Brief Summary of Minutes of Annual Meeting

Objective 1: Identify, develop, and/or validate trace residue analytical methods, immunological procedures, and biomarkers.

Scientists at Mississippi State University developed a new direct gas chromatography procedure (headspace solid phase microextraction) for the quantitative determination of methanol in biodiesel. The analysis was performed by exposing a Carboxen-Polydimethylsiloxane SPME fiber assembly to the headspace of biodiesel samples. The gas chromatography method used a HP-5 capillary column and a flame ionization detector. A polynomial relationship was observed between the methanol concentration and its peak area. This method showed good reproducibility (average relative standard deviation 7.06%) and recovery (average recovery 100.2%).

Scientists at University of California Riverside, in collaboration with California Department of Pesticide Regulation and Pyrethroid Working Group, conducted research on approaches to characterize the bioavailability of pyrethroid residues in sediments. Pyrethroids are highly hydrophobic, and toxicity from sediment-borne pyrethroids is expected to depend closely on their desorption rate. In the present study, we evaluated the effect of aging on desorption kinetics of sediment-borne pyrethroids. Two sediments spiked with four pyrethroids were incubated for 7, 40, 100, and 200 d at room temperature. Desorption measured using sequential TenaxÒ extractions was well described by a three-compartment model. The estimated rapid desorption fraction (Frapid) decreased quickly over time and was accompanied by an increase of the very slow desorption fraction (Fvs). The aging effect on desorption kinetics followed a first-order model, with half-lives for the decrease in Frapid for all four pyrethroids in both sediments ranging from two to three months. When coupled with degradation, the estimated half-lives of the rapidly desorbing fraction (thus, the potentially bioavailable concentration) were £ two months for all four pyrethroids. Two field-contaminated sediments displayed distinctively different desorption kinetics. The sediment with fresh residues exhibited rapid desorption, while the other sediment containing aged residues was highly resistant to desorption. The observation that desorption of pyrethroids decreased quickly over contact time implies that the bioavailability of sediment-borne pyrethroids may diminish over time, and that the use of non-selective extraction methods may lead to overestimation of the actual sediment toxicity from pyrethroid contamination.

There has been a distinct decrease in fur seal (Callorhinus ursinus) population noted in their primary breeding grounds in the Bering Sea. Environmental pollution is a prime suspect. Scientists at University of Hawaii measured the concentrations of polychlorinated biphenyl (PCB) congeners and organochlorine pesticides (OCPs) in eight tissues of fur seals from St. Pauls Island to provide a better perspective of congener distribution and use various congener specific metrics of different toxicities. Concentrations of 145 PCB congeners 12 OCPs or their metabolites were measured with gas chromatography-ion trap mass spectrometry in eight different tissues of 10 male northern fur seals. The mean concentrations of OCPs ng/g wet weight (ww) were found to be 855 in blubber, 61.9 in heart, 46.5 in liver, 41.8 kidney, 23.9 in brain, 19.4 in muscle, 16.4 reproductive tissues (reprod), and 8.8 in lung. Among the OCPs analyzed, p,p-DDE is dominant in all tissues, accounting for more than 60% of the total concentration of OCPs. Among the 4 hexachlorocyclohexane (HCH) isomers, b-HCH is the main isomer in all tissues except brain where a-HCH is the dominant isomer and accounts for more than 30% of the OCPs analyzed. The mean concentrations of PCBs ng/g ww were 578 in blubber, 47 in heart, 34 in liver, 31 in kidney, 13 in muscle, 16 in reprod, 10 in brain, and 5 in lung. Dioxin-like toxic equivalent (PCB-TEQs) showed moderately high values except in brain and lung. Neurotoxic equivalent (NEQ) analyses showed a similar distribution with brain and lung having low but possibly toxic levels and other tissues much higher levels. Enzymatic activity-based classification indicated mixed oxidase inducers present in high concentrations in most tissues while biological action-based grouping indicated problematic estrogenic activity in reproductive tissue for males. Analyses of 145 PCBs and toxicity grouping evaluation suggest that PCB contamination could cause the decrease in population of northern fur seals.

Scientists at University of Florida conducted field studies in Florida to compare the effect of three different plastic films on subsurface distribution and surface emissions of (Z)- and (E)-1,3-dichloropropene (1,3-D) and chloropicrin (CP) after conventional chisel injection of Telone C35 to field beds using N2 or CO2 as propellant/dispersant. The three plastic films were black virtually impermeable film (VIF), metallic polyethylene (PE), and blue PE. All treatments were carried out in three replications. Previous studies have shown that the three VIF covered beds had a better capacity to retain (Z)- and (E)-1,3-D than all the PE covered beds. The use of CO2 with Telone C35 provided quicker and deeper distribution initially compared to application by N2 pressurization. The deeper distribution of Telone C35 components found with CO2 application may have lowered the initial concentration of Telone C35, but it did not appreciably alter the disappearance rate of the three compounds. Although the faster vertical distribution in the bed of the Telone C35 by CO2 did enhance volatilization of the three compounds into the atmosphere compared to volatilization of similar reduced rate applied by N2, the total amount volatilized from the carbonated fumigant beds was still lower than the total amount volatilized to the atmosphere by full rate of Telone C35 using N2.

Objective 2: Characterize abiotic and biotic reaction mechanisms, transformation rates, and fate in agricultural and natural ecosystems.

Scientists at University of Cornell advanced the application potential of anodic Fenton treatment through a study on the adsorption and degradation of carbaryl, mecoprop and paraquat were studied in an Swy-2 Na+-montmorillonite clay slurry. Adsorption isotherms for these three agrochemicals were obtained at given experimental conditions. The d spacing (d001) of the clay layer before and after adsorption or degradation was measured by X ray diffraction (XRD). Based on the change of d spacing, molecular disposition at the clay interlayer was inferred: both mecoprop and paraquat form a monolayer sitting flat and parallel to the clay siloxane surfaces. Results show that, due to different adsorption mechanisms, the adsorption effect on chemical degradation by anodic Fenton treatment (AFT) varies with pesticide: strong and tight adsorption of paraquat at the clay interlayer protects paraquat from being attacked by hydroxyl radicals; loosely adsorbed carbaryl or mecoprop is readily degraded. XRD analysis clearly indicates that AFT is capable of effectively degrading interlayer non-cationic organic chemicals that are not usually available for biodegradation.

Scientists at University of Nevada Reno continued the examination of photochemical processes on arid land soil surface, particularly the photochemical and thermal fixation of atmospheric nitrogen on arid lands soils and titanium dioxide. Photochemical fixation of nitrogen on soils was established over 20 years ago, but has received less attention in recent years. During the previous year we have provided strong evidence that nitrogen is also fixed thermally on titanium dioxide and soils to produce nitrate. On titanium dioxide, nitrate production was observed at 70oC, with a maximum rate of production at approximately 200oC. At temperatures above 400oC, some production of nitrate was observed, but the rate of loss of nitrate increased substantially. The pH of an aqueous rinsing of thermally treated titanium dioxide was lower than the controls, consistent with the production of nitric acid. Addition of base (either sodium hydroxide or potassium hydroxide) increase the rate of production substantially. Soils were generally less active in nitrate production, and varied with the type of soil used. USDA-ARS scientists in St. Paul, MN, studied runoff transport of pesticides from irrigated turf systems and evaluated mitigation options. The use of pesticides in highly managed turf systems has raised questions concerning the contribution of runoff from managed turf. Experiments were designed to measure the quantity of pesticides transported with runoff from turf plots maintained as a golf course fairway, and to evaluate the ability of management practices to reduce the transport of applied chemicals with runoff. Half of the plots were managed with solid tine aerification while the remaining plots received hollow tine aerification. Management practices were initiated 2 and 63 days prior to chemical application and simulation of precipitation. Runoff volumes and quantities of pesticides transported with runoff were reduced in fairway turf plots managed with hollow tines relative to solid tines. Similar trends in pesticide loads between the two aerification practices were observed when the duration of time between management practice and runoff increased from 2d to 63d; however, the difference between pesticide loads associated with the two aerification practices declined with time. Understanding chemical transport with runoff and identifying strategies that reduce off-site transport of applied chemicals will increase their effectiveness at intended sites of application and will minimize undesirable impacts to surrounding areas.

Objective 3: Determine adverse impacts from agrochemical exposure to cells, organisms, and ecosystems.

Pyrethroids are increasingly used for pest control as the use of many organophosphate products is restricted. Scientists at Oregon State University examined the effect of dietary esfenvalerate uptake in aquatic insects representing different functional feeding groups. We utilized three field-collected aquatic insect species: a grazing scraper Cinygmula reticulata McDunnough (Ephemeroptera: Heptageniidae), an omnivorous filter feeder Brachycentrus americanus Banks (Trichoptera: Brachycentridae), and a predator Hesperoperla pacifica Banks (Plecoptera: Perlidae). Laboratory-cultured algae were pre-exposed for 24h to esfenvalerate concentrations of 0, 0.025, 0.05, and 0.1 ¼g/L and provided to two C. reticulata age classes, small and final-instar nymphs. Reduction in small nymph growth was observed following three weeks feeding on algae exposed to 0.05 and 0.1 ¼g/L esfenvalerate, and the highest dietary exposure reduced egg production in final-instar nymphs. The diet for B. americanus and H. pacifica insects consisted of dead third-instar Chironomus tentans larvae; these were pre-exposed to esfenvalerate concentrations ranging between 0.1 and 1.0 ¼g/L. Consumption of the larvae exposed to 0.5 to 1.0 ¼g/L esfenvalerate caused case-abandonment and mortality in B. americanus caddisfly larvae. Although H. pacifica nymphs readily consumed esfenvalerate-exposed larvae, no adverse effects of consumption were observed during the course of this study. Further, there was no evidence of esfenvalerate-induced feeding deterrence in any of the species tested, suggesting that aquatic insects may not be able to distinguish between pyrethroid-contaminated and uncontaminated food sources.

Hydrogen cyanide (HCN) fumigation of closed transport trailers protects citrus from California red scale and other surface pests of citrus. California red scale is a serious pest that can be transported on oranges, lemons, grapefruit and other citrus. Transmission of red scale from California to citrus growing regions of Arizona has been a significant concern since the 1930s. Scientists at University of California Riverside studied HCN residues following HCN fumigation of transport trailers at the maximum rate (1-ounce sodium cyanide per 100 ft3). Standard procedures produce HCN residues of less than 1 ppm in whole fruit at the primary distribution center in Phoenix, AZ. USEPA Method #335.2, a spectrophotometric procedure with a Minimum Reportable Level of about 0.04-0.05 ppm, analyzed residues. The oranges (n = 20) contained 0.69 ± 0.29 ppm HCN and the lemons (n = 10) contained 0.78 ± 0.38 ppm HCN at the Arizona distribution center. The citrus residue tolerance is 50 ppm. The citrus residue is of neither of regulatory nor health significance. The majority of metabolomic studies used in ecotoxicology have implemented 1H NMR analysis. Despite constant improvement, major limitations of NMR-based techniques include relatively low sensitivity that results in an examination of a limited number of metabolites. Scientists at Purdue University explored an alternative approach by using liquid or gas chromatography (GC) for separation of metabolites and mass spectrometry (MS) for their quantification and identification. The objective of the study was to develop a two dimensional GC coupled with time of flight MS (GCxGC/TOF-MS) coupled with multivariate analysis to compare metabolite profiles of Diporeia under different environmental conditions. We compared metabolite profiles between Diporeia collected from Lake Michigan (declining populations) to those residing in Lake Superior (stable populations), and also between Diporeia exposed to a chemical stressor (atrazine) and controls. Overall, 76 and 302 total metabolites were detected from the lake comparison and atrazine studies, respectively. Many of the identified metabolites included fatty acids, amino acids, and hydrocarbons. Furthermore, we observed unique and almost non-overlapping metabolite profiles in both studies. In conclusion, we established the feasibility of using GCxGC/TOF-MS for detecting metabolites as well as developed software to align and merge chromatographic peaks to compare metabolite differences between invertebrate groups sampled under different environmental conditions. This ability to detect unique metabolite profiles under different environmental conditions will increase our understanding on the physiological processes and whole-organism responses occurring as a result of exposure to different environmental stressors.

Geographic Information Systems (GIS) can be utilized to store, display, and analyze spatial data. Spatial scan statistics can be utilized to investigate spatial and temporal clustering in epidemiological studies. Scientists at the Oregon State University analyzed five years of PCC data to test whether there are significant geographic differences in pesticide exposure incidents resulting in serious (moderate, major, and fatal) outcomes. A Poison Control Center provided data on pesticide exposure incidents for the time period 2001-2005. These data were abstracted to identify the geographic location of the caller, the location where the exposure occurred (residential, workplace, or other), and the medical outcome (no effect, minor, moderate, major effects, death). The results yielded 299 incidents resulting in moderate (n=284), major effects (n=12), or fatalities (n=3). Analysis of these data using spatial scan statistics resulted in the identification of a geographic area consisting of 2 contiguous counties (one urban, one rural) where statistically significant clustering of serious outcomes was observed. The relative risk of a moderate, major, or fatal outcome was 1.9 in this geographic cluster (p=0.0012). Poison Control Center data, GIS, and spatial scan statistics can be effectively utilized to identify geographic clustering of serious incidents involving human exposure to pesticides. These analyses may be useful for public health officials to target preventive interventions. Further investigation is warranted to better understand the potential explanations for geographical clustering, and to assess whether preventive interventions have an impact on reducing pesticide exposure incidents resulting in serious medical outcomes. Application of DNA microarray technology for gene expression profiling to examine cellular and molecular responses of an affected organism to environmental stressors promises a significant advance. In order to develop a cDNA microarray of the aquatic midge (Chironomus tentans), an ecologically important bioindicator species, scientists at Kansas State University sequenced a total of 10,368 clones from a C. tentans cDNA library. The analysis of 10,367 high-quality expressed sequence tags (ESTs) resulted in a total of 2,912 putative transcripts including 2,095 singletons and 817 contigs. These putative transcripts were functionally annotated and sorted into 14 biological process, 17 cellular component, and 10 molecular function categories. Eighty nine of the transcripts likely encode different types of hemoglobin that are involved in the oxygen storage and/or transport. Twenty nine and 11 transcripts putatively encode cytochrome P450 enzymes and glutathione S-transferases (GSTs), respectively. These enzymes play an important role in the biotransformation of toxic chemicals and endogenous substrates in an organism. Further analysis of the 11 GST ESTs revealed that seven enzymes belong to three cytosolic classes (2 in delta, 4 in sigma and 1 in omega), and the remaining four did not come up with proper classifications. Furthermore, these genes appear to be widely expressed in different tissues of C. tentans larvae. These ESTs will be used to develop a DNA microarray for gene expression profiling to examine cellular and molecular responses of midges to various environmental stressors.

Objective 4: Develop technologies that mitigate adverse human and environmental impacts.

South Franklin County, Washington State is currently undergoing rapid residential and commercial growth into traditional large production agricultural lands. There have been public health concerns that residential expansion could contribute to increased risks for human inhalation exposure to agricultural fumigants in this region. The purpose of the 2007 monitoring work herein was to assess if off-target methyl isothiocyanate (MITC) concentrations in residential ambient air exceeded the EPA Office of Pesticide Protection (EPA OPP) human equivalent concentration (HEC) criteria for acute and subchronic residential inhalation exposure. The 2007 air monitoring was conducted in a similar manner to an earlier 2005 MITC residential air study. As in 2005, off-target MITC emissions were monitored at 24-hr periods three times weekly over the fumigation season. However, during the week before the irrigation cut-off in late October, residential air was monitored more intensively at 4-hr instead of 12-hr TWA intervals to better assess possible short-term acute inhalation exposure. The12-hr time weighted averaged (TWA) MITC residue concentrations ranged from detectable (>0.01 ppb) to 12 ppb. An observed TWA 4-hour concentration maximum air concentration of 40 ppb taken days before the Countys irrigation cut-off date appreciably exceeded the EPA OPP acute HEC value of 22 ppb. The seven-week TWA seasonal concentration of 1.5 ppb exceeded the established California EPA subchronic reference exposure level (REL) of 1 ppb but was less than EPA OPP 5 ppb subchronic HEC. The results in this 2007 air monitoring study were comparable to monitoring observations in 2005 and again indicated that MITC residential air concentrations were fairly uniform among all sampling locations within this basin. Moreover, appreciably higher air residues were observed, as in 2005, towards the end of the fumigation season just days before irrigation waters were cut off. It is reasonable to conclude that the shorter 4-hr air interval samplings taken during this later period are a better indication of acute inhalation exposure than from our earlier 12-hour averaged MITC residues over this similar period in 2005.