Persistence of organic contaminants in soils from a sewage sludge amended field experiment

Digested sludge was applied to plowed arable and pasture grassland plots and losses of specific volatile organic compounds (VOCs), polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and chlorophenols (CPs) monitored over 260 d. Sludge addition increased soil concentrations of all compounds in the plowed plot. VOCs, PCBs, and CPs concentrations declined to control plot values within 128 d of sludge amendment. Volatilization and biodegradation were considered important loss processes for these compounds. However, PCDD/F and of non-o-PCB 77 concentrations did not change consistently and remained elevated above control plot concentrations throughout the monitoring period. At Day 260 410 ± 53 ng PCDD kg–1 and 250 ± 10 ng PCDF kg–1 was detected in the sludged plot compared to 68 ± 9 ng PCDD kg–1 and 170 ± 7 ng PCDF kg–1 in the control plot. Data from the pasture plot has highly variable and differences between most contaminant concentrations in the sludged and control plots were insignificant. This was attributed to adherence of much of the applied sludge to vegetation rather than direct application to the soil surface and has important implications for elevated dietry intake of certain persistent organic compounds such as the PCDD/Fs. Further research is needed to evaluate the importance of sludge adherence to vegetation for human exposure to a range of contaminants detected in sludge. Contaminant movement to depth (20 cm) was not detected within 260 d for compounds monitored (VOCs and PCDD/Fs)

Exploring the balance between sources, deposition and the environmental burden of PCDD/Fs in the UK terrestrial environment: an aid to identifying uncertainties and research needs.

The United Kingdom is used as a study area in which to examine (i) the relationship between primary and potential secondary emissions of PCDD/Fs; (ii) the balance between atmospheric emissions and deposition; and (iii) the contemporary environmental burden of PCDD/Fs and possible historical input profiles. This critical review exercise is seen as an important aid to identifying gaps in knowledge and research needs and directing a scientifically sound strategy for PCDD/F risk reduction. The paper focuses on two key compartments, air and soil, as these play an important role in the movement and storage of PCDD/Fs. The terrestrial agricultural food chain supplies the majority of human exposure to PCDD/Fs via the pathway air−deposition−crop/pasture/soil−grazing animals−meat/dairy products−human diet. Primary emissions of PCDD/Fs to the atmosphere are expected to decline in the future following the implementation of new legislative controls. This should be reflected by a further decline in ambient air concentrations, as our calculations indicate that primary emissions are currently the main PCDD/F sources to air. The soil burden will take much longer to decline, due to the extreme persistence of these compounds in this environmental matrix. The paper highlights uncertainties and future research needs concerning the environmental sources, fate, and behavior of this group of compounds

" Interpréter le De signis de Nicétas Chôniatès, ou le mirage de l'historien "

International audienc

Polychlorinated biphenyls (PCBs) in the British environment: Sinks, sources and temporal trends.

This paper estimates the present UK environmental loading of polychlorinated biphenyls (PCBs). Of the estimated ≈ 40 000 t ΣPCB sold in the UK since 1954, only an estimated 1% (400 t) are now present in the UK environment. Comparisons of estimated production and current environmental loadings of congeners 28, 52, 101, 138, 153 and 180 suggest that PCB persistence broadly increases with increasing chlorination. Those PCBs that are not now present in the UK environment are considered to have been destroyed—by natural or anthropogenic mechanisms, to be still in use, to reside in landfills or to have undergone atmospheric and/or pelagic transport from the UK. The dramatic fall in PCB levels in archived UK soils and vegetation between the mid-1960s and the present is evidence that the latter mechanism is the most important and that a significant proportion of PCBs released into the UK environment in the 1960s have subsequently undergone environmental transport away from the UK. The bulk (93·1%) of the estimated contemporary UK environmental burden of ΣPCBs is associated with soils, with the rest found in seawater (3·5%) and marine sediments (2·1%). Freshware sediments, vegetation, humans and sewage sludge combined account for 1·4% of the present burden, whilst PCB loadings in air and freshwater are insignificant. Although consideration of individual congeners does not reveal any major deviations from the relative partitioning of Σ PCBs, the importance of sinks other than soils is enhanced for individual congeners, particularly 138 and 180. In particular, around 2% of the total UK burden of congener 180 is present in humans, implying that biodata as a whole may constitute an important sink for the higher chlorinated congeners. The contemporary flux of ΣPCBs to the UK surface is estimated at 19 t yr−1, compared with an estimated annual flux to the atmosphere of 44–46 t. This implies that the major sources of PCBs to the UK atmosphere have been identified and that there is currently a net loss of these compounds from the UK. These sources are: volatilisation from soils (88·1%), leaks from large capacitors (8·5%), the production of refuse-derived fuel (RDF) (2·2%), leaks from transformers (0·6%), the recovery of contaminated scrap metal (0·5%) and volatilisation from sewage sludge-amended land (0·2%). Interestingly, whilst large excesses of estimated annual fluxes to the atmosphere over deposition fluxes for individual congeners exist for congeners 28, 52 and 101, estimates of fluxes in both directions across the soil-atmosphere interface agree closely for congeners 138, 153 and 180. This suggests that lower chlorinated congeners are more susceptible to both long-range environmental transport beyond the UK and to atmospheric degradation. Retrospective analysis of dated sediment cores, vegetation and soils indicates that environmental transport from North America and continental Europe introduced PCBs into the British environment well before the onset of their commercial production in the UK in 1954. Since that time, the input of PCBs to the UK environment has essentially reflected temporal trends in UK use. After peaking in the 1960s they declined rapidly through the 1970s following restrictions on PCB use. Recent evidence, however, is that the rate of decrease has diminished and that further significant reductions in fresh environmental input will take some time to occur. Such reductions will be especially slow for humans and other biota with long life-spans. This stems partly from cross-generational transfer from parents to offspring and also because the persistence of PCBs in biota means that present body burdens will reflect past as well as current exposure

Patient-reported outcomes of immediate implant-based breast reconstruction with and without biological or synthetic mesh

Background: biological and synthetic meshes may improve the outcomes of immediate implant-based breast reconstruction (IBBR) by facilitating single-stage procedures and improving cosmesis. Supporting evidence is, however, limited. The aim of this study was to explore the impact of biological and synthetic mesh on patient-reported outcomes (PROs) of IBBR 18 months after surgery.Methods: consecutive women undergoing immediate IBBR between February 2014 and June 2016 were recruited to the study. Demographic, operative, oncological and 3-month complication data were collected, and patients received validated BREAST-Q questionnaires at 18 months. The impact of different IBBR techniques on PROs were explored using mixed-effects regression models adjusted for clinically relevant confounders, and including a random effect to account for clustering by centre.Results: a total of 1470 participants consented to receive the questionnaire and 891 completed it. Of these, 67 women underwent two-stage submuscular reconstructions. Some 764 patients had a submuscular reconstruction with biological mesh (495 women), synthetic mesh (95) or dermal sling (174). Fourteen patients had a prepectoral reconstruction. Compared with two-stage submuscular reconstructions, no significant differences in PROs were seen in biological or synthetic mesh-assisted or dermal sling procedures. However, patients undergoing prepectoral IBBR reported better satisfaction with breasts (adjusted mean difference +6.63, 95 per cent c.i. 1.65 to11.61; P = 0.009). PROs were similar to those in the National Mastectomy and Breast Reconstruction Audit 2008-2009 cohort, which included two-stage submuscular procedures only.Conclusion: this study found no difference in PROs of subpectoral IBBR with or without biological or synthetic mesh, but provides early data to suggest improved satisfaction with breasts following prepectoral reconstruction. Robust evaluation is required before this approach can be adopted as standard practice.</p