Organochlorine and anticholinergic pesticides in wild mice from wetland ecosystems of the Gulf of Mexico

Terminos Lagoon area is a highly important economic and biological area, and one of the most important fresh water reservoirs in Mesoamerica. This area has been affected by human activities such as the disposal of pollutants, including pesticides that cause damage among wildlife. Our research evaluated the exposition of three wild rodent species Oryzomys couesi, Peromyscus leucopus, and Reithrodontomys gracilis to organochlorine and anticholinergic pesticides in nine localities of Terminos Lagoon. We collected samples of brain, skeletal muscle, and liver to evaluate organochlorine and anticholinergic pesticides exposure. We measure acetylcholinesterase (AChE) activity as anticholinergic pesticide exposure sign. We found significant differences in acetylcholinesterase activity among localities in brain for two species O. couesi and R. gracilis , but not for skeletal muscle tissue. We found 20 organochlorine compounds in rodent´s liver of which only lindane, aldrine and heptachlor were in amounts suggesting a recent exposure. The AChE inhibition is not enough evidence for anticholinergic pesticide exposure. Recent organochlorine pesticides application and exposition was detected, but sources are unknown, probably atmospheric deposition. Rodent exposure to pesticides could affect negatively its population dynamic. This detrimental effects can reach higher trophic levels because predators biomagnifies some of these compounds.