Biomedical subjects

Andreas Sjödin

Publications and source records attributed to Andreas Sjödin.

7 recordsLinked to original sources

PubMed2003

New high-resolution mass spectrometric approach for the measurement of polychlorinated biphenyls and organochlorine pesticides in human serum.

To increase our analytical throughput for measuring polychlorinated biphenyls (PCBs) and organochlorine (OC) pesticides without sacrificing data quality, we have developed and validated a combined PCB/OC pesticide gas chromatography-high-resolution mass spectrometry (GC-HRMS) analysis. In a single GC-HRMS analysis, both selected PCBs and OC pesticides are detected and quantified. Previously, this has been difficult, if not impossible, because of the major difference in masses of the most abundant electron-impact ions. However, we have identified slightly less abundant ions to monitor that allow us to successfully combine these analytes into a single analysis without sacrificing any analytical sensitivity or instrument reliability. Consequently, we have been able to double our analytical throughput by modification of mass spectrometric parameters alone. Our new methodology has been validated against our current GC-HRMS method, which entails using two separate injections, one for PCB analysis and one for OC pesticide analysis. The two methods differ by less than 4% overall, with no systematic bias. We used this method to analyze approximately 350 serum samples over a period of several months. We found that our new method was as reliable in automated, overnight runs as our current method.

Gas Chromatography-Mass Spectrometry↗

PubMed2003

Accumulation of airborne hexachlorocyclohexanes and DDT in pine needles.

The accumulation of alpha- and gamma-hexachlorocyclohexanes (HCHs) and p,p'-DDT in Scots pine needles was measured simultaneously with the concentrations in the surrounding air. All three compounds accumulate during the entire life span of the needles. For p,p'-DDT the general accumulation is overlaid by a concentration peak during winter, probably related to particle deposition. For the HCHs the accumulation is overlaid by a seasonal pattern with rapid accumulation during spring and summer months and constant concentrations during winter months. The concentrations of alpha-HCH in the air were more or less constant during the whole sampling period, whereas gamma-HCH shows an air concentration peak in spring and early summer. Air concentrations of p,p'-DDT were for the most part below the detection limit. There is little evidence of revolatilization from the needles, with the exception of a small decline of gamma-HCH concentration in summer after the peak air concentrations. The high accumulation rate of the HCHs during the warm season correlates with high levels of volatile organic compounds (VOCs) in the needles. We suggest that the variation of VOC content in the needles cause seasonal variation of the air-plant partitioning coefficient. An additional complicating factor is that the dry weight of the needles has to be corrected for the yearly variation of starch content. The results presented here question models of uptake of airborne contaminants by plants that assume rapid equilibria between the air and plants.

Air↗

PubMed2003

Comprehensive solid-phase extraction method for persistent organic pollutants. Validation and application to the analysis of persistent chlorinated pesticides.

The Centers for Disease Control and Prevention (CDC) is involved in many epidemiological studies regarding the measurement of chlorinated pesticides and polychlorinated biphenyls in specimens obtained from humans. In addition to these commonly determined analytes, there is a need to include additional persistent organic pollutants (POPs) in our analyses, which further stresses the analyses because sample volumes remain small. Thus, a single method of analysis for all POPs in human serum is needed. CDC has recently developed a semiautomated and comprehensive solid-phase extraction method for POPs. The method is comprehensive since it was optimized for the extraction of many different POP compound classes. We then developed a purification and fractionation scheme that allows (a) separation of different compound classes by particular functionalities and (b) purification of those fractions to remove coextracted interferences. This paper describes the first step in the semiautomated comprehensive extraction and multiple fractionation method developed by CDC for monitoring POPs. In this paper, we validate the analysis of the persistent chlorinated pesticides, a compound class difficult to examine because of their structural diversity, in human plasma. The method was validated against an existing CDC method by using a spiked quality-control serum pool. The concentrations determined for all analytes using both methods were within 2%-14% relative standard deviations. A multilevel (i.e., 3-4 point) matrix spike showed good linearity for the analytes tested (r2 = 0.978-0.999). The method was then applied to 40-year-old archived plasma samples for the quantitative analysis of selected chlorinated pesticides. Mean recoveries of the 13C-labeled internal quantification standards ranged from 64% to 123% for the 11 monitored pesticides. The overall method proved to be robust by handling old coagulated plasma samples. It allowed faster throughput of samples than our previous methods and provided cleaner samples with less frequent interferences or background as analyzed by high-resolution mass spectrometry. The method represents a preliminary step in establishing an automated, comprehensive multiresidue analysis method for POPs in human serum.

Automation↗

PubMed2003

A review on human exposure to brominated flame retardants--particularly polybrominated diphenyl ethers.

Brominated flame retardants (BFRs) have been and are still heavily used as additive or reactive chemicals in polymers and textiles. Only a few of the BFRs have been assessed in human subjects with a major data set on internal exposures to polybrominated diphenyl ethers (PBDEs). Increasing PBDE levels have been observed in mothers' milk from Sweden as well as in blood from Germany and Norway. The levels are in general lower than PCB levels. However, the PBDE concentrations found in the North Americans are considerably higher compared to European subjects. The PBDEs are dominated by 2,2',4,4'-tetrabromodiphenyl ether (BDE-47). Decabromodiphenyl ether (BDE-209) is reported both in the general population and in occupationally exposed persons showing the bioavailability of this high molecular weight compound. While the lower and medium brominated diphenyl ethers are persistent, BDE-209 has a fairly short half-life of approximately 2 weeks. Tetrabromobisphenol A (TBBPA) is readily eliminated in humans showing a half-life of about 2 days. Still, TBBPA is accumulated in humans but a continuous exposure to this BFR is required to maintain a certain level in the human subject. TBBPA has not been detected in the general population but in people exposed at work. The current review addresses human exposure routes and levels of BFRs.

Environmental Exposure↗

PubMed2003

An overview of commercially used brominated flame retardants, their applications, their use patterns in different countries/regions and possible modes of release.

Brominated flame retardants (BFRs) are used in a variety of consumer products and several of those are produced in large quantities. These compounds have been detected in environmental samples, which can be attributed to the anthropogenic uses of these compounds. Brominated flame retardants are produced via direct bromination of organic molecules or via addition of bromine to alkenes; hence, an overview of the production and usage of bromine over the past three decades is covered. Production, application, and environmental occurrence of high production brominated flame retardants including Tetrabromobisphenol A, polybrominated biphenyls, Penta-, Octa-, Deca-brominated diphenyl ether (oxide) formulation and hexabromocyclododecane are discussed.

Bromine↗

PubMed2002

Exposure to polybrominated diphenyl ethers and tetrabromobisphenol A among computer technicians.

This study investigates exposure to polybrominated diphenyl ethers (PBDEs) and tetrabromobisphenol A (TBBPA), which are used as flame retardants in electronic equipment, in a group of technicians with intense computer work. Thirteen PBDE congeners and TBBPA were quantified in serum from 19 computer technicians. Previously investigated groups of hospital cleaners with no computer experience, and clerks working full-time at computer screens were used for comparison. The computer technicians had serum concentrations of BDE-153, BDE-183 and BDE-209 that were five times higher than those reported among hospital cleaners and computer clerks. The median levels observed among the computer technicians were 4.1, 1.3, and 1.6 pmol/g lipid weight, respectively. In contrast, for BDE-47 there was no difference between the computer technicians and the others. BDE-100, BDE-203, and three structurally unidentified octa-BDEs and three nona-BDEs, were present in almost all samples from the computer technicians. Further, TBBPA was detected in 8 out of 10 samples. The levels of BDE-153, BDE-183, and one of the octa-BDEs were positively correlated with duration of computer work among technicians. On a group level an exposure gradient was observed, from the least exposed cleaners to the clerks, and to the highest exposed group of computer technicians. A dose (duration of computer work)-response relationship among computer technicians was demonstrated for some higher brominated PBDE congeners. Thus, it is evident that PBDEs used in computers and electronics, including the fully brominated BDE-209, contaminate the work environment and accumulate in the workers tissues.

Adult↗

PubMed2002

Tissue distribution and half-lives of individual polychlorinated biphenyls and serum levels of 4-hydroxy-2,3,3',4',5-pentachlorobiphenyl in the rat.

This study was done to generate kinetic data on individual congeners of chlorinated biphenyls in the low dose range, which could be of value in the risk assessment procedure. Male Sprague-Dawley rats were given a single oral dose of a mixture of polychlorinated biphenyls (CBs) containing either CBs 105, 118, 138, 153, 156, 157, 170, and 180 (A-mix) or CBs 28, 52, 77, 87, and 101 (B-mix). Liver, serum, and adipose tissue were collected after 6 h up to 135 days, from rats given the A-mix, and after 6 h up to 4 days from rats given the B-mix. CB concentrations were measured in liver, serum, and adipose tissue. In addition, this study provides kinetic data of one of the major CB metabolites, 4-hydroxy-2,3,3',4',5-pentachlorobiphenyl (4-OH-CB107). The low doses used resulted in serum CB concentrations similar to human background serum concentrations. In the A-mix experiment all CBs show high initial liver and serum concentrations followed by redistribution into adipose tissue. Differences between congeners were correlated to molecular weight. High molecular weight correlated to lower uptake and slower redistribution. During dynamic steady-state the tissue concentrations decreased with a calculated first order rate between 54-129 days for halving the concentrations (half-life). Most of the decrease in concentration was explained by the growth-related increase of tissue masses in general and adipose tissue in particular. In the B-mix experiment, the concentrations of CBs in adipose tissue decreased with between 25 and 59% from day 1 to day 4. These results show that the B-mix congeners, given at low dose, have longer half-lives than previously reported in high dose studies. Partition coefficients between body compartments are reported and for the first time a high and congener specific liver-to-serum ratio of CB 77 is observed.

Adipose Tissue↗