Research of highly specific end metabolic product biomarkers to pesticide contamination:
Example of an approach from field to plate in food production lines
In humans, exposure to pesticides is mainly due to feeding. Controlling and limiting pesticide ingestion thus represents major healthy challenges in the next decades. Because the direct control of pesticide residues in environment is difficult, one prominent solution to preserve human and animal health is to offer alternative tools allowing larger and routine monitoring of pesticide exposure along a continuum of food production (i.e. from field to plate). Indeed, to date, agencies for sanitary safety and environmental surveys use efficient but very costly and hazardous methods measuring pesticide residues and their metabolites in a restrictive subset of food samples.
Alternative tools we propose consist on the search and quantification of highly specific metabolic biomarkers (i.e. organic volatile compounds) generated by exposure to a pesticide (or one pesticide family). Since the past decade, research in cancerology highlighted the increasing interest of organic volatile compounds as highly specific biomarkers to detect lung cancers and its distinct maturity stages in humans (Hakim et al, 2011 for a review). Following this dynamic and eco-toxicogenomic theories, we suggest that exposure to different pesticides in biological matrices should generate specific metabolic responses (i.e. pathways directly induce by pesticides + response/detoxification pathways counteracting physiological damages induce by the previous ones), which in their turn should specifically modulate the organic volatile compounds. Recent works conducted during the European SigmaChain project approved the metabolic biomarker role of the organic volatile compounds, notably in the liver of poultries exposed to pesticides during juvenile development (Berge et al., 2012). This work was then comforted by the current PhD of J. Bouhlel conducted in our team.
Accordingly, we compare the volatolome of distinct species which were chosen to represent a continuum of food production from field to plate according they were exposed to a pesticide (deltamethrine) or not (control group). Species we are studying in this project are: micro-organisms (Bacillus megaterium, Pseudomonas sp, and Paramecium sp) which are good sanitary bio-indicators of soil and water in fields; the honey bee (Apis mellifera) which is a sentinel of the environment and the chicken and zebrafish which represent tissue intended for food and thus contaminate the final consumer. The use of rats is envisaged to represent the final consumer and to help us to better understand how pesticides are transfer. Choice of species is based on local expertise and the ease to rear and exposed specimens to the pesticide. For each species, we adapt and optimize the extraction and the concentration of organic volatile compounds using the headspace SPME technique developed by Pawliszyn in 1990 (Theodoridis, Koster, and de Jong 2000; Xu et al. 2016 for examples). Separation, identification and quantification of compounds are realized using a GC-MS.
References
Berge P, Ratel J, Fournier A, Jondreville C, Feidt C, Roudaut B, et al. Use of volatile compound metabolic signatures in poultry liver to back-trace dietary exposure to rapidly metabolized xenobiotics. Environ. Sci. Technol. 2011;45:6584–91.
Theodoridis, G, E. H. M Koster, and G. J de Jong. 2000. “Solid-Phase Microextraction for the Analysis of Biological Samples.” Journal of Chromatography B: Biomedical Sciences and Applications 745 (1): 49–82. doi:10.1016/S0378-4347(00)00203-6.
Hakim, Meggie, Yoav Y. Broza, Orna Barash, Nir Peled, Michael Phillips, Anton Amann, and Hossam Haick. 2012. “Volatile Organic Compounds of Lung Cancer and Possible Biochemical Pathways.” Chemical Reviews 112 (11): 5949–66. doi:10.1021/cr300174a.
Xu, Chang-Hua, Guo-Sheng Chen, Zhen-Hai Xiong, Yu-Xia Fan, Xi-Chang Wang, and Yuan Liu. 2016. “Applications of Solid-Phase Microextraction in Food Analysis.” TrAC Trends in Analytical Chemistry 80 (June): 12–29. doi:10.1016/j.trac.2016.02.022.
