Neurobehavioral deficits associated with PCB in 7-year-old children prenatally exposed to seafood neurotoxicants.

Prenatal exposure to polychlorinated biphenyls (PCBs) was examined by analysis of cord tissue from 435 children from a Faroese birth cohort. Analysis of 50 paired cord blood samples showed excellent correlation with the cord tissue concentration (r=.90). Among 17 neuropsychological outcomes determined at age 7 years, the cord PCB concentration was associated with deficits on the Boston Naming Test (without cues, two-tailed P=.09 not adjusted for mercury; with cues, P=.03), the Continuous Performance Test reaction time (P=.03), and, possibly, on long-term recall on the California Verbal Learning Test (P=.15). The association between cord PCB and cord-blood mercury (r=.42) suggested possible confounding. While no PCB effects were apparent in children with low mercury exposure, PCB-associated deficits within the highest tertile of mercury exposure indicated a possible interaction between the two neurotoxicants. PCB-associated increased thresholds were seen at two of eight frequencies on audiometry, but only on the left side, and no deficits occurred on evoked potentials or contrast sensitivity. The limited PCB-related neurotoxicity in this cohort appears to be affected by concomitant methylmercury exposure.

Pancreatic cancer and serum organochlorine levels.

Occupational exposure to p,p'-dichlorodiphenyltrichloroethane (DDT) has been associated with increased pancreatic cancer risk. We measured organochlorine levels in serum obtained at the study enrollment from 108 pancreatic cancer cases and 82 control subjects aged 32-85 years in the San Francisco Bay Area between 1996 and 1998. Cases were identified using rapid case-ascertainment methods; controls were frequency-matched to cases on age and sex via random digit dial and random sampling of Health Care Financing Administration lists. Serum organochlorine levels were adjusted for lipid content to account for variation in the lipid concentration in serum between subjects. Median concentrations of p,p'-dichlorodiphenyldichloroethylene (DDE, 1290 versus 1030 ng/g lipid; P = 0.05), polychlorinated biphenyls (PCBs; 330 versus 220 ng/g lipid; P<0.001), and transnonachlor (54 versus 28 ng/g lipid; P = 0.03) were significantly greater among cases than controls. A significant dose-response relationship was observed for total PCBs (P for trend <0.001). Subjects in the highest tertile of PCBs (> or =360 ng/g lipid) had an odds ratio (OR) of 4.2 [95% confidence interval (CI) = 1.8-9.4] compared to the lowest tertile. The OR of 2.1 for the highest level of p,p'-DDE (95% CI = 0.9-4.7) diminished (OR = 1.1; 95% CI = 0.4-2.8) when PCBs were included in the model. Because pancreatic cancer is characterized by cachexia, the impact of this on the serum organochlorine levels in cases is difficult to predict. One plausible effect of cachexia is bioconcentration of organochlorines in the diminished lipid pool, which would lead to a bias away from the null. To explore this, a sensitivity analysis was performed assuming a 10-40% bioconcentration of organochlorines in case samples. The OR associated with PCBs remained elevated under conditions of up to 25% bioconcentration.

Measurement of PCBs, DDE, and hexachlorobenzene in cord blood from infants born in towns adjacent to a PCB-contaminated waste site.

There are limited data on the concentrations of common contaminants--polychlorinated biphenyls (PCBs), dichlorodiphenyl dichloroethene (pp'-DDE) and hexachlorobenzene (HCB)--in umbilical cord blood. Cord blood provides the primary direct measure of prenatal exposure to these contaminants, the key determinant of PCBs' neurodevelopmental toxicities. The objective of this study was to characterize cord blood levels of PCBs, pp'-DDE, and HCB among 751 infants who were born between 1993 and 1998 to mothers residing adjacent to a PCB-contaminated harbor in New Bedford, Massachusetts, and for whom the neurodevelopmental toxicities of these compounds are being studied. We refined standard analytic methods to optimize the sensitivity and precision of trace-level PCB, p,p'-DDE, and HCB measurements in blood. Using these methods, we measured the concentrations of 51 individual PCBs, their sum (sum(PCB)), p,p'-DDE, and HCB in cord serum. With correction for background contamination, the respective mean+/-SD cord serum concentrations of sum(PCB), p,p'-DDE, and HCB were 0.54+/-0.83, 0.48+/-0.94, and 0.03+/-0.04 ng/g serum. These concentrations were generally lower than those in most of the few published studies with congener-specific measures of PCBs in cord blood. However, for less-chlorinated PCB congeners (e.g., congeners 99 and 118), study samples had concentrations comparable to those in other populations, including groups at risk for high dietary PCB exposure. Of note, the contaminated harbor sediment has a relatively high proportion of less-chlorinated PCB congeners. Thus, although the sum(PCB) in study infants was not higher than concentrations in infants studied elsewhere, the relative predominance of less-chlorinated congeners was generally consistent with the characteristics of the contaminated site.

Utilization of umbilical cords to assess in utero exposure to persistent pesticides and polychlorinated biphenyls.

In support of a study to relate developmental and cognitive effects with prenatal exposure to selected environmental toxicants, we developed and applied an analytical method to determine the concentration of two persistent pesticides, hexachlorobenzene (HCB) and p,p'-dichlorodiphenyldichloroethylene (DDE), and 32 specific polychlorinated biphenyl (PCB) congeners in 316 umbilical cords taken in 1986-1987 from women of the Faroe Islands. The analytical method consisted of homogenization of the cords, partitioning, microsilica gel column chromatography for clean-up, and dual-column capillary gas chromatography (DB-5 and DB-1701) with electron capture detection. Several quality control parameters were followed to monitor the performance of the method. Important criteria used before reporting unknown data were the recovery of in vitro-spiked analytes from a bovine umbilical cord (BUC) and the percentage lipid obtained for a Certified Reference Material (CRM)-350 of mackerel oil (MO). Recoveries of analytes that had been spiked at two concentration ranges (0.26-0.95 ng/g whole weight; 0.35-2.42 ng/g whole weight) into bovine cords ranged from 38.5% to 158% and from 50.4% to 145%, respectively, with a median recovery of 77.7%. Measurement of the percentage lipid for CRM-350 ranged from 73.8% to 107% with a median lipid value of 96.0%. The most prevalent analytes detected (%) in unknown umbilical cords were HCB (100), DDE (100), Ballschmiter/Zell PCBs 153 (100), 138 (98), 180 (98), 170 (93), 118 (88), 187 (86), and 146 (83), with corresponding median concentrations (ng/g whole weight) of 0.17, 1.19, 0.38, 0.30, 0.17, 0.11, 0.12, 0.09, and 0.07, respectively. Total PCB--sum of all measurable PCB congeners--had a median concentration of 1.37 ng/g whole weight. The analytes, which were very low in lipid content were also quantified on a lipid-adjusted basis, which provided an analytical challenge in these umbilical cord samples. The gravimetrically measured lipids in the human specimens ranged from 0.01% to 1.43% (median of 0.18%). In the pooled BUCs, our lipid measurements varied from 0.05% to 0.33% with a median value of 0.13%. The utility of using the umbilical cord as a matrix to assess in utero exposure to persistent environmental pollutants, compared with the use of umbilical cord blood or mother's blood, is worthy of debate.

Serum concentrations of organochlorine compounds and the subsequent development of breast cancer.

A nested case-control study was conducted to examine the association between serum concentrations of 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), the primary metabolite of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), and polychlorinated biphenyls (PCBs) and the development of breast cancer up to 20 years later. Cases (n = 346) and controls (n = 346) were selected from cohorts of women who donated blood in 1974, 1989, or both, and were matched on age, race, menopausal status, and month and year of blood donation. Analyses were stratified by cohort participation because median DDE and PCB concentrations among the controls were 59 and 147% higher in 1974 than 1989, respectively. Median concentrations of DDE were lower among cases than controls in both time periods [11.7% lower in 1974 (P = 0.06) and 8.6% lower in 1989 (P = 0.41)]. Median concentrations of PCBs were similar among cases and controls [P = 0.21 for 1974 and P = 0.37 for 1989 (Wilcoxon signed rank test)]. The risk of developing breast cancer among women with the highest concentrations of DDE was roughly half that among women with the lowest concentrations, whether based on concentrations in 1974 [odds ratio (OR), 0.50; 95% confidence interval (CI), 0.27-0.89; P(trend) = 0.02] or in 1989 (OR, 0.53; 95% CI, 0.24-1.17; P(trend) = 0.08). The associations between circulating concentrations of PCBs and breast cancer were less pronounced but still in the same direction (1974: OR, 0.68; 95% CI, 0.36-12.9; P(trend) = 0.2; and 1989: OR, 0.73; 95% CI, 0.37-1.46; P(trend) = 0.6). Adjustment for family history of breast cancer, body mass index, age at menarche or first birth, and months of lactation did not materially alter these associations. These associations remained consistent regardless of lactation history and length of the follow-up interval, with the strongest inverse association observed among women diagnosed 16-20 years after blood drawing. Results from this prospective, community-based nested case-control study are reassuring. Even after 20 years of follow-up, exposure to relatively high concentrations of DDE or PCBs showed no evidence of contributing to an increased risk of breast cancer.

Analysis of a mixture of polychlorinated biphenyls and chlorinated pesticides in human serum by column fractionation and dual-column capillary gas chromatography with electron capture detection.

An analytical method is presented for precise identification and quantitation of 29 specific polychlorinated biphenyl (PCB) congeners and 15 chlorinated pesticides in human serum. Analyte surrogates PCB 30, PCB 204, 2,2',4,4',5,5'-hexabromo-biphenyl, perthane, alpha-hexachlorocyclohexane, and dichlorobenzophenone were added to each sample. The serum was extracted with an organic solvent and separated by adsorption chromatography into 3 elution fractions for high-resolution gas chromatographic analysis. Each fraction was analyzed by dual-column capillary chromatography followed by electron capture detection. Two capillary columns, DB-5 and DB-1701, with different polarities were used to increase selectivity for each analyte. Quantitation was performed by selecting 2 sets of calibration standard mixtures and 1,2-dichloronaphthalene as an internal standard. Mean recoveries ranged from 39 to 126% for selected analytes and from 31 to 88% for surrogates. Detection limits for specific congeners and pesticides are reported. Typical chromatographic profiles of calibration standard mixtures, as well as a human sample, are illustrated. Verification of each analyte is assessed, and results of analyses of selected human samples and quality control criteria used to ensure data validity also are presented.

Profiles of Great Lakes critical pollutants: a sentinel analysis of human blood and urine. The Great Lakes Consortium.

To determine the contaminants that should be studied further in the subsequent population-based study, a profile of Great Lakes (GL) sport fish contaminant residues were studied in human blood and urine specimens from 32 sport fish consumers from three Great Lakes: Lake Michigan (n = 10), Lake Huron (n = 11), and Lake Erie (n = 11). Serum was analyzed for 8 polychlorinated dioxin congeners, 10 polychlorinated furan congeners, 4 coplanar and 32 other polychlorinated biphenyl (PCB) congeners, and 11 persistent chlorinated pesticides. Whole blood was analyzed for mercury and lead. Urine samples were analyzed for 10 nonpersistent pesticides (or their metabolites) and 5 metals. One individual was excluded from statistical analysis because of an unusual exposure to selected analytes. Overall, the sample (n = 31) consumed, on average, 49 GL sport fish meals per year for a mean of 33 years. On average, the general population in the GL basin consume 6 meals of GL sport fish per year. The mean tissue levels of most persistent, bioaccumulative compounds also found in GL sport fish ranged from less than a twofold increase to that of PCB 126, which was eight times the selected background levels found in the general population. The overall mean total toxic equivalent for dioxins, furans, and coplanar PCBs were greater than selected background levels in the general population (dioxins, 1.8 times; furans, 2.4 times; and coplanar PCBs, 9.6 times). The nonpersistent pesticides and most metals were not identified in unusual concentrations. A contaminant pattern among lake subgroups was evident. Lake Erie sport fish consumers had consistently lower contaminant concentrations than consumers of sport fish from Lake Michigan and Huron. These interlake differences are consistent with contaminant patterns seen in sport fish tissue from the respective lakes; GL sport fish consumption was the most likely explanation for observed contaminant levels among this sample. Frequent consumers of sport fish proved to be effective sentinels for identifying sport fish contaminants of concern. In the larger study to follow, serum samples will be tested for PCBs (congener specific and coplanar), DDE, dioxin, and furans.

Preliminary investigation of the use of dried-blood spots for the assessment of in utero exposure to environmental pollutants.

We determined the concentration of dichlorodiphenyldichloroethylene (p,p'-DDE) in dried-blood spot specimens from 2-day-old infants from rural Texas who had never been breast fed. Anonymous, residual whole blood spots on filter paper, previously used for routine newborn screening procedures, were soaked in a phosphate buffer, extracted with an organic solvent, and eluted through silica gel. The concentrated eluates were analyzed by capillary gas chromatography with electron capture detection (ECD). The blood collected from 10 newborns was analyzed and found to contain DDE concentrations ranging from 0.13 to 1.87 pg/microliter with a mean of 0.72 pg/microliter. One of the 10 newborns had a whole blood DDE concentration of 1.87 pg/microliter, which was greater than the concentration of 1.34 pg/microliter in a freshly drawn sample from an adult donor whose blood serum was shown to contain DDE. With improvement in detection limits, this approach has the potential to displace the analyses of mothers' blood (as a surrogate indicator of infants' exposures) and cord blood as standard procedures for determining the newborns' body burden of environmental pollutants.

An improved analysis for chlorinated pesticides and polychlorinated biphenyls (PCBs) in human and bovine sera using solid-phase extraction.

Chlorinated pesticides and polychlorinated biphenyls (PCBs) remain public health concerns because of their unresolved health impact and their persistence in humans. Current epidemiological studies of cancer, non-Hodgkins lymphoma, and endocrine disruption in National Center for Environmental Health (NCEH) laboratories require exposure assessment of many analytes in thousands of people. Previous methods of analyzing pesticides and PCBs in serum have proven inadequate for timely processing of the number of samples required for epidemiological studies. A new method that involves solid-phase extraction (SPE) and cleanup followed by dual-column gas chromatographic separation and electron capture detection has been developed. Nine surrogate compounds were added to the serum prior to sample workup to provide quality assurance for the SPE steps. These surrogates mimic the chemistry of the analytes in the extraction, cleanup, and gas chromatographic analysis steps. To increase selectivity, extracts were injected onto two gas chromatographs with different capillary columns, a DB-1701 and a DB-5. Recoveries of 17 pesticides, 28 PCB congeners, and one polybrominated biphenyl congener ranged from 40 to 80%. Recoveries from this procedure were found to be similar to those from the previously used liquid-liquid extraction method. Correlation of analyte and surrogate recoveries were compared to examine the ruggedness of the technique. The SPE method was found to provide improved sample throughput by a factor of 15.

Selected analytical methods used at the Centers for Disease Control and Prevention for measuring environmental pollutants in serum.

Blood serum is one of the more viable matrices used in assessing exposure to persistent environmental contaminants or their metabolites, especially those that are lipophilic. Analytic methods currently in use for this matrix usually involve liquid/liquid extraction followed by adsorption chromatography as a cleanup step, and low- or high-resolution gas chromatography with either electron-capture or mass spectrometric detection. The traditional analytic methods are labor intensive, have low sample throughput, and use excessive amounts of solvents and reagents. Two analytic approaches that address the requirements of modern laboratories more effectively are: 1) solid-phase extraction (SPE), used to analyze serum for several classes of compounds of environmental concern (e.g., polychlorinated biphenyls [PCBs], persistent pesticides, dioxins, furans, and coplanar polychlorinated biphenyls [CPCBs]), and 2) fast chromatography with a two-dimensional gas chromatographic system, which can be used in the determinative step for these types of analytes.

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.

Relation of a seafood diet to mercury, selenium, arsenic, and polychlorinated biphenyl and other organochlorine concentrations in human milk.

Human transition milk was sampled from 88 mothers at the Faroe Islands, where the seafood diet includes pilot whale meat and blubber. Milk mercury concentrations (median, 2.45 micrograms/liter) were significantly associated with mercury concentrations in cord blood and with the frequency of pilot whale dinners during pregnancy. Milk selenium concentrations (mean, 19.1 micrograms/liter) correlated significantly with concentrations in cord blood but not with seafood consumption. Arsenic concentrations were very low. Twenty-four of the milk samples were separated into four pools based on fish intake and milk mercury concentrations. The polychlorinated biphenyl (PCB) concentrations (1.8-3.5 micrograms/g lipid) were high and mainly due to congener numbers 153, 180, and 138. One pool contained a congener 77 concentration of 1380 ppt, which is the highest ever reported in a human specimen for a coplanar PCB. The highest PCB concentrations were seen in the pools from women who had eaten frequent whale dinners and whose milk contained high mercury concentrations. The concentrations of chlorinated dibenzo-p-dioxins and furans were not similarly elevated. Given the advantages associated with breast-feeding, advice to nursing mothers in this population should take into regard the possible risks associated with long-term exposure to milk contaminants.

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.

Environmental equity and pesticide exposure.

Although people of color and low-income groups bear a disproportionate share of the health risks from exposure to pesticides, research attention has been meager, and data on acute and chronic health effects related to their toxic exposures are generally lacking. Increased resources are needed both to study this issue and to mitigate problems already identified. People of color should be a major research focus, with priority on long-term effects, particularly cancer, neurodevelopmental and neurobehavioral effects, long-term neurological dysfunction, and reproductive outcome. Suitable populations at high risk that have not been studied include noncertified pesticide applicators and seasonal and migrant farm workers, including children.

Determination of Mirex in human blood serum containing polychlorinated biphenyls by using packed column gas chromatography.

An analytical method has been developed that uses electron capture/gas-liquid chromatography to determine Mirex in serum containing polychlorinated biphenyls (PCBs) (Aroclor 1260). With this method, 0.2 ppb Mirex can be determined in 4 mL serum that also contains 10 ppb PCBs. The method provides approximately 70% recovery of Mirex at 1.0 and 3.5 ppb. The coefficients of variation are 4.5 and 4.6% at 1.0 and 3.5 ppb, respectively. In a cooperative study with the Ohio Department of Health, the Centers for Disease Control used this method to determine the extent of exposure of Salem, OH, residents to Mirex. Confirmation of Mirex was obtained by using high resolution gas chromatography and high resolution mass spectrometry.

Evidence of an unusual pattern of polychlorinated biphenyls in the serum of some residents and canines in Paoli, Pennsylvania.

The present study uses gas liquid chromatography (GLC) electron capture detection with packed and capillary columns to detect polychlorinated biphenyls (PCBs) in serum samples from people living near the electric car repair and maintenance facility of the Southeastern Pennsylvania Transit Authority in Paoli, Pennsylvania. Most of the cohort surveyed had serum patterns similar to patterns for Aroclor 1260 (AR 1260); a small portion (3/89) had patterns indicative of an AR with higher chlorination (e.g., AR 1268). In addition to analyzing serum samples from humans, we also analyzed serum samples from canines (pets of some of the subjects). In general, the serum pattern for canines was less descriptive for AR 1260 than the pattern for humans; however, the pattern for several canines (9/16) was that of the higher chlorinated PCBs (e.g., AR 1268). By using mass spectrometry and capillary column GLC, we confirmed the presence of high molecular weight polychlorinated congeners in both human and animal samples. We were not able to show a statistically significant relationship between serum patterns of PCBs in canines and their owners or between canines and certain behavioral traits (e.g., runs free, retrieves, hours outside, hours inside). However, the correlation between PCBs quantified as AR 1268 and canines' residence time was statistically significant.

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.

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.

Determination of selected organochlorine pesticides and polychlorinated biphenyls in human serum.

A method is presented that can be used to determine the residue level of certain chlorinated pesticides and polychlorinated biphenyls (as Aroclor 1260) in serum. The method involves the following: (1) extraction of denatured serum with organic solvents; (2) elution of the organic extract through micro-Florisil columns to obtain two fractions; (3) acid treatment of the less polar Florisil fraction and its subsequent elution through deactivated silica gel to obtain two fractions; and (4) analysis of all three fractions using gas-liquid chromatography with electron capture detection. The method produced in vitro recoveries for 10 pesticides spiked in the range of 1-10.7 ppb of 50.4% to 121.6%, and in the range of 4.98-21 ppb, recoveries ranged from 47.7 to 112.6. In vivo "recoveries" of Aroclor 1260 averaged 104.8% and 92.3% for concentration levels of approximately 10 and approximately 30 ppb, respectively. The method could not be compared with the more commonly used hexane extraction technique because of the deleterious effect these extracts had on the gas chromatographic system.