Patterns of contamination by organochlorines and mercury in the eggs of two river passerines in Britain and Ireland with reference to individual PCB congeners

Unhatched eggs were collected in 1988 and 1990 from nests of the Eurasian Dipper Cinclus cinclus and the Grey Wagtail Motacilla cinerea in Wales, eastern Scotland and south-western Ireland. Mercury concentrations in Dipper eggs (geometric means 0.45-0.91 ppm (microg g(-1)) dry mass) were significantly lower in eastern Scotland than in either south-western Ireland or Wales, where the incidence of detectable residues increased markedly between 1988 (2% of eggs) and 1990 (69%). By contrast, DDE (geometric means 0.63-3.54 ppm in lipid), TDE (<0.01-1.80 ppm), DDT (<0.01-0.65 ppm), total PCBs (3.99-10.47 ppm), HEOD (0.39-0.61 ppm) and HCB (0.02-0.13 ppm) were all significantly higher in Scottish eggs than others. Around 33-46% of the total PCB burden in Dipper and Grey Wagtail eggs could be accounted for by six congeners (IUPAC numbers 118, 180, 101, 153, 138 and 170). Amongst these attributable PCBs, Dipper eggs from eastern Scotland were dominated by congener 153 (2,2',4,4',5,5'-hexachlorobiphenyl), whilst Welsh and Irish eggs were dominated by congener 118 (2,3',4,4',5-pentachlorobiphenyl). With the latter exception, all the individual congeners were found at significantly higher concentrations in Scottish eggs than others. Grey Wagtail eggs were dominated by congeners 118 and 101 (2,2,4,5,5'-pentachlorobiphenyl). In general, these congeners are common, widespread, and dominant components in the eggs of other wild birds for which data are available. Consistent with the low to medium levels of contaminants found in Dipper eggs, there was only slight evidence of any toxic effects. These included moderate shell thinning in relation to increasing DDE, and some evidence that contaminants had contributed to egg failure.     

Long-term trends in organochlorine and mercury residues in some predatory birds in Britain

Residue levels of organochlorine pesticides (HEOD, DDE), polychlorinated biphenyls (PCBs) and mercury (Hg) in the livers of five predatory bird species were monitored in Britain over a 28-year (1963-1990) period. Of two raptor species, sparrowhawks contained higher levels of most chemicals than did kestrels. Among three fish-eaters, herons and kingfishers contained the highest levels of DDE and HEOD, while herons and great-crested grebes contained the highest levels of PCBs and mercury. Species differences were related partly to diet and habitat. In sparrowhawks and kestrels, residues of HEOD and DDE were higher in eastern, arable districts than elsewhere, especially in the 1960s and 1970s. In the fish-eaters, similar regional differences in residue levels were apparent in herons, especially in the 1970s, but not in the other species, for which samples were smaller. Over the 28 years, most species showed significant downward trends in HEOD, DDE and Hg levels, but only two fish-eaters showed significant declines in PCB levels. The downward trends in DDE and HEOD followed successive restrictions in the use of organochlorine pesticides, and were accompanied by recoveries in the populations and breeding success of affected species. Downward trends in mercury were associated with reductions in both agricultural use and industrial emissions.     

Influence of age,season, body condition and geographical area on concentrations of chlorinated and brominated contaminants in wild mink (Neovison vison) in Sweden

The wild mink has gained acceptance as a sentinel species in environmental monitoring. However, only limited data are available in the literature on factors driving variability in concentrations of organic pollutants in this species. This study characterizes the differences in contaminant concentrations in subcutaneous fat of male mink from four different areas in Sweden and demonstrates how age, season and body condition influence concentrations of polychlorinated biphenyl (PCB) congeners, polybrominated diphenyl ether (PBDE) congeners (including methoxylated forms, MeO-PBDEs), as well as the pesticides dichlorodiphenyldichloroethylene (DDE), chlordane and hexachlorobenzene (HCB). The data were statistically treated using multiple regression and principal component analysis. The ∑PCB concentration and concentrations of PCB congeners 138, 156, 157, 180, 170/190, 189, 194, 206, 209 as well as PBDE 153/154 varied with age. Season had an influence on ∑PCB, PBDE 47 and PBDE 153/154 concentrations, as well as concentrations of most PCB congeners, with the exception of PCB 101, 110, 141 and 182/187. Lean mink had higher concentrations of most PCBs and PBDEs than mink with larger fat depots. The analyzed pesticides (DDE, oxychlordane, HCB) showed no systematic variation with season, age or body condition. The concentrations of MeO-PBDEs were generally low and 6MeO-PBDE 47 was the most commonly detected MeO-PBDE in mink from marine, brackish and freshwater areas. The results indicate that age, season and body condition are factors that may influence the concentrations of PCBs and PBDEs, and it is thus recommended to take these factors into account when analyzing mink exposure data.     

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.     

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 pesticides, PCBs and mercury in antarctic and subantarctic seabirds

Between 1978 and 1983, eggs from 15 species of Antarctic and Subantarctic seabirds were collected and analysed for organochlorine pesticides, PCBs, and mercury residues. The lowest levels of these chemicals were detected in the eggs of Adélie Penguins from Prydz Bay. Antarctica. On a wet weight basis, the mean concentrations in eggs of these penguins were 0.01 μg/g HCB, 0.005 μg/g DDE, less than 0.1 μg/g PCBs (1260) and 0.02 μg/g mercury. Such values indicate that the environmental levels of these contaminants in the biotypes of these species are extremely low, and present no significant threat.

The highest levels of contaminants were found in the eggs of species which breed in Antarctica and migrate to regions well north of the Antarctic Convergence in the non-breeding season. On a wet weight basis, Northern Giant-Petrel eggs contained 0.11 μg/g HCB, 0.95 μg/g DDE and 1.8 μg/g PCB (1260), and 1.8 μg/g mercury. There are indications that DDE levels are increasing for both Southern and Northern Giant-Petrels, and it is possible that reports of a decreasing number of breeding pairs of these species at several colonies are due to one or more of these contaminants reaching toxic levels.

Analysis of penguin tissues show that preen gland lipid is suitable for monitoring the body burden of organochlorine insecticides and PCBs in seabirds.

Variation in DDE and mercury residue levels for some of these species suggest that the biotypes in which they live are quite different, and that the Antarctic Convergence may have a major influence in protecting the Antarctic ecosystem from these pollutants.     

Polychlorinated biphenyls, organochlorinated pesticides, and polybrominated diphenyl ethers in the cerebral cortex of wild river otters (Lontra canadensis)

We measured the levels of ortho-substituted polychlorinated biphenyls (PCB), organochlorinated pesticides (OCP), and polybrominated diphenyl ethers (PBDE) in the cerebral cortex of river otters (Lontra canadensis) trapped from Ontario and Nova Scotia between 2002 and 2004. The mean concentration of total PCBs was 70.9+/-12.1 ng/g l.w., and congeners 153, 180 and 138 accounted for nearly 60% of the sum. The mean concentration of total OCPs was 21.2+/-3.7 ng/g l.w., and hexachlorobenzene (32.6% of total) and DDE (28.1%) accounted for the majority. The mean concentration of total PBDEs was 3.2+/-0.6 ng/g l.w., and congeners 99 (44.9%), 153 (30.5%), and 100 (24.7%) were measured at the indicated percentages. There was no relationship between these residue data and concentrations of brain mercury or neurochemical receptors and enzymes as determined in earlier studies on these same animals.     

Organochlorine pesticides and polychlorinated biphenyl congeners in lanner Falco biarmicus feldeggli Schlegel chicks and lanner prey in Sicily, Italy

This paper reports on research conducted to elucidate the risk posed to the Sicilian population of the endangered lanner falcon Falco biarmicus feldeggii Schlegel by organochlorine (OC) pesticides and polychlorinated biphenyls (PCBs), as part of a wider study on contaminant risk to the lanner. Seventeen lanner nest sites were studied in northern and central Sicily. Sampling (in 2005) and analysis were carried out for selected OC pesticides and PCB congeners in lanner chick blood (15 chicks from 6 nest sites) and in two of the main lanner prey species, magpie Pica pica (36 individuals from 6 lanner nest sites) and rock dove Columba livia (10 individuals from 2 lanner nest sites). No OC and PCB residues were found in lanner chick blood above the detection limits, except for one solitary congener PCB153 (21.8 ng g(-1) wet weight), suggesting that these contaminants do not pose a significant risk to lanner chicks in the study area. Magpie and dove appeared mostly free of contamination with OC pesticides, though contamination levels were significantly higher in magpie than in dove. The presence of exceptional DDE and HEOD values in approximately 8% of the P. pica sample, and one P. pica sample showing recent DDT contamination, may indicate a local OC pesticide hazard to some lanner. Future research to further elucidate the contaminant risk to lanner in Sicily is suggested.     

Biomonitoring of persistent organochlorine pesticides, PCDD/PCDFs and dioxin-like PCBs in blood of children from South West Germany (Baden-Wuerttemberg) from 1993 to 2003

In the context of a monitoring program, persistent organic pollutants (POPs) were quantified in the blood of 10 year old children at four different demographic regions in Baden-Wuerttemberg, a highly industrialised federal state in South West Germany. DDE, HCB, PCB 138, PCB 153 and PCB 180 were measured in 1996/1997, 1998/1999, 2000/2001 and 2002/2003 in individual samples of about 400 children per year. PCDD/PCDFs and some relevant coplanar PCBs were determined in pooled samples from children in seven cycles from 1993 to 2003. Blood concentrations of the investigated compounds decreased in that time period by a factor of 2-4 with the exception of most PCDFs. The concentrations of POPs in the blood of the children were distinctly lower than the concentrations reported for adults. Breast feeding was associated with about 30% higher median concentrations of DDE, HCB, PCBs and a 30% increase for mean PCDD/PCDF concentrations. Concerning demographic differences, significant lower concentrations of HCB, PCBs and PCDD/PCDFs could be seen in children from Mannheim compared to the region of Aulendorf. About 10-20% higher concentrations were found in boys compared to girls for HCB, indicator PCBs and PCDD/PCDFs. The pattern of non-ortho and mono-ortho PCBs in the blood of children was similar to the pattern reported for mother's milk, and PCB 126 and PCB 156 contributed about 70% to the toxicity of dioxin-like PCBs and about one-third to total TEQ including PCDD/PCDFs.     

The role of DDE,PCB, coplanar PCB and eggshell parameters for reproduction in the white-tailed sea eagle (Haliaeetus albicilla) in Sweden

The reproduction of white-tailed sea eagles was monitored in 1964-1999 in 3 differently contaminated sub-populations: Baltic Sea coast (Bp), inland central Sweden (Ip) and Lapland (Lp). 249 dead eggs from 205 clutches were obtained for analyses of DDE and PCBs and for eggshell measurements. A desiccation index (Di) value was calculated for each egg as a measure of water loss through the shell. In the highly contaminated Bp, p,p'-DDE concentrations in the eggs decreased continuously and 5-fold during the study period and PCB concentrations decreased 3-fold from the mid 1980s. The PCB pattern changed slightly over time towards more high-chlorinated congeners but the relative toxicity of the PCB mixture, expressed as 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQ), remained constant and TEQ can be assumed to have decreased in a similar way as PCB over time. Productivity (P), shell thickness (St), shell index (Si) and Di increased over time in the Bp but no change in Di or productivity occurred in the Lp, where residue concentrations were 5-8 times lower. P of the Bp was not correlated to St or Si but was negatively correlated to Di, DDE and PCB. An S-shaped dose-response relationship was indicated between P and DDE. After 1988, when the PCB/DDE ratio was considerably higher than previously, PCB but not DDE concentrations were significantly higher in eggs with dead embryos as compared to undeveloped eggs, implying lethal concentrations of PCB, and a LOEL of 320 pg g-1 TEQ is suggested for embryo mortality. In a subset of 21 eggs, representing productive and unproductive females, analyzed for a selection of coplanar PCB congeners, tris(4-chlorophenyl) methanol and bis(4-chlorophenyl) sulphone, there was no evidence for a correlation between P and any of these compounds. A reduction in residue concentrations in old females did not lead to increased P or improved Di-values, indicating a remaining effect from a previous, higher exposure to contaminants. The inability to reproduce included a high rate of undeveloped eggs, indicating effects at a prezygotic stage. P showed the strongest correlation with Di, and Di was most strongly correlated to DDE. Thus, the remaining effect of previous exposure resulted in a stronger correlation to the symptom (Di) rather than to the suggested causative agent (DDE). LOEL values for depressed P were estimated at 120 micrograms g-1 DDE and 500 micrograms g-1 PCB (lipid basis). It is concluded that the major reason for depressed P during the study period was DDE, but that effects also from PCB were largely concealed by the effects from DDE.     

Congener-specific analysis of non-dioxin-like polychlorinated biphenyls in blood collected from 195 pregnant women in Sapporo City, Japan

We conducted a congener-specific analysis of non-dioxin-like polychlorinated biphenyls (non-dioxin-like PCBs) in blood collected between July 2002 and July 2004 from 195 pregnant women living in Sapporo City of Hokkaido Prefecture, Japan. The present study is one of the few studies in which full congener concentrations of non-dioxin-like PCBs have been measured in the blood of pregnant women. Of the 195 pregnant women, 101 were primipara (mean: 28.8 years, median: 28.0 years) and 94 were multipara (mean: 32.3 years, median: 33.0 years). Among the 197 non-dioxin-like PCB congeners, 58 congeners were identified in the blood of pregnant women. The arithmetic mean total concentrations of 58 non-dioxin-like PCB congeners in the blood of primiparous and multiparous mothers in Sapporo City were 42.2-329.3 (mean: 114.5, median: 98.6) and 31.5-258.0 (mean: 100.3, median: 91.4)ngg(-1)lipid, respectively. The results show that the contamination of non-dioxin-like PCBs in the blood of women has decreased compared to past levels in other domestic areas, in which the subject age was similar to that in this study. The results of the present study indicate that current levels of non-dioxin-like PCBs in the blood of Japanese women and can be used as baseline data for future temporal trends. The sums of the ratios of the concentrations of hexaCBs and heptaCBs to the total concentrations of 58 non-dioxin-like PCB congeners in the blood of primiparous and multiparous mothers were 78.5% and 77.7%, respectively. The hexaCBs ratios in the blood of primiparous and multiparous mothers were 45.4% and 44.7%, respectively. HexaCB-153 among hexaCBs congeners, the most abundant congener in the blood of primiparous and multiparous mothers, contributed approximately 22.0% and 21.8% to the total concentrations of 58 non-dioxin-like PCBs congeners that were measured in the blood, respectively. Among the non-dioxin-like PCB congeners measured in the present study, hexaCB-138, heptaCB-170, heptaCB-180, and heptaCB-182/heptaCB-187 also showed high ratios to total concentrations of 58 non-dioxin-like PCB congeners detected in the blood of primiparous and multiparous mothers. With regard to the relationship between the total concentrations of 58 non-dioxin-like PCB congeners in maternal blood and the number of deliveries or the age of primiparous and multifarious mothers, the total levels of these PCB congeners tended to decreases with increases in the number of deliveries and significantly increased with increasing maternal age in both groups. Furthermore, significant correlations were observed between the total concentrations of these PCB congeners in blood and the age of primiparae and multiparae. The concentrations of hexaCB-153 in the blood of primiparous and multiparous mothers showed a close correlation to the total concentrations of these PCBs, suggesting that hexaCB-153 could be an indicator of total concentrations of non-dioxin-like PCB congeners in the blood of pregnant women.     

Fish from industrially polluted freshwater as the main source of organochlorinated pollutants and increased frequency of thyroid disorders and dysglycemia

In a certain area of Michalovce district in East Slovakia, heavy industrial pollution by polychlorinated biphenyls (PCBs) developed in 1955-1984 and very high PCB levels in environmental and human samples are still persisting. Recently, a total of 2045 adults from this and the surrounding background pollution area have been examined using questionnaire data, thyroid volume by ultrasound (ThV), urinary iodine and serum levels of 15 PCB congeners, hexachlorobenzene (HCB), 2,2'-2-bis(4-chlorobiphenyl)-1,1-dichloroethylene (DDE), 2,2'-bis(4-chlorophenyl)-1,1,1-trichloroethane (DDT), alpha-, beta- and gamma-hexachlorocyclohexane (HCH), thyrotropin (TSH), free thyroxine (FT4), anti-thyroperoxidase antibodies (TPOab) and fasting glucose. As based on our previous findings of strikingly high level of PCBs in fish from high pollution area (e.g. mean level of 375430 ng/g lipid) and considerably lower, but still relatively high level in background pollution area (e.g. mean PCB level of 5150 ng/g), the information on the frequency of fish meals and approximate annual consumption of fish from local waters was obtained by questionnaires. The association of contaminated fish consumption with very high blood levels of PCBs, DDE and HCB and increased ThV as well as with increased frequency of positive TPOab, high values of FT4 and impaired fasting glucose (IFG) was found. These associations were also confirmed in 16 marital pairs from high pollution area with very high PCB level in both members associated with high fish consumption. It was concluded that, due to persistent heavy pollution of waters, soil and food chain namely by PCBs, but also by pesticides (e.g. DDE and HCB) resulting from their previous extensive use in agriculture, the fish from local waters still remains the most important source of these toxic pollutants which results in considerable adverse health effects.     

Bioaccumulation of polychlorinated biphenyls in ranid frogs and northern water snakes from a hazardous waste site and a contaminated watershed

Livers of bullfrogs (Rana catesbeiana) from a polychlorinated biphenyl (PCB) contaminated watershed and hazardous waste site located in Pickens County, South Carolina, contained significantly higher concentrations of PCBs (2.33 and 2.26 ppm, respectively) than those from a reference site (0.05 ppm). Green frogs (R. clamitans) from the two contaminated sites also accumulated higher levels of PCBs (2.37 and 3.88 ppm, respectively) than those from the reference site (0.02 ppm). No temporal variation was observed in PCB concentrations of bullfrogs or green frogs from the contaminated sites between 1992 and 1993. Levels of PCBs in the livers of northern water snakes (Nerodia sipedon) were significantly higher in snakes from the contaminated watershed (13.70 ppm) than in those from the waste site (2.29 ppm) and two reference sites (2.50 and 1.23 ppm). When compared to frogs, significantly higher bioaccumulation occurred in water snakes from the contaminated watershed. No significant differences in PCB levels were found with respect to sex or body size (snout-vent length (SVL) or body mass) for frogs or snakes. PCBs were detected also in eggs of both frogs and snakes. Results of this study provide baseline data and document the bioaccumulation of PCB residues in frog and snake tissues; however, the significance of these tissue residues to reproduction, survival, growth/development, and population dynamics in contaminated habitats is unknown.     

Occurrence of PAHs, PCBs and organochlorine pesticides in the Tonghui River of Beijing, China

Tonghui River, a typical river in Beijing, People's Republic of China, was studied for its water and sediment quality, by determining the levels of 16 polycyclic aromatic hydrocarbons (PAHs), 12 polychlorinated biphenyls (PCBs) and 18 organochlorine pesticides in water and sediment samples. Total PAHs, PCBs and organochlorine pesticides concentrations in water varied from 192.5 to 2651 ng/l, 31.58-344.9 ng/l and 134.9-3788 ng/l, respectively. The total PAHs, PCBs and organochlorine pesticides concentrations in surficial sediments were 127-928 ng/g, 0.78-8.47 ng/g and 1.79-13.98 ng/g dry weight, respectively. The results showed that the concentration of these selected organic pollutants in sediment was higher than those in surface water. It may be due to the fact that organic hydrophobic pollutants tend to stay in the sediments. The PAHs were dominated by 2-, 3-ring components in water samples and by 3- and 4-ring compounds in sediment. For organochlorines, alpha-HCH, delta-HCH, Heptachlor, Endosulfan II, DDT are the major organochlorine pesticides in water while Heptachlor, Dieldrin and DDE composed of 95% of total organochlorine pesticides in sediment. For HCHs (HCHs=alpha-HCH+beta-HCH+gamma-HCH+delta-HCH), the predominance of alpha-HCH of total HCHs were clearly observed in water and sediment. PCB18, PCB31 and PCB52 were predominant in water, on average these compounds collectively accounted for 67% of total PCBs. But in sediment, the predominant compounds were PCB28, PCB31 and PCB153, which accounted for 71% of total PCBs in sediment. The levels of micro pollutants in our study areas were compared with other studies.     

Organochlorine contaminants and eggshell thinning in grebes from prairie Canada

Eggs of five species of grebe were collected from Manitoba, Saskatchewan and Alberta during 1982-1987: red-necked (Podiceps grisegena), horned (P. auritus), eared (P. caspicus), western (Aechmophorus occidentalis) and pied-billed (Podilymbus podiceps). DDE and PCBs were present in all samples analyzed, whereas dieldrin, mirex and oxychlordane were occasionally present at low levels. Mercury was present at low levels in all samples for which it was analyzed. Red-necked grebes nesting in Manitoba had the highest contaminant levels and, assuming that contaminant burdens were accumulated principally on the wintering grounds, the mean PCB:DDE ratio (3.1) indicated that these birds and those from sites in central and eastern Saskatchewan probably wintered on the Atlantic coast. Overall low contaminant levels and a low mean PCB:DDE ratio (1.4) in the eggs of red-necked grebes breeding in Alberta and western Saskatchewan suggested that these birds wintered on the Pacific coast. A similar pattern was apparent in horned and eared grebes. Concentrations of DDE and PCB were both significantly correlated with Ratcliffe index (shell thickness), and were strongly correlated with each other. Ratcliffe indices were determined for historical collections of red-necked grebe eggs. Eggshell thickness of grebes nesting in Manitoba declined significantly during the years following the introduction of DDT (post-1947) and has only recovered partially since it was banned in 1972. The Alberta-breeding population did not appear to have undergone any significant decrease in shell thickness.     

The otter (Lutra lutra) in Sweden--population trends in relation to sigma DDT and total PCB concentrations during 1968-99

Polychlorinated biphenyl (PCB) has been suggested as the major cause of the European otter (Lutra lutra) population decline. This study investigates temporal and geographical changes in otter numbers as well as total PCB and sigma DDT concentrations in otters and their food in different parts of Sweden with various pollution impacts during three decades. In Sweden, rare species belong to the State and carcasses of such specimens are sent to the authorities. Two-hundred and eight specimens have been used to investigate temporal and spatial variation in the otter populations during 1968 and 1999. One-hundred and twenty-five of them have been chemically analysed. The population trends in northern Sweden coincide with the temporal trends of the contaminants. When concentrations of PCBs decrease in the environment, otter population increases. Neither aldrin/dieldrin nor mercury pollution seem to explain why the Swedish otter populations decreased dramatically during the 1960s-1980s. In southern Sweden total PCB concentrations are still high and the indications of improvement of the population are weak.     

Immunohistochemical detection of polychlorinated biphenyls in field collected damselfish (Abudefduf sordidus; Pomacentridae) embryos and larvae

Antibodies against polychlorinated biphenyls (PCBs) were used to determine if immunohistochemical methods could detect PCBs in embryos and larvae of a territorial coral reef fish (Abudefduf sordidus; Pomacentridae) collected from Johnston Atoll, Central Pacific Ocean. Sites with differing levels of contamination were sampled, one with relatively high sediment PCB concentrations of up to 389.0 ng/g and another with low PCB concentrations of only 0.5 ng/g. Immunostaining suggested that PCB concentrations were higher in fish larvae from the PCB contaminated site and that PCB concentrations within abnormal embryos were higher than normal embryos from the same nest. This technique will be useful for detecting exposed populations in the field and assessing correlations with adverse effects, particularly in potential indicator organisms such as Abudefduf sordidus.     

Bald eagle mortality and chlorinated hydrocarbon contaminants in livers from British Columbia, Canada, 1989-1994

Between 1989 and 1994, we obtained 278 carcasses of bald eagles (Haliaeetus leucocephalus) found dead or dying in British Columbia, Canada. All specimens were necropsied and the cause of death determined wherever possible. Livers from a subset of 75 birds were analyzed for polychlorinated biphenyl (PCB) and organochlorine (OC) pesticide residues. A further subset of 19 eagles found dead around the Strait of Georgia, an area of known pulp mill pollution, in summer, and therefore presumably resident birds, were analyzed for polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) and non-ortho PCBs. Liver concentrations ranged from less than 1 to 190 mg/kg for DDE, and up to 72 mg/kg for total PCBs. Concentrations of other OCs were generally less than 1 mg/kg, with the exception of chlordane-related compounds which were occasionally over 2 mg/kg. All birds analyzed for PCDDs and PCDFs contained detectable concentrations of the major 2,3,7,8-substituted isomers. Some birds were very contaminated; one eagle found near a kraft pulp mill site in 1990 contained: 400 ng/kg 2,3,7,8-TCDD, 1400 ng/kg 1,2,3,7,8-PnCDD and 4400 ng/kg 1,2,3,6,7,8-HxCDD. Birds with higher PCB and dichlorodiphenyldichloroethane (DDE) concentrations appeared to weigh less, and there was a significant negative relationship between both PCBs and DDE and numeric scoring of body condition, reflecting the well known process of starvation-induced mobilization of body lipids and contaminants. Birds with higher 2,3,7,8-TCDD concentrations tended to have unusually low concentrations of 2,3,7,8-TCDF, interpreted to indicate hepatic cytochrome P4501A-type induction by TCDD and subsequent metabolism of TCDF.     

Determination of critical pollutant levels in wild populations, examples from organochlorine insecticides in birds of prey

In assessing effects of pollutants on wild organisms, ecological concern is not so much with the protection of individuals, but with the maintenance of self-sustaining populations. Measures of the toxicity of chemicals made under laboratory conditions are thus of limited use when applied to populations in the field. For wild populations the critical level of any pollutant is that level which will lead to population decline (LPD). Among a range of species, this level may bear no consistent relationship to the LD(50) (or LC(50)). In some British birds of prey, whose numbers had been reduced mainly by HEOD poisoning, it was possible to determine the level of HEOD in the birds below which population recovery occurred. For Sparrowhawk and Kestrel, this was equivalent to a geometric mean HEOD level in livers of birds found dead of about 1.0 microg g(-1) (in wet weight). For Peregrines, it was equivalent to a geometric mean HEOD level in addled eggs of 0.7 microg g(-1) (wet weight).     

Trends in organochlorine and mercury levels in Gannet eggs

Levels of DDE, HEOD, PCBs and mercury were measured in Gannet eggs from several colonies around Britain during 1971-1987. At two colonies (Ailsa Craig and Bass Rock) sampled throughout this period, organochlorine levels declined between the early 1970s and 1983, and then increased again. The trends at other colonies, sampled over shorter periods, were generally consistent with those at Ailsa Craig and Bass Rock. Trends in mercury levels were more variable, and increases were observed at four colonies and declines at two. Some shell-thinning occurred in association with DDE contamination. However, levels of this chemical were too low to affect breeding success in the years concerned. The same was probably true of the other chemicals.