Developing Global Leaders for Research, Regulation, and Stewardship of Crop Protection Chemistry in the 21st Century

To provide sufficient food and fiber to the increasing global population, the technologies associated with crop protection are growing ever more sophisticated but, at the same time, societal expectations for the safe use of crop protection chemistry tools are also increasing. The goal of this perspective is to highlight the key issues that face future leaders in crop protection, based on presentations made during a symposium titled “Developing Global Leaders for Research, Regulation and Stewardship of Crop Protection Chemistry in the 21st Century”, held in conjunction with the IUPAC 13th International Congress of Pesticide Chemistry in San Francisco, CA, USA, during August 2014. The presentations highlighted the fact that leaders in crop protection must have a good basic scientific training and understand new and evolving technologies, are aware of the needs of both developed and developing countries, and have good communication skills. Concern is expressed over the apparent lack of resources to meet these needs, and ideas are put forward to remedy these deficiencies.Keywords: sustainable agriculture, developing regions, training leaders, smart systems, stewardship, women in agriculture, crop protection, universities, nanopesticides, communications, GM crop

Effects of Faujasite X and Y Zeolites on the 1,1,1-Trichloro-2,2? bis(p-chlorophenyl)ethane (DDT) Degradation during Water Purification

The ability of zeolites to abstract and denature organochloride pesticides finds application in water purification practices. In this study, activated faujasite X and Y zeolites were separately exposed to 1, 2 and 4 ppm concentrations of 1,1,1-trichloro-2,2’ bis(p-chlorophenyl) ethane (dichloro dipheny trichloroethane - DDT) water solutions. For the 1 ppm DDT solutions, the resultant degradation products and residual DDT were minimal with concentrations in zeolite treatments reducing to below detection limit (0.005 ppm) in about 2 hours. In addition, the rate of dissipation was found to somewhat depend on the levels of DDT concentration and the type of zeolite used. The main degradation product in samples exposed to faujasite X was dichloro dipheny dichloroethylene (DDE) whereas in the faujasite Y exposed samples, both the DDE and dichloro diphenyl dichloroethane (DDD) were obtained

Effects of Zeolite X on Dissipation of Hexazinone from Agricultural Waste Waters in Western Kenya

Dissipation of hexazinone in Zeolite X treated wastewater followed pseudo first-order kinetics giving a calculated half-life of 41 days compared to a half-life of 144 days in untreated wastewater. The herbicide degraded faster (0.0067 h-1 ) in treated than in nonzeolite-treated wastewater (0.0027 h-1 ) forming products A, B, C, D and E within the first 12 h. Zeolite X effectively catalyzed the formation of product A compared to the rest. Calculated rate constants for formation of products A, B, D and E were: 8.33 x 10-4 h -1 , 5.65 x 10-4 h -1 , 5.52 x 10-4 h -1 and 1.38 x10-3 h -1 respectively in non-zeolite-treated wastewater; and 3.988 x 10-3 h -1 , 4.875 x 10-4 h -1 , 4.745 x 10-4 h -1 and 2.82 x 10-3 h -1 respectively in zeolite-treated wastewater

Effects of zeolites X and Y on the degradation of malathion in water

The inclusion of both zeolites X and zeolite Y significantly affected the dissipation of malathion in water. In the fresh water, malathion degradation followed a pseudo-first order kinetics with concomitant half-life dropping from 8.76 hours in fresh water to 4.44 and 6.65 hours up on the introduction of faujasite X and Y, respectively. Zeolite X had higher degradation efficiency as compared to the Y type. In pure fresh water, Malathion mainly hydrolyzed to form malathion monocarboxylic and dicarboxylic acids as the only degradation products. However, in the presence of zeolites X and Y, in addition to the degradation products obtained in the fresh water, dimethyldithiophosphate was also formed. Notably, all the degradation products obtained are environmentally benign compared to the parent malathion. Eventually, both the adsorption on the zeolite framework and zeolite catalyzed degradation processes contributed to the overall dissipation behavior of the malathion and its degradation products

Synthesis of ring-14C-labelled 4(3'-,6'-dimethyl-3'-heptyl1)-phenol

Ring-C-14-labelled 4(3'-, 6'-, dimethyl-3'-,heptyl)-phenol (NP), an isomer of paranonyl phenol was synthesized for use in aquatic toxicity and metabolism studies. A very efficient method involving alkylation of ring-C-14-labeled anisole and tertiary alkyl bromide (3-bromo-3,6-dimethyl heptane) with AlCl3 followed by cleavage of the resultant ether with BBr3 was used giving a 24% yield ring labelled C-14-NP (specific activity: 16.205 MBq/mg and purity > 95% by HPLC) after TLC separation

Effects of a Branched p-Nonylphenol Isomer (4(3',6'-dimethyl-3'-heptyl)-phenol) on Embryogenesis in Lymnae stagnalis L.

The tertiary branched alkyl-chain isomers of p-nonylphenol (NP) are perceived to have more estrogenic potency than its constituent secondary and primary straight alkyl-chain isomers. Investigations with single tertiary branched isomers of NP can therefore contribute toward the elucidation of the mechanisms of toxicity and estrogenicity of NP. A single tertiary branched alkyl-chain isomer (4(3',6'-dimethyl-3'-heptyl)-phenol) was used in studies to determine its effects on embryonic growth and mortality in Lymnaea stagnalis L. Egg masses were exposed to the test compound for 20 days in a static waterborne-exposure regime with an average NP concentration of 105 microg/L and water temperature range of 18-20 degrees C. Observations were made under a microscope and pictures were taken with a digital camera to determine the various developmental stages of growth, the duration of growth in each stage, embryo hatchability, and embryo mortality. The isomer was found to cause significant delay in all stages of growth and more significantly in the Morula and Veliger stages. An increase in embryo mortality, from the third day until the end of the experiment, was observed in exposed egg masses compared to controls. The hatching success of embryos was also significantly reduced by exposure, with 81% hatchability in exposed egg masses compared to 93% in the controls, after 18 days of continuous exposure. The encapsulating jelly strand that completely covers the rows of egg masses may have prevented the isomer residues from effectively penetrating into the embryos as shown by the observed low bioconcentration factors of the isomer in egg masses during exposure, resulting in unexpectedly lower observed estrogenic effects. However, this factor was not investigated. In vivo biotransformation of some of the residues of the isomer into catechol metabolites by the embryos during exposure could also result in the reduction of its estrogenic potential. To understand more fully the extent of toxicity and estrogenicity of this isomer, in vitro estrogenic assays are recommended. It would also be necessary to investigate its estrogenic effects on embryo development after in vivo maternal exposure

In vivo metabolism and organ distribution of a branched 14C-nonylphenol isomer in pond snails, Lymnaea stagnalis L.

The branched isomers of p-nonylphenol (NP) are perceived to be more resistant to biodegradation in aquatic environments as well as to have more estrogen-like toxicity than the straight chain isomers. By use of GC-MS, some of them have been identified and found to exist in higher concentrations in the isomeric compound mixture than the straight chain isomers. The investigations of the distribution and metabolism of these branched isomers in aquatic organisms are therefore considered to be important in understanding the mechanisms of toxicity of NP. A single tertiary isomer of NP, 4(3'-,6'-dimethyl-3'-heptyl)-phenol, was synthesized in the laboratory and used in in vivo studies of its organ distribution and metabolism in Lymnaea stagnalis L., following a constant exposure of the organisms to C-14-NP isomer in water over a period of 8 days at an average exposure concentration of 105 ppb (range: 93-116 ppb). The results obtained clearly showed the distribution and bioconcentration of the isomer residues in various internal organs of Lymnaea after uptake in water and food. Analysis of the extracts of the organ tissues and faeces by HPLC and GC- MS after digestion with Pankreatin/beta-glucuronidase and nitric acid, respectively, showed that the isomer was metabolized by conjugation to glucuronic acid and hydroxylation to a catechol. The findings from these studies and their implications in the biotransformation and estrogenicity of NP in Lymnaea stagnalis L. are further discussed in detail in this paper. (C) 2002 Elsevier Science B.V. All rights reserved