Showing papers by "Stephen J. Klaine published in 2015"

Responses of Hyalella azteca to acute and chronic microplastic exposures

Abstract: Limited information is available on the presence of microplastics in freshwater systems, and even less is known about the toxicological implications of the exposure of aquatic organisms to plastic particles. The present study was conducted to evaluate the effects of microplastic ingestion on the freshwater amphipod, Hyalella azteca. Hyalella azteca was exposed to fluorescent polyethylene microplastic particles and polypropylene microplastic fibers in individual 250-mL chambers to determine 10-d mortality. In acute bioassays, polypropylene microplastic fibers were significantly more toxic than polyethylene microplastic particles; 10-d lethal concentration 50% values for polyethylene microplastic particles and polypropylene microplastic fibers were 4.64 × 104 microplastics/mL and 71.43 microplastics/mL, respectively. A 42-d chronic bioassay using polyethylene microplastic particles was conducted to quantify effects on reproduction, growth, and egestion. Chronic exposure to polyethylene microplastic particles significantly decreased growth and reproduction at the low and intermediate exposure concentrations. During acute exposures to polyethylene microplastic particles, the egestion times did not significantly differ from the egestion of normal food materials in the control; egestion times for polypropylene microplastic fibers were significantly slower than the egestion of food materials in the control. Amphipods exposed to polypropylene microplastic fibers also had significantly less growth. The greater toxicity of microplastic fibers than microplastic particles corresponded with longer residence times for the fibers in the gut. The difference in residence time might have affected the ability to process food, resulting in an energetic effect reflected in sublethal endpoints. Environ Toxicol Chem 2015;34:2564–2572. © 2015 SETAC

Modeling the influence of physicochemical properties on gold nanoparticle uptake and elimination by Daphnia magna

Abstract: Monitoring the distribution and subsequent effects of nanoparticle contaminants in aquatic ecosystems will be pivotal to developing regulations that minimize their environmental footprint. The present study focused on the link between nanoparticle characteristics and Daphnia magna body burden using gold nanoparticles (AuNPs) with different size, shape, and surface charge configurations as model particles. Uptake followed first-order kinetics across the entire concentration range for all particles except the cationic rods, which demonstrated 2 distinct uptake patterns. Elimination followed the 2-compartment model for all particle configurations. Multiple regression analysis identified size and surface charge as controlling influences over AuNP uptake and elimination, whereas shape was regarded as inconsequential to both processes. Examination of the lumen-microvilli interface produced no evidence to indicate assimilation of the AuNPs used in the present study. Instead, these nanoparticles were restricted to the gut lumen and the carapace, where ingestion efficiency and adsorption were the primary determinants of total body burden. Models developed from the present data predict that D. magna will amass a higher body burden of larger cationic AuNPs at high concentration exposures and larger anionic AuNPs at low concentration exposures. A survey of the nanoparticle literature revealed that these trends were consistent with observations for certain nanomaterial exposures but could not be applied indiscriminately to all nanoparticle types and species. Environ Toxicol Chem 2015;34:860–872. © 2015 SETAC

Influence of carbon nanotubes on the bioavailability of fluoranthene

Abstract: Concurrent with the increase in the use of carbon nanotubes (CNTs) in society is the rise of their introduction into the environment. Carbon nanotubes cause adverse effects themselves, and they have the potential to adsorb contaminants such as polycyclic aromatic hydrocarbons (PAHs). Although CNTs have a high adsorption capacity for PAHs and these contaminants can co-occur in the environment, few studies have characterized the bioavailability of CNT-adsorbed PAHs to fish. The goal of the present study was to characterize the bioavailability of fluoranthene adsorbed to suspended multiwalled-carbon nanotubes (MWNTs) in freshwater containing natural organic matter (NOM). Adsorption isotherms indicated that NOM influenced the adsorption of fluoranthene to MWNTs, although in the absence of MWNTs it did not influence the bioavailability of fluoranthene to Pimephales promelas. Pimephales promelas were exposed for 16 h in synthetic moderately hard water containing fluoranthene in the presence of different concentrations of NOM, and fluoranthene adsorbed to MWNTs in the presence of NOM. Bioavailable fluoranthene was quantified in each exposure through bile analysis using fluorescence spectrophotometry. By comparing the concentration of fluoranthene metabolites in the bile with the concentration of fluoranthene added to MWNT and NOM solutions, the relative bioavailability of fluoranthene adsorbed to MWNTs was quantified. Results indicate that approximately 60% to 90% of the fluoranthene was adsorbed to the MWNTs and that adsorbed fluoranthene was not bioavailable to P. promelas. The results also suggest that fluoranthene is not desorbed from ingested MWNT, and the bioavailable fraction is only the freely dissolved fluoranthene in the aqueous phase. Environ Toxicol Chem 2015;34:658–666. © 2014 SETAC

Characterization of ecological risks from environmental releases of decamethylcyclopentasiloxane (D5)

Abstract: Decamethylcyclopentasiloxane (D5) is used in personal care products and industrial applications. The authors summarize the risks to the environment from D5 based on multiple lines of evidence and conclude that it presents negligible risk. Laboratory and field studies show that D5 is not toxic to aquatic organisms or benthic invertebrates up to its solubility limit in water or porewater or its sorptive capacity in sediment. Comparison of lipid-normalized internal concentrations with measured concentrations in benthos indicates that field-collected organisms do not achieve toxic levels of D5 in their tissues, suggesting negligible risk. Exposure to D5 resulted in a slight reduction of root biomass in barley at test concentrations 2 orders of magnitude greater than measured D5 levels in biosolids-amended soils and more than twice as high as the maximum calculated sorptive capacity of the soil. No effects were observed in soil invertebrates exposed to similar concentrations, indicating that D5 poses a de minimis risk to the terrestrial environment. High rates of metabolism and elimination of D5 compared with uptake rates from food results in biodilution in the food web rather than biomagnification, culminating in de minimis risk to higher trophic level organisms via the food chain. A fugacity approach substantiates all conclusions that were made on a concentration basis.