Levels Of Hexachlorobenzene Research Articles

Reproductive outcomes of maternal contamination with Cyclodiene insecticides, Hexachlorobenzene and β-Benzene Hexachloride

The effects of organochlorines on human reproduction have been recently under scrutiny. Some negative effects on animal reproduction have been reported. In this study we aimed to evaluate the effect of maternal contamination with a certain group of organochlorines, which are cyclodienes, HCB (hexachlorobenzene) and β-BHC (beta-hexachlorocyclohexane) on human reproduction. Breast milk samples from 815 eligible Victorian mothers were used for measuring maternal contamination and the reproductive outcomes such as birth weight, head circumference and prematurity were taken from health files.Our study did not show any significant negative effect on outcomes such as birth weight, small for gestation age, previous miscarriage or still birth, head circumference or sex ratio. An inconsistent increase across oxychlordane exposure levels for prematurity was found. We also found an inverse association between the highest levels of HCB and oxychlordane with previous miscarriage or still birth; but this was based on small numbers and may be explained by loss of contaminants through the aborted fetus. These results suggest that the declining contamination levels of these chemicals do not impose a threat to human reproduction.

Organochlorines in Antarctic and Arctic Avian Top Predators: A Comparison between the South Polar Skua and Two Species of Northern Hemisphere Gulls

Different organochlorine compounds (OCs) were measured in the blood of breeding south polar skuas (Catharacta maccormicki) at Svarthamaren, Dronning Maud Land (Antarctica) and compared to those in two species of northern hemisphere gulls: the Arctic glaucous gull (Larus hyperboreus) and the subarctic great black-backed gull (Larus marinus). The skuas had 8% and 29% of the SigmaOC levels (45 ng/g, wet weight) of glaucous gulls (591 ng/g) and great black-backed gulls (158 ng/g), respectively. Polychlorinated biphenyls (PCBs) and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) were very low in skuas compared to northern gulls, but the mean hexachlorobenzene (HCB) level was 1.7 times higher than in great black-backed gulls and one-third of the glaucous gull level. Mirex levels in skuas were among the highest reported in birds, the mean level being 3 and 26 times higher than those in glaucous gull and great black-backed gulls, respectively. In skuas, the mean levels of HCB, oxychlordane, p,p'-DDE, and PCBs increased by about 30% during a 2-week period, and mirex increased by nearly 60%. In glacuous gulls, HCB, p,p'-DDE, and PCBs increased by 10-20%. For HCB, mirex, and oxychlordane, only a relatively small proportion of the increase in skuas could be explained by changes in lipid pools and the levels at first sampling, compared to glaucous gulls. Thus, skuas were probably accumulating these compounds when present in Antarctica. p,p'-DDE and PCB levels, in contrast, seemed much more stable in the skuas. Relatively high levels of mirex and HCB in south polar skuas are concerning with regard to potential adverse effects.

Effects of hexachlorobenzene on antioxidant status of liver and brain of common carp ( Cyprinus carpio)

Hexachlorobenzene (HCB)-induced oxidative damages have been published in rats while the effects have not yet been reported in fishes. Juvenile common carps ( Cyprinus carpio) were exposed to waterborne HCB from 2 to 200 μg l −1 for 5, 10 or 20 days. Liver and brain were analyzed for various parameters of oxidative stress. There were no significant changes of glutathione (GSH) content and superoxide dismutase (SOD) activity in liver after 5 or 10 days exposure, whereas obvious drops were observed at higher concentrations after 20 days exposure. Significant decreases of GSH content and SOD activity in brain were found during all the exposure days. In brain, HCB also significantly elevated the contents of reactive oxygen species (ROS), thiobarbituric acid- reactive substances (TBARS, as an indicator of lipid peroxidation products), glutathione disulfide (GSSG), and activities of nitric oxide synthase (NOS), glutathione peroxidase (GPx), and glutathione reductase (GR), and inhibited activities of acetylcholinesterase (AchE) and glutathione S-transferase (GST). The results clearly demonstrated that environmentally possible level of HCB could result in oxidative stress in fish and brain was a sensitive target organ of HCB toxicity.

Association of In Utero Organochlorine Pesticide Exposure and Fetal Growth and Length of Gestation in an Agricultural Population

From 1940 through the 1970s, organochlorine compounds were widely used as insecticides in the United States. Thereafter, their use was severely restricted after recognition of their persistence in the environment, their toxicity in animals, and their potential for endocrine disruption. Although substantial evidence exists for the fetal toxicity of organochlorines in animals, information on human reproductive effects is conflicting. We investigated whether infants’ length of gestation, birth weight, and crown–heel length were associated with maternal serum levels of 11 different organochlorine pesticides: p,p′-dichlorodiphenyltrichloroethane (p,p′-DDT), p,p′-dichlorodiphenyldichloroethylene (p,p′-DDE), o,p′-dichlorodiphenyltrichloroethane (o,p′-DDT), hexachlorobenzene (HCB), β-hexachlorocyclohexane (β-HCCH), γ-hexachlorocyclohexane (γ-HCCH), dieldrin, heptachlor epoxide, oxychlordane, trans-nonachlor, and mirex. Our subjects were a birth cohort of 385 low-income Latinas living in the Salinas Valley, an agricultural community in California. We observed no adverse associations between maternal serum organochlorine levels and birth weight or crown–heel length. We found decreased length of gestation with increasing levels of lipid-adjusted HCB (adjusted β= −0.47 weeks; p = 0.05). We did not find reductions in gestational duration associated with any of the other organochlorine pesticides. Our finding of decreased length of gestation related to HCB does not seem to have had clinical implications for this population, given its relatively low rate of preterm delivery (6.5%).

Brominated flame retardants and organochlorine pollutants in aquatic and terrestrial predatory birds of Belgium: levels, patterns, tissue distribution and condition factors

Liver and muscle samples from 7 species of aquatic and terrestrial predatory birds from Flanders (Belgium) were analysed for polychlorinated biphenyls (PCBs), polybrominated diphenylethers (PBDEs) and organochlorine pesticides (OCPs). PCBs were the predominant compounds in our samples, which showed highest concentrations in the liver of barn owl ( Tyto alba) and sparrowhawk ( Accipiter nisus) (up to 1000 μg/g lipid weight). PBDEs could be determined in most samples at lower concentrations than PCBs (up to 64 μg/g lipid in sparrowhawk liver). Sparrowhawks had the highest levels of hexachlorobenzene, DDTs and PBDEs. In contrast, kestrels ( Falco tinnunculus) had relatively low levels of most measured organochlorines. BDE 47 was the most abundant congener in heron ( Ardea cinerea) and grebe ( Podiceps cristatus), while BDE 47, 99 and 153 were equally important in the terrestrial species. BDE 183 and BDE 209 were only measured in the terrestrial birds. These results indicate that terrestrial birds may be more exposed to higher brominated BDE congeners than aquatic species.

Relationship of Lead, Mercury, Mirex, Dichlorodiphenyldichloroethylene, Hexachlorobenzene, and Polychlorinated Biphenyls to Timing of Menarche Among Akwesasne Mohawk Girls

Relationship of Lead, Mercury, Mirex, Dichlorodiphenyldichloroethylene, Hexachlorobenzene, and Polychlorinated Biphenyls to Timing of Menarche Among Akwesasne Mohawk Girls

A Worldwide Survey of Polychlorinated Dibenzo-p-dioxins, Dibenzofurans, and Related Contaminants in Butter

The main source of human exposure to persistent organic pollutants (POPs) is, in general, food. In this study, 64 butter samples from 37 countries were analyzed to assess the global contamination of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs), hexachlorobenzene (HCB), and 2,2-bis (4-chlorophenyl)-1,1,1-trichloroethane (DDT) together with its major metabolites. The objectives of the study were to assess the presence of major organohalogen contaminants in butter, to trace geographical differences, and to determine toxic equivalents (TEQs) of PCDDs/Fs and dioxin-like PCBs in butter. The highest PCDD/F concentrations were found in butter from Korea with an average of 1.4 pg TEQ g(-1) lipid weight (l.w.). from PCDD/F and an additional contribution from the non- and mono-ortho-PCBs of 0.55 pg TEQ g(-1) l.w. Belgian butter showed average levels of 0.53 and 1.2 pg TEQ g(-1) l.w. for PCDDs/Fs and PCBs, respectively, but one sample of Belgium butter had a total TEQ level as high as 4.0 pg TEQ g(-1) l.w. Three out of five butter samples from Portugal showed similarly high PCDD/F TEQ levels. The sigmaPCB levels in European butter appeared to be somewhat higher than in the samples from the rest of the world. The average contribution of CB-153 to the total PCB concentration was 22% (SD 6.4, coefficient of variation 29%). Generally, the PCBs contributed around 60% of the total TEQ value, with CB-126 contributing approximately half of this value. This shows the important TEQ contribution from dioxinlike PCBs to the total TEQs. The highest HCB levels were found in butter samples from Russia, Ukraine, Belgium, and Slovenia. Low levels of HCB in butter were generally found in the Southern Hemisphere. Butter samples from countries from Eastern Europe had elevated sigmaDDT concentrations, with a particularly high concentration in Ukraine butter, followed by some Russian samples, Brazil, and the U.S.

Atmospheric Concentrations and Air−Water Flux of Organochlorine Pesticides along the Western Antarctic Peninsula

Air, seawater, sea ice, and snow were collected during the austral winter (September-October 2001) and summer (January-February 2002) along the Western Antarctic Peninsula. Hexachlorobenzene (HCB) > heptachlor > alpha- and gamma-hexachlorocyclohexane (HCH) and heptachlor epoxide, were the most frequently detected organochlorine pesticides in air. HCB and HCH levels declined over the past 20 years, with a half-life of 3 years for sigmaHCH in Antarctic air. However, heptachlor epoxide levels have not declined in Antarctic air over the past decade, possibly due to continued use of heptachlor in the southern hemisphere. Peak heptachlor concentrations in air were measured coincident with air masses moving into the region from lower latitudes. Levels of lindane were 1.2-200 times higher in annual sea ice and snow compared to alpha-HCH, likely due to greater atmospheric input of gamma-HCH. The ratio of alpha/gamma-HCH in Antarctic air, sea ice and snow was <1, illustrative of a predominance of influx of lindane versus technical HCH to the regional environment. However, alpha/gamma-HCH in seawater was >1, likely due to more rapid microbial degradation of gamma- versus alpha-HCH. Water/air fugacity ratios for HCHs demonstrate continued atmospheric influx of HCHs to coastal Antarctic seas, particularly during late summer.

Persistent organic pollutants in edible marine species from the Gulf of Naples, Southern Italy

Edible tissues from 10 marine species, collected from the Gulf of Naples in the Southern Tyrrhenian Sea (Italy) between February and July 2003, were analysed for the presence of organochlorine pesticides hexachlorobenzene (HCB) and DDTs ( p, p′-DDT, p, p′-DDE, and p, p′-DDD), and 20 polychlorinated biphenyls (PCBs). The PCB levels (calculated as the sum of all the determined congeners) were found to be the highest (from 56.8 to 47909.5 ng/g on lipid basis), followed by the DDTs (sum of p, p′-DDT and its metabolites; <dl–2095.5 ng/g) and HCB (<dl–165.4 ng/g). There were marked differences in residue levels of DDTs and PCBs among the various species under investigation (from P<0.05 to P<0.001). Since the presence of organochlorine pollutants was most evident in the strictly resident species which inhabit shallow coastal waters, contamination of the Gulf of Naples by these compounds probably derives from local agricultural, industrial, and municipal sources. Concentrations of DDTs and PCBs detected in this study were generally comparable or higher than those found in studies of similar species from other Mediterranean and non-Mediterranean regions subject to a high anthropogenic impact. From the human health point of view, the residue levels of HCB and DDTs detected in this study are well below the Maximum Residue Limits for some foods of animal origin (0.2 and 1 mg/kg fat weight for HCB and DDTs calculated as the sum of p, p′-DDT, p, p′-DDE, p, p′-DDD, and o, p′-DDT, respectively). However, the concentrations of PCBs (calculated as the sum of the seven “target” congeners IUPAC nos. 28, 52, 101, 118, 138, 153, and 180) detected in all the analysed samples far exceed the action limit of 200 ng/g fat weight recommended by the European Union for eggs, fresh pig meat, fresh poultry meat, and derived products.

Evaluation of the concentration of HCH, DDT, HCB, PCB and PAH in the sediments along the lower stretch of Hugli estuary, West Bengal, northeast India

Detailed analyses of persistent organic pollutants (POPs) such as hexachlorocyclohexane (HCH) isomers (HCHs), dichlorodiphenyltrichloro ethane (DDT) and its metabolites (DDTs), hexachlorobenzene (HCB) and congeners of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in surface sediments from the coastal estuarine environment of West Bengal, northeast India allowed the evaluation of the contamination status, distribution and possible pollution sources. HCH, DDT, HCB, PCB and PAH were identified compounds in all the samples, whereas the concentrations of chlorinated pesticides (trans-eptachlorepoxide, dieldrin, endrin, metaoxychlor and mirex) were below the detection limits and were not of great concern. The pesticides did demonstrate markedly different distributions reflecting different agricultural and domestic usage in the region. The range of concentrations of HCH, HCB, DDT and PCBs in the sediments were 0.11–0.40, <0.05–0.98, 0.18–1.93 and 0.18–2.33 ng/g dry wt, respectively. Overall elevated levels of HCB, DDT and PCB were recorded at Babughat, a very closely located site of the metropolitan megacity Calcutta. Fluoranthene (flu) and pyrene (py), the dominant 4-ring PAHs, also showed an abrupt elevated concentrations at Babughat with values of 214 and 144 ng/g dry wt, respectively. Among the isomers and metabolites of HCH, DDT and PCB, α-HCH, pp′-DDT and PCB 101, PCB 118, PCB 153 and PCB 138 were found to be dominant. High ratios of metabolites of DDT to ΣDDTs reveal recent use of DDT in this coastal environment. Fluoranthene, pyrene, 1,2-benzo(a)anthracene and chrysene formed the dominant congeners out of 19 identified PAHs. The sources of contamination are closely related to human activities such as domestic and industrial discharge, automobile exhausts, street runoff, slum sewage, agricultural chemicals and soil erosion due to deforestation as well as atmospheric transport. This study is compared to other coastal and estuarine environments in India and abroad. The baseline data can be used for regular ecological monitoring, considering the industrial and agricultural growth around this important estuarine ecosystem.

Determination of organochlorine pesticide residues in honey from the central zone of Portugal and the Valencian community of Spain☆

In this study nine organochlorine pesticide residues (α-, β-, and γ-hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), aldrin, p , p ′-DDE, p , p ′-DDD, o , p ′-DDT, and p , p ′-DDT) in forty nine samples of honey collected from markets of Portugal and Spain during 2001 and 2002, respectively, were evaluated. For this evaluation, three analytical procedures were studied. The analytical procedure, based on LLE extraction with ethyl acetate followed by gas chromatography–electron-capture detection (GC–ECD) for quantification, and mass spectrometry (GC–MS) for confirmation, has been selected. Recoveries of spiked samples ranged from 68%, for β-HCH, and 126% for p , p ′-DDT, for fortification levels between 10 and 100 μg/kg, and 64%, for α-HCH, and 143% for γ-HCH for fortification levels between 20 and 200 μg/kg. Limits of quantification, using GC–ECD, were from 0.01 and 0.10 mg/kg, and limits of detection between 0.001 and 0.02 mg/kg. Fourteen Valencian samples were contaminated, containing residues of HCB or/and HCH isomers. The frequency of detection was 56% for Spanish samples. In Portugal, 23 samples were contaminated, what means 95.8%. In Spanish samples, concentrations range from nd to 0.03 mg/kg for HCB, and nd to 2.24 mg/kg for HCH-total. The mean concentration and standard deviation were 0.017 ± 0.011 mg/kg for HCB, and 0.579 ± 0.747 mg/kg for HCH-total, contributing the γ isomer with the highest values. The samples from Portugal showed higher levels. Levels of HCB ranged from nd to 0.39 mg/kg. HCH-total ranged from nd to 4.86 mg/kg, and DDT-total from nd to 0.658 mg/kg. Mean concentration and standard deviation were 0.09 ± 0.116 mg/kg for HCB, 1.357 ± 1.30 mg/kg for HCH-total, and 0.143 ± 0.193 mg/kg for DDT-total.

Determination of organochlorine pesticide residues in honey from the central zone of Portugal and the Valencian community of Spain

In this study nine organochlorine pesticide residues (α-, β-, and γ-hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), aldrin, p, p′-DDE, p, p′-DDD, o, p′-DDT, and p, p′-DDT) in forty nine samples of honey collected from markets of Portugal and Spain during 2001 and 2002, respectively, were evaluated. For this evaluation, three analytical procedures were studied. The analytical procedure, based on LLE extraction with ethyl acetate followed by gas chromatography–electron-capture detection (GC–ECD) for quantification, and mass spectrometry (GC–MS) for confirmation, has been selected. Recoveries of spiked samples ranged from 68%, for β-HCH, and 126% for p, p′-DDT, for fortification levels between 10 and 100 μg/kg, and 64%, for α-HCH, and 143% for γ-HCH for fortification levels between 20 and 200 μg/kg. Limits of quantification, using GC–ECD, were from 0.01 and 0.10 mg/kg, and limits of detection between 0.001 and 0.02 mg/kg. Fourteen Valencian samples were contaminated, containing residues of HCB or/and HCH isomers. The frequency of detection was 56% for Spanish samples. In Portugal, 23 samples were contaminated, what means 95.8%. In Spanish samples, concentrations range from nd to 0.03 mg/kg for HCB, and nd to 2.24 mg/kg for HCH-total. The mean concentration and standard deviation were 0.017 ± 0.011 mg/kg for HCB, and 0.579 ± 0.747 mg/kg for HCH-total, contributing the γ isomer with the highest values. The samples from Portugal showed higher levels. Levels of HCB ranged from nd to 0.39 mg/kg. HCH-total ranged from nd to 4.86 mg/kg, and DDT-total from nd to 0.658 mg/kg. Mean concentration and standard deviation were 0.09 ± 0.116 mg/kg for HCB, 1.357 ± 1.30 mg/kg for HCH-total, and 0.143 ± 0.193 mg/kg for DDT-total.

Breastfeeding and concentrations of HCB and p,p′-DDE at the age of 1 year

Exposure to organochlorine compounds (OCs) occurs both in utero and through breastfeeding. Levels of hexachlorobenzene (HCB) in the cord serum of newborns from a population located in the vicinity of an electrochemical factory in Spain are among the highest ever reported. We aimed to assess the degree of breast milk contamination in this population and the subsequent exposure of children to these chemicals through breastfeeding. A birth cohort including 92 mother–infant pairs (84% of all births in the study area) was recruited between 1997 and 1999 in five neighboring villages. OCs were measured in cord serum, colostrum, breast milk, and children's serum at 13 months of age. Concentrations of OCs were detected and quantified in all colostrum and milk samples. The concentrations in mature milk were lower than those encountered in colostrum. At 13 months of age the highest concentration of OC was found for dichlorodiphenyl dichloroethane (p,p′-DDE), in contrast to what these children presented at birth, where HCB was the highest compound. Those infants who were breastfed had higher concentrations at the age of 1 than those who were formula fed (2.13ng/mL of HCB among formula feeders vs 4.26 among breast feeders, and 1.95 of p,p′-DDE vs 6.00 (P<0.05)). Long-term breastfeeding leads to a dose–response increase of the concentrations in children's serum during the first year of life.

Pollution by hexachlorobenzene and pentachlorophenol in the coastal plain of São Paulo state, Brazil

Organochlorine compounds were dumped by chemical industries during the 1970s in many areas of the coastal plain of São Paulo state in Brazil. These dumps, located on hillsides and in valleys, in both rural and urban environments, are responsible for soil and water pollution. The objective of this work was to determine how the pollutants have spread in an area occupied by a spodosol-type soil mantle. The study combines soil morphological observations with soil and water analysis of hexachlorobenzene (HCB) and pentachlorophenol (PCP) in soil toposequences. The results indicate that the highest pollutant concentrations are observed near the dump site and that the compounds contamination is increasing. A map integrating topography and chemical concentrations was created to visualize the spatial distribution of HCB levels in the landscape. Physical and chemical analyses were performed to measure HCB and PCP levels in the soil. Soil water appears to act as a vector of HCB, probably through complexation with and dispersal of dissolved organic matter. The persistence of HCB at the studied site is most likely due to the low pH values in combination with a high content of organic matter. HCB was consistently found in higher concentrations than PCP. It is plausible that the cause of this difference is that PCP is degraded more easily under sunlight than HCB and that degradation of PCP under acid conditions leads to the formation of HCB.

Mixed Function Oxidase Activity and Organochlorine Levels in Farmed Sharpsnout Seabream (Diplodus puntazzo) from Two Intensive Aquaculture Facilities

Mixed function oxidase (MFO) activities and organochlorine levels were investigated in liver of farmed sharpsnout seabream bred in two intensive facilities, a sea farm and a land-based farm. The aim of this study is to investigate how different facility locations and breeding conditions might affect fish metabolic capabilities and accumulation of toxic chemicals in farmed sharpsnout seabream. The differences between breeding two or more fish species in the same cage or tank known as polyculture, and monoculture (1 species) were also investigated. The results showed that both facility location (sea and land) as well as breeding systems (polyculture and monoculture) might be responsible for the differences observed in both MFO enzyme activity and organochlorine levels. Significantly higher activities of two metabolizing enzymes such as 7-ethoxyresorufin-O-deethylase (EROD) and benzo(a)pyrene monooxygenase (B(a)PMO) were in fact recorded in land-based farmed fish than in sea farmed ones, and much higher in those from polyculture than in monoculture (p < 0.05). By contrast, the highest levels of dichlorodiphenyldichloroethilene (pp′DDE) and polychlorinated biphenyls (PCBs as Aroclor 1260) were measured in sea-farmed fish, except for hexachlorobenzene (HCB), which gave higher levels in land-based farmed fishes. No significant differences were observed between monoculture and polyculture in p,p′DDE and PCBs levels except for p,p′DDE which was significantly higher in monoculture than in polyculture (p < 0.05) in fish reared in tanks. Finally significantly higher HCB levels were measured in fish reared in monoculture in tanks (p < 0.05) and in polyculture in cages (p < 0.05). The low TEQ values obtained for PCB congeners at liver level indicated no concern for fish health.

Chemical contaminants and their effects in fish and wildlife from the industrial zone of Sumgayit, Republic of Azerbaijan.

Sediment from a wetland adjacent to an industrial wastewater treatment plant in Sumgayit contained concentrations of total PAHs, total PCBs, aldrin, biphenyl, chlordane, DDT, mercury, beta-endosulfan, heptachlor, alpha-hexacyclohexane (alpha-HCH), gamma-HCH, and several individual PAH congeners that were elevated relative to published sediment quality guidelines. Chemical analyses of tissues from European pond turtles (Emys orbicularis) had increased levels of many of the same chemicals including aldrin, chlordane, heptachlor, alpha-HCH, total PCBs, total PAHs, and mercury, compared to reference turtles. In addition, turtle tissues contained elevated levels of DDD, hexachlorobenzene (HCB), and pentachlorobenzene that were not elevated in the sediment sample. Some differences were observed in contaminant levels between European pond turtles and Caspian turtles (Mauremys caspica) taken from the ponds in Sumgayit. Salmonella/microsome mutagenicity assays on pond sediments were negative or weakly positive. Micronuclei in European pond turtles were statistically correlated with tissue levels of mercury, heptachlor, DDD, HCB, and trans-nonachlor. Microcosm experiments using Russian sturgeon (Acipenser gueldenstaedtii) showed a positive dose-response relationship between exposure to suspended contaminated pond sediment and acute toxicity. Chemical and biological assays used in this study show the industrial area of Sumgayit is heavily contaminated with a complex mixture of toxic pollutants. Exposure to contaminated sediments produced acute effects in Russian sturgeon, but genotoxic effects appear to be slight.

Levels of organochlorine compounds in spotted dolphins from the Coiba archipelago, Panama

Blubber and skin samples from 63 spotted dolphins ( Stenella attenuata) (18 males, 40 females and 5 of unknown sex) were collected by biopsy techniques in the waters of the Coiba archipelago. Blubber was analyzed for organochlorine compounds and skin for gender determination. Mean levels of HCB (hexachlorobenzene), tPCB (polychlorinated biphenyls) and tDDT (dichlorodiphenyltrichloroethane) were 0.064, 2.30 and 6.4 mg kg −1, respectively. These levels are low and are not considered to represent a threat to the S. attenuata population. No significant differences either in concentrations of HCB, tPCB and tDDT or in PCB profiles were observed between males and females. The ratio tDDT/tPCB was 2.69, indicating predominantly agrarian versus industrial activities in the area. The ratio ppDDE/tDDT was 0.83, a high figure that suggests both a local reduction of DDT inputs and a high rate of DDT degradation. Significant quantitative and qualitative differences were observed between two schools, suggesting intra-population heterogeneity in organochlorine exposure possibly due to demographic segregation.

Dietary intake of hexachlorobenzene in Catalonia, Spain

To assess the dietary intake of hexachlorobenzene (HCB) by the population of Catalonia, Spain, a total-diet study was carried out. Concentrations of HCB were determined in food samples randomly acquired in seven cities of Catalonia between June and August 2000. A total of 11 food groups were included in the study. HCB levels were determined by HRGC/HRMS. Estimates of average daily food consumption were obtained from recent studies. HCB intake was estimated for five population groups: children (aged 4 to 9 years), adolescents (aged 10 to 19 years), male and female adults (aged 20 to 65 years), and seniors (aged >65 years). In general, HCB residues in foods were rather low excepting dairy products with a mean concentration of 0.869 ng/g wet weight. Total dietary intakes of HCB (microgram per kilogram body weight/day) were the following: children (0.0064), adolescents (0.0031), female adults (0.0025), male adults (0.0024) and seniors (0.0019). All these values are considerably lower than the WHO tolerable daily intake (TDI), which is 0.17 μg kg −1 day −1 for non-cancer effects and 0.16 μg kg −1 day −1 for neoplastic effects in humans.

Levels of exposure to organochlorine pesticides in open-air dump dwellers

To estimate the degree of internal exposure to organochlorine pesticides (persistent organic pollutants, POP) among inhabitants of an open-air dump. This was an observational study with simultaneous measurement and control, in which the criterion for subjects was that they dwelled in an area contaminated by POP and the effect of such contamination was the concentration of such substances into the blood. The study population consisted of 238 people living on an open-air dump in Pil es, in the municipality of Cubatão, SP, Brazil, and the control population was formed by 258 people, also resident in that municipality, in the Cota 200 district. The following pesticides were analysed: hexachlorobenzene (HCB), p-p'DDT, p-p'DDE, p-p'DDD, o-p'DDT, a HCH (hexachlorocyclohexane); b HCH; g HCH; aldrin; dieldrin; endrin; heptachlor; heptachlor-epoxy and mirex. The average blood level of HCB in Pil es was 4.66 g/l, which was 155 times higher than the average for Cota 200 (0.03 g/l). In Pil es the average blood concentration of total DDT was 3.71 g/l, which was twice the level found in Cota 200 (1.85 g/l). Total HCH presented blood concentrations that were six times greater in Pil es (0.84 g/l versus 0.13 g/l). A positive association was shown between dwelling in Pil es and the presence of POP in the blood, with much higher risks than in localities without the presence of these contaminants.

Case-control study of PCBs, other organochlorines and breast cancer in Eastern Slovakia.

This case-control study was designed to investigate association between polychlorinated biphenyls (PCBs) and risk of breast cancer in an area of high environmental exposure in the Michalovce district of eastern Slovakia. Incident breast cancer cases from the Michalovce district diagnosed between May 1997 and May 1999 were recruited through the Oncology Department of the District Hospital. A total of 15 individual PCB congeners, 2,2'-bis(4-chlorophenyl)-1,1-dichloroethylene (DDE), 2,2-bis(4-chlorophenyl)-1,1,1-trichloroethane (DDT), and hexachlorobenzene (HCB) were measured in the serum of 24 breast cancer patients and 88 population controls in 1998-1999. The median levels of total PCBs were similar in cases (2586 ng/g of lipid) and controls (2682 ng/g of lipid). Higher serum levels (highest vs. lowest tertile) of total PCBs (odds ratio (OR)=0.42, 95% CI 0.10-1.82, p-for trend=0.31), group 1 congeners (OR=0.37, 95% CI 0.10-1.43, P-for trend=0.02), group 2 congeners (OR=0.32, 95% CI 0.07-1.56, P-for trend=0.60), and group 3 congeners (OR=0.49, 95% CI 0.12-2.04, P-for trend=0.51) were inversely associated with risk of breast cancer. Higher serum levels of DDE (OR=3.04, 95% CI 0.65-14.3, P-for trend=0.10) were positively associated with risk of breast cancer, while there was no association for DDT (OR=1.19, 95% CI 0.27-5.23, P-for trend=0.68), and an inverse association for HCB (OR=0.45, 95% CI 0.06-3.19, P-for trend=0.67). While generally not statistically significant, PCB and HCB levels were inversely associated with risk of breast cancer in this highly exposed population. DDE, but not DDT, was positively associated with risk.