Biomedical subjects

Bert van Bavel

Publications and source records attributed to Bert van Bavel.

28 records · Page 2Linked to original sources

PubMed2004

Congener-specific accumulation and food chain transfer of polybrominated diphenyl ethers in two arctic food chains.

Congener-specific accumulation and prey to predator transfer of 22 polybrominated diphenyl ethers (PBDEs) were assessed in polar cod, ringed seal, polar bear, and beluga whale. Although the concentrations found were relatively low, these results show that PBDEs have reached the Arctic. PBDE congeners 47, 99, and 100 were dominant in all species studied. The pattern in ringed seal was somewhat simpler than in polar cod, with PBDE 47 accounting for more than 90% of the total PBDEs. In contrast, beluga whales, feeding on prey similar to that of ringed seals, showed higher PBDE levels and a more complex PBDE pattern than ringed seals. In contrast, polar bears contained only PBDE 47 in relatively small amounts. These differences in levels and patterns are likely due to species-specific differences in PBDE metabolism and accumulation. The metabolic index suggested that PBDEs 47 and 99 accumulate to the same magnitude as PCB 153 (PCB = polychlorinated biphenyl) in ringed seals and beluga whales. In contrast to beluga whales, ringed seals can metabolize PBDE 100 to some extent. Polar bears are seemingly capable of metabolizing virtually all PBDEs and are therefore unsuitable as indicators for PBDE contamination in the environment.

Animals↗

PubMed2004

Adipose tissue concentrations of p,p'-DDE and the risk for endometrial cancer.

OBJECTIVE: To evaluate in a case-control study possible risk of endometrial cancer associated with environmental endocrine disruptors. METHODS: We analyzed the adipose tissue concentrations of polychlorinated biphenyls, hexachlorobenzene (HCB), p,p'-dichlorodiphenyl-dichloroethylene (p,p'-DDE), chlordanes, and polybrominated biphenyls in 76 cases with endometrial cancer and 39 controls with benign endometrial hyperplasia. RESULTS: For the different chemicals, odds ratios (ORs) and 95% confidence intervals (CI) were close to unity taking the median concentration among the controls as cutoff value. However, for p,p'-DDE OR = 1.9, 95% CI = 0.8-4.8 was obtained. Additional estrogen replacement therapy yielded in this category OR = 2.3, 95% CI = 0.6-8.6. CONCLUSION: The results suggest an interaction between p,p'-DDE and estrogen replacement drugs in the etiology of endometrial cancer, although no significant associations were found.

Adipose Tissue↗

PubMed2003

Time trends of selected persistent organic pollutants in lake sediments from Greenland.

Sediments from seven lakes in West Greenland were used as natural archives to study past and present levels of PCBs (polychlorinated biphenyls, tri- to decachlorinated), tetra-BDE #47 (2,2',4,4'-bromodiphenyl ether), chlordane (cis- and trans-octachlordane) and HxCBz (hexachlorobenzene). The concentrations found are lower than or comparable to concentrations found in sediments from other Arctic regions and one to 2 orders of magnitude lower than concentrations typically found in sediments at lower latitudes. The observed temporal trends (direct and indirect dating) show a decreasing total PCB concentration. Even though local contamination sources exist, the POP deposition in the studied area is most likely a result from long-range transport. The hypothesis about "cold condensation" suggests a latitudinal fractionation to occur between different volatile compounds during the transport toward the pole. In this study a time delay in the deposition for the low-chlorinated PCBs (tri- and tetrachlorinated), compared to their emission histories and compared to higher chlorinated PCBs, was indicated. Although very low tetra-BDE #47 concentrations are observed in this study, there are indications for an increasing concentration in recent sediment layers that may reflect increasing environmental concentrations at lower latitudes. The investigated pesticides are still in use at lower latitudes, however neither chlordane nor HxCBz show any distinct temporal trend of increasing or decreasing concentration toward the sediment surface.

Chlordan↗

PubMed2003

Levels and patterns of polycyclic aromatic hydrocarbons in incineration ashes.

Polycyclic aromatic hydrocarbons were analysed in weathered bottom ash from municipal solid waste incineration, fly ash from a mixed heating plant and an ash mixture from different kinds of biofuels. Although of different origin and age, all three ashes are evaluated in different small-scale fill applications. The ultimate goal is the usage of these ashes on a larger scale. The samples were Soxhlet extracted and analysed using GC/MS in the full scan mode. The sum of the 16 US EPA PAHs was found to vary from 140 microg/kg up to more than 77000 microg/kg. Total amounts of PAHs were similar in bottom ash and in fly ash. The concentration in the mixed biofuel ash was more than 10 times higher, and exceeded the generic guidelines for PAHs in soil set by the Swedish Environmental Protection Agency. The patterns of the individual PAHs normalised to the total concentration of PAHs were found to be very similar for all the three ashes. Naphthalene and phenanthrene were the dominating PAHs for all ash samples, but the mixed biofuel ash also contained high levels of fluoranthene and pyrene.

Journal Article↗

PubMed2003

Multivariate characterization of polycyclic aromatic hydrocarbons using semi-empirical molecule orbital calculations and physical data.

Multivariate characterization of 60 polycyclic aromatic hydrocarbons (PAHs) was performed using data from literature and semi-empirical molecular orbital calculations. This dataset was analyzed by principal component analysis and projections to latent structures by means of partial least square. The PAHs were found to distribute in the chemical domain in several groups mainly governed by the number of aromatic rings and the number of five-membered rings. The multivariate model and training set was used to predict GC retention times on a non-polar column (DB-5). Using a 2(4) experimental design on the principal components of the chemical characterization model, a test set of PAHs was selected dependent on the distribution in the chemical domain of the PAHs. Such a test set is expected to improve selection of PAHs for future testing and modeling of both biological and chemical responses. Although the model of GC retention times was good, the precision was however not good enough for practical use.

Environmental Pollutants↗

PubMed2003

Polycyclic aromatic hydrocarbons in weathered bottom ash from incineration of municipal solid waste.

Polycyclic aromatic hydrocarbons (PAHs) were analysed in weathered bottom ash from different municipal solid waste incinerators. The sum of the 16 "USEPA" PAHs was found to vary from 480 to 3590 microg/kg. The amounts of carcinogenic PAHs were between 89 and 438 microg/kg ash. The maximum levels of carcinogenic PAHs exceed the Swedish generic guidelines for sensitive land use. The results showed that the amount of PAHs in fresh and weathered bottom ash are similar, indicating that the PAHs are strongly bound to the ash and only limited amounts are released to the surroundings.

Carcinogens↗

PubMed2003

Flux estimates and sedimentation of polychlorinated naphthalenes in the northern part of the Baltic Sea.

The concentrations and fluxes of polychlorinated naphthalenes (PCNs) were measured in surface sediments, and settling particulate matter collected in sediment traps, at two coastal and two offshore sampling stations in the Gulf of Bothnia, northern Baltic Sea, Sweden. The PCN concentrations (of tetra- to hepta-chloro congeners) in the surface sediments ranged from 0.27 to 2.8 ng/g dry weight and were of the same order of magnitude as background concentrations reported previously in Europe. The PCN fluxes in the southern basin (0.93 and 0.86 microg/m2/year) of the Gulf of Bothnia were higher than those in the northern basin (0.58 and 0.49 microg/m2/year); they were also higher near the coast than in the open sea. These PCN fluxes are similar to the pre-industrial levels determined from lake sediments in northwest England. The PCN homologue distribution changed from a relatively even distribution in samples collected near the coast, to TeCNs dominating in the samples from the open sea. This indicates that higher chlorinated PCNs are deposited and retained in sediments to a higher degree near the coast. The total annual deposition of PCNs in sediments in the Gulf of Bothnia was estimated to be 91 kg/year.

Geologic Sediments↗

PubMed2003

Increased concentrations of polychlorinated biphenyls, hexachlorobenzene, and chlordanes in mothers of men with testicular cancer.

An increasing incidence of testicular cancer has been reported from several countries in the Western world during the last decades. According to current hypothesis, testicular cancer is initiated during the fetal period, and exposure to endocrine disruptors, i.e., xenoestrogens, has been of concern. In this investigation we studied the concentrations of the sum of 38 polychlorinated biphenyls (PCBs), p,p'-dichlorodiphenyl-dichloroethylene, hexachlorobenzene (HCB), and chlordanes, in 61 cases with testicular cancer and 58 age-matched controls. Furthermore, case and control mothers were also asked to participate, and 44 case mothers and 45 control mothers agreed. They were of similar age. In cases only the concentration on lipid basis of cis-nonachlordane was significantly increased, whereas case mothers showed significantly increased concentrations of the sum of PCBs, HCB, trans- and cis-nonachlordane, and the sum of chlordanes. Among case mothers the sum of PCBs yielded an odds ratio (OR) of 3.8; 95% confidence interval (CI), 1.4-10 was calculated using the median concentration for the control mothers as cutoff value. For HCB, OR = 4.4 (95% CI, 1.7-12); for trans-nonachlordane, OR = 4.1 (95% CI, 1.5-11); for cis-nonachlordane, OR = 3.1 (95% CI, 1.2-7.8); and for sum of chlordanes, OR = 1.9 (95% CI, 0.7-5.0). No consistent different risk pattern was found for seminoma or nonseminoma testicular cancer.

Case-Control Studies↗

PubMed2002

Polychlorinated naphthalene levels, distribution, and biomagnification in a benthic food chain in the Baltic Sea.

The scientific literature contains little information regarding bioaccumulation and biomagnification of polychlorinated naphthalenes (PCNs) in food webs. Here we present new information on the food chain transfer of PCNs within a food chain in a subarctic environment PCNs (tetra- to hepta-chloro congeners) were measured in surface sediments and in a marine benthic food chain, comprising amphipods, isopods, and fourhorned sculpins. Samples were collected from five locations in the Gulf of Bothnia, northern Baltic Sea. PCN concentrations in the sediments were similar to background levels determined previously in sediments from the northern hemisphere. Measurement of the carbon content of the sediments allowed the calculation of biota to sediment accumulation factors (BSAFs). Tetra- and penta-CNs exhibited BSAF values greater than one, while BSAFs for the more chlorinated PCNs were less than one. This suggests more efficient assimilation, by amphipods, of the less chlorinated PCNs. A decrease in sigmaPCN concentrations from the lowest to the highest trophic level was demonstrated (amphipods: 10-69 ng/g lw, isopods: 3.9-16 ng/g lw; fourhorned sculpins: 0.54-1.5 ng/g lw). Biomagnification factors (BMFs) were calculated based on the concentrations of the congeners. These indicated that a few congeners biomagnified significantly: the highest BMFs (0.09-1.4) were found for 2,3,6,7-substituted congeners and those lacking adjacent hydrogen-substituted carbon atoms.

Amphipoda↗

PubMed2002

Development of a high-performance liquid chromatography carbon column based method for the fractionation of dioxin-like polychlorinated biphenyls.

A method to separate polychlorinated biphenyls (PCBs) by using high-performance liquid chromatography (HPLC) was developed. The HPLC column was packed with Amoco PX-21 activated carbon dispersed on octadecylsilane (ODS). The separation was carried out by gradient elution with n-hexane-dichloromethane and toluene in the forward direction followed by reversed elution with toluene. The results show that this HPLC method is useful for the separation of PCBs according to the number of substituted ortho chlorine atoms attached to the biphenyl structure. Average recoveries for a number of individual di-ortho PCBs, mono-ortho PCBs, and non-ortho PCBs in three selected elution windows were 97, 92, and 96%, respectively. Clophen A50, a herring sample, and a cod liver oil sample were fractionated on the column and the analytical results are compared with data from the literature. The method presented here is useful for quantitative separations of mono-ortho PCBs as well as non-ortho PCBs which have been assigned toxic equivalency factors by the World Health Organisation.

Carbon↗