Reactivity of singlet oxygen with neonicotinoid insecticides: mechanism and changes in toxicity

M. L. DELL'ARCIPRETE; L. SANTOS-JUANES; A. ARQUES; A. M. AMAT; D. O. MÁRTIRE; M. C. GONZALEZ

Toledo, Espana

Conferencia; International Conference of Photochemistry; 2009

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:72.0pt 90.0pt 72.0pt 90.0pt; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Pesticides are of environmental concern due to the serious effect they produce on aquatic ecosystems, even at low concentrations. These species might remain for long periods in water, where they can react to generate by-products which could be expected to show different biocompatibility than the parent compound. There are an important number of reactive systems that can be found in natural waters. In particular, the study of the reactivity of singlet oxygen (1O2) with pesticides is interesting as they are highly oxidizing and may modify substantially the structure of the organics. Under natural conditions the steady state concentration of these radicals is <10-12 M and thus, mineralization or strong oxidation is not expectable, and only primary photo-oxidation products are likely to be found. With this background, we investigated the primary steps in the 1O2-driven oxidation of imidacloprid, acetamiprid and thiacloprid which are a novel group of insecticides increasingly employed because of their selective toxicity for insects over vertebrates.