Betaine and Carnitine Derivatives as Herbicidal Ionic Liquids.

This study focused on the synthesis and subsequent characterization of herbicidal ionic liquids based on betaine and carnitine, two derivatives of amino acids, which were used as cations. Four commonly used herbicides (2,4-D, MCPA, MCPP and Dicamba) were used as anions in simple (single anion) and oligomeric (two anions) salts. The obtained salts were subjected to analyzes regarding physicochemical properties (density, viscosity, refractive index, thermal decomposition profiles and solubility) as well as evaluation of their herbicidal activity under greenhouse and field conditions, toxicity towards rats and biodegradability. The obtained results suggest that the synthesized herbicidal ionic liquids displayed low toxicity (classified as category 4 compounds) and showed similar or improved efficacy against weed compared to reference herbicides. The highest increase was observed during field trials for salts containing 2,4-D as the anion, which also exhibited the highest biodegradability (>75 %).

The influence of low concentration of cypermethrin and deltamethrin on phyto- and zooplankton of surface waters.

Pyrethroids play an important role in modern agriculture but their use is not without risks to non-target organisms and habitats. They have high toxicity to a broad spectrum of aquatic organisms. The aim of the study was to investigate the effect of low concentration (0.02 µg l(-1)) of two widely used pyrethroids--cypermethrin and deltamethrin on phyto- and zooplankton. The acute bioassays were conducted using Chlorella vulgaris and Thamnocephalus platyurus. Then, the chronic bioassays were conducted using Chlorella vulgaris, Daphnia magna and Brachionus calycilforus. The 24h LC50 values for cypermethrin and deltamethrin to Thamnocephalus platyurus were 0.89 µg l(-1) and 1.51 µg l(-1), respectively. The 48h EC50 values for cypermethrin and deltamethrin to Brachionus calycilforus were 3.828 mg l(-1) and 8.425 mg l(-1), respectively. 13% growth inhibition of Chlorella vulgaris (statistically insignificant) after 14 days of exposure to deltamethrin as well as cypermethrin was observed.

OECD validation study to assess intra- and inter-laboratory reproducibility of the zebrafish embryo toxicity test for acute aquatic toxicity testing.

The OECD validation study of the zebrafish embryo acute toxicity test (ZFET) for acute aquatic toxicity testing evaluated the ZFET reproducibility by testing 20 chemicals at 5 different concentrations in 3 independent runs in at least 3 laboratories. Stock solutions and test concentrations were analytically confirmed for 11 chemicals. Newly fertilised zebrafish eggs (20/concentration and control) were exposed for 96h to chemicals. Four apical endpoints were recorded daily as indicators of acute lethality: coagulation of the embryo, lack of somite formation, non-detachment of the tail bud from the yolk sac and lack of heartbeat. Results (LC50 values for 48/96h exposure) show that the ZFET is a robust method with a good intra- and inter-laboratory reproducibility (CV<30%) for most chemicals and laboratories. The reproducibility was lower (CV>30%) for some very toxic or volatile chemicals, and chemicals tested close to their limit of solubility. The ZFET is now available as OECD Test Guideline 236. Considering the high predictive capacity of the ZFET demonstrated by Belanger et al. (2013) in their retrospective analysis of acute fish toxicity and fish embryo acute toxicity data, the ZFET is ready to be considered for acute fish toxicity for regulatory purposes.