Virlyn W. Burse

Chlorinated hydrocarbon levels in human serum: Effects of fasting and feeding

Twenty healthy adult humans had serum samples drawn on four occasions within a 24-hr period: after a 12 hr overnight fast, 4–5 hr after a high fat breakfast, at midafternoon, and the next morning after another 12 hr fast. Nonfasting samples had 22% to 29% higher mean concentrations (p < 0.05) than did fasting samples for polychlorinated biphenyls (PCBs, 4.81 vs 3.74 ng/g serum wt), hexachlorobenzene (HCB, 0.163 vs 0.134 ng/g serum wt), andp,p′-dichlorodiphenyldichloroethylene (p,p′-DDE, 6.74 vs 5.37 ng/g serum wt) measured by electron capture gas liquid chromatography. Total serum lipids were estimated from measurements of total cholesterol, free cholesterol, triglycerides, and phospholipids and were 20% higher in nonfasting samples than in fasting samples (7.05 g/L vs 5.86 g/L). When PCBs, HCB, andp,p′-DDE concentrations were corrected by total serum lipids, results from fasting and nonfasting samples were not statistically different. Because of the differences in these chlorinated hydrocarbon concentrations observed with different sample collection regimens, meaningful comparison of analytical results requires standardizing collection procedures or correcting by total serum lipid levels.

Adipose tissue/serum partitioning of chlorinated hydrocarbon pesticides in humans

Abstract As more measurements of chlorinated hydrocarbons pesticides are being performed in serum as opposed to adipose tissue, it is important to know how these compounds partition between these two compartments. We have determined concentration ratios for seven of these compounds in humans; these ratios were calculated on an adipose lipid weight vs. serum whole weight, lipid weight and albumin content.

Gas chromatographic/mass spectrometric analysis of human serum for non-ortho (coplanar) and ortho substituted polychlorinated biphenyls using isotope-dilution mass spectrometry

Abstract We have synthesized in our laboratory all of the totally carbon-13-labeled PCBs normally found in human tissues. The mixture of carbon-13-labeled PCBs consists of more than 50 congeners including the 13 c 12 -labeled, coplanar, non-ortho substituted PCBs. We used this spiking material to prepare analytical standards at various concentration levels, and established standard curves using isotope-dilution mass spectrometry for each congener over a range of concentrations normally found in human samples. The PCBs were analyzed on a Finnigan MAT 4500 in either the electron-impact or negative-ion chemical ionization mode on a DB-5 capillary column.

Determination of polychlorinated biphenyl levels in the serum of residents and in the homogenates of seafood from the New Bedford, Massachusetts, area: A comparison of exposure sources through pattern recognition techniques

We measured the residues of polychlorinated biphenyls (PCBs) in the serum of 23 residents of the New Bedford, Massachusetts, area and from two homogenates each of bluefish and lobsters from the same area. We used congener-specific and total Aroclor quantitative approaches, both of which involved gas chromatography with electron capture detection. Using gas chromatography mass spectrometry (electron ionization mode), we confirmed the presence of PCBs in the combined serum samples and in the aliquots of bluefish and lobsters. In measuring the PCB levels in serum, we found good agreement between the two electron capture detector approaches (r > or = 0.97) when the serum of specific congeners was compared to total Aroclor. We used univariate and multivariate quality control approaches to monitor these analyses. Analytical results for bluefish showed a better agreement between the two techniques than did those for lobsters; however, the small number of samples precluded any statistical comparison. We also measured levels of chlorinated pesticides in the serum samples of two groups of New Bedford residents, those with low PCB levels (< 15 ng/ml) and those with high PCB levels (> or = 15 ng/ml). We found that residents with high PCB levels also tended to have higher levels of hexachlorobenzene (HCB) and 1,1-dichloro-2,2-di-(p-chlorophenyl) ethylene (p,p-DDE). The higher concentration of all three analytes appears to be influenced by employment in the capacitor industry, by seafood consumption, or both. Using Jaccard measures of similarity and principal component analysis we compared the gas chromatographic patterns of PCBs found in the serum of New Bedford area residents with high serum PCBs with the patterns found in homogenates of lobsters (inclusive of all edible portions except the roe), in homogenates of bluefish fillets taken from local waters, and in serum from goats fed selected technical Aroclors (e.g. Aroclors 1016, 1242, 1254, or 1260). The patterns found in human serum samples were similar to the patterns found in lobster homogenates. Both of these patterns closely resembled patterns found in the serum samples of the goat fed aroclor 1254, as demonstrated by both pattern recognition techniques. In addition, the chromatographic patterns of human serum and of lobsters and bluefish homogenates all indicated the presence of PCBs more characteristic of Aroclors 1016 or 1242.

Human exposure to polychlorinated biphenyls in greater New Bedford, Massachusetts : a prevalence study

A study was conducted in the community of Greater New Bedford, Massachusetts, from 1984 through 1987 to assess the prevalence of elevated levels of polychlorinated biphenyls (PCBs) in the serum of individuals aged 18 to 64 years who had resided in the area for at least 5 years. Eight hundred and forty subjects were interviewed, examined, and tested in a cross-sectional sample of the towns of Acushnet, Dartmouth, and Fairhaven and the city of New Bedford. Serum PCBs were measured to estimate the extent of human exposure. Because of documented environmental contamination by PCBs in the New Bedford area, and the practice of recreational fishing in the harbor for food, a significant number of persons with elevated serum PCB levels were expected to be identified. Instead, the prevalence of elevated serum PCBs in the sample was found to be typical of “unexposed” urban populations in the United States. Only 1.3% of the subjects had serum PCB levels greater than 30 ppb. The same percentage was observed among males (n =391) and females (n=449). The geometric means of PCB levels were 4.3 ppb among males (Range=0.50–60.9) and 4.2 ppb among females (Range=0.38–154). We conclude that the prevalence of elevated serum PCBs is low in the population of Greater New Bedford.

Reference Range Data for Assessing Exposure To Selected Environmental Toxicants

We analyzed blood and urine specimens from 32 charter boat captains, anglers, and spouses from both groups, who reportedly ate fish from Lakes Michigan, Huron, or Erie, for selected environmental toxicants. The toxicants measured in serum were polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), coplanar polychlorinated biphenyls, other polychlorinated biphenyls (PCBs), and persistent pesticides. Nonpersistent pesticides and elements were measured in urine; and elements were measured in blood. Internal dose levels of these toxicants will be compared to reference range data that we have compiled. These reference range data will be used to ascertain the exposure status of individuals or groups within this study.

The basis for measuring 2,3,7,8-tetrachlorodibenzo-p-dioxin in serum

Abstract Because procuring blood is a much less invasive procedure than procuring adipose tissue for conducting laboratory work in epidemiologic studies, we investigated in what fraction of blood 2,3,7,8-TCDD is located, the partitioning of 2,3,7,8-TCDD between serum and adipose tissue, and the effects of fasting on the levels of selected chlorinated hydrocarbons in serum. In summary, we found that (1) 2,3,7,8-TCDD is associated almost completely with the lipoproteins in the plasma fraction, (2) its partitioning coefficient between serum and adipose tissue on a lipid basis is approximately one, and (3) when the levels are corrected for lipids, fasting has little effect on the levels of chlorinated hydrocarbons in serum.

Problems associated with interferences in the analysis of serum for polychlorinated biphenyls

During a recent survey to determine serum concentrations of polychlorinated biphenyls (PCBs) among people living around New Bedford, MA, U.S.A., an unidentified contaminant precluded the quantification of some early eluting Webb and McCall peaks. Loss of data is estimated to have reduced reported serum levels by 12%. Efforts to identify the contaminant by gas chromatography with an electron-capture detector, a Hall electrolytic condutivity detector, and mass spectrometer were not successful. Researchers ascertained, however, that the contaminant is not a PCB, it does not contain halogens, but it may contain phthalates. Vacutainer tubes and closures for serum storage bottles are suspected sources of contamination.

Selection of a Base Serum for the Preparation of Quality Control Pools Containing Environmental Analytes

Abstract At two laboratories, an analytical method to determine polychlorinated biphenyis (PCBs) in serum was evaluated for its ability to recover in vitro-spiked PCBs from bovine and human serum. Statistically significant differences (p < 0.05) were found in the results obtained for the two matrices at both laboratories. Previously an interlaboratory bias between the laboratories of + 3.3% had been established by using bovine serum; however, with human serum the average interlaboratory bias was -9.5% resulting in a change in absolute bias of approximately 13%. The analytes determined in the base materials before they were in vitro-spiked with PCBs were dichlorodiphenyldichloroethylene (p,p′-DDE), PCBs, and serum lipids (i.e., total cholesterol, triglycerides, free cholesterol and phospholipids). The concentration of analytes and lipids was higher in base human serum than in base bovine serum.

Possible approaches to establishing interlaboratory comparability of measurements of polychlorinated biphenyls in human serum

Abstract The Massachusetts Department of Public Health, with the assistance of the Centers for Disease Control, conducted a study to determine the prevalence of elevated levels (> 30 ng ml −1 ) of polychlorinated biphenyls (PCBs) in serum taken from residents of the greater New Bedford area in Massachusetts. The criteria and procedures used to establish interlaboratory comparability for measurements for PCBs in human serum, the establishment and performance of the quality control system and the comparability of results on human serum samples from the New Bedford study are described. Aspects of interlaboratory comparability addressed include the establishment of common extraction and analytical methods, joint analyses of bovine serum pools (both in vitro-spiked pools and in vivo pools from a cow that was fed PCBs), establishment of quality control charts and rules for acceptability of analytical runs and joint analyses of a subset ( n = 207) of the human serum samples from the New Bedford study. The 207 jointly analyzed samples had PCB levels that ranged from 1 to 214 ng ml −1 and had an interlaboratory correlation coefficient of 0.96.