Matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) and liquid extraction surface analysis (LESA) with nanoelectrospray ionization mass spectrometry (nESI-MS) have both been successfully employed to determine the degree of percutaneous absorption of three novel nonsteroid glucocorticoid receptor (GR) agonists in porcine ear sections. Historically, the ability of a glucocorticoid to elicit a skin blanching response when applied at low dose in ethanol solution to the forearms of healthy human volunteers has been a reliable predictor of their topical anti-inflammatory activity. While all three nonsteroidal GR agonists under investigation caused a skin blanching effect, the responses did not correlate with in vitro GR agonist potencies and different time courses were also observed for the skin blanching responses. MALDI MSI and LESA with nESI-MS were used to investigate and understand these different responses. The findings of the investigation was that the depth of porcine skin penetration correlates to the degree of skin blanching obtained for the same three compounds in human volunteers.

Abstract:The authors performed a multiple-pulsed atrazine experiment to measure responses of autotrophic endpoints in outdoor stream mesocosms. The experiment was designed to synthetically simulate worst-case atrazine chemographs from streams in agricultural catchments to achieve 60-d mean concentrations of 0 mg/L (control), 10 mg/L, 20 mg/L, and 30 mg/L. The authors dosed triplicate streams with pulses of 0 mg/L, 50 mg/L, 100 mg/L, and 150 mg/L atrazine for 4 d, followed by 7 d without dosing. This 11-d cycle occurred 3 times, followed by a recovery (untreated) period from day 34 to day 60. Mean AE standard error 60-d atrazine concentrations were 0.07 AE 0.03 mg/L, 10.7 AE 0.05 mg/L, 20.9 AE 0.24 mg/L, and 31.0 AE 0.17 mg/L for the control, 10-mg/L, 20-mg/L, and 30-mg/L treatments, respectively. Multivariate analyses revealed that periphyton and phytoplankton community structure did not differ among treatments on any day of the experiment, including during the atrazine pulses. Control periphyton biomass in riffles was higher immediately following the peak of the first atrazine pulse and remained slightly higher than some of the atrazine treatments on most days through the peak of the last pulse. However, periphyton biomass was not different among treatments at the end of the present study. Phytoplankton biomass was not affected by atrazine. Metaphyton biomass in pools was higher in the controls near the midpoint of the present study and remained higher on most days for the remainder of the study. Ceratophyllum demersum, a submersed macrophyte, biomass was higher in controls than in 20-mg/L and 30-mg/L treatments before pulse 3 but was not different subsequent to pulse 3 through the end of the present study. Maximum daily dissolved oxygen (DO, percentage of saturation) declined during each pulse in approximate proportion to magnitude of dose but rapidly converged among treatments after the third pulse. However, DO increased in controls relative to all atrazine treatments during the last 17 d of the experiment, likely a result of metaphyton cover in the pools. Finally, atrazine significantly limited uptake of PO 4 3-and uptake and/or denitrification of NO 3 -but only during pulses; percentage of dose removed from the water column was >85% for P and >95% for N after pulse 3 through the end of the present study. Collectively, only DO and metaphyton biomass differed at the end of the present study and only slightly. Some other endpoints were affected but only during pulses, if at all. The high levels of primary production and accumulation of algal biomass in all streams suggest that effects of pulses of atrazine at the concentrations used in the present study appear transient and likely do not represent ecologically significant adverse outcomes to periphyton, phytoplankton, and aquatic macrophytes, particularly in agricultural streams subjected to high nutrient loads. Environ Toxicol Chem 2016;35:660-675. #

The effects of changing hydrodynamic conditions and changing temperatures on polar organic chemical integrative sampler (POCIS) sampling rates (R ) were investigated for 12 crop protection chemicals. Exposure concentration was held constant in each laboratory experiment, and flow velocities were calculated from measured mass transfer coefficients of the water boundary layer near the surface of POCIS devices. At a given temperature R generally increased by a factor of 2 to 5 between a stagnant condition and higher flow velocities (6-21 cm/s), but R for most compounds was essentially constant between the higher flow velocities. When temperature was varied between 8 and 39 °C for a given flow condition, R increased linearly. In general, R increased by a factor of 2 to 4 and 2 to 8 over this temperature range under flow and stagnant conditions, respectively. An Arrhenius model was used to describe the dependence of POCIS sampling rates on temperature. Adjustments of R for temperature did not fully explain observed differences between time-weighted average concentrations of atrazine determined from POCIS and from composite water sampling in a field setting, suggesting that the effects of other competing factors still need to be evaluated. Environ Toxicol Chem 2018;37:2331-2339. © 2018 SETAC.

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Polar organic chemical integrative sampler (POCIS) is a passive sampling device that offers many advantages over traditional discrete sampling methods, but quantitative timeweighted average (TWA) concentrations rely heavily on the robustness of sampling rates. The effects of changing chemical concentration exposures on POCIS sampling rates and its ability to operate in an integrative regime were investigated for 12 pesticides across a range of environmentally relevant concentrations. In five independent 21-day experiments, POCIS devices were exposed to these compounds at constant concentrations ranging from 3 to 60 μg/L and multiple pulsed concentrations with maximum peaks ranging from 5 to 150 μg/L (TWA concentrations = 3 to 92 μg/ L). For the 21-day exposures to constant and pulsed concentrations, there were no significant differences in the POCIS sampling rates between corresponding TWA concentrations. Similarly, there was no significant effect on POCIS ability to operate in an integrative regime. However, loss of linearity was visible for some replicates when exposed to higher pulsed concentrations over an extended period. Modeling and Freundlich isotherms did not predict sorbent saturation, but the extraction and reconstitution protocol likely contributed to atrazine dissolution and subsequent underestimation of sorbed chemical mass when HLB adsorption exceeded 400 μg.