A Study of Heavy Metals Pollution in Some Aquatic Organisms... Suez Canal in Port- Said Harbour

Journal of Applied Sciences Research, 2(10): 657-663, 2006
© 2006, INSInet Publication
A Study of Heavy Metals Pollution in Some Aquatic Organisms in
Suez Canal in Port- Said Harbour
Zienab I. Soliman
Agriculture Research Center, Animal Health Research Institute, Dokki, Cairo,
Egypt-Port Said Lab.of Food Hygiene.
Abstract: The northern Harbor of Port Said at inlet of Suez Canal in the Mediterranean Sea, with its dense ship
traffic receives several types of hazardous chemical pollutants affecting dramatically its water. The aims of this
study was to determine the current levels of total mercury, cadmium and zinc in edible muscles tissues of
different marine organisms caught in Suez Canal to ascertain whether these concentrations exceeded the
prescribed legal limits and to identify any potential public health risks that could be associated with dietary
intakesof seafood from Suez Canal. Three groupsof aquatic organisms,including fish: mullet (Mugil cephalus)
and sardine (Sardine pilshardus), crustacea: crab (Calinictus sapidus) and shrimps (Metapenaeus nonoceras)
and Molluscan cephalopods: cuttlefish (Sepia spp.) and squid (Loligo spp.) were analyzed for their content of
total mercury, cadmium and zinc. The total mercury concentrations in the edible muscles tissues of fish species
were ranged from 0.18 to 1.17 ppm (wet weight) while levels of 0.01 - 0.54 and 0.01 - 0.92 ppm (wet weight)
were recorded in edible muscles tissues of crustacean and cephalopods species, respectively. Concentrations
exceededthe prescribed legal limitsof Egyptian Organization Standardization and Quality Control (E.O.S.Q.C)
and that stipulated by the European Commission (0.5 mg /kg [wet weight]) were observed in 32.50% of fish
samples, 2.50% of crustaceans samples and 22.50% of cephalopods samples. Mercury was the only element
showing a significant correlation with the size of the specimens’ .The highest mean levels of cadmium were
recorded in crab (0.938±0.097, ppm, wet weight) and squid (0.897±0.278,ppm wet weight) in particular and
to a lesser extent in cuttlefish and shrimp. No fish samples showed cadmium concentration exceeding the peak
permitted values of 0.1 ppm wet wt stipulated by E.O.S.Q. All samples in this study contained zinc within of
the general guideline limit for zinc in food of 50 mg/kg. The results were evaluated according to International
standards of WHO and FDA. Provisional tolerable weekly intakes or other internationally accepted standards
would also be used in this study to assess the relative safety of the Suez Canal fish supply.
Key words:
INTRODUCTION
levels of metals is a concern because chronic exposure to
heavy metals can cause health problems. Chronic
cadmium exposure has been linked to renal failure, bone
fragility and as a cancer–causing agent in humans[1,2,3,4].
Although zinc is an essential nutrient required for proper
growth and development, too little zinc can cause
problems, but too much zinc is also harmful to human
health[5]. Mercury (Hg) is one of the most important
pollutants both because of its effect on marine organisms
andit is potentially hazardous to humans. Methylmercury,
which is formed in aquatic sediments through the
bacterial methylation of organic mercury, is toxic
chemicals compound of mercury, in fact, nearly all of the
mercury in fish muscles occurs as Methylmercury[6].
Methylmercury affects the kidneys and also the central
nervous system, particularly during development, as it
crosses both the blood –brain barrier and placenta[7].
Suez Canal is artificial waterway of Egypt connecting
the Mediterranean Sea with the Gulf of Suez, an arm of
the Red Sea, and extending from Port Said to Suez
provinces. It is actually, the lonely canal linked between
the Mediterranean Sea and the Red Sea. The canal
provides a shortcut for ships operating between both
European and American ports and ports located in
southern Asia, eastern Africa, and Oceania . The northern
part of the Suez Canal at Port Said acts as fishing harbor
.Fishing is a field of considerable activity and seafood is
consumed by a large segment of the population in Port
Said. Fish is a commodity of potential public health
concern as it can be contaminated with a range of
environmentally persistent chemicals, including heavy
metals. The consumption of fish containing elevated
Corresponding Author: Zienab I. Soliman, Agriculture research center-Animal Health Research Institute, Dokki, Cairo,
Egypt-Port Said Lab.of Food Hygiene.
E. Mail: [email protected]
657
J. Appli. Sci. Res., 2(10): 657-663, 2006
In light of this concern and the pollution that is the
Suez Canal facing, questions have been raised about the
safety of eating fish and seafood from the Suez Canal
waters. Therefore, the present study was carried out to
measures the concentrations of heavy metals (mercury,
cadmium and zinc,) in common edible marine tissues of
different aquatic species caught in Suez Canal in order to
assess the seafood consumption safety. The relationships
between size (weight) and metal concentrations in the
tissues were investigated. The results were evaluated
according to International standards of WHO and FDA to
identify any potential public health risks and identify if
preventive public health strategies relating to dietary
exposure from metal contaminants in seafood are
required. Provisional tolerable weekly intakes or other
internationally accepted standards would also be used in
this study to assess the relative safety of the Suez Canal
fish supply.
Digestion of samples was carried out according to the
methods described by Al-Ghais[8]. Concentrations of
cadmium (Cd), zinc (Zn) and Mercury (Hg) were
measured with atomic absorption spectrophotometery.
The obtained data were statistically analyzed for
assessment of variation in metal concentrations among
small and large size individuals within each species .The
descriptive statistics (mean, maximum, minimum and
standard error) were recorded. Weekly intake
recommended by the joint Food and Agriculture
Organization/World Health Organization were included
and discussed in light of present findings.
RESULTS AND DISCUSSIONS
As shown in Table 2, the total mercury
concentrationsin the edible musclestissues offish species
were ranged from 0.18 to 1.17 ppm (wet weight) while
levels of 0.01 to 0.54 ppm (wet weight) and 0.01 to 0.92
ppm (wet weight) were recorded in edible musclestissues
of crustacean and cephalopods species, respectively.
Limits of total mercury level have been established in
various countries. The FDA has set a maximum total
mercury level of 1mg/kg (wet weight) in fish[9]. In Japan,
fish containing total mercury concentrations exceeding
the Japanese maximum permitted limit of 0.3 mg/kg
(wet weight) are considered unsuitable for human
consumption[10]. In Europe, the total mercury limit,
regulated by European Commission, is 0.5 mg/kg
(wet weight), except for some species for which it is
1.0 mg[11]. In Egypt, the total mercury limit, regulated by
Egyptian Organization Standardization and Quality
Control[12] is 0.5 ppm (wet weight) of fish. On this basis,
32.5% of fish samples, 2.5% of crustaceans samples and
22.5 % of cephalopods samp les had mercury
concentrations exceeded the prescribed legal limits of
E.O.S.Q.C. and that stipulated by the European
Commission (0.5 mg /kg [wet weight]). Total mercury
concentrations above the regulatory limits have been
observed for certain species occupying high trophic
positions[13] and in species that live on or close to sea
bed[14]. The high concentration of total mercury recorded
in some of examined samples may be attributed to high
sources of activities such as loading and unloading
operation at Port Said harbor and industrial effluents and
MATERIALS AND METHODS
Samples of Marine i.e. fish, crustaceans and
cephalopods, representing 6 species; consisting
commonly consumed species were assembled from the
site of harvesting at fishing harbor of the Suez Canal at
Port Said. Species targeted for collection and analysis
were, fish: mullet (Mugil cephalus) and Sardines (Sardina
pilchardus), crustacea: crab (Calinictus sapidus) and
shrimps (Metapenaeus nonoceras), and Molluscan
cephalopods: cuttlefish (Sepia spp.) and squid
(Loligo spp.). The analyses were carried out on 40
individual from each species. An attempt was made to
collect consistent size ranges within species. For each
species,two subdivisions within which individual samples
were collected as a function of their similar size were
formed from total number of specimens.
Laboratory Analysis: Samples collections were
delivered to Laboratory where they were sorted by
species, and size. Samples were then sorted into 12
groups, each consisting of 20 individuals. Samples
weightranges were recorded in Table (1). Muscles tissues
were removed from each group and preserved at –180C
until the analysis was carried out.
Table 1:
Weight ranges (gm) of seafood samples
Weight ranges (gm)
----------------------------------------------------Seafood samples
Small
Large
Mullet
100- 120
450-550
Sardine
50-60
80-100
Shrimp
9-12
40-50
Crab
100-120
225-250
Cuttlefish
130-142
330-345
Squid
90-100
120-135
Table 2: Overall percentage of total mercury in seafood samples by
groups (n480)
Total mercury (ppm)
Species
-----------------------------Samples exceed
group
Max
Min
0.5ppm: No (%)
fish
0.18
1.17
26 (32.50)
crustacea
0.01
0.54
2(2.50)
cephalopods
0.01
0.92
18(22.50)
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J. Appli. Sci. Res., 2(10): 657-663, 2006
Table 3: Total mercury concentrations (ppm (wet weight)) with respect to weight for different marine samples (n4 20)
Small
Large
Statistical
--------------------------------------------------------------------------------------------------------------------Seafood groups
Min
Max
Mean ±se
Min
Max
Mean ±se
Fish
Mullet
0.18
0.53
0.334±0.102
0.35
1.17
0.881±0.229
----------------------------------------------------------------------------------------------------------------------------------------------------------------Sardine
0.20
0.52
0.287±0.910
0.23
0.97
0.568±0.184
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Crustacean
Shrimp
0.01
0.09
0.042±0.230
0.06
0.54
0.256±0.151
----------------------------------------------------------------------------------------------------------------------------------------------------------------Crab
0.01
0.05
0.028±0.140
0.03
0.25
0.067±0.470
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Cephalopods
Cuttlefish
0.02
0.54
0.036±0.36
0.06
0.72
0.488±0.043
----------------------------------------------------------------------------------------------------------------------------------------------------------------Squid
0.01
0.51
0.126±0.321
0.02
0.92
0.418±0.321
significant correlation between size of samples and mercury concentrations at p<0.05 and p<0.01
Table 4: Estimated weekly seafood consumptions in a 70 Kg man
based on mean and maximum level of mercury found in
seafood samples, sufficient to reach the Hg Provisional
Tolerable Weekly Intake (PTWI): 5 μg.Kg-1.
Estimated weekly seafood intake (kg)
----------------------------------------------------------------Small
Large
------------------------------------------------Seafood samples Mean
Max
Mean
Max
Mullet
1.05
0.660
0.397
0.299
Sardine
1.22
0.673
0.616
0.361
Shrimp
8.33
3.89
1.37
0.648
Crab
12.5
7
5.22
1.40
Cuttlefish
9.724
0.648
0.717
0.486
Squid
2.78
0.686
0.837
0.380
The joint FAO/WHO Expert Committee on Food
Additive has established a provisional tolerable weekly
intake (PTWI) of 300 µg of total mercury (for 60 kg
person) of which no more than 200 µg should be present
as methylmercury[4]. These amount equivalents to 5 µg of
total mercury, per kg body weight and 3.3 methylmercury
per kg body weight. However, people in different
geographical area have different dietary pattern,
particularly with regard to seafood consumption. No
available data couldbe obtained for consumptions pattern
of seafood in Port Said. Therefore, the exposure of the
consumer of seafood to mercury has been assessed based
on the mean and highest mercury concentration found in
these species, which have been compared with Hg PTWI
of 5 µg/kg, Table (4). For adult (70 kg body weight), the
weakly consumptions of 299-397 gm of large size mullet,
or 361- 616 g of large size sardine or 380- 837 gm of
large size squid are sufficient to reach the PTWI (5 µg/kg
body weight) that may results in a risky daily intake of
mercuryif exposure is long term. However, to exceed the
PTWI would require consumption of 660 up to 1000 gm
or more of small size fish or 686- 2780 gm of small size
squid ,according to its mercuryconcentration so there was
an adequate margin of safety in consuming small size fish
and other seafood samples. On the other hand, all
crustaceans’ samples had a mean mercury levels falling
within range of 0.01-0.54 ppm (mg/kg). The dietary
exposure to mercury would not exceed the PTWI at level
up to 648 g for large size shrimp with concentrations of
0.54 ppm. Meanwhile, the risk is greater for women who
are pregnant or likely to become pregnant within the
followingyear because the effect of methylmercury on the
developingnervous system of the fetus[7]. The exceedance
of the PTWI is relatively greater for children as their food
intake is greater, on a bodyweight basis than that of adult.
Mercury has periodically raised concern. Fish
consumption is the only significant source of methyl
mercury in the public [20]. The earliest clinical signs and
symptoms of methylmercury poisoning are diffuse
paresthesias in the hands, in feet, and around the mouth.
Increased exposure may result in ataxia, constriction of
domestic drainage of Port Said city. Moreover, mercury
is being used as antifouling agent in marine paints. Thus,
ships waiting could add heavy contamination source at
Port Said. In this respect, El- Moselhy et al. [15] studied the
distribution of mercury in water along the Suez Canal
they reported that the worst affected regions in the Suez
Canal are Port Said (Hg, 42.77 ng/l). Table (3) provides
summary of the mean total mercury concentration found
in edible muscle tissues of selected samples with respect
to size (weight). Among the examined samples, the
highest total mercuryconcentrations were recorded in fish
sampleswhile the lowestvalues were found in shrimp and
crab. The variation in total mercury concentration among
different species could be explained by there different
migratory and feeding habits as well as different
metabolic and excretion rates, furthermore they hold
different position in the marine food. Other author[16,17]
reportedsimilar observations.Moreover, the total mercury
content of the examined samples increase with increasing
size of the specimen, Levels up to 1.17 ppm have been
found in large mullet in some samples, which is
considerably above the maximum permissible level
(0.5 ppm) for edible tissues of fish. Similar finding have
shown by other authors for other marine organism
(18,19). Older (larger) fish within a species may be more
contaminated because they have had more time to
ac cu mu la te co nt am in an ts in th ei r bo di es .
(Biomagnifications of mercury through the food chain).
659
J. Appli. Sci. Res., 2(10): 657-663, 2006
Table 5: Cadmium concentrations (ppm) wet weight with respect to weight ranges for different marine samples (n4 20).
Small
Large
Statistical
---------------------------------------------------------------------------------------------------------------------Seafood groups
Min
Max
Mean ±se
Min
Max
Mean ±se
Fish
Mullet
0.01
0.03
0.023±0.010
0.01
0.04
0.030±0.010
---------------------------------------------------------------------------------------------------------------------------------------------------------------Sardine
0.02
0.04
0.028±0.012
0.03
0.05
0.031±0.014
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Crustacean
Shrimp
0.39
1.51
0.727±0.286
0.43
1.53
0.860±0.308
---------------------------------------------------------------------------------------------------------------------------------------------------------------Crab
0.31
1.46
0.844±0.289
0.48
1.53
0.938±0.097
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Cephalopods
Cuttlefish
0.27
1.12
0.769±0.256
0.38
1.19
0.865±0.264
---------------------------------------------------------------------------------------------------------------------------------------------------------------Squid
0.49
1.05
0.755±0.202
0.48
1.17
0.897±0.278
Non significant correlation between size of samples and cadmium concentration.
Table 6: Estimated weekly seafood consumption in a 70 Kg man,
based on mean and maximum level of cadmium found in
seafood samples sufficient to reach the Cd Provisional
Tolerable Weekly Intake (PTWI): 7 μg.Kg-1.
Estimated weekly seafood intake (kg)
---------------------------------------------------------------Small
Large
--------------------------------------------------Seafood samples Mean
Max
Mean
Max
Mullet
21.30
16.34
16.34
12.25
Sardine
17.50
12.25
15.81
9.80
Shrimp
0.674
0.325
0.570
0.320
Crab
0.522
0.336
0.581
0.320
Cuttlefish
0.637
0.438
0.566
0.412
Squid
0.650
0.467
0.546
0.419
all crustacean and molluscan cephalopods samples
analyzed were below that recommended by several
agencies and organizations. Crustacean mainly live and
feed on sea bottom where deposit accumulate due to
runoff from shore. In this respect, Overnell, [26] reported
that cadmium levels in edible crab(Cancer pagurus) may
be as high as 30–50 ppm. Moreover, Juresa and Blanusa[27]
reported that cadmium level were almost 10 times higher
in shellfish than in finfish. .
The World Health Organization/Food and
Agricultural Organization[28] has established a provisional
tolerable weekly intake (PTWI) of 490 µg of cadmium
for 70 kg person. This amount equivalent to 7 μg Cd per
kg body weight/ week. The exposure of the consumer of
crustacean and cuttlefish to cadmium has been assessed
by the Cd concentrations found in these species, which
have been compared with Cd PTWI of 7 µg/kg,
Table (6). The weakly consumption of 320-674 gm of
shrimp,or 320- 581 g crab, or 412-637 g of cuttlefish may
sufficient to reach the PTWI. The data provided in this
study not taking other sources of dietary cadmium into
account. However apparent exposure may not reflect a
consistent weakly intake of this magnitude, as individuals
whoconsume crustacean and cephalopods consume them
sporadically. On the contrary, the exposure of the
consumer of fish to cadmium was low for all fish samples
and not considered to be of concern. However, because
the bodyhas no mechanism for the excretion of cadmium,
cadmiumaccumulatesin tissues; the half-lifeof cadmium
in kidney cortex is 10–30 years[29]. Chronic exposure to
low-level Cd has been associated with a number of
pathologies, such as end-stage renal failure, early onset of
diabetic renal complications, osteoporosis, deranged
blood pressure regulation, and increased cancer
risk[30,31,32].
With regarding to zinc, the present results in
Table (7) pointed out that all samples in this studycontained zinc within of the general guideline limit for
zinc in food of 50 mg/kg (ppm)[33]. higher concentrations
of zinc were seen in cephalopods and crustacean than in
the visual field, blurred speech and hearing difficulties.
With severe poisoning, patients may develop blindness
and general physical and mental debilitation [21]. The
lowest mercury levels associated with the onset of
clinical sign in adults were reported to be 50 µg/g in hair
and 200 µg/L in whole blood this level corresponds to a
long-term daily intake of 3 to 7 µg kg of body in form of
methylmercury[22].
Level of cadmium in edible tissues of fish and other
marine organisms’ samples were recorded in Table (5).
The highest mean levels of cadmium were recorded
in crab (0.938±0.097, ppm, wet weight) and squid
(0.897±0.278, ppm wet weight) in particular and to a
lesser extent in shrimp (0.860±0.308, ppm wet weight).
Concentrationof cadmium in tissues of mullet and sardine
samples were found to be safe for human consumption,
there was no fish samples showed cadmiumconcentration
exceeding permissible limits stipulated by the European
communities[23] of 0.05mg Cd/kg. However, the peak
permittedvalues stipulated by E.O.S.Q (12) is 0.1 ppm cd
wet weight. The European Community has setting
maximum limits (MLs) for Cd in bivalve mollusks at 1
mg/kg wet weight (1 ppm), and Australia, New Zealand,
and Hong Kong have a setting (MLs) for Cd in mollusks
of 2 ppm[24]. The FDA action level for cadmium in
crustacean seafood is 3 ppm and 4 ppm for Molluscan
Shellfish[25]. On this basis, the concentrations cadmium in
660
J. Appli. Sci. Res., 2(10): 657-663, 2006
Table 7: Zinc concentrations (ppm) wet weight with respect to weight ranges for different marine samples (n4 20).
Small
Large
Statistical
-------------------------------------------------------------------------------------------------------------------Seafood groups
Min
Max
Mean ±se
Min
Max
Mean ±se
Fish
Mullet
6.45
8.15
7.934±0.763
6.39
9.15
8.397±0.819
---------------------------------------------------------------------------------------------------------------------------------------------------------------Sardine
6.15
10.30
8.526±0.932
8.15
10.37
8.932±0.614
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Crustacean
Shrimp
12.17
17.05
15.984±1.617
12.80
19.20
17.360±1.052
---------------------------------------------------------------------------------------------------------------------------------------------------------------Crab
28.48
30.53
29.912±1.617
30.00
33.45
31.012±1.805
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Cephalopods
Cuttlefish
31.35
42.87
36.301±9.172
32.10
45.01
40.237±7.820
---------------------------------------------------------------------------------------------------------------------------------------------------------------Squid
36.87
43.00
40.451±2.207
37.15
45.17
41.740±2.773
Non significant correlation between size of samples and zinc concentration.
Table 8: Estimated daily seafood consumption in a 70 Kg man, based
on mean and maximum level of zinc found in seafood samples
sufficient to reach the zn Provisional Maximum Tolerable
Daily Intakes (PMTDIs): 70 mg/day
Estimated daily seafood intake (kg)
---------------------------------------------------------------Small
Large
-------------------------------------------------Seafood samples Mean
Max
Mean
Max
Mullet
8.82
8.59
8.34
7.65
Sardine
8.21
6.80
7.84
6.75
Shrimp
4.38
4.11
4.03
3.65
Crab
2.34
2.29
2.26
2.09
Cuttlefish
1.93
1.63
1.74
1.56
Squid
1.73
1.63
1.68
1.55
Harmful effects generally begin at levels 10-15 times
higher than the amount needed for good health. Large
doses taken by mouth even for a short time can cause
stomach cramps, nausea, and vomiting. Taken longer, it
can cause anemia and decrease the levels of good
cholesterol[39].
In conclusion, analytical data obtained from this
study shows that, in general, total mercury contaminants
were higher in fish than crustacean and cephalopods
meanwhile, tissues zinc and cadmium showed the
opposite. The groups at risk from mercury or other metal
poisoning are mostly pregnant women, very young
children, and those with weakened immune systems.
Moreover, People who eat large quantities of seafood,
such as professional fishers and their families should be
concerned. However, in general, people should choose
smaller fish or other seafood consistent; within a species
since theymay have lower contaminant levels also people
should eat a diversity of seafood to avoid consuming
unhealthy quantities of heavy metals. There is a need to
establish the necessary guidelines to the community
especially to high-risk groups such as pregnant women
and children.
fish with values for individual species in general in
agreement with literature values[34]. Therefore, the zinc
concentrations found in the present study are not of
concern. The Joint FAO/WHO Expert Committee on
Food Additives[35] established a provisional tolerable
weekly intake (PTWI) for zinc of 7000 µg/week / kg .The
ProvisionalMaximum Tolerable Daily Intakes (PMTDIs)
set by the Joint Expert Committee on Food Additives of
the Food and Agriculture Organization of the United
Nations and the World Health Organization (JECFA)[36]
for zinc is 1.0 mg/kg bodyweight/day (equivalent to
70 mg/day for a 70 kg adult), The dietary intakes of
seafood estimated from the present studies to exceed the
PMTDIs would require consumption of about 1550 gm or
more / day of large size squid (with level of 45.17 ppm
wet weight) , below these dietary intakes of any tested
seafood samples not represent any known risk to health.
Zinc is an essential trace element in our diet that is
required for the synthesis of DNA, RNA, and proteinand
thus for cell division[37]. The zinc-cadmium ratio is very
important, as cadmium toxicity and storage are greatly
increased with zinc deficiency. One illustration of the
importance of the zinc-cadmium relationship is that the
effects of cadmium on several biological systems,
including the formation of tumors, can be suppressed by
the simultaneous injection of zinc[38]. Too little zinc can
cause problems, but too much zinc is also harmful.
REFERENCES
1. Hellstrom, L., C.G. Elinder, B. Dahlberg,
M. Lundberg, L. Jarup, B. Persson, et al. 2001.
Cadmium and end-stage renal disease. Am J Kidney
Dis., [PubMed] [Full Text] 38: 1001-1008.
2. Staessen, J.A., H. Roels,
D. Emelianov,
T. Kuznetsova, L. Thijs and J. Vangronsveld, 1999.
Environmental expo sure to cadmium, forearm bone
density, and risk of fracture: prospective population
study. Lancet, 353: 1140-1144. NPRESS
3. Honda, R., K. Tawara, M. Nishijo, H. Nakagawa,
K. Tanabe andS. Saito, 2003.Cadmium exposure and
trace elements in human breast milk. Toxicology,
186: 255-259. [PubMed] [Full Text]
661
J. Appli. Sci. Res., 2(10): 657-663, 2006
4. WHO, 1993. Evaluation of Certain Food Additives
and Contaminants (Forty-first Report of the Joint
FAO/WHO Expert Committee on Food Additives).
WHO Technical Report Series No. 837. Geneva:
World Health Organization.
5. Agency for Toxic Substances and Disease
Registry, 2004. Agency for Toxic Substances
and Disease Registry, Division of Toxicology,
Clifton Road, NE, Atlanta, GA, available at
http://www.atsdr.cdc.gov/toxprofiles.
6. Joiris, C.R., L. Holsbeek, and N.L. Moaatemri, 1999.
Total and methylmercuryin sardines Sardinella aurita
and Sardina pilchardus from Tunisia. Mar. Pollut.
Bull., 38: 188-192.
7. clarkson, T.W., 2002. The three modern faces of
mercury . Environ. Health Perspect., 110: 11-23.
8. Al-Ghais, S.M., 1995. Heavy metal concentrations in
the tissues of Sparns seba from the United Arab
Emirate. Bull. Environ. Contam. Toxicol., 55: 581.
9. U.S. Food and Drug Administration, 2001. An
Important Message for Pregnant Women and
Women Who May Become Pregnant About the
Ris ks of Mercury in Fish, Jan, 2001.
www.fda.gov/bbs/topics/ANSWERS/2001/advisory.
html.
10. Dickman, M.D. and K.M.C. Leung, 1998 . Mercury
and organochlorine exposure from fish consumption
in Hong Kong. Chemosphere, 37: 991-101.
11. Anonymous, 16 June 1994. European Commission
Decision 93/351 of 19 May 1993. Off J. European.
Communities L.144.
12. Egyption Organization for Standardization and
Quality Control (E.O.S.Q.C), 1993. Maximum
residue limits for heavy metals in food " Ministry of
Industry" No.2360/ 1993 pp: 5 Cairo –Egypt.
13. Storelli, M.M. and G.O. Marcotrigiano, 2001. Total
mercury levels in muscles tissue of swordfish
(Xiphias gladius) and bluefintuna (Thunnus thynnus)
from the Mediterranean Sea. J. Food Prot.,
64: 1058-1061.
14. Storelli, M.M., R. Giacominelli Stuffler and
G.O. Marcotrigiano, 1998. Total mercury in muscle
of benthic and pelagic fish from the South Adriatic
Sea (Italy). Food Addit. Contam., 15: 876-883.
15. El-Moselhy, K.M., M.A. Hamed, and H. AbdelAzim, 1998. Distribution of mercury and tin
along the Suez Canal. J. Egypt. Ger. Soc. Zool.,
27: 33-42.
16. Storelli, M.M., R. Giacominelli Stuffler, A. Storelli,
and G.O. Marcotrigiano, 2003. Total mercury and
methylmercury content in edible fish from the
Mediterranean Sea. J. Food Protec., 66: 300-303.
17. Naqvi, I.I., S. Mohiuddin, M.K. Rafi, M.A. Farrukh,
I. Zehra and N. Siraj, 2003. Analysis of mercury in
seafood by cold vapor atomic absorption
spectroscopy. Pak. J. Biol. Sci., 6: 2010-2012.
18. Monterio, L.R., and H.D. Lopes, 1990. Mercury
content of swordfish, Xiphias glaudius, in
relation to length, weight, age and sex. Mar. Pollut.,
21: 293-296.
19. Licata, P., D. Trombetta, M. Cristani., C. Naccari,
D. Martino, M. Calo and F. Naccari, 2005. Heavy
metals in liver and muscles of bluefin tuna (Thunnus
thynnus) caught in the Straits of Messina (Sicily,
Italy). Environ. Monit. Assess., 107: 239-248.
20. Rice, G., J. Swartout, K. Mahaffey and R. Schoeny,
2000. Oral reference dose (RfD) for methylmercury.
Drug Chem. Toxicol.,23(1):41–54. [PubMed] [Full
Text].
21. World Health Organization, 1967. Environmental
heath criteria. 1. Mercury. World Health
Organization , Geneva.
22. World Health Organization, 2000. Safety Evaluation
of Certain Food Additives and Contaminants . WHO
Food Additives Series 44.
23. Commission of the European Communities, 2001.
Commission Regulation (EC) No. 221/2002 of 6
February 2002 amending regulation (EC) No.
466/2002 setting maximum levels for certain
contaminants in foodstuffs. Official Journal of the
European Communities, Brussels, 6 February 2002.
24. Codex Alimentarius Commission, 2000. Report of
the 32nd Session of the Codex Committee on Food
Additives and Contaminants. ALINORM 01/12A,
Rome: Codex Alimentarius Commission.
25. Food and Drug Administration, 1993. Guidance
Document for Cadmium in Shellfish. U.S.
Department of Health and Human Services, Public
Health Service, Office of Seafood (HFS-416), 200 C
Street, SW, Washington, D.C. 20204. 44 pages.
26. Overnell, J., 1996. Occurrence of cadmium in crabs
(Cancer pagurus) and the isolation and properties of
cadmium-metallothionein. Environ. HealthPerspect.,
65: 101-105.
27. Juresa, D. and M. Blanusa, 2003. Mercury, arsenic
and cadmium in fish and shellfish from the Adriatic
Sea. Food Addit. Contam. Mar., 20: 241-246.
28. WHO, 1989. Evaluation of Certain Food Additives
and Contaminants (Thirty-third Report of the Joint
FAO/WHO Expert Committee on Food Additives).
WHO Technical Report Series No. 776. Geneva:
World Health Organization.
662
J. Appli. Sci. Res., 2(10): 657-663, 2006
29. Jarup, L., M. Berglund, C. Elinder, G. Nordberg and
M. Vahter, 1998. Health effects of cadmium
exposure—a review of literature and a risk estimate.
Scand J Work Environ Health, 24(suppl 1): 1–52.
[PubMed]
30. Nakagawa, H. and M. Nishijo, 1996. Environmental
cadmium exposure, hypertension and cardiovascular
risk. J Cardiovasc. Risk, 3: 11-17. [PubMed]
31. Satarug, S., M.R. Haswell-Elkins and M.R. Moore,
2000. Safe levels of cadmiumintake to prevent renal
toxicity in human subjects. Br J Nutr., 84: 791-802.
32. Holland, B., A.A. Welch, I.D. Unwin, D.H. Buss,
A.A. Paul and D.A.T. Southgate, 1991. The
Composition of Foods. Fifth Revised and Extended
Edition. The Royal Society of Chemistry and
Ministry of Agriculture, Fisheries and Food.
33. MAFF, 1995. Monitoring and surveillance of nonradioactive contaminants in the aquatic environment
and activities regulating the disposal of wastes at sea,
1993. Aquatic Environment Monitoring Report No.
44. Directorate of Fisheries Research, Lowestoft.
34. Ministry of Agriculture, Fisheries and Food ,1997.
Total Diet Study: Metals and Other Elements. Food
Surveillance Information Sheet No. 131.
35. Joint FAO/WHO Expert Committee on Food
Additives, 2004. Summary of EvaluationsPerformed
by the Joint FAO/WHO Expert Committee on Food
Additives (JECFA 1956–2003), (First through sixtyfirst meetings). Food andAgriculture Organization of
the United Nations and the World Health
Organization, ILSI Press International Life Sciences
Institute,
36. World Health Organization,1982. Evaluation of
Certain Food Additives and Contaminants. Twentysixth Report of the Joint FAO/WHO Expert
Committee on Food Additives. WHO Technical
Report Series No. 683. World Health Organization,
Geneva. Washington, DC.
37. Prasad,A. S., 1983. The role of zinc in
gastrointestinal and liver disease.Clin. Gastroenterol,
12: 713-741.
38. Abshire, M.K., G.S. Buzard, N. Shiraishi,
M.P. W``aakes, 1996. Induction of c-myc and c-jun
proto-oncogene expression in rat L6 myoblasts by
cadmium is inhibited by zinc preinduction of the
metallothionein gene. J. Toxicol. Environ. Health,
48: 359-377.
39. Agency for Toxic Substances and Disease Registry
(ATSDR), 2005. Toxicological Profile for Zinc
(Update). Atlanta, GA: U.S. Department of Public
Health and Human Services, Public Health Service.
663