Determination of the toxic impurities 3,3′,4,4′-tetrachloroazobenzene and 3,3′,4,4′-tetrachloroazoxybenzent in commercial diuron, linuron and 3,4-dichloroaniline samples

Methods are described for the determination of 3,3′,4,4′-tetrachloroazobenzene (TCAB) and 3,3′,4,4′-tetrachloroazoxybenzene (TCAOB) in diuron and linuron formulations and in 3,4-dichloroaniline. The formulations were extracted with acetone, and after removal of solvent, the residue was partitioned between methanol-water and hexane. 3,4-Dichloroaniline products were partitioned between methanol-1M hydrochloric acid and hexane. The hexane extracts were purified by column chromatography on silica gel and analysed by gas chromatography with electron-capture detection. Detection limits for TCAB and TCAOB were around 0.1 ug/g using samples of one gram. Levels of 5.5 – 28 ug TCAB and 1.9 − < 0.05 ug TCAOB/g herbicide formulation and 2.4 – 460 ug TCAB/g TCAB/g 3,4-dichloroaniline have been found. TCAOB levels were below the detection limits in the 3,4-dichloroaniline samples. The presence of TCAB and TCAOB was confirmed by gas chromatography-mass spectrometry.     

Synthesis of 4,4′-dichloro-3,5,3′,5′-tetramethylbiphenyl by the sandmeyer reaction

4,4′-Dichloro-3,5,3′,5′-tetramethylbiphenyl was prepared by -diazotization of 3,5,3′,5′-tetramethylbenzidine followed by the Sandmeyer reaction. The starting material is a noncarcinogenic analogue of benzidine, and the product may be of interest as a model compound for studying the metabolism of chlorinated biphenyls.     

Bioconcentration kinetics of 2,4,5- tri- and 3,3′,4,4′-tetrachlorobiphenyl and 2,4,5- tri- and 3,3′,4,4′-tetrachlorodiphenylether in fish

The rates of uptake and elimination of 2,4,5 tri- and 3,3′,4,4′-tetrachlorodiphenylether in fish after aqueous exposure are comparable to those of similarly substituted chlorobiphenyls. Mass balance data suggest that 2,4,5- trichlorobiphenyl and 2,4,5- trichlorodiphenylether are metabolized with rates approximately twice as high as the rates of elimination of the parent compounds.The bioconcentration factors of the 3,3′,4,4′-tetrachloro- biphenyl and 3,3′,4,4′- tetrachlorodiphenyl ether are only determined by the hydrophobic nature of these chemicals and are not influenced by metabolism. Congener specific uptake and elimination processes as have been reported for chlorinated dibenzo-p-dioxins and dibenzofurans does not seem to be important for chlorinated biphenyls and diphenylethers.     

3,3′,4,4′-Tetrachlorobiphenyl in human fat and milk samples

Samples of adipose tissue from 7 male persons and 10 samples of human milk were analyzed for 3,3′,4,4′-tetrachlorobiphenyl by HRGC-HRMS. The levels found are in the lower ppt-range on a fat weight basis     

Interactions of 2,2′,4,4′,5,5′-hexachlorobiphenyl and 2,3,7,8-tetrachlorodibenzo-p-dioxin in a subchronic feeding study in the rat

Female (SD) rats were fed diets containing 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB 153) in various concentrations for three months. PCB 153 had no significant effect on the body weight gain when given alone or in combination with TCDD. The increases in relative liver weights were additive. For thymic atrophy no interactive effects became apparent. PCB 153 had no effect on the EROD induction by TCDD. PROD induction by PCB 153 was diminished in the presence of TCDD. The level of TCDD in the liver was decreased by PCB 153. Increasing TCDD dosage led to an increase in PCB 153 levels.     

Levels of 3,3′,4,4′-tetrachloroazobenzene in herbicides and bulk reagents

The contamination levels of different commercial herbicides and bulk reagents with the carcinogen 3,3′,4,4′-tetrachloroazobenzene (TCAB) were determined by high resolution mass spectrometry. The concentrations vary from 0.00071 to 2.8 ug/g (ppm) for the herbicides and from 0.085 to 14 ug/g for the bulk reagents. They are thus lower than those of other reports.     

Toxicological evaluation of sulfur-containing metabolites of 2,5,2′,5′-tetrachlorobiphenyl in rats

Sulfur-containing metabolites of 2,5,2′,5′-tetrachlorobiphenyl (TCB), 4-methylthio-TCB (MT-TCB), 4-methylsulfoxyl TCB (MSX-TCB) and 4-methylsulfonyl TCB (MS-TCB) were examined for their acute toxicities, hepatic enzyme inducing activities, accumulation in the liver and lung, and excretion to the feces in rats. TCB and MT-TCB suppressed body weight and recovery of body weight gain was delayed in the MT-TCB-treated rats. MT-TCB and MS-TCB caused an increase in total liver lipid and only MT-TCB brought about an atrophy of the thymus. Treatment with MT-TCB increased cytochrome P-450 content and benzphetamine N-demethylase activity. The same enzymes were also induced by treatment with MSX-TCB. Although TCB administered was excreted mostly as hydroxylated TCB, a part was excreted as unchanged and a very small portion as the sulfur-containing metabolites. MT-TCB, MSX-TCB and MS-TCB were excreted from the MT-TCB- and MSX-TCB-treated rats. The MS-TCB-treated rats excreted only MS-TCB. The same compounds as found in the feces were identified in the liver and lung of the rats treated with those compounds except in the liver of TCB-treated rats. These results indicate that sulfur-containing metabolites, especially MT-TCB, were more important than their parent compound, TCB, from a toxicological point of view.     

Tissue retention and metabolism of 2,3,4,3′,4′-pentachlorobiphenyl in mink and mouse

2,3,4,3′,4′-Pentachlorobiphenyl was retained as the unmetabolized parent compound in liver and fat from mouse and mink. In contrast, in mouse plasma - 4-hydroxy-2,3,5,3′,4′-pentachlorobiphenyl - was present in concentrations 15 times higher than that of the parent chlorobiphenyl. In mink plasma the parent compound and the 4-hydroxylated metabolite were present in similar concentrations. Faeces was the major excretion pathway in both animals. Both the mouse and the mink excreted mainly the parent compound accompanied by trace amounts of hydroxylated metabolites but the mink also excreted significant amounts of hydrophilic metabolites, that gave hydroxylated products after acidic hydrolysis. Five hydroxylated metabolites, 4-hydroxy-2,3,5,3′,4′-pentachlorobiphenyl, 4-hydroxy-3,5,2′,3′,4′-pentachlorobiphenyl, 2-hydroxy-3,4,2′,3′,4′-pentachlorobiphenyl, 5-hydroxy-3,4,2′,3′,4′-pentachlorobiphenyl and 5-hydroxy-2,3,4,3′,4′-pentachlorobiphenyl, were identified in excreta of mink and mouse.     

The metabolism of 4,4′-dichlorobiphenyl in rats and frogs

The metabolism of 4,4′-dichlorobiphenyl in the rat has been investigated in detail and four monohydroxy-, four dihydroxy- and two trihydroxy metabolites were detected. The structures of the metabolites - except for the trihydroxy compounds - were ascertained by GC-MS studies and by comparison with synthetic compounds. Metabolism experiments in frog resulted in the isolation and characterisation of four metabolites. The structure of the major metabolites in both the rat and the frog are consistent with epoxidation of the biphenyl nucleus followed by epoxide ring opening accompanied by a 1,2-chlorine shift (NIH-shift). The formation of one minor rat metabolite, 4-chloro-3t́-biphenylol can only be explained by reductive dechlorination.     

Global baseline pollution studies XI: Congener specific determination of polychlorinated biphenyls (PCB) and occurrence of alpha- and gamma-hexachlorocyclohexane (HCH), 4,4′-DDE and 4,4′-DDT in continental air

The hexachlorocyclohexane-isomers (HCH), hexachlorobenzene (HCB), the polychlorinated biphenyls (PCB), 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (4,4′-DDT) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethene (4,4′-DDE) have been measured in urban and rural air around the city of Ulm (F. R. G., 48.4° N, 10.0° E). The sampling stations are typical for continental air in the westerlies of the northern hemisphere including local and regional influences. The analytical method consists of adsorptive sampling of large volumes (1000 m³) of air on silica gel, solvent desorption with CH₂Cl₂, preseparation of the collected chlorinated C₆/C₁₄ hydrocarbons by liquid adsorption chromatography on silica gel, and high resolution capillary gas chromatography with electron capture-(HRGC/ECD) or mass-selective detection (HRGC/MSD). The concentrations found in the lower troposphere under different meteorological conditions reflect regional input and long range transport. The levels found range from 1 pg/m³ for 4,4′-DDT to 10 ng/m³ for gamma HCH.     

Declining levels of PCB, HCB and p,p′-DDE in adipose tissue from food producing bovines and swine in Sweden 1991–2004

The official control programme for organochlorine (OC) contaminants in food producing animals in Sweden was used to study temporal and spatial trends of the polychlorinated biphenyl CB 153, hexachlorobenzene (HCB) and p,p′-DDE in adipose tissue from bovines and swine 1991–2004. Our results show that efforts to decrease OC contamination of animal feed and the environment have had a positive impact on the contamination of the animal production. OC concentrations declined significantly in almost all studied regions of Sweden. OC temporal trends were slower in bovines (6–8% per year) than in swine (10–12%). Power analyses showed that data from more than 10 years of sampling were needed for a detection of an annual OC level change of 5% in both species in the control programme, due to large within- and between-year variation in OC levels. CB 153 and p,p′-DDE levels were higher in southern than in northern Sweden. Levels decreased with age in milk cows, but not in young nulliparous cows (heifers) and bulls. Moreover, milk cows and bulls had significantly lower OC levels than heifers. Levels were not age-dependent among swine, but castrated male swine (barrows) had significantly lower OC levels than young female swine (gilts). Levels of the studied OCs are now in many cases below the LOQ of the analytical method used. Future time trend studies of these OCs thus depend on lowered LOQs in the control programme.     

Comparative toxicity of Solvent Yellow 33 [2-(2′-quinolinyl)-1,3-indandione] and Solvent Green 3 (1,4-di-p-toluidinoanthraquinone) dyes to freshwater organisms

Solvent Yellow 33 and a Solvent Green 3 mixture (30:70 mixture of Solvent Yellow 33 and Solvent Green 3) were not acutely toxic to seven of nine freshwater species when tested at the solubility limits of the dyes in freshwater. A solubility limit solution of the Solvent Green 3 mixture killed 50% of the rainbow trout tested for 96 h but was non-toxic when diluted by 50%. Both dyes caused a reduction in green algal growth at solubility limits. The Solvent Green 3 mixture was the most detrimental causing a 98–99% reduction in growth after 5 days of exposure.     

Gas-phase ozonolysis of the monoterpenoids (S)-(+)-carvone, (R)-(−)-carvone, (−)-carveol, geraniol and citral

Biogenic emissions of volatile organic compounds (VOCs) play a fundamental role in atmospheric chemistry. Vegetation is the most abundant natural source of VOCs, while terpenoids, as limonene, α and β pinene and mircene, top the plants emission list. Much interest has been demonstrated in oxidation and photooxidation reactions of VOCs, particularly of monoterpenoids, owing to their diversity and to uncertainties regarding their mechanism of reaction. Quantification of primary carbonylic compounds, as well as of biradical reaction components, is highly relevant to the understanding of the major reactions. In this context, taking into account both structural factors and the fact that these compounds are found in the essential oils of plants typically found in Brazil and that they may be present in the atmosphere from emission by the plants, the monoterpenoids (S)-(+)-carvone, (R)-(−)-carvone, (−)-carveol, geraniol and citral (a mixture of the isomers geranial and neral) were selected for this study.The ozonolysis reactions of the monoterpenoids were carried out under dark conditions for all experiments, due to their photochemical reactivity. The analysis of the results lets us propose a mechanism by which these reactions occur. The observed results of the ozonolysis of S and R carvone suggest that the stereochemistry of asymmetric carbon does not affect either in the yields of both formaldehyde and of OH radicals produced in the reaction, or in the reactivity of these compounds, for which the rate constants were in the scale of 10⁻⁶ s⁻¹.We found that, in the (−)-carveol's cis and trans mixture, even though the hydroxyl in the axial position—in the case of trans-(C) and cis-(D′) isomers—favors the attack by the ozone molecule on the external double bond, thus increasing the mixture's reactivity , it affects the average production of formaldehyde. The presence of geraniol and citral led to the production of formaldehyde, propanone, glyoxal, methyl–glyoxal and cyclohexanone (OH radicals) as reaction products. The influence of an electron attractor group bonded to the carbon of the double bond, on the reactivity of the double bond, could not be observed in the case of citral, due to strong interference occurring in the instrument in all experiments with this monoterpenoid. For this reason, only the kinetics of geraniol was monitored .     

Beyond ‘trees are good’: Disservices,management costs,and tradeoffs in urban forestry

The provision of ecosystem services is a prominent rationale for urban greening, and there is a prevailing mantra that ‘trees are good’. However, understanding how urban trees contribute to sustainability must also consider disservices. In this perspective article, we discuss recent research on ecosystem disservices of urban trees, including infrastructure conflicts, health and safety impacts, aesthetic issues, and environmentally detrimental consequences, as well as management costs related to ecological disturbances and risk management. We also discuss tradeoffs regarding species selection and local conservation concerns, as well as the central role of human perception in the interpretation of ecosystem services and disservices, particularly the uncritical assertion that ‘everybody loves trees’. Urban forestry decision-making that fails to account for disservices can have unintended negative consequences for communities. Further research is needed regarding life cycle assessments, stakeholder decision-making, return-on-investment, and framings of services and disservices in urban forestry.     

Trends in snowpack chemistry and comparison to National Atmospheric Deposition Program results for the Rocky Mountains, US, 1993–2004

Seasonal snowpack chemistry data from the Rocky Mountain region of the US was examined to identify long-term trends in concentration and chemical deposition in snow and in snow-water equivalent. For the period 1993–2004, comparisons of trends were made between 54 Rocky Mountain Snowpack sites and 16 National Atmospheric Deposition Program wetfall sites located nearby in the region. The region was divided into three subregions: Northern, Central, and Southern. A non-parametric correlation method known as the Regional Kendall Test was used. This technique collectively computed the slope, direction, and probability of trend for several sites at once in each of the Northern, Central, and Southern Rockies subregions. Seasonal Kendall tests were used to evaluate trends at individual sites.Significant trends occurred during the period in wetfall and snowpack concentrations and deposition, and in precipitation. For the comparison, trends in concentrations of ammonium, nitrate, and sulfate for the two networks were in fair agreement. In several cases, increases in ammonium and nitrate concentrations, and decreases in sulfate concentrations for both wetfall and snowpack were consistent in the three subregions. However, deposition patterns between wetfall and snowpack more often were opposite, particularly for ammonium and nitrate. Decreases in ammonium and nitrate deposition in wetfall in the central and southern rockies subregions mostly were moderately significant (p<0.11) in constrast to highly significant increases in snowpack (p<0.02). These opposite trends likely are explained by different rates of declining precipitation during the recent drought (1999–2004) and increasing concentration. Furthermore, dry deposition was an important factor in total deposition of nitrogen in the region. Sulfate deposition decreased with moderate to high significance in all three subregions in both wetfall and snowpack. Precipitation trends consistently were downward and significant for wetfall, snowpack, and snow-telemetry data for the central and southern rockies subregions (p<0.03), while no trends were noted for the Northern Rockies subregion.     

Chemical composition of rainwater in the northeastern Romania, Iasi region (2003–2006)

Chemical composition of rainwater was studied in the northeastern Romania, Iasi region, and the concentrations of major inorganic and organic ions were measured in samples collected between April 2003 and December 2006. The pH of the rainwater is 5.92 (volume weighted mean average, VWM) suggesting a sufficient load of alkaline components neutralizing its acidity. On average, 97% of the acidity in the collected samples is neutralized by CaCO₃ and NH₃. Clear seasonal variations were observed for some of the identified ions (e.g., SO₄²⁻, NO₃⁻, Ca²⁺, NH₄⁺). The data obtained during this work revealed that both concentrations and fluxes of anthropogenic source-related ions (e.g., SO₄²⁻, NO₃⁻ and NH₄⁺) are among the highest reported for European sites. It is shown that meteorology and long-range transport processes may concur to their high levels.     

Pteris vittata – Revisited: Uptake of As and its speciation, impact of P, role of phytochelatins and S

Pteris vittata is known to hyperaccumulate As but the mechanism is poorly understood. We found an increase of As concentration with increasing soil solution As concentrations, but P application had no impact, although plant P concentrations responded to different rates of P supply. As in fronds was dominantly (82–89%) present in the form of AsIII. In roots we detected 45% as AsIII which is higher than reported in previous studies and supports substantial As-reduction to take place in roots. We detected PC2/3GS–AsIII, PC2–GS–AsIII and (PC2)2–AsIII in increasing amounts with application of As. The total amount of PC was in the range reported previously and far too small to assign a significant role in As detoxification to PCs. The close correlation between S and As in fronds and the lack of data on sulphur uptake and metabolism indicates the need for a detailed investigation on sulphur nutritional status and As metabolism in P. vittata.     

The Binghamton state office building PCB, dioxin and dibenzofuran electrical transformer incident: 1981–1986

The Binghamton State Office Building (BSOB) polychlorinated biphenyl (PCB) and chlorinated benzene containing electrical transformer arcing and fire incident of February 5, 1981, was the first recognized incident of its kind. A surge of excess electricity led to an electrical panel malfunction at 5:30 AM. For about 30 minutes intense heat was generated as electrical arcing occurred. Dense smoke containing polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs) as well as biphenylenes billowed up through air shafts and contaminated all areas of the building later tested for these chemicals. This incident was the first outside a laboratory setting to demonstrate the conversion of PCBs, in the presence of oxygen and heat, to PCDFs, and of the chlorinated benzenes to PCDDs. It demonstrated a hitherto unsuspected potential health hazard of PCB and chlorinated benzene containing electrical transformers, and by implication, capacitors, when not properly separated from areas of buildings used by workers and public. The building has been shut since then and an estimated $40,000,000 may be spent on direct cleanup and rehabilitative costs prior to reopening of the building, if it is to be reopened. Elevated levels of serum PCBs were detected in workers, eg., firefighters initially involved in the fire, which stabilized at lower levels later in the year. Elevated penta- and hexa- chlorinated furan isomers corresponding to isomers found in the soot (and identical to some Yusho isomers) were found in some cleanup workers. Electron microscopy of percutaneous liver biopsies of three patients chemically exposed from the incident showed lesions similar to those seen in guinea pigs fed the soot, which was biologically quite active. This incident, and others occurring afterward, has led the US Environmental Protection Agency to ban PCB containing transformers from similar buildings.