Narayanan Kannan

Chlorobiphenyls: model compounds for metabolism in food chain organisms and their potential use as ecotoxicological stress indicators by application of the metabolic slope concept.

A model is described to explain the compositional similarities and differences in chlorobiphenyls (CBs) in members of marine food chains, including water. Four groups of CBs are distinguished based on the presence/absence of vicinal H-atoms in o,m and/or m,p vicinal H-atoms, according to structure-activity relations for their biotransformation by cytochrome P-450 1A and 2B isozymes. Contents of CBs (X) in water, diatom, mussel, copepod, worm, shrimp, flounder, herring, and harbor porpoise were transformed into molar X/153 ratios (CB-153 is persistent) and plotted against X/153 ratios in diatom, lacking metabolic efficiency. For each metabolic group, a linear plot results. Their slopes indicate relative metabolic efficiencies of cytochrome P-450 isozymes. Indication of PB-type enzyme activity in harbor porpoise, flounder, and herring that was not observed before biochemically is new. Metabolic slopes of CBs can also be used as environmental stress indicators by comparison of slopes in a selected organism in areas with different degrees of contamination.

Distribution of individual chlorobiphenyls (PCB) in solution and suspension in the Baltic Sea

Single and multidimensional GC-ECD techniques were applied to determine individual chlorobiphenyls (CBs) in solution and in suspended particles in the Baltic Sea (some data were also obtained for the adjacent German Bight in the North Sea). Large volumes (up to 1100 dm3) were analysed in transects in November 1988 and 1989 and in spring 1991. Salinity and temperature were measured continuously along the sampling tracks in all three cruises; nutrients and pH only in the latter two cruises. Concentrations of individual CBs in solution were in the sub- and low pg dm−3 range (detection limit being 0.05 pg dm−3), and of their sum between 2 and 237 pg dm−3. These concentrations are considerably lower than previously reported data. This is mainly the result of the elimination of contamination and interference problems in the sampling, clean-up and GC-ECD procedures. It may also partly reflect the reduction in the production and use of PCBs in the last decade. The highest concentrations in solution originated from local sources in the Belt Sea and the Gulf of Finland. Regional differences were found for the compositions of the CB mixtures in solution. The lowest concentrations of CBs in solution were found in areas and periods of plankton production (spring 1991), with ΣCB concentrations between 2 and 14 pg dm−3. The compositions of the CB mixtures showed regional differences in each cruise. These could be interpreted in terms of mixing between different water bodies. The classification of transects on the basis of these CB patterns agreed well with the distinction of water bodies on the basis of T-S diagrams and hydrochemical data. Concentrations of individual CBs in suspension were generally 0.1–0.5 pg dm−3, those of their sum (ΣCB) between 4 and 6 pg dm−3 during the autumn cruises. Extremely high values were found in the Belt Sea-Kattegat area in spring 1991 (up to 589 pg dm−3 for individual CBs and up to 2859 pg dm−3 for ΣCB). This probably reflects the uptake of CBs into particulates during a plankton bloom. Primary production may effectively remove CBs from the water column into the sediments. The amounts of chlorobiphenyls presently stored in the sediments of the Baltic Sea exceed the amounts in the water column by several orders of magnitude. The compositions of the CB mixtures differed considerably between solution and suspension. The relations between log K′d (apparent particle/water partition coefficient) and log Kow (octanol-water distribution coefficient) suggest the existence of (quasi-)equilibrium conditions in autumn. Deviations from this behaviour arise from biological activity in spring. The contribution of toxic congeners to the CB mixtures was dominated by the mono- and di-ortho-Cl substituted derivatives of the most toxic non-ortho-Cl CBs. The toxicity of the CB mixtures in solution was between 0.01 and 12fg dm−3 TEQs (TCDD toxic equivalents). CBs-77, -118, -105 and -156 had the largest contributions to TEQs.

A comparison between activated charcoals and multidimensional GC in the separation and determination of (non-ortho Cl substituted) toxic chlorobiphenyls

Abstract Six activated charcoals were tested, using a multidimentional GC separation technique, for their efficiencies to isolate the most toxic, non-ortho Cl substituted biphenyls (CBs) from ortho Cl CBs in order to allow their reliable determination by single column GC-ECD. The tested charcoals failed to meet the requirement of complete separation of these groups of CBs. In addition interfering non-CB compounds were found to elute from charcoals.

High resolution PCB analysis of kanechlor, phenoclor and sovol mixtures using multidimensional gas chromatography

Abstract Kanechlor-300, -400, -500 and -600, Phenoclor DP-3, -4, -5 and -6 and Sovol mixtures were analyzed for their chlorobiphenyl (CB) composition using high-resolution one-dimensional and multidimensional gas chromatography-electron capture detection (MDGC-ECD) techniques. The congener patterns of tested Kanechlor and Phenoclor mixtures resembled Aroclor 1016, 1242, 1254 and 1260. However, differences in the percentage contribution of minor constituents were noticed among these mixtures, which could be due to variations in the boiling-point fractionation of these commercial products. CB pattern of Sovol was different from the rest of the mixtures tested. It showed a composition in between ca. 30%, 40%, 50% and 60% overall chlorine levels. MDGC-ECD study showed the presence of hitherto unnoticed non-CB compounds coeluting with CBs in some commercial PCBs. The use of these mixtures as quantitation standards should be considered with caution. CB patterns of Sovol and a water extract of the Gulf of Finlan...

CB pattern in the harbour porpoise: bioaccumulation, metabolism and evidence for cytochrome P450 IIB activity.

Metabolism of chlorobiphenyls (CBs) was studied in harbour porpoise by comparing patterns of CB-X/CB-153 ratios in blood, brain, liver and blubber with the patterns in herring, the main food source. The CBs were classified in five groups, based on the presence/absence of vicinal H-atoms (vic. Hs) in meta,para (m,p) and/or ortho,meta (o,m) positions and the number of ortho-Cl-atoms (ortho-Cls). Plots of CB-X/CB-153 ratios in porpoise tissue vs the ratios in herring appeared to be linear for each CB group in all tissues. Slopes of these plots (metabolic slopes) were used as quantitative indicators of metabolic activity. In this way, activity of PB-type isozymes of the P450 monooxygenase system was apparent: in contrast to existing literature data, harbour porpoise appears to be able to metabolize congeners with m,p vic. Hs, even in the presence of more than 2 ortho-Cls. The presence of 3-MC-type (MC-type) isozymes was also detected. The metabolic slopes were also used as basis for risk assessment. Due to their metabolism the most toxic non-ortho CBs were not present in the tissues at detectable levels. We suggest a risk assessment approach which takes this into account. It is considered to be an alternative and more reliable basis for risk assessment than the use of toxic equivalent factors. The results support the model of equilibrium distribution of CBs in harbour porpoise and the role of blood as central transport medium. The model has been developed for persistent compounds; it appears to hold for metabolizable CB congeners as well.

Toxic Chlorobiphenyls in Adipose Tissue and Whole Blood of an Occupationally/Accidentally Exposed Man and the General Population

Individual polychlorinated biphenyl (CB) congeners in adipose and whole blood tissues of a capacitor manufacture worker (occupational/accidental exposure) and of the general population were determined. Nondestructive sample cleanup and multidimensional gas chromatography-electron capture detection (MDGC-ECD) techniques were applied. Special attention was given to the toxicologically relevant congeners CB-77, CB-126, CB-169, CB-105, CB-114, CB-118, CB-156, CB-167, and CB-189 (IUPAC). Lipid-based tissue contents of sigma CBs were higher in the occupationally/accidentally exposed worker (adipose = 7,000 ng/g; whole blood = 11 ng/g) than in the general population (adipose = 300 ng/g; whole blood = 1.9 ng/g). Among the non-ortho Cl CBs, CB-77 was below detection limit (< 1.0 pg/g). The contents of CB-126 for the capacitor manufacture worker were 2,000 and 3 pg/g, and in the general population were 100 and 2 pg/g for adipose and whole blood, respectively. The corresponding data for CB-169 were 3,500 and 4 for adipose and whole blood, respectively, in the exposed worker, and 40 and 2 for adipose and whole blood, respectively, in the general population. Congeners with highest contents were CB-153, CB-138, CB-180, CB-170, and CB-187. These congeners possess chlorine substitution patterns, making them resistant to metabolism. X/153 ratios suggest that both PB and 3-MC type cytochrome P-450 enzymes were induced in the exposed worker, as well as in the general population.

Structure-dependent separation method for non-Ortho PCBs with matrix-integrated quality control: A multidimensional analytical approach

A PYE 2-(1-pyrenyl)ethyldimethylsilylated silica gel] column HPLC in combination with MDGC-ECD has been developed for a sensitive and selective determination of toxic mono- and non-ortho PCBs in environmental samples. This technique was applied to environmental samples such as coastal water, suspended particulate material (SPM), coastal sediment, mussels, fish, bird and marine mammal. Determination of PCB 156 along with non-ortho congeners acted as matrix-integrated quality control parameter. This hyphenated technique offers one of the most sensitive way of determining non-ortho PCBs but also reveals the immense complexity of the coelution problem which unnoticed results in over estimation of toxic PCBs in the environmental samples.

Polychlorinated Biphenyls (Pcbs) Pollution in Sea of Japan

Deep waters of the Sea of Japan and surface waters of the Pacific Coast of Honshu and the northeast Sea of Japan were analysed for polychlorinated biphenyls (PCBs) pollution. the ΣPCB concentrations in solution in the Sea of Japan (50–3000 m) were between 140 and 1230 fg dm−3. the space-integrated surface water concentration near the Pacific coast of northern Honshu was 140 fg dm−3and for the surface water of the Sea of Japan was 230 fg dm−3. Based on these analyses four water masses were deduced in the Sea of Japan during the summer months. It is shown for the first time in the Sea of Japan that polychlorinated biphenyls are excellent chemical indicators of not only the anthropogenic pollution, but also water masses.