Pesticides future studies

Future studies must focus on those specific agricultural technologies that have contributed to the increased use of pesticides during the past 40 years, and why crop losses to pests continue to Increase. Research needs not only to identify the detrimental technologies, but, more Important, develop ecologically sound practices that farmers can use as profitable substitutes (15). 

Much of the literature on the use of plant cell cultures in pesticide research concerns herbicide metabolism and it will be emphasized here. However the comparative metsbolism of other classes of pesticides in plants and plant cell cultures will also be reviewed. The advantages and disadvantages of plant cell cultures in pesticide metabolism studies will be presented and a prognosis of the future attempted. 

What does the future hold Can pesticide metabolism studies and the data they generate be more effectively used in the safety evaluation process Can these studies be made more predictive and thus more toxicologic ally relevant to man It is, of course, difficult if not impossible to foresee the future accurately. We will, however, make a few observations on these and other matters. 

Mata-Sandoval et al. [32] compared the ability of the rhamnolipid mixture to solubilize the pesticides, trifluralin, coumaphos and atrazine, with the synthetic surfactant Triton X-100. The synthetic surfactant was able to solubihze approximately twice as much of all pesticides as the rhamnolipid. The biosurfactant seems to bind trifluralin tightly in the micelle and releases the pesticide slowly to the aqueous phase, which could have implications for microbial uptake. This approach utilizing micellar solubilization capacities and aqueous-miceUe solubilization rate coefficients and micellar-aqueous transfer rate coefficients could be useful for future studies on microbial uptake. Addition of rhamnohpid in the presence of cadmium enabled biodegradation of the hydrocarbon naphthalene to occur as if no cadmium was present [33]. 

The need to develop and use chiral chromatographic techniques to resolve racemates in pesticide residues will be driven by new hazard and risk assessments undertaken using data from differential metabolism studies. The molecular structures of many pesticides incorporate chiral centers and, in some cases, the activity differs between enantiomers. Consequently, in recent years manufacturers have introduced resolved enantiomers to provide pesticides of higher activity per unit mass applied. For example, the fungicide metalaxyl is a racemic mix of R- and 5-enantiomers, both having the same mode of action but differing considerably in effectiveness. The -enantiomer is the most effective and is marketed as a separate product metalaxyl-M. In future, it will not be satisfactory to rely on hazard/risk assessments based on data from metabolism studies of racemic mixes. The metabolism studies will need to be undertaken on one, or more, of the resolved enantiomers. 

The scientific community is indebted to Alexey Yablokov and Lev Fedorov for carefully examining the pesticide impact on public health and the environment. Their studies add to our knowledge and their results suggest ways that public health and environmental pesticide related problems could be avoided. Given the food security needs of the rapidly expanding world human population, a safe and a productive agriculture are vital for the future. 

A majority of U.S. biomonitoring efforts measure such analytes as heavy metals, pesticides, cotinine, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polychlorinated dibenzodioxins, phthalates, and volatile organic compounds (VOCs). Future population-based studies (such as NHANES) will include such chemicals as perfluorinated compounds, polybrominated diphenyl ethers (PBDEs), and perchlorate, on which little exposure information is available. 

It is desirable to collect as many different matrices from each study participant as is feasible and to process them with consideration of both immediately planned analyses of biomarkers and future uses. For example, several Children s Environmental Health Centers obtained urine, peripheral blood, cord blood, breast milk, meconium, saliva, hair, placental tissue, infant formula, indoor and outdoor air, and house dust from longitudinal birth cohort studies (Eskenazi et al. 2005). The centers have analyzed concentrations of numerous compounds in those biologic and environmental samples, such as pesticides, phthalates, mercury, lead, cotinine, polycyclic aromatic hydrocarbone (PAHs), PAH-DNA adducts, allergens, endotoxin, antioxidant micronutrients, cholinesterase, and thyroid hormones. Most centers also banked samples for future analyses. 

Although the predominant source of arsenic and metals to most soils and sediments in New England is sulfide-rich rock, the extensive application of arsenical pesticides and herbicides (lead arsenate, calcium arsenate, and sodium arsenate, and others) on apple, blueberry, and potato fields may have been a possible anthropogenic source of arsenic and lead. The main objective of this study was to determine the lead isotopic compositions of commonly used pesticides, such as lead arsenate, sodium metarsenite, and calcium arsenate, in order to assist in future isotopic comparisons and to better characterize this anthropogenic source of Pb. The pesticides plot along a linear trend in isotope diagrams, for example, in values of... 

Swan SH, Kruse RL, Liu F, Barr DB, Drobnis EZ, Redmon JB, Wang C, Brazil C, Overstreet JW, the Study for Future Families Research Group. 2003. Semen quality in relation to biomarkers of pesticide exposure. Environ Health Perspect 111 1478-1484. 

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