Lead Contamination in Ground Venison from Shotgun-Harvested White-Tailed Deer (Odocoileus virginianus) in Illinois.

Ground venison packets from shotgun- and archery-harvested White-tailed Deer in Illinois in 2013 and 2014 were analyzed for metal contamination. Radiographs indicated that 48% of 27 ground venison packets from 10 shotgun-harvested deer contained metal fragments, while none of the 15 packets from three archery-harvested deer contained fragments. ICP-MS analysis verified that all metal fragments from seven of the venison samples from shotgun-harvested deer were composed of lead, with average concentrations from 1.04 to 8.42 µg g-1, dry weight. A single serving of ground venison containing one of these metal fragments embedded in it would be predicted to have a lead concentration ranging from 6.4 to 51.8 µg g-1. Sixty percent of 20 commercial meat processing plants surveyed by phone in 2018 and 2019 indicated that they mixed venison from multiple deer when preparing ground venison products. However, our results do not show any cross-contamination in archery-harvested ground venison processed prior to the firearm hunting seasons.

Freshwater mussel shells (Unionidae) describe anthropogenic changes to trace element cycling within a North American river.

Bivalve shells provide an unparalleled opportunity for understanding the history of bioavailable trace elements in aquatic systems. The present study analyzed the elements Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, U, V and Zn in freshwater mussel shells collected from a large floodplain river. Shells were collected fresh, sampled from a historic archive, and retrieved from pre-Columbian archeological sites. The elements As, Co, Cu and Ni varied with time over the course of the 20th century. When compared to the pre-Columbian shells, 20th century shell concentrations for these elements were either consistently higher (Co, Cu and Ni) or lower (As). The 20th century shells also had consistently lower concentrations of Mn and Zn when compared to the pre-Columbian period, however diagenesis is the most likely cause of this difference in Mn. The elements Cd and Fe had little spatial or temporal variation in this data set. Several elements (Al, Cr, Hg, Pb, Se, U, and V) were below method detection limits in most shells. This study demonstrated that mussel shells can be used as archives of environmental history in river systems.

Chemosensory cues alter earthworm (Eisenia fetida) avoidance of lead-contaminated soil.

Earthworms were shown to significantly avoid soils spiked with Pb at concentrations lower than or comparable to concentrations that demonstrate significant effects for other endpoints. It was also shown that inclusion of a microorganism-produced volatile compound that attracts earthworms, ethyl valerate, decreased avoidance of spiked soils. These findings suggest that care should be taken when analyzing earthworm avoidance of soils in which microorganism communities are not controlled. Environ Toxicol Chem 2017;36:999-1004. © 2016 SETAC.

Zebra mussels (Dreissena polymorpha) as a biomonitor of trace elements along the southern shoreline of Lake Michigan.

The invasive zebra mussel (Dreissena polymorpha) has become an accepted biomonitor organism for trace elements, but it has yet to be studied along the Lake Michigan shoreline. Likewise, the relationships between tissue concentrations of elements, organism size, and sediment concentrations of elements have not been fully explained. The present study found that a variety of allometric variables such as length, dry tissue mass, shell mass, organism condition indices, and shell thickness index were useful in explaining intrasite variability in elemental concentrations. The flesh condition index (grams of tissue dry mass per gram of shell mass) explained variability at the most sites for most elements. Once allometric intrasite variability was taken into account, additional significant differences were found between sites, although the net effect was small. Significant positive relationships between sediment and tissue concentrations were found for Pb and Zn, with a significant negative relationship for Cd. It was also found that Cu and Zn concentrations in tissues increased significantly along the shoreline in the southeasterly direction, whereas Hg increased in a northwesterly direction. Opportunistic sampling found that zebra mussels accumulate significantly higher concentrations of nearly all elements analyzed compared to Asian clams (Corbicula fluminea) at the same site. The present study demonstrates the need to fully explain natural sources of variability before using biomonitors to explain spatial distributions of trace elements.

Improving data resolution and statistical rigor in the analysis of bivalve shells as environmental archives.

Bivalves secrete their shells in an annual fashion, resulting in discrete bands of growth within each shell. In doing so, they may incorporate trace elements in concentrations reflecting exposure. This may make it possible to use them as archives of environmental information, such as contamination events. In this study, we used laser ablation inductively coupled plasma-mass spectrometry to analyze trace elements (Cd, Cu, Mn, Pb and Zn) on a fly-scanning transect perpendicular to the growth annuli of the freshwater bivalve Elliptio hopetonensis collected from the Altamaha river system. Concentrations of Mn from multiple shells at each site were correlated and average Mn data series were formed. Periodicity of Mn data was determined and sampling errors removed using an autoregression model. The Mn data series at each site were shown to have regular fluctuations of high and low concentrations. Fluctuations were similar between the shells from the same site but different between shells from different sites, demonstrating that Mn deposition in the shells of E. hopetonensis follows a regular, seasonal pattern but that growth differs between sites with different environments. Cd, Cu, Pb and Zn could not be analyzed in a statistically robust manner. This is the first study to attempt to improve data resolution by using the fly-scanning approach and, additionally, the first to apply an autoregression model to Mn data from bivalve annuli. Further study is required to develop this approach for environmental monitoring.

Short-term molecular-level effects of silver nanoparticle exposure on the earthworm, Eisenia fetida.

Short-term changes in levels of expression of nine stress response genes and oxidative damage of proteins were examined in Eisenia fetida exposed to polyvinylpyrrolidone (PVP) coated Ag nanoparticles (Ag-NP) and AgNO(3) in natural soils. The responses varied significantly among days with the highest number of significant changes occurring on day three. Similarity in gene expression patterns between Ag-NPs and AgNO(3) and significant relationships of expression of CAT and HSP70 with Ag soil concentration suggest similarity in toxicity mechanisms of Ag ions and NPs. Significant increases in the levels of protein carbonyls on day three of the exposure to both ions and Ag-NPs indicate that both treatments induced oxidative stress. Our results suggest that Ag ions drive short term toxicity of Ag-NPs in E. fetida. However, given that <15% of Ag in the NPs was oxidized in these soils, dissolution of Ag-NPs is likely to occur after or during their uptake.

Trophic transfer of Au nanoparticles from soil along a simulated terrestrial food chain.

To determine if nanoparticles (NPs) could be transferred from soil media to invertebrates and then to secondary consumers, we examined the trophic transfer of Au NPs along a simulated terrestrial food chain. Earthworms (Eisenia fetida) were exposed to Au NPs in artificial soil media and fed to juvenile bullfrogs (Rana catesbeina). Earthworm Au concentrations were continuously monitored so that the cumulative dose to bullfrogs could be accurately estimated throughout the experiment. We exposed a second group of bullfrogs to equivalent doses of Au NPs by oral gavage to compare the bioavailability of NPs through direct exposure to trophic exposure. We observed accumulation of Au in liver, kidney, spleen, muscle, stomach, and intestine in both treatment groups. Tissue concentrations decreased on average of approximately 100-fold with each trophic-step. The total assimilated dose averaged only 0.09% of the administered dose for direct exposure (oral gavage), but 0.12% for the trophic exposure. The results suggest that manufactured NPs present in soil may be taken up into food chains and transferred to higher order consumers. They also suggest that Au NPs may be more bioavailable through trophic exposure than direct exposure and that trophic transfer may influence the biodistribution of particles once absorbed.

Evidence for bioavailability of Au nanoparticles from soil and biodistribution within earthworms (Eisenia fetida).

Because Au nanoparticles (NPs) are resistant to oxidative dissolution and are easily detected, they have been used as stable probes for the behavior of nanomaterials within biological systems. Previous studies provide somewhat limited evidence for bioavailability of Au NPs in food webs, because the spatial distribution within tissues and the speciation of Au was not determined. In this study, we provide multiple lines of evidence, including orthogonal microspectroscopic techniques, as well as evidence from biological responses, that Au NPs are bioavailable from soil to a model detritivore (Eisenia fetida). We also present limited evidence that Au NPs may cause adverse effects on earthworm reproduction. This is perhaps the first study to demonstrate that Au NPs can be taken up by detritivores from soil and distributed among tissues. We found that primary particle size (20 or 55 nm) did not consistently influence accumulated concentrations on a mass concentration basis; however, on a particle number basis the 20 nm particles were more bioavailable. Differences in bioavailability between the treatments may have been explained by aggregation behavior in pore water. The results suggest that nanoparticles present in soil from activities such as biosolids application have the potential to enter terrestrial food webs.

Comparison of metal concentrations in Corbicula fluminea and Elliptio hopetonensis in the Altamaha River system, Georgia, USA.

The present study evaluated the use of the invasive clam Corbicula fluminea as a surrogate for metal accumulation in native mussels. The tissue concentrations of As, Cd, Cu, Hg, Mn, Ni, Pb, and Zn were analyzed in Corbicula and a native Unionid mussel species (Elliptio hopetonensis) collected from 13 sites in the Altamaha River system (GA, USA). Corbicula accumulated greater concentrations of As, Cd, Cu, Hg, and Ni when compared to E. hopetonensis at the same sites. The reverse was true for the metals Mn and Zn, with E. hopetonensis accumulating greater concentrations than Corbicula. Concentrations of As, Cd, Cu, Hg, and Pb were found to be significantly (alpha = 0.05) positively correlated between the two species. Greater water alkalinity and hardness tended to negatively correlate with metal accumulation, while organism size tended to correlate positively with tissue concentrations. Tissue Cd, Cu, and Pb concentrations demonstrated a correlation between bivalve tissues and concentrations of those metals in fine sediments. These correlations were significant (alpha = 0.05) for Cd and Cu concentrations in Corbicula and Pb concentrations in E. hopetonensis. The present findings support the hypothesis that bioaccumulation of some metals by Corbicula can be used to approximate levels accumulated by co-occurring native mussel species.

The Asian clam Corbicula fluminea as a biomonitor of trace element contamination: accounting for different sources of variation using an hierarchical linear model.

In the present study, specimens of the invasive clam, Corbicula fluminea, were collected above and below possible sources of potentially toxic trace elements (As, Cd, Cr, Cu, Hg, Pb, and Zn) in the Altamaha River system (Georgia, U.S.A.). Bioaccumulation of these elements was quantified, along with environmental (water and sediment) concentrations. Hierarchical linear models were used to account for variability in tissue concentrations related to environmental (site water chemistry and sediment characteristics) and individual (growth metrics) variables while identifying the strongest relations between these variables and trace element accumulation. The present study found significantly elevated concentrations of Cd, Cu, and Hg downstream of the outfall of kaolin-processing facilities, Zn downstream of a tire cording facility, and Cr downstream of both a nuclear power plant and a paper pulp mill. Models of the present study indicated that variation in trace element accumulation was linked to distance upstream from the estuary, dissolved oxygen, percentage of silt and clay in the sediment, elemental concentrations in sediment, shell length, and bivalve condition index. By explicitly modeling environmental variability, the Hierarchical linear modeling procedure allowed the identification of sites showing increased accumulation of trace elements that may have been caused by human activity. Hierarchical linear modeling is a useful tool for accounting for environmental and individual sources of variation in bioaccumulation studies.

Enantioselective Chronic Toxicity of Fipronil to Ceriodaphnia dubia.

Fipronil is a phenylpyrazole pesticide that has greatly increased in popularity in recent years. As a chiral molecule, fipronil is released into the environment as a 1:1 mixture (called a racemate) of its two enantiomers. Previous toxicity work has indicated that the enantiomers of fipronil exhibit significantly different levels of acute toxicity to the nontarget organism Ceriodaphnia dubia. In this work we examine the chronic effects of the pure enantiomers and racemate on the survival, development, mobility, and reproduction of C. dubia adults and the survival and mobility of their offspring. Based on 8-day trials, the (+) enantiomer of fipronil showed a significantly greater reduction in the number of offspring (LOEC = 2 microg/L) than either the racemate (LOEC = 15 microg/L) or the (-) enantiomer (LOEC = 30 microg/L). The (+) enantiomer was also shown to be significantly more toxic to neonates born during the course of the experiment (LC50 24 = 18.1 microg/L, LC50 48 = 10.3 microg/L) than the racemate (LC50 24 = 33.3 microg/L, LC50 48 = 30.3 microg/L), but only after 48 h. Both the (+) enantiomer and the racemate were significantly more toxic to C. dubia than the (-) enantiomer (LC50 24 = 65.2 microg/L, LC50 48 = 50.1 microg/L) at both time points. Qualitative mobility data followed a similar trend, with the (+) enantiomer causing greater impairment in mobility at low concentrations. These data imply that the (-) enantiomer has less impact on the reproductive success of C. dubia than either the (+) enantiomer or the racemate. Enantiomerically pure or enriched formulations of (-) fipronil may reduce impacts to the nontarget organism C. dubia.

Toxicity of fipronil and its enantiomers to marine and freshwater non-targets.

Fipronil is a phenylpyrazole insecticide used in agricultural and domestic settings for controlling various insect pests in crops, lawns, and residential structures. Fipronil is chiral; however, it is released into the environment as a racemic mixture of two enantiomers. In this study, the acute toxicity of the (S,+) and (R,-) enantiomers and the racemic mixture of fipronil were assessed using Simulium vittatum IS-7 (black fly), Xenopus laevis (African clawed frog), Procambarus clarkii (crayfish), Palaemonetes pugio (grass shrimp), Mercenaria mercenaria (hardshell clam), and Dunaliella tertiolecta (phytoplankton). Results showed that S. vittatum IS-7 was the most sensitive freshwater species to the racemic mixture of fipronil (LC50 = 0.65 microg/L) while P. pugio was the most sensitive marine species (LC50 = 0.32 microg/L). Procambarus clarkii were significantly more sensitive to the (S,+) enantiomer while larval P. pugio were significantly more sensitive to the (R,-) enantiomer. Enantioselective toxicity was not observed in the other organisms tested. Increased mortality and minimal recovery was observed in all species tested for recovery from fipronil exposure. These results indicate that the most toxic isomer of fipronil is organism-specific and that enantioselective toxicity may be more common in crustaceans than in other aquatic organisms.