Toxicity and degradation of metolachlor (Dual Gold 960 EC) in chicken embryos.

The herbicide formulation Dual Gold 960 EC (960 g/l metolachlor) was applied, ROSS 308 embryonated hen eggs were treated on day 12 of incubation period. The pesticide was diluted in water to a concentration level 0.3% and the emulsion was injected into the air space in a volume of 0.1 ml/egg, or hen's eggs were treated by the immersion technique (30 min). Residues of metolachlor were measured by GC in 14 collected embryo samples on days 13, 15 and 19 of the incubation of chicken embryos, and macro- and microscopic morphological examinations of 49 embryos were performed simultaneously on day 19. Body mass of embryos was weighed on 13th, 15th and 19th day of incubation. After the both treatments the mortality rate of embryos was similar. The average data of body mass showed a significant decrease compared to the control in the immersion study on day 15 and 19 of the hatching period. This phenomenon may only be in connection with the presence of metolachlor over the limit of quantification (LOQ) on day 13 of incubation period. The macroscopic deformations were sporadic in the embryos. No histologically detected alterations were seen.