Polychlorinated Biphenyl Concentrations and Estimated Intakes in Fish Oil Supplements on the Japanese Market.

Polychlorinated biphenyls (PCBs) are synthetic organic contaminants that are widespread in the environment. There are 209 PCB congeners. Fish oil produced from marine fish is widely used as a health supplement. PCB contamination of fish oil is of concern. We determined the concentrations of all 209 PCB congeners in commercially available fish oil supplements from Japan and estimated PCB intakes for humans consuming the supplements. We determined the concentrations of non-dioxin-like PCBs separately. The total PCB concentrations in 37 fish oil supplements purchased in Japan were 0.024-19 ng/g whole weight, and the non-dioxin-like PCB concentration range was also 0.024-19 ng/g whole weight. The total PCB intakes calculated for a 50 kg human consuming the supplements were 0.039-51 ng/day (0.00078-1.0 ng/(kg body weight per day)) and the non-dioxin-like PCB intake range was also 0.039-51 ng/day (0.00078-1.0 ng/(kg body weight per day)). The total PCB intakes were much lower than the tolerable daily intake of 20 ng/(kg body weight per day) recommended by the WHO. The results indicated that PCBs in the fish oil supplements pose acceptable risks to humans consuming the fish oil supplements daily.

Dietary intake of dioxins in Japan in 2016 with time trends since 1998.

Total diet samples collected from seven regions throughout Japan in 2016 were analysed for polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and dioxin-like polychlorinated biphenyls (DL-PCBs), known collectively as dioxins. This led to estimates of the latest dietary intake of these contaminants for the general Japanese population (≥1 year old). The average daily intake of dioxins for a person weighing 50 kg, calculated at non-detected congener concentrations assumed to be equal to zero, was estimated to be 0.54 pg TEQ (toxic equivalents) kg-1 body weight (bw) day-1. This value is well below the tolerable daily intake of 4 pg TEQ kg-1 bw day-1 for dioxins in Japan. The average intake was highest from fish and shellfish, followed by meat and eggs. The TEQ contribution of the fish and shellfish group to the total dietary TEQs was significant (89%). The DL-PCBs accounted for about 67% of the dioxin intake. The latest dioxin intake level was compared with previous estimates from total diet study results obtained annually since 1998 to determine the time trends in the dietary intake of dioxins in Japan. Overall, the average dioxin intake appeared to be decreasing gradually during the period of study. The previous average intakes of dioxins ranged from 0.58 to 1.9 pg TEQ kg-1 bw day-1. The latest average intake was the lowest since 1998 and was about one-third of the average intake in 1998. This decreasing trend in the dietary intake of dioxins was mainly influenced by the decreased dioxin intakes from two food groups, fish and shellfish, and meat and eggs.

Dioxin concentrations in dietary supplements containing animal oil on the Japanese market between 2007 and 2014.

We determined the concentrations of dioxins (polychlorinated dibenzo-p-dioxins, dibenzofurans and dioxin-like polychlorinated biphenyls) in 46 dietary supplement products, containing the oil of fish, marine mammals, or egg yolk, on the Japanese market between 2007 and 2014. Dioxins were detected in 43 of the 46 products tested at concentrations from 0.00015 to 67 pg TEQ/g. The highest concentration of dioxins was found in a shark liver oil product which varied insignificantly in five batches collected over a two-year period. The dioxin intakes from these five batches reached 2.3-2.8 pg TEQ/kg bw/day, or 58%-70%, respectively, of the Japanese tolerable daily intake (TDI) of 4 pg TEQ/kg bw/day. However, the dioxin intakes from most of the other products tested were less than 5% of the TDI. Although rare, supplements based on animal oils may contain relatively high concentrations of dioxins, leading to a substantial increase in dioxin intakes.

Determination of polychlorinated biphenyls in marine fish obtained from tsunami-stricken areas of Japan.

We determined the polychlorinated biphenyl (PCB) congeners in 101 marine fish obtained from tsunami-stricken areas following the Great East Japan Earthquake in 2011. In particular, to determine the degree of PCB contamination in the fish, we investigated the concentration of total PCB (∑PCB) and the proportions of 209 individual PCB congeners by high-resolution gas chromatography/high-resolution mass spectrometry. The ∑PCB concentration was 1.7-33 ng/g in fat greenling (n = 29), 0.44-25 ng/g in flounder (n = 36), and 1.6-86 ng/g in mackerel (n = 36), all values being much lower than the provisional regulatory limit in Japan. In the congener analysis, tetra-, penta-, hexa-, and hepta-chlorinated PCB congeners dominated in all samples (comprising over 86% of the ∑PCB). The proportions of the chlorinated PCB congeners were similar to the contamination patterns derived from Kanechlor in the environment, implying that the marine fish were not contaminated with fresh PCBs.

[Application of electron spin resonance spectroscopy for the detection of irradiated crustaceans (prawn, shrimp, and crabs)].

Prawn, shrimp and crabs sold in Japan are mostly imported from overseas. Detection of irradiated crustaceans is very important for quality assurance. In this study, we used ESR to detect radiation-induced radicals after irradiation of prawn, shrimp and crabs of major species. No radiation-induced radicals were detected in prawn (black tiger prawn) or shrimp (white leg shrimp). Radiation-induced radicals due to hydroxyapatite were detected in the claws of snow crab, red king crab, and swimming crab. Our results indicate that ESR measurement on the claw parts of these three species of crab can be used to determine their irradiation history.

Evaluation of an analytical method for cyanogenic compounds in beans and surveillance of cyanogenic compounds in beans.

The performance characteristics of an analytical method for cyanogenic compounds were evaluated. Specifically, we tested the trueness, repeatability and intermediate precision of the method using a spectrophotometric-based detection system for 4-pyridinecarboxylic acid and pyrazolone after steam distillation. The pH adjustment of the distillate was revealed to affect the trueness of the measurements. A pH of approximately 6 was found to be optimal. The targeted quantitation limit of the cyanide ion was set to 5 mg/kg. The performance of the method was evaluated using beans spiked with cyanide ion at one to two times the quantitation limit (5-10 mg/kg). The trueness of the method was between 78-90%, and the repeatability and intermediate precision were between RSD 1.2% to 6.0%. A surveillance of cyanogenic compounds in beans retailed in Japan was then carried out. All the results were below the quantitation limit of 5 mg/kg.

[Surveillance of perchlorate level in wine, seafood, polished rice, milk, powdered milk and yogurt].

Perchlorate, which may be naturally occurring or artificial in origin, inhibits iodide uptake into the thyroid gland and disturbs thyroid function. In order to investigate perchlorate contamination in foods in Japan, perchlorate levels in 28 wine samples, 20 seafood samples, 10 polished rice samples, 30 milk (include whole milk, composition modified milk, low fat milk, processed milk, milk drink) samples, 10 powdered milk samples and 10 yogurt samples were measured. Perchlorate was found in all wine, milk, powdered milk and yogurt samples tested. Perchlorate levels ranged from 0.2 ng/g to 103 ng/g in wine samples, from 2 ng/g to 11 ng/g in milk samples, from 3 ng/g to 35 ng/g in powdered milk samples, and from 2 ng/g to 11 ng/g in yogurt samples. Perchlorate levels in the seafood samples were under the LOQ (0.8 ng/g) in 8 samples and ranged from 0.8 ng/g to 72 ng/g in 12 samples. In all polished rice samples, perchlorate level was under the LOQ (1.0 ng/g).

[Surveillance of perchlorate level in leafy vegetables and bottled water].

Perchlorate (ClO(4)(-)) is both a naturally occurring and artificial compound, and it inhibits iodide uptake into the thyroid gland and disturbs thyroid function. It has been detected in many foods in the United States. In order to investigate perchlorate contamination in foods in Japan, perchlorate level in 82 leafy vegetable samples and 20 bottled mineral water samples was measured using a procedure based on the FDA's procedure, employing IC-MS/MS with (18)O(4)-labeled perchlorate as an internal standard. Among 82 leafy vegetable samples tested, perchlorate levels were under the LOQ (0.3 ng/g) in 3 samples and ranged from 0.3 ng/g to 29.7 ng/g in 79 samples. In 20 bottled water samples, perchlorate was under the LOQ (0.1 ng/mL) in 14 samples and ranged from 0.14 ng/mL to 0.35 ng/mL in 6 samples.

[Analytical method of dodine in agricultural products by LC/MS].

A method for the determination of dodine in agricultural products was developed by using liquid chromatography-electrospray ionization mass spectrometry (LC/ESI-MS). Dodine was extracted with acetonitrile and then acetonitrile-water (7 : 3) from a sample, and re-extracted with ethyl acetate. The extract was cleaned up on a PSA cartridge column (500 mg), and dodine was analyzed by LC/MS. In the case of oil seeds and nuts, hexane/acetonitrile-hydrochloric acid partition was performed to remove lipids before re-extraction with ethyl acetate. In the case of samples that contained a lot of chlorophyll, the eluate of the PSA cartridge column was further cleaned up on a graphitized carbon cartridge column (500 mg). The calibration curve was linear from 0.0001-0.02 microg/mL of dodine. The recoveries of dodine from sixteen kinds of agricultural products fortified at 0.1 mg/kg were 80.3-100.0%, and their relative standard deviations were 0.3-6.4%. The limits of detection (S/N=3) were 0.0006 mg/kg.

[Production of acrylamide in agricultural products by cooking].

Some model studies were performed using various agricultural Products, to clarify the relation between cooking conditions and production of acrylamide (AA). Disc chips made from dried mashed potato, corn meal, wheat flour, rice flour (jyohshin-ko) and glutinous rice flour (shiratama-ko), and dried sesame (arai-goma) and dried almond were baked at 120-200 degrees C for 5-20 min, and the samples were analyzed for the levels of AA. When the samples were baked for 10 min, the highest production of AA was observed at 180-200 degrees C. When the samples were baked at 180 degrees C, AA levels in agricultural products except sesame were highest after baking for 10 min. Vegetables and fruit were baked at 220 degrees C for 5 min with a oven, high AA concentrations were found in baked potato, asparagus, pumpkin, eggplant and green gram sprouts. Concentrations of AA in potato, asparagus and green gram sprouts baked after being pre-cooked by microwave irradiation were higher than those in the products baked without being precooked. On the other hand, the precooking by boiling reduced the production of AA by baking to 1/10-1/4. Acrylamide was not found in microwaved or boiled vegetables. High free asparagine concentrations in crops tended to result in high concentrations of AA being produced by heating the agricultural products.

Determination of acrylamide in processed foods by LC/MS using column switching.

An LC/MS method was developed for the determination of acrylamide (AA) in processed or cooked foods. AA was extracted with a mixture of water and acetone from homogenized food samples after the addition of 13C-labeled acrylamide (AA-1-(13)C) as an internal standard. The extract was concentrated, washed with dichloromethane for defatting, and cleaned up on Bond Elut C18, PSA and ACCUCAT cartridge-columns, and then AA was determined by LC/MS in the selected ion recording (SIR) mode. For the LC/MS analysis, four LC columns were connected in-line and the flow of the mobile phase was switched according to a time-program. Monitoring ions for AA were m/z 72 and 55, and those for AA-1-(13)C were m/z 73 and 56. AA and AA-1-(13)C were determined without interference from the matrices in all samples. The recoveries of AA from potato chips, corn snack, pretzel and roasted tea spiked at the level of 500 ng/g of AA were 99.5-101.0% with standard deviations (SD) in the range from 0.3 to 1.6%. The limits of detection and quantification of the developed method were 9 and 30 ng/g for AA in samples, respectively. The method was applied to the analysis of AA in various processed or cooked food samples purchased from retail markets. High levels of AA were found in potato chips and French-fried potato (467-3,544 ng/g). Fried and sugar-coated dough cakes (karinto) contained 374 and 1,895 ng/g. Corn snacks contained 117-535 ng/g of AA. Roasted foods (such as roasted sesame seed, roasted barley (mugi-cha), roasted tea (hoji-cha), coffee beans and curry powder) contained 116-567 ng/g of AA. Foods made from fish, egg and meat contained lower levels of AA than the plant-based foods. Foods containing much water showed a tendency to have low levels of AA compared with dry foods. The proposed method was applicable to the analysis of AA in variety of processed foods.

[Determination of ethychlozate and its degradation product in fruits by HPLC and LC/MS].

A method was developed for the analysis of ethychlozate (CIE) and its decomposition compound, 5-chloro-3(1H)-indazolylacetic acid (CIA) in fruits by HPLC and LC/MS. The sample was homogenized with 1 mol/L HC1, and CIE and CIA were extracted with 5 mol/L HCl and acetone. They were extracted from the acetone extract with diethylether-n-hexane (2:1). CIE was hydrolyzed to CIA with methanol-4 mol/L KOH (1:1). The solution was made acidic, and CIA was extracted with diethylether-n-hexane (2:1). The extract was cleaned up on a silica gel column. CIA was determined by HPLC-UV and LC/MS (Scan or SIR). Four fruits were spiked with CIE or CIA at 0.5 microgram/g and analyzed by the proposed method with HPLC. The average recoveries were 77.2-83.2% for CIE and 71.2-89.2% for CIA. The concentrations determined by LC/MS were 10-25% higher than the values by HPLC. The limit of detection (LOD) of CIA standard solution by HPLC corresponds to 0.015 microgram/g of CIE in the sample. In the same way, the LOD of CIA by LC/MS (SIR) corresponds to 0.009 microgram/g of CIE in the sample.

Determination of acrylamide in foods by GC/MS using 13C-labeled acrylamide as an internal standard.

A method was developed for the determination of trace amounts of acrylamide (AA) in foods. The method includes the addition of 13C-labeled acrylamide-1-13C (AA-1-13C) as an internal standard, extraction with water, bromination, clean-up with a Florisil cartridge column, dehydrobromination and GC/MS analysis in the selected ion monitoring (SIM) mode. Bromination of AA to 2,3-dibromopropionamide (2,3-DBPA) was done using potassium bromide and potassium bromate under an acidic condition. 2,3-DBPA was converted to 2-bromopropenamide (2-BPA) by dehydrobromination with triethylamine before GC/MS analysis. The recoveries of AA from spiked potato chips, corn snack, pretzel and roasted tea were 97-105%, and their relative standard deviations were 0.8-3.9%. The detection limit of AA in foods was 9 ng/g. The method was applied to thirty-one foods purchased from retail markets. AA was found in potato chips at the level of 466-3,340 ng/g, and in other foods at the level of ND-520 ng/g.