Impact of Simulated California Rice-Growing Conditions on Chlorantraniliprole Partitioning

Chlorantraniliprole (3-bromo-<i>N</i>-[4-chloro-2-methyl-6-(methylcarbamoyl)­phenyl]-1-(3-chloro-2-pyridine-2-yl)-1<i>H</i>-pyrazole-5-carboxamide, CAP; water solubility 1.023 mg·L^–1) was recently registered for application on California rice fields. Air– and soil–water partitioning of CAP were investigated under simulated California rice field conditions through calculation of <i>K</i>_H and Δ_aw<i>H</i> and a batch equilibrium method following OECD 106 guidelines, respectively. <i>K</i>_H and Δ_aw<i>H</i> were determined to be 1.69 × 10^–16 – 2.81 × 10^–15 atm·m³·mol^–1 (15–35 °C) and 103.68 kJ·mol^–1, respectively. Log­(<i>K</i>_oc) ranged from 2.59 to 2.96 across all soil and temperature treatments. Log­(<i>K</i>_<i>F</i>) ranged from 0.61 to 1.14 across all soil, temperature, and salinity treatments. Temperature and salinity increased sorption significantly at 35 °C (<i>P</i> < 0.05) and 0.2 M (<i>P</i> < 0.0001), respectively, while soil properties impacted sorption across all treatments. Overall results, corroborated using the Pesticides in Flooded Applications Model, indicate that volatilization of CAP is not a major route of dissipation and sorption of CAP to California rice field soils is moderately weak and reversible

Reactive Oxygen Species and Chromophoric Dissolved Organic Matter Drive the Aquatic Photochemical Pathways and Photoproducts of 6PPD-quinone under Simulated High-Latitude Conditions

The photochemical degradation pathways of 6PPD-quinone (6PPDQ, 6PPD-Q), a toxic transformation product of the tire antiozonant 6PPD, were determined under simulated sunlight conditions typical of high-latitude surface waters. Direct photochemical degradation resulted in 6PPDQ half-lives ranging from 17.5 h at 20 °C to no observable degradation over 48 h at 4 °C. Sensitization of excited triplet-state pathways using Cs+ and Ar purging demonstrated that 6PPDQ does not decompose significantly from a triplet state relative to a singlet state. However, assessment of processes involving reactive oxygen species (ROS) quenchers and sensitizers indicated that singlet oxygen and hydroxyl radical do significantly contribute to the degradation of 6PPDQ. Investigation of these processes in natural lake waters indicated no difference in attenuation rates for direct photochemical processes at 20 °C. This suggests that direct photochemical degradation will dominate in warm waters, while indirect photochemical pathways will dominate in cold waters, involving ROS mediated by chromophoric dissolved organic matter (CDOM). Overall, the aquatic photodegradation rate of 6PPDQ will be strongly influenced by the compounding effects of environmental factors such as light screening and temperature on both direct and indirect photochemical processes. Transformation products were identified via UHPLC-Orbitrap mass spectrometry, revealing four major processes: (1) oxidation and cleavage of the quinone ring in the presence of ROS, (2) dealkylation, (3) rearrangement, and (4) deamination. These data indicate that 6PPDQ can photodegrade in cool, sunlit waters under the appropriate conditions: t1/2 = 17.4 h tono observable decrease (direct); t1/2 = 5.2-11.2 h (indirect, CDOM)

A light touch: solar photocatalysis detoxifies oil sands process-affected waters prior to significant treatment of naphthenic acids or acid extractable organics

The toxicity of oil sands process-affected water (OSPW) has been associated to its dissolved organics, a complex mixture of naphthenic acid fraction components (NAFCs). Here, we evaluated solar treatment with buoyant photocatalysts (BPCs) as a candidate passive advanced oxidation process (P-AOP) for OSPW remediation, according to both analytical chemistry and standard rainbow trout (Oncorhynchus mykiss) and fathead minnow (Pimephales promelas) whole effluent toxicity (WET) bioassays. Solar photocatalysis with BPCs fully degraded naphthenic acids (NAs) and acid extractable organics (AEO) in 3 different OSPW samples, however fish toxicity was eliminated well before concentrations of dissolved organics had significantly diminished, within <2 days of sunlight exposure for all OSPWs. Classical NAs and AEO, traditionally considered among the principal toxicants in OSPW, were not correlated with OSPW toxicity herein. Instead, petroleomic mass spectrometry (MS) analysis revealed low polarity organosulfur NAFCs – O2S− and OS+ (putatively naphthenic sulfoxides), together composing <10% of the total AEO – were correlated with WET outcomes, and apparently accounted for the majority of waters’ toxicity, as described by a physiologically-based model (PBM) of tissue partitioning. These results demonstrate that complete elimination of OSPW toxicity per standard WET bioassays is achievable without significant changes to overall concentrations of dissolved organics, suggesting that most AEO are toxicologically benign, and toxicity may instead be driven by only a small subset of NAFCs, which are preferentially photocatalytically treated. These findings have implications for OSPW release, for which a less extensive but more selective treatment may be required than previously expected

Absolute and Relative Vaccine Effectiveness of Primary and Booster Series of COVID-19 Vaccines (mRNA and Adenovirus Vector) Against COVID-19 Hospitalizations in the United States, December 2021–April 2022

BackgroundCoronavirus disease 2019 (COVID-19) vaccine effectiveness (VE) studies are increasingly reporting relative VE (rVE) comparing a primary series plus booster doses with a primary series only. Interpretation of rVE differs from traditional studies measuring absolute VE (aVE) of a vaccine regimen against an unvaccinated referent group. We estimated aVE and rVE against COVID-19 hospitalization in primary-series plus first-booster recipients of COVID-19 vaccines.MethodsBooster-eligible immunocompetent adults hospitalized at 21 medical centers in the United States during December 25, 2021-April 4, 2022 were included. In a test-negative design, logistic regression with case status as the outcome and completion of primary vaccine series or primary series plus 1 booster dose as the predictors, adjusted for potential confounders, were used to estimate aVE and rVE.ResultsA total of 2060 patients were analyzed, including 1104 COVID-19 cases and 956 controls. Relative VE against COVID-19 hospitalization in boosted mRNA vaccine recipients versus primary series only was 66% (95% confidence interval [CI], 55%-74%); aVE was 81% (95% CI, 75%-86%) for boosted versus 46% (95% CI, 30%-58%) for primary. For boosted Janssen vaccine recipients versus primary series, rVE was 49% (95% CI, -9% to 76%); aVE was 62% (95% CI, 33%-79%) for boosted versus 36% (95% CI, -4% to 60%) for primary.ConclusionsVaccine booster doses increased protection against COVID-19 hospitalization compared with a primary series. Comparing rVE measures across studies can lead to flawed interpretations of the added value of a new vaccination regimen, whereas difference in aVE, when available, may be a more useful metric