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Exposure to per- and polyfluoroalkyl substances (PFAS) is of great concern for human health because of their persistence and potentially adverse effects. Dietary intake, particularly through aquatic products, is a significant route of human exposure to PFAS. We analyzed perfluoroalkyl sulfonic acid (PFSA with carbon numbers from 6 to 8 and 10 (C ６ -C 8 , C 10 )) and perfluorooctanesulfonamide (FOSA), and perfluoroalkyl carboxylic acid (PFCA with carbon numbers from 6 to 15 (C 6 -C 15 )) in 30 retail packs of edible shrimps, which included seven species from eight coastal areas of Japan and neighboring countries. The most prevalent compounds were perfluorooctane sulfonate (PFOS, C 8 ) and perfluoroundecanoic acid (PFUnDA, C 11 ), accounting for 46 % of total PFAS. The concentrations ranged from 6.5 to 44 ng/g dry weight (dw) (equivalent to 1.5 to 10 ng/g wet weight (ww)) and varied according to species and location. For example, Alaskan pink shrimp (Pandalus eous) from the Hokuriku coast, Japan contained high levels of long-chain PFCAs (38 ng/g dw (equivalent to 8.7 ng/g ww)), while red rice prawn (Metapenaeopsis barbata) from Yamaguchi, Japan contained a high concentration of PFOS (29 ng/g dw (equivalent to 6.7 ng/g ww)). We also observed regional differences in the PFAS levels with higher concentrations of long-chain PFCAs in Japanese coastal waters than in the South China Sea. The PFAS profiles in shrimp were consistent with those in the diet and serum of Japanese consumers, suggesting that consumption of seafood such as shrimp may be an important source of exposure. The estimated daily intake of sum of all PFAS from shrimp from Japanese coastal water was 0.43 ng/kg body weight/day in average, which could reach the weekly tolerable values (4.4 ng/kg body weight /week) for the sum of the four PFSA set by the EFSA for heavy consumers. The high concentration of PFAS in shrimp warrants further investigation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

The scallop, Patinopecten yessoensis, was screened for new saxitoxin analogues to study the metabolism of paralytic shellfish toxins (PSTs), and this resulted in the discovery of two new analogues: M5-hemiaminal (HA) and M6-HA. M5-HA was isolated and its structure was determined by using NMR spectroscopy. It contains hydrogen at C-4 with opposite stereochemistry to that in saxitoxin, and a hemiaminal was formed between 9-NH 2 and the hydrated ketone at C-12 in α-orientation. This is the first reported structural feature in a natural saxitoxin analogue, whereas the same ring system has previously been reported in a synthetic saxitoxin analogue, FD-saxitoxin. Acid hydrolysis of the carbamoyl N-sulfate in M5-HA produced M6-HA which was also identified in P. yessoensis by using LC-MSMS. M5-HA was not synthetically produced from M1 (11-hydroxy gonyautoxin-5) and M3 (11,11-dihydroxy gonyautoxin-5) through incubation in aqueous buffers. Furthermore, PSTs in the hepatopancreas of P. yessoensis, cultured in a bay located in northeastern Japan, were chronologically analyzed in 2018. The highest concentrations of M1/M3/M5-HA were observed two weeks after C-toxins had reached their highest concentrations, which provides evidence that M1/M3/M5-HA are metabolites of C-toxins. The voltage-gated sodium channel blockage activity of M6-HA was not detected at the concentration of 140 nM by using the Neuro-2A veratridine/ouabain assay., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The worldwide microplastic pollution in our environment is a matter of great concern. Harmful effects of plastics have been reported in various types of organisms including murine animals. We examined the presence of microplastics in four types of shellfish purchased from fish markets in Okayama, Japan and served to the public: short-neck clam (Ruditapes philippinarum, asari in Japanese), hard-shell clam (Meretrix lusoria, hamaguri), brackishwater clam (Cyrenidae, shijimi), and oyster (Crassostrea gigas, kaki). Our analyses demonstrated that approx. 3 pieces of microplastics were present per single shellfish, based on the division of the total number of pieces of microplastic obtained from all 4 types of shellfish by the total number of shellfish examined. Since health problems in humans due to microplastics have not yet been confirmed, further examinations of the effects of ingested microplastics are needed., Competing Interests: No potential conflict of interest relevant to this article was reported.

The mouse bioassay (MBA) for paralytic shellfish toxins (PSTs) in bivalves has been used as an official method in Japan. It is necessary to develop an alternative method to animal experiments in PSTs assay because 3Rs (Replacement, Reduction, and Refinement) of animal experiments are required from the animal welfare point of view. Various methods such as HPLC-FL, receptor binding assay, LC-MS/MS and ELISA have been established to detect PSTs without performing animal experiments. The present study was undertaken to develop a screening method using oligonucleotide lateral flow immunoassay (OLFIA) for detecting PSTs in bivalves. The screening level was defined as positive at 2 MU/g of MBA that is the half regulation limit of PSTs monitoring in Japan. All 20 positive (equal to or more than 2 MU/g) samples judged from MBA showed a positive reaction in the OLFIA. No positive samples resulted in a false negative reaction. The OLFIA exhibited high accuracy at 2 MU/g of screening criteria. The authors demonstrated here that the OLFIA can be useful for rapid detection of PSTs in bivalves.

Variation in arsenolipid concentrations was assessed in 18 seafood samples including fish, shellfish, and crustaceans purchased in Japan. Analyses were performed by high performance liquid chromatography-inductively coupled plasma mass spectrometry/electrospray ionization tandem mass spectrometry. Stable isotope ratios for nitrogen and carbon were also measured in the samples for obtaining trophic level information of the species. Arsenic-containing hydrocarbons (AsHCs) and arsenic-containing fatty acids (AsFAs) were detected in the seafood samples; the toxic AsHCs were found in all of the seafood samples with large variation in the concentrations (83 ± 73 ng As/g fw, coefficient of variation = 88%). Our previous point estimate of health risk of AsHCs intake via seafood consumption in Japan, based on average AsHC concentration in seafood, suggested insignificant risk, and the present study supports our previous estimate. AsHC concentrations significantly correlated with lipid content of the seafood samples (r = 0.67, p < 0.01), a result expected because of the fat solubility of the compounds. The AsHCs concentrations, however, were not significantly correlated with nitrogen stable isotope ratios suggesting that AsHCs do not biomagnify. The source of the observed large variation in AsHC concentrations will be the subject of further investigation., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The total mercury (T-Hg) and methylmercury (MeHg) concentrations in red snow crabs (Chionoecetes japonicus) caught off the coast of Japan were analyzed. The T-Hg concentration ranged from 0.03 to 0.56 mg/kg (mean: 0.21 mg/kg) in the raw muscle, and 0.02 to 0.74 mg/kg (mean: 0.27 mg/kg) in the boiled muscle. The MeHg concentration ranged from 0.04 to 0.54 mg/kg (mean: 0.20 mg/kg) in the raw muscle. The mean ratio of MeHg to T-Hg was 0.88. The crab body weight was found to significantly correlate with the concentrations of T-Hg (r = 0.488) and MeHg (r = 0.490) (p ≤ 0.01). For the general population in Japan, the intake of MeHg from eating red snow crab was estimated to be lower than 0.013 mg/week, which was less than one-sixth of the tolerable MeHg intake (0.08 mg/week)., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Seasonal dynamics and the distribution of dinophysistoxin-3 (DTX-3) in organs of mussel Crenomytilus grayanus, collected in 2013 in Peter the Great Bay, Sea of Japan, were determined. Active toxin forms (OA, DTX-1/2) concentrated in digestive glands (60-80%), whereas non-active 7-O-acyl derivatives (DTX-3) were more abundant in edible soft tissues (more than 80%). Possible mechanism of fast removing of DTX-3 from the digestive gland and accumulation of DTX-3 in the soft tissues is supposed., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Vibrio parahaemolyticus carrying the tdh gene, encoding the thermostable direct hemolysin (TDH), or the trh gene, encoding the TDH-related hemolysin (TRH), are both considered virulent strains. There are, however, disproportionally fewer reports of infections caused by seafood contaminated with trh-positive strains than by seafood contaminated with tdh-positive strains. Bivalves such as clams and oysters are the major seafood varieties associated with the infections. In this study, the prevalence of strains possessing the tdh and trh genes was investigated in Japan in 74 samples collected in 2007-2008 and in 177 samples collected in 2010 of domestic bivalves, bloody clams, hen clams, short-neck clams, and rock oysters. The tdh-positive and trh-negative, tdh-negative and trh-positive, and tdh-positive and trh-positive samples represented 5.4%, 12.2%, and 4.1% of all samples collected in 2007-2008, and 5.1%, 18.6%, and 5.6% of all samples collected in 2010, respectively. As determined by polymerase chain reaction, the prevalence of tdh negative and trh positive in all samples was two to four times higher than that of tdh positive and trh negative. In the samples collected in 2010, the tdh-negative and trh-positive V. parahaemolyticus (20 samples) was more often isolated than tdh-positive and trh-negative V. parahaemolyticus (7 samples). The most common serotype of tdh-positive isolates (22 of 24 strains) was pandemic O3:K6. The trh-positive isolates (61 strains) were various serotypes including OUT:KUT. In 330 V. parahaemolyticus outbreaks and sporadic infections in Japan, most outbreaks and sporadic infections were caused by tdh-positive and trh-negative strains (89.4%). The frequencies of infections caused by tdh-negative and trh-positive, and both tdh- and trh-positive strains were 1.2% and 3.0%, respectively. This finding suggests that the virulence of trh might be less than that of tdh, although trh-positive V. parahaemolyticus frequently contaminated bivalves.

The mouse bioassay (MBA) for paralytic shellfish poisoning (PSP) toxins has been used in the AOAC Official Method and the official Japanese method. In the AOAC Official Method, the saxitoxin (STX) standard provided by the U.S. Food and Drug Administration (FDA) is used, but no standard is used in the official Japanese method. The objective of this study was to compare the toxicity of decarbamoyl STX (dcSTX), one of the derivatives of STX and a candidate standard for the MBA for PSP toxins in Japan, to that of FDA STX in the MBA platform. In this study, the toxicity of dcSTX was 918.0 ± 44.9 mouse units/µmol, and the relative toxicity ratio of dcSTX to FDA STX based on moles was 0.478.

A labeling system for food allergenic ingredients was established in Japan in April 2002. To monitor the labeling, the Japanese government announced official methods for detecting allergens in processed foods in November 2002. The official methods consist of quantitative screening tests using enzyme-linked immunosorbent assays (ELISAs) and qualitative confirmation tests using Western blotting or polymerase chain reactions (PCR). In addition, the Japanese government designated 10 μg protein/g food (the corresponding allergenic ingredient soluble protein weight/food weight), determined by ELISA, as the labeling threshold. To standardize the official methods, the criteria for the validation protocol were described in the official guidelines. This paper, which was presented at the Advances in Food Allergen Detection Symposium, ACS National Meeting and Expo, San Diego, CA, Spring 2012, describes the validation protocol outlined in the official Japanese guidelines, the results of interlaboratory studies for the quantitative detection method (ELISA for crustacean proteins) and the qualitative detection method (PCR for shrimp and crab DNAs), and the reliability of the detection methods.

Selenium is an essential micronutrient for humans, and seafood is one of the major selenium sources, as well as red meat, grains, eggs, chicken, liver and garlic. A substantial proportion of the total amount of selenium is present as selenium containing imidazole compound, selenoneine, in the muscles of ocean fish. In order to characterize the selenium content in seafood, the total selenium levels were measured in the edible portions of commercially important fish and shellfish species. Among the tested edible portions, alfonsino muscle had the highest selenium levels (concentration of 1.27 mg/kg tissue). High levels of selenium (1.20-1.07 mg/kg) were also found in the salted ovary products of mullet and Pacific herring. In other fish muscles, the selenium levels ranged between 0.12 and 0.77 mg/kg tissue. The selenium levels were closely correlated with the mercury levels in the white and red muscles in alfonsino. The selenium content in spleen, blood, hepatopancreas, heart, red muscle, white muscle, brain, ovary and testis ranged between 1.10 and 24.8 mg/kg tissue in alfonsino.

A method of rapid analysis of multi-class residual veterinary drugs in milk, fish and shellfish was validated in accordance with Japanese guidelines for the validation of analytical methods for residual agricultural chemicals in food. Using LC-MS/MS, 43 multi-class veterinary drugs, including sulfonamides, quinolones, coccidiostats and antiparasites, could be analyzed in one injection. Analytes were extracted from samples with two kinds of solvent, acetonitrile containing 1 vol% formic acid and anhydrous acetonitrile, and salted out with 4.0 g of magnesium sulfate, 1.5 g of trisodium citrate and 2.0 g of sodium chloride. This method was assessed by performing recovery tests in retail milk and 4 kinds of fresh cultured fish and shellfish (salmon, tiger shrimp, red sea bream and bastard halibut) spiked with the 43 target analytes at the levels of 10 and 100 μg/kg. Using this method, 40 out of 43 drugs satisfied the guideline criteria in milk, 37 drugs in salmon, 42 drugs in tiger shrimp, 41 drugs in red sea bream and 39 drugs in bastard halibut.

The pathway and radiological impact of the radioactive plume released at the Fukushima nuclear accident site on the Korean Peninsula has been studied. On March 28, 2011, only (131)I was first observed at all 12 regional monitoring stations in Korea, and the highest activity concentrations in aerosol were 3.12 mBq/m(3) for (131)I at Gunsan, 1.19 mBq/m(3) for (134)Cs and 1.25 mBq/m(3) for (137)Cs at Busan on April 7, 2011. These radionuclides were also detected in dry and wet deposition samples, while the significant increase of (131)I, (134)Cs and (137)Cs activity concentrations were not observed in seawater and marine biota samples., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The contents of six natural vitamin B(6) forms in popular Japanese sushi toppings were determined by a 4-pyridoxolactone-conversion HPLC method. The half-baked bonito exhibited the highest total vitamin B(6) content and the northern shrimp sashimi the lowest. Pyridoxal 5'-phosphate plus pyridoxal was predominant in nine samples, and pyridoxamine 5'-phosphate plus pyridoxamine in two other samples. Pyridoxine 5'-phosphate plus pyridoxine was minor. The raw meats (sashimi) of fatty seawater fishes contain a lot of pyridoxal 5'-phosphate and/or pyridoxamine 5'-phosphate. Five portions of sushi with 20 g of fatty seawater sashimi toppings would supply with vitamin B(6) recommended by the Japanese Recommended Daily Allowance.

A survey of 29 pesticides were performed for water, fish and shellfish from two littoral areas of Lake Biwa and Yanamune River in 2007. Three insecticides, 5 fungicides and 13 herbicides were detected in the water from the sampling locations, but the insecticides and fungicides were not and the only 9 herbicides were detected in the fish and shellfish from the locations. Bioconcentration factors (BCF) of the 9 herbicides in the fish and shellfish were calculated by the field data obtained from the survey. The average field BCF values of the herbicides in the fish were 8 and 25 for molinate, 5-23 for bromobutide, 4 and 10 for simetryn, 100-214 for esprocarb, 15-41 for pretilachlor, 148 for anilofos, 14 and 79 for mefenacet and 78 for cafenstrole. Those in the shellfish were 6 and 13 for bromobutide, 4 and 8 for simetryn, 67 and 135 for esprocarb, 2 for pretilachlor, 117 for pyributicarb and 57 and 139 for mefenacet. The field BCF data in the fish were evaluated by laboratory BCF data from literatures for molinate, bromobutide, pretilachlor, simetryn and mefenacet.

This study presents the results of a total diet study performed for estimating the dietary intake of polybrominated diphenyl ethers (PBDEs) in Osaka, Japan. The concentrations of 36 PBDEs were measured in samples from 14 food groups (Groups I-XIV). PBDEs were detected only in Groups IV (oils and fats), V (legumes and their products), X (fish, shellfish, and their products), and XI (meat and eggs) at concentrations of 1.8, 0.03, 0.48, and 0.01 ng g⁻¹, respectively. For an average person, the lower bound dietary intakes of penta- and deca-formulations were estimated to be 46 and 21 ng day⁻¹, respectively. A high proportion of the decabrominated congener (DeBDE-209) was observed in Group IV. To confirm the presence of DeBDE-209 in vegetable oils, an additional analysis was performed using 18 vegetable oil samples. Of these, seven contained ng g⁻¹ levels of DeBDE-209.

To assess levels of shellfish intoxication by the paralytic shellfish poison (PSP)-producing dinoflagellate Alexandrium tamarense, potential health risks to human shellfish consumers and the possible need for regulatory intervention, yearly variations of maximum cell density of this species were examined from 1993 to 2004 in Kure Bay and Kaita Bay, which are located within Hiroshima Bay, Hiroshima Prefecture, Japan. The seawater temperature was determined concomitantly. In Kure Bay, maximum concentrations of 1,400 and 1,300 cells/mL at 0 and 5 m depths were observed on 21 and 24 April 1997. In Kaita Bay, remarkably high concentrations above 1,000 cells/mL of A. tamarense were observed in two out of three years investigated. These facts suggest that the environment in both bays is favorable for the propagation of A. tamarense. The temperature range at which the natural population of A. tamarense blooms was generally from 12 to 16 degrees C. Four strains (ATKR-94, -95, -97 and -01) from Kure Bay and one strain (ATKT-97) from Kaita Bay were established. The strain ATKR-94, cultured in modified SW-2 medium at 15 degrees C for 15 days, showed a specific toxicity of 33.8 x 10(-6) MU/cell. The toxins in all five strains exist almost exclusively as beta-epimers (C2 (PX2 or GTX8), GTX3, dcGTX3 and GTX4), which accounted for 54.9 to 73.0 mol% of the total. The corresponding a-epimers (C1 (PX1 or epi-GTX8), GTX2, dcGTX2 and GTX1) accounted for 6.0 to 28.9 mol%. The toxin profiles of ATKR-97 and ATKT-97 were characterized by unusually high proportions of low-potency sulfocarbamoyl toxin, which comprised 62.4 and 68.2 mol%, respectively, of total toxins. In the toxic bivalves, the low-toxicity sulfocarbamoyl components, major components of A. tamarense, were present in amounts of only a few percent, suggesting that in vivo conversion of PSP occurs after ingestion. A comparison of the toxin profiles of the causative dinoflagellate and contaminated bivalves showed that PSP components exist in the bivalves in the form of alpha-epimers, presumably owing to accumulation or storage of the toxins.

In 1993, the Japanese government set the guideline concentration of 2 microg l(-1) for antimony in natural water and drinking water as an item for precautionary monitoring in consideration of its chronic toxicity, however in 1999 the guideline value was tentatively canceled to examine the health risk of antimony through the accumulation of more information and data for detailed risk assessment. In this study, the distribution of antimony in the river water environment including water, sediment, aquatic plants and fishes was surveyed in the Yodo River basin. The characteristics of antimony distribution between river water and sediment were determined by the batch sorption experiments, focusing on the difference in oxidation state. This study suggests that biota in the Yodo River basin have antimony at concentrated levels. Some of the sewage treatment plants seemed to influence the concentration of antimony in river water. It was shown that the pentavalent antimony is dominant in river water and especially paramount downstream of the sewage treatment plants, though the trivalent antimony is dominant in industrial use. According to the sorption experiments of antimony on river sediment, the trivalent antimony is sorbed faster and more in partition than the pentavalent antimony.

S-421 is a synergist for pyrethroid and organophosphorus pesticides, and is widely used in termiticides or commercial household insecticides. S-421 is mutagenic, stable and ubiquitous in the environment, and has been detected in household dust, surface water, sediments and rain-water. Here we describe the concentration of S-421 residues in domestic and imported fish collected in Osaka. S-421 was extracted with acetone/hexane, purified through silica gel 40 and quantified by ECD-GC. S-421 was detected in 36 out of 44 samples of domestic fish and shellfish analyzed, at a level of < 0.2 to 2.3 ng/g (mean: 0.6 ng/g), and in 27 out of 43 imported samples at a level of < 0.2 to 1.0 ng/g (mean: 0.2 ng/g). The levels of S-421 detected in fish were lower than those of DDTs and almost the same as those of HCHs. More attention should be paid to the behavior in the environment of S-421, as well as other persistent organochlorine pollutants, such as HCHs, DDTs and chlordane.

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.

A survey of residual antibiotic agents in cultured fish and shellfish purchased from the Tokyo Central Market was carried out. Out of 240 samples tested, OTC was detected in 14 samples which consisted of flatfish, yellowtail, seriola and eel. Synthetic antibiotic agents were not detected. The highest level of OTC was 0.36 microgram/g in skin of flatfish. In the case of flatfish, the concentration of OTC was highest in skin, followed by liver, then muscle. OTC was detected in livers of all yellowtail, seriola and eel, and the concentration was higher than that in muscle or skin.

The biosensor consisted of a sodium electrode and covered with the frog bladder membrane within a flow cell was tested for the estimation of tetrodotoxin (TTX) and saxitoxin (STX). This sensor was applied to detect very low amounts of the Na+ channel blockers, STX and TTX, in different shellfishes and swellfishes. A good agreement was obtained between TTX activities determined by mouse assay and amounts of Na+ channel blockers estimated by frog membrane sensor. The lowest level of TTX (fg) that can be determined by frog membrane sensor does not cause human poisoning. The channel blockers in short-necked clam, which was assumed to be STX, were monitored by this sensor continuously every week for one year. It was discovered that the STX content increased from July until September and then decreased from October until March. The biosensor proposed here may be used for the estimation of STX and TTX conventionally in the future.

In the present study the levels of the organotin compounds were determined in fish and shellfish which were purchased from retail markets in Niigata, Japan. The concentrations of dibutyltin (DBT), tributyltin (TBT), diphenyltin (DPT) and triphenyltin (TPT) compounds were separately determined by FPD-gas chromatography. Eight species (yellowtail, tuna, cuttlefish, olive flounder, northern shrimp, cinnamon flounder, Japanese sea bass and oyster) were studied and five samples of each species were analyzed in each season, which meant 40 samples in one season, and 160 in total. Among the compounds of interest, DBT, TBT and TPT were detected. The highest concentrations detected were 0.674 microgram/g for DBT, 0.669 microgram/g for TBT and 0.186 microgram/g for TPT. DBT was detected as much as TBT, however, its concentration was not correlated with that of TBT. Seasonal changes of the mean value of the concentration of DBT and TBT were observed. In some species, such as yellowtail and Japanese sea bass, combined contaminations of these organotin compounds were also evident. This study is the first step to elucidate possible health hazards by environmental pollution of organotin compounds on human beings.

Japanese research of taste-active components in seafoods, meat and tomatoes is reviewed. The omission (or addition) test with synthetic extracts simulating natural extracts was employed in most of that research. In abalone, sea-urchin, snow crab, scallop and short-necked clam, glutamic acid (Glu) and glycine were recognized commonly to be taste-active. It was also reported that the synergism between Glu and 5'-ribonucleotides and the presence of sodium and chloride ions were required to produce the characteristic taste of each food. In dried skipjack meat and salted salmon eggs, umami substances such as Glu and inosine 5'-monophosphate (IMP) were found to be important contributors to their tastes as well. The brothy taste of beef, pork and chicken soups could be reproduced by free amino acids, IMP and sodium chloride, indicating their important roles in producing the taste. A potential effect of Glu and aspartic acid on the taste of tomatoes was observed. Studies of the flavor-enhancing effects on soups and umami solutions of sulfur-containing compounds in garlic are also described.

A simple and accurate analytical method for determination of polycyclic aromatic hydrocarbons (PAHs) in fish and shellfish is presented, which is considered to be useful for routine analyses and for screening purposes. The procedure involves alkaline digestion, extraction with n-hexane, silica gel column chromatography, and liquid chromatographic (LC) determination with fluorometric detection. During development of the analytical method for determination of PAHs, it was found that benzo[a]pyrene, a representative PAH, was decomposed easily by the analytical procedure, and this tendency was investigated for the experimental conditions used. Benzo[a]pyrene was decomposed by the coexistence of alkaline conditions, light, and oxygen; by peroxides in aged ethyl ether; and by oxygen when absorbed on silica gel. Thus, to obtain good recoveries and precise analytical results, these decomposition conditions must be avoided. The following precautions are recommended: protection from light through all analytical steps; addition of Na2S to alkaline digestion mixture as an antioxidant; complete removal of peroxides from ethyl ether just before use; quick column chromatography on silica gel; and prevention of air from contact with adsorbent. When this simple method was applied to fish and shellfish samples, very good recoveries of PAHs from fortified fish samples were obtained, and no serious interferences were observed in fish and shellfish extracts.

The concentration of 60Co and stable cobalt in the shellfishes and seaweeds which were collected from the coast around Japan were obtained by low background beta counting for 60Co and spectrometric determination of stable cobalt. The results obtained were as follows: (1) The 60Co was found in the shellfishes which were enriched in the stable cobalt. (2) The correlation between 60Co and stable cobalt was rather good in the shellfishes. (3) The activities of 60Co was found in the seaweeds taken from seashore near the nuclear power plant. (4) There was great differences in the specific activities between samples collected from contaminated and not contaminated area.