Hexabromocyclododecanes (HBCDs) in the environment and humans: a review

Hexabromocyclododecanes (HBCDs) are brominated aliphatic cyclic hydrocarbons used as flame retardants in thermal insulation building materials, upholstery textiles, and electronics. As a result of their widespread use and their physical and chemical properties, HBCDs are now ubiquitous contaminants in the environment and humans. This review summarizes HBCD concentrations in several environmental compartments and analyzes these data in terms of point sources versus diffuse sources, biomagnification potential, stereoisomer profiles, time trends, and global distribution. Generally, higher concentrations were measured in samples (air, sediment, and fish) collected near point sources (plants producing or processing HBCDs), while lower concentrations were recorded in samples from locations with no obvious sources of HBCDs. High concentrations were measured in top predators, such as marine mammals and birds of prey (up to 9600 and 19 200 ng/g lipid weight, respectively), suggesting a biomagnification potential for HBCDs. Relatively low HBCD concentrations were reported in the few human studies conducted to date (median values varied between 0.35 and 1.1 ng/g lipid weight). HBCD levels in biota are increasing slowly and seem to reflect the local market demand. One important observation is the shiftfrom the high percentage of the gamma-HBCD stereoisomer in the technical products to a dominance of the alpha-HBCD stereoisomer in biological samples. A combination of factors such as variations in solubility, partitioning behavior, uptake, and, possibly, selective metabolism of individual isomers may explain the observed changes in stereoisomer patterns. Recommendations for further work include research on how HBCDs are transferred from products into the environment upon production, use, and disposal. Time trends need to be analyzed more in detail, including HBCD stereoisomers, and more data on terrestrial organisms are needed, especially for humans. Whenever possible, HBCDs should be analyzed as individual stereoisomers in order to address their fate and effects.     

A new enzymatically produced 1-lactulose: A pilot study to test the bifidogenic effects

In a novel pilot plant scale process, lactulose was synthesized enzymatically, operating a maximum batch volume of 170 L. The test product was subjected to a randomized, double-blind, placebo-controlled pilot feeding study. Participants consumed a milk serum drink for 14 days, equalling a daily intake of about 3 g d⁻¹ galactosyl-fructoses. Additionally, the effect of industrially produced lactulose and a placebo drink without lactulose was determined. So far, clinical studies on the prebiotic action of lactulose only focussed on the effects of industrially generated lactulose. The intake of enzymatically synthesized lactulose significantly increased (p = 0.001) faecal bifidobacterial counts, while there was no difference with industrially produced lactulose. Analysis of the compounds showed that the drink with enzymatically synthesized lactulose contained an additional disaccharide, β-1,1-galactosyl-fructose. Presumably, this sugar has a bifidogenic effect and may represent a novel prebiotic.     

Determinants of serum polybrominated diphenyl ether (PBDE) levels among pregnant women in the CHAMACOS cohort

We measured levels of 10 polybrominated diphenyl ether (PBDE) congeners in serum collected during pregnancy and at delivery from 416 pregnant, predominantly immigrant, women living in Monterey County, CA. The most frequently detected congeners were BDE-47, -99, -100, and -153, all components of the penta mixture, detected in >97% of samples. We used multivariable regression models to examine factors associated with exposure to individual PBDE congeners as well as their total summed concentration (ng/g lipid). Prenatal and delivery total PBDE levels were correlated between sampling times (n = 21; Pearson r = 0.99, p < 0.001). In multivariable models, total PBDE levels increased significantly with time residing in the U.S. (p < 0.001) and among women with ≥3 pieces of stuffed furniture in their homes (p < 0.05). Women's total PBDE levels increased 4.0% (95% CI = 2.8, 5.3) for each additional year residing in the U.S., after adjustment for prepregnancy BMI, weight gain during pregnancy, and SES. Having ≥3 pieces of stuffed furniture in the home was associated with a 26.8% (95% CI = 2.0, 57.5) increase in women's serum PBDE levels. Findings suggest PBDE indoor contamination in California homes is contributing to human exposures in a population of recent immigrants.     

Market surveillance for contamination with thermotolerant campylobacters on various categories of chicken meat in Switzerland

From April 2009 to April 2010, 1,132 samples of different types of chicken meat were tested qualitatively and quantitatively for thermotolerant campylobacters. Samples were recovered at retail in shops from the entire territory of Switzerland and comprised imported meat and meat from domestic production. The meat categories covered by the study were refrigerated and frozen meat, meat with and without skin, and meat preparations. Overall, 38.4% of the samples were positive, and in 27.8%, Campylobacter bacteria could be quantified. Counts ranged from ≥10 to <10(4) CFU/g with a maximum value of 8 × 10(3) CFU/g in a sample of refrigerated chicken meat with skin. The contamination frequencies were 45.2% in meat with skin, 40.8% in meat without skin, and 27.4% in meat preparations. Refrigerated meat was contaminated with Campylobacter bacteria more often than frozen meat (53.9 versus 20.0%). The study also showed considerable differences between the contamination rates found for samples from different large retail chains. In 2010, a further study with 120 samples of refrigerated and sliced chicken meat and fresh chicken liver was carried out in order to test a possible seasonal variation of the occurrence of Campylobacter bacteria. The contamination frequency of sliced meat increased from 10.0% in the period from February to March to 36.7% during July to August. In both sampling periods, the counts remained in the range of ≥10 to <100 CFU/g with a maximum value of 30 CFU/g. For chicken liver, a 10.0% contamination rate was observed in the period from December to January, which rose to 100% in the period from August to October. Contrary to the results for sliced meat, not only did the frequency of contamination increase but so did the Campylobacter counts, with the highest recorded value being 2.2 × 10(4) CFU/g.     

Evaluation of colour properties and chemical quality parameters of cactus juices

The chemical composition and visual appearance of cactus fruits from the genera Opuntia and Hylocereus were investigated. Colour properties were assessed in solutions with pH ranging from 1 to 8 and expressed as chroma, hue and colour shade. Between pH 3 and 7, all samples were stable as indicated by hue and chroma values. The colour shade of the red juice of Opuntia ficus-indica cv. 'Rossa' was in the range of red beet preparations hitherto most commonly used for colouring low-acid food commodities. Hylocereus was characterized by purplish hues, whereas the juice from O. ficus-indica cv. 'Gialla' displayed a yellow tonality. An improved spectrophotometric method for pigment quantification was proposed. Betacyanin contents were 525.3, 73.9 and 1.3 mg/l in juices from Hylocereus polyrhizus, Opuntia ficus-indica cv. 'Rossa' and O. ficus-indica cv. 'Gialla', whereas betaxanthins amounted to 48.3, 36.4 and 5.3 mg/l in O. ficus-indica cv. 'Gialla', O. ficus-indica cv. 'Rossa', and H. polyrhizus, respectively. Although the colourless fruits from O. ficus-indica cv. 'Bianca' and H. undatus could not be considered as a colour source, selected quality parameters were also investigated with respect to their nutritional value. To the best of our knowledge, this is the first report about the chemical quality parameters of H. polyrhizus and H. undatus.     

Catalyzed oxidation of arsenic(III) by hydrogen peroxide on the surface of ferrihydrite: an in situ ATR FTIR study

Knowledge of arsenic redox kinetics is crucial for understanding the impact and fate of As in the environment and for optimizing As removal from drinking water. Rapid oxidation of As(III) adsorbed to ferrihydrite (FH) in the presence of hydrogen peroxide (H2O2) might be expected for two reasons. First, the adsorbed As(III) is assumed to be oxidized more readily than the undissociated species in solution. Second, catalyzed decomposition of H2O2 on the FH surface might also lead to As(III) oxidation. Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy was used to monitor the oxidation of adsorbed As(III) on the FH surface in situ. No As(III) oxidation within minutes to hours was observed prior to H2O2 addition. Initial pseudo-first-order oxidation rate coefficients for adsorbed As(III), determined at H2O2 concentrations between 8.4 microM and 8.4 mM and pH values from 4 to 8, increased with the H2O2 concentration according to the equation log k(ox) (min(-1)) = 0.17 + 0.50 log [H2O] (mol/L), n = 21, r2 = 0.87. Only a weak pH dependence of log k(ox) was observed (approximately 0.04 logarithm unit increase per pH unit). ATR-FTIR experiments with As(III) adsorbed onto amorphous aluminum hydroxide showed that Fe was necessary to induce As(III) oxidation by catalytic H2O2 decomposition. Supplementary As(III) oxidation experiments in FH suspensions qualitatively confirmed the findings from the in situ ATR-FTIR experiments. Our results indicate that the catalyzed oxidation of As(III) by H2O2 on the surface of iron (hydr)oxides might be a relevant reaction pathway in environmental systems such as surface waters, as well as in engineered systems for As removal from water.     

Regulation of genes encoding proteolytic enzymes during mammary gland development

The mammary gland undergoes extensive tissue remodelling during each lactation cycle. During pregnancy, the epithelial compartment of the gland is vastly expanded (Benaud et al. 1998). At the end of lactation the epithelial cells undergo apoptosis and adipocyte differentiation is induced (Lilla et al. 2002). Ductal and alveolar growth during puberty and pregnancy, and the involution process require the action of proteolytic enzymes (including matrix metalloproteinases, plasminogen and membrane-peptidases) and the corresponding genes are activated during these periods (Benaud et al. 1998; Alexander et al. 2001). Matrix metalloproteinases (MMP) are expressed in several cell types of the mammary gland including stromal fibroblasts (e.g., MMP3, MMP2), epithelial cells (e.g., MMP7 or MMP9), adipocytes (e.g., MMP2) and lymphoid cells (e.g., MMP9) (Crawford et al. 1996; Lund et al. 1996; Wiseman et al. 2003). A number of knock-out mice, which are deficient for individual MMP genes (e.g., MMP2, MMP3) or plasminogen, display alterations to mammary gland structure and impairment of lactation (Lund et al. 1999; Wiseman et al. 2003).     

Occurrence of a nitro metabolite of a defined nonylphenol isomer in soil/sewage sludge mixtures

Uniformly [14C]-ring-labeled 4-(3,5-dimethyl-3-heptyl)phenol (353-nonylphenol) is a highly relevant isomer of the technical nonylphenol mixture. We studied the sorption, desorption, and degradation of the synthesized isomer in an agricultural sandy loam at various soil/sewage sludge ratios. Sorption of 353-nonylphenol was high and differed with the amount of suspended soil in water. log Koc values, which are used to assess the risk of nonylphenol, ranged from 3.80 to 5.75. Desorption was slow and low and resulted in constant concentrations of about 15 ng/L353-nonylphenol in water after several desorption steps. In degradation studies up to 6% of the applied 353-nonylphenol in soil was volatilized; we consider this an important source of nonylphenol in the environment. With increasing amounts of sewage sludge in the soil/sewage sludge mixtures, 353-nonylphenol was stabilized, probably because of the lack of oxygen in sludge aggregates even under oxic conditions in flow-through systems. Unexpectedly, a less-polar metabolite was detected in amounts up to 40% of the applied nonylphenol after 135 days of incubation. This novel metabolite was identified as 4-(3,5-dimethyl-3-heptyl)-2-nitrophenol. This product formation might indicate the existence of novel metabolic pathways of nonylphenol in the environment.     

Smart 概念——苹果加工的全套解决方案

酶制剂在苹果汁生产中的作用 在苹果原料的成熟和储存过程中,苹果细胞壁的多糖也在逐步演变,苹果会慢慢变软,一些多糖会部分溶解.这些多糖都具备高度的持水性,能将果汁保持在果浆中,导致可榨性降低,出汁率下降.为了确保苹果出汁率达到最佳水平.必须在榨汁阶段加入果浆酶.