Concentration of organochlorine pesticides in wine corks.

Wine corks were extracted and analyzed for 23 organochlorine pesticides, including alpha-, beta-, and gamma-hexachlorocyclohexanes (HCH), hexachlorobenzene, DDT, DDE and DDD, chlordane, endosulfan, dieldrin, aldrin, and endrin. This was done to investigate the occurrence, concentrations, composition profiles, and possible sources of organochlorine contamination. All groups of compounds were detected in every sample investigated, with the exception of aldrin and endrin. The total concentrations of organochlorine compounds in all samples ranged from 75-120 ng/g lipid, and for most compounds, the concentrations of organochlorines in cork were consistent with published data for other plant tissues. Differences in the relative abundances of the various classes of organochlorine pesticides were substantial and were probably due to differences in the pesticide usage practices of the various regions in which the cork producing trees were grown.

A comparison of PAH, PCB, and pesticide concentrations in air at two rural sites on Lake Superior.

Atmospheric concentrations of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and pesticides were compared at Brule River and Eagle Harbor, two rural sites on Lake Superior that are part of the Integrated Atmospheric Deposition Network (IADN). Brule River lies 40 km southwest of Duluth, MN, a small industrial city, and Eagle Harbor is in Michigan's upper peninsula, 400 km east of Brule River. Pesticide and PCB concentrations were similar at both sites. Day-by-day regression analyses of the data showed that PAH concentrations, an indication of urban contamination, were significantly higher at Brule Riverthan at Eagle Harbor. Concentration ranges for all compounds at both sites were well within global background levels, despite the differences observed between the two sites. Clearly, pollution from Duluth is influencing PAH concentrations at Brule River more than at Eagle Harbor.

Understanding enantioselective processes: a laboratory rat model for alpha-hexachlorocyclohexane accumulation.

Since cyclodextrin gas chromatography columns became popular for chiral separations, many researchers have noticed high enantiomeric ratios [ER: (+)-enantiomer/(-)-enantiomer] for alpha-HCH in the brains of wildlife. This investigation used the laboratory rat as a model for these phenomena. Rats were either pretreated with phenobarbital (PB) or left untreated and then dosed with alpha-HCH. Animals were sacrificed after 1 or 24 h. The ER averaged 0.95 +/- 0.01 in blood, 1.29 +/- 0.02 in fat, and 0.77 +/- 0.004 in liver. ERs in brain ranged from 2.8 +/- 0.5 to 13.5 +/- 0.4. Both the tissue concentration distribution and the ERs agree well with those previously reported in wildlife. To determine whether high brain ERs were due to enantioselective metabolism or transport through the blood-brain barrier, alpha-HCH exposed brain and liver tissue slices were compared. Concentrations in the brain slices did not decrease with PB pretreatment but did decrease in the liver slices. Enantiomeric ratios in the brain slices averaged 1.11 +/- 0.02 and were 0.76 +/- 0.03 in liver slices for the PB pretreated rats. These data indicate that the enantioselective metabolism of alpha-HCH by the brain is not the mechanism responsible for high ERs in this tissue.

Concentrations and spatial variations of polybrominated diphenyl ethers and other organohalogen compounds in Great Lakes air.

Air samples were analyzed from urban, rural, and remote sites near the Great Lakes to investigate the occurrence, concentrations, and spatial and temporal differences of polybrominated diphenyl ethers (PBDE) in air. The concentrations of PBDEs were compared to those of other organohalogen compounds such as PCBs and organochlorine pesticides. The samples were collected in 1997-1999 as part of the Integrated Atmospheric Deposition Network (IADN). To minimize the variability of the data, we selected only samples taken when the atmospheric temperature was 20 +/- 3 degrees C. PBDEs were found in all samples, indicating that these compounds are widely distributed and that they can be transported through the atmosphere to remote areas. The total concentrations of PBDEs were similar to some of the organochlorine pesticides such as sigmaDDT and ranged from 5 pg/m3 near Lake Superior to about 52 pg/m3 in Chicago. In fact, the spatial trend was well correlated to those of PCBs. Our results indicate a relatively constant level from mid-1997 to mid-1999. At 20 +/- 3 degrees C, about 80% of the tetrabromo homologues are in the gas phase and about 70% of the hexabromo homologues are associated with the particle phase. Thus, particle-to-gas partitioning in the atmosphere is an important process for these compounds.

Methylene retention indexes for isolated toxaphene congeners.

Toxaphene was a heavily used, broad-spectrum insecticide, which was banned in most countries in the 1980s. Early data suggested that a limited number of congeners in the technical mixture were responsible for its toxicity to insects. However, toxaphene research has historically focused on analyzing total toxaphene, largely due to insufficient analytical methodology to measure the individual congeners. In recent years, congener-specific toxaphene research has flourished due to analytical advances leading to the identification of several congeners, about 25 of which are commercially available. However, the high price of these standards may inhibit toxaphene research in some laboratories. We report here the methylene retention indexes for 28 isolated toxaphene congeners. When used in conjunction with mass spectrometry, methylene retention indexes provide an alternative method for identifying these compounds when direct comparison with standard compounds is not practical.

Volatilization of toxaphene from Lakes Michigan and Superior.

The pesticide toxaphene was used extensively on cotton in the southern United States until its use was restricted in 1982. It was previously reported that the upper Great Lakes have received toxaphene by gas absorption following long-range transport from the south and are currently saturated with respect to toxaphene. However, the rate of loss of toxaphene from Lakes Michigan and Superior had been estimated using sparse or estimated data, and thus, these estimates had high uncertainties. For this investigation, samples were collected to provide extensive data on air, water, and sediment concentrations of toxaphene for the upper Great Lakes for the period 1997-98. These data were used to calculate the annual and seasonal fluxes of toxaphene from water to air and sediment. Lake Superior is 200-1000% saturated with toxaphene, and Lake Michigan is 200-500% saturated. It seems clear that both lakes will outgas toxaphene into the atmosphere for some considerable time in the future, and Lake Superior, because of its generally lower water temperatures and higher toxaphene concentration, will outgas toxaphene even longer than will Lake Michigan.

Environmentally relevant xenoestrogen tissue concentrations correlated to biological responses in mice.

The effects of xenoestrogens have been extensively studied in rodents, generally under single, high-dose conditions. Using a continuous-release, low-dose system in ovariectomized mice, we correlated the estrogenic end points of uterine epithelial height (UEH) and vaginal epithelial thickness (VET) with concentrations of two organochlorine pesticide isomers in fat and blood. Silastic capsules containing a range of doses of either ss-hexachlorocyclohexane (ss-HCH) or o, p'-dichlorodiphenyltrichloroethane (o,p'-DDT) were implanted subcutaneously, and animals were killed after 1 week. Average blood levels achieved by the various doses were 4.2-620 ng/mL for o,p'-DDT and 5.0-300 ng/mL for ss-HCH. Fat concentrations of o,p'-DDT and ss-HCH correlated linearly to blood levels (o,p'-DDT, r(2) = 0.94; ss-HCH, r(2) = 0.83). Fat concentrations (nanograms per gram of tissue) were higher than blood concentrations (nanograms per milliliter) by 90 +/- 5- and 120 +/- 9-fold (mean +/- SE) for o, p'-DDT and ss-HCH, respectively. The VET ranged from 12 +/- 0.9 microm in controls to 114 +/- 8 microm in treated animals, and was correlated to blood levels of either treatment compound. The UEH ranged from an average of 7.7 +/- 0.3 microm in controls to 26 +/- 2 microm in high-dose o,p'-DDT-treated animals. The UEH was also correlated with ss-HCH concentration, but it plateaued at approximately 11 microm at the highest doses. The lowest blood concentrations that produced statistically significant increases in VET or UEH were 18 +/- 2 ng/mL o,p'-DDT and 42 +/- 4 ng/mL ss-HCH. These values are within the same order of magnitude of blood concentrations found in some human subjects from the general population, suggesting that human blood concentrations of these organochlorines may reach estrogenic levels.

Automated Toxaphene Quantitation by GC/MS.

Toxaphene is a complex mixture of at least 600 hexa- to decachlorinated bornanes and bornenes, which was used as an insecticide from the late 1950s to the early 1980s. Like PCBs and other environmentally persistent organochlorine pesticides, toxaphene is ubiquitous in the environment. Toxaphene's complex composition makes its accurate quantitation difficult. We report here an automatic, gas chromatographic mass spectrometry method (using electron capture negative ionization) that is precise and fast. This method is implemented by a small QBasic program that compares peak area ratios to the predicted chlorine isotopic ion ratios. This method decreases the time required for analysis while maintaining precise quantitation. The method is verified with standard and unknown samples contaminated with various amounts of other organochlorine pesticide interferents.

Space charge evaluation in a plasma-source mass spectrograph.

Space charge effects, and the matrix interferences they cause, are problems in inductively coupled plasma mass spectrometry (ICPMS). It has previously been observed that these deleterious space charge effects are not significantly present in sector-field instruments, a fact that has been attributed, but not demonstrated, to the high accelerating potentials they commonly employ. To examine the significance of space charge in our plasma-source mass spectrograph (which operates at only moderate accelerating potentials) and in other sector instruments, a graphite disk was placed approximately 7 cm behind the skimmer. An inductively coupled plasma was operated for 17 h while a 0.01 mM multielement solution was introduced. This disk was then analyzed by spatially resolved laser ablation ICP time-of-flight MS. Second vacuum-stage acceleration appears to be an important factor that governs the elemental distribution within the ion beam. The ion beam width at m/z 208 is one-third of its width at m/z 7 using an accelerating potential of 800 V; at an accelerating potential of 4000 V, the ion beam width does not vary with mass.

Global distribution of persistent organochlorine compounds.

The global distribution of 22 potentially harmful organochlorine compounds was investigated in more than 200 tree bark samples from 90 sites worldwide. High concentrations of organochlorines were found not only in some developing countries but also in industrialized countries, which continue to be highly contaminated even though the use of many of these compounds is restricted. The distribution of relatively volatile organochlorine compounds (such as hexachlorobenzene) is dependent on latitude and demonstrates the global distillation effect, whereas less volatile organochlorine compounds (such as endosulfan) are not as effectively distilled and tend to remain in the region of use.