الفهرس 
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Abstract
It is known that river Nile and its canals are polluted with industrial, agricultural and sewage wastes. So, the current study was performed to declare the degree of pollution with cadmium, copper, iron, lead and mercury in the flesh and edible parts of fish (head, trunk and tail) and in water of river Nile at Gharbia govenorate.
Therefore, a total of one hundred and twenty samples of both Tilapla nilotica and Clarias lazera were harvested by fishermen by a mean of a fishing net at Tanta, Kafr El Zayat and El Santa at Gharbia governorate.
Thirty random samples of 1:11.a214 nilotica and Clarias lazera (15 of each) were harvested from the same areas for
detection of the same heavy metals in head, trunk and tail parts of fish.
Furthermore, thirty the fresh water samples were collected from the Nile river from the same areas of harvested fish were examined for the presence of the same heavy metals .
All samples of both fish and water are examined using Atomic Absorption Spectrophotometer (Perkin Elmer, Model 2380, U.S.A.) and all values were reported as ppm (mg/Kg)
wet weight, for fish samples and as ppm (mg/L) for water samples.
The results displayed that overall mean values for cadmium, copper, iron, lead and mercury in flesh of T. nilotica harvested from Gharbia governorate, were o.o54 ± o.005,
o.304 ± 0.089, 6.117 ± 0.456, 0.628 ± 0.156 and 2.037 ± 0.245 ppm, respectively whilemean in flesh of C.lazera, the overall mean valus for the same heavy metal residues were 0.053 ± 0.007, 0.53 ± 0,126, 6.45 ± 0.451, 0.64 ± 0.103 and 1.99 ± 0.297 ppm, respectively.
Sixty percent of all Tilapia nilotica samples harvested from Gharbia governOrate contained lead exceed the safe permissible limits followed by mercury (51.11%) then cadmium (11.11%). Whilemean, 13.33%, 64.44% and 66.67% of Clarias lazera flesh samples harvested from the same governorate contained cadmium, lead and mercury exceeding the safe permissible limits, respectively.
Both Tilapia nilotica and Clarias lazera samples had copper content within the safe permissible limits. No copper poisoning occure as a result of fish consumption as it does not bioacummulate in fish. With respect to iron, no available information about its permissible limits in seafoods.
With respect to the residual analysis of heavy metals in head, trunk and tail samples of both Tilapia nilotica and Clarias lazera, the results indicated that head samples had higher mean values of the examined heavy metals than in trunk and tail samples in both Tilapia nilotica and Clarias lazera. The overall mean values for cadmium, copper, iron, lead and mercury in head trunk and tail samples of T.nilotica were 0.042 ± 0.009, 0.626 ± 0.094, 2.273 ± 0.221, 0.414 ± 0.095 and 0.694 ± 0.122 ppm, respectively, while in C. lazera
were 0.053 ± 0.007, 0.53 ± 0.126, 6.45 ± 0.451, 0.64 ± 0.103 and 1.99 ± 0.297 ppm, respectively.
A high significant differences (<0.01) were present between the levels of cadmium, copper, lead and mercury of head , trunk and tail samples of both Tilapia nilotica and Clarias lazera. However, the defferences between the parts of examined fish for iron appeared non significant.
Concerning the head,trunk and tail samples of Tilapia nilotica, the present results declared that (15.56%) of these samples contained cadmium and mercury exceeding the safe permissible limits, while lead exceeded the safe permissible limits in 48.89% of the sampls.
Furthermore, over all mean values of heavy metals in water samples collected from Gharbia governorate were 0.016 ± 0.002, 0.145± 0.063,1.353 ±0.267,0.211+0.047 and 1.07+0.269 ppm for cadmium, copper, iron , lead and mercury, respectively, moreover, (90%),(86.67%), (70%) and of collected water samples from Gharbia governorate contained iron, mercury, lead and cadmium, respectively, exceeded the guideline value of (WHO, 1984) . The high content of heavy metals in these water samples may cause health toxicological problems for human, in addition to high levels of iron in water can cause staining of laundry and pocelain. A bitter sweet astringent taste is detect able by some persons at levels above lmg/L (APHA,1985) also the presence of copper in water, although not constituting a hazard to health, may interfere with domestic uses of water causing corrosion of aluminium
and zinc utensils and staining laundry when copper concent
ration in water exceeds 1.0mg/litre and this value is recommended as a guideline value (VH0,1984).
The public health significance and suggested recommendations are discussed and same recommendations are set for prevention the pollution of river Nile with heavy metals, and for the protection of fish consumers.