Levels of organochlorine pesticide residues in marine-, surface-, ground- and drinking waters from the Eastern Cape Province of South Africa

Persistent organochlorine pesticides (OCPs) such as DDT and its metabolites (DDDs and DDEs). chlordane, hexachlorobenzene (HCB), heptachlor and endosulfan were determined in drinking-, ground-, surface- and marine waters from the Eastern Cape Province of South Africa. Percentage recoveries of the OCPs from spiked river water ranged from 71.03 +/- 8.15% (dieldrin) to 101.25 +/- 2.17% (alpha-BHC). The levels of OCPs ranged from 5.5 ng/L (2,4-DDD) to 160 ng/L (HCB) in the water samples. Some endocrine disrupting OCPs such as DDT, DDE, heptachlor, endosulfan and chlordane were detected.     

Assessing spatial distribution,sources, and human health risk of organochlorine pesticide residues in the soils of arid and semiarid areas of northwest China

Thirty-two topsoil samples were collected to analyze the residue levels of organochlorine pesticides (OCPs) in topsoil of arid and semiarid areas of northwest China in 2011. Results showed that DDTs were the dominant contaminants with a mean concentration of 12.52 ng/g. The spatial distribution characteristics indicated that α-hexachlorocyclohexanes (HCHs) were mainly used in rural sites, whereas hexachlorobenzene (HCB) and endosulfan were detected mostly in urban areas. DDTs, heptachlor, and chlordane were found almost equally in both urban and rural areas. Source identification revealed that the current levels of HCHs in soils were attributable to the residues from their historical use and fresh usage of lindane (γ-HCH). DDTs were mainly from historical use and fresh usage of dicofol, and HCB was emitted from the chemical industry. It was also found that the current soil levels of heptachlor were mainly from its historical usage, endosulfan from fresh input, and chlordane from long-range atmospheric transport, respectively. The noncarcinogenic health risk assessment with a model was also conducted using USEPA standards for adults and children. Results indicated that health risk under nondietary exposure to OCPs decreased in the sequence of ΣDDT?>?ΣHCH?>?HCB?>?Σheptachlor?>?Σendosulfan?>?Σchlordane. According to the reference dose from the USEPA, the health risk under nondietary exposure to OCPs in the soil samples was at a relatively safe level.     

Organochlorine pesticides and hexachlorobenzene in tissues of fish and invertebrates caught near a sewage outfall

Concentrations of organochlorine pesticides and hexachlorobenzene (HCB) were determined in 16 fish, 1 mollusc and 1 crustacean species living near a cliff-face sewage outfall. For the 15 organochlorine compounds scanned, HCB, chlordane, dieldrin and SigmaDDT were recorded in highest concentrations. There was considerable variation in concentrations between muscle and liver and between species. Livers had higher concentrations of organochlorines and a higher percentage lipid than muscle. The highest concentrations were recorded in livers of the elasmobranch and tetraodontiform fishes. Organochlorines were only recorded at low concentrations in muscle, often at or near detection limits. No organochlorines were detected in the two invertebrate species.     

Organochlorine contaminants in northeast Atlantic minke whales (Balaenoptera acutorostrata)

Blubber samples of 72 minke whales (Balaenoptera acutorostrata) were obtained from the northeast Atlantic in July and August 1992, and evaluated for organochlorine contamination. The following organochlorines were determined: the industrial chemicals PCBs (polychlorinated biphenyls), and the organochlorine pesticides DDTs (dichlorodiphenyltrichloroethanes), HCHs (hexachlorocyclohexaneb), HCB (hexachlorobenzene) and CHLs (chlordanes). The concentrations of SigmaPCB (sum of concentrations of 18 PCB congeners) and SigmaDDT (sum of concentrations of p,p'-DDT, p,p'-DDE, p,p'-DDD, o,p'-DDT and o,p'-DDD) ranged from 0.6-20.8 and 0.5-14.8 microg g(-1) lipid weight, with mean concentrations at 3.8 and 2.5 microg g(-1) lipid weight, respectively. The mean concentrations of HCB, the chlordane metabolites oxychlordane, cis-chlordane and trans-nonachlor, and the HCH isomers (alpha-, beta- and gamma-HCH) were all < 1 microg g(-1) lipid weight. Significantly higher concentrations of the three major pollutants (SigmaPCB, SigmaDDT and SigmaCHL) were found in mature males as compared to mature females and juveniles of both sexes. No such relationship was found for SigmaHCH and HCB. Stomach contents of northeast Atlantic minke whales indicate considerable heterogeneity in the diet when comparing different years, seasons and geographical areas. However, without knowing more about the minke whale migration pattern, or possible geographical segregation with age and sex, the interchemical variation of organochlorines between sampling areas may not reflect true geographical differences.     

Accumulation features of persistent organochlorines in resident and migratory birds from Asia

Concentrations of organochlorine contaminants including polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), chlordane compounds (CHLs), hexachlorobenzene (HCB) were determined in the resident and migratory birds, which were collected from India, Japan, Philippines, Russia (Lake Baikal) and Vietnam. Accumulation patterns of organochlorine concentrations in resident birds suggested that the predominant contaminants of each country were as follows: Japan--PCBs Philippines--PCBs and CHLs, India--HCHs and DDTs, Vietnam--DDTs, and Lake Baikal--PCBs and DDTs. The migratory birds from Philippines and Vietnam retained mostly the highest concentrations of DDTs among the organochlorines analyzed, indicating the presence of stopover and breeding grounds of those birds in China and Russia. On the other hand, migratory birds from India and Lake Baikal showed different patterns of organochlorine residues, reflecting that each species has inherent migratory routes and thus has exposure to different contaminants. Species which have breeding grounds around the Red Sea and Persian Gulf showed high levels of PCBs, indicating the presence of areas heavily polluted by PCBs in the Middle East.     

Concentration of organochlorine pesticides in wine corks

Wine corks were extracted and analyzed for 23 organochlorine pesticides, including alpha-, beta-, and gamma-hexachlorocyclohexanes (HCH), hexachlorobenzene, DDT, DDE and DDD, chlordane, endosulfan, dieldrin, aldrin, and endrin. This was done to investigate the occurrence, concentrations, composition profiles, and possible sources of organochlorine contamination. All groups of compounds were detected in every sample investigated, with the exception of aldrin and endrin. The total concentrations of organochlorine compounds in all samples ranged from 75-120 ng/g lipid, and for most compounds, the concentrations of organochlorines in cork were consistent with published data for other plant tissues. Differences in the relative abundances of the various classes of organochlorine pesticides were substantial and were probably due to differences in the pesticide usage practices of the various regions in which the cork producing trees were grown.     

Levels of Organochlorine Pesticide Residues in Marine-, Surface-, Ground- and Drinking Waters from the Eastern Cape Province of South Africa

Abstract

Persistent organochlorine pesticides (OCPs) such as DDT and its metabolites (DDDs and DDEs), chlordane, hexachlorobenzene (HCB), heptachlor and endosulfan were determined in drinking-, ground-, surface- and marine waters from the Eastern Cape Province of South Africa. Percentage recoveries of the OCPs from spiked river water ranged from 71.03 ± 8.15% (dieldrin) to 101.25 ± 2.17% (α-BHC). The levels of OCPs ranged from 5.5 ng/L (2,4-DDD) to 160 ng/L (HCB) in the water samples. Some endocrine disrupting OCPs such as DDT, DDE, heptachlor, endosulfan and chlordane were detected.     

Biomagnification of organochlorines along a Barents Sea food chain

To trace the biomagnification of organochlorines in marine food chains near Svalbard, which may lead to the high organochlorine concentrations in top predators from the area, we compared concentrations and patterns of organochlorines in selected taxa. The pelagic crustaceans, Calanus spp. (copepods), Thysanoessa spp. (euphausiids), Parathemisto libellula (amphipod), and the fish species, Boreogadus saida (polar cod) and Gadus morhua (cod) were selected to represent the lower trophic levels in the food web. Four seabird species were chosen at the higher trophic levels, Uria lomvia (Brünnich's guillemot), Cepphus grylle (black guillemot), Rissa tridactyla (black-legged kittiwake) and Larus hyperboreus (glaucous gull). We found low concentrations of the organochlorines sigma hexachlorocyclohexanes (sigma HCHs), hexachlorobenzene (HCB), sigma Chlordanes, sigma DDTs and sigma polychlorinated biphenyls (sigma PCBs) in crustaceans (11-50 ng g-1 lipid wt.) and fish (15-222 ng g-1 lipid wt.). In seabirds, the organochlorine concentrations biomagnified one to three orders of magnitude dependent on species and compound class. Glaucous gulls had the highest concentrations of all organochlorines. The organochlorine levels in all taxa except glaucous gull were comparable to those recorded in similar species in the Canadian Arctic. The organochlorine pattern changed from crustaceans and fish to seabirds. Moving up the food chain, the relative contribution of sigma HCHs, HCB and sigma Chlordanes decreased, and the relative contribution of sigma DDTs, sigma PCBs, persistent compounds and metabolites increased. The results reflected trophic transfer of organochlorines along the food chain as well as different elimination potentials due to direct diffusion in crustaceans and fish, and higher contaminant metabolic activity in seabirds.     

Temporal trends of organochlorine contamination in Black Guillemots in Iceland from 1976 to 1996

The levels of several different persistent organochlorines (OCs) in Black Guillemots Cepphus grylle, collected during the summers of 1976-1996 at Breioafj?rour in W-Iceland, were investigated. The levels of about 40 different organochlorines (PCBs, DDTs, chlordanes, toxaphenes, HCH, HCB) were compared with respect to age, sex, fat content, and year of collection. The levels of PCBs correlated very closely with those of DDE, indicating long-range transport as the major source of these contaminants in Iceland, with the ratio PCBs/DDE mostly in the range of 2-5. Unlike the Gyrfalcon Falco rusticolus, the organochlorine levels did not seem to accumulate substantially with age, neither in males nor females. The variation in the levels of OCs at the age of 2 years was even greater than the variation in OC levels over an age range of 12 years. In immature birds the levels of PCBs, DDE, HCB and beta-HCH declined very slowly (T(1/2) from 12 to 20 years) over the years 1976-1996, whereas the levels of alpha-HCH and p,p'-DDT declined much faster. The levels of trans-nonachlor, alpha-chlordane, gamma-chlordane, oxychlordane, and toxaphene did not correlate with the year of collection. As the Black Guillemot is mostly a resident seabird, feeding mainly on small fish and invertebrates, this investigation should give a good indication of the temporal trends of organochlorine pollution at Breioafj?rour, Iceland, during this 20 year period and is likely to reflect baseline trends in the marine environment of the North-Atlantic Ocean.     

Organochlorine residues in finfish from Maryland waters 1976-1980

Organochlorine pesticide and herbicide levels were monitored in samples of a variety of edible finfish harvested from the Maryland section of the Chesapeake Bay and its tributaries over a five-year period (1976-80). Qualitative and quantitative information was obtained for the various polychlorinated biphenyls (PCB's), heptachlor, alpha-BHC, chlordane, DDD, DDE, DDT, dieldrin, endrin, heptachlorepoxide, lindane, mirex, methoxychlor, aldrin, toxaphene, hexachlorobenzene, kepone and dacthal. In addition to analyses of the flesh of the animals, organochlorine residue levels were determined in roe or gonad tissue of several samples. Striped bass, white perch and yellow perch samples showed significantly higher concentrations of certain of these substances in roe or gonad tissue, especially PCB's, chlordane, DDD and dieldrin. Significantly higher levels of six organochlorine residues were found in the gonad tissue of striped bass; however, similar studies on gonad tissue of American Shad, harvested from the same region, show no such enhancement. Rather, the reverse is true; levels of certain organochlorine residues are higher in flesh tissue. All mean values, and virtually all individual values of organochlorine concentrations in the edible portion of the fish were within the U.S. Food and Drug Administration guideline, where such guidelines have been established.     

Organochlorine compounds in bovine milk from the state of Mato Grosso do Sul – Brazil

Organochlorines are highly hydrophobic, synthetic organic pollutants that accumulate in the environment and in food webs. The primary route of human exposure to organochlorines is through food-mainly fat-rich food of animal origin such as meat, fish, and dairy products. Here we determined the presence and concentration of organochlorine residues in pasteurized milk from Mato Grosso do Sul, Brazil, to monitor consumer exposure to these contaminants. Organochlorine pesticides in milk samples were analyzed using solid phase extraction in octadecyl silica-prepacked columns and identified by gas chromatography using an electron capture detector. Of the 100 composite samples analyzed, more than 90% contained residues of organochlorine pesticides: aldrin was present in 44% of the samples, followed by ∑DDT (36%), mirex (34%), endosulfan (32%), chlordane (17%), dicofol (14%), heptachlor (11%) and dieldrin (11%). Compared to the values established by law, the concentration of the compounds in some samples was above the reference values. Given the importance that milk and its products have in the human diet, it is essential to know whether the levels of pesticide residues are kept well below the recommended levels to minimize the risk to human health.     

Chemical trends in Finnish wildlife: A study on time trends in starlings during 1967–1983

The OECD monitoring programmes 1966–1971 and 1972–1975 have been extended at national level in Finland to 1983 by analysing chlorinated hydrocarbons, mercury and chlorophenols in starlings (terrestrial environment). At the end of the study period levels in fresh muscles were for DDE 10, PCB 30, HCB 1, Lindan 8 and mercury 50 ppb. Of chlordane residues only traces of oxychlordane were found. Ten different chlorophenol compounds were detected at ppb levels, but most of them in only few samples. Pentachlorophenol was most frequently found. Statistical treatment of the analysis results gave some decreasing trends which were very significant for DDE, DDT and PCB 1967–1983, significant for mercury 1967–1983 and somewhat significant for lindane 1978–1983.     

Mercury and organochlorine content of Dipper Cinclus cinclus eggs in south-west Ireland: trends during 1990-1999

A sample of 124 deserted/infertile dipper (Cinclus cinclus) eggs was collected in south-west Ireland during six seasons (1990-1994 and 1999) and analysed for mercury and organochlorines. Mercury was detected in three of the 6 years but no trend was observed. DDT occurred above the limit of detection in only two eggs, one each in 1993 and 1994. In contrast, two derivatives of DDT (DDE and TDE) were found much more commonly. DDE occurred in over 87% of eggs, while TDE contamination was less widespread and reached a maximum of 60% in 1993, with none detected in 1991 or 1999. There was no trend in occurrence of DDE or TDE across years. PCB contamination was present consistently over the 10-year period, with little change in the proportion of contaminated eggs collected over time. In all years, the lowest recorded occurrence of total PCBs was 69% expressed on a formulation basis as Arochlor 1254. PCB congeners 138, 153 and 180 dominated. The congener pattern was similar across years with the exception of 1990 when congener 118 dominated. A distinct trend of high values of contaminants was observed in 1990 and 1993. In 1990, PCB 118 was the dominant contaminant, while in 1993, HEOD, DDE, PCB 138 and PCB 153 were primary contributors to the observed result. Other contaminants (HCB, PCB 101, gamma-HCH, PCB 170 and PCB 180) showed little obvious patterns between years and occurred at relatively low levels. No pattern was observed in contaminants when eggs were grouped according to river or altitude. These data provide a baseline for organochlorine contamination levels in Irish freshwater ecosystems against which future trends can be assessed.     

Organochlorine contaminants in eggs of seabirds in the Northwest Atlantic, 1968-1984

Eggs of three seabird species, double-crested cormorant (Phalacrocorax auritus). Leach's storm-petrel (Oceanodroma leucorhoa), and Atlantic puffin (Fratercula arctica) were collected at four-year intervals from 1968 to 1984, from colonies in eastern Canada and analyzed for organochlorines. This monitoring study was established to provide data on contamination of the marine environment and possible implications for seabird health. Long-term trend data are presented for PCBs, DDE, dieldrin, HCB, oxychlordane, heptachlor epoxide, HCH and mirex. DDE and PCBs declined significantly in all species from the Bay of Fundy. DDE declined significantly in puffins and petrels while PCBs declined only in petrels from the Atlantic coast of Newfoundland. Generally DDE declined more than PCBs. Dieldrin, oxychlordane, HCH and mirex levels decreased at some locations but were stable at others. Hexachlorobenzene and heptachlor epoxide levels remained steady or increased significantly, depending on the species and location. Organochlorine levels in cormorants from the St. Lawrence River estuary showed no significant trends.     

Organochlorine residues in finfish from Maryland waters 1976–1980

Abstract

Organochlorine pesticide and herbicide levels were monitored in samples of a variety of edible finfish harvested from the Maryland section of the Chesapeake Bay and its tributaries over a five‐year period (1976–80). Qualitative and quantitative information was obtained for the various polychlorinated biphenyls (PCB's), heptachlor, α‐BHC, chlordane, DDD, DDE, DDT, dieldrin, endrin, heptachlor‐epoxide, lindane, mirex, methoxychlor, aldrin, toxaphene, hexachlorobenzene, kepone and dacthal.

In addition to analyses of the flesh of the animals, organochlorine residue levels were determined in roe or gonad tissue of several samples. Striped bass, white perch and yellow perch samples showed significantly higher concentrations of certain of these substances in roe or gonad tissue, especially PCB's, chlordane, DDD and dieldrin. Significantly higher levels of six organochlorine residues were found in the gonad tissue of striped bass; however, similar studies on gonad tissue of American Shad, harvested from the same region, show no such enhancement. Rather, the reverse is true; levels of certain organochlorine residues are higher in flesh tissue.

All mean values, and virtually all individual values of organochlorine concentrations in the edible portion of the fish were within the U.S. Food and Drug Administration guideline, where such guidelines have been established.     

Accumulation of organochlorine contaminants in double-crested cormorants

Cormorant eggs and lipid samples from juvenile Cormorants were analyzed for 14 organochlorine contaminants. Low concentrations (geometric mean < 0.05 microg/g) of hexachlorobenzene (HCB), lindane, oxy-chlordane, heptachlor epoxide, dieldrin, endrin, mirex, DDD and DDT in eggs primarily reflected the wintering-ground origin of organochlorine contaminants. Overall geometric mean concentrations of DDE and PCBs in Cormorant eggs were 3.90 and 2.22 microg/g egg respectively, and would not affect reproduction or eggshell thickness. Eggshells averaged 0.44 mm in thickness and no correlation (r2 = 0.17) with log-transformed DDE residues in Cormorant eggs was evident. Only DDE and PCBs were detected in lipid samples from 5- to 8-week-old Cormorants (geometric mean approximately 1.0 microg/g lipid for each compound). The PCB: DDE ratios in Cormorant lipid from some individual colonies were 2-3.5 times greater than the ratio in eggs from the same colony, suggesting an accumulation of PCBs related to local diet. Juvenile Cormorants might serve as regional indicators of chemical residue contamination in Alberta, and provide a temporal perspective on changes in contaminant burdens in aquatic ecosystems.     

Contamination by butyltin compounds and organochlorine residues in green mussel (Perna viridis, L.) from Thailand coastal waters

In order to elucidate marine pollution by butyltins and organochlorine residues in coastal waters of Thailand, green mussels (Perna viridis) were collected in 1994 and 1995 and analyzed. Butyltin compounds, such as tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT), were detected in most mussel samples, ranging from 4 to 800 ng g(-1) wet wt (as total). The composition of butyltin derivatives in green mussel was in the order of TBT > DBT > MBT. The results indicated that butyltin contamination was widespread, particularly in high boating areas and in coastal aquaculture facilities. Concentrations of organochlorine residues were much lower than of butyltin compounds. Among organochlorine residues examined, dichlorodiphenyltrichloroethane compounds (DDTs) were found to be the highest, followed by polychlorinated biphenyls (PCBs) > chlordane compounds (CHLs) > hexachlorocyclohexanes (HCHs) > hexachlorobenzene (HCB). To our knowledge, this is a first report on the detection of butyltin residues in Thailand coastal waters.     

Geographical distribution of persistent organochlorines in air, water and sediments from Asia and Oceania, and their implications for global redistribution from lower latitudes

Persistent organochlorines in air, river water and sediment samples were analysed from eastern and southern Asia (India, Thailand, Vietnam, Malaysia, Indonesia) and Oceania (Papua New Guinea and Solomon Islands) to elucidate their geographical distribution in tropical environment. The concentrations of organochlorines in these abiotic samples collected from Taiwan, Japan and Australia were also monitored for comparison. Atmospheric and hydrospheric concentrations of HCHs (hexachlorocyclohexanes) and DDTs (DDT and its metabolites) in the tropical developing countries were apparently higher than those observed in the developed nations, suggesting extensive usage of these chemicals in the lower latitudes. CHLs (chlordane compounds) and PCBs (polychlorinated biphenyls) were also occasionally observed at higher levels in the tropics, implying that their usage area is also expanding southward. Distribution patterns of organochlorines in sediments showed smaller spatial variations on global terms, indicating that the chemicals released in the tropical environment are dispersed rapidly through air and water and retained less in sediments. The ratios of organochlorine concentrations in sediment and water phases were positively correlated with the latitude of sampling, suggesting that persistent and semivolatile compounds discharged in the tropics tend to be redistributed on a global scale.     

National survey of the levels of persistent organochlorine pesticides in the breast milk of mothers in China

The occurrence of persistent organochlorine pesticides (OCPs) in breast milk samples collected from mothers from twelve provinces in mainland China was investigated. Dichlorodiphenyltrichloroethanes (DDTs) were the most prevalent agent, followed by HCHs and HCB, whereas levels of chlordane compounds, drins and mirex were lower. The relatively lower DDE/DDT ratio in the Fujian rural area suggested more recent exposure to DDT than in other areas. The mean level of DDTs in breast milk from the southern China was higher than those from northern China (p < 0.05). A positive correlation was observed between concentration of DDTs in human milk and consumption of animal-origin food, suggesting that this parameter could play an important part in influencing OCPs burdens in lactating women. The mean estimated daily intakes of different OCPs for breastfed infants were lower than the tolerable daily intake.     

Organochlorine pesticide residue and PCBs in harbour porpoise (Phocoena phocoena) incidentally caught in Scandinavian waters

During Norwegian and Danish harbour porpoise projects 1987-1991, subcutaneous blubber samples of 34 male harbour porpoises (Phocoena phocoena) were collected. Animals from three geographical locations, ranging from 56 degrees N, 12 degrees E to 71 degrees N, 26 degrees E, were chosen in order to study the organochlorine (OC) contamination in this species inhabiting the northeastern part of the North Atlantic Ocean, the northern North Sea and Kattegat, at the locations of Tufjord, Vestlandet and Gilleleje, respectively. Analytical standards used consisted of the industrial chemicals PCBs (22 individual PCB congeners and 6 industrial mixtures which contained 104 PCB congeners or group of congeners) and HCB, and the organochlorine pesticides DDT, HCH, the cyclodienes endrin, dieldrin and the chlordane metabolites oxychlordane and trans-nonachlor, and heptachlor epoxide. A total of 16 PCB congeners or groups of congeners, all the DDT metabolites except o,p'-DDD, and all the pesticides were detected in all animals. The concentrations of sigmaPCB (sum of concentrations of 47 detected PCB congeners) and sigmaDDT (sum of concentrations of all DDT detected compounds) ranged from 3.7-65.3 and 3.2-45.0 microg g(-1) lipid weight, respectively. The range of mean concentrations of dieldrin, endrin and trans-nonachlor was 1-3 microg g(-1), while mean concentrations of HCHs, heptachlor epoxide, and HCB were <1 microg g(-1). No significant variation in PCB congener pattern was apparent between geographical areas. The major PCB congeners nos 147/123, 153, 138/163/164, 182/187 and 180 at Gilleleje, Vestlandet and Tufjord represented 53%, 45% and 44% of sigmaPCB, respectively. A significant difference was found between the number of PCB congeners in blubber of newborn and older porpoises. This might indicate the presence of a blood/placenta barrier and/or selective mammary transport of PCBs with specific structures. A significant OC accumulation with age was apparent, with the exception of HCB and HCHs. Geographical differences in the levels of OCs were apparent for all compounds except for dieldrin and heptachlor epoxide. Significantly higher levels of chlordane metabolites (trans-nonachlor and oxychlordane) and endrin were found in the group of animals from the northern location Tufjord, while sigmaDDT, p,p'-DDTs, HCHs and PCBs were highest in the group of animals from the southern location Gilleleje. Highest levels of the o,p'-substituted DDTs were found in specimens from the middle location Vestlandet. These findings indicate little or no regular migration of harbour porpoise between these three locations. No correlations were found between OC concentrations and blubber thickness. Although mean values of sigmaDDT and sigmaPCB were in the lower end of previously reported levels in harbour porpoise from adjacent waters in the eastern part of the North Atlantic Ocean and along the coasts of North America, these levels are relatively high. The organochlorine concentrations in harbour porpoises in the present study were 2-3 times higher than corresponding OC levels detected in harbour seals (Phoca vitulina) from the same areas.