Analysis of pesticide runoff from mid-Texas estuaries and risk assessment implications for marine phytoplankton

During 1993, estuarine surface water samples were collected from the mid-Texas coast (Corpus Christi to Port Lavaca, TX). Agricultural watershed areas as well as tidal creeks immediately downstream were chosen as sampling sites along with adjoining bay sampling stations. Collections were made throughout the growing season (February to October 1993) before and after periods of significant (> 1.25 cm) rainfall. All samples were initially screened for the presence of pesticides using enzyme-linked immunosorbent assay (ELISA) test kits (EnviroGard) for triazine herbicides and carbamate insecticides. All samples were extracted and then analyzed using gas chromatography (GC) for quantification of atrazine. Only samples testing positive for carbamate insecticides via ELISA were further extracted for GC analysis to quantify aldicarb and carbofuran. Additionally, laboratory toxicity tests using phytoplankton were examined from published, peer-reviewed literature and compared with the atrazine field levels found in Texas. Results of ELISA screening indicated the presence of triazine herbicides in nearly all samples (>93%). GC analysis further confirmed the presence of atrazine concentrations ranging from <0.01-62.5 microg/L. Screening tests also found detectable levels of carbamate insecticides (aldicarb and carbofuran) that were also confirmed and quantified by GC. Comparison of measured concentrations of atrazine compared with published toxicity tests results indicated that there was a potential environmental risk for marine/estuarine phytoplankton in surface waters of Texas estuaries, particularly when the chronic nature of atrazine exposure is considered.     

Static magnetic field therapy: methodological challenges to conducting clinical trials

Static magnetic field (SMF) therapy delivered by permanent magnets is being used as a self-care intervention by millions of people worldwide, despite a paucity of clinical research confirming or refuting therapeutic effectiveness. Evaluating the reported results of SMF clinical trials is difficult because researchers use heterogeneous dosing regimens, unreliable sham controls, and questionable blinding strategies. Three important methodological challenges need to be contended with when conducting and interpreting SMF studies: optimization of SMF dosimetry, use of a believable physiologically inert sham, and assurance of participant blinding in unsupervised settings. Our objectives in writing this review are to describe ten essential SMF dosing parameters that need to be reported in SMF clinical trials and to discuss sham controls and blinding procedures for SMF studies.