Contaminant exposure in terrestrial vertebrates

Here we review mechanisms and factors influencing contaminant exposure among terrestrial vertebrate wildlife. There exists a complex mixture of biotic and abiotic factors that dictate potential for contaminant exposure among terrestrial and semi-terrestrial vertebrates. Chemical fate and transport in the environment determine contaminant bioaccessibility. Species-specific natural history characteristics and behavioral traits then play significant roles in the likelihood that exposure pathways, from source to receptor, are complete. Detailed knowledge of natural history traits of receptors considered in conjunction with the knowledge of contaminant behavior and distribution on a site are critical when assessing and quantifying exposure. We review limitations in our understanding of elements of exposure and the unique aspects of exposure associated with terrestrial and semi-terrestrial taxa. We provide insight on taxa-specific traits that contribute, or limit exposure to, transport phenomenon that influence exposure throughout terrestrial systems, novel contaminants, bioavailability, exposure data analysis, and uncertainty associated with exposure in wildlife risk assessments. Lastly, we identify areas related to exposure among terrestrial and semi-terrestrial organisms that warrant additional research.     

Effect of two major N-nitroso hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) metabolites on earthworm reproductive success

Soil and topical tests were employed to investigate the effect of two N-nitroso metabolites of RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) on earthworm reproduction. The lowest observed effect concentration (LOEC) for cocoon production and hatching was 50mg/kg for both hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX) in soil. MNX and TNX also significantly affected cocoon hatching in soil (p<0.001) and in topical tests (p=0.001). The LOECs for cocoon hatching were 1 and 10mg/kg for MNX and TNX in soil, respectively, and 10mg/L in the topical test. Greater than 100mg/kg MNX and TNX completely inhibited cocoon hatching. In soil, the EC20 values for MNX were 8.7 and 8.8mg/kg for cocoon and juvenile production, respectively, compared to 9.2 and 9.1mg/kg for TNX, respectively. The EC20 values for the total number of cocoon hatchlings were 3.1 and 4.7mg/kg for MNX and TNX, respectively, in soil and 4.5 and 3.1mg/L in the topical test. Both MNX and TNX inhibited cocoon production and hatching, suggesting that they may have a negative affect on soil ecosystems at contaminated sites.     

Organochlorine contaminants in complete clutches of Morelet's crocodile (Crocodylus moreletii) eggs from Belize

Seven complete clutches of Morelet's crocodile (Crocodylus moreletii) eggs were collected in northern Belize and examined for organochlorine (OC) pesticide residues. The primary OC detected, p,p-DDE, was found in every egg analyzed (n=175). Other OCs detected included p,p-DDT, p,p-DDD, methoxychlor, aldrin, and endosulfan I. Concentrations of individual OCs ranged from 4 ppb (ng chemical/g egg wet weight) to greater than 500 ppb. A statistical evaluation of p,p-DDE levels in three complete clutches was used to derive the minimum number of eggs needed from a clutch to precisely determine the mean p,p-DDE concentration representative of that clutch. Sample sizes of 8 (80% confidence level) and 11 (90% confidence level) were determined to yield an accurate estimate of contaminant levels in a full clutch of eggs. The statistically recommended sample size of 11 eggs (at 90% confidence level) was successfully tested on the four additional clutches.     

European starling nestling response to chlorpyrifos exposure in a corn agroecosystem

European starling (Sturnus vulgaris) nestlings were used as a surrogate to study the effect of chlorpyrifos application to a corn agroecosystem on songbird reproduction. Chlorpyrifos was applied in a T‐band at 1.3 kg AI/ha, and residues were measured in soil, earthworms, ground‐dwelling insects, and diet items collected from the crop of starling nestlings. Chlorpyrifos levels in soil peaked at 34.2 μg/g, 4 days post‐application, and dissipated to trace levels by 64 days post‐application. Concentrations of chlorpyrifos in earthworms and ground‐dwelling insects reached 0.9 and 0.7 ug/g, respectively. Starling nestling diet items included invertebrates from eight orders with chlorpyrifos concentrations ranging from trace levels to 10.6 μg/g in earthworms. Nestling brain and plasma cholinesterase (ChE) activity and body mass measurements were taken at 3, 8, and 13 days post‐hatch (DPH). Adult starling fecundity was also measured. Body mass differences between treatment and reference site nestlings at 3 and 13 DPH were not significant at α = 0.05. However, 8 DPH nestlings from the Treatment Site had a transient reduction in weight (p = 0.03) when compared with 8 DPH reference nestlings. There were no significant differences in brain or plasma ChE activities of 3, 8, or 13 DPH nestlings. Further, multiple measures of fecundity (i.e., clutch size, hatching percentage, and fledging percentage) indicated that chlorpyrifos application did not affect starling nestling survival to fledging, as the values from the Treatment and Reference Site were nearly identical. This screening‐level study suggests that although one age group of starling nestlings from the Treatment Site weighed less than their Reference Site counterparts, a single T‐band application of chlorpyrifos did not impair starling nesting success.     

Monitoring perchlorate exposure and thyroid hormone status among raccoons inhabiting a perchlorate-contaminated site

Perchlorate is a water soluble anion that is readily accumulated in vegetation. It inhibits uptake of iodide into thyroid gland tissue, thereby reducing production of thyroid hormones. Potential raccoon food items including berries, fish, and vegetation collected at a contaminated site contained quantifiable concentrations of perchlorate as determined by ion chromatography. Therefore, we monitored resident raccoons for exposure to perchlorate by examining plasma perchlorate and thyroid hormone concentrations. Resulting analytical data failed to demonstrate perchlorate exposure among raccoons that likely consumed food items collected along perchlorate-contaminated water bodies. There were no correlations between triiodothyronine or thyroxine and thyroid stimulating hormone concentrations, but triiodothyronine concentrations in raccoon plasma were significantly higher in 2000 than in 2001 (p = 0.0081). These data suggest that natural attenuation and remedial efforts initiated in January of 2001 may have reduced perchlorate exposure among raccoons inhabiting this site from 2000 to 2001. Temporal, spatial, and analytical factors limited our ability to quantify exposure among raccoons, however, our data do not indicate that raccoons currently inhabiting this site are at risk for significant exposure to perchlorate and subsequent effects.     

Concentration and Composition of Atmospheric Aerosols from the 1995 SEAVS Experiment and a Review of the Closure between Chemical and Gravimetric Measurements

ABSTRACT

We summarize the results from the various measurements and the inter-sampler comparisons from Southeastern Aerosol and Visibility Study (SEAVS), a study with one of its objectives to test for closure among chemical, gravimetric and optical measurements of atmospheric aerosol particles. Sulfate and organics are the dominant components of the SEAVS fine particles (nominally, particles with aerodynamic diameter <2.5 u,m) but between 28 and 42% (range over various samplers) of the gravimetrically measured total fine particle concentration is unidentified by the chemical measurements. Estimates of water associated with inorganic components and measurement imprecision do not totally explain the observed difference between gravimetric and chemical measurements. We examine the theoretical and empirical basis for assumptions commonly made in the published literature to extrapolate total fine particle concentration on the basis of chemical measurements of ions, carbon and elements.     

Air quality measurements for the aerosol research and inhalation epidemiology study

Measurements of pollutant gases, airborne particulate matter mass and composition, and meteorology have been made at a core site near downtown Atlanta, GA, since August 1998 in support of the Aerosol Research and Inhalation Epidemiology Study (ARIES). This site is one of eight in the Southeastern Aerosol Research and Characterization network. The measurement objective is to provide a long-term, multivariate dataset suitable for investigating statistical associations of respiratory and cardiovascular disease with airborne particulate matter composition, meteorology, and copollutant gases through epidemiologic modeling. Measurements are expected to continue through 2010. Ancillary multiyear measurements at additional sites in the Atlanta metropolitan area and in short-term exposure assessments have been used to estimate the exposure/measurement error associated with using data from a central site to approximate human exposures for the entire area. To date, 13-, 25-, and 53-month air quality datasets have been used in epidemiologic analyses.     

In vivo effects of deltamethrin on some biochemical parameters of carp (Cyprinus carpio L.)

Thein vivo effects of deltamethrin (DM) on the blood sugar level, the acetylcholinesterase (AChE, EC 3.1.1.7) activities of the blood serum and various organs (heart, liver and intestine), the lactate dehydrogenase (LDH, EC 1.1.2.3), glutamic-oxaloacetic transaminase (GOT, EC 2.6.1.1), and glutamic-pyruvic transaminase (GPT, EC 2.6.1.2) activities of the blood serum, the adenosine triphosphatases (EC 3.6.1.3; Na⁺/K⁺-ATPase and Mg²⁺-ATPase) activities of the erythrocyte plasma membrane and the catalase (EC 1.11.1.6) activity of the liver were examined throughout 96 h in adult carp (Cyprinus carpio L.) Two sublethal concentrations, 1.0 and 1.5 µg/l of deltamethrin, were used. All fish survived the experiment except one, in an aquarium containing 1.5 ppb of DM, which died after 72 h.The AChE specific activity was significantly inhibited in the heart and intestine after 96 h at both concentrations compared to that in the control animals (P<0.05, Student'st-test), while there was no detectable difference between the two treatment. At the same time there was no detectable change in the liver. In the serum, the AChE activity almost remained unchanged; the only significant decrease could be measured after 96 h at 1.5 µg/l deltamethrin concentration. The blood glucose content exhibited interesting changes: after 24 h fish exposed at 1 µg/l DM seemed to be stressed, although this increase was not significant. When these fish became used to the new conditions (in practice this meant the presence of DM), the glucose level decreased, especially after 72 h. At the same time the control animals kept in similar circumstances showed a small insignificant decrease. Meanwhile fish in aquaria containing 1.5 µg/l DM reacted to the treatment with an increased blood glucose level after 48 h, and this did not change until the end of the treatment. The Na⁺/K⁺-ATPase activity decreased in a dose-dependant manner, while Mg²⁺-ATPase was less affected. A small increase in LDH level was observed, indicating damage of different muscle tissues. However, this phenomenon appeared only with the small dosage after 24 h (P<0.05). It has to be mentioned that the individual values varied to a large extent among of the eight fish.The GOT activities of the serum increased during the treatment. However, significant changes were only expressed after 72 and 96 h at 1 µg/l DM concentrations (P<0.01 andP<0.05), and after a similar long treatment at the high dosage (P<0.05, 72 and 96 h). The GPT did not change significantly in aquaria containing 1 µg/l DM. The only larger increase was measured after 96 h at 1.5 µg/l DM concentration (P<0.05). The catalase activity in the liver of treated carp remained practically at the same level compared to that in control fish.All these changes (concerning the primary effects of this compound) demonstrate the effect of DM on different fish enzymes, at low concentrations under laboratory conditions, which might be useful in practice for biomonitoring using fish.