Verification of contamination by dimetoato and aldicarb in liver of Nile tilapias (Oreochromis niloticus) collected in two cold-storages in the State of Paraná.

The importance of fish as a protein source in food is unquestionable , but its role as an indicator of environmental contamination is also very important. This study aimed to analysis the livers of Nile tilapia ( Oreochromis niloticus ), collected from commercial cold-storages in two municipal districts in the State of Parana, for investigation of contamination by organophosphorus compounds and carbamates. It was collected 30 samples of Nile tilapias ( O. niloticus ) liver in the cold-storage A and 45 samples in the cold-storage B, totaling 75 samples. At each location were three visits, and at random, collected the samples from July 2006 to May 2007. For extraction and analysis of samples it was used the qualitative methodology of Thin Layer Chromatography (TLC). Patterns of organophosphate and carbamate used in the analysis of the TLC were respectively Dimethoate and Aldicarb. Of the samples tested were found cabarmate in seven samples, one of the samples collected in the cold-storage A and six collected in the cold-storage B. The organophosphate compound was found in fifteen samples from 75 samples, seven of the cold-storage A and eight samples from the cold-storage B.  The results infer the possibility of contamination of the tanks in the creation of farms and the need for constant monitoring for the presence of residues of pesticides in this important food matrix.