[Fate of Organophosphorus Flame Retardants in Polished Rice during the Cooking Process].

The fate of organophosphorus flame retardants (PFRs) in polished rice during the cooking process was examined. After adding PFRs to polished rice (500 ng/g), the rice was washed with water and cooked in a rice cooker. Among the seven kinds of PFRs, approximately 68-86% of the PFRs residues were removed after washing with water three times. In the first washing with water, approximately 50-70% of the PFRs residues were removed from rice. By the subsequent heating in an electric rice cooker or in a microwave rice cooker, the removal rates of PFRs in the cooked rice were 74-94 and 78-96%, respectively. The removal rates in musenmai (500 ng/g) which need not to wash before cooking were lower than those in the washed rice. In the cooked musenmai, 10-50% of the PFRs residues were removed after heating in the electric rice cooker, and 10-70% were removed in the microwave rice cooker. The washing process is effective to reduce the intake of PFRs from rice.

[Adsorption of Airbone Organophosphorus Flame Retardants on Polished Rice Stored in a House].

In order to clarify the actual situation of indoor pollution to polished rice with organophosphorus flame retardants (PFRs) which are ubiquitous in the indoor environment, the pollution of PFRs to polished rice stored in a house for a week was investigated. The survey covered 64 ordinary families in the Osaka region. We analyzed six typical PFRs in 37 rice samples in 2015, and ten typical PFRs in 27 rice samples in 2016. Polished rice was homogenized with acetone-hexane and defatted by hexane-acetonitrile partition. Quantitative analysis for PFRs was performed by GC-FPD. The detection frequency of PFRs in the rice samples was 35/37 in 2015 and 27/27 in 2016. The highest values were 160 ng/g for TCEP, 500 ng/g for TCIPP and 430 ng/g for TBEP. The concentration ratio of each detected PFR in the polished rice samples was different in each house. In the analysis of 16 polished rice samples which were stored in the home, PFRs were detected in ten samples regardless of the storage methods. PFRs were detected from 12 out of 16 commercial brown rice samples. This result suggested that they were polluted during distribution and storage process of them.

[Chlorpyrifos-Methyl, Pirimiphos-Methyl and Fenitrothion Residues in Commercial Wheat Products].

We measured the concentrations of organophosphorus pesticide （chlorpyrifos-methyl, pirimiphos-methyl and fenitrothion） residues in domestic and imported commercial wheat products （flour, noodles, cookies） collected from 2008 to 2016. Chlorpyrifos-methyl and fenitrothion in domestic flour samples were detected in 16 out of 34 samples at levels of ＜0.001 to 0.016 ppm, and in 14 out of 34 samples at levels of ＜0.001 to 0.004 ppm. Chlorpyrifos-methyl was detected in 22 out of 38 domestic cookies at levels of ＜0.001 to 0.054 ppm （median: 0.001 ppm）. Relatively high concentrations of chlorpyrifos-methyl （0.005 to 0.054 ppm） were found in six domestic cookies containing wheat bran. Pirimiphos-methyl was detected in 32 out of 68 cookies from foreign countries at levels of ＜0.001 to 0.11 ppm. Pirimiphos-methyl was detected frequently in products imported from Europe.

[Determination of S-421 in Commercial Fish and Shellfish].

S-421 is a synergist of pyrethroid and organophosphorus pesticides, which are used as termiticides or household insecticides. S-421 is stable and ubiquitous in the environment. Here we describe the concentrations of S-421 in domestic and imported commercial fish collected from 2009 to 2016. Samples were extracted with acetone/hexane and S-421 was purified on a silica gel column. Quantitative analysis was performed by GC-ECD. S-421 was detected in 78 of 116 samples of domestic fish and shellfish at levels of <0.2 to 2.6 ng/g (mean: 0.4 ng/g), and in 69 of 102 imported samples at a level of <0.2 to 1.5 ng/g (mean: 0.4 ng/g). The concentrations of S-421 in fish were lower than those of p,p'-DDE and similar to those of ß-HCH.

[Toxicity and toxin profile of the dinoflagellate Alexandrium tamiyavanichii and toxic mussels in Harima-Nada of Seto Inland Sea, Japan].

From October to November 2004, the paralytic shellfish poison (PSP)-producing dinoflagellate Alexandrium tamiyavanichii was observed at Harima-Nada, Seto Inland Sea at a maximum cell density of 4,960 cells/L. The wild cells of the dinoflagellate collected from the same seawaters, and cultured cells derived from them showed toxicity scores of 6.25-15.4 x 10(-4) and 2.7-3.5 x 10(-4) MU/cell, respectively, both of which were much higher than those of previously reported strains. PSP of the wild cells was mainly composed of gonyautoxin (GTX) 5 (40.6-52.4 mol%) and GTX4 (15.6-24.8 mol%), showing a unique composition that was greatly different from those of the previously reported strains, or of the cultured cells, whose main toxin component was GTX3 (average 37.6 mol%). The mussel Mytilus galloprovincialis collected from the same area in the same period accumulated a relatively high level of PSP (13-28 MU/g), suggesting a risk that A. tamiyavanichii may induce high-level PSP contamination of bivalves even at a cell density as low as around 5,000 cells/L.

A new analytical method for gonyautoxins based on postcolumn HPLC.

A new ion-pairing high-performance liquid chromatography (HPLC) method on a C30 column with a volatile mobile phase was developed to separate the gonyautoxin group (GTXs) from contaminants, allowing the utilization of liquid chromatography/mass spectrometry (LC/MS) with higher performance. A mobile phase consisting of 5 mmol/L heptafluorobutyric acid and 2% acetonitrile in 10 mmol/L ammonium acetate was adopted for separation of GTXs because the C30 column strongly retains GTXs under acidic conditions. The newly adopted method could efficiently separate GTXs from contaminants, especially in the toxic short-necked clam, whereas the routine HPLC so far used has poor resolution to separate GTXs from unknown interfering substances. In our method, GTXs were eluted in the order of GTX5, GTX3, GTX4, GTX2 and GTX1 from the C30 column, and were successfully determined by sonic spray ionization mass spectrometry (SSI-MS) with high sensitivity. This method is characterized by the combination of HPLC using a fluorescence detection system for PSP, and SSI-MS for measurement of the mass number.

First paralytic shellfish poison (PSP) infestation of bivalves due to toxic dinoflagellate Alexandrium tamiyavanichii, in the southeast coasts of the Seto Inland Sea, Japan.

The mussel Mytilus edulis and the cultured ark shell Anadara broughtonii in the southeast coasts of the Seto Inland Sea were contaminated with paralytic shellfish poison (PSP) following the appearance of the dinoflagellate Alexandrium tamiyavanichii in early December 1999. A. tamiyavanichii plankton collected around the Straits of Naruto on December 3, 1999 showed PSP toxicity, of which 83 mol% was accounted for by GTX2, GTX3 and GTX4. Its specific toxicity was 112.5 fmol/cell, and one MU was equivalent to 7,200 cells. Toxicity values at the beginning of toxification were 4.7 MU/g for the ark shell and 7.3 MU/g for the mussel. In the former, the value remained at almost 4 MU/g, resulting in prohibition of marketing for about two months. In the latter, it sharply decreased to less than 4 MU/g. These bivalves collected during the toxification period were dissected into five tissues, mantle, adductor muscle, hepatopancreas, gills and "others", and submitted to high-performance liquid chromatography (HPLC). The cultured ark shell accumulated GTX2, GTX3 and STX as major components and GTX1, GTX4, GTX5, neoSTX, dcSTX and PX1-3 (C1-C3) as minor ones. The amount of GTX3 decreased with time, while STX tended to increase. At the early stage of PSP toxification, toxins were accumulated in the gills and "others", most of which were quickly detoxified. On the other hand, PSP of the toxified mussel consisted of GTX4 as a main component, and GTX1, GTX2, GTX3, GTX5, STX and PX1-2 (C1-C2) as minor ones. Its toxin composition pattern was similar to that of the ingested causative plankton. Its total toxin decreased soon after disappearance of the dinoflagellate. During the decrease of toxicity, PSP tended to be retained in the hepatopancreas, resulting in accumulation of 50 mol% of total toxin.