Exposure to polybrominated diphenyl ethers and tetrabromobisphenol A among computer technicians

This study investigates exposure to polybrominated diphenyl ethers (PBDEs) and tetrabromobisphenol A (TBBPA), which are used as flame retardants in electronic equipment, in a group of technicians with intense computer work. Thirteen PBDE congeners and TBBPA were quantified in serum from 19 computer technicians. Previously investigated groups of hospital cleaners with no computer experience, and clerks working full-time at computer screens were used for comparison. The computer technicians had serum concentrations of BDE-153, BDE-183 and BDE-209 that were five times higher than those reported among hospital cleaners and computer clerks. The median levels observed among the computer technicians were 4.1, 1.3, and 1.6 pmol/g lipid weight, respectively. In contrast, for BDE-47 there was no difference between the computer technicians and the others. BDE-100, BDE-203, and three structurally unidentified octa-BDEs and three nona-BDEs, were present in almost all samples from the computer technicians. Further, TBBPA was detected in 8 out of 10 samples. The levels of BDE-153, BDE-183, and one of the octa-BDEs were positively correlated with duration of computer work among technicians. On a group level an exposure gradient was observed, from the least exposed cleaners to the clerks, and to the highest exposed group of computer technicians. A dose (duration of computer work)-response relationship among computer technicians was demonstrated for some higher brominated PBDE congeners. Thus, it is evident that PBDEs used in computers and electronics, including the fully brominated BDE-209, contaminate the work environment and accumulate in the workers tissues.     

Role of loosely bound humic substances and humin in the bioavailability of phenanthrene aged in soil

A study was conducted to determine a possible role of loosely bound humic substances (i.e., humic and fulvic acids) in bioavailability of aged phenanthrene with time. In this study, long-term residence of phenanthrene in soil is defined as aging or sequestration, and the effect was determined by the declined bioavailability to bacteria of the polycyclic aromatic hydrocarbon with increased residence time. After 1, 7, and 100 days of aging of phenanthrene in Lima loam, about 90-93% of initial phenanthrene was recovered from the humin-mineral fraction of Lima loam whereas less than 12% was found in humic and fulvic acids of the same soil. Mineralization rates of phenanthrene aged in the humin-mineral fraction significantly decreased with time by the test bacterium P5-2. In terms of extents of mineralization, the difference with time was not appreciable, but still significant at P<0.05. Additional decreases in the rates and extents of mineralization were observed with the whole soil (i.e. Lima loam) to which phenanthrene had been aged. Data suggest that major sequestration sites for phenanthrene may reside in the humin-mineral fraction, and probably humic and fulvic acids may act as a physico-chemical barrier to bacterial degradation so that the compound's bioavailability may be limited.     

Development of ELISA technique for the analysis of atrazine residues in water

A highly sensitive enzyme immunoassay is described for the detection of atrazine residues in water. Atrazine derivative was conjugated to Bovine Serum Albumin (BSA) to obtain an immunizing antigen and to Horseradish Peroxidase enzyme (POD) to obtain a marker for immunoassay. The formation of these conjugations was confirmed by UV spectroscopy as well as by gel-electrophoresis. Polyclonal antibodies were raised in rabbits by immunization with an atrazine-BSA conjugate containing 29 atrazine residues per BSA molecule. An ELISA on microtitration plates was optimized with peroxidase-atrazine conjugate. The middle of the test (50% B/Bo) was found to be at 90 ng/l, which is well below the maximum concentration permitted by the EC guidelines for drinking water. Detection limits for atrazine of about 1 ng/l could be reached. The assay did not require concentration or cleanup steps for drinking or ground water samples. Validation experiments showed good accuracy and precision. No cross-reactivities were shown by other s-triazines like terbutryn, ametryn, terbuthylazine, des-isopropylatrazine, and de-ethylatrazine except hydroxyatrazine. The latter was present at very low levels that can be calibrated/standardized before analysis or it may be considered as leftover residues of atrazine. Based on these results, it is suggested that this test can be applied to obtain fairly accurate results for atrazine concentration in water samples from different sources.     

Peroxidative degradation of selected PCB: a mechanistic study

The enzyme-induced decomposition and biodegradation of PCB were investigated. 2,5-Dichlorobiphenyl (PCB 9) and 2,2^′,5,5^′-tetrachlorobiphenyl (PCB 52) were used as example compounds to study efficiency and mechanism of the degradation processes. It was found that the application of horseradish peroxidase (HRP) together with defined amounts of hydrogen peroxide removed 90% of the initial concentration of PCB 9 and 55% of the initial concentration of PCB 52 from an aqueous solution after a reaction period of 220 min. Dechlorination was observed as the initial step. Although the metabolites identified were mainly chlorinated hydroxybiphenyls, benzoic acids and non-substituted 1,1^′-biphenyl, some higher chlorinated biphenyl isomers also appeared. The biodegradation of PCB 9 using the white rot fungus Trametes multicolor took about four weeks and reduction was about 80% of the initial concentration. The metabolites produced (dichlorobenzenes, chlorophenols and alkylated benzenes) were not quite the same as those observed upon incubation with HRP.     

Long-range air pollution and its impact on heavy metal accumulation in dippers Cinclus cinclus in Norway

Heavy metals such as cadmium, lead and zinc are deposited in Norway as long-range transported air pollution, while copper deposition is of mainly local origin. This study examined whether the deposition influences the metal concentrations in dippers Cinclus cinclus. The lead concentration in dippers reflected the deposition pattern of long-range air pollution, with higher concentrations in Southern Norway than Central Norway and a significant decrease (>/=40%) between 1987 and 1994. For cadmium, copper and zinc there were no geographical or temporal variations in metal concentrations. For zinc, this lack of geographic and temporal variation probably reflects the fact that it is a homeostatically regulated metal. For both cadmium and copper, local sources are probably more important than long-range sources. Zinc and copper was at higher level in livers of females than in males during the egg laying period. The concentrations of zinc and copper in livers were positively correlated.     

Response of a grassland ecosystem to air pollutants: II--The chemical climate: Fluxes of sedimenting airborne matter

Measurement of the deposition of sedimenting particles requires a sampling device, which avoids simultaneous deposition of gases and aerosols to the collection surface. A sampler constructed for the purpose of collecting rain and sedimenting particles is described and characterized in detail, in particular with regard to its collection efficiency for rain. Its collection properties for gases and aerosols are shown to be negligible. From two years of sampling at different heights it was found that resuspension of particles and co-condensation of gases near the plant canopy may lead to a major overestimation of bulk deposition. As a consequence, the extension towards the canopy of the constant flux layer for sedimenting particles has to be determined experimentally. Bulk deposition of sodium, potassium, magnesium, calcium, lead, copper, cadmium, manganese, iron, ammonium, nitrate, phosphate, sulfate, total sulfur and chloride at Braunschweig-V?lkenrode, Southeast Lower Saxony, Germany, were recorded for six years. During this period a considerable decrease was observed in the deposition of lead, cadmium, nitrate, sulfate and total sulfur.     

Chlorpyrifos degradation in Turkish soil

Degradation of chlorpyrifos was evaluated in laboratory studies. Surface (0-15 cm) and subsurface (40-60 cm) clay loam soils from a pesticide-untreated field were incubated in biometer flasks for 97 days at 25 degrees C. The treatment was 2 micrograms g-1 [2,6-pyridinyl-14C] chlorpyrifos, with 74 kBq radioactivity per 100 g soil flask. Evolved 14CO2 was monitored in KOH traps throughout the experiment. Periodically, soil subsamples were also methanol-extracted [ambient shaking, then supercritical fluid extraction (SFE)], then analyzed by thin-layer chromatography. Total 14C and unextractable soil-bound 14C residues were determined by combustion. From the surface and subsurface soils, 41 and 43% of the applied radiocarbon was evolved as 14CO2 during 3 months incubation. The time required for 50% loss of the parent insecticide in surface and subsurface soils was about 10 days. By 97 days, chlorpyrifos residues and their relative concentration (in surface/subsurface) as % of applied 14C were: 14CO2 (40.6/42.6), chlorpyrifos (13.1/12.4), soil-bound residues (11.7/11.4), and 3,5,6-trichloropyridinol (TCP) (3.8/4.8). Chlorpyrifos was largely extracted by simple shaking with methanol, whereas TCP was mainly removed only by SFE. The short persistence of chlorpyrifos probably relates to the high soil pH (7.9-8.1).     

Contribution of vehicle emissions from an attached garage to residential indoor air pollution levels

The infiltration of vehicle emissions into a house from the attached garage was studied for 16 homes of differing designs using the same extensively characterized vehicle at each home. Before the in-home measurement program, the cold-start and hot-start tailpipe emissions and hot-soak evaporative emissions from a 1993 Buick Regal were measured using standard vehicle emissions measurement methods. The emissions were chemically characterized for methane, nonmethane hydrocarbons (NMHC), and carbonyl compounds. The in-home measurements occurred over two winter seasons (1997-1998 and 1998-1999) in Ottawa, Ontario, Canada. Samples of indoor air and garage atmosphere were characterized for carbon monoxide, carbon dioxide, methane, NMHC, and carbonyl compounds. During the second year, real-time measurements of carbon, carbon dioxide, and total hydrocarbons were made to determine when and for how long the emissions plume infiltrates the house. Chemical mass balance modeling results using 31 NMHC species suggest that between 9 and 71% of the concentrations measured in the house during the hot-soak test and between 13 and 85% of the concentrations measured in the house during the cold-start test could be attributed to vehicle emissions infiltrating from the garage. In contrast, increases in carbonyl compound concentrations caused by the vehicle were difficult to detect above the already significant levels found in the houses.     

Tissue distribution and effects on hepatic xenobiotic metabolising enzymes of 2,3,3',4,4'-pentachlorobiphenyl (PCB-105) in COD (Gadus morhua) and rainbow trout (Oncorhynchus mykiss)

2,3,3',4,4'-Pentachlorobiphenyl, PCB-105 (IUPAC no. 105) was orally administered twice with a 4-day interval between dosings (total dose 10 mg kg(-1) body weight) to gonadally immature cod and rainbow trout of both sexes. The fish were killed 9 and 17 days after the first treatment, and the effects of PCB-105 on hepatic xenobiotic metabolising enzymes were determined by examining the cytochrome-P450-dependent ethoxyresorufin-O-deethylase (EROD) and aldrin epoxidase activities, and the EROD-catalysing P450 1A1 protein by indirect enzyme-linked immunosorbent assay (ELISA). Glutathione S-transferase activity towards 1-chloro-2,4-dinitrobenzene was included. The hepatic levels of the compound were determined. In addition, the distribution patterns of radio-labelled PCB-105 were studied by whole-body autoradiography. In exposed rainbow trout EROD activity and P450 1A1 by enzyme linked immunosorbent assay (ELISA) were significant induced, while GST activity was significant reduced. Exposed cod did not show significantly different enzyme values from controls, but percentage fat in the liver was significantly reduced. The whole cod liver contained about 1000 times more PCB-105 than the corresponding trout liver, and on a fat-weight basis the PCB level was five to six times higher in cod liver than in the rainbow trout liver. The autoradiographical investigation revealed high concentrations of radiolabelled compound in the liver and the brain of cod, while in rainbow trout the radiolabel was mainly confined to extrahepatic fat depots. These results demonstrate that the mono-ortho chlorinated coplanar analogue, PCB-105, has a different distribution pattern in the two fish species and that the potential for induction of the hepatic xenobiotic metabolising enzyme system seems to be lower in the cod than in the rainbow trout.     

Fate and mobility of pharmaceuticals in solid matrices

The sorption and mobility of six pharmaceuticals were investigated in two soil types with different organic carbon and clay content, and in bacterial biomass (aerobic and anaerobic). The pharmaceuticals examined were carbamazepine, propranolol, diclofenac sodium, clofibric acid, sulfamethoxazole and ofloxacin. The sorption experiments were performed according to the OECD test Guideline 106. The distribution coefficients determined by this batch equilibrium method varied with the pharmaceutical tested and the solid matrix type. Ofloxacin was particularly strongly adsorbed (except of the case of using anaerobic biomass for the solid matrix) while clofibric acid was found to be weakly adsorbed. The fate of pharmaceuticals in soil was also assessed using lysimeters. Important parameters that were studied were: the pharmaceutical loading rate and the hydraulic loading rate for adsorption and the rate and duration of a "rain" event for desorption. Major differences in the mobility of the six pharmaceuticals were observed and correlated with the adsorption/desorption properties of the compounds.