Brief Summary of Minutes of Annual Meeting

Objective 1: Identify, develop, and/or validate trace residue analytical methods, immunological procedures, and biomarkers 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. 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 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. 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. 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. Objective 3: Determine adverse impacts from agrochemical exposure to cells, organisms, and ecosystems 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. Objective 4: Develop technologies that mitigate adverse human and environmental impacts 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. 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.