Environmental contamination of ready meals by polychlorinated biphenyls (PCBs).

The level of polychlorinated biphenyls (PCBs) contamination in ready meals was investigated to determine exposure compared to other foodstuffs. Chilled ready meals from nine categories (ambient, Chinese, Indian, Traditional UK, Italian, American Tex-Mex, Vegetarian and Organic), and three samples within each category were Soxhlet extracted in triplicate with hexane for 24 h, followed by a clean-up on deactivated silica gel. The cleaned extracts were concentrated to 1 ml under N(2) gas and analyzed on gas chromatography mass spectrometry (GC-MS) for 7 target PCBs (congeners 28, 52, 101, 118, 153, 138, and 180). Individual congener concentrations ranged from non-detectable to 0.40 ng g(-1) (wet weight). The cumulative concentration of all congeners (ΣPCBs) ranged between 0.20 and 1.00 ng g(-1) (wet weight). These values translate into exposure levels of less than 1 µg kg(-1)day(-1) for reference men and women of 70 and 57 kg, respectively. This preliminary study demonstrates that ready meals, like many other foods, are contaminated by PCBs and may represent an important route of human exposure given contemporary changes in consumer food choice. Even though low levels of contamination were observed, long-term exposure for population groups consuming a high volume of ready meals may have cause for concern regarding chronic health risks.

Dissipation of naphthenic acids mixtures by lake biofilms.

The dissipation (combined sorption and biodegradation) of naphthenic acids (C(n)H(2n+z)O(2)) by lake biofilms with no previous adaptation to oil sands acids was investigated using rotating annular bioreactors. The dissipation by the biofilm was dependent on the chemical composition of the naphthenic acids mixture. There were 2 distinct groups of Fluka naphthenic acids which dissipated with pseudo first order kinetics: (a) t(1/2)= 7 days, r(2)= 0.984 and (b) components which were less readily dissipated with t(1/2)= 134 days, r(2)= 0.618. In contrast to the results observed for Fluka naphthenic acids, no dissipation was evident for lake biofilm exposed to Athabasca oil sands naphthenic acids. The differences in dissipation observed for the systems investigated are attributed to the combination of 3 key factors: (i) molecular structure and (ii) molecular mass of the naphthenic acids; along with (iii) inhibition by some components (containing elements of S and/or N acids). The later are more prevalent in oil sands naphthenic acids compared to Fluka naphthenic acids.

Polychlorinated biphenyls in bile of patients with biliary tract cancer.

BACKGROUND: Polychlorinated biphenyls (PCBs) are anthropogenic, organic compounds. Although banned in the 1970s, PCBs are poorly biodegradable and hence ubiquitous in the environment. They accumulate in adipose tissue and are implicated various malignancies, including breast and pancreatic cancer. The hepatobiliary system is the main excretory route for such xenobiotic toxins. Incidence rates of intrahepatic biliary tract cancer are increasing worldwide. Measurement and comparison of PCB levels in bile from human patients with benign and malignant bile duct disease has not previously been done. OBJECTIVES: To compare PCB concentrations in bile from patients with malignant (n=8) and non-malignant (n=7) biliary disease. METHODS AND RESULTS: Fifteen human bile samples, collected endoscopically, were analysed using gas chromatography mass spectrometry for seven target PCB congeners (28, 52, 101, 118, 153, 138, and 180), known to occur in the environment and food. Amongst males, total PCB concentrations in bile ranged from 6 ng mL(-1) (aged 73 years) to 49 ng mL(-1) (aged 90 years); and in females between 8 ng mL(-1) (aged 33 years) to 43 ng mL(-1) (aged 67 years) bile. Although there was no overall difference in mean PCB levels between non-cancer and cancer patients, levels of congener 28 were significantly higher in patients with biliary tract cancer (p<0.05). CONCLUSIONS: Despite the banning of PCBs over 30 years ago, these xenobiotics are present in the bile of patients with biliary disease. PCB levels tend to increase with age, suggesting chronic bioaccumulation. Further research is necessary to investigate the relevance of increased levels of congener 28 in bile in biliary tract cancer.

In vitro approaches to assess bioavailability and human gastrointestinal mobilization of food-borne polychlorinated biphenyls (PCBs).

This study reports on the potential for gastrointestinal (GI) mobilization and bioavailability of food-borne PCBs in humans. The development and validation of a GI simulator and operational protocols, developed in compliance with the requirements of German DIN 19738 risk assessment test procedure, are presented. Food, naturally contaminated with PCBs, was homogenized with simulated saliva fluid and shaken in the GI simulator with simulated gastric fluids (containing pepsin, mucine) for 2 h at 37 degrees C. Afterwards, the simulated intestinal fluids (containing pepsin, mucine, trypsin, pancreatin, bile) were added and the mixture shaken for a further 6 h prior to centrifugation and filtration using Buchner funnels to separate the undigested GI residues from GI fluids. PCBs were recovered from GI residues and fluids by Soxhlet and liquid-liquid extraction respectively, cleaned up using silica-SFE, and analyzed by gas chromatography mass spectrometry detection (GC-MSD). Detailed studies with fish indicate variations in mobilization and bioavailability of Sigma PCBs (28, 52, 101, 118, 153, 138 and 180). For example, the bioavailable fractions (fractions mobilized) in mackerel, salmon, crab and prawn were 0.77, 0.60, 0.54, and 0.72 respectively of the Sigma PCBs initially present in these food samples. The bioavailable fraction was dependent on the physicochemical characteristics of the PCBs. In mackerel bioavailable fractions for individual PCB congeners ranged from 0.47-0.82, from 0.30-0.70 in salmon, 0.44-0.64 in crab and in prawn from 0.47-0.77. Future studies will focus on understanding better, the variability in bioavailable fractions to be expected for different foodstuffs, in addition to tissue culture techniques using human gut cell lines to investigate a simultaneous mobilization and absorption of food-borne PCBs.

Comparison of levels of polychlorinated biphenyls in edible oils and oil-based products--possible link to environmental factors.

Food consumption has been widely reported to be the main source of human exposure to PCBs. A total of 47 samples of food products on sale in supermarkets in the United Kingdom were thus analyzed for PCBs to determine residual levels in oil and oil-based products. The objective was to compare the measured levels of total PCBs (Sigma PCBs) in food products to those reported in various environmental compartments. Combined extraction and online clean up was achieved using Accelerated Solvent Extraction (ASE) to recover target analytes for analysis by GC-MSD (gas chromatography mass spectrometry). Sigma PCBs (ng/g) in each product were in the ranges of 4.73-44.38 edible oil; 1.40-6.18 mayonnaise; 1.21-6.25 salad cream; 1.28-5.64 seafood sauce, and 0.97-15.08 exotic dressing. The level of human exposure to PCBs in all products was < 1 microg/kg body weight/day when considering a 70 kg male or 57 kg female, possibly reflecting the reported decline of PCBs in the environment.