الفهرس 
CONCLUSION AND RECOMENDATIONSOnly 14 pages are availabe for public view
 |  | from | 108 |  |  |
| | | from | 108 | | |
Abstract
A total of 80 samples of wild tilapia and marketed farmed tilapia (Oreochromis niloticus). Actually, 40 samples represented by 20 large (205:225g) and 20 small fish (90:115g) from different Nile canals and 40 samples of marketed farmed fish represented by 20 large (235:275g) and 20 small fish (105:125g) were collected from different localities at Menoufia governorate, Egypt. All samples were detected for some heavy metals residues as mercury, lead and cadmium by using Atomic Absorption Spectrophotometer (AAS) and detection of some hormones residue as testosterone and trenbolone residues in fish muscles, also to determine the efficacy of different types of heat treatment (grilling for 15 min. and frying for 10 min.) on the stability of the hormones by using Enzyme–Linked Immuno Sorbant Assay method (ELISA).
The obtained results revealed that the mercury residues were detected in (8) 40%, (11) 55%, (6) 30% and (8) 40% of samples with mean values of 0.73±0.09, 1.18±0.12, 0.45 ±0.06 and 0.94±0.10 mg/kg where lead residues were detected in (6) 30%, (9) 45%, (4) 20% and (7) 35% of samples with mean of o.34±0.05, 0.54±0.07, 0.25±0.04 and 0.29±0.03 mg/kg and cadmium residues were detected in (5) 25%, (7) 35%, (4) 20% and (5) 25% of samples with mean of 0.10±0.01, 0.15±0.02, 0.05±0.01 and 0,08±0.03 mg/kg in small wild, large wild, small farmed and large farmed tilapia samples respectively. The obtained results also revealed that testosterone residues were detected in all 80 (100%) samples (100%) with mean values of 0.96±0.08, 1.52±0.14, and 3.48±0.27 and 1.93±0.19 mg/kg in small wild, large wild, small farmed and large farmed tilapia samples respectively. Trenbolone residues not detected in small wild and large wild tilapia but for small farmed and large farmed tilapia samples were detected in (9) 45% and (6) 30%of samples with mean values of 0.37±0.03 and 0.18±0.01 mg/kg. The results indicated that grilling was the best method of fish cooking which reduced these fat-soluble hormones testosterone and trenbolone hormone.
The public health significance of these residues as well as the recommendations to safeguard fish consumers from such toxic residues were discussed.