1. sports
2. fishing

‫‪ISSN 0021-1907‬‬
‫‪INIS ISRRAC EG‬‬
‫‪ISOTOPE & RAD. RES., 36, 2, 377-390 (2004).‬‬
‫‪CONTAMINATION WITH HEAVY METALS AND‬‬
‫‪BACTERIA IN SOME LOCAL AND IMPORTED‬‬
‫∗ ‪FISH AND FISH PRODUCTS‬‬
‫‪SALEM, S.B., EL-SHOURBAGY, G.A.*, EL-DASHLOUT, A.A.,‬‬
‫*‪EL-SCHIWEE, M.A. and IBRAHIM, R.E.‬‬
‫‪Food Science Dept., Fac. Agric., Zagazig University, Zagazig, Egypt.‬‬
‫‪* Meet and Fish Technology Department, FTRI, ARC, Giza, Egypt.‬‬
‫‪Keywords: Heavy metals pollution, Bacterial contamination,‬‬
‫‪Contaminated fish.‬‬
‫اﻟﺘﻠﻮث ﺑﺎﻟﻌﻨﺎﺻﺮ اﻟﺜﻘﻴﻠﺔ واﻟﺒﻜﺘﺮﻳﺎ ﻓﻰ ﺑﻌﺾ اﻷﺳﻤﺎك واﻟﻤﻨﺘﺠﺎت اﻟﺴﻤﻜﻴﺔ‬
‫اﻟﻤﺤﻠﻴﺔ واﻟﻤﺴﺘﻮردة‬
‫ﺻﺒﺤﻰ ﺑﺴﻴﻮﻧﻰ ﺳﺎﻟﻢ وﺟﻴﻬﺎن ﻋﺒﺪ اﷲ اﻟﺸﻮرﺑﺠﻰ وأﻣﺎﻧﻰ ﻋﺒﺪ اﷲ اﻟﺪﺷﻠﻮﻃﻰ‬
‫وﻣﺪﻳﺤﺔ ﻋﺒﺪ اﻟﺠﻮاد اﻟﺸﻴﻮى ورﺑﺎب اﻟﺴﻌﻴﺪ إﺑﺮاهﻴﻢ‬
‫ﺧﻼﺻـــﺔ‬
‫ﻓﻰ هﺬﻩ اﻟﺪراﺳﺔ ﺗﻢ ﺗﻘﻴﻢ وﺟﻮد ﺑﻌﺾ اﻟﻌﻨﺎﺻﺮ اﻟﺜﻘﻴﻠﺔ )اﻟﺮﺻﺎص – اﻟﻜﺎدﻣﻴﻮم – اﻟﺰﺋﺒ ﻖ( واﻟﺘﻠ ﻮث‬
‫ﺑﺎﻟﺒﻜﺘﺮﻳﺎ ﻓﻰ ﻋﻴﻨﺎت ﻣﻦ اﻷﺳﻤﺎك واﻟﻤﻨﺘﺠﺎت اﻟﺴﻤﻴﻜﺔ واﻟﺘﻰ ﺗﺴﺘﻬﻠﻚ ﻓﻰ ﺛﻼﺛﺔ أﺳﻮاق ﻣﺤﻠﻴﺔ ﺑﺜﻼث ﻣ ﺪن‬
‫آﺒﻴﺮة ﻓﻰ ﻣﺤﺎﻓﻈﺔ اﻟﺸﺮﻗﻴﺔ ﻣﺼﺮ‪.‬‬
‫ﺗﺸﻴﺮ اﻟﻨﺘﺎﺋﺞ اﻟﻤﺘﺤﺼ ﻞ ﻋﻠﻴﻬ ﺎ إﻟ ﻰ أن ﺗﺮآﻴ ﺰ اﻟﺮﺻ ﺎص ﻓ ﻰ ﻋﻴﻨ ﺎت اﻷﺳ ﻤﺎك اﻟﻄﺎزﺟ ﺔ واﻟﻤﺠﻤ ﺪة‬
‫واﻟﻤﻤﻠﺤﺔ واﻟﻤﺪﺧﻨﺔ واﻟﻤﻌﻠﺒﺔ )ﻣﻦ اﻟﺒ ﻮرى‪ ،‬اﻟﺴ ﺮدﻳﻦ‪ ،‬اﻟﻤﻜﺮوﻧ ﺔ‪ ،‬اﻟﻤﺎآﺮﻳ ﻞ‪ ،‬اﻟﺘﻮﻧ ﺔ‪ ،‬اﻟﺴ ﻬﻠﻴﺔ‪ ،‬اﻟﺮﻧﺠ ﺔ(‬
‫آ ﺎن أﻗ ﻞ ﻣ ﻦ اﻟﺤ ﺪ اﻟﻤﺴ ﻤﻮح ﺑ ﻪ ﻃﺒﻘ ًﺎ ﻟﻠﻤﻮاﺻ ﻔﺎت اﻟﻘﻴﺎﺳ ﻴﺔ اﻟﻤﺼ ﺮﻳﺔ ﻟﻌ ﺎم ‪ 1993‬وه ﻮ‬
‫‪ 0.1‬ﻣﻠﻠﻴﺠﺮام‪/‬آﺠﻢ‪ .‬ﻣﻦ ﻧﺎﺣﻴﺔ أﺧﺮى أﻇﻬ ﺮت اﻟﺪراﺳ ﺔ أن آ ﻞ اﻟﻌﻴﻨ ﺎت اﻟﻤﺘﺤﺼ ﻞ ﻋﻠﻴﻬ ﺎ ﻣ ﻦ اﻷﺳ ﻤﺎك‬
‫آﺎﻧﺖ ﺗﺤﺘﻮى ﻋﻠﻰ ﻣﺴﺘﻮى ﻋﺎﻟﻰ ﻣ ﻦ اﻟﻜ ﺎدﻣﻴﻮم )‪ 0.41 - 0.29‬ﻣﻠﻠﻴﺠ ﺮام ‪ /‬آﺠ ﻢ( أﻋﻠ ﻰ ﻣ ﻦ اﻟﻤﺴ ﻤﻮح‬
‫ﺑ ﻪ ﻃﺒﻘ ًﺎ ﻟﻠﻤﻮاﺻ ﻔﺎت اﻟﻤﺼ ﺮﻳﺔ )‪ (1993‬وه ﻮ ‪ 0.1‬ﻣﻠﻠﻴﺠ ﺮام‪ /‬آﺠ ﻢ وه ﺬا اﻟﺤ ﺪ اﻟﻤﺼ ﺮى ﻳﺠ ﺐ إﻋ ﺎدة‬
‫اﻟﻨﻈ ﺮ ﻓﻴ ﻪ ﺧﺼﻮﺻ ًﺎ أن اﻟﺤ ﺪود اﻟﻤﺴ ﻤﻮح ﺑﻬ ﺎ ﻣ ﻦ ﻗﺒ ﻞ ﻣﻨﻈﻤ ﺔ اﻟﺼ ﺤﺔ اﻟﻌﺎﻟﻤﻴ ﺔ )‪ (1992‬ه ﻰ ‪0.5‬‬
‫ﻣﻠﻠﻴﺠﺮام ‪ /‬آﺠﻢ ﻣﻦ اﻟﻜﺎدﻣﻴﻮم‪ .‬أﻣﺎ ﻣﺴﺘﻮى اﻟﺰﺋﺒﻖ ﻓﻰ ﻋﻴﻨﺎت ﺳ ﻤﻚ اﻟﺒ ﻮرى ﻓﻜ ﺎن ﻣﺴ ﺎوى ﻟﻠﻤﻮاﺻ ﻔﺎت‬
‫اﻟﻤﺼﺮﻳﺔ )‪ 0.5‬ﻣﻠﻠﻴﺠﺮام ‪ /‬آﺠﻢ( ﺑﻴﻨﻤﺎ آﺎن اﻟﻤﺴﺘﻮى ﻓﻰ ﻋﻴﻨﺎت اﻷﺳﻤﺎك اﻟﻤﺠﻤﺪة واﻟﻄﺎزﺟ ﺔ واﻟﻤﻤﻠﺤ ﺔ‬
‫واﻟﻤﺪﺧﻨﺔ أﻋﻠﻰ ﻣﻦ اﻟﻤﺴﻤﻮح ﺑﻪ وﻓ ﻰ ﻣﻌﻈ ﻢ اﻟﺤ ﺎﻻت آﺎﻧ ﺖ ﻣﻨﺘﺠ ﺎت اﻷﺳ ﻤﺎك اﻟﻤﻌﻠﺒ ﺔ اﻟﻤﺴ ﺘﻮردة ﻣ ﻦ‬
‫اﻟﺴﺮدﻳﻦ واﻟﻤﺎآﺮﻳﻞ واﻟﺘﻮﻧﺔ ذات ﻣﺤﺘﻮى ﻋﺎﻟﻰ ﻣﻦ اﻟﺮﺻﺎص واﻟﻜﺎدﻣﻴﻮم واﻟﺰﺋﺒﻖ ﻋﻤﺎ هﻮ ﻣﻮﺟ ﻮد ﻓ ﻰ‬
‫اﻟﻤﻨﺘﺠﺎت اﻟﻤﺤﻠﻴﺔ‪.‬‬
‫أﻣ ﺎ ﻓﻴﻤ ﺎ ﻳﺨ ﺺ اﻟﺠ ﻮدة ﻣ ﻦ اﻟﻨﺎﺣﻴ ﺔ اﻟﻤﻴﻜﺮوﺑﻴﻮﻟﻮﺟﻴ ﺔ ﻟﻸﺳ ﻤﺎك اﻟﻤﺤﻠﻴ ﺔ واﻟﻤﺴ ﺘﻮردة واﻟﻤﻌﺎﻣﻠ ﺔ‬
‫ﺑﻄﺮق ﻣﺨﺘﻠﻔﺔ ﻓﻘﺪ أﻇﻬﺮت اﻟﻨﺘﺎﺋﺞ أﻧﻪ ﻣﻦ اﻷﺳﻤﺎك اﻟﻄﺎزﺟﺔ آﺎن ﺳﻤﻚ اﻟﻤﻜﺮوﻧﺔ اﻟﻄﺎزﺟﺔ ﻳﺤﺘﻮى ﻋﻠﻰ‬
‫أﻋﻠﻰ اﻟﻘﻴﻢ ﻣﻦ اﻟﻌﺪد اﻟﻜﻠﻰ ﻟﻠﺒﻜﺘﺮﻳﺎ‪ ،‬ﺑﻴﻨﻤﺎ ﺳﻤﻚ اﻟﺒﻮرى اﺣﺘﻮى ﻋﻠﻰ أﻗﻞ ﺗﻠﻚ اﻟﻘﻴﻢ‪ .‬ﻓﻴﻤﺎ ﻳﺨﺺ اﻷﺳﻤﺎك‬
‫اﻟﻤﻤﻠﺤﺔ واﻟﻤﺪﺧﻨﺔ ﻓﻘﺪ اﺣﺘﻮت ﻋﻴﻨﺎت اﻟﺒﻮرى ﻋﺎﻟﻴ ﺔ اﻟﺘﻤﻠ ﻴﺢ ﻋﻠ ﻰ أﻋﻠ ﻰ اﻟﻘ ﻴﻢ ﻣ ﻦ اﻟﻌ ﺪد اﻟﻜﻠ ﻰ ﻟﻠﺒﻜﺘﺮﻳ ﺎ‬
‫ﺑﻴﻨﻤﺎ أﻇﻬﺮت ﻋﻴﻨﺎت اﻟﺴﺮدﻳﻦ أﻗﻞ ﺗﻠﻚ اﻟﻘ ﻴﻢ آﻤ ﺎ أﻇﻬ ﺮت ﻋﻴﻨ ﺎت اﻟﺮﻧﺠ ﺔ اﻟﻤﺪﺧﻨ ﺔ أﻗ ﻞ اﻟﻘ ﻴﻢ ﻣ ﻦ اﻟﻌ ﺪد‬
‫اﻟﻜﻠﻰ ﻟﻠﺒﻜﺘﺮﻳﺎ ﻣﻘﺎرﻧﺔ ﺑﺎﻟﺴﺮدﻳﻦ اﻟﻤﻤﻠﺢ‪.‬‬
‫‪Accepted in August 2004.‬‬
378
SALEM, S.B. et al.,
‫ أﻇﻬ ﺮت اﻟﻨﺘ ﺎﺋﺞ أﻧ ﻪ ﻻ ﻳﻮﺟ ﺪ ارﺗﺒ ﺎط ﺑ ﻴﻦ ﻧ ﻮع اﻟﺴ ﻤﻚ أو ﻣﻜ ﺎن اﻻﺳ ﺘﻬﻼك وﻣ ﺪى‬،‫ﺑﺼ ﻔﺔ ﻋﺎﻣ ﺔ‬
.‫اﻟﺘﻠﻮث ﺑﺎﻟﻌﻨﺎﺻﺮ اﻟﺜﻘﻴﻠﺔ أو اﻟﺘﻠﻮث ﺑﺎﻟﺒﻜﺘﺮﻳﺎ ﺗﺤﺖ اﻟﺪراﺳﺔ‬
ABSTRACT
Some local and imported fish and fish products sold in retail markets of
three cities at Sharkia Governorate, Egypt, were examined against heavy
metals contamination (i.e. Pb, Cd and Hg) and the presence of some specific
groups of bacteria. The results showed that concentrations of Pb in fresh
and frozen fish, salted and smoked fish and canned fish samples were lower
than the permissible limits recommended by the Egyptian Organization 1993
(1.0 mg/kg). On the other hand, all the tested fish and fish products of
collected samples showed levels of Cd (0.29-0.41 mg/kg) higher than the
permissible limit (0.10 mg/kg) recommended by the Egyptian Organization.
Such limits should be re-considered because the limit determined by WHO
(1992) was 0.5 mg/kg. Mercury level in fresh mullet was equal or lower
(0.46-0.50 mg/kg) than the limit of Egyptian Organization (0.50 mg/kg)
while other fresh and frozen fish, salted and smoked fish samples had higher
Hg than the allowance. In most cases, imported canned products of sardine,
mackerel and tuna had higher Pb, Cd and Hg concentrations than that found
in the local ones. Among fresh fish samples, such as mackarona, contained
the highest total bacterial count, while mullet was the lowest. Considering
salted and smoked fish, heavy salted mullet had the highest total bacterial
count, while the lowest number was recorded in salted sardine. Smoked
herring showed lowest total bacterial count than salted samples. Generally,
no correlation was observed between fish species or consumption place and
the contamination with heavy metals and bacteria.
INTRODUCTION
Pollution of the aquatic environment with heavy metals has become a
serious health concern during recent years. Untreated municipal and
industrial wastes together with inputs from the atmosphere are the major
sources of metal pollution, especially in areas in close vicinity to industrial
and agricultural activities. Industrial and agricultural discharges are
considered the primary source of metal poisoning in Egypt (El-Nabawi et al.,
1987).
Fish have the ability to accumulate heavy metals in their tissues by the
absorption along the gill surface and wall of gut tract to higher levels which
are several hundred times more than the concentration of metals in their
surrounding water medium. Generally, fresh-water fish are more sensitive to
metals than marine species (Nammalwar, 1983 and Sorenson, 1991).
Mercury (Hg), cadmium (Cd) and lead (Pb) are among the most dangerous
of these metals. Cadmium causes I.tai-I.tai byo disease with bone and
muscle pain. It also injure the kidney causing symptoms of chronic toxicity
including impaired kidney function. Also, poor reproductive capacity,
hypertension, tumours and hepatic dysfunction may observed (Gossel and
CONTAMINATION WITH HEAVY METALS …
379
Bricker, 1990). Moreover, lead toxicity has probably plagued humans since
early civilization. Chronic lead poisoning (plubism) may induce anemia,
abdominal pain (lead cholic), encephalopathy, renal and liver damage
(Gosssel and Bricker, 1990).
The concentrations of these metals in the canned seafood depend on the
type and origin of food, pH of the products, oxygen concentration in the
head space, storage time, quality of inside lacquer coating of the cans as well
as temperature and humidity of storage place. Furthermore, curing as the
most popular preserving method of fish in developing countries is carried out
using crude solar salt which is normally produced from sea or salt lake
water. Unless processing is carefully controlled, solar salt is the most impure
natural crude salt and the traces of heavy metals are the major contaminants
(Horner, 1992 and Oduoze, 1992). According to FAO/WHO (1992), the
maximum permissible limit for Hg, Cd and Pb was 0.5, 0.5 and 0.05 ppm,
respectively, in fish for human consumption.
Not only the level of heavy metals but also the bacterial break down
affects the quality of sea food. Among the most important bacterial groups
affecting sea food quality are psychrophilic bacteria, halophilic bacteria and
histamine producing bacteria. The presence of these bacteria was likely to be
as a result of contamination of fish from different sources during capture,
handling, transporting, marketing and unhygienic handling in the processes.
According to the Egyptian Organization (2003), the limit of total bacterial
count must not exceed 106 per gram.
The study was preformed to evaluate the quality and safety of fish and
fish products (commonly consumed in Egypt) by estimating the levels of
some important heavy metals and bacteria that contaminate fish and fish
products.
MATERIALS AND METHODS
1- Materials:
Fish and fish products used in this study were purchased from local
markets of Zagazig, Abu-Kabeer and Abu-Hammad cities, Sharkia
Governorate, Egypt, during the period between May and September 1997.
They included fresh mullet (Mugilidae mugil cephalus), fresh sardine
(Clupidar sardinella Val), fresh makarona (Saurus spp.), imported frozen
hors mackerel (Carangide trachurus trachurus), salted mullet, salted
sardine, salted seheli (Mugile spp.), smoked herring (Clupea harengus) and
canned tuna, mackerel and sardine.
2- Methods:
2.1. Heavy metal determinations:
Heavy metals (lead, cadmium and mercury) were determined according
to the method of Diaz et al., (1994). Half gram of macreated fish sample was
380
SALEM, S.B. et al.,
digested in 10ml solution of concentrated H2SO4/HNO3 (1:1) at 45°C for 15
hr. Resultant digest was cooled, diluted, filtered and the volume was
completed to 100 ml with de-ionized water. The filterate was then analyzed
by Flame Atomic Absorption Spectrophotometer, Perkin Elmer, mode 2380,
U.S.A. The same steps (without fish sample) was followed to prepare blank
solution.
2.2. Bacteriological determinations:
Ten grams of ground representative fish sample was mixed with 90 ml of
sterilized physiological saline solution (8.5 gm NaCl/liter distilled water).
The mixture was blended in sterilized blender jar until a homogenate
suspension was obtained, which provides a dilution of 10-1. One ml from this
dilution was pipetted in sterilized test tubes containing 9 ml of physiological
solution to obtain dilution of 10-2. The last step was repeated until the
required number of dilutions was made (10-8). Total aerobic bacterial count
(TBC) was adopted according the method described by APHA (1992) using
nutrient agar medium.
RESULTS AND DISCUSSION
1. Contamination by heavy metals
1.1. Fresh and frozen fish
Figures (1a, b, c) show the concentrations (mg/kg) of lead (Pb), cadmium
(Cd) and mercury (Hg) in fresh and imported frozen fish. The results
indicated that the concentrations of lead (fig. 1a) in samples collected from
the markets of Zagazig, Abu-Kabeer and Abu-Hammad were ranged
between 0.032 to 0.063, 0.050 to 0.061 and 0.046 to 0.063 mg/kg,
respectively. These values were relatively lower than the permissible limit
(0.1 mg/kg) recommended by the Egyptian Organization (1993) and higher
than the level (0.05mg/kg) recommended by FAO/WHO (1992) except for
fresh mullet (fig. 1a). Meanwhile, the results showed that the higher Pb
concentrations of mullet, sardine, makarona and frozen mackerel were found
in Zagazig, Abu-Hammad, Abu-Kabber cities, respectively. Abu-Arab et al.,
(1996) found that the imported sardine and mackerel had levels of Pb than
the permissible limits proposed by FAO/WHO (1992). This was also
observed in the collected samples of the present work.
The concentrations of cadmium in fresh and imported frozen fish were
ranged between 0.29 and 0.41 mg/kg (fig. 1b). These values were higher
than the permissible limit (0.1 mg/kg) of the Egyptian Organization (1993)
and lower than the limit (0.5 mg/kg) proposed by FAO/WHO (1992). The
values of Cd presented in fig. (1b) were lower than that reported by Tariq
et al., (1994) and agreed with the results of Abu Arab et al., (1996). As
reported by Eman (2001), the range of Cd in El-Manzala bolti fish flesh was
0.02-0.05 mg/kg, while it was 0.3395-0.4670 mg/kg in bolti fish flesh of
CONTAMINATION WITH HEAVY METALS …
381
Shibin El-Kom Canal, Menufiya Governorate (Osheba, 1998). It seems that
fish landed from water near field and farms which use special fertilizers may
be contaminated with cadmium. Regarding fig. (1b), it could be stated that
the higher concentration of Cd of fresh mullet, fresh sardine, fresh makarona
and frozen markerel were found in Abu-Kabeer, Abu-Hammad and Zagazig
cities, respectively.
Concerning the contamination with mercury, fig. (1c), it could be
observed that fresh mullet contained the lowest values of Hg (0.46-0.50
mg/kg), which considered below or similar to the permissible limit (0.50
mg/kg) recommended by the Egyptian Organization (1993). Meanwhile,
imported frozen mackerel had the higher Hg values (0.61-0.65 mg/kg)
followed by fresh sardine (0.54-0.60 mg/kg) and fresh makarona (0.51-0.55
mg/kg). It is evident that the fresh fish of Abu-Kabeer city was more
contaminated by Cd, while Abu-Hammad samples had the lower
contamination. The levels of Hg (fig. 1c) were found between the results
reported by Moharram et al., (1987), Rieder (1993) and Sangiorgi and
Ferretti (1993).
1.2. Salted and smoked fish
Figures (2a, b, c) show the concentrations of Pb, Cd and Hg in heavy and
mild salted mullet, salted sardine, salted seheli and smoked herring.
The results of fig. (2-a) show that the concentration of lead in salted fish
ranged from 0.047 to 0.066 mg/kg, which was less than the maximum
permissible limit of the Egyptian Organization (1993), but in many cases
was higher than FAO/WHO (1992) limits. Such findings were similar to
382
SALEM, S.B. et al.,
(a)
0.07
mg/kg wet weight
0.06
0.05
0.04
0.03
0.02
0.01
0
Fresh mullet
Zagazig city
Fresh sardine
Fresh makarona Frozen mackerel
Abu-Kabeer city
Abu-Hammad city
Lead
(b)
0.45
0.4
mg/kg wet weight
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
Fresh mullet
Fresh sardine
Zagazig city
Abu-Kabeer city
Fresh makarona Frozen mackerel
Abu-Hammad city
Cadmium
(c)
0.7
mg/kg wet weight
0.6
0.5
0.4
0.3
0.2
0.1
0
Fresh mullet
Zagazig city
Fresh sardine Fresh makarona Frozen mackerel
Abu-Kabeer city
Abu-Hammad city
Mercury
Fig. (1a,b,c): Concentrations of lead, cadmium and murcury
in fresh and frozen fish.
CONTAMINATION WITH HEAVY METALS …
(a)
0.07
mg/kg wet weight
0.06
0.05
0.04
0.03
0.02
0.01
0
Heavy
salted
mullet
Zagazig city
Mild salted
mullet
Salted
sardine
Abu-Kabeer city
Salted
seheli
Smoked
herring
Abu-Hammad city
Lead
(b)
0.5
0.45
mg/kg wet weight
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
Heavy salted
mullet
mg/kg wet weight
Zagazig city
Mild salted
mullet
Salted
sardine
Abu-Kabeer city
Salted seheli
Smoked
herring
Abu-Hammad city
Cadmium
(c)
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Heavy
salted
mullet
Zagazig city
Mild salted
mullet
Salted
sardine
Abu-Kabeer city
Salted
seheli
Smoked
herring
Abu-Hammad city
Mercury
Fig. (2a,b,c): Concentrations of lead, cadmium and murcury
in salted and smoked fish.
383
384
SALEM, S.B. et al.,
those reported by Khalid (1997). The relative higher Pb contaminations were
noticed in salted and smoked herring of Abu Kabeer city (fig. 2a).
In all investigated samples, cadmium metal was found to be more than
the permisssible limit (0.1 mg/kg) of the Egyptian Organization (1993) by
40% (smoked herring - Zagazig city) to 380% (smoked herring – AbuHammad city). Heavy salted mullet of Zagazig and Abu-Kabeer cities had
higher Cd contents than the mild salted mullet which may be attributed to
the loss of much moisture and absorption of NaCl during salting process. In
contrast, heavy salted mullet of Abu-Hammad city had less Cd than the mild
one which may be due to much escaped Cd with the losted moisture.
Moreover, the range of Cd concentrations in salted sardine and salted seheli
were 0.26-0.42 and 0.32-0.44 mg/kg, respectively, and Abu-Kabeer city had
the highest Cd contamination in both samples.
Compared to fresh mullet and fresh sardine (fig. 1c), salting process
showed an increase in the concentration of mercury (fig. 2c) due to moisture
loss and accordingly the increase in total solids and ash contents. Also, the
increase in Hg concentration may be due to the contamination of the
utilized salt by this element. Figure (2c) shows that Hg concentrations of all
samples were more than the limit of the Egyptian Organization (1993) by 24
to 100%. Mild salted mullet possessed the lowest Hg concentration (0.620.67 mg/kg), while the highest concentration (0.98-1.00 mg/kg) was found
in salted seheli followed by smoked herring (0.96-0.98 mg/kg). These
concentrations seems to be higher than those reported by Diaz et al., (1994),
Nassar et al., (1996) and Khalid (1997).
1.3. Canned fish
The levels of Pb, Cd and Hg in local and imported canned fish (tuna,
sardine and mackerel) were illustrated in figures (3a, b, c). Lead
concentrations in all examined canned samples (fig. 3a) were lower than the
permissible limits (1.0 mg/kg) recommended by the Egyptian Organization
(1993). The higher Pb concentration (0.066 mg/kg) was found in imported
mackerel (Abu-Hammad city), while the lowest levels (0.031 mg/kg) was
found in imported mackerel (Abu-Kabeer city).
Relatively, contamination with cadmium (fig. 3b) was higher than the
permissible limit (0.1 mg/kg) of the Egyptian Organization (1993) by 90%
(imported sardine, Abu-Hammad city) to 410% (imported sardine, AbuKabeer city). In imported canned tuna, Cd concentration was ranged
between 0.3 and 0.4 mg/kg. These values were in harmony with those
reported by Schindler (1985). On the other hand, Michalak and Bulinski
(1996) reported that Cd concentrations were above the permissible limit in
98% of the analyzed canned fish samples.
(a)
mg/kg wet weight
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
Imported
canned tuna
Local
canned
Imported
canned
Local
canned
Imported
canned
CONTAMINATION WITH HEAVY METALS …
385
Results of fig. (3c) indicate that the levels of mercury in imported tuna
(except at Abu-Hammad city) and local and imported sardine were higher
than the maximum permissible limits (0.5 mg/kg) of the Egyptian
Organization (1993) being 0.52-0.65, 0.51-0.53 and 0.61-0.63 mg/kg,
respectively. In contrast, local (except at Abu-Kabeer city) and imported
canned mackerel had the lowest Hg values of 0.33-0.35 and 0.46-0.48
mg/kg, respectively. Generally, local canned mackerel and local canned
sardine had less Hg than the imported samples which may reflect the much
more industrial activities in foreign countries leading to water and fish
pollution .
2- Microbial lood
Fresh fish (mullet, sardine and makarona), imported frozen mackerel,
salted fish (heavy and mild mullet, saridne, seheli) and smoked herring were
examined for total aerobic bacterial count (TBC).
2.1. Fresh and frozen fish
Results of table (1) explain the total aerobic bacterial count (TBC) in
fresh and frozen fish. Fresh fish showed variable levels of TBC which seems
to be not affected by fish species or the purchasing city market. In this
respect, Abd El-Aziz (2000) reported that the presence of total bacteria
count in fish of different cities could be due to variations in the conditions,
sanition practices and aspects during handling and marketing inside fishing
markets. Our results revealed that fresh makarona of Zagazig city had the
highest TBC (9.2x107 cfu/g) while imported frozen mackerel of Abu-Kabeer
city had the lowest (9.8x103 cfu/g). Fresh makarona also possessed the
highest TBC among other fishes of the three investigated markets (6.3x1049.2x107cfu/g), while fresh mullet had the lowest TBC (15.2x1031.3x105cfu/g). Abu-Hammad fish market seems to have the lowest TBC
(6.3x104-8.5x104 cfu/g) except for frozen mackerel (5.1x105 cfu/g). In this
concern, Badr (1982) determined high total bacterial count (8.3x106 cfu/g) in
mackerel fish which attributed to the contamination occurred after catching
and during handling.
2.2. Salted and smoked fish
Data of table (2) show the results of TBC of salted (mullet, sardine and
seheli) and smoked herring. It could be noticed that salted mullet and salted
sardine had higher TBC than the fresh samples (table 1). This may be
ascribed to the enumeration of lactic acid bacteria which tolerate the salt.
Meanwhile, heavy salted fish had higher TBC than the mild salted one.
Heavy salted mullet of Abu-Kabeer market had the highest TBC (11.8x108
cfu/g), while the lowest number (10.2x106 cfu/g) was recorded in salted
sardine of Zagazig market. Yaser (1994) reported a range of 15.0x106 to
5.8x107 cfu/g in salted mullet.
386
SALEM, S.B. et al.,
CONTAMINATION WITH HEAVY METALS …
387
Table (3): Total aerobic bacterial count (TBC) from different localities in
smoked fish.
Smoked Fish
Samples
Smoked Herring
Canned Herring
Zagazig
4.6x107
4.6x107
3
Abu-Kabeer
6.1x10
6.1x103
4
Abu-Hammad
3.2x10
3.2x104
Data in table (3) show the determined number of TBC in smoked herring
and canned herring. It could be noticed that smoked fish showed in general,
lower TBC and other tested groups than that found in the tested salted
products, table (2). In this respect, Hammad (1985) reported that smoking
process can reduce total bacterial count of eel from 2.9x105 (fresh) to 1x103
cfu/g (smoked). This means that smoke components are lethal to
microorganisms in addition to the smoking temperature which is greatly
effective in reducing bacteria. The higher TBC was recorded in smoked
herring of Zagazig market followed by Abu-Hammad and Abu-Kabeer
markets. Moghazy (1994) found that smoked herring obtained directly from
the factory has relatively better hygienic status than smoked herring obtained
from El-Azhar area. This could be attributed to the lack of care during
handling.
In all previous fish samples, no correlation was observed between fish
species or consumption place and the contamination with heavy metals and
microorganism. Compared to the permissible limit of the Egyptian
Organization (2003) , 106 cfu/g , about 80% of fish samples must be
rejected. The contamination is mainly due to bad sanition during handling
and marketing of fish and fish products.
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