Michihiko Ike

Twelve enzyme-linked immunosorbent assays (ELISA), for the determination of surfactants [linear alkylbenzene sulfonates (LAS), alkyl ethoxylates (AE), and alkylphenol ethoxylates (APE)], endocrine disruptors [alkylphenol (AP), AP + APE, and bisphenol A (BPA)], estrogens [17beta-estradiol (E2), estrone (E1), estrogen (ES: E1 + E2 + estriol (E3)), 17alfa-ethynylestradiol (EE2)], dioxins and polychlorinated biphenyls (PCBs), were validated on environmental water and industrial wastes. The lowest quantification limits of these ELISAs were 0.05 μg/L (BPA, E2, E1, ES and EE2), 2 μg/L (AE), 3 μg/L (dioxins and PCBs), 5 μg/L (AP, AP + APE) and 20 μg/L (LAS and APE). To apply these ELISAs to environmental or industrial waste samples, simple and appropriate pre-treatment methods were also developed for each ELISA. With optimized pre-treatments, the values of ELISAs were well co-related, in all cases, to those of instrumental analytical methods such as liquid chromatography (HPLC), liquid chromatography-tandem mass spectrometry (LC-MS/MS), and high-resolution gas chromatography mass spectrometry (HR-GC-MS), etc.

There is a group of compounds structurally similar to bisphenol-A (BPA), namely bisphenols (BPs), and some of them are considered to be able to partially replace BPA. In order to assess their biodegradability in the aquatic environment, a variety of BPs; BPA, bis(4-hydroxyphenyl)methane (BPF), bis(4-hydroxyphenyl)ethane (BPE), 2,2-bis(4-hydroxy-phenyl)butane (BPB), 2,2-bis(4- hydroxy-3-methylphenyl)propane (BPP), bis(4-hydroxyphenyl)sulfone (BPS), thiodiphenol (TDP) and 4,4′-dihydroxybenzophenone (HBP); were subjected to biodegradation tests under both aerobic and anaerobic conditions. For the aerobic degradation test, a kind of river-die-away method using several river water samples was used, while pond sediments were used for the anaerobic degradation tests in sealed anoxic bottles. As a whole, the examined BPs could be ranked by their biodegradability under aerobic conditions; BPF, HBP >> BPA > BPP > BPE > BPB > TDP >> BPS. On the other hand, the tendency for the anaerobic biodegradability was; BPF > HBP > BPS, BPA, TDP > BPE > BPB. From the viewpoint of biodegradability, BPF seems to be more environmentally-friendly than BPA and, therefore, may be a candidate to replace BPA for reducing the environmental risks.

Biodegradation of bisphenol‐A (BPA), which is known as an estrogenic chemical, proceeds via complicated metabolic routes and leads to formation of several kinds of biodegradation products. Through the major route BPA can be completely mineralized; however, p‐hydroxyacetophenone (p‐HAP), p‐hydroxybenzaldehyde (p‐HBAL), and p‐hydroxybenzoic acid (p‐HBA) are transiently accumulated at relatively high concentrations. On the other hand, degradation of BPA through the minor route tends to cause the accumulation of 2,3‐bis(4‐hydroxyphenyl)‐1,2‐propanediol and p‐hydroxyphenacyl alcohol as the dead‐end products. To fully assess the impact of BPA discharge into the environment, the considerable BPA degradation products p‐HAP, p‐HBAL, and p‐HBA and the mixture of the dead‐end products were examined for their acute toxicity, mutagenicity, and estrogenicity using the Daphtoxkit (Creasel Ltd.), umu test system, and yeast two‐hybrid system, respectively. BPA was moderately toxic to Daphnia magna (48‐h EC₅₀ was 10 mg/L) and weakly estrogenic, with activity that was 5 orders of magnitude lower than that of 17β‐estradiol in the yeast screen, though no mutagenicity was observed. All the tested BPA biodegradation products showed very low acute toxicity compared with BPA, and none was mutagenic. A slight estrogenic activity was detected only for p‐HAP among the tested degradation products. It was concluded that biodegradation can remarkably reduce the toxic effects of BPA. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 457–461, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10079

Behavior of nonylphenol polyethoxylates (NPnEOs, n; number of ethoxy units) in 40 full-scale sewage treatment plants (STPs) in Japan was studied. Primary effluent (PE), secondary effluent (SE) and final effluent (FE) samples were collected from the STPs, and NPnEOs, their metabolic intermediates and related halogenated derivatives were quantitatively analyzed. Parent NPnEOs (n=4–18) were detected at concentrations between 5.1 and 1035 μg/l with the average value of 296 μg/l in the PEs from all the STPs, indicating widespread pollution of NPnEOs in Japan. The analyses of SEs revealed that normal biological treatment can relatively efficiently remove NPnEOs, however, the biotransformation led to the formation of biologically-refractory metabolites like nonylphenol (NP), NPnEOs with shorter ethoxy chains (n=1–3; NP1-3EO) and nonylphenol carboxylic acids (NP1-3EC). Halogenated (chlorinated or brominated) NPnEOs and/or NPnECs (n=1–2), which are considered to be produced as by-products during the disinfection processes using chlorination, were also found in SEs and/or FEs from 25 STPs. The ecotoxicity assays showed that the metabolic intermediates of NPnEOs possess higher acute toxicity against Daphnia magna and estrogenic activity than the parent surfactant NPnEOs.

An enrichment culture taken from a contaminated site could efficiently degrade tetrachloroethylene (PCE) under a sequential anaerobic/aerobic condition. Under an anaerobic condition using citrate as a carbon source and yeast extract as a nutritional requirement, the enrichment culture could transfer 60 μM of PCE nearly stoichiometrically to cis-1, 2-dichloroethylene (cis-DCE) via trichloroethylene (TCE) within 3 days. A solution of 19.6% H₂O₂ was added atfinal concentration of 1.0% (v/v) to change the anaerobic condition of medium to aerobic one. Under the aerobic condition, more than 80% of cis-DCE accumulated was co-metabolized by indigenous phenol degrading bacteria in the enrichment culture. During the co-oxidation in the aerobic condition, all of phenol (125 mg/liter) added were completely consumed and population of phenol degrading bacteria was increased. The degradation of cis-DCE was affected by H₂O₂ (0.1-2.0% (v/v) ) and phenol (0-250 mg/liter) concentrations, indicating that the optimum doses of H₂O₂ and phenol are very important to lead successful co-metabolisms of less chlorinated ethylenes under aerobic conditions. The results from this research suggested that the sequential anaerobic/aerobic biostimulation would be viable as a cost-effective and safe bioremediation technique for degradation of PCE and less chlorinated metabolites. But it should need thorough investigation of microbial populations and their interactions for degrading chlorinated ethylenes under anaerobic and aerobic environments of contaminated sites.

The metabolic pathway of the phenol degradation in Pseudomonas putida BH was amplified by introducing the recombinant plasmid containing catechol 2,3 oxygenase gene isolated fron the chromosome of BH. This strain could degrade phenol and grow much faster than the wild strain at the phenol concentration of 100mg/L. This strain seems to accelerate the phenol removal rate if it is applied to the treatment of wastewater containing phenol.