Development and validation of a simulation method, PeCHREM, for evaluating spatio-temporal concentration changes of paddy herbicides in rivers.

In pesticide risk management in Japan, predicted environmental concentrations are estimated by a tiered approach, and the Ministry of the Environment also performs field surveys to confirm the maximum concentrations of pesticides with risk concerns. To contribute to more efficient and effective field surveys, we developed the Pesticide Chemicals High Resolution Estimation Method (PeCHREM) for estimating spatially and temporally variable emissions of various paddy herbicides from paddy fields to the environment. We used PeCHREM and the G-CIEMS multimedia environmental fate model to predict day-to-day environmental concentration changes of 25 herbicides throughout Japan. To validate the PeCHREM/G-CIEMS model, we also conducted a field survey, in which river waters were sampled at least once every two weeks at seven sites in six prefectures from April to July 2009. In 20 of 139 sampling site-herbicide combinations in which herbicides were detected in at least three samples, all observed concentrations differed from the corresponding prediction by less than one order of magnitude. We also compared peak concentrations and the dates on which the concentrations reached peak values (peak dates) between predictions and observations. The peak concentration differences between predictions and observations were less than one order of magnitude in 66% of the 166 sampling site-herbicide combinations in which herbicide was detected in river water. The observed and predicted peak dates differed by less than two weeks in 79% of these 166 combinations. These results confirm that the PeCHREM/G-CIEMS model can improve the efficiency and effectiveness of surveys by predicting the peak concentrations and peak dates of various herbicides.

Respiratory Uptake and Depuration Kinetics of Perfluorooctanesulfonate (PFOS) in a Marine Sandworm Species.

We determined the respiratory uptake and depuration kinetics of perfluorooctanesulfonate (PFOS) in Perinereis wilsoni, a polychaete sandworm used as a model species to investigate the fate of chemical pollutants in coastal environments. The sandworms were kept in gravel-packed containers, and the water levels were varied cyclically to mimic the tides. We used seawater kept at 17.1°C. A 7-day exposure period was followed by a 9-day depuration period. The dissolved PFOS concentration averaged 28 ng/L during the exposure period. Sandworm samples were collected regularly for analysis of PFOS concentrations, and a first-order-kinetics model was applied to the concentrations. The respiratory absorption efficiency of PFOS was estimated to be 11% that of oxygen, which is higher than the corresponding estimates reported for several fish species. The estimated depuration half-life of 15 days was comparable to previously reported estimates for fish and oligochaete species. The bioconcentration factor was 470.

Temporal trends for inflow of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) to Tokyo Bay, Japan, estimated by a receptor-oriented approach.

We estimated inflow rates of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) to Tokyo Bay, Japan, between February 2004 and February 2011 by a receptor-oriented approach based on quarterly samplings of the bay water. Temporal trends in these inflow rates are an important basis for evaluating changes in PFOS and PFOA emissions in the Tokyo Bay catchment basin. A mixing model estimated the average concentrations of these compounds in the freshwater inflow to the bay, which were then multiplied by estimated freshwater inflow rates to obtain the inflow rates of these compounds. The receptor-oriented approach enabled us to comprehensively cover inflow to the bay, including inflow via direct discharge to the bay. On a logarithmic basis, the rate of inflow for PFOS decreased gradually, particularly after 2006, whereas that for PFOA exhibited a marked stepwise decrease from 2006 to 2007. The rate of inflow for PFOS decreased from 730kg/y during 2004-2006 to 160kg/y in 2010, whereas that for PFOA decreased from 2000kg/y during 2004-2006 to 290kg/y in 2010. These reductions probably reflected reductions in the use and emission of these compounds and their precursors in the Tokyo Bay catchment basin. Our estimated per-person inflow rates (i.e., inflow rates divided by the estimated population in the basin) for PFOS were generally comparable to previously reported per-person waterborne emission rates in Japan and other countries, whereas those for PFOA were generally higher than previously reported per-person waterborne emission rates. A comparison with previous estimates of household emission rates of these compounds suggested that our inflow estimates included a considerable contribution from point industrial sources.

Transfer kinetics of perfluorooctane sulfonate from water and sediment to a marine benthic fish, the marbled flounder (Pseudopleuronectes yokohamae).

The authors investigated the kinetics of transfer of perfluorooctane sulfonate (PFOS) from water, suspended sediment, and bottom sediment to a marine benthic fish, the marbled flounder (Pseudopleuronectes yokohamae). Fish were exposed in 3 treatments to PFOS in combinations of these exposure media for 28 d and then depurated for 84 d. A major part (37-66%) of PFOS in the fish was in the carcass (i.e., whole body minus muscle and internal organs). Three first-order-kinetic models that differed in exposure media, that is, 1) sum of dissolved and particulate phases and sediment; 2) dissolved phase, particulate phase, and sediment; and 3) dissolved phase only, were fitted to the data assuming common rate constants among the treatments. The uptake efficiency of dissolved PFOS at the respiratory surfaces was estimated to be 3.2% that of oxygen, and the half-life of PFOS in the whole body to be 29 d to 31 d. The better fit of models 1 and 2 and the values of the estimated uptake rate constants suggested that the PFOS in suspended and bottom sediments, in addition to that dissolved in water, contributed to the observed body burden of the fish. Based on an evaluation of several possible contributing factors to the uptake of PFOS from suspended and bottom sediments, the authors propose that further investigation is necessary regarding the mechanisms responsible for the uptake.

Prenatal exposure to phthalate esters and PAHs and birth outcomes.

The purpose of this study was to investigate the relationship between the levels of prenatal exposure to phthalate ester and PAHs and birth outcomes among 149 Japanese pregnant women. Urinary concentrations of 9 phthalate ester metabolites, mono methyl phthalate (MMP), mono ethyl phthalate (MEP), mono-n-butyl phthalate (MnBP), mono benzyl phthalate (MBzP), mono-2-ethylhexyl phthalate (MEHP), mono-2-ethyl-5-hydroxyhexyl phthalate (MEHHP), mono-2-ethyl-5-oxohexyl phthalate (MEOHP), mono-iso-nonyl phthalate (MINP) and mono-n-octyl phthalate (MnOP) and PAHs metabolite (1-hydroxypyrene, 1-OHP) were analyzed in spot urine samples collected from pregnant women. Correlation analysis and multiple regression analysis were conducted between the concentrations of maternal urinary metabolites and birth outcomes such as birth weight, birth length, head circumference and gestational age. Creatinine-corrected concentration (geometric mean; microg/g cre) was 9.14 (MMP), 9.76 (MEP), 51.6 (MnBP), 5.62 (MBzP), 5.45 (MEHP), 10.6 (MEHHP), 11.3 (MEOHP), 0.031 (MINP), 0.025 (MnOP) and 0.121 (1-OHP). These concentrations are comparable with literature value. The relationships between prenatal exposure to phthalate esters and birth outcomes were not significant. Statistically significant negative correlation was observed between 1-OHP and birth weight, birth length and head circumstances although the correlation was insignificant when only non-smokers were included in multiple regression analysis. In conclusion, we found that prenatal exposure to phthalate esters or PAHs did not affect birth outcomes at the exposure level of the present subjects.

Spatial, phase, and temporal distributions of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in Tokyo Bay, Japan.

The spatial distribution, partitioning, and time trends of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) were investigated in the water column and bottom sediment of Tokyo Bay, Japan, during 2004-2006. A total of 480 water and 60 sediment samples obtained by regular 20-station samplings ascertained the three-dimensional distributions of these compounds and changes in the seawater structure in the whole bay. The median of volume-based average water-borne concentrations of PFOS and PFOA was 3.7 and 12 ng/L, respectively. The median concentrations in sediment were 0.61 (PFOS) and 0.20 (PFOA) ng/g-dry. Vertical mixing of the water column probably affected the vertical distribution of these compounds. The negative correlations between PFOS and PFOA concentrations and water salinity and the horizontal distributions of their concentrations suggested that freshwater inputs into the bay were the source of these compounds. A mixing model estimated the average PFOS concentration in the freshwater inputs to be 29 ng/L. The common logarithm of the partition coefficients between the dissolved and suspended-particle-sorbed phases varied among samples, with the average of 4.2 (PFOS) and 3.5 (PFOA). Our analyses indicated no apparent time trends in the concentrations of these compounds during 2004-2006 in either the freshwater input or the bay.

Spatial distribution and partitioning of polychlorinated biphenyls in Tokyo Bay, Japan.

Spatial distributions and partitioning of polychlorinated biphenyls (PCBs) in Tokyo Bay, Japan, were evaluated by measuring the concentrations of all 209 PCB congeners in surface and bottom waters and bottom sediment at 10 locations. The dissolved + particulate summed congener concentrations (SigmaPCB [sum of the concentrations of all 209 PCB congeners]) in surface and bottom waters ranged from 120 to 1100 pg L(-1) (median 250 pg L(-1)) and from 83 to 910 pg L(-1) (median 230 pg L(-1)), respectively. The concentrations did not statistically differ between the two layers, possibly because of vertical mixing of the water column. SigmaPCB concentrations in sediment ranged from 2.7 to 110 ng g(-1)-dry weight. The highest SigmaPCB concentrations in both water and sediment were found at stations in the northern bay. Logarithms of field-observed organic carbon-normalized partition coefficients (K(OC)) increased linearly as the log octanol-water partition coefficients (K(OW)) increased, up to a log K(OW) of about 6.5, and then decreased for log K(OW) > 6.5 (mostly hexa- and hepta-chlorinated biphenyls). Furthermore, log K(OC) values of congeners having log K(OW) < 6.5 were higher by about 1 than values predicted by a published empirically derived equation, suggesting that application of K(OC) values determined in laboratory experiments with soil or sediment samples to fate prediction models may result in overestimation by about one order of magnitude of the concentrations of PCBs with log K(OW) < 6.5 in the dissolved phase in the water column.

Impaired megabenthic community structure caused by summer hypoxia in a eutrophic coastal bay.

Eutrophication and hypoxia are major problems affecting the health of coastal ecosystems throughout the world. Tokyo Bay, Japan, is a eutrophic coastal area where the abundance of the megabenthic community has been decreasing. To assess factors associated with the impaired biota, seasonal surveys of the megabenthic community and water and sediment quality were conducted in the bay. Cluster analysis showed a difference in the community structure between the northern and southern parts of the bay. The density of species and species diversity were high throughout the year in the southern part of the bay, whereas in the northern part of the bay species diversity was low and defaunation occurred in August. At this time, bottom hypoxia due to temperature and salinity stratification, and high concentrations of nutrients, chlorophyll a, and organic matter in the water column and/or sediment, dominated the northern part of the bay. In October, bottom hypoxia was less severe but was still present in the northern part of the bay, and recolonization by mobile fishes and sessile mussels occurred. Multivariate analyses of the megabenthic community and environmental parameters in August showed the spatial pattern of the community could be explained by concentrations of dissolved oxygen and particulate organic carbon in the bottom water, and total sulfide and total organic carbon in the sediments. In particular, impairment of the biota in the northern area could be explained by the threshold concentrations of dissolved oxygen < 1.7 mL L(-1) and total organic carbon > 20.3 mg g(-1).

Exposure assessment of phthalate esters in Japanese pregnant women by using urinary metabolite analysis.

OBJECTIVES: Our objectives were (1) to evaluate whether single spot urine is suitable media for longer-term phthalate esters exposure assessment, and (2) to estimate intake level of phthalate esters of Japanese pregnant women using urinary metabolites as an indicator of prenatal exposure level in their offspring. METHODS: We analyzed nine metabolites (MMP, MEP, MnBP, MBzP, MEHP, MEOHP, MEHHP, MINP, MnOP) of seven phthalate esters in spot urine samples from 50 pregnant women by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Using four urine samples collected from each of 12 subjects from 50 pregnant women within 5-12 weeks, we compared intra- and interindividual variation in urinary metabolites by calculation of intraclass correlation coefficient (ICC). We estimated daily intakes of 50 pregnant women from their urinary metabolite concentrations. RESULTS: ICCs for seven phthalate metabolite concentrations in single spot urine samples were: MMP (0.57), MEP (0.47), MnBP (0.69), MBzP (0.28), MEHP (0.51), MEHHP (0.43), and MEOHP (0.41) in 12 pregnant women. Phthalate ester metabolites had high detection rates in 50 subjects. The mean daily intake ranged from 0.01 to 2 mug/kg per day. The daily intake levels in all subjects were lower than corresponding tolerable daily intake (TDI) set by the European Food Safety Authority (EFSA), though maximum value for DnBP of 6.91 mug/kg per day accounted for 70% of TDI value. CONCLUSIONS: Higher ICCs indicated that phthalate metabolite levels in single spot urine could reflect longer-term exposure to the corresponding diesters of subjects. Although the current exposure level was less than TDIs, further studies and exposure monitoring are needed to reveal the toxicity of phthalate esters to sensitive subpopulation.

[Estimation of intake level of di (2-ethyhexyl) phthalate (DEHP) in Japanese pregnant women based on measurement of concentrations of three urinary metabolites].

OBJECTIVES: [corrected] The daily intake level of di (2-ethyhexyl) phthalate (DEHP) of Japanese pregnant women was estimated on the basis of the measurement of the urinary concentrations of three DEHP metabolites. METHODS: Spot urine samples were collected from 42 pregnant women who visited the gynecology division of a hospital for routine health check between June and October, 2003. The urinary concentrations of three DEHP metabolites, namely, mono (2-ethyhexyl) phthalate (MEHP), mono (2-ethy-5-hydroxyhexyl) phthalate (MEHHP), and mono (2-ethyl-5-oxohexyl) phthalate (MEOHP) were measured by HPLC/MS/MS. RESULTS: The concentrations of urinary MEHP, MEOHP and MEHHP (n=40) were 3.27-39.5 (median 9.83), 1.51-41.0 (median 10.4) and 4.6-26.6 (median 10.9) microg/g cre, respectively. The ranges of the estimated daily intake of DEHP per body weight based on the MEHP, MEOHP and MEHHP concentrations (n=40) were 3.45-41.6 (median 10.4), 0.66-17.9 (median 4.55) and 1.47-8.57 (median 3.51) microg/kg/day, respectively. The maximum estimated intake level per body weight (41.6 microg/kg/day) reached the Tolerable Daily Intake (TDI) level of 40-140 microg/kg/day set by the Ministry of Health and Welfare (now the Ministry of Health, Labour and Welfare). CONCLUSIONS: The health risk of DEHP exposure of our study subjects was found to be minimum from the viewpoint of the current knowledge of its risk level, although the human health effects of low-level DEHP exposure have to be studied further.

Horizontal distribution of steroid estrogens in surface sediments in Tokyo Bay.

A monitoring survey was conducted to investigate the distribution of steroid estrogens and their conjugates in surface sediments of Tokyo Bay for the first time, which is known as one of the most heavily polluted marine embayments in the world. The surface sediment samples were collected at 20 locations covering the whole area of Tokyo Bay and analyzed for steroid estrogens and their conjugates using liquid chromatography-tandem mass spectrometry. The concentrations of 17beta-estradiol (beta-E2) and estrone (E1) ranged from ND (below the detection limit; <0.07) to 0.59 and from 0.05 to 3.60 ng g-1 dry, respectively. Those concentrations were higher in the northern part of the bay, which is directly receiving huge quantities of pollutants from adjacent rivers containing a large amount of municipal and industrial wastewater. 17alpha-Estradiol (alpha-E2) and estrone-3-sulfate (E1-3S) were detected in some of the samples, whereas neither of the other conjugates, estriol (E3) or 17alpha-ethynylestradiol (EE2), was found.

Daily urinary excretion of bisphenol A.

OBJECTIVES: Concerns over dietary exposure to bisphenol A (BPA), an endocrine disruptor, have been raised because BPA is contained in resins and plastics commonly used for the preservation of food and beverages. The purpose of the present study was to assess daily intake levels of BPA in a group of male subjects by measuring total urinary BPA (free BPA plus BPA released by treatment with ß-glucuronidase), as well as determining intra-individual variation in BPA excretion. METHODS: Twenty-four-hour urine was collected from 5 subjects for 5 consecutive days for the evaluation of between-day variation in urinary BPA excretion and from 36 male subjects for the estimation of the level of daily BPA intake. BPA in the urine samples was measured by GC/MS/MS following enzymatic hydrolysis of BPA glucuronate, solid phase extraction, and derivatization. RESULTS: A large between-day variation was found over 5 days for the daily excretion of urinary BPA in the 5 subjects. The daily excretion of urinary BPA was distributed log-normally in the 36 male subjects, with the median value being 1.2 µg/day (range: <0.21-14 µg/day), which was far below the Tolerable Daily Intake (0.01 mg/kg bw) recommended by a scientific committee in the European Commission in 2002. However, the maximum estimated intake per body weight (0.2 µg/kg/day) was only one order of magnitude lower than the reported lowest level for reproductive/behavioral effects in pregnant mice (2 µg/kg/day). CONCLUSIONS: Measuring urinary BPA in urine is a suitable approach for estimating short-term BPA intake levels in individuals and/or estimating the average exposure level of populations. Urine analyses will be increasingly important in the human health risk assessment of BPA.

[Estimation of intake level of bisphenol A in Japanese pregnant women based on measurement of urinary excretion level of the metabolite].

OBJECTIVE: The daily bisphenol A (BPA) intake level of Japanese pregnant women was surveyed based on the measurement of the urinary excretion level of a BPA metabolite. METHODS: Spot urine samples were collected from 56 pregnant women who visited the gynecology division of a hospital for a routine health check between June and October 2003. The urinary concentrations of the BPA metabolite and creatinine were measured by GC/MS/MS and spectrophotometry, respectively. Daily BPA intake was assumed to be equal to daily excretion. RESULTS: The daily intake of BPA among Japanese pregnant women was estimated to be in the range of < 0.3 to 7.9 microg/day (median < 2.0 microg/day), being consistent with the levels in previous studies for non-pregnant Japanese women. This level was far below the current Acceptable Daily Intake (0.01 mg/kg/day) which was set by the European Commission. The maximum estimated intake per body weight (0.16 microg/kg/day) reached 1/10 of the Lowest Adverse Effect Level of BPA for pregnant mice for a reproductive effect on the offspring (2 microg/kg/day). CONCLUSION: It is desirable to lessen BPA intake from a precautionary viewpoint, particularly in pregnant women.

Processing of bisphenol A by plant tissues: glucosylation by cultured BY-2 cells and glucosylation/translocation by plants of Nicotiana tabacum.

Bisphenol A (BPA, 4,4'-isopropylidenediphenol), an endocrine disrupter with estrogenic properties, was supplied to tobacco BY-2 cells in suspension culture and the chemical nature of its metabolites was investigated. The concentration of BPA in the culture medium decreased rapidly and became undetectable at 2.5 h after the application. Four metabolites of BPA were observed in a methanol extract of the cells when the culture was supplemented with [(14)C]BPA. The most abundant metabolite was determined to be 4,4'-isopropylidenediphenol-O-beta-D-glucopyranoside (BPAG) by mass spectrometry, nuclear magnetic resonance spectroscopy and by hydrolysis with beta-glucosidase. This identification was confirmed by synthesis. When [(14)C]BPA was administrated to tobacco seedlings from their roots, radioactivity was incorporated in BPAG and three unidentified metabolites. These metabolites were accumulated in the leaves after 4 h exposure, indicating that tobacco seedlings absorbed BPA through their root systems, metabolized to its beta-glucoside and translocated the metabolites to their leaves.