Dose-dependent toxicological effects in rats following a 90-day dietary exposure to PCB-156 include retinoid disruption.

The toxicity of PCB-156 (2,3,3',4,4',5-hexachlorobiphenyl) was investigated in rats following subchronic dietary exposure. Groups of 10 male and female Sprague-Dawley rats were administered PCB-156 in the diet at 0, 0.01, 0.1, 1 or 10 ppm for 90 days. Dose-dependent increases were detected for the liver, lung and kidney weights, as well as for the liver EROD, PROD and UDPGT enzyme activities and liver uroporphyrin concentration. Dose-dependent decreases were observed in final body weight, body weight gain, and thymus weight. Apolar retinoid concentrations were decreased in the liver and lungs and increased in the kidneys. Histopathological examination of the liver, thyroid, and thymus showed mild to moderate dose-related changes. A LOAEL of 0.01 ppm was established, based on reduced apolar liver retinoid concentration. Benchmark dose-modelling corroborated the sensitivity of liver retinoid endpoints. The lower confidence limits (BMDL) for a 5% decrease in apolar liver retinoid concentrations were 0.0009 and 0.0007 ppm, respectively, in males and females, corresponding to a daily dose of 0.06 µg PCB-156 per kg body weight. Organizing dose-response data for the individual hepatic endpoints along the PCB-156 dosing scale revealed a sequence of events compatible with a causal link between depletion of apolar retinoids and the other liver biochemistry and pathology findings. Taken together, data suggest that the retinoid endpoints should be further evaluated for a causal relationship to PCB-induced liver toxicity and that retinoid system endpoints are identified and characterized to support health risk assessment in the emerging research fields of endocrine disruption and mixture toxicology.

Concentrations of bisphenol A in the composite food samples from the 2008 Canadian total diet study in Quebec City and dietary intake estimates.

A total of 154 food composite samples from the 2008 total diet study in Quebec City were analysed for bisphenol A (BPA), and BPA was detected in less than half (36%, or 55 samples) of the samples tested. High concentrations of BPA were found mostly in the composite samples containing canned foods, with the highest BPA level being observed in canned fish (106 ng g(-1)), followed by canned corn (83.7 ng g(-1)), canned soups (22.2-44.4 ng g(-1)), canned baked beans (23.5 ng g(-1)), canned peas (16.8 ng g(-1)), canned evaporated milk (15.3 ng g(-1)), and canned luncheon meats (10.5 ng g(-1)). BPA levels in baby food composite samples were low, with 2.75 ng g(-1) in canned liquid infant formula, and 0.84-2.46 ng g(-1) in jarred baby foods. BPA was also detected in some foods that are not canned or in jars, such as yeast (8.52 ng g(-1)), baking powder (0.64 ng g(-1)), some cheeses (0.68-2.24 ng g(-1)), breads and some cereals (0.40-1.73 ng g(-1)), and fast foods (1.1-10.9 ng g(-1)). Dietary intakes of BPA were low for all age-sex groups, with 0.17-0.33 µg kg(-1) body weight day(-1) for infants, 0.082-0.23 µg kg(-1) body weight day(-1) for children aged from 1 to 19 years, and 0.052-0.081 µg kg(-1) body weight day(-1) for adults, well below the established regulatory limits. BPA intakes from 19 of the 55 samples account for more than 95% of the total dietary intakes, and most of the 19 samples were either canned or in jars. Intakes of BPA from non-canned foods are low.

Environmental contaminants and human health in the Canadian Arctic.

The third Canadian Arctic Human Health Assessment conducted under the Canadian Northern Contaminants Program (NCP), in association with the circumpolar Arctic Monitoring and Assessment Programme (AMAP), addresses concerns about possible adverse health effects in individuals exposed to environmental contaminants through a diet containing country foods. The objectives here are to: 1) provide data on changes in human contaminant concentrations and exposure among Canadian Arctic peoples; 2) identify new contaminants of concern; 3) discuss possible health effects; 4) outline risk communication about contaminants in country food; and 5) identify knowledge gaps for future contaminant research and monitoring. The nutritional and cultural benefits of country foods are substantial; however, some dietary studies suggest declines in the amount of country foods being consumed. Significant declines were found for most contaminants in maternal blood over the last 10 years within all three Arctic regions studied. Inuit continue to have the highest levels of almost all persistent organic pollutants (POPs) and metals among the ethnic groups studied. A greater proportion of people in the East exceed Health Canada's guidelines for PCBs and mercury, although the proportion of mothers exceeding these guidelines has decreased since the previous assessment. Further monitoring and research are required to assess trends and health effects of emerging contaminants. Infant development studies have shown possible subtle effects of prenatal exposure to heavy metals and some POPs on immune system function and neurodevelopment. New data suggest important beneficial effects on brain development for Inuit infants from some country food nutrients. The most successful risk communication processes balance the risks and benefits of a diet of country food through input from a variety of regional experts and the community, to incorporate the many socio-cultural and economic factors to arrive at a risk management decision that will be the most beneficial in Arctic communities.

Persistent organic pollutants in fish oil supplements on the canadian market: polychlorinated dibenzo-p-dioxins, dibenzofurans, and polybrominated diphenyl ethers.

Canadians are interested in improving their diet through the consumption of fish oil food supplements, which are marketed to be rich in omega-3 fatty acids. Convenience samples of omega-3 enriched dietary supplements (n = 30) were collected in Vancouver, Canada, between 2005 and 2007. All of the omega-3 supplements were analyzed for polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and polybrominated diphenyl ethers (PBDEs) and, although every sample was found to contain detectable residues of PBDEs, only 24 samples were found to have PCDD/F concentrations above the level of detection. PCDD/F concentrations ranged from 0.05 pg TEQ/g lipid to 45.7 pg TEQ/g lipid in salmon and shark oils, respectively. Maximum PBDE concentrations similarly were observed in shark oil (113 microg/kg lipid), however, most supplements had concentrations below 5 microg/kg lipid. Average PCDD/F and PBDE intake estimates, based on consumption of maximum supplement dose following product label recommendations, were 4.32 pg TEQ/d and 25.1 ng/d lipid, respectively.

Persistent organic pollutants in fish oil supplements on the Canadian market: polychlorinated biphenyls and organochlorine insecticides.

Fish and seal oil dietary supplements, marketed to be rich in omega-3 fatty acids, are frequently consumed by Canadians. Samples of these supplements (n = 30) were collected in Vancouver, Canada, between 2005 and 2007. All oil supplements were analyzed for polychlorinated biphenyls (PCBs) and organochlorine insecticides (OCs) and each sample was found to contain detectable residues. The highest SigmaPCB and SigmaDDT (1,1,1-trichloro-di-(4-chlorophenyl)ethane) concentrations (10400 ng/g and 3310 ng/g, respectively) were found in a shark oil sample while lowest levels were found in supplements prepared using mixed fish oils (anchovy, mackerel, and sardine) (0.711 ng SigmaPCB/g and 0.189 ng SigmaDDT/g). Mean SigmaPCB concentrations in oil supplements were 34.5, 24.2, 25.1, 95.3, 12.0, 5260, 321, and 519 ng/g in unidentified fish, mixed fish containing no salmon, mixed fish with salmon, salmon, vegetable with mixed fish, shark, menhaden (n = 1), and seal (n = 1), respectively. Maximum concentrations of the other OCs were generally observed in the seal oil. The hexachlorinated PCB congeners were the dominant contributors to SigmaPCB levels, while SigmaDDT was the greatest contributor to organochlorine levels. Intake estimates were made using maximum dosages on manufacturers' labels and results varied widely due to the large difference in residue concentrations obtained. Average SigmaPCB and SigmaDDT intakes were calculated to be 736 +/- 2840 ng/d and 304 +/- 948 ng/d, respectively.

Colour morph of a probable queen angelfish Holacanthus ciliaris from Dry Tortugas, Florida.

An unusual colour morph of a probable Holacanthus ciliaris was observed in Dry Tortugas, Florida, which can possibly be explained by recessive homozygosity, however, further testing is necessary. This variation of H. ciliaris has previously only been described at St Paul's Rocks, Mid-Atlantic Ridge.

Human health implications of environmental contaminants in Arctic Canada: A review.

The objectives of this paper are to: assess the impact of exposure to current levels of environmental contaminants in the Canadian Arctic on human health; identify the data and knowledge gaps that need to be filled by future human health research and monitoring; examine how these issues have changed since our first assessment [Van Oostdam, J., Gilman, A., Dewailly, E., Usher, P., Wheatley, B., Kuhnlein, H. et al., 1999. Human health implications of environmental contaminants in Arctic Canada: a review. Sci Total Environ 230, 1-82]. The primary exposure pathway for contaminants for various organochlorines (OCs) and toxic metals is through the traditional northern diet. Exposures tend to be higher in the eastern than the western Canadian Arctic. In recent dietary surveys among five Inuit regions, mean intakes by 20- to 40-year-old adults in Baffin, Kivalliq and Inuvialuit communities exceeded the provisional tolerable daily intakes (pTDIs) for the OCs, chlordane and toxaphene. The most recent findings in NWT and Nunavut indicate that almost half of the blood samples from Inuit mothers exceeded the level of concern value of 5 microg/L for PCBs, but none exceeded the action level of 100 microg/L. For Dene/Métis and Caucasians of the Northwest Territories exposure to OCs are mostly below this level of concern. Based on the exceedances of the pTDI and of various blood guidelines, mercury and to a lesser extent lead (from the use of lead shot in hunting game) are also concerns among Arctic peoples. The developing foetus is likely to be more sensitive to the effects of OCs and metals than adults, and is the age groups of greatest risk in the Arctic. Studies of infant development in Nunavik have linked deficits in immune function, an increase in childhood respiratory infections and birth weight to prenatal exposure to OCs. Balancing the risks and benefits of a diet of country foods is very difficult. The nutritional benefits of country food and its contribution to the total diet are substantial. Country food contributes significantly more protein, iron and zinc to the diets of consumers than southern/market foods. The increase in obesity, diabetes and cardiovascular disease has been linked to a shift away from a country food diet and a less active lifestyle. These foods are an integral component of good health among Aboriginal peoples. The social, cultural, spiritual, nutritional and economic benefits of these foods must be considered in concert with the risks of exposure to environmental contaminants through their exposure. Consequently, the contamination of country food raises problems which go far beyond the usual confines of public health and cannot be resolved simply by risk-based health advisories or food substitutions alone. All decisions should involve the community and consider many aspects of socio-cultural stability to arrive at a decision that will be the most protective and least detrimental to the communities.

Direct thrombin injection into aneurysmal sac in a patient with a type II endoleak.

Endovascular grafting of abdominal aortic aneurysms provides a good alternative to open surgery, especially in high-risk patients. Endoleaks are a well-recognized complication and are typically diagnosed on CT. We describe a case in which a patient's endoleak was evaluated by MRI and successfully treated by direct thrombin injection into the site of the leak.

Effects of caffeine on human health.

Caffeine is probably the most frequently ingested pharmacologically active substance in the world. It is found in common beverages (coffee, tea, soft drinks), in products containing cocoa or chocolate, and in medications. Because of its wide consumption at different levels by most segments of the population, the public and the scientific community have expressed interest in the potential for caffeine to produce adverse effects on human health. The possibility that caffeine ingestion adversely affects human health was investigated based on reviews of (primarily) published human studies obtained through a comprehensive literature search. Based on the data reviewed, it is concluded that for the healthy adult population, moderate daily caffeine intake at a dose level up to 400 mg day(-1) (equivalent to 6 mg kg(-1) body weight day(-1) in a 65-kg person) is not associated with adverse effects such as general toxicity, cardiovascular effects, effects on bone status and calcium balance (with consumption of adequate calcium), changes in adult behaviour, increased incidence of cancer and effects on male fertility. The data also show that reproductive-aged women and children are 'at risk' subgroups who may require specific advice on moderating their caffeine intake. Based on available evidence, it is suggested that reproductive-aged women should consume

Mixture effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin and polychlorinated biphenyl congeners in rats.

Concern of the toxic effects and bioaccumulation of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and polychlorinated biphenyls in the environment continues to be a focus of research in persistent organochlorine contaminants. Groups of five adult female S.D. rats were administered by gavage 0, 2.5, 25, 250 or 1000 ng TCDD/kg body weight/day or TCDD in combination with a mixture of PCB congeners (PCBs) at 2 or 20 microg/kg b.w./day for a period of 28 days. Growth suppression, increased absolute and relative liver weights, and decreased thymic weight were observed in either the 1000 ng TCDD group alone, or the groups receiving a mixture of 1000 ng TCDD + 2 microg PCBs. The TCDD induced increases in liver and thymic weights were not altered by co-administration with PCBs, however, growth suppression appeared to be more pronounced in the group receiving 1000 ng TCDD + 2 microg PCBs than with TCDD alone. Treatment with TCDD at 250 ng and 1000 ng/kg resulted in a significant increase in hepatic microsomal methoxy resorufin-O-demethylase and ethoxy resorufin-O-deethylase activities which were antagonized by co-administration with PCBs. Similarly, effects of 250 ng TCDD on serum cholesterol and liver UDP glucuronosyl transferase activity and ascorbic acid were significantly reduced by co-administration with 20 microg PCBs. Other biochemical effects elicited by treatment with 1000 ng TCDD, but not affected by co-administration with PCBs include the following: increased serum albumin, decreased liver vitamin A, and increased kidney vitamin A and liver microsomal glutathione-S-transferase activity. While decreased hemoglobin, platelet, packed cell volume and red cell indices were observed in TCDD treated rats, no interactive effects were seen. The above results indicate that the mixture effects of PCBs and TCDD may be additive or antagonistic depending on the dose level and endpoints measured. For the purpose of predicting mixture effects, knowledge of mechanisms of action and toxicokinetics is required.

trans-Nonachlor and cis-nonachlor toxicity in Sprague-Dawley rats: comparison with technical chlordane.

cis-Nonachlor and trans-nonachlor are bioaccumulating components of the pesticide chlordane, which can be detected in various environmental biota and in humans. Existing studies have focused on the potential adverse health effects of the parent chlordane mixture. Comparable toxicity data are nonexistent for individual chlordane constituents such as trans-nonachlor, cis-nonachlor, or oxychlordane, which are among the most common chlordane-related environmental contaminants and tissue residues. In this study, rats were administered cis-nonachlor, trans-nonachlor, or technical chlordane by gavage for 28 days at doses of 0.25 to 25 mg/kg body weight. Residue analyses indicated that trans-nonachlor accumulation in adipose was greater than cis-nonachlor when rats were administered each chemical under identical conditions of dose and exposure. For all test chemicals, the major metabolite oxychlordane accumulated in adipose tissue. Adipose tissue residue levels of all test chemicals and the major metabolite were higher in female rats. The liver was a target organ in male and female rats, indicated by increased liver weight and histopathological changes consistent with microsomal enzyme induction. Hepatic changes were most pronounced in rats treated with trans-nonachlor. Elevated kidney weights and depressed organic ion transport were observed in males treated with trans-nonachlor and chlordane. Although in general, changes in target organs and clinical chemistry endpoints were similar for all 3 test chemicals, the approximate toxicity ranking from most to least toxic was trans-nonachlor > technical chlordane > cis-nonachlor.

Health risks to infants from exposure to PCBs, PCDDs and PCDFs.

Global contamination by a variety of anthropogenic persistent organic chemicals, such as dioxins and PCBs, has resulted in human exposure throughout all phases of development. Detectable concentrations of PCBs and dioxins have been found in amniotic fluid, placenta and foetal tissue samples while infants who are breast-fed can obtain blood levels greater than those of their mother's. In two separate food poisoning episodes where infants were exposed in utero to elevated levels of heat-degraded PCBs (PCBs, PCQs, PCDFs), a variety of adverse mental and physical developmental abnormalities have been observed. In additional human cohorts where exposure could be considered as environmental or background, more subtle effects, including lower birth weights, alterations in thyroid hormones and lymphocyte subpopulations and detriments in neurological development, have been consistently seen. In most instances, negative associations were made between in utero exposure to contaminants compared with lactational. Although the observed neurodevelopmental deficits have been described as subtle, there could be unknown consequences related to future intellectual functionality. Current regulatory efforts should focus on identification and control of environment and food chain contamination as in utero exposure is a direct consequence of the accumulated maternal body burdens.

Dioxins: WHO's tolerable daily intake (TDI) revisited.

In December 1990, the World Health Organization (WHO) established a tolerable daily intake (TDI) of 10 pg/kg b.w. (body weight) for TCDD, based on liver toxicity, reproductive effects and immunotoxicity in experimental animals, and making use of kinetic data in humans and experimental animals. Since then new epidemiological and toxicological data have emerged, in particular with respect to neurodevelopmental and endocrine effects of dioxin. Therefore, the European Centre for Environment and Health of the World Health Organization (WHO-ECEH) and the International Programme on Chemical Safety (IPCS) jointly organized a consultation on the "Assessment of the health risk of dioxins: re-evaluation of the TDI", May 1998, Geneva, Switzerland. The participants discussed the health risks for infants, cancer and non-cancer endpoints in humans and animals, mechanistic aspects, kinetic behaviour, modelling, exposure, and the applicability of the toxic equivalency (TEQ) concept. For the health risk assessment of dioxin-like compounds, the WHO Consultation focused on the most sensitive effects that are considered adverse (hormonal, reproductive and developmental effects) seen at low doses in animal studies (rats and monkeys). Human daily intakes corresponding with body burdens similar to those associated with adverse effects in animals could be estimated to be in the range of 14-37 pg/kg b.w./day. To arrive at a TDI expressed as TEQ, a composite uncertainty factor of 10 was recommended. By applying this uncertainty factor a TDI range of 1-4 pg TEQs/kg body weight was established. An extensive executive summary of the results of this WHO Consultation with all the underlying background documents will be published in Food Additives and Contaminants (in press).

The temporal relation of adherence and alliance to symptom change in cognitive therapy for depression.

This study attempted to replicate an earlier study (R. J. DeRubeis & M. Feeley, 1990) of the prediction of symptom change from process variables in cognitive therapy for depressed outpatients. Measures of in-session therapist behavior and therapist-patient interactions were correlated with prior and subsequent symptom change. One of the positive findings was confirmed, but the other received only marginal support. A "concrete" subset of theory-specified therapist actions, measured early in treatment, predicted subsequent change in depression. The therapeutic alliance was predicted by prior symptom change in 1 of the 2 later assessments, but only at a trend level. Several negative findings were similar to those obtained in the earlier study. Specifically, the alliance, an "abstract" subset of theory-specified therapist actions, and facilitative conditions did not predict subsequent change. Implications for causal inferences in psychotherapy process research are discussed.

Human health implications of environmental contaminants in Arctic Canada: a review.

This paper assesses the impact on human health of exposure to current levels of environmental contaminants in the Canadian Arctic, and identifies the data gaps that need to be filled by future human health research and monitoring. The concept of health in indigenous groups of the Arctic includes social, cultural, and spiritual dimensions. The harvesting, sharing and consumption of traditional foods are an integral component to good health among Aboriginal people influencing both physical health and social well-being. Traditional foods are also an economic necessity in many communities. Consequently, the contamination of country food raises problems which go far beyond the usual confines of public health and cannot be resolved by health advisories or food substitutions alone. The primary exposure pathway for the contaminants considered in this paper is through the traditional northern diet. For the Inuit, the OCs of primary concern at this time from the point of view of exposure are chlordane, toxaphene, and PCBs. Exposures are higher in the eastern than in the western region of the North. For Dene/Metis, exposure to OCs is in general below a level of concern. However, estimated intake of chlordane and toxaphene has been found to be elevated for certain groups and is a cause for concern if exposures are elevated on a regular basis. The developing foetus and breast-fed infant are likely to be more sensitive to the effects of OCs and metals than individual adults and are the age groups at greatest risk in the Arctic. Extensive sampling of human tissues in the Canadian north indicate that a significant proportion of Dene, Cree and Inuit had mean maternal hair mercury levels within the 5% risk-range proposed by the WHO for neonatal neurological damage. Based on current levels, lead does not appear to pose a health threat while cadmium is likely only a major risk factor for heavy smokers or consumers of large amounts of organ meats. Consumers of traditional foods are exposed to an approximately seven-fold higher radiation dose than non-consumers of traditional foods due predominantly to the bioaccumulation of natural radionuclides in the food chain. Risk determination for contaminants in country food involves a consideration of the type and amounts of food consumed and the sociocultural, nutritional, economic, and spiritual benefits associated with country foods. Risk management options that minimize the extent to which nutritional and sociocultural aspects of Aboriginal societies are compromised must always be considered.

Risk factors for predicting surgical salvage of sternal wound-healing complications.

A retrospective study was performed to determine whether clinical factors can predict which complicated poststernotomy wounds can be managed successfully by debridement and reclosure, and which wounds require a muscle flap for healing. Between January 1990 and December 1996, 3,435 median sternotomies were performed at Indiana University Medical Center and affiliated hospitals. A total of 91 patients (2.6%) were reoperated for sternal wound-healing complications. Seventy-six patients (83.5%) underwent debridement and rewiring, and 15 patients (16.5%) underwent primary flap coverage. Of the 76 patients who underwent initial rewiring, 45 (59%) healed and 31 (41%) required additional operative procedures. Of the 31 rewiring failures, 26 patients (84%) were healed with muscle flaps and 4 patients (13%) were managed with a second successful rewiring. The following clinical factors were correlated with operative procedure and outcome: history of smoking, chronic obstructive pulmonary disease, steroid use, previous sternotomy, age, diabetes, harvest of the left or right internal mammary artery (IMA), emergency operation, operation time, pump time, cross-clamp time, ischemic time, coronary artery bypass grafting alone versus combined with a valve replacement, positive wound cultures, positive blood cultures, elevated white blood cell count, and fever. When comparing patients with successful rewiring with those who had a failed rewiring, positive wound and blood cultures were significant risk factors (p < 0.05) on univariate analysis. Presence of a positive wound culture was significant on multivariate analysis. When comparing risk factors in patients who were rewired successfully versus all patients who had muscle flap coverage, the presence of a positive blood culture was significant on both univariate and multivariate analyses. We conclude patients most likely to fail rewiring and to require muscle flap closure are those with infected wounds, positive blood cultures, and possibly left IMA bypasses.

Zenker's diverticulum: analysis of surgical complications from diverticulectomy and cricopharyngeal myotomy.

OBJECTIVE: To identify risk factors for postoperative complications in patients undergoing diverticulectomy and cricopharyngeal (CP) myotomy for Zenker's diverticulum. STUDY DESIGN: Retrospective. MATERIALS AND METHODS: A chart review was conducted of all patients with a Zenker's diverticulum who were treated with diverticulectomy and cricopharyngeal myotomy at three tertiary care centers in central Indiana between 1988 and 1998. RESULTS: Of the 24 patients identified, 9 developed postoperative complications (2 medical and 7 surgical). Statistical analysis of multiple potential risk factors revealed that only diverticulum size greater than 10 cm2 at surgery placed the patient at increased risk for postoperative surgical complications. To our knowledge, this is the first report that has specifically addressed diverticulum size as an independent risk factor for postoperative surgical complications following diverticulectomy and CP myotomy. CONCLUSIONS: Given our findings, we recommend considering diverticulopexy rather than diverticulectomy in a patient with a Zenker's diverticulum greater than 10 cm2 in size if a cervical approach is the selected treatment.

PCB congener patterns in rats consuming diets containing Great Lakes salmon: analysis of fish, diets, and adipose tissue.

As part of a multidisciplinary toxicological investigation into Great Lakes contaminants, chinook salmon were collected from Lake Huron (LH) and Lake Ontario (LO) and incorporated (as lyophilized fillets) into standard rat diets as 20 or 100% of the protein complement (5 or 20%, w/w diet-LH5, LH20, LO5, and LO20 diets). Final PCB concentrations in the experiment ranged from 3.15 ng/g in the control diet to 1080 ng/g in the high-dose (20%) LO diet, with maximal estimated daily consumption by the rats of 82microg PCBs/kg body wt in the LO20 dietary group. Seventeen PCB congeners, PCB 85, 99, 101, 105, 110, 118, 128, 129, 132, 138, 149, 153, 170, 177, 180, 187, and 199, occurred at >/=3.0% of the total PCBs in the fish with no major site differences. Cumulatively, these 17 congeners accounted for up to 75% of the total PCBs in the fish compared to 44 and 54% in two commercial Aroclors, 1254 and 1260, respectively. PCB 77 was the major "dioxin-like" congener in the fish, followed by PCB 126 and then PCB 169. All major dietary congeners bioaccumulated in the adipose tissue of the rats with the exception of PCB congeners 101, 110, 132, and 149. The group of 17 major congeners accounted for up to 71% of the total PCBs in adipose tissue samples collected from the rats following up to 19 weeks of diet ingestion. Of the coplanar PCB congeners, PCB 77 appeared to bioaccumulate to a lesser extent compared to PCBs 126 and 169. When comparing PCBs in the rat adipose tissue to PCB congeners in Canadian breast milk, PCBs 44, 49, 74, and 137 tended to occur in higher amounts in the human samples (contributing together 18.4 vs. 1.4% of the total PCB concentration), whereas PCB 129 occurred at higher levels in the rats (3.4 vs. 0.3% of the total PCB concentration, respectively). Although adipose tissue from the rats fed diets containing Great Lakes salmon had up to two orders of magnitude higher concentrations of PCBs compared to average human values, with the exception of some lower chlorinated congeners, similar major congeners tended to be present in both the rats in the present study and humans.