Influence of UV irradiation on the toxicity of phenylurea herbicides using Microtox test.
Halogenated phenylurea herbicides are not very toxic by themselves to animals, but their exposure to UV light may significantly increase the toxicity of their solutions. Absorption of light may indeed induce a phototransformation of the herbicide with a possible formation of more toxic intermediate photoproducts. Fortunately in environmental conditions photolysis is usually slow and photoproducts do not accumulate appreciably. Microtox was used for the evaluation of the toxicity of the crude irradiated solutions of some phenylurea herbicides. The sharp initial increase of toxicity shown by metobromuron solutions is mainly due to intermediate photoproducts which rapidly disappear. In the case of diuron and metoxuron toxicity is due to minor photoproducts and it does not disappear so rapidly. Hence the decrease of herbicide concentration is not necessarily associated to a lower toxicity of the solution.
Bonnemoy
F
F
Laboratoire de Biologie Comparée des Protistes, Université Blaise Pascal, CNRS UMR 6023, Aubière 63177, France. frederique.bonnemoy@lbp.univ-bpclermont.fr
Lavédrine
B
B
Boulkamh
A
A
D004237:Diuron / Q000528:radiation effects / Q000633:toxicity; D005453:Fluorescence; D006540:Herbicides / Q000528:radiation effects* / Q000633:toxicity*; D007700:Kinetics; D008782:Methylurea Compounds / Q000528:radiation effects / Q000633:toxicity; D010671:Phenylurea Compounds / Q000737:chemistry / Q000528:radiation effects* / Q000633:toxicity*; D010782:Photolysis; D018675:Toxicity Tests / Q000379:methods; D014466:Ultraviolet Rays; D014733:Vibrio / Q000737:chemistry / Q000187:drug effects
D006540:Herbicides; D008782:Methylurea Compounds; D010671:Phenylurea Compounds; C008770:metobromuron; D004237:Diuron; C454323:3-(3-chloro-4-methoxyphenyl)-1,1-dimethylurea