Remediation of Fungicide Residues on Fresh Produce by Use of Gaseous Ozone

Ozone fumigation was explored as a means for degrading organic fungicide residues on fresh produce. Fungicides sorbed onto model abiotic glass surfaces or onto grape berries were fumigated separately in a flow-through chamber. Gaseous ozone at a constant concentration of 150 ± 10 ppmv (μL·L–1) selectively oxidized fungicides sorbed to model surfaces. Over 140 min, boscalid and iprodione levels did not change significantly based on a single-factor analysis of variance (ANOVA) at the 95% level of confidence (p = 0.05); however, pseudo-first-order losses resulted in observable rate constants of ozonolysis, kozonolysis (min–1), of 0.0233 ± 0.0029 (t1/2 ≈ 29.7 min), 0.0168 ± 0.0028 (t1/2 ≈ 41.3 min), and 0.0127 ± 0.0010 (t1/2 ≈ 54.6 min) for fenhexamid, cyprodinil, and pyrimethanil, respectively. The relative degradation of fungicides on berries at gaseous ozone concentrations of 900 ± 12 ppmv (μL·L–1) over 2 h was similar to that on glass; decreases in residue concentration were observed for only fenhexamid (∼64%), cyprodinil (∼38%), and pyrimethanil (∼35%) with corresponding kozonolysis (min–1) of 0.0085 ± 0.0021 (t1/2 ≈ 81.5 min), 0.0039 ± 0.0008 (t1/2 ≈ 177.7 min), and 0.0036 ± 0.0007 (t1/2 ≈ 192.5 min). Heterogeneous rate constants of gaseous ozone reacting with a sorbed fungicide, kO3 (M–1·min–1), were calculated for both surfaces and indicate losses proceed ∼15-fold slower on grapes. The kinetics and mechanism of fungicide removal, supported by gas chromatography– and liquid chromatography–mass spectrometry product analyses, is discussed in the context of facilitating compliance with maximum residue level (MRL) tolerances for fresh produce

Nitrosamine Carcinogens Also Swim in Chlorinated Pools

Highly carcinogenic N-nitrosodialkylamine (nitrosamine) disinfection byproducts were quantified in chlorinated swimming pools, hot tubs, and aquaria. N-Nitrosodimethylamine, the most abundant nitrosamine detected, was measured in swimming pools and hot tubs at levels up to 500-fold greater than the drinking water concentration of 0.7 ng/L associated with a one in one million lifetime cancer risk. Temperature, enclosure, amine and nitrite precursor loading, and the use of disinfection schemes with reduced chlorine doses contributed to statistically significant variability in its occurrence. N-Nitrosodibutylamine and N-nitrosopiperidine were also detected but together represented N-nitrodimethylamine at levels comparable to N-nitrosodimethylamine points to a competition between the nitration and nitrosation of amines in chlorinated recreational waters. Since nitrosamines can cause bladder cancer, the significance of our measurements needs clarification with respect to recent epidemiological results that are suggestive of a link between swimming in chlorinated pools and bladder cancer

Flight Bioassay Actual Preference Probabilities.

<p>Actual preference probabilities of paired flight bioassays for mated spotted wing drosophila females responding to host <b>A</b> volatiles (column) when simultaneously exposed to host <b>B</b> volatiles (row).</p

Potential HPI values when weighting coefficients are varied across four studies.

<p>The probability distributions of resultant Host Potential Index values derived from varying the weighting coefficieints (<i>β</i>) in the equation for the individual fruits shows the influence of coefficient weight selection. Vertical lines indicate the mean HPI value of each fruit.</p

Correlation of spotted wing drosophila host volatile response to preference probabilities.

<p>Spotted wing drosophila attraction (i.e., recapture percentage) to host volatiles was evaluated in two-choice horizontal flight chamber bioasssays and correlated to the actual probability of preference, <i>A</i> (Eq. 1)(<i>R</i>² = 0.93, <i>F_(1,5)</i> = 69.09, <i>P</i><0.001). Dashed lines indicate 95% confidence interval for the correlation.</p

Host Potential Summary for Spotted Wing Drosophila.

<p>Row values not connected by the same letter are significantly different (Tukey-Kramer HSD, α = 0.05)</p><p>Summary of results for all four studies examining host potential for spotted wing drosophila.</p

Quantifying Host Potentials: Indexing Postharvest Fresh Fruits for Spotted Wing Drosophila, <i>Drosophila suzukii</i>

<div><p>Novel methodology is presented for indexing the relative potential of hosts to function as resources. A Host Potential Index (HPI) was developed as a practical framework to express relative host potential based on combining results from one or more independent studies, such as those examining host selection, utilization, and physiological development of the organism resourcing the host. Several aspects of the HPI are addressed including: 1) model derivation; 2) influence of experimental design on establishing host rankings for a study type (no choice, two-choice, and multiple-choice); and, 3) variable selection and weighting associated with combining multiple studies. To demonstrate application of the HPI, results from the interactions of spotted wing drosophila (SWD), <i>Drosophila suzukii</i> Matsumura (Diptera: Drosophilidae), with seven “reported” hosts (blackberries, blueberries, sweet cherries, table grapes, peaches, raspberries, and strawberries) in a postharvest scenario were analyzed. Four aspects of SWD-host interaction were examined: attraction to host volatiles; population-level oviposition performance; individual-level oviposition performance; and key developmental factors. Application of HPI methodology indicated that raspberries (<i>^meanHPI_varied</i> = 301.9±8.39; rank 1 of 7) have the greatest potential to serve as a postharvest host for SWD relative to the other fruit hosts, with grapes (<i>^meanHPI_varied</i> = 232.4±3.21; rank 7 of 7) having the least potential.</p> </div

Glucosylated Suspensosides, Water-Soluble Pheromone Conjugates from the Oral Secretions of Male <i>Anastrepha suspensa</i>

A diastereomeric mixture of the glycosylated pheromones (6R)- (1a) and (6S)-β-d-glucopyranosyl 2-(2,6-dimethyl-6-vinylcyclohex-1-enyl)acetate (1b), which we named respectively suspensoside A and suspensoside B, was isolated from the oral secretions of male Caribbean fruit flies, Anastrepha suspensa. The absolute stereochemical configurations were established using microsample NMR instrumentation, chiral gas chromatography, and chemical synthesis utilizing pure enantiomers of anastrephin, (3aS,4R,7aS)- (4a) or (3aR,4S,7aR)-4,7a-dimethyl-4-vinylhexahydrobenzofuran-2(3H)one (4b), as the aglycon precursor

Surface-Catalyzed Transformations of Aqueous Endosulfan

We report the effect of suspended solids on the oxidation and hydrolysis of the insecticide endosulfan (α and β isomers) and its degradation products:  endosulfan diol, endosulfan sulfate, endosulfan ether, and endosulfan lactone in 0.001 M NaHCO3 buffer (pH 8.15). Suspensions of sea sand, TiO2, α-Fe2O3, α-FeOOH, Laponite, and SiO2 all catalyzed the hydrolysis of endosulfan to the less toxic endosulfan diol. Suspended creek sediment (Bread and Butter Creek SC, 4% OC) inhibited endosulfan hydrolysis. Heterogeneous and homogeneous rate constants of endosulfan hydrolysis were measured and indicate that β-endosulfan hydrolyzes faster than α-endosulfan. This observation was explained by a more stable transition state for β-endosulfan that was confirmed with ab initio molecular orbital calculations (STO-6G) on the anionic intermediates of endosulfan hydrolysis. Rates of endosulfan hydrolysis over the different surfaces corresponded to their tritium-exchange site-density and suggest a mechanism involving surface coordination prior to nucleophilic attack. The oxidation of α-endosulfan and β-endosulfan to the persistent pollutant endosulfan sulfate was not observed in this study

Votes of Preference.

<p>Total number of eggs deposited in host A = 24, 12, 20, and 18; host <b>B</b>, 21, 21, 18, 17; and host <b>C</b>, 23, 20, 19, and 16.</p><p>“Votes of preference” for a hypothetical multiple-choice study involving four host selection behavior trials of individual females when concurrently exposed to three hosts.</p