RESUMEN
Rainwater samples from four municipalities located in Achaia Prefecture, Greece, were collected from March to September 2006. The toxic potency of pollutants present in 36 rainwater samples was tested using Daphnia pulex. The pesticide determination was conducted with GC-MS. Only phosphamidon was detected, which appeared in 52% and 13% of the rural and urban areas, respectively. The toxicity of rainwater was determined in 52% and 46.7% of the rural and urban area samples, respectively. Chemical analyses showed that in rural areas, the PO(4)(3-) ions had higher concentrations than in urban areas. On the other hand, the SO(4)(2-), NO(-)(3), and NO(-)(2) anions are more highly concentrated in urban areas. Correlation analysis proved that the toxicity of the rainwater samples is moderate, affected by the presence of the insecticide only in the rural areas. The results indicated that toxicity can be directly assessed via bioassays, even when unknown pollutants are present.