPs. Our results confirm that the uptake behavior of individual cell types has to be considered before interpreting any results of nanomaterial studies. Full article
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Open AccessFeature PaperArticle North Carolina Toxic Substance Incidents Program 2010–2015: Identifying Areas for Injury Prevention Efforts
Toxics 2017, 5(3), 16; doi:10.3390/toxics5030016
Received: 13 July 2017 / Revised: 3 August 2017 / Accepted: 3 August 2017 / Published: 6 August 2017
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Abstract
The National Toxic Substance Incidents Program (NTSIP) is a surveillance system designed to capture acute toxic substance releases, factors contributing to the release, and any associated injuries. North Carolina has participated since 2010, when NTSIP was established. This article will present a descriptive
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The National Toxic Substance Incidents Program (NTSIP) is a surveillance system designed to capture acute toxic substance releases, factors contributing to the release, and any associated injuries. North Carolina has participated since 2010, when NTSIP was established. This article will present a descriptive statistical summary from 2010 to 2015 focused on releases that resulted in injuries in order to identify areas for public health prevention efforts. Of the 1690 toxic releases in North Carolina, 155 incidents resulted in injuries and 500 people were injured. Carbon monoxide injured the greatest number of people. Of the incidents that resulted in injuries, 68 occurred at private vehicles or residences (44%), injuring 124 people (25%). Over half of events where at least one responder was injured occurred at private vehicles or residences. Events occurring at private residences did not have a significant relationship between evacuations and injuries, while for industry-related events, the odds of an evacuation being ordered were 8.18 times greater (OR = 8.18, 95% CI = 5.19, 12.89) when there were injuries associated with an event. Intervention efforts should focus on preventing responder injuries while responding to private residence releases and educating the general public on how to prevent injuries by self-evacuating areas where hazardous chemicals have been released. Full article
Open AccessArticle Do 16 Polycyclic Aromatic Hydrocarbons Represent PAH Air Toxicity?
Toxics 2017, 5(3), 17; doi:10.3390/toxics5030017
Received: 30 June 2017 / Revised: 9 August 2017 / Accepted: 10 August 2017 / Published: 15 August 2017
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Abstract
Estimation of carcinogenic potency based on analysis of 16 polycyclic aromatic hydrocarbons (PAHs) ranked by U.S. Environmental Protection Agency (EPA) is the most popular approach within scientific and environmental air quality management communities. The majority of PAH monitoring projects have been focused on
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Estimation of carcinogenic potency based on analysis of 16 polycyclic aromatic hydrocarbons (PAHs) ranked by U.S. Environmental Protection Agency (EPA) is the most popular approach within scientific and environmental air quality management communities. The majority of PAH monitoring projects have been focused on particle-bound PAHs, ignoring the contribution of gas-phase PAHs to the toxicity of PAH mixtures in air samples. In this study, we analyzed the results of 13 projects in which 88 PAHs in both gas and particle phases were collected from different sources (biomass burning, mining operation, and vehicle emissions), as well as in urban air. The aim was to investigate whether 16 particle-bound U.S. EPA priority PAHs adequately represented health risks of inhalation exposure to atmospheric PAH mixtures. PAH concentrations were converted to benzo(a)pyrene-equivalent (BaPeq) toxicity using the toxic equivalency factor (TEF) approach. TEFs of PAH compounds for which such data is not available were estimated using TEFs of close isomers. Total BaPeq toxicities (∑88BaPeq) of gas- and particle-phase PAHs were compared with BaPeq toxicities calculated for the 16 particle-phase EPA PAH (∑16EPABaPeq). The results showed that 16 EPA particle-bound PAHs underrepresented the carcinogenic potency on average by 85.6% relative to the total (gas and particle) BaPeq toxicity of 88 PAHs. Gas-phase PAHs, like methylnaphthalenes, may contribute up to 30% of ∑88BaPeq. Accounting for other individual non-EPA PAHs (i.e., benzo(e)pyrene) and gas-phase PAHs (i.e., naphthalene, 1- and 2-methylnaphthalene) will make the risk assessment of PAH-containing air samples significantly more accurate. Full article
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Open AccessArticle Differential Effects of Low-Molecular-Weight Organic Acids on the Mobilization of Soil-Borne Arsenic and Trace Metals
Toxics 2017, 5(3), 18; doi:10.3390/toxics5030018
Received: 2 August 2017 / Revised: 9 August 2017 / Accepted: 17 August 2017 / Published: 21 August 2017
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Abstract
A batch experiment was conducted to examine the effects of six low-molecular-weight organic acids on the mobilization of arsenic and trace metals from a range of contaminated soils. The results showed that the organic acids behaved differently when reacting with soil-borne As and
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A batch experiment was conducted to examine the effects of six low-molecular-weight organic acids on the mobilization of arsenic and trace metals from a range of contaminated soils. The results showed that the organic acids behaved differently when reacting with soil-borne As and trace metals. Oxalic acid and acetic acid had the strongest and weakest capacity to mobilize the investigated elements, respectively. The solubilisation of iron oxides by the organic acids appears to play a critical role in mobilizing other trace metals and As. Apart from acidification and complexation, reductive dissolution played a dominant role in the dissolution of iron oxides in the presence of oxalic acid, while acidification tended to be more important for dissolving iron oxides in the presence of other organic acids. The unique capacity of oxalic acid to solubilize iron oxides tended to affect the mobilization of other elements in different ways. For Cu, Mn, and Zn, acidification-driven mobilization was likely to be dominant while complexation might play a major role in Pb mobilization. The formation of soluble Fe and Pb oxalate complexes could effectively prevent arsenate or arsenite from combining with these metals to form solid phases of Fe or Pb arsenate or arsenite. Full article
(This article belongs to the Special Issue Fate and Transport of Contaminants in Soil and Groundwater Systems)
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Open AccessArticle Farmers’ Training on Pesticide Use Is Associated with Elevated Safety Behavior
Toxics 2017, 5(3), 19; doi:10.3390/toxics5030019
Received: 26 June 2017 / Revised: 14 August 2017 / Accepted: 20 August 2017 / Published: 22 August 2017
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Abstract
Occupational exposure to pesticides in agricultural applications may cause acute and long-term health effects to farmers, and thus research on factors that reduce exposure is useful. However, studies on the relevance and effectiveness of training are limited. The association of previous training in
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Occupational exposure to pesticides in agricultural applications may cause acute and long-term health effects to farmers, and thus research on factors that reduce exposure is useful. However, studies on the relevance and effectiveness of training are limited. The association of previous training in the form of intensive seminars relating to pesticide use (e.g., use of spraying equipment, application parameters, use of personal protective equipment, risks to human health and the environment) with farmers’ knowledge and behavior in pesticide use was studied via the self-reporting method in a purposive sample of 82 trained and non-trained farmers. Most trained farmers showed higher levels of knowledge of pesticide use, higher levels of beliefs in pesticide hazard control, and higher levels of safety behavior than non-trained farmers. Knowledge of pesticide use and beliefs regarding pesticide hazard control were significantly correlated with safety behavior in both groups of farmers. Concerning farmers’ beliefs regarding pesticide hazard control, trained farmers were more likely to think that safety precautions work very well and less likely to feel they had little control over avoiding pesticide hazards. Overall, previous training was associated with increased levels of farmers’ knowledge of pesticides and beliefs about pesticide hazard control, was accompanied by elevated safety behavior in farmers, and thus was connected with lower occupational exposure to pesticides. Interventions that facilitate knowledge and compliance with safety behaviors should become a priority for decreasing exposure to pesticides among farmers. Full article
(This article belongs to the collection Risk Assessment of Pesticide Exposure)
Open AccessArticle Metal Levels in Blood of Three Species of Shorebirds during Stopover on Delaware Bay Reflect Levels in Their Food, Horseshoe Crab Eggs
Toxics 2017, 5(3), 20; doi:10.3390/toxics5030020
Received: 31 July 2017 / Revised: 14 August 2017 / Accepted: 18 August 2017 / Published: 28 August 2017
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Abstract
Understanding the relationship between metal level in predators and their prey is an important issue, and is usually difficult to determine because animals eat a variety of organisms. However, shorebirds that stop over during spring migration along Delaware Bay (New Jersey) stay for
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Understanding the relationship between metal level in predators and their prey is an important issue, and is usually difficult to determine because animals eat a variety of organisms. However, shorebirds that stop over during spring migration along Delaware Bay (New Jersey) stay for only 2–3 weeks, and eat mainly horseshoe crab (Limulus polyphemus) eggs. In this paper, we examine the relationship between metal levels in horseshoe crab eggs, and blood and feather levels of metals in red knot (Calidris canutus rufa; n = 30), sanderling (Calidris alba; n = 20) and semipalmated sandpiper (Calidris pusilla; n = 38) from Delaware Bay. There is a rich literature on metal levels in feathers. For all three species, the levels of arsenic, cadmium, chromium, lead and mercury in blood were highly correlated with the levels of metals in the eggs of horseshoe crab (17 pooled samples). This indicates that the levels in the blood of these shorebirds quickly reflect levels in their prey (horseshoe crab eggs), while metals in the feathers were not correlated with the levels in eggs. Semipalmated sandpipers had the lowest levels of arsenic in blood and the highest levels of arsenic in feathers, compared to the other species. At Delaware Bay, semipalmated sandpipers have a diet higher in marsh invertebrates than the other species, which may account for the differences. The levels of cadmium and chromium in blood were significantly higher in knots than other species; knots only ate horseshoe crab eggs. For all of the metals except arsenic, the ratio of levels in blood/feathers was similar among species. For arsenic, the ratio of levels in blood/feathers were significantly lower in semipalmated sandpipers than in the other species, by an order of magnitude. Full article
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Open AccessArticle A Retrospective Analysis of Agricultural Herbicides in Surface Water Reveals Risk Plausibility for Declines in Submerged Aquatic Vegetation
Toxics 2017, 5(3), 21; doi:10.3390/toxics5030021
Received: 10 August 2017 / Revised: 29 August 2017 / Accepted: 30 August 2017 / Published: 6 September 2017
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Abstract
The Albemarle-Pamlico Estuarine System (APES) is the second largest estuarine system within the mainland of the United States and is estimated to have lost about half of its submerged aquatic vegetation (SAV) over the past several decades. The issue of herbicide runoff and
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The Albemarle-Pamlico Estuarine System (APES) is the second largest estuarine system within the mainland of the United States and is estimated to have lost about half of its submerged aquatic vegetation (SAV) over the past several decades. The issue of herbicide runoff and subsequent toxic effects to SAV is important because of the extensive agricultural production that occurs in the APES region. The aim of this study was to conduct a retrospective analysis of herbicide influx to waters of the APES region during the time period of documented SAV declines and to compare the measured concentrations to SAV toxicity thresholds and changes in agricultural land use. Surface water grab samples were collected at 26 sites in the APES region during May through July 2000. The most consistently measured herbicides were alachlor, atrazine, and metolachlor with geometric mean concentrations ranging from 29 to 2463 ng/L for alachlor, 14 to 7171 ng/L for atrazine, and 17 to 5866 ng/L for metolachlor. Concentrations of alachlor, atrazine, and metolachlor measured in water samples from the APES region in 2000 exceeded several of the established benchmarks, standards, or guidelines for protection of aquatic plants. Although this evaluation was of point-in-time herbicide samples (year 2000) and not analyzed for all possible herbicides used at the time, they were taken during the period of SAV declines, reveal the plausibility of exposure risk to SAV, and suggest that herbicide runoff should be studied along with other variables that influence SAV growth and distribution in future studies. Full article
(This article belongs to the collection Risk Assessment of Pesticide Exposure)
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Review

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Open AccessReview Occupational Exposure to Bisphenol A (BPA): A Reality That Still Needs to Be Unveiled
Toxics 2017, 5(3), 22; doi:10.3390/toxics5030022
Received: 18 July 2017 / Revised: 25 August 2017 / Accepted: 11 September 2017 / Published: 13 September 2017
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Abstract
Bisphenol A (BPA), 2,2-bis(4-hydroxyphenyl) propane, is one of the most utilized industrial chemicals worldwide, with the ability to interfere with/or mimic estrogenic hormones with associated biological responses. Environmental human exposure to this endocrine disruptor, mostly through oral intake, is considered a generalized phenomenon,
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Bisphenol A (BPA), 2,2-bis(4-hydroxyphenyl) propane, is one of the most utilized industrial chemicals worldwide, with the ability to interfere with/or mimic estrogenic hormones with associated biological responses. Environmental human exposure to this endocrine disruptor, mostly through oral intake, is considered a generalized phenomenon, particularly in developed countries. However, in the context of occupational exposure, non-dietary exposure sources (e.g., air and contact) cannot be underestimated. Here, we performed a review of the literature on BPA occupational exposure and associated health effects. Relevantly, the authors only identified 19 studies from 2009 to 2017 that demonstrate that occupationally exposed individuals have significantly higher detected BPA levels than environmentally exposed populations and that the detection rate of serum BPA increases in relation to the time of exposure. However, only 12 studies performed in China have correlated potential health effects with detected BPA levels, and shown that BPA-exposed male workers are at greater risk of male sexual dysfunction across all domains of sexual function; also, endocrine disruption, alterations to epigenetic marks (DNA methylation) and epidemiological evidence have shown significant effects on the offspring of parents exposed to BPA during pregnancy. This overview raises awareness of the dramatic and consistent increase in the production and exposure of BPA and creates urgency to assess the actual exposure of workers to this xenoestrogen and to evaluate potential associated adverse health effects. Full article
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