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We investigated the daily variations in the concentration of atmospheric dioxins (PCDD/Fs and DL-PCBs) in paddy fields after the autumn harvest. The geometric mean of the concentrations of dioxins during the research period was 0.042 pg-TEQ/m3, and the concentrations ranged from 0.0058 to 0.53 pg-TEQ/m3. When the weather was calm with no rain or snow and the atmosphere was stable, relatively high concentrations of dioxins were observed. The characteristics of congeners and homologues produced through the combustion of PCDD/Fs were classified into four groups using principal component analysis and cluster analysis. In addition, agricultural chemicals (pentachlorophenol, PCP and chlornitrofen, CNP) were identified as the source of PCDD/Fs using a Bayesian semifactor model. When the dioxin concentrations were high, the combustion of TeCDFs and PeCDFs produced large emissions, representing the impact of open burning of rice straw. When the dioxin concentrations were low, the contribution of CNP was strong, indicating the effects of the release of previously used agricultural chemicals from the soil.

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (DL-PCBs) contained in the smoke generated from rice straw burning in post-harvest paddy fields in Japan were analyzed to determine their congener profiles. Both the apportionment of toxic equivalent (TEQ) by using indicative congeners and the comparison of the homolog profiles showed that the PCDDs/PCDFs/DL-PCBs present in the rice-straw smoke were greatly influenced by those present as impurities in pentachlorophenol (PCP) and chlornitrofen (CNP, 4-nitrophenyl-2,4,6-trichlorophenyl ether) formulations that had been widely used as herbicides in paddy fields in Japan. Further, in order to investigate the effects of paddy-field soil on the PCDDs/PCDFs/DL-PCBs present in rice-straw smoke, PCDD/PCDF/DL-PCB homolog profiles of rice straw, rice-straw smoke and paddy-field soil were compared. Rice-straw smoke was generated by burning rice straw on a stainless-steel tray in a laboratory. The results suggested that the herbicides-originated PCDDs/PCDFs/DL-PCBs and the atmospheric PCDDs/PCDFs/DL-PCBs contributed predominantly to the presence of PCDDs/PCDFs/DL-PCBs in the rice-straw smoke while the contribution of PCDDs/PCDFs/DL-PCBs formed during rice straw burning was relatively minimal. The major sources of the PCDDs/PCDFs/DL-PCBs found in the rice-straw smoke were attributed primarily to the paddy-field soil adhered to the rice straw surface and secondarily to the air taken by the rice straw. The principal component analysis supported these conclusions. It is concluded that rice straw burning at paddy fields acts as a driving force in the transfer of PCDDs/PCDFs/DL-PCBs from paddy-field soil to the atmosphere.

The major sources of dioxins (polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (DL-PCBs)) in the environment in Japan have been considered to be combustion by-products, pentachlorophenol (PCP) formulations, chlornitrofen (CNP, 4-nitrophenyl-2,4,6-trichlorophenyl ether) formulations, and PCB products. Data on PCDDs, PCDFs and DL-PCBs from the four sources were analyzed, and indicative congeners whose concentrations were highly correlated with WHO-2006 toxic equivalencies (TEQs) were identified for each source sample. The indicative congeners for combustion by-products, PCP formulations, and CNP formulations were 2,3,4,7,8-pentachlorodibenzofuran, 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin, and 1,2,3,7,8-pentachlorodibenzo-p-dioxin, respectively; for PCB products, the indicative congeners were IUPAC Nos. #126- and #105-pentachlorobiphenyls. Moreover, using the data on PCDDs, PCDFs and DL-PCBs, we developed a set of equations for estimating the apportionment of TEQs from the four sources by using only the concentrations of the above-mentioned five indicative congeners. The equations were used along with the analysis results of different types of environmental samples collected from Japan, to determine the TEQ contributions of the four sources. The obtained values of TEQ contributions seemed to be reasonable. The estimation method was developed by using the data on major dioxin sources in Japan, and therefore, it is generally adaptable to environmental samples from any part of Japan. The method may be usable for regions outside Japan if source identification is carried out and the estimation equations are modified appropriately.

Polyclonal and monoclonal antibodies reactive with acifluorfen (AF) were prepared by the immunization of, respectively, rabbits and mice with AF-bovine serum albumin conjugates. The reactivities of polyclonal antibody and three monoclonal antibodies (AF 9-1, AF 51-5 and AF 75-144) were examined in an indirect competitive enzyme-linked immunosorbent assay (C-ELISA). The polyclonal antibody reacted with AF at concentrations of 1.5 to 800 μg litre -1 , while the monoclonal antibodies reacted with AF at concentrations of 3 to 24 μg litre -1 for AF 9-1, 1.5 to 12 μg litre -1 for AF 51-5 and 12 to 48 μg litre -1 for AF 75-144. In the presence of up to 40% methanol in C-ELISA, the monoclonal antibodies, particularly AF 75-144, were less affected in their reactivities with AF than was the polyclonal antibody. Moreover AF 9-1 and AF 51-5 specifically reacted with acifluorfen-methyl and oxyfluorfen, while AF 75-144 reacted with chlornitrofen which did not react with the other antibodies. These results indicated that the antibodies are useful for the assay of AF and its related compounds.

有効成分として除草剤 chlornitrofen (CNP) を含有し発泡剤として炭酸水素ナトリウムおよび酒石酸を含む水田用錠剤を試作し, 温室内でその諸性質を調べた。錠剤の水中発泡速度は, 10～30℃の範囲では温度が高くなるにしたがって大きくなり, 総発泡量もこの温度範囲ではほぼ直線的に増加した。Chlornitrofen の水中溶出量は温度が高いほど多く, タイヌビエに対する除草活性も温度が高いほど強い傾向にあったが, 通常の施用量では, 10℃でも95%以上の抑草率を示した。重さ0.5gの錠剤を温度25℃, 湿度40%および90%で0～6hr保存したところ, 湿度40%では水中の総発泡量に変化はなかったが, 湿度90%では約4hrの保存で発泡しなくなった。この時も発泡性が低下するにしたがって, chlornitrofen の水中溶出量およびタイヌビエに対する殺草効果が低下した。

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs)were analyzed in preserved paddy soils periodically collected from 7 sites around Japan since 1960 to trace the changes in concentrations, to elucidate their sources, and to estimate their mass balance in Japanese paddy fields. Concentrations of sigma PCDD/Fs in paddy soils from all sites increased during the 1960s and the 1970s, then decreased. The results of principal component analysis and chemical mass balance based on functional relationship analysis indicate that the increase in sigma PCDD/F concentrations in paddy soils was due to the increased use of pentachlorophenol (PCP) and chlornitrofen (CNP); more than 95% of PCDD/Fs in all paddy soils were derived from impurities in these herbicides. The half-lives of PCDD/F for disappearance from the paddy soils were estimated to be 10 to 20 years (mean: 17.3 years). The estimated PCDD/F mass balance using the above half-life during the past 40 years in paddy fields indicates that about 80% of PCDD/Fs have disappeared. The soil puddling (mechanically mixing of paddy soil with pooled irrigation water) is implied as one reason for the PCDD/F disappearance from paddy fields. However, as the amounts of PCDD/Fs added through the use of PCP and CNP were extremely large, PCDD/F concentrations in Japanese paddy soils will decrease gradually, and PCDD/F runoff from paddy fields to surrounding catchments will continue.

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.

Dans les sols inondes, le groupe nitro du chlornitrofene est reduit de maniere non biologique par le Fe 2+ qui est produit pour une grande part par les microorganismes du sol, alors que beaucoup de microorganismes du sol pourraient reduire le groupe nitro biologiquement

Young guppies of 30 days old (Poecilia reticulata) were exposed to a formulation chlornitrofen (CNP) for 28 days. A cumulative number of fry decreased to 16 and 51% of the control in the 1st and 2nd parturition at 25 μg 1−1. Normal parturition did not occur at 125 μg 1−1. Young guppies were exposed to 200 μg 1−1 CNP for 1 to 7 days. Number of fry decreased to 50% of the control in the guppies exposed to formulation-CNP for 1 day, while the same effect was observed with 3-days exposure in the reagent grade (99%)-CNP. However, the CNP concentration of the guppy did not differ in either case. Guppies were exposed to CNP for 30 days through a CNP-accumulated tubifex. The number of fry decreased in accordance with the CNP concentrations of tubifex. At the maximum concentration (160 μg CNP g−1, wet wt.), a cumulative number of fry decreased to 23, 43 and 49% of the control in the 1st, 2nd and 3rd month, respectively. The CNP concentration of liver and female gonad was high. The retention time of CNP accumulated in female gonad was longer than that of liver.

CNPおよびそのアミノ誘導体を分解する数種の微生物を土壌から単離し, そのうち Corynebacterium sp., Streptomyces sp. および Penicillium sp. を同定した. 無機培養液中において, それら分解菌は両化合物を唯一の炭素源として利用できなかったが, 他の炭素栄養源の添加によって急速に分解した. 分解菌によるCNPの主要代謝経路は, ニトロ基の還元によるCNPアミノ誘導体の生成とそれに続くN-アセチル化, N-メチル化およびアミノ基の水酸基への置換ならびにエーテル結合の開裂であった. これら代謝経路は供試した微生物および培養液の違いにより異なった. アミノフェノールおよびホルミル体も代謝物中に検出され, フェニル基はCO2に酸化された.

Adsorption isotherms of 10 principal organochlorine pesticides on soils were investigated for predicting their fate in environment. The adsorption isotherms were expressed by Freundlich type isotherms and the adsorption constants were approximately in proportion to the organic carbon contents for the general soil samples. The adsorption constants per gram of the organic carbon in soil were in the range from 10 – 10 4 , and the values for chlornitrofen and quintozene were relatively high. The constants were correlated roughly with the octanol-water partition coefficients or solubilities in water.

The soil environment of paddy fields differs largely from that of upland fields in respects of soil properties, aquatic conditions and organisms including weeds. These factors define the properties of herbicides applied in paddy fields and largely influence the fate and behavior of the herbicides. Major pathways of disappearance of herbicides in paddy fields are photodegradation in flooding water, wolatilization and run-off from flooding water, and degradation in soil. In general, degradation in the soil, especially microbial degradation, is the major route of disappearance of many herbicides in the fields. In many cases, the degradation rates and major degradation pathways of herbicides in paddy soil differ greatly from that in upland soil. The fate of the principal paddy herbicides such as benthiocarb, molinate, chlornitrofen, chlomethoxynil, MCPA, butachlor and other herbicides in paddy soils is discussed.

Corbiculae (Corbicula japonica prime) were found to be highly polluted with a herbicide, chlornitrofen (CNP), during May and June in paddy fields in Miyagi Prefecture. Analytical procedures for residual 1, 3, 6, 8- and 1, 3, 7, 9-TCDD in corbiculae were developed and the corbiculae were also shown to be contaminated with small amounts of 1, 3, 6, 8- and 1, 3, 7, 9-tetrachlorodibenzo-p-dioxin (TCDD), which are considered to be formed as impurities during the production process of CNP.Corbiculae were analyzed at regular intervals throughout a year at a fixed monitoring point in Miyagi Prefecture. The maximum concentrations of TCDD and CNP were 39ppb and 11.2ppm, respectively, in corbiculae on May 12, 1982, and then decreased rapidly after the end of the herbicide application period. The dissipation rate of TCDD was slower than that of CNP.An analytical procedure for TCDD based on dechlorination to unsubstituted dibenzo-p-dioxin with sodium borohydride in the presence of nickel chloride was also investigated. The dechlorination procedure can be used for the screening of TCDD in relatively highly contaminated samples, and gives the value of total TCDD.

CNP (chlornitrofen), widely used as a paddy herbicide in Japan, is known to be converted readily to the corresponding amino derivative by reduction of the nitro group in the environment. An unusually high level of CNP residue concentration was reported in fresh-water fish and shellfish during the application period. Therefore, the occurrence of CNP reduction products in samples with high CNP residue levels was investigated and two unknown compounds were detected which were not identical with any standard pesticides on GLC. These two compounds, obtained in preparative scale experiments, showed high sensitivity in ECD-GC and NP-FID GC and gave CNP-amino compound on alkaline hydrolysis. From the GC-MS analysis and the above mentioned chemical property, the structures of these compounds were elucidated as CNP-acetamide (CNP-a) and CNP-formamide (CNP-f); these structures were confirmed by comparison of the products with authentic samples prepared from CNP.Analytical methods for residual CNP-a and CNP-f were established and the residual concentrations were investigated in fresh-water fish and shellfish at regular intervals through a year at a fixed location in Miyagi prefecture. The maximum concentrations of CNP derivatives were 0.58ppm (CNP-a) and 0.24ppm (CNP-f) in freshwater clam, 0.04 (CNP-a) and 0.05ppm (CNP-f) in loach, and 0.06 (CNP-a) and 0.13ppm (CNP-f) in crucian carp during May and June, and these levels decreased rapidly after the end of the herbicide application period.