Predictions of tissue concentrations of myclobutanil, oxyfluorfen, and pronamide in rat and human after oral exposures via GastroPlusTM physiologically based pharmacokinetic modelling.

Heritage agrochemicals like myclobutanil, oxyfluorfen, and pronamide, are extensively used in agriculture, with well-established studies on their animal toxicity. Yet, human toxicity assessment relies on conventional human risk assessment approaches including the utilization of animal-based ADME (Absorption, Distribution, Metabolism, and Excretion) data. In recent years, Physiologically Based Pharmacokinetic (PBPK) modelling approaches have played an increasing role in human risk assessment of many chemicals including agrochemicals. This study addresses the absence of PBPK-type data for myclobutanil, oxyfluorfen, and pronamide by generating in vitro data for key input PBPK parameters (Caco-2 permeability, rat plasma binding, rat blood to plasma ratio, and rat liver microsomal half-life), followed by generation of PBPK models for these three chemicals via the GastroPlusTM software. Incorporating these experimental input parameters into PBPK models, the prediction accuracy of plasma AUC (area under curve) was significantly improved. Validation against rat oral administration data demonstrated substantial enhancement. Steady-state plasma concentrations (Css) of pronamide aligned well with published data using measured PBPK parameters. Following validation, parent-based tissue concentrations for these agrochemicals were predicted in humans and rats after single or 30-day repeat exposure of 10 mg/kg/day. These predicted concentrations contribute valuable information for future human toxicity risk assessments of these agrochemicals.

Performance evaluation of the GastroPlusTM software tool for prediction of the toxicokinetic parameters of chemicals.

The accurate prediction of toxicokinetic parameters arising from oral, dermal and inhalation routes of chemical exposure is a key element in chemical safety assessments. In this research, the physiologically based pharmacokinetic (PBPK) GastroPlusTM software was evaluated against a series of chemicals for the prediction of toxicokinetic parameters. Overall, 67% of predicted intrinsic clearance (Clint) values were within 1- to 10-fold of empirical data for 463 compounds, and 87% of the predicted fraction unbounded in plasma (Fup) values were 1- to 3-fold of empirical data for 441 compounds. The r2 (coefficient of determination) of predicted Cmax (maximum plasma concentration) and AUC (Area Under Curve) values versus the corresponding empirical values from oral, inhalation and dermal exposures ranged from 0.04 to 0.92. Among the three exposures, the highest r2 values, ranging from 0.80 to 0.92, were observed for oral exposure predictions, where 88% of the compounds had 1- to 10-fold differences between predicted and empirical values for Cmax and AUC. The predicted plasma Css (steady-state plasma concentration) values were consistent with those Css values calculated by in vitro-to-in vivo extrapolation (IVIVE) approaches using experimental parameters. Based on the evaluation results, GastroPlus™ can be used as a QSAR/PBPK tool for toxicokinetic parameter predictions.

Farm injuries in Ohio, 2003-2006: a report from the emergency medical services prehospital database.

Agriculture has among the highest numbers and rates of fatal and nonfatal traumatic injuries in the U.S. Surveillance is an integral part of injury prevention. However, traditional sources of surveillance data are incomplete and inaccurate in describing agricultural injuries. The goals of this research are to describe acute, traumatic farm injuries in Ohio utilizing the Ohio EMS prehospital (ambulance run) database, and to explore the database's utility in agricultural injury surveillance. Ohio mandates reporting of responses to every call for emergency medical services (EMS) in the state. A dataset containing every transported injury case from 2003-2006 was obtained A descriptive analysis of farm injuries was conducted and compared to existing surveillance sources. Of the total transported injuries, 15% (1714 injured individuals) came from farms. "Falls" were the most common cause of injury in all age groups except ages 15-24, in which "off-road vehicles" were most common. Other leading causes include "ridden animal", "machinery", and "caused by animal". These results are similar to other data sources. Strengths of EMS databases include mandatory reporting, low expense, and lack of need for employer or worker reporting. They may be used to look at injury severity, quality of acute care, resource allocation, and to assess the need for specialized training of EMS personnel. Limitations are lack of specificity for work-related agricultural injuries and variation in definitions of data elements. EMS prehospital databases are an important source of data for agricultural injury surveillance.

Effects of rutin-fed caterpillars on an invertebrate predator depend on temperature.

A factorial experiment examined the effects of varying concentrations of the allelochemical rutin in caterpillars and the length of time the caterpillars had fed on the behavioral interactions of predatory stinkbugs (Podisus maculiventris) and their prey (Manduca sexta). Diet had no significant effect on defensive behavior of the caterpillars. The length of time that the caterpillars had fed (1 vs. 24 h) only influenced the frequency of caterpillars knocking the attacking stinkbugs away, with caterpillars knocking the stinkbugs away more often after 24 h of feeding. A second experiment tested the effects of diet (prey fed various concentrations of rutin), temperature (18° C and 28° C) and gender on consumption and growth parameters of fifth instar stinkbugs. At the cooler temperature, the bugs ate more, gained more weight but took twice as long to complete the stadium and consequently had reduced relative consumption and relative growth rates. Diet had no significant effect on biomass gained or stadium duration, but rutin-fed caterpillars did depress the stinkbugs' relative consumption rates. The effect of food quality on relative growth rate (RGR) was temperature dependent; rutin had no significant effect at the cooler temperature, but a high dose of rutin reduced RGR at the warmer temperature. Rutin had a greater negative impact on the females than the males. The effect of rutin on these predators was different than the effect on their prey (this study compared to Stamp (1990, 1992)): the negative effects of rutin seem to impact on the stinkbug's growth rather than on molting.