Brief Summary of Minutes of Annual Meeting

Objective 1: Identify, develop, and/or validate trace residue analytical methods, immunological procedures, and biomarkers Concentrated animal feeding operation (CAFO) waste is a cost effective fertilizer. However, land-applied wastes from concentrated animal feeding operations can have negative impacts on fish populations and communities. To examine these impacts, Purdue University scientists evaluated a network of subsurface tile-drains facilitates transport of animal hormones and nutrients from land-applied CAFO waste to adjacent waterways in the Midwest. The objective of this work was to better understand impacts of land-applied CAFO waste on fish populations and communities. Water hormone concentrations were characterized from study sites. Fish assemblage structure, reproductive condition, and potential endocrine disruption were assessed in selected fish species. CAFO water samples showed hormone concentrations < 1 ng/L, peaks in 17²-E2 (32.95 ng/L) and 17±-TB (34.28 ng/L) equivalent concentrations were registered at times when resident fishes spawn, hatch, and develop. However, CAFO sites had lower fish species richness, and fishes exhibited lower reproductive condition compared to individuals from reference habitats. Fathead minnows (Pimephales promelas) exposed to CAFO ditchwater during early developmental stages were observed to exhibit significantly skewed sex ratios towards males. Maximum observed hormone loads were well above the lowest observable effect concentrations for these hormones. Decrease species richness, altered gonadal development, increased growth rates, and skewed sex ratios towards males could be a result of hormone exposure. These Midwest research findings can have broad ecosystem implications in other US regions where CAFO land-applied wastes are in proximity to critical aquatic habitat. Further research will therefore be needed that investigates potential links between hormone loads and aquatic biotic assemblages. Endosulfan has been identified as a Persistent Organic Pollutants (POP) by the United Nations (UN) and is being phased out in the United States due to risks to agricultural workers and to wildlife. Although little is known about regional and local transport, it readily undergoes long-range atmospheric transport. USDA-ARS Beltsville scientists conducted extensive field evaluations to characterize the atmospheric fate of endosulfan in South Florida, a region where this compound is still heavily used. Air samples were collected in the agricultural area of Homestead (HAA) and at Everglades (EVR) and Biscayne National Parks (BNP). The ± isomer of endosulfan was detected in nearly all samples (95 to 98%) at HAA and EVR and in 61% of the samples at BNP. The overall mean gas phase air concentration of ±-endosulfan at HAA (17 ± 19 ng m-3), which is located within the agricultural production area, was an order of magnitude greater than the mean concentration at EVR (2.3 ± 3.6 ng m-3) and two orders of magnitude larger than the mean concentration at BNP (0.52 ± 0.69 ng m-3). The differences between median concentrations at each of these sites were highly significant (p < 0.0001) reflecting the differences in proximity to pesticide application activities. ²-endosulfan was also frequently detected in the gas phase at HAA (94 to 95%), less at EVR (74% and 93%, respectively), and infrequently at BNP (d 32%). Mean air concentrations of ²-endosulfan were approximately 3 to 5 times lower than ±-endosulfan at each station. The consistent detections observed from this area-wide investigation indicate that heavy agricultural use of endosulfan can lead to locally-high atmospheric concentrations. Model predictions and measurements also suggest that residues were transported into ecologically sensitive areas of Everglades and Biscayne National Parks, although the magnitude of deposition is unknown. Utilizing the unique properties of the two endosulfan isomers, the contributions of drift versus volatilization to air concentrations observed in the field was characterized. A combination of both drift and volatilization processes influenced the atmospheric concentrations of endosulfan at Homestead and at Everglade NP, while volatilization was the primary emission process affecting endosulfan levels at Biscayne NP. The observed long range transport of endosulfan from areas of high agricultural use to sensitive land areas in Florida corroborates with recent UN provisions for phasing out this substance for US agriculture. National and international monitoring studies have reported detection of contaminants of emerging concern (CEC, e.g. pharmaceuticals, antibiotics, hormones, additives to personal care products, wastewater contaminants, etc.) in surface waters and ground waters. A number of these contaminants can cause adverse ecological and human health impacts, and occur as complex mixtures in the environment. One of the greatest barriers to addressing the problem of CECs is a lack of understanding of where these compounds come from and which sources dominate in different locations and at different times. USDA-ARS Minnesota scientists are conducting land assessments that employed water and sediment analytical evaluations from four sub-watersheds in southeastern Minnesota, two dominated by agricultural land use and two dominated by urban land use. The output from these evaluations addressing contaminant concentrations and their temporal occurrences in each sub-watershed will reflect the surrounding land use and serve as markers for that land use. These markers can be used to determine the comparative load of CECs to water, which can in turn aid in developing prudent strategies to reduce their occurrence. Confirmation of contaminant signatures associated with land use will provide a tool that can be implemented in watersheds not only in Minnesota but other regions throughout the US to identify and track pollution sources. Once contaminant sources are identified, management and mitigation strategies can be implemented to reduce their occurrence; protecting aquatic habitats and potentially, human health. Objective 2: Characterize abiotic and biotic reaction mechanisms, transformation rates, and fate in agricultural and natural ecosystems Pollution of water and soil in the environment by toxic organic pollutants such as pesticides has become a widespread concern for water quality and as a source of serious hazards for humans and other living species. Advanced oxidation processes (AOPs) have been developed by New York Cornell experimental station scientists as effective treatments to remediate environmental pollutants in water, and Fenton treatment has been extensively applied to degrade environmental pollutants. Recent efforts focused on heterogeneous Fenton-like reactions on nano-magnetite (Fe3O4) for the degradation of p-Nitrophenol (p-NP). A four factor central composite design (CCD) coupled with response surface methodology (RSM) was applied to evaluate and optimize important reactivity variables. A significant quadratic model was derived using analysis of variance (ANOVA), or variable optimization. Optimum conditions were determined to be 1.5 g L-1 Fe3O4, 620 mM H2O2, pH 7.0 and 25-45 mg L-1 p-NP. More than 90% of p-NP was experimentally degraded after 10 h of reaction time under the optimum conditions, which agreed well with the model predictions. The results demonstrated that the degradation of p-NP was due to the attack of hydroxyl radicals (OH) generated by the surface-catalyzed decomposition of hydrogen peroxide on the nano-Fe3O4, i.e. heterogeneous Fenton-like reactions. Possible mechanisms of p-NP degradation in this system are being advanced, based on intermediates identified by LC-MS and GC-MS and included benzoquinone, hydroquinone, 1,2,4-trihydroxybenzene and p-nitrocatechol. Fenton reactions using nano-magnetite as the iron source can be a viable Fenton remediation method. When the reactions take place on the surface of the mineral, it can often be done at ambient pH. The kinetics of these processes conducted under neutral non-acidic conditions on nano-scale substrates must be understood to provide the basis for broader US-based field applications. A continuous water monitoring tactic was used for the organophosphate insecticide chlorpyrifos, widely used in Oregon watersheds that are designated critical habitat for Endangered Species Act listed salmonid species. Oregon State experimental station scientists deployed a lipid-free tubing passive sampling device (LFT) at five locations in the Pudding River basin Willamette Valley, OR. This device can continuously assay chlorpyrifos in a watershed predominately agricultural and classified as habitat for salmonid species. LFT were deployed continuously in off-channel habitats, including backwaters, channel edge sloughs, and off-channel pools, at 3-4 week intervals from June 2010 to October 2011. Time-weighted average concentrations of freely dissolved pesticides were quantified by dual column gas chromatography with electron capture detection and confirmed with mass selective detection. Chlorpyrifos was detected above the limit of quantitation (0.01 ng/L) in over 95% of samples. The high frequency of detection of chlorpyrifos can be attributed to the potential widespread use on agricultural commodities produced in the Pudding River basin. Peaks in concentrations occurred during June sampling events as well as the beginning and end of winter. Peaks in the chlorpyrifos concentration occurred at certain creek sites in the winter and late spring. Peaking concentrations in shallow stream and off-channel habitats during the high flow periods of fall and winter may be of interest due to juvenile salmonids utilizing these habitats as shelter from the high flows of the main channel. However in the Pudding River basin, only the levels measured at one creek monitoring site begin to approach the salmonid prey LC50, the most sensitive toxicological endpoint utilized by NMFS in the BiOp. This monitoring approach may be useful in refining conservative estimates of chlorpyrifos surface water loading derived from screening models and inform the selection of agricultural best management practices (BMPs) in the Pudding Subbasin, Oregon. The adoption of LFT approaches can potentially have broader application in Pacific Northwest states for risk assessment and formulating BMPs in ESA critical habitat regions. Gaseous methyl isothiocyanate (MITC), the principal breakdown product of the soil fumigant metam sodium (sodium methyl-dithiocarbamate), is an inhalation exposure concern to the public and farmworkers, particularly in residential communities near large production acreages. Inhalation exposure may not be limited to MITC but may also include methyl isocyanate (MIC), a toxic tropospheric oxidative transformation product of MITC. Under controlled laboratory conditions, the gas phase reaction of hydroxyl (OH) radicals with MITC was examined by Nevada experimental station scientists working collaboratively with Washington State experimental station scientists using static relative rate techniques in 10 L Tedlar air sampling bags over a 1 hr period. Gas phase MITC, MIC and OH reference compounds (xylene and toluene) were quantified by solid phase microextraction-GC/MS. In this work a MITC OH rate constant of 13.7 x 10-12 cm3 molecule-1 s-1 was estimated. The MITC atmospheric lifetime would be 1.8 hours under tropospheric OH radical concentrations of 8.0 x 105 molecules cm-3 over a period of 24 hrs. MIC was observed to be the primary transformation product in the gas phase and the rate constant for OH oxidation was determined to be 3.79 x 10-12 cm3 molecule-1 s-1, with an atmospheric half life of 6.4 hours. This work has provided an important component for conducting a risk assessment that can be incorporated into estimates of human exposure to MITC and MIC under a variety of application and atmospheric conditions. Moreover, efficiency of conversion of MITC to MIC conversion (to be determined) will take on regulatory importance when characterizing human inhalation exposure risks in high intensity fumigation regions that exist at the rural-urban interface. Objective 3: Determine adverse impacts from agrochemical exposure to cells, organisms, and ecosystems West Nile virus (WNV) is now considered endemic to North America. Since the arrival of WNV, more areas of the country have been experiencing large-scale insecticide applications for mosquito-borne pathogens like WNV. This has renewed public attention on mosquito management. The concerns have revolved around two major management areas: the effectiveness of outdoor space sprays to manage adult mosquitoes, termed adulticiding, and the environmental risks posed by adulticiding. Efforts by Montana State University scientists have investigated toxicity, exposure, and risk to management tactics for insect disease vectors. Here, actual environmental concentrations of insecticides and to relate those concentrations to higher-tier human exposure and risk assessments were modeled using probabilistic approaches on 2009-2011 ground-based ultra-low-volume (ULV) field data from Montana, California, and Louisiana. Using the predicted insecticide concentrations from the environmental model, a probabilistic risk assessment of acute human exposure to the pyrethroid insecticide permethrin was conducted. The coefficients of the selected model showed that the density of the formulation and diameter of the droplets are the most important determinants of the movement and subsequent deposition of ULV insecticides. Risks to toddlers and infants were highest while risks to adult males were lowest, but all risks were far below USEPA levels of concern. The sensitivity analysis demonstrated that > 95% of the variance to the exposure was from deposition on surfaces. Because a large data set to model concentrations deposited on surfaces, variance in exposure was due to the inherent variability in deposition concentrations after ULV applications and, therefore, would not warrant further refinement to improve risk assessments. The body of this modeling work suggest regulatory agencies consider probabilistic approaches that can both improve and standardize their risk assessments for registration and re-registration of relevant insecticides. The impact of non-lethal agrochemical/environmental exposures on non-target avian species is difficult to assess, particularly in terms of developing Natural Resource Damage Assessments (NRDA). University of Nevada scientists have developed the homing pigeon model to study non-lethal exposures in avian species. Mercury is one of the most common metals found in contaminated ecosystems. It occurs naturally, but high levels found in contaminated areas generally derive from human use practices. Among the most vulnerable species to exposure are birds that live, nest, or feed in or near these contaminated ecosystems. Because of the known neurological effects of mercury on birds, it is hypothesized that effects upon migratory ability would be evident after exposure to low levels of this metal, and effects may be exacerbated in young birds. In this study, breeding pigeons were exposed to ~1.0 mg/kg/day methylmercury via the drinking water, and first round offspring were trained to home after fledging, while also continually exposed to methylmercury. The young pigeons were released individually for three flights, and flight times were assessed and compared to control young pigeon flight times from 3.5, 9, 21, 53, 65, and 98 air miles as well as two individual flights at ~50 air miles from multiple directions. Results indicate that methylmercury exposed birds exhibit slower flight times than controls during the initial flight, and generally improve on successive flights at each distance and direction. This may suggest non-lethal methylmercury exposure results in pigeon orientation impairment and alludes to migration disruption in avian migratory species. The United States uses pyridostigmine bromide (PB) as a prophylactic to the toxic effects of soman, a chemical warfare agent, but there has been no detailed study of the protective effects of carbamates on exposure to pesticides. Previous research has showed that PB significantly protected human muscle acetylcholinesterase (AChE) in vitro. Research presented by University of California Davis scientists demonstrates that inhibition of bovine red blood cell (RBC) AChE is also protected by carbamates from the organophosphate (OP) pesticides chlorpyrifos-oxon and diazinon-oxon, but not from malaoxon. Further study is needed of the extent of the protective effect of PB and other carbamates. The findings suggest that PB pretreatment may protect growers and farmworkers in the workplace, and the lay public in the event of terrorist attacks. Objective 4: Develop technologies that mitigate adverse human and environmental impacts University of Florida Gainsville scientists completed a subsurface diffusion and surface emission field investigation of cis- and trans-1,3-dichloropropene (1,3-D) and chloropicrin (CP) after application of carbonated (product dispersed with CO2) and uncarbonated Telone C35 (63.4% 1,3-D and 34.7% chloropicrin) under VIF (virtually impermeable film) or TIF (totally impermeable film). The carbonation process allows for greater product dispersion. Conclusions to be drawn from spring 2011 Florida trials indicate: 1) The carbonation of Telone C35 resulted in the fumigant reaching a greater depth than the C35 applied by nitrogen. This should reduce the nematode re-infestation of the bed from below; 2) The carbonation of Telone C35 caused greater lateral movement than observed by Telone C35 dispersed by nitrogen. Additionally, the dissipation of carbonated Telone C35 was faster than the Telone C35 applied by nitrogen which implies that the plant-back time may be shortened; 3) Weeds puncturing the plastic film on the beds were greatly reduced by the TIF compared to VIF; 4) Root galling index implied that there was very little difference in nematode control between carbonated and non-carbonated Telone C35 when applied at the same rate. However, it should be noted that the plots treated with reduced one-third rate of Telone C35 by nitrogen showed better nematode control than those plots treated at the full rate of Telone C35 by nitrogen. It was later confirmed that field was infested with Pasteuria penetrans, an obligate parasite of nematodes. Field variability of parasite infestation was implied by the large standard error associated with the average value for replicants, and 5) Marketable crop yield for plots treated with carbonated Telone C35 were slightly greater than the Methyl Bromide plots or the plots treated by Telone C35 dispersed by nitrogen, but not statistically significant. This combined technology can have potential in other US row crop regions seeking alternatives to methyl bromide soil fumigation. Mustard ground cover crop incorporation can serve as a useful biofumigation addition for suppression of economically important soilborne pathogens while reducing the need for chemical fumigation. The rapid increasing use of mustard biofumigation in rotational crop practices has also drawn greater public health attention. Concerns have been expressed that naturally occurring isothiocyanates (ITCs) generated during field incorporation may present an inhalation hazard to field operators and bystanders. Field studies conducted by Washington State University experimental station scientists provides preliminary field air concentration data for three ITCs (allyl, benzyl, and phenethyl isothiocyanate) during and shortly after field incorporation of a mixed Indian/yellow mustard cover crop. The ITC air concentration data was collected within a 41 hectare crop circle and at four perimeter sampling locations following cultivation of two species of intermixed mustard, Brassica juncea (Indian mustard) and Sinapis alba (yellow mustard). Air samples were collected by activated charcoal before, during, and 4-days after mustard soil incorporation. Field air monitoring and analytical methods were developed specifically to target allyl, benzyl, and phenethyl isothiocyanate. The highest observed ITC concentrations occurred during tractor flail-chopping and disking field operations with maximum single receptor air concentrations of 47 ppb, 1 ppb, and 0.1 ppb, respectively, for the allyl, benzyl, and phenethyl isothiocyanates. ITC measured air emissions attenuated shortly after soil incorporation activities ceased. Although risks to these targeted ITCs are not well developed, the concentrations found in air do not appear to pose an acute human inhalation exposure concern. For the allyl isothiocyanate, based on extrapolations from animal dermal lethal dose 50% data, the maximum observed air concentration from this field assessment was ca. 7-fold less than the estimated threshold concentration below which it is anticipated that humans will experience no appreciable risk. This single field fall season evaluation was not performed to definitively specify exposure risks under cover crop practices but does highlight the future need to examine and assess worker exposure to naturally occurring toxicants in US high production agriculture.