Assessment of thyroid hormone activity of halogenated bisphenol A using a yeast two-hybrid assay

The thyroid hormone agonist/antagonist activities of halogenated derivatives of bisphenol A (BPA) were assessed using a yeast two-hybrid assay incorporating the human thyroid hormone α (TRα), both with and without possible metabolic activation by rat liver S9 preparation. In the absence of the rat liver S9 preparation, 3,3′,5,5′-tetrabromobisphenol A (TBBPA), 3,3′,5,5′-tetrachlorobisphenol A (TCBPA), and 3,3′,5-trichlorobisphenol A (3,3′,5-triClBPA) exhibited agonist activity, whereas 3-chlorobisphenol A (3-ClBPA), 3,5-dichlorobisphenol A (3,5-diClBPA), 3,3′-dichlorobisphenol A (3,3′-diClBPA), and BPA did not. The activities of TBBPA and TCBPA increased markedly (7.6-fold and 3.1-fold, respectively) after their metabolic activation with the rat liver S9 preparation. TBBPA, TCBPA, and 3,3′,5-triClBPA inhibited the binding of triiodothyronine (T3) to TRα at 2 × 10⁻⁵ M without rat liver S9 treatment and 4 × 10⁻⁶ M with rat liver S9 treatment, demonstrating their T3 antagonist activity. These results revealed that metabolic activation by rat liver S9 significantly increased the agonist/antagonist potential of some halogenated BPAs.     

Effects of wavelength and water quality on photodegradation of N-Nitrosodimethylamine (NDMA)

N-Nitrosodimethylamine (NDMA) is a potent carcinogen that yields a cancer risk of 10⁻⁶ at concentrations as low as 0.7 ng L⁻¹. Tentative guideline values are set at 3 ng L⁻¹ in California, USA; 9 ng L⁻¹ in Ontario, Canada; 40 ng L⁻¹ nationwide in Canada; and 100 ng L⁻¹ by the World Health Organization. NDMA is a great concern in treating reclaimed water as well as drinking water. UV degradation can be considered effective degradation method. A 1-log reduction of NDMA is achieved by 1000 mJ cm⁻² of a 254-nm low pressure (LP) mercury UV lamp. However, a higher degradation efficiency than that provided by LP lamps is desired in practical treatment. In this study, the effects of wavelength and water quality were investigated to achieve higher degradation efficiency. The effects of wavelength were examined by comparing three UV lamps: a 222-nm Kr Cl Excimer UV lamp, a 254-nm LP mercury UV lamp, and a 230- to 270-nm filtered medium pressure (FMP) mercury UV lamp. The 222-nm lamp and FMP lamp achieved 4 times and 2.8 times higher degradation efficiency, respectively, than the conventional 254-nm LP lamp. Effects on water quality were also simulated by using absorption spectrum data of nitrate solutions and process water from a drinking-water treatment plant. In the simulation, the 222-nm lamp was affected by UV-absorbing compounds in the water, whereas the FMP lamp showed more stable degradation efficiency. Appropriate use of these three types of lamps could enhance the efficiency of degradation of NDMA.     

Current levels of airborne polyfluorinated telomers in Japan

Fluorotelomer alcohols (FTOHs), a class of per- and poly-fluorochemicals (PFCs), are environmental contaminants characterized by high volatility and are therefore prone to long-range atmospheric transport. In this study, airborne FTOHs were identified in Japan using a newly developed passive air sampler containing activated carbon felts. Air sampling was conducted at 33 sites all over Japan from April to June 2007. 8:2 FTOH, the dominant analyte, ranged from <32 to 2466pgm(-3) (mean: 241pgm(-3)) followed by 6:2 FTOH from n.d. to 768pgm(-3) (mean: 51.6pgm(-3)), 10:2 FTOH from <17 to 113pgm(-3) (mean: 26.8pgm(-3)) and 8:2 FTOAcryl from n.d. to 480pgm(-3) (mean: 25.8pgm(-3)). 8:2 FTOMethacryl was not detected above detection limit (3pgm(-3)) in all samples. The highest concentration of total investigated PFCs was found in Chiba (35 degrees 43'20' N 140 degrees 39'46' E) (2152-3181pgm(-3)). On the other hand, in three locations of Higashi-Yodogawa (34 degrees 44' N 135 degrees 32' E), high levels of 8:2 FTOAcryl (239pgm(-3), 109-480pgm(-3)) were detected, the levels of which were comparable to those of 8:2 FTOH (mean: 175pgm(-3), range: 115-292pgm(-3)). This study is the first national wide-scale survey of FTOHs and 8:2 FTOAcryl across Japan, showing that 8:2 FTOH was ubiquitous in the environment in Japan.     

Contribution of metabolites to mutagenicity during anaerobic biodegradation of fenitrothion

The contribution of fenitrothion and its microbial metabolites to the mutagenicity of a fenitrothion-containing solution was investigated during anaerobic biodegradation. Although a mixed culture of bacteria obtained from a paddy field degraded fenitrothion and reduced its concentration from 4.6 to 0.1 mg/l in 6 days, the indirect mutagenicity of the solution in Salmonella strain YG1029 increased. This increase was found to be partially due to amino-fenitrothion generated during the biodegradation. In addition, other unidentified metabolites contributed to the mutagenicity. In contrast, the indirect mutagenicity in strain YG1042, which was initially large because of fenitrothion, then decreased, and increased again. This increase in mutagenicity was also due to amino-fenitrothion and other unidentified metabolites. The mutagenicity in strains YG1029 and YG1042 decreased after day 6. The greatest contribution of amino-fenitrothion to the mutagenicity was calculated to be 73% and 61% in YG1029 and YG1042 on day 3 of incubation, respectively. That of unidentified metabolites was calculated at 49% and 61% on day 20, respectively. Therefore, because not all the toxic metabolites of a compound can be identified, it is important to evaluate the toxicity of a whole solution in a bioassay such as the Ames assay rather than deducing the toxicity of the solution from the combined toxicities of known metabolites.     

Studies on automated survey system of environmental chemicals by gas chromatography-mass spectrometry-computer I. Retrieval system of mass spectra

A retrieval system of mass spectra based upon the Probability Based Matching method was studied in order to apply it to survey the chemicals in environments by a gas chromatography-mass spectrometry-computer system. As retrieval indices, peak missing probability and relative confidence value were proposed.     

Fate of mutagenicity produced during anaerobic biodegradation of the herbicide chlornitrofen (CNP)

The mutagenicity of chlornitrofen (CNP)-containing solutions has been reported to increase during anaerobic biodegradation. In the present study, the fate of this increased mutagenicity under subsequent aerobic and anaerobic incubation conditions was investigated using two Salmonella tester strains, YG 1024 (a frameshift-detecting strain) and YG 1029 (a base-pair-substitution-detecting strain). Mutagenicity for both YG 1024 and YG 1029 strains increased during nine-day anaerobic biodegradation. During subsequent anaerobic incubation, the increased mutagenicity decreased gradually for YG 1029 but did not change significantly for YG 1024. By contrast, the increased mutagenicity decreased rapidly after the conversion to aerobic incubation for both YG 1024 and YG 1029 strains. The rapid decrease in mutagenicity during aerobic incubation was due to decreases, not only in an identified mutagenic metabolite (CNP-amino) but also in unidentified mutagenic metabolites.     

Antimony in municipal waste.

Antimony content in municipal waste was studied. Sampled municipal waste was dried, crushed and analyzed. Antimony determinations were performed by Kjeldahl decomposition--batch hydride generation spectrometry and neutron activation analysis. Overall content of antimony in waste was 40-50 g/t raw waste. It was estimated than 20% of the annual production of antimony was discarded as municipal waste in Japan. Leaching of antimony from antimony-added materials may occur, because "small tips" involved considerable amounts of antimony.     

Changing seasonality in Bangladesh

Regional Environmental Change - Bangladesh is reported to suffer from climatic changes, and local people begin to wonder that six seasons in Bangladeshi annual calendar transition to four seasons....     

Sorption-desorption of atrazine and diuron in soils from southern Brazil

The objective of this study was to investigate the behavior of sorption and desorption of the herbicides atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) and diuron [3-(3,4-dichlorophenyl)-1,1-dimethyleurea] in soil samples from a typical lithosequence located in the municipality of Mamborê (PR), southern Brazil. Five concentrations of 14C-atrazine and 14C-diuron were used for both herbicides (0.48, 0.96, 1.92, 3.84, and 7.69 mg L(-1)). Sorption of both herbicides correlated positively with the organic carbon and clay content of the soil samples. Sorption isotherms were well described by the Freundlich model. The slope values of the isotherm (N) ranged from 0.84 to 0.90 (atrazine) and from 0.75 to 0.79 (diuron) for the lithosequence samples. Sorption of diuron was high regardless of the soil texture or the concentration added. The desorption isotherms for atrazine and diuron showed good fit to the Freundlich equation (R2 >or= 0,87). Atrazine slope values for the desorption isotherms were similar for the different concentrations and were much lower than those observed for the sorption isotherms. Significant hysteresis was observed in the herbicide desorption. When the two herbicides were compared, it was found that diuron (N = 0.06-0.22) presented more pronounced hysteresis than atrazine. The results showed that, quantitatively, a greater atrazine fraction applied to these soils remains available to be leached in the soil profile, as compared to diuron.