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Residues of DDTs, PAHs and Some HeavyMetals in Fish (Tilapia) Collected fromHong Kong and Mainland ChinaKAI-YIP KONG a , KWAI-CHUNG CHEUNG a , CHRIS-KONG-CHU WONG a

& MING-HUNG WONG aa Croucher Institute for Environmental Sciences, and Department ofBiology , Hong Kong Baptist University , Hong Kong, PR ChinaPublished online: 06 Feb 2007.

To cite this article: KAI-YIP KONG , KWAI-CHUNG CHEUNG , CHRIS-KONG-CHU WONG & MING-HUNGWONG (2005) Residues of DDTs, PAHs and Some Heavy Metals in Fish (Tilapia) Collected from HongKong and Mainland China, Journal of Environmental Science and Health, Part A: Toxic/HazardousSubstances and Environmental Engineering, 40:11, 2105-2115, DOI: 10.1080/10934520500232738

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Journal of Environmental Science and Health, 40:2105–2115, 2005Copyright C© Taylor & Francis Inc.ISSN: 1093-4529 (Print); 1532-4117 (Online)DOI: 10.1080/10934520500232738

Residues of DDTs, PAHs andSome Heavy Metals in Fish(Tilapia) Collected from HongKong and Mainland China

Kai-Yip Kong, Kwai-Chung Cheung, Chris-Kong-Chu Wong,and Ming-Hung WongCroucher Institute for Environmental Sciences, and Department of Biology, Hong KongBaptist University, Hong Kong, PR China

Most of the freshwater fish consumed in Hong Kong is imported from the southern partof China, although Hong Kong also produces a small amount of freshwater fish. Themajor aim of the present study was to conduct a health risk assessment of fish producedfrom the mainland (purchased from four local markets in Hong Kong) compared withthose produced from Hong Kong fishponds. Thirty tilapia fish (Tilapia mossambicus)were collected from the fishponds at Tam Kon Chau, Nam Sang Wai, and Mai Po NatureReserve (Northwest New Territories of Hong Kong), and four local markets (Tai Po, LokFu, Sham Shui Po and Cheung Sha Wan wholesale markets) in Hong Kong for the analy-ses of PAHs, DDTs and three toxic metals (cadmium, chromium, lead). Tilapia purchasedfrom the markets (with fish supplied from the mainland) showed higher concentrationsof DDTs and PAHs than those collected from Hong Kong fishponds, confirmed that thefishponds in the mainland are more polluted due to the rapid socioeconomic growth inthe region during the past 20 years. The tilapia were heavily polluted by Pb, with thehighest level (3519 ng g−1 wet wt.) exceeded the EUROPA guideline (400 ng g−1 wetwt.) 8 times, and Cr with 36% of the samples exceeded the China guideline of 500 ngg−1 wet wt. for human consumption. The coastal Chinese populations which consumelarger quantities of fish may be at risk. Tilapia collected from the Mai Po Nature Reservecontained the highest level of Cr, which may also impose adverse effects on water birds,including the endangered species that frequently visiting the site for food and shelter.

Key Words: Hong Kong; Mai Po Marshes; POPs; Polycyclic aromatic hydrocarbons; DDTs;Heavy metals; Freshwater fish; Tilapia.

Received November 29, 2004.Address correspondence to Ming-Hung Wong, Croucher Institute for EnvironmentalSciences, and Department of Biology, Hong Kong Baptist University, Hong Kong, PRChina; E-mail: mhwong@hkbu.edu.hkThis paper was presented at “The 2nd Asian International Conference on Ecotoxicologyand Environmental Safety” (SECOTOX 2004), Songkla, Thailand, 26–29 September2004.

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INTRODUCTION

The Pearl River (Zhujiang) is the largest river system in southern China withapproximately 2,200 km long, discharges into the South China Sea through anextensive deltaic area to the west of Hong Kong. The Pearl River Delta (PRD)has become a very important place for agricultural, commercial and industrialdevelopments due to its favourable physical characteristics (flat, fertile land,abundance of freshwater). However, the environmental quality has deterioratedwith the rapid economic growth. The waters have been significantly contami-nated by POPs and heavy metals and the food quality and food safety issue hasbecome an environmental concern.[1]

Recent studies on the levels of polycyclic aromatic hydrocarbons (PAHs)and dichloro-diphenyl-trichloroethane (DDT) in fishponds sediments and fishcollected from the Pearl River Delta revealed that elevated levels of PAHs andDDTs were detected in the pond sediment and fish. More than 30% of the fishsamples containing total DDTs exceeded the guideline values recommended byUS EPA for human consumption.[2] The findings indicated recent applicationof DDT into fishponds, although it was officially banned in 1983 in China. Thelevels of DDTs accumulation in human milk were significantly correlated withthe frequency of fish consumption.[3] Most of the freshwater fish consumed inHong Kong is imported from the southern part of the mainland China (PearlRiver Delta), although Hong Kong pond fish farms also produces a small amount(6%) of freshwater fish.[4] The high level of DDTs contamination in food fish mayimpose a serve health risk on local consumer.

Tilapia (Tilapia mossambicus) was chosen for this study because of its eco-nomic importance and ubiquitous distribution. Most fishponds would practicepolyculture of carps mixed with tilapia. It was introduced into Hong Kong as animportant food fish in 1950s. It is omnivorous with a diversified diet character.[5]

Due to its fast growth, successful spawning, and high resistance to diseases,tilapia is now widely distributed in fishponds, reservoirs, and rivers in HongKong.[6]

The major aim of the present study was to conduct a health risk assessmentof fish produced from the mainland China, compared with those cultivated inHong Kong fishponds. The levels of DDTs, PAHs, and three toxic metals (Cd,Cr, Pb) in tilapia available in the local markets (where fish are imported fromthe Pearl River Delta) and local fishponds (Hong Kong) were investigated inorder to estimate the potential health hazards of consuming these fish.

MATERIALS AND METHODS

Sample CollectionThirty tilapia (Tilapia mossambicus) with an average size of 26 ± 3 cm and

an average weight of 349 ± 114 g were collected from January through June

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Heavy Metal Residues from Fish in Hong Kong and Mainland China 2107

2003 from two fishponds at Tam Kon Chau and Nam Sang Wai (Northwest NewTerritories of Hong Kong), the abandoned fish and shrimp cultivation ponds(local name gei wais) at Mai Po Nature Reserve and four local markets (Tai Po,Lok Fu, Sham Shui Po, and Cheung Sha Wan wholesale markets) in Hong Kongwith fish imported from southern part of China. The nature reserve at Mai PoMarshes was designated as a RAMSAR Site in 1995. Wintering birds, such asherons, egrets, and the endangered Black-faced Spoonbill (Platalea minor), areattracted into the area and feed on fish and shrimps.[7]

Analysis of PAHs and DDTs in TilapiaThe muscle tissues of each tilapia were used for analyses. The fish flesh

was separated, freeze-dried, and homogenized prior to subsequent analyses.The moisture content was determined according to weight loss before and af-ter freeze-drying. Extraction of PAHs and DDTs from fish muscle tissue wasperformed according to the EPA Standard Method 3540C.[8] About 3 g of fishmuscle were used for soxhlet extraction. Weighed samples was transferred intoa soxhlet apparatus and extracted by 80 ml acetone and dichloromethane mix-ture (1:1, v:v) in a 65◦C water bath for 18 h. The proper cleanup procedures wereestablished for analysis of PAHs and DDTs in these samples. A series of chro-matographic columns were applied for sample cleanup such as florisil cleanup(EPA Standard Method 3620B)[9] and gel-permeation cleanup (EPA StandardMethod 3640A)[10] to remove the residual lipid in tissue extracts.

The analytical methods were based on GC-MS detection (EPA Stan-dard Method 8270C).[11] The 16 target PAHs compounds investigated inthis study included naphthalene, acenaphthylene, acenaphthene, fluorene,phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, chrysene,benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene, dibenz[a,h]anthracene and benzo[g,h,i]perylene. The 3 target DDTscompounds included p,p′-DDE, p,p′-DDD and p,p′-DDT. Total PAHs concentra-tion was calculated by summing the concentration of the 16 parent PAHs. DDTswas the sum of p,p′-DDE, p,p′-DDD and p,p′-DDT. The reporting limits of PAHsand DDTs were calculated according to the methods stated by the StandardMethods.[12] The detection limits for all species of PAHs were rounded up to20 ng g−1, while those of DDTs were 1–10 ng g−1 (p,p′-DDE: 1 ng g−1; p,p′-DDD: 2 ng g−1; p,p′-DDT: 10 ng g−1).

Analysis of Heavy MetalsCadmium, Cr and Pb in fish muscle were determined according to the EPA

Standard Method 3050B with slight modifications.[13] Then, 0.5 g of fish mus-cle samples were predigested with 8 ml conc. nitric acid at 25◦C overnight, andthen at 110◦C until the liquor was clear and no brown fumes were emitted. Af-ter the samples were cooled, 2 ml of 30% hydrogenperoxide (H2O2) was added.

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2108 Kong et al.

The samples were then heated at 110◦C and 30% H2O2 was added continuouslyin 1-ml aliquots with heating until the effervescence was minimal or until thegeneral sample appearance was unchanged. The digestate was boiled continu-ously until the volume had been reduced to approximately 5 ml. After cooling,the digestate was filtered through an Advantec 5C filter paper and diluted into50 ml in a volumetric flask. They were stored in acid-rinsed polyethylene bottlesat 4◦C prior to analysis. The heavy metal concentrations (Cd, Cr and Pb) weredetermined using a graphite furnace atomic absorption spectrometry (GFAA),the instrument detection limits for Cd and Cr were 1 ng g−1, while Pb was5 ng g−1.

There were triplicates for each sample. A standard reference material(TORT-2 lobster hepatopancreas reference material for trace metals, NationalResearch Council of Canada) was used to verify the accuracy of metal deter-mination. The recovery rates for all target heavy metals in the standard werewithin 85 ± 10%.

Statistical AnalysisThe one-way ANOVA test followed by Duncan’s Multiple Range Test in

the SPSS 11 software program were used to evaluate significant difference (atp < 0.05), in terms of contaminants (DDTs, PAHs, and heavy metals) concen-trations among fish samples from different regions.

RESULTS

PAHs and DDTsThe levels of PAHs and DDTs in muscle tissues ranged from 15.1 to 92.5

with an average of 63.3 ng g−1 wet wt. and 0.53 to 31.7 with an average of10.1 ng g−1 respectively (Table 1). Naphthalene, phenanthrene, and DDE werethe dominant species commonly found in muscle. Table 2 compares the levelsof PAHs and DDTs in tilapia collected from three major sources including mar-kets (fish imported from southern part of China), fishponds in Hong Kong andMai Po Nature Reserve. Tilapia purchased from the mainland showed signifi-cantly (p < 0.05) higher levels of DDTs, PAHs and potency-weighted total PAHsconcentration than tilapia collected from Hong Kong fishponds and the naturereserve.

Heavy Metal AnalysesAmong the three metals tested, Pb was the highest (507–3519 ng g−1

wet wt.) followed by Cr (undetectable–884 ng g−1 wet wt.) and then Cd(undetectable–298 ng g−1 wet wt.) in the tilapia muscle tissue (Table 1). Table 2

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Heavy Metal Residues from Fish in Hong Kong and Mainland China 2109

Table 1: The concentrations (ng g−1 wet wt.) of PAHs, DDTs and heavy metals inmuscle of tilapia and the corresponding guideline values.

Guidelinevalues/maximum

Concentrations permittedChemicals (ng g−1) concentration Reference countries

Total PAHs 15.1–92.5Potency-weighted

total PAHs#<0.01–0.15 0.67 USA[14]

Total DDTs 0.53–31.7 14.4 USA[14]

Cd <0.01–298 100200

2,000

EUROPA[15]

Australia, NewZealand[16]

Hong Kong[17]

Cr <0.01–884 5001,000

China[18]

Hong Kong[17]

Pb 507–3519 400500

6,000∗

EUROPA[15]

Australia, NewZealand[16]

Hong Kong[17]

# Potency-weighted concentration was calculated for comparison with the recommendedscreening guideline for benzo[a]pyrene based on guidance for quantitative risk assessmentof PAHs.[19,20]∗The maximum permitted level is for all food in solid form.

further compares the levels of Cd, Cr, and Pb in tilapia collected from differentsources. In general, tilapia collected from the nature reserve had lower meanlevels of all the three metals except Cr in muscle than those collected from theother two sources.

DISCUSSION

Accumulation of PAHs and DDTs in TilapiaRelatively higher levels of PAHs (15.1–92.5 ng g−1 wet wt.) were detected

in tilpia muscle when compared to our previous study (1.91–62.1 ng g−1 wetwt.).[2] The potency-weighted total PAHs concentrations in muscle were farbelow the guideline values (0.67 ng g−1 wet wt.) recommended by U.S. EPAfor human consumption.[13] On the contrary, 27% of tilapia showed that totalDDTs levels exceeded the guideline value of 14.4 ng g−1 wet wt. recommendedby U.S. EPA,[14] with the highest level in tilapia obtained from Sham Shui Pomarket (31.7 ng g−1 wet wt.) exceeded 2 times. According to the guideline,2 out of 5 samples collected from the nature reserve, and one fourth of tilapiapurchased from local markets and fishponds might pose health risks for humanconsumption.

Tilapia purchased from the markets (with fish supplied from the mainland)showed significantly higher levels of DDTs, PAHs and potency-weighted total

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Tab

le2:

The

co

nc

en

tra

tion

s(n

gg

−1w

et

wt.

±St

d.

Erro

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fPA

Hs,

DD

Tsa

nd

he

avy

me

tals

inm

usc

leo

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iac

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dfr

om

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s.

Sour

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Tota

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talP

AH

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Hs

Cd

Cr

PbM

ark

ets

(11)

3.49

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14.6

6±

2.66

a76

.5±

3.64

a0.

11±

0.01

a33

.4±

26.6

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8±

94.5

ab

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±22

6a

Fish

po

nd

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4.59

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1.96

±1.

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6.55

±1.

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±5.

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0.01

ab

9.27

±4.

72a

223

±69

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2080

±17

8a

Ho

ng

Ko

ng

(14)

Ma

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ture

1.64

±0.

70b

6.84

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84a

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77±

2.72

ab

43.3

±6.

67b

0.04

±0.

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5.34

±2.

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527

±95

.0a

1430

±18

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Re

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9,20

]

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Heavy Metal Residues from Fish in Hong Kong and Mainland China 2111

PAHs than those from Hong Kong fishponds and the nature reserve (Table 2),indicating that the fishponds in the mainland China are more polluted byDDTs. The results were also in line with our previous findings that elevatedlevels of DDTs were detected in different fish species collected from the PearlRiver Delta, with a large amount of freshwater fish imported to Hong Kongdaily.[2]

Accumulation of Heavy Metals in TilapiaFish have different routes for possible excretion of heavy metals when

exposed to heavy metal contaminated environment; the most important oneis through the bile as liver is the main organ for the detoxification ofxenobiotics.[21,22] This was somewhat expected as most of the heavy metalsare accumulated in the liver and kidney, and low in muscle after ingestion.[23]

However, elevated levels of heavy metals were detected in tilapia muscles inthe present study.

The international guidelines on maximum permitted concentrations ofheavy metals in fish for human consumption are listed in Table 1. The aver-age person in Hong Kong consumes fish or shellfish four or more times a weekaveraging about 60 kg of fish per year, equal to 164.4 g day−1.[24] The guide-lines recommended by Hong Kong Special Administrative Region Governmentare very high when compared with other countries, they are not protectiveenough for Hong Kong population who consumes a larger quantity of fish everyday.[17] Therefore, the more stringent guidelines set by European Union[15] andChina[18] were used for risk assessment in the present study.

The muscle tissues were heavily polluted by Pb and Cr, but Cd levels werelow {far below the guidelines set by US EPA (491 ng g−1 wet wt.);[14] FoodStandards Australia New Zealand (200 ng g−1 wet wt.);[16] and EUROPA (100ng g−1 wet wt.)[15]}. Concentrations of Pb in all the muscle samples exceededthe EUROPA guideline of 400 ng g−1 wet wt. for human consumption,[15] withthe highest level (3519 ng g−1 wet wt.) exceeded the guideline value 8 times.Moreover, 36% of the muscle samples exceeded the Cr guideline of 500 ng g−1

wet wt.[18] According to these guidelines, all tilapia obtained from the markets,fishponds and gei wais are unsafe for human consumption.

Lead is one of the most ubiquitous toxic metal, it presents in aquatic and ter-restrial ecosystems at relatively low levels. However, anthropogenic emissionscontribute the majority to the elevated levels commonly observed. It tends toaccumulate in soils and sediments, where it can remain accessible to the foodchain and to human metabolism for many years.[25,26] Lead pollution in cities iswidely accepted as one of the major pollutants caused by vehicles emissions.[27]

Hong Kong Government introduced unleaded petrol (ULP) in 1991 and bannedthe supply, sale and dispensing of leaded petrol as well as any fuel additivescontaining Pb in 1999,[28] and the production of leaded petrol (LP) in China was

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2112 Kong et al.

banned in 2000.[29] However, LP might still be used in China. Lead is toxic toall aquatic biota and there is appreciable evidence showing the bioavailabilityof sediment-bound Pb to deposit feeding species,[30] and organisms (fish) thatutilize gill tissue as the major nutrient uptake route.[31] The fast developmentof the Pearl River Delta and the deteriorating environment might contributeto the high levels of Pb accumulated in the tilapia, a benthic fish which feedson sediment and bottom detritus.[32]

Cadmium and Cr are toxic metals and classified as human carcinogens.[33,34]

Both Cd and Cr can be dissolved in water and taken up by fish, plants and an-imals. Since Cd could stay in fish for a long period and build up from yearsof exposure to low levels, the relative low levels of Cd in the muscle of tilapiaindicated that the background levels of Cd in the environment from where thefish collected might be at a very low level. Fish would not normally accumu-late much Cr in their bodies from water;[35] the elevated Cr levels noted in themuscle might be due to the feeding mode of tilpia, consuming benthic organ-isms and detritus associated with the Cr contaminated sediments. The meanlevels of Pb and Cr detected in the present study were 4–5 times higher thana previous study with the same fish species collected from Mai Po.[36] Tilapiacollected from the nature reserve showed lowest levels of heavy metals amongall the samples examined, except Cr that showed an average value exceedingthe guideline of 500 ng g−1 wet wt. for human consumption[18] and signifi-cantly higher than that in fish collected from fishponds in Hong Kong. Thesediment in the nature reserve might be heavily polluted by Cr and which arereadily taken up by tilapia. This may impose adverse effects on water birds,including the endangered species that frequently visiting the site for food andshelter.

Risk Assessment of Fish ConsumptionBased on the guideline of US EPA for DDTs, the estimated maximum daily

intake of DDTs from fish is around 2.05 µg day−1 for a 70 kg person. The pro-visional tolerable daily intakes suggested by the FAO/WHO for Cd and Pb are70 µg day−1 and 245 µg day−1 for a 70 kg person.[37] And the recommended dailyamount indicated for Cr by the US National Research Council is about 60 µgday−1 for a 70 kg person.[38] According to the fish consumption rate of Hong Kongpopulation (164.4 g day−1) reported by Dickman and Leung in 1998,[24] Pb con-centrations in about 80% and Cr concentrations in more than 40% of the tilapiasamples would lead to exposure levels higher than the recommended daily in-take limits. Using the above tolerable intake levels, the maximum amount ofdaily fish (tilapia) intake was calculated (Table 3). The maximum fish con-sumption allowed is 65 g day−1 (limited by DDTs). This amount is lower thana typical serving size of 200 g. Therefore, it can be assumed that it may posehealth hazard to human who consume larger quantities of fish everyday.

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Heavy Metal Residues from Fish in Hong Kong and Mainland China 2113

Table 3: Calculated maximum daily intake of fish. Assuming body weight of 70 kg.

CalculatedHighest maximum

Guideline levels concentration in daily intake(ng kg−1 BW day−1) References tilapia (ng g−1) of fish (g)

DDTs 29.3 US EPA[14] 31.7 65Cd 1000 FAO/WHO[37] 298 235Cr 857 US National Research 884 68

Council[38]

Pb 3500 FAO/WHO[37] 3519 70

CONCLUSION

Bioaccumulation of the studied pollutants (PAHs, DDTs, Cd, Cr and Pb) hasbeen observed in fish collected from local markets and fishponds. The levelsof DDTs, Pb and Cr in tilapia purchased from local markets and fishpondsare likely to pose health hazards. Tilapia purchased from the markets (withfish supplied from the mainland) showed higher levels of DDTs, PAHs, andpotency-weighted total PAHs than those from Hong Kong fishponds and geiwais, confirmed that the fishponds in the mainland China are more polluteddue to the rapid socio-economic growth in the region. Tilapia from the naturereserve (Mai Po) showed the lowest levels of pollutants studied except Cr, whichmay impose adverse effects on water birds. The present results showed themaximum fish consumption allowed was 65 g day−1, which is far below thereporting fish consumption rate (164 g) of Hong Kong people, it may pose healthhazard to human who consume larger quantities of fish everyday. In orderto safeguard residents from consuming polluted fish, more extensive study ofPOPs and heavy metals accumulation in different fish species is recommendedso that a more complete picture concerning the health hazard of freshwater fishconsumption and the quality of fish from different sources can be obtained.

ACKNOWLEDGMENTS

The authors would like to thank Dr. Lew Young of WWF Hong Kong Mai PoNature Reserve, Mr. B.H.T. Poon and Mr. K.W. Chan of Hong Kong BaptistUniversity for their technical assistance. Financial support from the GroupResearch, Central Allocation (No. HKBU-2/00C), Reserach Grants Council ofthe University Grants Committee of Hong Kong is gratefully acknowledged.

REFERENCES

1. PRC Environment Yearbook Committee. China Environment Yearbook. China En-vironment Yearbook Committee Press, Beijing, 1990–1997.

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2114 Kong et al.

2. Kong, K.Y.; Cheung, K.C.; Wong, C.K.C.; Wong, M.H. The residual dynamics of poly-cyclic aromatic hydrocarbons and organochlorine pesticides in fishponds of the PearlRiver Delta, South China. Water Res. 2005, 39, 1831–1843.

3. Wong, C.K.C.; Leung, K.M.; Poon, B.H.T.; Lan, C.Y.; Wong, M.H. Organochlorinehydrocarbons in Human Breast milk collected in Hong Kong and Guangzhou. Arch.Environ. Contam. Toxicol. 2002, 43, 364–372.

4. AFCD (Agriculture, Fisheries and Conservation Department). Agriculture, Fisheriesand Conservation Department Annual Report 2001–2002. Government of Hong KongSpecial Administrative Region: PRC, 2003.

5. Man, S.H.; Hodgkiss, I.J. Hong Kong Freshwater Fishes. Urban Council: Hong Kong,1981.

6. Zhou, H.Y.; Cheung, R.Y.H.; Wong, M.H. Residues of organochlorines in sedimentsand tilapia collected from inland water systems of Hong Kong. Arch. Environ. Contam.Toxicol. 1999, 36, 424-431.

7. WWF Hong Kong. Mai Po. World Wildlife Fund, Hong Kong. Retrieved from theWorld Wide Web, 2000 〈http://www.wwf.org.hk/eng/maipo/index.html〉.8. U.S. Environmental Protection Agency. Method 3540C: Soxhlet Extraction. U.S. En-vironmental Protection Agency: Washington, DC, 1996.

9. U.S. Environmental Protection Agency. Method 3620B: Florisil Cleanup. U.S. Envi-ronmental Protection Agency: Washington, DC, 1996.

10. U.S. Environmental Protection Agency. Method 3640A: Gel-Permeation Cleanup.U.S. Environmental Protection Agency: Washington, DC, 1994.

11. U.S. Environmental Protection Agency. Method 8270C: Semivolatile Organic Com-pounds by Gas Chromatography/Mass Spectrometry (GC/MS). U.S. Environmental Pro-tection Agency: Washington, DC, 1996.

12. Clesceri, L.S.; Greenberg, A.E.; Eaton, A.D. Standard Methods for the Exami-nation of Water and Wastewater, 20th Edition. Amercian Public Health Association:Washington, DC, 1998.

13. U.S. Environmental Protection Agency. Method 3050B: Acid Digestion of Sediments,Sludges, and Soils. U.S. Environmental Protection Agency: Washington, DC, 1996.

14. U.S. Environmental Protection Agency. Guidance for Assessing Chemical Contam-inant, Data for Use in Fish Advisories, Vol. 1. Fish sampling and Analysis. 3rd ed. EPA823-R-95-007. Office of Water: Washington, DC, 2000.

15. EUROPA. Assessment of the dietary exposure to arsenic, cadmium, lead and mer-cury of the population of the EU Member States. Directorate-General Health and Con-sumer Protection: European Union, 2004.

16. FSANZ. Food Standards Code. Food Standards Australia New Zealand, Anstat PtyLtd, Australia, 2002.

17. Government of HKSAR. Part V (Food and Drugs) of the Public Health and Munic-ipal Services Ordinance (Cap. 132), Food Adulteration (Metallic Contamination) Regu-lations. Hong Kong Special Administrative Region: Hong Kong, 1989.

18. NEPA (National Environmental Protection Agency). China Environmental StateBulletin: 1996. Environ. Protect. 1997, 236, 2–5.

19. Nisbet, I.C.T.; LaGoy, P.K. Toxic equivalency factors (TEFs) for polycyclic aromatichydrocarbons (PAHs). Regul. Toxicol. Pharmacol. 1992, 16, 290–300.

20. U.S. Environmental Protection Agency. Provisional Guidance for Quantitative RiskAssessment of Polycyclic Aromatic Hydrocarbons. EPA/600/R-93/089. Environmental

Dow

nloa

ded

by [

McG

ill U

nive

rsity

Lib

rary

] at

23:

56 1

9 N

ovem

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2014

Heavy Metal Residues from Fish in Hong Kong and Mainland China 2115

Criteria and Assessment Office, Office of Health and Environmental Assessment:Cincinnati, OH, 1993.

21. Sorensen, E.M.B. Metal Poisoning in Fish. CRC Press: Boca Raton, FL, 1991.

22. Devaux, A.; Flammarion, P.; Bernardon, V.; Garric, J.; Monod, G. Monitoring ofthe chemical pollution of the River Rhone through measurement of DNA damage andcytochrome P4501A induction in Chub (Leuciscus cephalus). Marine Environ. Res. 1998,46, 257–262.

23. Badsha, K.S.; Goldspink, C.R. Preliminary observations on the heavy metal contentof four species of freshwater fish in N.W. England. J. Fish Biol. 1982, 21, 251–267.

24. Dickman, M.D.; Leung, K.M.C. Mercury and organochlorine exposure from fishconsumption in Hong Kong. Chemosphere 1998, 37, 991–1015.

25. Sauve, S.; McBride, M.B.; Hendershot, W.H. Speciation of lead in contaminatedsoils. Environ. Pollut. 1997, 98, 149–155.

26. ATSDR. Toxicological profile for lead on CD-ROM. Agency for Toxic Substancesand Disease Registry. U.S. Public Health Service: Washington, DC, 1999.

27. Yang, S.J.; Dong, J.Q.; Cheng, B.R. Characteristics of air particulate matter andtheir sources in urban and rural area of Beijing, China. J. Environ. Sci. (China) 2000,12, 402–409.

28. Environmental Protection Department. Press release. Retrieved from the WorldWide Web, 1999 〈http://www.epd.gov.hk/epd/english/news events/press/press 990205.html〉.29. SEPA (State Environmental Protection Administration of China). State Environ-mental Protection Administration of China, 2003.

30. Bryan, G.W; Langston, W.J. Bioavailability, accumulation and effects of heavy met-als in sediments with special reference to United Kingdom estuaries: a review. Environ.Pollut. 1992, 76, 89–131.

31. Sadiq, M. Toxic Metal Chemistry in Marine Environments. Marcel Dekker Inc.:New York, 1992.

32. Wong, M.H.; Hung, K.M.; Chiu, S.T. Sludge-growth algae for culturing aquaticorganisms. Part II. Sludge-growth algae as foods for aquatic organisms. Environ. Manag.1996, 20, 375–384.

33. IARC (International Agency for Research on Cancer). Beryllium, Cadmium, Mer-cury and Exposure in the Glass Manufacturing Industry, Vol. 58. IARC Scientific Publi-cations: Lyon, 1993.

34. ATSDR. Toxicological profile for chromium on CD-ROM. Agency for Toxic Sub-stances and Disease Registry. U.S. Public Health Service: Washington, DC, 2000.

35. ATSDR. Toxicological profile for cadmium on CD-ROM. Agency for Toxic Sub-stances and Disease Registry. U.S. Public Health Service: Washington, DC, 1999.

36. Zhou, H.Y.; Cheung, R.Y.H.; Chan, K.M.; Wong, M.H. Metal concentrations in sed-iments and tilapia collected from inland waters of Hong Kong. Water Res. 1998, 32,3331–3340.

37. FAO/WHO. Evaluation of Certain Food Additives and Contaminants. In WHO Tech-nical Report Series, no. 837. Geneva: WHO, 1993.

38. National Research Council. Recommended Dietary Allowances. 10th ed. NationalAcademy Press: Washington, DC, 1989; 241–243, 284.

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