Shigeko Serizawa

Foetal exposure to phthalate esters and anogenital distance in male newborns.

Phthalate esters, commonly used as plasticizers, show anti-androgenic activity and cause male reproductive malformation in experimental animals. However, the effects of prenatal exposure to phthalate esters in humans have not been extensively studied. The purpose of this study was to examine the relationship between prenatal exposure to phthalate esters and the anogenital distance (AGD) as a reproductive endpoint in human male newborns. Spot urine samples were collected from 111 Japanese pregnant women after obtaining their informed consent. Seven urinary phthalate ester metabolites were determined by high performance liquid chromatography-tandem mass spectrometry. Urinary isoflavones concentrations were measured as possible covariates because their oestrogenicities and high exposure levels among Japanese have the potential to affect male genital development. Birth outcomes and AGD, the distance from the centre of the anus to external genitalia, were measured for their male newborns. In a multiple regression model, the log-transformed mono-2-ethylhexyl phthalate concentration (specific gravity-corrected) was negatively significant, and maternal smoking status was positively significant, in explaining anogenital index (AGI) when potential covariates were controlled for. Urinary isoflavones did not significantly contribute to AGI in any models. Our results suggest that prenatal exposure to di(2-ethylhexyl) phthalate affects reproductive development in human males.

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.

Daily urinary excretion of bisphenol A

ObjectivesConcerns 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 β-glucuronidase), as well as determining intra-individual variation in BPA excretion.MethodsTwenty-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.ResultsA 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).ConclusionsMeasuring 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.

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.

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. Environ Toxicol Chem 2013;32:2009–2017.