Retention time profiling of all 136 tetra- through octa- chlorinated dibenzo-p-dioxins and dibenzofurans on a variety of Si-Arylene gas chromatographic stationary phases

The applicability of three different Silphenylene Silicone co-polymer (Si-Arylene) GC stationary phases (J&W Scientific DB-5ms, Varian VF-5ms, and VF-Xms) has been evaluated for the separation of all 136 tetra- through the octa- chlorinated dibenzo-p-dioxins (PCDD) and chlorinated dibenzofurans (PCDF) from closely eluting isomers using gas chromatography/high resolution mass spectrometry (GC/HRMS). Their relative performance data are compared to the “conventional” 5% diphenyl 95% dimethylpolysiloxane GC column (Supelco Equity-5) and to each other based on absolute retention times, visualized mass chromatograms, and the separation of 2,3,7,8-substituted isomers. VF-Xms GC column was able to demonstrate a better performance towards separation of 2,3,7,8-substituted PCDD/PCDF compared to other Si-Arylene GC columns tested, where only 2,3,4,7,8-PnCDF can not be resolved from 1,2,3,6,9-PnCDF and 2,3,4,6,7,8-/1,2,3,6,8,9-HxCDF and 1,2,3,7,8,9-/1,2,3,4,8,9-HxCDF can be at least partially resolved. These data suggest that the development of a single GC column for the separation of all 17 2,3,7,8-substituted dioxins and furans is feasible, which therefore could be used as a standard tool for the PCDD/PCDF methods globally including USEPA methods 1613b, 8290A, 8280B, European Standard Method EN 1948, Canadian methods DFPCB-E3418, EPS 1/RM/19, Japanese methods JIS K0311 and JIS K0312. Having one specific GC column to separate all 2,3,7,8-substituted PCDD/PCDF will significantly improve the data quality, comparability by the various methods and assessment techniques while simultaneously leading to a more cost and time efficient operation.     

Development of GC capillary column for isomer-specific separation of toxic isomer of PCDDs and PCDFs in environmental samples

Analysis of polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) has been performed using gas chromatography mass spectrometry (GC-MS). Analysis of the most toxic isomers, in particular, 2,3,7,8-substituted PCDD/PCDF in the presence of other isomers requires a special isomer specific capillary column or high performance liquid chromatography (HPLC) fractionation prior to GC-MS analysis. Commercially available long (>50 m) polar columns can separate 2,3,7,8-TCDD from other tetra isomers. However, those columns are not satisfactory for the analyses of total PCDD/PCDF in the environmental samples. Gas chromatography -high resolution mass spectrometry (GC-HRMS) and GC-MS/MS techniques are not helpful in the analysis of 2,3,7,8-TCDD unless it is separated from the other tetra isomers. The analysis of 2,3,7,8-TCDD and total PCDD and PCDF in a single GC-MS run can ease the laborious techniques presently used. In this study we have developed a new stationary phase for the GC capillary column. The capillary column developed using this new stationary phase showed unsurpassed selectivity for the separation of 2,3,7,8-TCDD from other tetra isomers. There are several advantages of the newly developed GC capillary column.     

Application of the new C18 speedisks to the analysis of polychlorinated dibenzo-p-dioxins and dibenzofurans in water and effluent samples

A recently introduced disk for solid-phase extraction of pollutants from water (C18 Speedisk) has been tested for the analysis of polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF). The complete procedure of analysis has been validated with spiked deionized water. The accuracy, expressed as recovery for the sum of 2,3,7,8-substituted congeners. is 92% and the precision, expressed as the RSD of reproducibility, is 5.8%. The limit of detection (LOD), using 2 l of water, is 4.2 pg/l (0.6 pg ITEQ/l) for the sum of 2,3,7,8-substituted congeners. Actually, the C18 Speedisks have substituted the use of other C18 membrane disks in our laboratory because they allow the fast and efficient analysis of samples with high content of suspended material and reduce the time of elution of free-particulate samples. These disks have been successfully applied to the analysis of water from different sources and with very different physical and chemical characteristics: seawater, rain water, an industrial effluent, a landfill leachate and the inlet and chlorinated and non-chlorinated outlet water from a wastewater treatment plant.     

Systematic analysis and overall toxicity evaluation of dioxins and hexachlorobenzene in human milk

A systematic method for analyzing dioxins (PCDDs, PCDFs and dioxin-like PCBs), hexachlorobenzene (HCB), heptachlor epoxide and beta-hexachlorocyclohexane (HCH) in human milk was developed to determine the residual amount of HCB in human milk and to evaluate the overall toxicity of both dioxins and HCB in human milk. The fractionation behavior of HCB on chromatography with silica gel, alumina, and activated carbon/silica gel, and the concentrated sulfuric acid decomposition method, which is widely used as a dioxin cleanup method, were studied in order to make the preprocessing operation for HCB measurement compatible with that for conventional dioxin measurement. HCB was found to be eluted in the 2% dichloromethane (DCM)/hexane 60 ml fraction from an alumina column. Heptachlor epoxide and a part of beta-HCH were eluted in the 10% DCM/hexane 50 ml fraction from a silica gel column, while the remaining beta-HCH was eluted in the 25% DCM/hexane 60 ml fraction from an activated carbon/silica gel column. Moreover, HCB showed significant correlation with dioxin congeners having high toxicity equivalence factors (TEFs). The results suggest that the exposure route to HCB and its accumulation behavior in the human body are similar to those of the dioxins.     

Sorbent-assisted liquid-liquid extraction (Chem-Elut) of polychlorinated biphenyls, dibenzo-p-dioxins and dibenzofurans in the lipid fraction of human blood plasma

This work compares two lipid extraction methods for determining 24 polychlorinated biphenyls (PCBs), seven dibenzo-p-dioxins (PCDDs) and ten dibenzofurans (PCDFs) in human blood plasma. The first method was based on conventional liquid-liquid partitioning with chloroform-methanol and the other made use of a sorbent (Chem-Elut) to facilitate the partitioning of lipids into a mixture of hexane and 2-propanol. A multi-layer-silica column including acid- and base-impregnated silica gel was used to reduce the amounts of lipid present in the samples before a basic alumina clean-up step and activated carbon fractionation of planar analytes (PCDD/Fs and non-ortho-PCBs) and non-planar analytes (including ortho-chlorinated PCBs). Gas chromatography coupled to high resolution mass spectrometry was used to identify and quantify the analytes in the two fractions. The wet weight based concentrations obtained by the two methods were in agreement but both methods suffer from large organic solvent consumption. The toxic equivalencies derived for PCBs and PCDD/Fs using the two methods were also in agreement. However, the chloroform-methanol method gave slightly higher lipid recoveries, although with greater variation, than the sorbent-assisted method. Nevertheless, despite giving lower lipid recoveries, the sorbent-assisted method has advantages in ease of use and applicability to whole blood samples. The formation of emulsions was avoided with the Chem-Elut method, which probably explains the lower variability in the lipid determinations.     

Abundance and sources of ambient dioxins in Hong Kong: a review of dioxin measurements from 1997 to 2001

Ambient measurements of seventeen 2,3,7,8-polychlorinated dibenzo-p-dioxin/dibenzofuran congeners (2,3,7,8-PCDD/Fs) have been taken in a number of monitoring programs or ad-hoc studies in Hong Kong. The longest monitoring program started at two locations in the territory in July 1997. The other monitoring efforts are ad-hoc studies, varying from a few coordinated sampling events at multiple sites to a year-long monitoring project that targeted suspected local dioxin sources. In this paper, we examined these measurements to understand the ambient levels, temporal and spatial variation, and possible sources of the 2,3,7,8-PCDD/Fs in Hong Kong. The territory-wide annual average concentration of the dioxins was 0.052 pg I-TEQ/m3 measured at the regular monitoring stations in the most recent annual cycle of 2000/2001. This level fell at the lower end of the range of dioxin concentrations measured at other urban locations around the world. The dioxin levels showed a clear seasonality in that elevated concentrations were observed in the winter and lower concentrations in the summer at all monitoring sites with one year or more regular measurements. The measurements indicated that the few known local dioxin sources, including a major chemical waste incinerator facility, landfill sites, and vehicular traffic, are not important contributors to ambient dioxins in Hong Kong. On days of high dioxin concentrations, the 2,3,7,8-PCDD/F congeners were observed to have almost identical compositions with a north-northwest to south-southeast spatial gradient in concentrations at different sampling locations in Hong Kong. This observation, along with other collaborative evidence, established a strong link between high dioxin concentration days in Hong Kong and regional transport of the polluted air masses from the north.     

Minimization of blank values of the miniature silica gel column

Several methods involving silica gel separations of polychlorinated biphenyls from chlorinated insecticides are already described in literature. Our intention was to find a system of solvent and silica gel of the lowest blank values. The first step was to find a solvent mixture which will keep the homogenity of a silica gel column. PCBs elution was performed with pentane, while the chlorinated insecticides eluated with diethylether, acetone, methanol, and benzene. The elution of pesticides gave the best results for the following solvent systems: diethylether + hexane (1:1), acetone + hexane (1:4), methanole + pentane (1:8) and benzene.Separation of pesticides from polychlorinated biphenyls found in a synthetic mixture was also examined. It was found that all solvent systems used gave similar results of separation. However, only if benzene is used as eluant, the silica gel column can be used for four successive separations after the “on column” regeneration. In order to obtain the lowest blank values silica gel was cleaned with several solvents. The eluates after the silica gel separation were also cleaned up by means of deactivation alumina and concentrated sulphuric acid.     

Regional measurements of PCDD/PCDF concentrations in Korean atmosphere and comparison with gas-particle partitioning models

The current investigation was aimed at determining the levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDFs) in the Korean atmosphere along with their estimation using gas-particle partitioning. Samples collected from six cites showed that large cities were polluted with a concentration of 0.593 pg TEQ/m3. Samples were also collected from residential (nine sites), commercial (five sites), and industrial (seven sites) districts in each city. Higher levels of PCDDs/PCDFs were observed in industrial area than other areas, since it includes many sources. Higher chlorinated 2,3,7,8-substituted congeners were predominantly found in the particulate phase. HpCDD/Fs and OCDD/Fs shared 97-99% of the particulate phase, whereas TCDD/Fs, which dominated the gaseous phase, shared 34.8% and 42.8% in 2,3,7,8-substituted congeners. The regression dataset was transformed due to the relationship between log K(P) and log P(L)o. A wide variation was observed in the slopes for the residential areas when compared with the slopes for the commercial and industrial areas. The Junge-Pankow model and K(oa) adsorption model were both found to be helpful in describing the gas-particle partitioning in the current study.     

Separation of non-ortho polychlorinated biphenyl congeners on pre-packed carbon tubes. Application to analysis in sewage sludge and soil samples

The analysis of planar (non-ortho) polychlorinated biphenyls (PCB) by HRGC-ECD or HRGC-HRMS requires a fractionation step to avoid the interferences of the bulk of PCB, usually in much higher concentration than the planar ones. In this paper, a new method, based on the fractionation of PCB on SPE commercial tubes pre-packed with Carbopack B, has been developed. After the extract has been applied on the stationary phase, the bulk of PCD are eluted with 15 ml of hexane (fraction I), mono-ortho PCB with 20 ml of hexane/toluene 99:1 (fraction II) and planar PCB with 20 ml of toluene (fraction III) in a station under vacuum. The method has been validated: accuracy (expressed as recovery in %) is >70% and precision (expressed as % RSD) is <20% considering changes of day, analyst and batch of tubes. The method is linear in the range studied. Other advantages are that the method is simple, rapid and it can be easily automated. The application of this separation to the determination of planar PCB in fly-ash extracts from an intercalibration exercise and to sewage sludge, sediment and soil samples has been successful. In addition, this method removes hydrocarbons from the planar PCB fraction and allows its concentration to very small volumes.     

Contamination of fish by 2,3,7,8-tetrachlorodibenzo-P-dioxin: A survey of fish from major watersheds in the United States

A survey of contamination of fish from major watersheds in the United States by 2,3,7,8-TCDD has been conducted by the U.S. EPA. Bottom feeding and predator fish were collected at 90 statistically selected and 305 regionally selected sites and analyzed by GC/MS. It was found that 19% of the statistically sampled sites and 31% of the regionally selected sites were contaminated at or above a minimum level of detection varying from 0.5 to 2.0 pg/g. Ten percent of all samples were contaminated at levels greater than 5.0 pg/g. It was also observed that a subset of samples collected at sites near discharge from pulp/paper manufacture (N=28) had a higher frequency of TCDD contamination above 5.0 pg/g (38%). This subset of samples also contained the sample of the greatest level of TCDD contamination (85 pg/g).     

Development and validation of a method for analysis of "dioxin-like" PCBs in environmental samples from the steel industry

A method, previously used for determination of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), has been modified for quantitative analysis of "dioxin-like" polychlorobiphenyls (PCBs) in environmental samples from the steel industry. The existing sample clean-up procedure, involving liquid chromatography on multi-layered silica and Florisil columns, has been extended to include a third chromatography stage on a basic alumina stationary phase. The additional clean-up stage is required for PCB analysis in order to eliminate interferences from relatively large concentrations of saturated cyclic and aliphatic hydrocarbons. Samples were analysed for WHO-12 congeners using high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) and standard solutions of the method US EPA 1668A. Replicate analysis of method blanks revealed background contamination for PCBs 118, 105 and 77, which are generally abundant in ambient air. These contaminants were taken into account using a subtraction method. The entire procedure was validated by replicate analysis (N = 3) of a certified reference sediment. The RSD for each WHO-12 congener was below 15%, 13C12-labelled PCB internal standard recoveries were in the range 70-95%. A waste dust sample collected in the electrostatic precipitator of a UK sinter plant was analysed for determination of PCDD/Fs and WHO-12 PCBs and exhibited a PCDD/F I-TEQ of 148.5 +/- 21.2 ngkg(-1) and a WHO-TEQ of 7.2 +/- 1.5 ngkg(-1). WHO-12 congeners contributed only 4.6% to the overall TEQ and PCB 126 was the major congener contributing to the WHO-TEQ (96%). The contribution to the overall TEQ of the waste dust sample was mainly attributed to PCDF followed by PCDD, which accounted for 86.6% and 8.7% to the overall TEQ, respectively.     

Natural products: repellency and toxicity of wild tomato leaf extracts to the two-spotted spider mite, Tetranychus urticae Koch

The potential of using phytochemicals from leaves of wild tomato for controlling the two-spotted spider mite, Tetranychus urticae Koch, is explored in this study as a promising alternative to the use of synthetic pesticides. Wild tomato accessions of Lycopersicon hirsutum plants that are not consumed by humans were planted under greenhouse conditions for mass production of leaves. Crude extracts from leaves of three accessions of L. hirsutum, six accessions of L. hirsutum f. glabratum, and one accession each of L. pennellii and L. pimpinellifolium were prepared in chloroform, ethanol and hexane. Two spider mite bioassays, one a measure of antibiosis and the other a measure of repellency, were utilized to determine the acaricidal performance of the crude extracts. The bioassay for antibiosis was a 6-h no-choice test. The bioassay for repellency utilized a ring bioassay. Chloroform leaf extracts of L. hirsutum f. glabratum accessions (PI-251304, PI-134417, PI-134418, and PI-126449) exhibited greatest antibiotic activity on two-spotted spider mites; the hexane extracts exhibited greatest repellency. Extracts from PI-251304, PI-126449, PI-134417, and PI-134418 were especially lethal (chloroform) or repellent (hexane). We investigated differences in chemical composition of the crude leaf extracts that may explain the observed differences in mortality and repellency among the different accessions. Major chemical compounds (alpha -curcumene, alpha -zingiberene, trans-caryophyllene, 2-undecanone, and 2-tridecanone) known to have pesticidal efficacy were detected and quantified in the crude leaf extracts using a gas chromatograph (GC) equipped with a mass spectrometer (GC/MS). Lethality of extracts was mainly associated with the presence of high concentrations of 2-tridecanone; repellency of extracts was mainly associated with the presence of trans-caryophyllene. Leaf extracts of L. hirsutum f. glabratum accessions that contain significant quantities of 2-tridecanone and/or trans-caryophyllene could be useful for managing populations of spider mites, which could reduce reliance on synthetic pesticides.     

Nationwide study of dioxins in the freshwater fish Carassius auratus (gibelio) langsdorfii (crucian carp) in Japan: concentrations and estimation of source contribution ratios

We investigated dioxin concentrations in freshwater fish in Japan by standardizing species to detect subtle decreasing trends of dioxin concentrations in the future with the reinforcement of regulations. The fish studied were crucian carp (Carassius auratus (gibelio) langsdorfii), an omnivorous species. Fish and sediments were collected from 14 rivers and lakes located in remote areas, agricultural areas, and small and large cities throughout Japan. The total toxic equivalent (TEQ) dioxin concentrations at the three remote sites were about 20% of the concentrations at the other 11 sites, which all had similar concentrations. The average concentrations in fish collected from these 11 sites were 0.69pgTEQg(-1) wet wt. (95% CI 0.52-0.85) or 57.3pgTEQg(-1) fat (95% CI 47.9-66.7). There were notable differences in congener profiles of polychlorinated p-dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) between sampling areas. A chemical mass balance method was used to estimate the proportions of dioxin contributions from different sources. The sampling areas were classified into four groups on the basis of the predominant source of dioxin contamination: a combustion group, a chlornitrofen herbicide group, a chlornitrofen and pentachlorphenol herbicide group, and a remote group. The congener profiles of dioxin like polychlorinated biphenyls (DL-PCBs) were almost the same in all areas and close to those in Kanechlor, which indicates that pollution from PCB products has spread throughout Japan. From samples collected during the spawning season, it was determined that about 20% of the dioxins in adult females were transferred to the eggs, resulting in higher dioxin concentrations in adult males than in females. Biota-sediment accumulation factors (BSAFs) of 2,3,7,8-substituted PCDDs/DFs for crucian carp were larger than those of non-2,3,7,8-substituted congeners, and BASFs decreased with increasing number of chlorines. The BSAFs of DL-PCBs were 10 times greater than those of PCDDs/DFs, and BSAFs of mono-ortho type DL-PCBs were higher than those of non-ortho types.     

Qualitative and quantitative cancer risk assessment of 2, 3, 7, 8-tetrachloro-dibenzo-p-dioxin (2, 3, 7, 8-TCDD)

The carcinogenicity of 2,3,7,8-TCDD at multiple organ sites in animals has been well established by several cancer bioassays. Results of two of the most notable of these, the Kociba et al. (1978) rat feeding study and the National Toxicology Program (1980) gavage study in rats and mice showed hepatocellular carcinomas in two strains of female rats and male and female mice. Other tumor sites included carcinomas of the lung, tongue, hard palate and nasal turbinates, thyroid, and subcutaneous tissue. The evidence for carcinogenicity of 2,3,7,8-TCDD in animals is regarded as “sufficient” using the classification system of the International Agency for Research on Cancer (IARC).

Two Swedish epidemiologic case-control studies (Hardell and Sandstrom, 1979; Eriksson et al. 1979, 1981) reported a significant five- to sevenfold excess risk of soft-tissue sarcomas (STS) from occupational exposure to chlorinated phenoxyacetic acid herbicides and/or chlorophenols. Additionally, several small cohort studies collectively exhibited an unusual cluster of STS, significantly increased over combined expected incidence. Problems with these studies do not appear to be sufficient to discount this excess risk. The human evidence alone for the carcinogenicity of 2,3,7,8-TCDD is “inadequate” using the IARC classification. However, for 2,3,7,8-TCDD in combination with chlorinated phenoxyacetic acid herbicides and/or chlorophenols, the human evidence is considered to be “limited.” The overall evidence for carcinogenicity considering both animal and human studies would place 2,3,7,8-TCDD alone in the IARC category 2B, meaning that the substance is probably carcinogenic in humans. The overall weight of evidence for 2,3,7,8-TCDD in combination with chlorinated phenoxyacetic acid herbicides and/or chlorophenols is regarded as IARC category 2A, also meaning that they are probably carcinogenic for humans.

Using current EPA methodology for quantitatively estimating cancer risks, several animal data sets have been analyzed. Comparing the results, the upper-limit incremental unit risk estimate is 1.6 × 10⁻² for a lifetime exposure of 1 ng/kg/day. This estimate is derived from a lifetime feeding study (Kociba et al., 1978) in which 2,3,7,8-TCDD induced tumors of the liver, lungs, hard palate, and nasal turbinates in female rats. Incremental unit cancer risks are also extrapolated for lifetime 2,3,7,8-TCDD exposures in water and air. Based on continuous lifetime exposure to 1 ng/L 2,3,7,8-TCDD in drinking water, the upper-limit estimate of extra cancer risk per individual is 4.5 × 10⁻³. For lifetime exposure to 1 pg 2,3,7,8-TCDD/m³ in the ambient air, the upper-limit individual risk is 3.3 × 10⁻⁵.     

Chlorinated dibenzo-p-dioxin and dibenzofuran levels in human adipose tissue and milk samples from the north and south of Vietnam

Although 2,3,7,8-TCDD has been found to be extremely toxic to a variety of laboratory aminals, human epidemiology studies, where exposure to 2,3,7,8-TCDD has been less well characterized than in animal toxicologic studies, have been less conclusive in characterizing the extent of toxicity. In order to determine whether the newly refined techniques of human adipose tissue biopsy including isomer specific and sensitive measurement of PCDDs and PCDFs might be able to assist in finding populations within the same country with high and low levels of dioxins, adipose tissue samples were taken and levels analyzed from the north and south of Vietnam. It seemed reasonable, based on previous work, that high levels of 2,3,7,8-TCDD might still be found in adipose tissue in selected patients living in areas sprayed with Agent Orange and other 2,3,7,8-TCDD containing herbicides, and that lower levels should be found in patients not exposed to 2,3,7,8-TCDD from herbicides or other sources, such as persons who had always resided in the north of Vietnam. Of 9 specimens from patients hospitalized in Hanoi who had never been south, none had detectable adipose tissue levels of 2,3,7,8-TCDD at a detection limit of 2 or 3 ppt on a wet weight basis. Of 15 specimens from Ho Chi Minh City hospitalized patients the mean of positive specimens (12 of 15) was 28 on a lipid basis. The mean of the positive values from the south is about 2 to 3 times higher than found in the North American Continent control patients where the mean is about 6–10 ppt and much higher than in the north of Vietnam. In the northern specimens, the levels were non-detectable with a sensitivity of between 2 and 3 ppt. Other PCDD and PCDF isomers not found in Agent Orange, the penta- through octachlorinated dibenzo-dioxins and dibenzofurans, were similar in isomer type and quantity in the south of Vietnam to what we previously reported in North America. Adipose tissue from the north of Vietnam contained the lowest levels of four through eight chlorinated dioxins and furans thus far reported. The initial data suggests that populations exist in the south of Vietnam with elevated levels of 2,3,7,8-TCDD at the present time, fourteen years after the last known 2,3,7,8-TCDD (Agent Orange) application, superimposed on a preexisting body burden of dioxins and dibenzofurans from sources other than Agent Orange such as technical grade pentachlorophenol or products of incineration contaminated with higher chlorinated PCDDs or PCDFs. In light of the recent finding that unexpected levels of PCDDs and PCDFs exist in the general adult population of industrialized countries, ca. 1,000 to 1,200 ppt, wet weight of total dioxin and furan isomers in adipose tissues, it seems reasonable that the extent of human toxicity of dioxins may be more readily characterized in Vietnam than in industrialized countries. Because 2,3,7,8-TCDD was applied in 1962–1970, although not yet cleaned up, the levels of 2,3,7,8-TCDD in the environment, the food chain, and in humans, would be expected to decrease with time. Therefore, if studies are not initiated in a timely fashion, the opportunity to better characterize the extent of the toxicity of TCDD to humans as well as the persistence of TCDD in the environment in Vietnam may be lost.     

Dioxin formation in pulp and paper mills of India

Samples of effluents, sludge, pulp, final products (paper) and soil were collected from the identified pulp and paper mills in India. The samples were analysed for 2,3,7,8-tetrachloro-dibenzo-p-dioxin (2,3,7,8-TCDD) and other dioxin congeners and precursors. Pulp and paper mills using chlorine for the bleaching process showed the presence of 2,3,7,8-TCDD in effluent samples. In the effluent and pulp samples from mills where chlorine dioxide was used as a bleaching agent, the 2,3,7,8-TCDD congener ranged from below the detection limit 0.05 to 0.12 ngL⁻¹/ngg⁻¹. The relative standard deviation of reproducibility and the percent recovery of 2,3,7,8-TCDD were 2.07 and 82.4% in pulp and 2.8 and 92% in effluent, respectively. The 1,3,6,8-TCDD was the only other major dioxin congener found in the treated and untreated effluent and sludge samples. However, dichlorobenzene, trichlorophenyl, and hexachlorobiphenyl were detected in all samples. The formation of dioxins can be minimised by replacing chlorine with chlorine dioxide in bleaching processes in pulp and paper mills.     

The relationship between hydrogen and sulphate ions in precipitation-A numerical analysis of rain and snowfall chemistry

Acidic rain has been identified as potentially harmful to the aquatic and terrestrial components of the ecosystem. Sulphate measured in rain and snow has been used as a surrogate indicator of acidic deposition. If sulphur dioxide controls are the means to limit acidic deposition, then the association between sulphate and hydrogen ion concentrations in precipitation is an important factor in establishing such limits. Selected data on rain and snowfall chemistry from the National Atmospheric Deposition Program (NADP), the Electric Power Research Institute's SURE, the utility industries' UAPSP, and the Department of Energy's MAP3S were reviewed. Numerical analyses were performed to assess the relationship between hydrogen and sulphate ion concentrations. The strength of the association between hydrogen and sulphate ions varied from site to site. In the Midwestern and Eastern regions, the Pearson correlation coefficient was over 0.50 while in the Central and Upper Midwestern parts of the United States, the correlation coefficients were less than 0.25. Regardless of the strength of the association between hydrogen and sulphate ions, all but one of the NADP/NTN sites used in our analysis exhibited at least 30% of the anions (sulphate, nitrate, and chloride) associated with cations other than hydrogen. For sites where the strength of the association was weak, between 65% and 98% of the anions appeared to be associated with cations other than hydrogen. Because a large percentage of the anions (i.e. sulphate, nitrate, and chloride) appear to be associated with cations other than hydrogen even at those sites where the association between hydrogen and sulphate ions was strong, the complex chemistry controlling the acidity in precipitation may make it difficult to predict the impact of a reduction in sulphate concentration.     

Natural Products: Repellency and Toxicity of Wild Tomato Leaf Extracts to the Two-Spotted Spider Mite,Tetranychus urticae Koch

The potential of using phytochemicals from leaves of wild tomato for controlling the two-spotted spider mite, Tetranychus urticae Koch, is explored in this study as a promising alternative to the use of synthetic pesticides. Wild tomato accessions of Lycopersicon hirsutum plants that are not consumed by humans were planted under greenhouse conditions for mass production of leaves. Crude extracts from leaves of three accessions of L. hirsutum, six accessions of L. hirsutum f. glabratum, and one accession each of L. pennellii and L. pimpinellifolium were prepared in chloroform, ethanol and hexane. Two spider mite bioassays, one a measure of antibiosis and the other a measure of repellency, were utilized to determine the acaricidal performance of the crude extracts. The bioassay for antibiosis was a 6-h no-choice test. The bioassay for repellency utilized a ring bioassay. Chloroform leaf extracts of L. hirsutum f. glabratum accessions (PI-251304, PI-134417, PI-134418, and PI-126449) exhibited greatest antibiotic activity on two-spotted spider mites; the hexane extracts exhibited greatest repellency. Extracts from PI-251304, PI-126449, PI-134417, and PI-134418 were especially lethal (chloroform) or repellent (hexane). We investigated differences in chemical composition of the crude leaf extracts that may explain the observed differences in mortality and repellency among the different accessions. Major chemical compounds (α -curcumene, α -zingiberene, trans-caryophyllene, 2-undecanone, and 2-tridecanone) known to have pesticidal efficacy were detected and quantified in the crude leaf extracts using a gas chromatograph (GC) equipped with a mass spectrometer (GC/MS). Lethality of extracts was mainly associated with the presence of high concentrations of 2-tridecanone; repellency of extracts was mainly associated with the presence of trans-caryophyllene. Leaf extracts of L. hirsutum f. glabratum accessions that contain significant quantities of 2-tridecanone and/or trans-caryophyllene could be useful for managing populations of spider mites, which could reduce reliance on synthetic pesticides.     

Tetrachlorodibenzo-p-dioxins and tetrachlorodibenzofurans in Atlantic coast striped bass and in selected Hudson River fish,waterfowl and sediments

In striped bass samples from the lower Hudson River and its estuary 2,3,7,8-tetrachlorodibenzo-$\text{p}$-dioxin (2,3,7,8-TCDD) was found at concentrations from 16 to 120 pg/g (ppt). Striped bass from two other locations (Rhode Island coastal waters and Chesapeake Bay, Maryland) had <5 ppt, 2,3,7,8-TCDD. The contaminant, 2,3,7,8-tetrachlorodibenzofuran (2,3,7,8-TCDF), was found in striped bass from all three locations with concentrations varying from 6 ppt in Chesapeake Bay to 78 ppt in the Hudson River. Results from a limited number of non-migratory fish (carp and goldfish) and sediments suggest that the upper Hudson River is not a source for 2,3,7,8-TCDD/2,3,7,8-TCDF contamination of striped bass.     

PCDD/PCDF formation in the chlor-alkali process—laboratory study and comparison with patterns from contaminated sites

Studies on the formation of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) during the electrolysis of sodium chloride solution (brine) using graphite or titanium electrodes were carried out at a laboratory scale. High concentrations of PCDFs but no PCDDs were formed in tests using graphite electrodes. With titanium electrodes, PCDFs were only formed when tar pitch was added and mainly originated from the dibenzofuran present in the tar. For the first time, a detailed assessment of the formation of mono- to octachlorinated PCDD/PCDF from tar pitch was investigated. The assessment included of the chlorination steps proved that PCDFs were formed by successive lateral chlorinated from dibenzofuran to MonoCDFs, DiCDFs, and TriCDFs to form the typical known “chlorine pattern” of TetraCDF to OctaCDF with a dominance of 1,2,7,8- and 2,3,7,8-TetraCDFs, 1,2,3,7,8-PentaCDF, and 1,2,3,4,7,8-HexaCDF as marker congeners. The final homologue distributions depended on reaction time and reaction temperature. In addition, electrolysis with non-chlorinated dibenzo-p-dioxins, dibenzofuran, and biphenyl was carried out. As a result, PCDDs, PCDFs, and PCB were formed at comparable yields. Congener patterns in soil samples from a PCDD/F-contaminated site where chlor-alkali electrolysis had been operated for decades in Japan had identical isomer distribution demonstrating the source and contamination potential and risk of these processes. Therefore, sites where in the past 120 years chlor-alkali electrolysis has been operated or where residues from chlor-alkali production or other chlorine using industries have been disposed should be assessed for their pollution level and exposure relevance. The assessment of total organohalogen content revealed that PCDF is only a small fraction of organohalogens in the contaminated soils. For an appropriate risk assessment, also other chlorinated aromatic compounds such as PCBs or PCNs need to be considered.