Toxaphene Residues Research Articles

Residues of Toxaphene in Finfish and Shellfish from Terry and Dupree Creeks, Georgia, U. S. A.

To better characterize human health risks associated with potentially contaminated seafood, 56 composite samples of edible tissue of several finfish and shellfish species were analyzed for residues of toxaphene using gas chromatography with electron capture and negative ion mass spectrometric detection (GC-ECD and GC-ECNI-MS). Toxaphene in these samples, collected in 1997 near a former toxaphene plant in Brunswick, Georgia, were previously reported as non-detectable using non-selective techniques. Estimated total toxaphene concentrations (ΣTOX) ranged from less than 0.01 to 26 μ g−1 on a wet tissue basis. Smaller, bottom dwelling finfish such as croaker, mullet, and spot exhibited the highest ΣTOX (0.76–26 μg g−1), larger predatory fish including seatrout contained intermediate levels (0.08–4.4 μg g−1), and shellfish (blue crab and shrimp) contained the lowest levels (<0.01 to 0.27 μg g−1). For a given species, samples from the site furthest from the toxaphene plant had lower ΣTOX than samples from the other 3 sites. On a congener specific basis, levels ranged from <0.0025 to 3.5 μg g−1. Congener distributions were, in general, dominated by 2-exo, 3-endo, 6-exo,8,9,10-hexachlorobornane (Hx-Sed) and 2-endo,3-exo,5-endo,6-exo,8,9,10-heptachlorobornane (Hp-Sed), breakdown products of Cl8−Cl10 toxaphene homologs. Other prominent congeners confirmed by GC-ECNI-MS included Parlar numbers 26, 40/41, 42, 44, 50, 62, and 63, as well as several unidentified Cl6−Cl9 homologs. Minor differences in congener distribution among species and sampling locations suggested that exposure regimes and/or intrinsic biotransformation capabilities were not uniform. These results indicate that toxaphene residues were detectable in all species surveyed and at concentrations higher than estimated previously.

Toxaphene in the United States: 2. Emissions and residues

Emission factors of toxaphene for spraying and tilling events are distributed for the United States on a 1°×1° latitude and longitude grid system. By using the gridded usage and emission factors, inventories of gridded toxaphene emissions and residues in agricultural soil in the United States with 1/6°×1/4° latitude and longitude resolution have been created. Total toxaphene emissions were around 190 kt between 1947 and 1999. At the beginning of 2000, almost 20 years after banning the use of toxaphene, there were still around 29 kt of toxaphene left in the agricultural soil, of which 360 t will emit to the air in 2000. The calculated toxaphene emissions and residues are in general consistent with published monitoring data. The trends of toxaphene emissions due to current use and residues in agricultural soil in the United States match both the historical atmospheric input function for toxaphene extending over the past 40 years derived from the composition of toxaphene in peat core from eastern Minnesota to Nova Scotia, and the trends of air concentration of toxaphene in the Arctic. This indicates that toxaphene residues in the United States agricultural soil could be a major source of toxaphene in the Canadian Arctic and the Great Lakes region.

Toxicological consequences of toxaphene ingestion by cynomolgus ( Macaca fascicularis) monkeys. Part 1: pre-mating phase

A total of 40 menstruating cynomolgus monkeys ( Macaca fascicularis) with an average age of 7.25±1.06 years (standard deviation), five male cynomolgus monkeys with an average age of 12.6±0.66 years, and five male cynomolgus males with an average age of 6.2±0.23 years were obtained from the Health Canada breeding laboratory. The females were initially randomized to the four test groups in accordance with their previous reproductive success and body weight. They were then randomly allocated between two similar environmentally-controlled rooms (20 females/room). The males were randomly assigned to one of the test rooms (six or four males/room). The female test groups self-ingested capsules containing doses of 0, 0.1, 0.4 or 0.8 mg (Groups A, B, C, D) of technical grade toxaphene/kg body weight/day (i.e. five females/dose group/room). The older males (Group E) were proven breeders and were used exclusively for mating and their capsules contained no toxaphene. The younger males (Group F) ingested capsules containing 0.8 mg of technical grade toxaphene/kg body weight/day. After 20 weeks of daily dosing, it was assumed, based on the results of a pilot study [Andrews P., Headrick K., Pilon J.-C., Bryce F., Iverson F. (1996) Capillary GC–ECD and ECNI GCMS charcterization of toxaphene residues in primate tissues during a feed study. Chemosphere 32, 1043–1053], that the treated monkeys had attained a qualitative pharmacokinetic steady state regarding the concentration of toxaphene in their adipose tissue and blood. On a daily basis, each monkey's feed and water consumption as well as its health were monitored. In addition, the females were swabbed daily to determine menstrual status. On a weekly basis, each monkey's body weight was determined and its dose of toxaphene adjusted. Detailed clinical examinations were conducted at intervals of 4 weeks or less. Periodically, starting prior to the initiation of dosing, blood samples were taken for serum biochemistry, haematology and toxaphene analysis. In addition, specimens from the nuchal fat pad were also obtained for toxaphene analysis. Statistical analysis did not reveal any effect of treatment on body weight gain, feed consumption, water consumption or haematological parameters during the 75-week pre-mating phase. The only serum biochemistry parameter which was consistently affected by treatment was cholesterol, the level of which decreased in a linear fashion as a consequence of dose, and this effect increased with time on test ( P=0.037). No other biological effects of toxaphene ingestion were found during the premating phase of this toxicological–reproduction study.

Gas chromatographic separation of toxaphene residues by DB-XLB

Gas chromatographic separation of toxaphene residues by DB-XLB

Gas chromatographic separation of toxaphene residues by DB-xLB

Gas chromatographic separation of toxaphene residues by DB-xLB

Prominent chlorobornane residues in estuarine sediments contaminated with toxaphene

Soils and sediments contaminated with residues of technical toxaphene may require remedial action to reduce human health and ecological risks. Sediments were collected from a coastal wetland impacted by discharge from a former toxaphene production facility and analyzed by gas chromatography-electron capture detection and conventional and enantioselective gas chromatography-mass spectrometry in the electron capture negative ion mode. The prominent chlorobornanes (CHBs) in all samples were 2-exo,3-endo,6-exo,8,9,10-hexachlorobornane (B6-923 or Hx-Sed) and 2-endo,3-exo,5-endo,6-exo,8,9,10-heptachlorobornane (B7-1001 or Hp-Sed), metabolites of higher chlorinated components of technical toxaphene (CTTs). Pentachlorobornanes, toxaphene homologs not previously reported in environmental samples, and likely precursor CTTs were also detected. Several CHB congeners were enantioresolved, the majority of which exhibited racemic composition. These results indicate that the profile of CHBs persisting in estuarine sediment is highly modified relative to the technical mixture, and also provides strong evidence of in situ reductive dechlorination, a process that if enhanced could act to reduce bioaccumulation and toxicity of sediment-bound CTTs at toxaphene-contaminated sites.

Chlordane and Toxaphene Residues following Cooking of Treated Channel Catfish Fillets

The reduction in residues of chlordane and toxaphene following cooking (frying, baking, and smoking) of fillets obtained from treated Channel catfish (Ictalurus punctatus) was determined. On average, cooking reduced moisture content by 17% and increased fat content by 28 to 274%. Frying reduced chlordane residues by 56 to 86% on a dry basis (db) or 84 to 92% on a percent fat basis (fb) when raw fillets were compared to cooked fillets. Baking and smoking reduced chlordane significantly less (P < 0.05) than frying with reductions in residues of 12% and 9% (db) or 30% and 33% (fb), respectively. Frying reduced toxaphene residues by 40 to 49% (db) or 65 to 77% (fb), while baking and smoking reduced toxaphene by 35% and 24% (db) or 51% and 59% (fb), respectively.

Congener and Enantioselective Analysis of Toxaphene in Sediment and Food Web of a Contaminated Estuarine Wetland

Enantioselective gas chromatography with electron capture negative ion mass spectrometry (GC/ECNI-MS) was employed to investigate the fate of toxaphene residues in contaminated sediment (source) and biota (receptor) representing several levels of an aquatic food web. Samples were collected from an estuarine marsh that was impacted by discharge from a former toxaphene plant. Several penta- to nonachlorobornanes were identified and enantiomerically resolved on a chiral stationary phase. Additional peak confirmation was obtained after fine fractionation of extracts on silica. Previously identified congeners including B6-923 (Hx-Sed), B7-515 (P-32), B7-1001 (Hp-Sed), B8-806/9 (P-42), B8-1412, B8-1413 (P-26), B8-2229 (P-44), B9-1679 (P-50), and B9-2206 (P-63) were detected, as were several unknown penta- and heptachlorobornanes. The majority of prominent congeners were essentially racemic in marsh sediment (maximum deviation 15%). In contrast, several congeners as well as several unknown hepta-CTTs were enantioselectively depleted in lower food web organisms; the enantiomer ratios (ERs) for B6-923 and B7-1001 in small fish (Fundulus sp.) were ∼2 and 0.6, respectively. These significant alterations of the ERs prove that even low-trophic level biota is able to degrade toxaphene components to some degree. In higher level predators, the ERs for B7-1001 were closer to racemic. Irrespective of trophic level, little or no shift in the ERs for B8-1413 (P-26) and B9-1679 (P-50), two recalcitrant chlorobornanes in mammals, relative to sediment were observed. These results indicate that biochemical transformations within the scope of the estuarine food web studied likely act to alter the residue pattern and the ultimate fate of toxaphene.

Studies of toxaphene in technical standard and extracts of background air samples (Point Petre, Ontario) using multidimensional gas chromatography–electron capture detection (MDGC–ECD)

MDGC–ECD procedures have been used to provide insight into the compositional complexity of some of the specific peaks or clusters observed in the gas chromatographic analysis of a technical toxaphene standard, with reference to individual toxaphene congeners (Parlar # components) that are now commercially available. These investigations have focussed initially upon those peaks and clusters recently identified (Shoeib, M., Brice, K.A., Hoff, R., 1999. Chemosphere 39, 849–871) as dominant constituents of background ambient air. Multiple electron-capturing components have been found to be present in all the species studied: the available individual toxaphene congeners have been matched against these components where possible. In similar fashion, the responses obtained in equivalent gas chromatographic elution windows from the analysis of typical processed air sample extracts have been investigated, with the results showing clear differences relative to the patterns found in the technical toxaphene standard. In most cases, the air sample shows reduced complexity with fewer components present in the cluster. Also, the presence of interfering responses (due to PCBs and other organochlorines) is quite apparent and significant, showing that major problems and errors could arise when using single-column GC–ECD procedures for quantitation of toxaphene in environmental samples. The presence of certain of the Parlar species in the air samples has been confirmed and in most cases these represent the dominant toxaphene component found in the targeted cluster. Furthermore, the persistence of certain congeners in the atmospheric samples appears to be strongly dependent upon chemical structure, since the congeners in question possess an alternating exo–endo chlorine substitution pattern around the six-membered ring in the bornane skeleton. Such persistence is probably the result of lower metabolization of toxaphene residues in soils, water and sediments leading to a similar pattern in the atmosphere following volatilization.

The role of biotic and abiotic degradation processes during the formation of typical toxaphene peak patterns in aquatic biota

Toxaphene residues in cod liver and fish oil samples from different countries have been analyzed by HRGC-ECD and HRGC-MS as well as with multidimensional gas chromatography. The results have been compared to patterns obtained by photolysis and microbial degradation of selected single chlorobornanes and technical toxaphene. Enantiomeric ratios of the components Parlar #44 and #62 showed significant deviations from 1, indicating metabolism in cod fish and perhaps other species at least for some congeners. Parlar #50 was found to be a racemate, which corresponds to its known stability under biotic and abiotic conditions.

Toxaphene and other chlorinated compounds in human milk from northern and southern Canada: A comparison

Human milk from residents ofnorthern Canada (Keewatin) was compared to that in national surveys of southern Canada with respect to residues of toxaphene, PCBs, PCDD/PCDFs, chlordane, and several other persistant organic compounds. Concentrations of toxaphene were approximately ten-fold higher in specimens from Keewatin than from the south. Toxaphene concentrations in samples from the Great Lakes Basin collected in 1992 were not significantly (p<0.05) different from those of the rest of Canada; however they were significantly (p<0.05) lower than concentrations reported in a 1986 survey. Hexachlorobenzene, trans nonachlor and oxychlordane were three to five times higher in concentration in the Keewtin samples than in samples reported in the 1992 national survey. Total PCB congeners, DDTs, PCDD/PCDFs, and other chlorinated compounds were not significantly higher in northern samples.

The use of a microsomal in vitro assay to study phase I biotransformation of chlorobornanes (toxaphene®) in marine mammals and birds : Possible consequences of biotransformation for bioaccumulation and genotoxicity

The factors determining the bioaccumulation of lipophilic compounds in wildlife are often poorly understood, partly because it is difficult to do in vivo experiments with animals such as marine mammals and birds. To evaluate the role of phase I biotransformation in the bioaccumulation process of chlorobornanes (toxaphene®), this was studied in in vitro assays with hepatic microsomes of animals that could be sampled shortly after death. The capacity of microsomes to metabolise a technical toxaphene mixture decreased in the order Phoca vitulina (harbour seal)⪢ Lagenorhynchus albirostris (whitebeaked dolphin)≅ Diomedea immutabilis (Laysan albatross)> Physeter macrocephalus (sperm whale). Harbour seal microsomes metabolised the chlorobornane (CHB) congeners CHB-32 and CHB-62; whitebeaked dolphin and Laysan albatross microsomes only metabolised CHB-32. Metabolism of CHB-26 and CHB-50 was never observed. The negative chemical ionisation (NCI−) mass spectra of some of the hydroxylated metabolites were obtained. The number of peaks in the toxaphene residues of wildlife extracts decreased in the order of increasing in-vitro biotransformation capacity. Thus, the results of the in vitro assays and residue analysis were in accordance, although assays with microsomes of more individuals of the same species are required for a more general conclusion at the species level. Finally, the effect of in vitro biotransformation was evaluated in terms of the genotoxic potential using the Mutatox® assay. Only technical toxaphene and CHB-32 were genotoxic in the direct assay, whereas the addition of rat S9 fraction or microsomes of harbour seal and albatross decreased the genotoxic response. Thus, organisms with a low ability to metabolise chlorobornanes, such as whales, may be most affected by the carcinogenic properties of toxaphene. A hypothetical reaction which fits the experimental results is discussed. Based on these results it is concluded that in vitro assays with microsomes of wildlife animals which died a natural cause can act as a valuable tool to assess the occurrence and effects of phase I metabolism. Some precautions are discussed, that should be taken to reduce the chance of false negative results.

HRGC-ECD and HRGC-ECNI-SIM-HRMS quantification of toxaphene residues by six environmentally relevant chlorobornanes as standard

The HRGC determination of toxaphene residues in environmental samples is often difficult because of different degradation rates and accumulation behavior of individual toxaphene components. Therefore, isolated environmentally relevant chlorinated bornanes are used as standards. During the last years, single components as well as different combinations of them have been tested for their suitability for HRGC-HRMS-ECNI quantification. In this study, Parlar #26, Parlar #40, Parlar #41, Parlar #44, Parlar #50, and Parlar #62 have been used. The results show the sum of these six components to be at least 80–85% of toxaphene in fish oils.

Levels of toxaphene indicator compounds in fish meal, fish oil and fish feed

Three toxaphene indicator compounds were determined in fish oil and fish meal of different origin and raw material as well as in feed containing fish oil and fish meal. Fish oil and fish meal from South America contained no or only traces of the indicator congeners. The sum of the three compounds varied in fish oils from Europe between 13 μg/kg fat (sand eel oil) and 206 μg/kg fat (cod oil). Varying concentrations were also determined in European fish meal and in feed. Toxaphene indicator compounds were as well detected in trout and salmon fed with toxaphene residues containing feed. Results indicate that feed can contribute to toxaphene contamination of farmed salmon from Europe.

Determination of toxaphene in biological samples using high resolution GC coupled with ion trap MS/MS

Toxaphene remains as a pollutant of global concern because of its persistence in the environment. Its complex combination of congeners and the lack of individual standards makes accurate measurement of toxaphene residues in environmental samples a challenge. We have developed a novel method to measure toxaphene in environmental samples using ion trap MS/MS. Adequate sensitivity for analysis of biological samples such as fish and marine mammal blubbers were achieved (around 0.02 ppb to 0.06 ppb for individual congeners and 5.6 ppb for toxaphene mixtures). Accuracy was demonstrated by good recoveries of spiked toxaphene in corn oil samples (102% for toxaphene congeners at 4 ppb and 96% for toxaphene mixture at 139 ppb level). Results of analysis of toxaphene in cod liver oil (NIST SRM 1588) using the MS/MS method compared favorably with the median round robin interlaboratory data. The major advantage of the ion trap MS/MS over the existing methods; electron capture negative ionization mass spectrometer or electron capture detector, is its excellent selectivity. Interference from other organochlorines can virtually be eliminated. Therefore, the developed MS/MS method can be used as a reliable alternative to high resolution mass spectrometer for measurement of toxaphene in environmental samples with relatively low cost instrumentation.

PCB/Toxaphene group separation on silica prior to congener specific determination of toxaphene residues in fish and other samples by GC/ECD

A precise quantification of toxaphene residues of environmental samples by gas chromatography/ electron capture detection (GC/ECD) requires the separation of the bulk of the polychlorinated biphenyls (PCBs) from the compounds of technical toxaphene (CTT) fraction. For this reason, a PCB/CTT group separation on silica was developed 88-1413 (Parlay #26) and B7-515 (Parlay #32) eluted as first and last out of ten important CTT standards, and can be used to determine the elution volume of the CTT fraction on silica. GC/ECD quantification of CTTs was possible after separation of PCBs on 8.0 g activated silica eluted with 48 mL n-hexane followed by quantitative elution of CTTs with n-hexane/toluene (65:35; v/v). This method is a compromise between separation efficiency and consumption of material. Finally, eight CTTs were quantified in cod liver samples from Iceland and the Baltic Sea.

Levels of toxaphene indicator compounds in fish

Three toxaphene indicator compounds were determined in more than 100 samples of fish. The investigated fish included nearly all important fish species consumed in Germany. Highest residue concentrations were found in marine fish with high or moderate fat content, e.g. halibut, herring, redfish and mackerel. In fresh water species and marine fish with low fat content less contamination was found. A significant relationship between the fishing ground and the toxaphene residue could not established. Contamination levels of most species were related to the age (length) of the fish. The daily intake of total toxaphene in Germany was estimated at 2.8–5.6 ng/kg body weight.

Capillary GC-ECD and ECNI GCMS characterization of toxaphene residues in primate tissues during a feeding study

Toxaphene is a pesticide whose use was banned in North America because of concerns regarding its toxicity. To obtain better data on the metabolism and toxicity of toxaphene in primates, a one year feeding study was carried out in cynomologous monkeys at a dose of 1 mg/kg/day for one year. Levels of toxaphene residues in blood and adipose tissue during the dosing period were measured by GC-ECD and ECNI GCMS. The dosing toxaphene mixture was found to be extensively metabolized. Four chlorinated bornane congeners were the predominate residues found in the tissue samples. Blood levels of toxaphene residues plateaued at 40 ppb, adipose levels at approximately 4000 ppb. Kidney, liver, feces and urine were analyzed for toxaphene residues after necropsy.

Determination of toxaphene in soil by electron-capture negative-ion mass spectrometry and capillary column gas chromatography

Although toxaphene is now limited in use, interest in its analysis continues because of its persistence and widespread atmospheric transport in the environment and its presence in many dump-sites all over the world. Top soil samples collected from a dump site were analyzed for toxaphene residues. Analyses were performed by wall-coated open tubular column gas chromatography in tandem with electron-capture negative-ion mass spectrometry. Since the concentrations of toxaphene residues were at mg/kg levels, the application of a mass spectrometer as a substance-selective detector has been applied. Advantages of this mode of real-time acquisition in continuous repetitive scanning of mass spectra has significant advantages in comparison to the selected-ion monitoring technique. An average R.S.D. of 10% and recoveries of 90 to 109% were obtained. Levels down to 50 μg/kg are obtainable.

HRGC-ECD and HRGC-NICI SIM quantification of toxaphene residues in selected marine organism by environmentally relevant chlorobornanes as standard

The HRGC determination of Toxaphene R residues in fish tissues is often difficult because of the differing accumulation behaviour and decomposition rates of the individual Toxaphene compounds. This problem can satisfactorily be overcome by using purely isolated environmentally relevant chlorinated bornane derivatives (Parlar Nr. 26, 32, 50, 42, 69). The method is highly selective for measuring Toxaphene residues in complex marine organism matrices.