ΣDDT Levels Research Articles

Halogenated pollutants in terrestrial and aquatic bird eggs: Converging patterns of pollutant profiles, and impacts and risks from high levels

We investigated the presence, levels, relationships, and risks of HCHs, DDTs, chlordanes, mirex, PCBs, and brominated flame retardants (BFRs) in terrestrial and aquatic bird eggs from an area in South Africa where DDT is used for malaria control. We found one of the highest ΣDDT levels reported this century; 13000ng/gwm (wet mass) in Grey Heron eggs which exceeds critical levels for reproductive success (3000ng/gwm) calculated for Brown Pelicans, with a no-effect level estimated at 500ng/gwm. Even higher ΣDDT levels at 16000ng/gwm were found in House Sparrow eggs (possibly the highest ever recorded for sparrows), with a maximum of 24400ng/gwm. Significant eggshell thinning in Cattle Egrets (33% between thickest and thinnest) was associated with increased levels of p,p′-DDT and p,p′-DDE. There were indications of unknown use of DDT and lindane. Relative to DDT, PCBs and BFRs levels were quite low. Ordinated data showed that different terrestrial pollutant profiles converged to a homogenised aquatic profile. Converging profiles, high levels of DDT in heron and sparrow eggs, and thinning eggs shells, indicate risk and impacts at release, in the aquatic environment, and in between. If characteristic life-strategies of birds in warm areas (e.g. longer-lived and fewer eggs per clutch) increases the risk compared with similar birds living in colder regions when both experience the same environmental pollutant levels, then malaria control using DDT probably has more significant impacts on biota than previously realised. Therefore, risk assessment and modelling without hard data may miss crucial impacts and risks, as the chemical use patterns and ecologies in Africa and elsewhere may differ from the conditions and assumptions of existing risk assessment and modelling parameters. Consideration of other findings associated with DDT from the same area (intersex in fish and urogental birth defects in baby boys), together with the findings of this study (high levels of DDT in bird eggs, eggshell thinning in the Cattle Egrets, and the apparent absence of breeding piscivore birds in the sprayed area) are strongly suggestive of negative impacts from DDT spraying for Malaria control. Our data presents strong arguments for an expedited process of replacing DDT with sustainable methods.

A screening of liver, kidney, and thyroid gland morphology in organochlorine-contaminated glaucous gulls (Larus hyperboreus) from Svalbard

Concentrations of organochlorine (OC) contaminants and histomorphology of liver, kidney, and thyroid tissues were studied in nine adult and one subadult glaucous gulls (Larus hyperboreus) collected at Svalbard on 2 August 2011. Concentrations of liver polychlorinated biphenyls (PCB; range: 150–2820 ng g−1 ww), dichlorodiphenyltrichloroethane (DDT; range: 58–724 ng g−1 ww), and chlordanes (CHL; range: 11–126 ng g−1 ww) dominated the OC profile followed by hexachlorobenzene (HCB; range: 11–42 ng g−1 ww), mirex (range: 2–52 ng g−1 ww), and β-hexachlorocyclohexane (β-HCH; range: 1–7 ng g−1 ww). Histological examination of the liver showed mononuclear cell infiltrations and granulomas in 10 and 6 gulls, respectively, while intense intrahepatic lipid accumulation (steatosis) was found in two and focal necrosis in one gull. In kidney, glomerular sclerosis and adhesions was found in five and one gull, respectively. Thickening of the glomerular basement membranes and tubular necrosis was found in four and seven gulls, respectively, while mononuclear cell infiltrations were found in two individuals. In the thyroid gland, a high density of small follicles accompanied by follicular epithelial cell proliferation was observed in five glaucous gulls. Gulls with hepatic steatosis had significantly higher ΣDDT levels than the gulls without hepatic steatosis and a similar trend was found for ΣPCB. When normalizing OC concentrations for lipid content in liver, gulls with lipid granulomas had significantly lower β-HCH and significantly higher mirex levels, respectively, than gulls without lipid granulomas. Also; gulls with thickening of the glomerular basement membranes had non-significantly higher ΣPCB levels than gulls without. The histological findings were similar to those of controlled laboratory studies and OC-contaminated wildlife (e.g., polar bears; Ursus maritimus) and the data of this study therefore suggest that OC exposure may be a co-factor in the development of organ alterations in glaucous gulls. However, other environmental factors such as age, element exposure, and infectious micropathogens cannot be ruled out as co-factors, and it is uncertain if the tissue changes found exert adverse health effects on the population of Svalbard glaucous gulls.

High levels of DDT in breast milk: Intake, risk, lactation duration, and involvement of gender

We investigated presence and levels of DDT in 163 breast milk samples from four South African villages where, in three of them, malaria is controlled with DDT-sprayed indoors. Mean ΣDDT levels in breast milk were 18, 11, and 9.5 mg/kg mf (milk fat) from the three DDT-sprayed villages, respectively, including the highest ΣDDT level ever reported for breast milk from South Africa (140 mg/kg mf). Understanding the causes for these differences would be informative for exposure reduction intervention. The Provisional Tolerable Daily Intake (PTDI) for DDT by infants, and the Maximum Residue Limit (MRL) were significantly exceeded. DDT had no effect on duration of lactation. There were indications (not significant) from DDT-sprayed villages that first-born female infants drink milk with more ΣDDT than first-born male infants, and vice versa for multipara male and female infants, suggesting gender involvement on levels of DDT in breast milk – requiring further investigation.

Changing patterns of organochlorine pesticide residues in raw bovine milk from Haryana, India

Bovine milk samples were collected and analyzed during 1992 and 1998 from rural areas of 14 different districts of Haryana state for the presence of HCH and DDT residues. The study revealed that the mean residues of ΣHCH in raw bovine milk have declined by 67.5% while mean levels of ΣDDT have decreased by 92.8% during six years gap. The obtained results reveal that during 1992 p,p'-DDT was the main component followed by p,p'-DDD, α-HCH and β-HCH while in 1998, p,p'-DDE and β-HCH followed by p,p'-DDT were relatively more as compared to other isomers and metabolites of these pesticides.

Detection of dicofol and related pesticides in human breast milk from China, Korea and Japan

Previously, we demonstrated that the concentrations of DDTs were greater in breast milk collected from Chinese mothers than from Japanese and Korean mothers. To investigate dicofol as a possible source of the DDTs in human breast milk, we collected breast milk samples from 2007 to 2009 in China (Beijing), Korea (Seoul, Busan) and Japan (Sendai, Takarazuka and Takayama). Using these breast milk samples, we quantified the concentrations of dichlorobenzophenone, a pyrolysis product of dicofol (simply referred to as dicofol hereafter), dichlorodiphenyltrichloroethane and its metabolites (DDTs) using GC–MS. Overall, 12 of 14 pooled breast milk samples from 210 mothers contained detectable levels of dicofol (>0.1 ng g −1 lipid). The geometric mean concentration of dicofol in the Japanese breast milk samples was 0.3 ng g −1 lipid and significantly lower than that in Chinese (9.6 ng g −1 lipid) or Korean breast milk samples (1.9 ng g −1 lipid) ( p < 0.05 for each). Furthermore, the ΣDDT levels in breast milk from China were 10-fold higher than those from Korea and Japan. The present results strongly suggest the presence of extensive emission sources of both dicofol and DDTs in China. However, exposure to dicofol cannot explain the large exposure of Chinese mothers to DDTs because of the trace levels of dicofol in the ΣDDTs. In the present study, dicofol was confirmed to be detectable in human breast milk. This is the first report to identify dicofol in human samples.

Determination of Lead, Cadmium, and Persistent Organic Pollutants in Wild and Orchard-Farm-Grown Fruit in Northeastern Poland

The concentrations of the heavy metals lead (Pb) and cadmium (Cd) were determined in berries (blackberry, raspberry, bilberry, wild strawberry), and hazelnuts picked from plants in the wild as well as in fruit (blackberry, raspberry, blueberry) and hazelnuts picked from orchard-farmed plants in northeastern Poland. The levels of seven congeners of polychlorinated biphenyls (PCB7), γ isomer of hexachlorocyclohexane (γ-HCH), and sum of dichlorodiphenyl trichloroethane and its metabolites (ΣDDT) were also measured in plants and nuts. In addition, the concentrations of Pb, Cd, PCB7, γ-HCH, and ΣDDT were determined in the surface samples of soil from the sites of fruit picking. The highest acceptable concentrations based upon Polish standards for Pb and Cd were not exceeded in forest fruit. In wild berries, Pb occurred at a level below the detection limit, whereas the concentration of Cd ranged from 6 to 49 μg/kg fresh weight. The levels were Cd 72 μg/kg fresh weight and Pb 290 μg/kg fresh weight in raspberries from orchard plants and exceeded the maximal acceptable limit of 50 μg/kg for Cd and 200 μg/kg for Pb. The level of Pb at 210 μg/kg fresh weight in hazelnuts from orchard plants also exceeded maximal acceptable limits. Individual samples of fruit, regardless of their origin, were found to contain trace amounts of organic pollutants such as 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (p,p'–DDE) and PCB congeners 101 and 118. All soil samples contained from 3.2 to 14.9 mg/kg dry weight concentrations of Pb and most soil samples also contained Cd. Further, individual soil samples were found to contain high levels of ΣDDT (145 μg/kg), including p,p'-DDT at a concentration of 67 μg/kg. The concentrations of persistent organic pollutants (POP) in wild and orchard-farm-grown fruit in northeastern Poland were generally below threshold permissible limits, and no correlation was found between levels of contaminants in soils and POP concentrations in fruit.

Trace element and ΣDDT concentrations in horticultural soils from the Tasman, Waikato and Auckland regions of New Zealand

The long-term routine use of agrichemicals can result in elevated levels of trace elements and persistent organic pollutants in soils. Trace element concentrations and ΣDDT levels were measured in soil (0–7.5 cm) samples collected from horticultural and grazing properties in 3 regions of New Zealand (Auckland, Tasman and Waikato). Elevated levels of arsenic (<2 to 58 mg kg − 1 ), cadmium (<0.1 to 1.5 mg kg − 1 ), copper (5 to 523 mg kg − 1 ), lead (5 to 243 mg kg − 1 ) and ΣDDT (<0.03 to 34.5 mg kg − 1 ) were detected in soils from all 3 regions. With the exception of cadmium and zinc, significantly higher levels of contaminants were generally detected in horticultural soils than in grazing soils. Our results have implications for the on-going use of agrichemicals as concentrations of cadmium, copper, tin and zinc in some samples exceeded ecotoxicity based soil criteria. The p, p′-DDE : DDT ratios indicate that the degradation of DDT in NZ horticultural soils may be inhibited by the co-contamination with trace elements.

Toxaphene and other persistent organochlorine pesticides in three species of albatrosses from the north and south Pacific Ocean

AbstractToxaphene and other persistent organochlorine (OC) pesticides (chlordane‐related compounds [ΣCHL], DDT‐related compounds [ΣDDT], hexachlorocyclohexanes [ΣHCH], tris(p‐chloro‐phenyl)methane, hexachlorobenzene, octachlorostyrene, dieldrin) were determined in fat of Laysan albatross (Diomedea immutabilis) and in fat and eggs of blackfooted albatross (Diomedea nigripes) from the central north Pacific Ocean. The HCH isomers and chlordane‐ and DDT‐related compounds were also determined in eggs of northern royal albatross (Diomedea sanfordi) collected in New Zealand. Toxaphene was detected in fat samples at mean ± standard deviation (SD) levels ranging from 243 ± 61 ng/g wet weight in Laysan albatross to 1,020 ± 237 ng/g wet weight in blackfooted albatross. These levels were higher than ΣCHL and ΣHCH but lower than ΣDDT. In eggs of blackfooted albatross, toxaphene was the major OC pesticide, averaging 513 ng/g wet weight in two pooled samples compared with 293 ng/g wet weight for ΣDDT. Two toxaphene congeners, the octachloroborane B8–1413 (Parlar 26) and the nonachlorobornane B9–1679 (P50), comprised about 38% of total toxaphene in both albatross species. All OC compounds were present at significantly higher levels in blackfooted than Laysan albatross fat with the exception of ΣHCH, dieldrin, and octachlorostyrene. Mean levels of ΣDDT and ΣHCH in northern royal albatross eggs from New Zealand were 4 and 60 times lower, respectively, than in blackfooted albatross eggs. The pattern of OC pesticide accumulation was consistent with differences in distribution of the three species in the Pacific Ocean, with highest levels in blackfooted albatross, which feed off the west coast of North America, intermediate levels in Laysan albatross, which frequent the western Pacific, and lowest levels in northern royal albatross, which are confined to the southern oceans surrounding the Antarctic.

Historical contamination of Yukon Lake sediments by PCBs and organochlorine pesticides: influence of local sources and watershed characteristics

PCBs and other persistent organochlorine (OC) pesticides were analyzed in sediment cores collected from six lakes in Yukon Territory and one in northern British Columbia, Canada, with the objective of establishing sources and historical trends of these contaminants. DDT was found to be the most prominent OC in the sediment profiles of most of the lakes. Maximum ΣDDT levels (3.47–2680 ng g −1 dw) were observed in sediment slices dated to the 1950s from lakes near populated areas. In contrast, in more remote lakes (Hanson, Kusawa and Lindeman), the maximum ΣDDT concentrations were observed in the sediments dated to the 1970s. Highest ΣPCB and ΣDDT concentrations were measured in sediments from Watson Lake, near a suspected PCB waste disposal site and in a region where DDT was heavily applied in the 1950s and 1960s. Elevated ΣPCB concentrations [16.1–93.6 ng g −1 dry weight (dw)] were also observed in sediments from lakes situated near populated areas, relative to Kusawa and Lindeman (11.1 and 12.7 ng g −1 dw, respectively). Recent ΣPCB fluxes ranged from 621 ng m −2 y −1 in Kusawa Lake to 16 400 ng m −2 y −1 in Little Atlin Lake. The extremely high sedimentation rate (2050 g m −2 y −1) in glacial fed Lindeman Lake gave rise to elevated fluxes of ΣPCB (2410 ng m −2 y −1) and other OCs, despite much lower concentrations in the sediment. Levels of hexachlorocyclohexanes (ΣHCH), chlordane-related compounds (ΣCHL), and chlorobenzenes (ΣCBz) were in the low ng g −1 (dw) range in all lake sediments, similar to concentrations previously reported for Arctic lakes in Canada, indicating that their major source was long range atmospheric transport. Contamination of the lakes with PCBs and DDT near populated areas of the Yukon Territory appears to be a result of regional activities rather than long range transport and deposition. The results also point to glacial runoff as a significant source of OCs to small, high elevation lakes (Lindeman), but not to larger lakes within the Yukon River drainage basin that are also affected by glacial sources (Kusawa, Laberge).

Temporal and biogeographic comparisons of PCBs and persistent organochlorine pollutants in the blubber of fin whales from eastern Canada in 1971–1991

Concentrations of PCB congeners and organochlorine (OC) pesticides were studied in archived fin whale ( Balaenoptera physalus) blubber samples collected in 1971–1972 from Newfoundland (Nfld) and Nova Scotia (NS) with the objective of obtaining a historical perspective on contaminant levels and proportions at a time when many persistent OCs were still in use. Concentrations of ΣPCBs and ΣDDTs in the blubber of 17 fin whales from historical whaling stations in 1971–1972 were generally in agreement with previously reported values for fin whales from Atlantic Canada. Although some differences in sex and body length (age) distribution of samples occurred, significant differences were detected in the concentrations and patterns of PCBs, DDTs and chlordanes in whales from Nfld and NS, supporting ecological evidence that whales from these regions represent relatively separate stocks. Temporal and geographical variations were examined by comparing data to those reported for fin whales from the St Lawrence Estuary (StL) in 1991 by Gauthier et al. (1997a). Significantly higher levels of ΣDDT, ΣCHL and HCB were found in the NS (1971–1972) stock compared with the StL (1991) animals, and in HCB between the Nfld stock (1971–1972) and the StL (1991) animals, as well as higher p,p′-DDE/ΣDDT and lower p,p′-DDT/ΣDDT ratios in the 1991 whales suggesting that temporal trends in these whales between the 1970s and 1990s were consistent with those in other marine mammals in Atlantic Canada. Evidence also suggests that geographical variations in patterns may occur for individuals from two relatively distinct stocks of fin whales in Atlantic Canada (NS, Nfld) and perhaps for one population (StL) related to, but recognisably different from the NS stock.

Patterns and Levels of Organochlorines (DDTs, PCBs, non-ortho PCBs and PCDD/Fs) in Male Harbour Porpoises (Phocoena phocoena) from the Baltic Sea, the Kattegat-Skagerrak Seas and the West Coast of Norway

Patterns and levels of chlorinated aromatic contaminants (DDTs, PCBs, non-ortho PCBs and PCDD/Fs) in blubber tissue were compared among six sample groups of male harbour porpoises (Phocoena phocoena) from the Baltic Sea, the Kattegat-Skagerrak Seas and the west coast of Norway. A principal component and classification analysis showed that mature harbour porpoises from the Baltic had significantly different contaminant patterns than animals from the Kattegat-Skagerrak and Norway. ANOVAs showed that mature porpoises from the Baltic had higher levels of ΣPCB and several individual PCBs and PCDD/Fs than the Kattegat-Skagerrak and the Norwegian samples and higher ΣDDT than the Norwegian. A comparison between immature porpoises showed that Baltic animals had higher levels of ΣPCDD/F than the corresponding sample from the Kattegat-Skagerrak. The levels of ΣDDT, ΣPCB and Σnon-ortho PCB were significantly higher in animals collected during 1978–81 compared to animals collected in 1988–90 indicating a temporal decline of these organochlorines in the Kattegat-Skagerrak Seas. The contaminant levels recorded in the Baltic Sea are a serious cause for concern and could have management implications for the already threatened harbour porpoises in this area.

DDT group compounds in fish and shellfish from the Mersey Estuary and Liverpool Bay

Concentrations of ΣDDT, reported as Σop′ and pp′ DDT, DDD, and DDE, in muscle tissue of fish from the Mersey Estuary are significantly elevated, compared to outer Liverpool Bay and the Irish Sea. ΣDDT concentrations in Mersey Estuary fish, especially flounder, are also higher than for populations of the same species in the Thames Estuary, the west of Scotland, the English Channel, and Atlantic coast estuaries of France. ΣDDT was especially high in flounder from Garston in the inner Mersey Estuary (38.4 ± 17 μg kg−1 wet wt), but were also elevated in plaice, Dover sole, dab, and invertebrates. ΣDDT is dominated by pp′DDD and pp′DDE, and the former makes an unusually high contribution (44–65%) to ΣDDT compared to sites elsewhere. Concentrations of pp′DDT are measurable in Mersey Estuary fish but generally only at low levels. Cod and whiting contained much lower levels of ΣDDT than flatfish. Residues of DDT in whitefish from Liverpool Bay are similar to those for the Solway Firth and Arctic waters and generally below 3 μg kg−1 wet weight. ©1997 by John Wiley & Sons, Inc. Environ Toxicol Water Qual 12: 223–229, 1997

Effects of environmental pollution on breeding populations of birds in southern Poland

Breeding performance of Great tit (Parus major) was studied in two forests in southern Poland, in the districts of Cracow and Katowice, and in a Swedish reference area. Concentrations of Cd, Cu, Fe, Pb, Zn, methyl Hg, ΣDDT, and ΣPCB in tissues of nestlings, were monitored. The birds′ tissue concentrations of the nonessential elements, Cd and Pb, were elevated at the Polish localities, and reflected the degree of environmental contamination. ΣDDT levels were higher in the Polish birds than in the Swedish. Breeding results of the birds were severely affected in southern Poland, and high frequencies of the fledged young showed low Hb.

PCBs and other organochlorines in human tissue samples from the Welsh population: I—adipose

The general exposure of humans to polychlorinated biphenyls (PCBs) and ΣDDT (i.e., p, p′-DDT + p, p′-DDE + p, p′-DDD) in Wales (UK) was determined through the analysis of adipose tissue samples collected from 75 individuals during post-mortem examinations in 1990–1991. Fifty PCB congeners were screened, of which 29 were identified in most of the samples. Congener IUPAC numbers 138, 153 and 180 were the most abundant compounds, accounting for an average of 55% of the ΣPCB congeners analysed. ΣPCB concentrations varied between 0·2 and 1·8 μg g −1 of adipose tissue and were positively correlated with the donors age and negatively associated with the percentage of lipid in the adipose tissue. A progressive change in the congener pattern was noted with increasing subject age. Tissue from older individuals generally contained a relatively high proportion of the more persistent and higher chlorinated congeners. ΣDDT concentrations ranged from 0·11 to 5·6 μg g −1 adipose tissue, with p, p′-DDE contributing 96% towards the ΣDDT concentration. ΣDDT levels were also positively correlated with age. No significant differences in the ΣPCB and ΣDDT concentrations were noted between males and females, between people living in rural and urban locations or with the subjects' body weight at the time of their death.

PCBs and other organochlorines in human tissue samples from the Welsh population: II—milk

Polychlorinated biphenyl (PCB) and ΣDDT (i.e. p,p′- DDT + p,p′- DDE + p,p′ DDD) concentrations were determined from the analysis of 115 Welsh breast milk samples collected in 1990 and 1991. Fifty PCB congeners were screened, of which 24 were identified in most samples. The PCB congener pattern was consistent between individual milk samples, with IUPAC congeners 28, 138, 153 and 180 being the most abundant and accounting for an average of 50% of the ΣPCB concentrations determined. PCB concentrations varied between 2 and 70 ng g −1 whole milk, were positively correlated with age, and negatively correlated with the total lactation period and with the percent lipid content of the milk. PCB pattern distributions differed between milk and adipose tissue samples. Human milk had a higher proportion of tri- (18 and 28), tetra- (44, 52 and 66) and pentachlorinated biphenyls (101) compared to human adipose tissue. ΣDDT concentrations ranged from 0·3 to 71 ng g −1 of whole milk, with p,p′- DDE contributing towards an average of 92% of the ΣDDT concentrations. ΣDDT levels were also positively correlated with age and negatively associated with the lactation period, though these correlations were rather weak. No significant differences in the ΣPCB and ΣDDT concentrations were noted between milk samples from donors living in rural and urban locations, or between the subjects' body weight, smoking habits or diet.

Organochlorine pesticide residues in human milk in Punjab, India

Human milk samples collected from areas having intensive cotton cultivation and sparce cotton cultivation in Punjab (India) were analysed for organochlorine insecticides. Both DDT and HCH were detected in almost all the samples analysed. The average levels of Σ-DDT and Σ-HCH residues in samples from cotton-growing areas were significantly higher than in those from areas where cotton is sparsely grown. Residues of Σ-DDT mainly comprised p, p′-DDT and p, p′-DDE, while those of Σ-HCH residues were mainly in the form of its β-isomer. Median values of 0·52 μg g −1 of Σ-DDT and 0·19 μg g −1 of Σ-HCH in samples of human milk from cotton-growing areas of Punjab (India) were higher than those reported from most other countries in the World.

Organochlorines, including chlordane compounds and their metabolites, in peregrine-falcon, prairie-falcon, and clapper-rail eggs from the USA

Four compounds present in technical chlordane ( trans- and cis-nonachlor, and tentatively MC-2 and MC-5) and three metabolites of chlordane (heptachlor epoxide, oxychlordane, and U-4) were identified by GC/MS in peregrine-falcon ( Falco peregrinus anatum) eggs. Levels of Heptachlor epoxide, oxychlordane, trans- and cis-chlordane, trans- and cis-nonachlor, MC-2, and MC-5 were quantified by GC/ECD in peregrine-falcon eggs from the US east coast, Colorado, and California; and in prairie-falcon ( Falco mexicanus) and light-footed-clapper-rail ( Rallus longirostris levipes) eggs from California. The eggs were collected between 1986 and 1989. Oxychlordane, heptachlor epoxide, trans- and cis-nonachlor, MC-2, and MC-5 were detected in every egg analyzed. Heptachlor, trans-, and cis-chlordane were either not detected, or present at low levels in the eggs. The highest Σchlordane levels were found in the East Coast peregrine-falcon eggs at a geometric mean (geom. mean) concentrations of 1800 μg/kg (ppb); the lowest levels of Σchlordane were found in the prairie-falcon eggs at a concentration of 120 μg/kg (geom. mean). Of the technical chlordane compounds measured, MC-2 bioaccumulated to the greatest degree. ΣDDT levels in the falcons ranged from 11 000 μg/kg (geom. mean) in the Colorado samples to 8800 μg/kg (geom. mean) in the East Coast and California peregrines. ΣDDT levels in the rail eggs were 3000 μg/kg (geom. mean). The highest ΣPCB levels were found in the East Coast peregrine-falcon eggs at a concentration of 14 000 μg/kg (geom. mean); the lowest levels of ΣPCB were found in the prairie-falcon eggs at a concentration of 350 μg/kg (geom. mean).

Effects of DDT on the Fish Eagle Haliaeetus vocifer population of Lake Kariba in Zimbabwe

Twenty clutches were collected from nests of Fish Eagles Haliaeetus vocifer at Lake Kariba, Zimbabwe, and a small dam nearby in 1989‐90. Unaltered DDT, and metabolites DDD and DDE, were found in every egg. Mean levels of σDDT(= DDT + DDD + DDE) generally varied from 14 to 49 mg/kg dry weight per clutch, but 113–223 mg/kg dry weight were found in clutches from the eastern end of the lake and the mouth of the Sengwa River. SDDT and DDE levels were significantly correlated with the Ratcliffe Index of eggshell thickness. Comparison with museum specimens showed that the Ratcliffe Index has declined by 11% since 1936‐41 due to a significant fall in shell weight. Eggshell thinning exceeded 20% at the eastern end of the lake.Aerial surveys in 1987 and 1990 found that hatching success along the southern lakeshore exceeded 72%, but chicks were seen in fewer than half the nests at the eastern end. However, the density of breeding pairs was greatest here.Residue levels have increased by about 8% since 1980, rising more steeply in areas recently sprayed for tsetse fly control and falling in others. The threat from DDT may now be receding as regional use has declined and will end, for tsetse fly control, by 1995. None was used for this purpose in 1991. Mercury levels in adult birds were very high and may pose a significant risk.The breeding population may be limited by availability of safe nest sites. Chicks are sometimes eaten by people. Settlement along the lakeshore is increasing and safe sites are becoming scarcer as dead trees in the lake collapse and large trees onshore are destroyed by elephants.

Organochlorine pesticide and polychlorinated biphenyl residues in foodstuffs from Bangkok, Thailand

Raw foodstuffs collected from Bangkok, Thailand, were analysed for the presence of PCBs, DDTs, HCHs (BHCs). HCB, aldrin, dieldrin, heptachlor and heptachlor epoxide. Residues of PCBs and organochlorine pesticides were detected in all the samples analysed. Concentrations of PCBs did not reach the tolerance limit set forth by the US Food and Drug Administration (FDA). The concentrations of ΣHCH were higher than those of ΣDDT in all the farm products while the levels of ΣDDT were greater in fishes including fish flakes and fishmeal. Meat samples recorded higher concentrations of ΣDDT and dieldrin than ΣHCH. Comparing the levels of organochlorines in foodstuffs from Bangkok, considerable levels of aldrin and dieldrin indicate the need for concern from the food safety point of view because of their much higher toxicity than DDT and other organochlorines. However, the levels did not exceed the Maximum Residue Limit (MRL) recommended by FAO/WHO. Food contamination by HCB, heptachlor and heptachlor epoxide is comparatively lower.

Spatial differences and temporal trends of organochlorine compounds in biota from the northwestern hemisphere

Tissues of animal species from various trophic levels in the northwestern hemisphere were collected and analyzed for the presence of polychlorinated camphenes (PCC,e.g. toxaphene), DDT and its metabolites DDD and DDE (σDDT) and polychlorinated biphenyls (PCB) to elucidate differences in geographical distribution, biomagnification and temporal trends. Many of the samples were also analyzed for the presence of chlordane. The previously achieved knowledge of DDT and PCB contamination was used as a yardstick for characterizing the exposure regime of the other organochlorine compounds. No pronounced geographical differences were found for PCC when comparing animals from the Arctic region with corresponding species in the Baltic, while both PCB and σDDT showed definite spatial differences. The highest concentrations of σDDT and PCB were found in fish predators,i.e., raptorial birds and seals, from the Baltic. PCC levels in fish exceed levels of σDDT and PCB in the North Atlantic and the PCC levels in Swedish fish are as high as or higher than the σDDT levels. While the σDDT and PCB levels for all trophic levels range from 0.14–990 mg/kg fat, the corresponding range for PCC is only 0.33–17 mg/kg. This indicates less biomagnification of PCC and/or a more effective metabolism of PCC, compared with σDDT and PCB, at high trophic levels. The levels of σDDT and PCB in Swedish fish and birds show a decrease during the late seventies and the beginning of the eighties. For the PCC levels, however, no distinct trends could be discerned during the same period in any of the areas studied.