Levels of dioxins, dibenzofurans, PCB and DDE congeners in pooled food samples collected in 1995 at supermarkets across the United States

Food, particularly dairy products, meat, and fish, has been identified as the primary immediate source of intake of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) for the general population. We previously reported PCDD/Fs in individual analyses of food samples from a number of countries, including the U.S., the former Soviet Union, and Vietnam. We also previously estimated daily intake of dioxins and related chemicals in Americans at various ages in these reports. In this paper, the levels of dioxins, dibenzofurans, dioxin toxic equivalents (TEQs), selected dioxin-like PCBs, and DDE (a persistent metabolite of DDT) were measured in 12 pooled food samples from over 90 individual specimens collected from supermarkets throughout the United States during 1995. Samples were pooled by food groups and then analyzed. Food samples were collected in Binghamton, New York; Atlanta, Georgia; Chicago, Illinois; San Diego, California; and Louisville, Kentucky. In addition to the meat, dairy, and fish samples, a vegan (all vegetable, fruit and grain, no animal product) diet, was simulated; this showed the lowest level of dioxins.     

Dioxins and furans in air and deposition: a review of levels, behaviour and processes

This paper is a comprehensive, critical review of the levels, behaviour and processes affecting polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs) in air and deposition. Aspects of sampling, analysis and quality assurance/control are discussed initially, before a review of the PCDD/F concentrations in ambient air is presented. The general trend in sigma P4-8 CDD/F (and sigma TEQ) is: remote sites < 0.5 pg/m3 (sigma TEQ < 10 fg/m3); rural sites approximately 0.5-4 pg/m3 (sigma TEQ approximately 20-50 fg/m3); and urban/industrial sites approximately 10-100 pg/m3 (sigma TEQ approximately 100-400 fg/m3). The commonly held view that a consistent mixture of PCDD/Fs in air exists is evaluated and questioned. Issues of seasonality and short-term changes in air concentrations are also critically discussed, with respect to the possibility of seasonal emission sources to air and seasonally dependent loss processes. Data on the gas-particle partitioning of PCDD/Fs in air are reviewed; the limited database to date is believed to provide evidence for an exchangeable transfer of PCDD/Fs between these two phases. The potential importance of photolytic and radical reaction degradation processes and wet/dry deposition processes in modifying the mixture of PCDD/Fs in air is discussed. Some homologue/congener specific 'weathering' of the mixture of PCDD/Fs emitted to the atmosphere clearly occurs, but in general PCDD/Fs have 'long' atmospheric residence times, rendering them subject to long-range atmospheric transport. Data are reviewed which relate the mixture of PCDD/Fs in air to that in deposition; this leads to the conclusion that different homologue groups (which are partitioned differently between the gas and particulate phase) are transferred to the earth's surface with broadly similar efficiencies.     

Dioxins, dibenzofurans, dioxin-like PCBs, and DDE in U.S. fast food, 1995

Food, especially dairy products, meat, and fish, is the primary source of environmental exposure to dioxins in the general population. Little data exists on dioxin levels in the popular and widely consumed "fast foods". Data presented in a previously published pilot study was limited to measuring only the levels of dioxins and dibenzofurans in three types of U.S. fast food. This study adds to the previous paper by presenting data, in addition to dioxins and dibenzofurans, on the closely related dioxin-like polychlorinated biphenyls (PCBs), and the persistent metabolite of DDT, 1,1-dichloro-2,2-bis (p-chlorophenyl) ethylene (DDE), in four types of popular U.S. fast food. These include McDonald's Big Mac Hamburger, Pizza Hut's Personal Pan Pizza Supreme, Kentucky Fried Chicken (KFC) three piece original recipe mixed dark and white meat luncheon package, and H?agen-Daz chocolate-chocolate chip ice cream. Dioxin plus dibenzofuran dioxin toxic equivalents (TEQ) ranged from 0.03 to 0.28 TEQ pg/g wet or whole weight for the Big Mac, from 0.03 to 0.29 for the Pizza, from 0.01 to 0.31 for the KFC, and from 0.03 to 0.49 TEQ pg/g for the ice cream. Daily TEQ consumption per kilogram body weight (kg/BW), assuming an average 65 kg adult and a 20 kg child, from one serving of each of these fast food ranged between 0.046 and 1.556 pg/kg in adults whereas in children the values were between 0.15 and 5.05 pg/kg. Total measured PCDD/Fs in the Big Mac, Personal Pan Pizza, KFC, and the H?agen-Daz ice cream varied from 0.58 to 9.31 pg/g. Measured DDE levels in the fast foods ranged from 180 to 3170 pg/g. Total mono-ortho PCB levels ranged up to 500 pg/g or 1.28 TEQ pg/g for the KFC and for di-ortho PCBs up to 740 pg/g or 0.014 TEQ pg/g for the pizza sample. Total PCB values in the four samples ranged up to 1170 pg/g or 1.29 TEQ pg/g for the chicken sample.     

Species and organ dependence of PCB contamination in fish, foxes, roe deer, and humans

According to previous experimental results, PCBs are deposited in muscle fat in animals and in humans, although they also reach the brain, the liver, and the lungs. The aim of the present study was to determine the concentrations of the so-called "indicator PCBs" (PCB nos. 28, 52, 101, 138, 153, 180), as described by the German ordinance for maximum concentrations of contaminants in foodstuffs, in muscle tissue, liver, and brain of four different species: fish, fox, roe deer, and humans, all exposed to PCBs directly in their environment. Potential target organs for the accumulation of these congeners were also to be identified. Furthermore, the organs or tissues were to be identified in which PCBs are accumulated, and unusual patterns of accumulation or breakdown of particular PCBs, for example the "dioxin-like PCBs" (coplanar PCBs) determined. For humans, the lungs were also included in these studies. Statistical comparison of PCB concentrations in samples from wild animals and humans showed that in spite of its relatively high fat concentration, brain tissue in all of the species examined (with the exception of fish) appeared to be better protected against accumulation of PCB than liver or muscle tissue. This protection may be the result of the blood-brain barrier, as witnessed by the relatively uniform concentration of PCBs throughout the various organs of fish, since the blood-brain barrier of fish is considerably less efficient than that of mammals. No peculiarities were found in regard to distribution of the coplanar PCBs over the other congeners in this study. This applies to the brain and other organs or tissues of the four species that were examined. Accumulations of PCBs and coplanar PCBs in the liver were only found in fox and roe deer. In contrast, humans were found to have accumulations of the high-chlorinated biphenyls studied here as well as PCB no. 118 in muscle tissue fat and not in the liver. Unexpectedly, low-chlorinated biphenyls were found to accumulate in the human lung. The results of this study show that the lung represents a target organ for the accumulation of potentially metabolically activated low-chlorinated biphenyls, indicating that the possible biological effects of PCBs on the lungs will need to receive more attention in the future.     

原料铜和氯元素对二噁英排放的影响及抑制技术

 对烧结原料中铜、氯元素对二噁英排放浓度的影响进行了研究。结果表明,烧结原料中铜、氯元素质量分数明显影响烟气中二噁英排放浓度。和基准试验相比,原料中铜质量分数由0.02%提高到0.04%,二噁英排放浓度(TEQ)由0.55提高到0.69 ng/m3;原料中氯质量分数由0.04%提高到0.06%,二噁英排放浓度(TEQ)由0.55提高到0.82 ng/m3。在烧结原料中添加少量的尿素可以显著降低二噁英排放浓度,尿素添加量为0.035%,在上述条件下,二噁英排放浓度均可降低65%以上。     

Estimated intake of PCDDs, PCDFs and co-planar PCBs in individuals from Madrid (Spain) eating an average diet

The estimated intake of PCDD/Fs and co-planar PCBs associated with an average diet consumed in Spain was investigated. The estimated total average intake for PCDDs and PCDFs from an average spanish diet was found to be 142 pg I-TEQ/day (2.4 pg I-TEQ/Kg b.w./day, for a 60 Kg person). PCDDs provided almost 80% of the total dioxin equivalents. This represents the upper bound estimate. If concentrations less than the LOD are taken as equal to zero, then the estimated average intake would be 81 pg I-TEQ/day which is the lower bound estimate. Data reported are in good agreement with those reported for other countries.     

Gas-particle partitioning of polychlorinated dibenzo-p-dioxins and dibenzofurans in the sintering process

The distribution of seventeen gaseous and particle-bound 2,3,7,8-substituted chlorinated PCDD/Fs in the flue gas of different windboxes of the sintering machine was analyzed.The influence of temperature change on the PCDD/Fs emission from the sintering process and the formation mechanism of PCDD/Fs were discussed.The result has shown that among the seventeen gaseous and particle-bound PCDD/Fs in the flue gas of different windboxes,furans occupied the major place.The proportion of the gaseous PCDD/Fs in most windboxes is from 40% to 60%.The change tendencies of the concentration of both the gaseous and particle-bound PCDD/Fs were similar,with a higher level at the end of the sintering bed.The PCDD/Fs concentration’s change tendency in the windbox was very consistent with the change of temperature of the flue gas in the windboxes.More than 60% PCDD/Fs of the total PCDD/Fs emission amount was emitted at the end of the sintering bed.Only this part of the waste gas accounted for 12% of the total waste gas volume.     

Investigation on the dioxin emissions from electric arc furnace in Taiwan

In this study,the formation mechanism and removal efficiency of polychlorinated dibenzo-p-dioxins, dibenzofurans(PCDD/Fs) achieved with bag filter(BF) in an electric arc furnace(EAF) in Taiwan is evaluated via intensive stack sampling and analysis.The results indicate that the PCDD/F concentration measured in the stack gas of the EAF investigated was 0.16 ng I-TEQ/m1,which was significantly lower than the PCDD/F emission limit(0.5 ng I-TEQ/m~3) set for existing EAFs in Taiwan.Due to the low operating temperature(<60℃) of the BF adopted by the EAF investigated,76%of total toxicity PCDD/Fs could be removed from the flue gas stream. In addition,the partitioning of PCDD/Fs between vapor and solid phase at different locations in EAF did not change significantly,while a reduction of solid-phase PCDD/Fs was observed at the outlet of BF.As the chlorination level of PCDD/Fs congener increases,the vapor pressure of PCDD/F congener decreases,resulting in the increase of PCDD/Fs existing in solid phase.Hence,the removal efficiencies of highly chlorinated congeners were significantly higher than that of lowly chlorinated congeners.PCDFs accounted for more than 85%of the TEQ in flue gas of the EAF investigated,among them 2,3,4,7,8-PeCDF(> 43%) was of the highest contribution.Overall,2,3,7,8-TCDD,2,3,7,8-TCDF and 2,3,4,7,8-PeCDF can serve as the unique congeners in the flue gas of the stainless steel EAF process.     

Lack of suppressive effects of mixtures containing low levels of methylmercury (MeHg), polychlorinated dibenzo-p-dioxins (PCDDS), polychlorinated dibenzofurans (PCDFS), and aroclor biphenyls (PCBS) on mixed lymphocyte reaction, phagocytic, and natural killer cell activities of rat leukocytes in vitro

Rat splenocyte mixed leukocyte reaction (MLR), splenic natural killer (NK) cell activity, and phagocytic activities of splenic, peritoneal, and peripheral blood leukocytes (PBLs) were evaluated in vitro to determine the immunotoxicity of mixtures containing low levels of methylmercury (MeHg), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and Aroclor polychlorinated biphenyls (PCBs). The mixtures were based on the concentrations of the chemicals in fish flesh. Leukocytes from male Fischer rats were exposed to MeHg (0.1-2 microg/ml), PCDD/PCDF mixtures (1-15 pg/ml) of three PCDDs (2,3,7,8-tetrachlorodibenzo-p-dioxin, 1,2,3,7,8-pentachlorodibenzo-p-dioxin, and 1,2,3,4,7,8-hexachlorodibenzo-p-dioxin) and two PCDFs (2,3,7,8-tetrachlorodibenzofuran and 1,2,3,7,8-pentachlorodibenzofuran), three Aroclor PCB (Aroclor 1242, 1254, and 1260) mixtures (0.01-0.5 microg/ml), or combinations of MeHg/PCB/PCDD/PCDF mixtures for 24 or 72 h before immunological assays. Phagocytosis and NK cell cytotoxicity were evaluated with a flow cytometer, and MLR of Fischer rat responder splenocytes cultured with mitomycin C-treated Long-Evans splenocytes by [3H]thymidine uptake. Exposure to MeHg (2 microg/ml) alone or with PCB/ PCDD/PCDF resulted in significant cytolethality in rat splenocytes, peritoneal leukocytes, and PBLs at 24 h exposure. Treatment with Aroclor PCB mixtures, PCDD/PCDF mixtures, 0.1 microg MeHg/ml (noncytolethal), or PCB/PCDD/PCDF mixtures with 0.1 microg MeHg/ml caused no suppression of splenocyte MLR response, splenic NK cell-mediated lysis of Yac-l cells, or phagocytosis of fluorescent beads by splenic, peritoneal, and peripheral blood phagocytic cells. The results indicate that in vitro exposure of rat leukocytes to low levels of MeHg, Aroclor PCB mixtures, PCDD/PCDF mixtures, or MeHg/PCB/PCDD/PCDF mixtures had no suppressive effects on the immune functions assayed, and thus produced no additive immunotoxicity. However, in order to predict the potential risk of these chemical mixtures to the human immune system, in vivo animal studies with blood (tissue) levels compatible with the levels of MeHg, PCBs, and PCDDs/PCDFs in exposed human populations should be evaluated.     

PCBs and dioxin-like compounds in plasma of adult Inuit living in Nunavik (Arctic Quebec)

Inuit people residing in the Arctic are unusually exposed to organochlorines through their traditional diet which includes large quantities of sea mammal fat. Recently, 499 Inuit adults from Nunavik (Arctic Quebec) participated in a large health survey and donated a blood sample for organochlorine and heavy metal analysis. Twenty pooled plasma samples were formed, each made of individual samples from the same age group, sex, and region of residence, to allow for dioxin-like compound determination. The mean total concentration of PCBs and dioxin-like compounds (the latter expressed in 2,3,7,8-TCDD toxic equivalents) were respectively 4.1 mg/kg lipids and 184.2 ng/kg lipids, compared to 0.13 mg/kg lipids and 26.1 ng/kg lipids for three control pooled plasma samples from Southern Quebec. Total PCBs and dioxin-like compound concentrations were strongly correlated (r = 0.98; p < 0.0001), increased with age and were greater in men than in women. Although the body burdens of PCBs and dioxin-like compounds are close to those which induced adverse health effects in laboratory animals, dietary benefits from the sea-food based diet still outweigh the hypothetical health risks.     

Elimination of polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) from human blood in the Yusho and Yu-Cheng rice oil poisonings

The pharmacokinetics of polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) in humans was studied by monitoring the blood concentrations of individuals who ingested a contaminated rice oil in Japan (yusho) in 1968 and in Taiwan (yu-cheng) in 1979. Sixteen yusho patients were followed from 1982 to 1990 and three yu-cheng individuals from 1980 to 1989. From the three yu-cheng patients, blood lipid values for the two persistent toxic congeners, 2,3,4,7,8-pentachlorodibenzofuran (PnCDF) and 1,2,3,4,7,8-hexachlorodibenzofuran (HxCDF), varied from 50 micrograms/kg at first sampling to about 1 micrograms/kg at last sampling corresponding to half-lives for elimination (t1/2) of 2-21/2 years. The blood lipid values for the same PCDF congeners in yusho patients varied from 5 micrograms/kg down to 0.1 micrograms/kg. The calculated t1/2 were more variable with median values closer to 10 years. Planar PCBs #126 and #169 were present at lower concentrations than the PCDFs. For seven of the other PCB congeners, half-lives for elimination in the yu-cheng individuals varied from 1.2 up to 4.6 yr depending on the degree of chlorination. For the yusho patients, the elimination for the PCBs was longer. These results show that clearance of the toxic PCDFs and PCBs in humans is non-linear with faster elimination at higher exposure followed by slower decreases as background levels are approached. Such a clearance pattern can best be explained by a two compartment liver and fat pharmacokinetic model.     

Dioxin-like and non-dioxin-like toxic effects of polychlorinated biphenyls (PCBs): implications for risk assessment

Polychlorinated biphenyls (PCBs) are persistent, bioaccumulative, and toxic contaminants in the environment. Individual PCB congeners exhibit different physicochemical properties and biological activities that result in different environmental distributions and toxicity profiles. The variable composition of PCB residues in environmental matrices and their different mechanisms of toxicity complicate the development of scientifically based regulations for the risk assessment. In this article various approaches for the assessment of risks of PCBs have been critically examined. Recent developments in the toxic equivalency factor (TEF) approach for the assessment of toxic effects due to dioxin-like PCBs have been examined. PCB exposure studies that describe non-dioxin-like toxic effects, particularly neurobehavioral effects and their effective doses in animals were compiled. A comparative assessment of effective doses for dioxin-like and non-dioxin-like effects by PCBs has been made to evaluate the relative significance of non-ortho-and ortho-substituted PCBs in risk assessment. Using mink as an example, relative merits and implications of using TEF and total PCB approaches for assessing the potential for toxic effects in wildlife was examined. There are several advantages and limitations associated with each method used for PCB risk assessment. Toxic effects due to coplanar PCBs occur at relatively smaller concentrations than those due to non-dioxin-like PCBs and therefore the TEF approach derives the risk assessment of PCBs, in the environment. The need for the refinement of TEF approach for more accurate assessment of risks is discussed.     

Levels of PCDD/Fs in soil samples in the vicinity of a municipal solid waste incinerator

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were determined in 24 soil samples collected near a municipal solid waste incinerator (Tarragona, Catalonia, Spain). Soil samples were obtained at various sites within 1.5 km from the stack. Total PCDD/F concentrations ranged from 0.225 to 5.80 ng TEQ/kg dry matter (d.m.) with a median value of 0.799 ng TEQ/kg and a mean value of 1.080 ng TEQ/kg. No remarkable PCDD/F contamination was found. The results were consistent and even lower than those reported in other international studies. Principal Component Analysis and hierarchical cluster analysis were used to compare these soil samples with a set of 10 additional samples collected outside the influence of the plant. Principal Component and hierarchical cluster analyses of soils in the vicinity of the incinerator provide patterns of PCDD/Fs quite similar from those obtained in soils collected far from the influence of that facility.     

Polychlorinated biphenyl (PCB) and dichlorodiphenyl dichloroethylene (DDE) exposure among Native American men from contaminated Great Lakes fish and wildlife

The New York State Department of Health is performing an investigation of Mohawk men, women, and infants who live at the Akwesasne Reserve along the St. Lawrence River in New York, Ontario, and Quebec Three large industrial facilities bordering the Akwesasne Reserve have seriously contaminated the soil and the sediments and fish of the adjacent St. Lawrence River with polychlorinated biphenyls (PCBs). The main study goals are to investigate the associations among the consumption of locally caught fish, residential exposure, body burdens of PCBs, and liver enzyme induction. Contamination with PCBs, polychlorinated dibenzofurans, polychlorinated dibenzodioxins, polyaromatic hydrocarbons, dichlorodiphenyl dichloroethylene (DDE) and other chemicals has been documented in locally caught fish, ducks, and other wildlife. The contamination of fish and wildlife is a major concern of the Mohawk people, since their tradition and culture emphasize the interdependence of man and his environment and because many residents formerly depended heavily on local fish and waterfowl for food. The focus of this research from 1986-1992 was on nursing women and infants. The major purpose of the current project is to determine if there are associations between dietary, residential, and occupational exposures to PCBs and DDE and individual body burdens in Mohawk men, specifically the husbands, partners, fathers, brothers, or other male relatives of the women in our other studies. In other fish-eating populations, adult men have tended to demonstrate higher PCB and DDE body burdens than women and children. Exposure estimates based on the reported consumption of locally caught fish and wildlife and residential histories will be correlated with the specific pattern of PCB congeners found in serum, thereby establishing a direct relationship between two potential sources of exposure and body burdens. Liver function will be examined through the caffeine breath test (CBT), a sensitive, noninvasive method of assessment of enzyme induction, one of the earliest detectable biological responses to PCBs in laboratory animals. This test appears promising as a method to detect subtle subclinical effects before the onset of overt clinical symptoms. The project is among the first to explore differences in dietary and other exposures, body burdens, and potential adverse health effects due to specific PCB congeners in men and women from the same source population.     

Ethoxyresorufin-O-deethylase (EROD) inducing potencies of planar chlorinated aromatic hydrocarbons in primary cultures of hepatocytes from different developmental stages of the chicken

In vitro induction of ethoxyresorufin O-deethylase (EROD) activity in cell cultures is an extensively validated tool for measuring overall potencies of mixtures of halogenated aromatic hydrocarbons (HAHs) in samples from the abiotic or biotic environment. For risk assessment with special attention to effects in wild birds, an assay was developed that makes use of chicken embryo hepatocytes. However, it was questioned whether compound-specific responses are consistent at the various developmental stages. The results of our present study show that there are considerable differences between early and late embryonal and post-hatching stages. The induction of EROD was measured in primary chicken hepatocyte cultures. The cells were isolated at day 14 and day 19 of embryonal development and at day 1 post hatching. Hepatocytes were exposed in vitro to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,7,8-tetrachlorodibenzofuran (TCDF), 3,3',4,4',5-pentachlorobiphenyl (PCB 126, IUPAC nomenclature) and 2,3',4,4',5-pentachlorobiphenyl (PCB 118). The respective compounds were chosen as representatives for dioxins, furans, non-ortho PCBs, and mono-ortho PCBs. These groups of chemicals have been identified as environmental contaminants with major dioxin-like effects that are mediated by a common receptor, the arylhydrocarbon (Ah) receptor. At all developmental stages, TCDF was more potent than TCDD. Relative potencies (RP = EC50TCDD/EC50HAH) decreased in the order TCDF < TCDD < PCB 126 < PCB 118. Depending on the developmental stage, TCDF was 1.2 to 3.4 times more potent than TCDD. PCB 126 was equipotent or less potent by a factor of 3 than TCDD. PCB 118 was 100 to 300 times less potent than TCDD. Both the mean effective concentration (EC50) and the maximum EROD activity (Ymax) of all compounds were lower in hepatocyte cultures from 14-day-old embryos than those from 19-day-old embryos or 1-day-old hatchlings. RPs were comparable in 19-day-old embryos and in hatchlings, but significantly different in 14-day-old embryos.     

Metabolic and functional consequences of successive no-flow and sustained low-flow ischaemia; a 31P MRS study in rat hearts

Sawmill workers in British Columbia (B.C.), Canada, have been exposed to chlorophenate fungicides which are known to be contaminated with polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Due to concern about the potential of these workers to have significant body burdens of PCDD/Fs, and the absence of measurements in these workers, a single-compartment pharmacokinetic model was developed to estimate the concentration of PCDD/Fs in the fat tissue of the sawmill workers. Data from a large cohort of B.C. sawmill workers and literature-based data on chlorophenate exposures and PCDD/F concentrations in chlorophenates were used in Monte Carlo simulations to predict a PCDD/F body burden distribution. The median concentrations of HxCDF and HpCDF predicted using the model for the B.C. sawmill worker population exceeded the range measured in unexposed populations. PeCDF and OCDF concentrations exceeded the range measured in unexposed populations at the 70th percentile of the model-predicted distribution, and PeCDD at the 90th percentile. The primary limitation of the model was the scarcity of input data about actual dermal and inhalation exposures to chlorophenates.     

Profiles of Great Lakes critical pollutants: a sentinel analysis of human blood and urine. The Great Lakes Consortium

To determine the contaminants that should be studied further in the subsequent population-based study, a profile of Great Lakes (GL) sport fish contaminant residues were studied in human blood and urine specimens from 32 sport fish consumers from three Great Lakes: Lake Michigan (n = 10), Lake Huron (n = 11), and Lake Erie (n = 11). Serum was analyzed for 8 polychlorinated dioxin congeners, 10 polychlorinated furan congeners, 4 coplanar and 32 other polychlorinated biphenyl (PCB) congeners, and 11 persistent chlorinated pesticides. Whole blood was analyzed for mercury and lead. Urine samples were analyzed for 10 nonpersistent pesticides (or their metabolites) and 5 metals. One individual was excluded from statistical analysis because of an unusual exposure to selected analytes. Overall, the sample (n = 31) consumed, on average, 49 GL sport fish meals per year for a mean of 33 years. On average, the general population in the GL basin consume 6 meals of GL sport fish per year. The mean tissue levels of most persistent, bioaccumulative compounds also found in GL sport fish ranged from less than a twofold increase to that of PCB 126, which was eight times the selected background levels found in the general population. The overall mean total toxic equivalent for dioxins, furans, and coplanar PCBs were greater than selected background levels in the general population (dioxins, 1.8 times; furans, 2.4 times; and coplanar PCBs, 9.6 times). The nonpersistent pesticides and most metals were not identified in unusual concentrations. A contaminant pattern among lake subgroups was evident. Lake Erie sport fish consumers had consistently lower contaminant concentrations than consumers of sport fish from Lake Michigan and Huron. These interlake differences are consistent with contaminant patterns seen in sport fish tissue from the respective lakes; GL sport fish consumption was the most likely explanation for observed contaminant levels among this sample. Frequent consumers of sport fish proved to be effective sentinels for identifying sport fish contaminants of concern. In the larger study to follow, serum samples will be tested for PCBs (congener specific and coplanar), DDE, dioxin, and furans.     

Multiple temporal components of optic flow responses in MST neurons

Activation of the hypothalamus-pituitary-interrenal (HPI) axis is characteristic of stress responses, which may result from a variety of environmental challenges. To investigate whether the stress response, and in particular the HPI axis, in tilapia (Oreochromis mossambicus) is compromised by short-term exposure to PCB 126, fish of both sexes were fed diets containing PCB 126 (50 microg/kg fish . day) for 5 days. In the first approach, which was performed twice, fish were acutely stressed for periods varying between 1 and 30 min at the end of the exposure period; in the second approach fish were sampled at the end of the exposure period either at rest or after 2 h of stress (confinement). After 5 days, the body weights in all experiments were significantly lower in PCB-fed fish than in control fish. There were no changes in basal plasma glucose levels, plasma ion concentrations, or branchial, renal, and intestinal Na,K-ATPase activity following PCB exposure. In the first experimental approach, in which fish experienced acute sampling stress, plasma cortisol levels reached lower levels in PCB-fed fish than in controls. This suggests an impaired ability to acutely activate interrenal steroidogenesis in PCB-treated tilapia. Adrenocorticotropic hormone (ACTH)- and cAMP-stimulated in vitro cortisol release from superfused head kidneys was lower in tissues from tilapia exposed to PCB 126 than in tissues from control animals. This effect persisted after 24 h in vitro, which, together with the high PCB 126 concentrations measured in the head kidneys of PCB-fed fish, may indicate direct toxic effects on the interrenal cells. The second experimental approach demonstrated that basal plasma cortisol and ACTH levels were not influenced by PCB treatment, but that the basal ACTH content of the rostral pars distalis (RPD) of the pituitary gland of PCB-fed fish was lower than that of control fish. After 2 h confinement, plasma cortisol levels and ACTH content of the RPD rose to similar values in both groups, whereas plasma ACTH levels were higher in confined PCB-fed fish than in confined controls. PCB-fed fish showed a lower hyperglycemic response to confinement than control fish. Confinement resulted in similarly elevated renal and intestinal Na,K-ATPase activities in both PCB-fed and control fish; branchial enzyme activities were not affected. Since PCB did not affect Na,K-ATPase activities and plasma ion concentrations, it is concluded that the effects of PCB 126 on the HPI axis in tilapia are not secondary to ionoregulatory dysfunction.     

A survey of PCB congeners in U.K. cows' milk

Samples of unpasteurised bulked milk, taken directly from ten herds of dairy cattle on rural and urban farms in the north west of England on five separate sampling occasions, were analysed for a range of PCB congeners. Sigma PCB concentrations (sum of 37 congeners) ranged from 3.4-16.4 ng/g milk fat with a mean sigma PCB concentration of 8.4 ng/g milk fat. The dominating congeners were 118, 153, 138 and 180, which contributed 15%, 20%, 17% and 9% of the sigma PCB load respectively. The chlorine pattern of the congeners which made moderate or major contributions to the sigma PCB concentration were typically substituted at both para positions (4,4'), while the PCB congeners not detected in the milk had at least one ring that was not 4-substituted. These results indicate the 4,4' substitution pattern as being the key to PCB persistence in cows. It is estimated that consumption of typical daily intakes of milk with the PCB concentrations measured in this study would contribute 11% of the average daily sigma PCB intake for individuals in the UK. This contribution would increase to 30% when exposure through the consumption of dairy products prepared from such milk (e.g. cheese, butter) is taken into account. It is estimated that the inclusion of the TEF assigned PCBs would typically increase the TEQ rating of cows' milk by approximately 40% over that attributed to PCDD/Fs alone.