Annual/Termination Reports:

[08/26/2011] [07/30/2012] [07/03/2013]

Report Information

Participants

Armbrust, Kevin - Office of the State Chemist, Mississippi; Gan, Jay - UC Riverside; Hebert, Vince - Washington State Agricultural Experiment Station; Jenkins, Jeff - Oregon Agricultural Experiment Station; Brieger, Bob - UC Riverside; Lemley, Ann - Cornell University Agricultural Experiment Station; Miller, Glenn - Nevada Agricultural Experiment Station; Pritsos, Chris - University of Nevada, Reno; Pardini, Ron - Nevada Agricultural Experiment Station; Thomas, John - University of Florida Agricultural Experiment Station

Brief Summary of Minutes

Welcome and introduction:

Chairman Gan opened the meeting and acknowledged the efforts of Chris Pritsos and Glenn Miller in hosting the meeting held at the Granlibakken Conference Center and Lodge, Lake Tahoe. Hosts Chris Pritsos, Glenn Miller together with Ron Pardini welcomed the group. Administrative Advisor, Ron Pardini then provided a brief overview of USDA budget concerns and NIFA leadership changes. Pardini commented that once again, the USDA is looking at significant budget reductions with NIFA competitive grants program taking a 30-40 million hit. To avoid further grant reductions Pardini expressed the need to take better advantage of social media for reporting impacts. Dr. Lemley asked on how formula-based funding could be affected. Pardini responded by stating new funding will be competitive grant based but formula funds will have solid support. Pardini also announced to the group that Dr. Roger Beachy stepped down as Director of NIFA effective May 20 of this year.

Dr. Pardini provided a detailed PowerPoint presentation of how at UNR the College of Agriculture, Biotechnology, and Natural Resources (CABNR) sustained a serious budget cut that caused the loss of administrators, faculty and staff. As a direct result of these cuts, the departments of Animal Biotechnology and Resource Economics were eliminated leaving the departments of Biochemistry and Molecular Biology, Natural Resources and Environmental Sciences (NRES) and Nutrition within CABNR. Although there were painful reductions in faculty, a new department of Agriculture, Nutrition and Veterinary Science (ANVS; with Dr. Pritsos as Chair) and three new undergraduate programs were created. The newly proposed majors include: Agricultural Science, Range Ecology and Management, and Forestry Management and Ecology. Pardini indicated that forging interdepartmental, inter-collegiate and multi-state partnerships will be essential in building resources and effectively carrying out the Land Grant mission and education into the future.


Report review and critique:
The group presented and critiqued technical reports.

Old and new business:

The report review and critique was completed at 4:30 pm on 6/6. Chair Gan requested to continue the meeting to conduct old/new business, elect officers, and discuss location of the 2012 W-2045 meeting. All members concurred.

Old Business:

There was no old business discussed.

New Business:

Committee officers: Chair Gan brought up the need to nominate/elect the secretary for the 2012 W-2045 committee. Dr. Lemley nominated Vince Hebert with Dr. Armbrust seconding. Dr. Rice will be assuming Chair responsibilities.

Next meeting: Potential sites for next years meeting were discussed with Montana being forwarded by various members as a potential location for the June 3-5 2012 W-2045 meeting. Since Dr. Sterling could not be present, Chair Gan will contact Dr. Sterling.

Adjournment: The meeting was adjourned at 4:50 pm, June 6, 2011.


Respectfully submitted,

Vince Hebert for Pam Rice W-2045 Secretary

Accomplishments

Objective 1: Identify, develop, and/or validate trace residue analytical methods, immunological procedures, and biomarkers.<br /> <br /> Residential urban and agricultural pest management produce potential unintended, and even unavoidable chemical exposures, that can increasingly be measured and related to acceptable levels of risk determined by advanced risk characterization methodologies. Pesticides used for flea and tick control on companion animals are also used in crop protection and are therefore subject to aggregate exposure and risk assessment. Use of fipronil topical pet products on dogs and cats introduces low level residues into residences. Scientists from University of California - Riverside performed distribution and fate studies of fipronil on pets and in residences to evaluate potential determinants of human exposure. Fipronil and desulfinyl fipronil, fipronil sulfone and fipronil sulfide were measured on hair clippings and brushed hair. The derivatives usually represented <10% of fipronil applied. Cotton gloves worn over impervious nitrile gloves, cotton cloths placed indoors in locations frequented by pets, and cotton socks worn by residents as direct dosimeters collected fipronil and its derivatives above in low amounts during 4 week study periods. Urine biomonitoring following acid hydrolysis or beta-glucuronidase treatment did not reveal significant excretion of biomarkers at ppb levels. The human exposure potential of fipronil is low relative to levels of health concern.<br /> <br /> The impacts of oil released into the Gulf of Mexico from the explosion and sinking of the Deepwater Horizon on April 22nd, 2010 were assessed on seafood collected from the Mississippi gulf coast. Scientists from the Mississippi State Chemical Laboratory (MSCL) have been providing expedited analysis on seafood samples in an ongoing concerted effort with the Mississippi Department of Marine Resources and the Mississippi Department of Environmental Quality. Approximately 379 samples of fish, crabs, shrimp and oysters were collected and analyzed for PAH content from May, 2010 to January, 2011. Although PAHs were detected in every sample collected, no sample contained residues exceeding Levels of Concern (LOC) under the Protocol for Reopening state and federal waters for recreational and commercial fishing following the oil spill. Levels detected in oysters were similar to those detected in oysters collected and analyzed by NOAA prior to the oil spill and were also similar to levels measured in common processed and commercial foods purchased at local grocery stores and restaurants. These data are currently being used by the state of Mississippi, FDA and NOAA to communicate that 1) the most dangerous chemicals known in oil were not found at levels in seafood to cause harm 2) that levels found in seafood were similar to those in samples collected before the oil spill and that commonly are found in samples collected nationally and that 3) these are not new and novel toxic chemicals and are the same chemicals to which the public is exposed everyday in the foods they eat.<br /> <br /> Objective 2: Characterize abiotic and biotic reaction mechanisms, transformation rates, and fate in agricultural and natural ecosystems.<br /> <br /> The Salton Sea is the largest man-made lake in California and the terminal destination of agricultural drainage water from a vast agricultural production area. Planned mitigation and management practices are expected to cause the receding of water level and making the Sea even more inhabitable for fish and wildlife. Species conservation habitats (SCHs) are proposed to be built in exposed playas and sustained with water from the drainage rivers. To select sites for constructing such SCH ponds, it is critical to know the spatial distribution of legacy pesticides and other contaminants in the sediment. Scientists from University of California  Riverside participated in a project supported by California Department of Water resources (DWR) to survey pesticide distribution in areas around the mouth of Alamo River and New River. Results show that DDE was the predominant legacy pesticide contaminant and its distribution was concentrated the river mouth, where about 25% of the sediment samples exceeded the probable effect level (31.3 ¼g/kg) established for total DDE. The levels of DDE also displayed an inverse vertical pattern, with the lower layer containing higher levels, reflecting historical use and deposition. Areas away from the river mouths were generally less contaminated with DDE and other organochlorine pesticides. This information will be useful for successful implementation of SCHs to restore the ecosystem benefits of the Salton Sea.<br /> <br /> Current monitoring data and modeling efforts are inadequate to conduct a robust evaluation of the potential risks to aquatic life associated with pesticide use practices. In formulating risk management strategies, EPA and others address uncertainty by using models driven by conservative assumptions regarding pesticide use and environmental fate. While this approach to dealing with uncertainty in risk assessment is deemed appropriate by many in formulating policies that restrict pesticide use, such an approach may have limited usefulness in informing stakeholders in need of decision aids to guide the selection of practices that meet both production and environmental protection goals. To address this scientists from Oregon State University  Corvallis are using the Soil and Water Assessment Tool (SWAT) to engage local agencies and producers to develop a better understanding of the relationship between agronomic and other land use practices and pesticide surface water loading in Zollner Creek watershed. Expected outcomes are the adoption of crop management, IPM practices, and mitigation measures that meet production goals and result in a reduction in surface water loading of high risk pesticides.<br /> <br /> Volatilization of fumigants and other pesticides is an important consideration for determining loss from treated fields. Scientists from the University of Nevada  Reno developed a relatively simple method for estimating loss of fumigants that requires only simple parameters for estimating volatilization. These include soil adsorption coefficients, depth of application, water solubility and vapor pressure. Emission rates derived from the linear correlation were used as input to an atmospheric dispersion model to estimate concentrations of fumigants in air at various downwind distances and the results were compared with concentration values measured in the field near sources. The fumigant correlation along with an atmospheric dispersion model can be used as a rapid screening method by regulatory and enforcement agencies for exposure and risk assessment. <br /> <br /> 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 investigated as successful methods to remediate environmental pollutants in water, and Fenton treatment has been extensively applied to degrade environmental pollutants. Fenton and modified Fenton reactions use a metal catalyst to generate hydroxyl radicals from hydrogen peroxide with various methods being used to deliver the catalyst into the reaction system. Fenton reactions using nano-magnetite as the iron source is being studied as 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 must be understood to provide the basis for field applications. Scientists from Cornell University have reported the successful removal of 4,6-dinitro-o-cresol (DNOC) using nano-magnetite (Fe3O4) as the iron source and cathodic Fenton generation of hydrogen peroxide. The effects of different DNOC initial concentrations, pH values and nano-magnetite quantities on the degradation rate of DNOC were also examined. The results showed that a lower DNOC initial concentration and a lower pH led to faster degradation of DNOC. It was also observed that the amount of nano-magnetite affected the degradation rate at lower pH while having no influence at neutral pH. The combination of nano-magnetite and cathodic Fenton provides a fast way to degrade organic contaminants with readily available materials. Furthermore, magnetite is more stable, reusable and easy to separate compared to ferrous salt and other iron rich minerals.<br /> <br /> Objective 3: Determine adverse impacts from agrochemical exposure to cells, organisms, and ecosystems.<br /> <br /> 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). Scientists at the University of Nevada - Reno have developed the homing pigeon model to study these exposures in avian species. Birds were exposed to control or methylmercury containing water and flight time was monitored. Following experimental flights, tissues were collected to assess mercury concentrations. Increases in time of flight, tissue mercury concentrations, and tissue/body weight ratios were seen as a result of methylmercury exposure. Water consumption was also monitored throughout a series of experiments in order to gain knowledge as to the drinking behavior of these birds on flight and non-flight days and better understand rates of consumption necessary for NRDA development. Significant differences were observed based on flight activity. These data suggest migrational impairment from ingestion of water from a contaminated area is a very reasonable scenario, and water consumption rates used in determining migratory bird exposure to contaminants in their drinking water for the purposes of developing NRDAs need to take into account flight status.<br /> <br /> <br /> Objective 4: Develop technologies that mitigate adverse human and environmental impacts.<br /> <br /> The EPA Office of Pesticide Programs (Agency) is basing its recent metam sodium (MS) fumigant risk mitigation decision on a flexible approach which is protective to bystanders and allows growers to make site-specific fumigant application method choices. A 10% field set-back distance credit is being considered by the Agency for MS applications conducted at or below 70oF when measured at a soil depth of 3 inches for all surface and soil incorporation fumigant application practices. In the Pacific Northwest (PNW) field fumigations occur during the cooler late fall-early spring months, often at and below 60oF. A question raised by the PNW potato commodity groups/commisions was should field fumigations conducted at 60oF or less be given greater buffer zone credit relief? Scientists from Washington State University  TriCities simulated a series of worst-case pre-plant potato surface applied chemigation conditions to investigate the influence of soil temperature on methylisothiocyanate (MITC) off gassing. The series of six incremental temperature flux examinations (2, 4, 7, 13, 21, and 32oC) showed conversion time of MS to MITC and subsequent MITC peak flux and cumulative surface emissions were associated with soil temperature. The MITC soil column emission data also indicates large scale surface sprinkler head and center pivot fumigations conducted at traditional (40 GPA) and higher fumigant application rates can result in appreciable surface cumulative MITC field losses within days of surface application irrespective of varying soil temperature conditions. Further reduction consideration in field set-back distance will be economically beneficial but could adversely impact air quality and bystander public health. Understanding the influence of soil temperature on MITC off-gassing will be especially important where fumigated field edges exist near dwellings, near or at residential/commerce interfaces, or in close proximity to difficult to evacuate locations.<br /> <br /> The muck soils of the north shore of Lake Apopka, near Orlando, Florida, USA are ideally suited for agriculture; hence, these soils have been exposed to a wide variety of agrochemicals. These muck soils are high in organic matter, inorganic nutrients, and water content. Some of the more recalcitrant organochlorine pesticides, such as DDT and its degradation products DDD and DDE, have persisted in this soil for over three decades. Scientists from the University of Florida  Gainesville are investigating in situ bioremediation of DDx (DDE, DDD, and DDT) at Lake Apopkas North Shore Restoration Area (NSRA) following the typical design of starting small and working towards larger pilot tests. Previously, a series of microcosm experiments using approximately 100 grams of soil were conducted to identify potential treatments and microorganisms that could degrade DDx. These preliminary optimization results using small bench scale tests were used to design and implement larger mesocosm experiments that used 128.5 kilograms of contaminated muck soil. These experiments investigated various bioremediation strategies involving white rot fungi. The ultimate aim is the economical bioremediation of 9,300 hectares of contaminated soil, thus allowing the state-acquired land to be developed for the public good.<br />

Publications

Impact Statements

1. The data in this report represent scientific investigations to understand the fate of pesticides and contaminants in the environment, to quantify contaminant concentrations and potential routes of exposure, and to provide information and describe mechanisms important for residue mitigation and remediation. These discoveries will facilitate the development of technologies that can improve pest management and minimize adverse human and environmental impacts.

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Report Information

Participants

Cathleen J. Hapeman, USDA-Agricultural Research Service, Beltsville MD
Vince Hebert, Washington State Agricultural Experiment Station
Jeff Jenkins, Oregon Agricultural Experimental Station
Ann Lemley, Cornell University Agricultural Experiment Station
Glenn Miller, Nevada Agricultural Experiment Station
Chris Pritsos, University of Nevada
Ron Pardini, Nevada Agricultural Experiment Station Director
Robert Peterson, Montana Agricultural Experiment Station
Pam Rice, USDA-Agricultural Research Service, University of Minnesota
Maria S. Sepúlveda, Purdue University Agricultural Experiment Station
Tracy Sterling, Montana State University
John Thomas, University of Florida Agricultural Experiment Station

Brief Summary of Minutes

Accomplishments

Objective 1: Identify, develop, and/or validate trace residue analytical methods, immunological procedures, and biomarkers<br /> <br /> 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.<br /> <br /> 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. <br /> <br /> 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.<br /> <br /> Objective 2: Characterize abiotic and biotic reaction mechanisms, transformation rates, and fate in agricultural and natural ecosystems<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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. <br /> <br /> Objective 3: Determine adverse impacts from agrochemical exposure to cells, organisms, and ecosystems<br /> <br /> 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.<br /> 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.<br /> <br /> 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.<br /> <br /> Objective 4: Develop technologies that mitigate adverse human and environmental impacts<br /> <br /> 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.<br /> <br /> 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. <br /> <br />

Publications

Impact Statements

1. The information reported herein further advances our understanding of the fate and movement of pesticides and organic contaminants in air, water and land surfaces. The amalgam of these federal-state research efforts combined with state experimental station outreach will facilitate the development and adoption of technologies that can improve pest management while minimizing adverse human and environmental impacts.

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Report Information

Participants

Jay Gan, University of California Agricultural Experimental Station
Vince Hebert, Washington State Agricultural Experiment Station
Jeff Jenkins, Oregon Agricultural Experimental Station
Ann Lemley, Cornell University Agricultural Experiment Station
Glenn Miller, Nevada Agricultural Experiment Station
Ron Pardini, Nevada Agricultural Experiment Station Director
Robert Peterson, Montana Agricultural Experiment Station
Maria S. Sepúlveda, Purdue University Agricultural Experiment Station

Brief Summary of Minutes

Accomplishments

Objective 1: Identify, develop, and/or validate trace residue analytical methods, immunological procedures, and biomarkers<br /> <br /> Silver nanoparticles (Ag NPs) are gaining popularity as bactericidal agents in commercial products; however, the mechanisms of toxicity (MOT) of Ag NPs to other organisms are not fully understood. Indiana SAES scientists examined if differences exist in MOT induced by ionic Ag+ and Ag NPs in Daphnia magna, by incorporating a battery of traditional and novel methods. Daphnia embryos were exposed to sublethal concentrations of AgNO3 and Ag NPs (130650 ng/L), with uptake of the latter confirmed by confocal reflectance microscopy. Mitochondrial function was non-invasively monitored by measuring proton flux using self-referencing microsensors. Proton flux measurements revealed that while both forms of silver significantly affected proton efflux, the change induced by Ag NPs was greater than that of Ag+. This could be correlated with the effects of Ag NPs on mitochondrial dysfunction, as determined by confocal fluorescence microscopy and JC-1, an indicator of mitochondrial permeability. However, Ag+ was more efficient than Ag NPs at displacing Na+ within embryonic Daphnia, based on inductively coupled plasma-mass spectroscopy (ICP-MS) analysis. The abnormalities in mitochondrial activity for Ag NP-exposed organisms suggest a nanoparticle-specific MOT, distinct from that induced by Ag ions. The Indiana SAES scientists propose that the MOT of each form of silver (of Ag+ and Ag NPs) are complementary, one taking place at the surface of the embryo wall, and the other within mitochondria, and can act in synergy to produce a greater overall toxic response.<br /> <br /> Objective 2: Characterize abiotic and biotic reaction mechanisms, transformation rates, and fate in agricultural and natural ecosystems<br /> <br /> Pollution of water and soil in the environment by animal antibiotics has become a widespread concern for water quality and as a source of serious hazards for humans and other living species. Manganese (III/IV) oxides are naturally occurring minerals that are widely distributed in surface water, sediment and soil. With their abundance in the environment, particularly in water bodies, New York Cornell experimental station scientists are evaluating the oxidizing properties of manganese oxides for human-veterinary medicines that do not completely metabolize in the body and can be released in the environment. This study reports the use of synthetic cryptomelane (KMn8O16) prepared with the transition metal MoO3 in oxidizing Ciprofloxacin (CIP), a fluoroquinolone antibiotic commonly found in wastewater. This study 1) characterized effectiveness of synthetic cryptomelane and its doped MoO3 (with other metal transition derivatives) for CIP removal from aqueous solution, 2) optimized treatment conditions, and 3) modeled the kinetic process and propose the degradation pathways of CIP. X-ray powder diffraction (XRD) patterns, scanning electron microscopy (SEM), and surface measurements by Brunaure-Emmett-Teller (BET) all lend support that cryptomelane-type crystals are principally responsible for the observed kinetics. FTIR and Raman spectra indicate that reactions should takes place on the oxide surface. Optimal treatment conditions were obtained at pH 3 with molar ratio [9% Mo/ KMn8O16]:[CIP] e 50. Under such conditions, more than 90% CIP can be removed in 30 minutes. The degradation kinetics can be modeled by a modified first order rate with introduction of a retardation factor ± (R2> 0.98). Analysis of degradation products indicated that oxidation takes place mainly on the piperazine ring of CIP. The oxidation products are less potent compared to the parent compound. However, the quinolone core structure remained unattacked and the possibility of residual antibacterial activity cannot be ruled out.<br /> <br /> The most commonly applied fumigant in the U.S. is now metam sodium, with approximately 50% use as a pre-plant soil treatment for potatoes. The actual chemical that controls a variety of pests following application of metam sodium is the transformation product, methyl isothiocyanate (MITC). MITC is volatile and a large percentage of this chemical volatilizes from treated fields into the atmosphere. It has a strong odor, and appreciable toxicity, so measurement of exposure to this chemical is important. In addition, the major conversion product of MITC in the atmosphere is the very toxic compound, methyl isocyanate (MIC). Under controlled laboratory conditions, the gas phase reaction of hydroxyl (OH) radicals with MITC and MIC was examined by Nevada experimental station scientists using static relative rate techniques in 100 L Tedlar air sampling bags over a 30 minute period. Gas phase MITC, MIC and OH reference compounds (xylene and toluene) were quantified by solid phase microextraction-GC/MS. The rate constants obtained are: MITC: 15.36 x 10-12 cm3 molecule-1 s-1 and for MIC: 3.62 x 10-12 cm3 molecule-1 s-1. Photolysis is also observed when MITC is exposed to midsummer sunlight with a half-life on the order of 30 hours of continuous exposure (including nighttime). While direct comparisons using these results are only approximate, the results of the previous study on photolysis of MITC, and the present study indicate that OH reactions are about twice as important as direct photolysis for transformation of MITC. The molar conversion of MITC to MIC for hydroxyl radical reactions is 67% ± 8%, which indicates that MIC is the primary product of the MITC-OH reaction in the gas phase. The average half-lives of MITC and MIC in the atmosphere are estimated to be 15.7 hr and 66.5 hr, respectively. Results obtained in this work demonstrate that MIC is a primary transformation product of MITC and it disappears approximately 4 times slower than MITC in the presence of OH radicals. Due to the large consumption of metam sodium in the U.S. agriculture and the important health concern of MIC, this study will provide useful information for exposure assessments for use of metam sodium and other pesticides in which MITC serve as the active fumigant. <br /> <br /> As water scarcity is exacerbated by urbanization and climate change, especially in arid and semi-arid regions, treated wastewater is increasingly an attractive alternative source of water for agricultural irrigation. However, many man-made chemicals, including pharmaceutical and personal care products (PPCPs) are present in the finished effluent of wastewater treatment plants. When treated wastewater is used for agricultural irrigation, the trace contaminants have the potential to enter and accumulate in food crops. PPCPs are emerging contaminants that are extremely diverse in properties. The possible consequences from continued dietary food uptake of many PPCPs require greater attention. Under hydroponic conditions, California Agricultural Experiment Station scientists have examined root uptake and plant translocation of commonly occurring PPCPs in vegetables. A total of 20 PPCPs with varying Kow or pKa values were included, and four staple vegetables, i.e., lettuce, spinach, cucumber, and pepper, were grown hydroponically in nutrient solutions containing PPCPs at 0.5 or 5 ¼g L-1. The annual exposure values ranged from 0.08 to 154 ¼g for lettuce and 0.04 to 354 ¼g for spinach for an average, 70 kg individual residing in the United States suggesting that direct human risk would be negligibly small from this exposure pathway for the PPCPs considered in this study. The overall low root accumulation of acidic and weakly hydrophobic compounds reported in this study may be attributed to the significant ionization and limited lipophilic sorption. In comparison, neutral PPCPs usually contributed to greater accumulation in plant roots but lesser to tissue translocation. Root crops may have greater potential for PPCP dietary exposure. Laboratory hydroponic growing conditions and the higher 5 ¼g L-1dosing concentration should reflect worst-case exposure. Further PPCP accumulation waste water vegetable studies should be evaluated under actual field growing conditions using representative cultivation and management conditions.<br /> <br /> Objective 3: Determine adverse impacts from agrochemical exposure to cells, organisms, and ecosystems<br /> <br /> The use of pyrethroid insecticides has increased substantially throughout the world over the past few decades as the use of organophosphorous, carbamate, and organochlorine insecticides is being phased out. Pyrethroids are the most common class of insecticides for ultralow- volume (ULV) aerosol applications used to manage high densities of adult mosquitoes. This group of insecticides are highly nonpolar chemicals that have low water solubility and volatility, high octanol:water partition coefficients. As such, pyrethroids have a high affinity to bind to sediment and dissolved organic matter. Several studies have shown that the presence of dissolved organic material significantly decreases the bioavailable concentration of pyrethroids and the toxicity to aquatic organisms. Pyrethroids are highly toxic to nontarget organisms such as certain aquatic organisms, and there have been concerns about the effect of applications of ULV insecticides on these organisms. To date, only deterministic ecological risk assessments have been conducted for insecticides used for management of adult mosquitoes. The models used for estimating environmental concentrations from ULV applications are not validated or appropriate. To address the uncertainties associated with the risks of ULV applications and the contradictory findings of other ecological risk assessments, Montana Agricultural Experiment Station (MAES) scientists performed a probabilistic aquatic ecological risk assessment using actual environmental deposition on surfaces to estimate permethrin concentrations in water. This study is the first ecological risk assessment for pyrethroids to quantitatively integrate the reduction in bioavailability resulting from the presence of dissolved organic matter. As part of the risk assessment, MAES scientists incorporated a species sensitivity distribution to take into account the differences in toxicity for different invertebrate and vertebrate aquatic species and found that the 95th percentile estimated concentration would result in less than 0.0001% of the potentially affected fraction of species reaching the lethal concentration that kills 50% of a population. The results of the present study are supported by the weight of evidence that pyrethroids applied by ground-based ULV equipment will not result in deleterious effects on aquatic organisms.<br /> <br /> Objective 4: Develop technologies that mitigate adverse human and environmental impacts<br /> <br /> Occupational and residential exposures to pesticide residues present significant risks to human health in developing countries, especially in rural agricultural communities. Due to insufficient regulation at the national level highly toxic pesticides, many no longer registered in the developed world, are routinely used. Rural farmers frequently lack the education required to read pesticide use labels and warnings. Personal protective clothing and well maintained application equipment are likely to be unavailable. Training is infrequent or absent. Entire families are often involved in agriculture creating subpopulations that are at higher risk such as children, women of reproductive age. The GEF-PRM project has partnered scientists from Oregon State University and the UN Food and Agricultural Organization with Environnement et Développement du Tiers Monde (ENDA), a West African NGO with over 30 years of experience in community based participatory research to conduct community surveys rural communities. The survey, consisting of 190 questions, was administered by ENDA. Approximately 300 households in 6 rural communities situated along the Senegal River were surveyed. Those conducting the survey were selected from within the communities and trained in survey techniques. The use of personal protective equipment including eye protection, and hand washing was not prevalent. Entire families are often involved in agriculture creating subpopulations that are at higher risk such as children, women of reproductive age, the elderly and individuals suffering from chronic illness or malnutrition. Of particular concern was re-entry into treated fields by women and children. Survey results suggest that when pesticide residues are high due to overuse, community members are further exposed through their diets and the possibility of exposure to pesticide residues is present in a wide variety of activities and situations. Data at this level of resolution allows the GEF-PRM project to perform community specific risk assessments and allows comparison of health risks within and between communities. Study results will be returned to the community to allow members to design and implement improvements that will make their community safer. Results will also be made available to regional and national government agencies to use in regulatory and policy decisions.<br /> <br /> A residential air monitoring program was conducted in south Franklin County, WA in the fall of 2012 to assess metam sodiums (MS) biologically active byproduct methyl isothiocyanate (MITC) in ambient air near five residential and commercial structures during the fall potato fumigation season. Twelve-hour time weighted averaged (TWA) samples were collected at the five sites, three days (Monday, Wednesday, and Friday) per week starting October 1 through October 31. Air samples were collected more frequently, at 4-hr TWA intervals, October 22-26 when irrigation water was cut off. This study also provides, for the first time, residential inhalation exposure information for methyl isocyanate (MIC), a volatile and toxic atmospheric transformation product of MITC. Air sampling for MIC was also monitored at similar intervals during this irrigation cut-off period. The monthly 12-hour time TWA MITC air concentrations ranged from quantifiable (>0.01 ppb) to 20 ppb, below the EPA-Office of Pesticide Programs level of concern (LOC) of 22 ppb. During the October 22-26 irrigation cut-off period, 4 hr TWA MITC air concentrations ranged from below quantifiable to 88 ppb. The 88 ppb air monitoring reading was a single observation we recorded above the EPA LOC among 108 sampling events. MIC was reported in 68 of the 72 air samples taken during the irrigation cut-off week at concentrations greater than the methods limit of quantification (0.035 ppb) and ranged from 0.05 to 1.9 ppb. Given the estimated 12-18 hr atmospheric half-life for MIC to form from photolysis of MITC, this residential air information affirms that it is reasonable to anticipate MITC and MIC will coexist in breathing air during the soil fumigation season. Roughly, a10:1 ratio of MITC to MIC air concentrations were observed over this one week air sampling period. These residential air fumigant observations are in alignment to an earlier 1995 Cal EPA MITC-MIC near-field shank field assessment, which reported proportionally similar MITC to MIC air concentrations and supports the need for a better understanding the combined contributions of MITC with MIC when assessing potential risks from residential fumigant inhalation exposure.<br />

Publications

Impact Statements

1. Judicious use of agrochemicals and other man-made chemicals will demand practical knowledge of their fate and effects in agricultural and natural ecosystems. The directed multi-institutional federal-state and interdisciplinary research efforts combined with state experimental station outreach reported herein facilitates the development and adoption of economic technologies that improve pest management while minimizing adverse human and environmental impacts.

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