Risk Assessment of Bioaccumulation Substances. Part II: Description of a Model Framework

This report provides a proposal for a framework for risk assessment of bioaccumulative substances, either from produced water discharges or present as background contamination. The proposed framework is such that it is compatible to the current EIF risk assessment models that are used in the Norwegian offshore oil and gas industry. The risk assessment approach selected for this framework is based on the use of critical body residues (CBR); i.e., body-tissue concentrations above which adverse effects are expected. A three-tiered risk assessment approach is distinguished: tier 1 for worst-case screening purposes; tier 2 based on probabilistic risk assessment using species sensitivity distributions and tier 3 focusing on population modelling for specific species. The latter tier is, because of its specific characteristics, not elaborated in detail. It is proposed to use a food-chain accumulation model to translate species sensitivity thresholds on the basis of CBR into external threshold concentrations, those external thresholds could then be used to either derive an ecosystem PNEC (tier I) or Species Sensitivity Distribution (tier II). This would provide a pragmatic approach to risk assessment of bioaccumulative substances in the context of the EIF modelling framework. Finally, an outline is provided for a research project in which the a risk assessment model for bioaccumulative substances is developed. This model will then be applied to two cases for purposes of demonstration and evaluation. An indication of workload and planning is provided

Polymer induced condensation of dna supercoils

Macromolecular crowding is thought to be a significant factor driving DNA condensation in prokaryotic cells. Whereas DNA in prokaryotes is supercoiled, studies on crowding-induced DNA condensation have so far focused on linear DNA. Here we compare DNA condensation by poly(ethylene oxide) for supercoiled and linearized pUC18 plasmid DNA. It is found that supercoiling has only a limited influence on the critical amount of PEO needed to condense plasmid DNA. In order to pack DNA supercoils in condensates, it seems inevitable that they must be deformed in one way or another, to facilitate dense packing of DNA. Analytical estimates and Monte Carlo simulations indicate that packing of DNA supercoils in condensates is most likely facilitated by a decrease of the superhelical diameter rather than by unwinding of the supercoil

Development and adaptation to resection of infant rat gut

Infants with malrotation of the gut easily develop midgut volvuluse If this volvulus is not treated immediately, ischemic necrosis of the small bowel may develop rapidly. The treatment of these children requires extensive small bowel resection. Infrequently, children are born with multiple jejunal or ileal atresias or with an 'apple peel' type of small bowel atresia. Both after massive small bowl resections and in severe atresias, the child is left with a very short length of bowel and great difficulties to thrive. Fortunately, with time both functional an::l morphological adaptation of the remnant small bowel occurs. In the neonatal period it is not clear whether growth of the small bowel after a massive resection is part of normal growth or ~hether it is due to, or may be enhanced by, adaptational responses. Neonates, especially in the recovery stage from intestinal surgery, often have to be fed parenterally, or later, with artificial milk formulas. It is known from experiments in adult animals, that oral feeding stimulates adaptation of small intestine after resections. In the newborn, colostrum seems to provide a special stimulus for gut growth, as has been suggested by animal studies and by experiments in vitro. Therefore, we thought it could be important to examine the effects of colostrum, of breast milk produced later in lactation, and of a commercial milk formula on normal development and on adaptation to resection of the intestine. l'le also studied the effect of the presence of food in the small bowel on development and adaptation. Some of the components of breast milk which are not present in artificial formulas are macromolecules, especially y-globulins, and viable rnacrophages. Breast milk provides passive immunity in some species and other host resistance factors, protecting the suckling in most species. Furthermore it has a regulatory effect on bacterial colonization in the bowel. Since necrotizing enterocolitis occurs with much lower frequency in breastfed human neonates, breastmilk may play a role in the prevention of this disease by maintaining the normal mucosal barrier to bacteria and harmful macromolecules. Surgery of the small bowel also influences the uptake and transport of macromolecules. In some studies increased transport was noted due to the loss of mucosal integrity. From studies on adaptation after resection it can be concluded, however, that after surgery premature cessation of transport of macromolecules may occur. Since uncertainty still exists about the effects of surgery on macromolecular transport, this was also studied

Manual to proposed Dutch implementation of OSPAR's risk-based approach to the management of produced water discharges

This manual is intended to assist operators on the Dutch Continental Shelf in the application of the Dutch implementation of the risk-based approach (RBA). In essence all oil and gas platforms on the Dutch Continental Shelf (DCS) have to go through the risk management cycle at least once, where the pre-screening determines in which order the platforms enter the cycle. The risk management cycle follows all steps required for the RBA, which are all individually addressed in the following chapters: chapter 3 (sampling); chapter 4 (whole effluent toxicity risk assessment, including ecotoxicological testing of the effluent and risk characterisation); chapter 5 (substance-based risk assessment, including chemical analysis and risk characterisation); chapter 6 (measures) and chapter 7 (reporting)

Critical loads and excess loads of cadmium, copper and lead for European forest soils

Recently, concern has arisen about the impact of the dispersion of heavy metals in Europe. Therefore, a study (ESQUAD) was initiated to assess critical loads and steady-state concentrations of cadmium, copper and lead for European forest soils. The calculation methods used strongly resemble those used to compute critical loads for acidifying compounds. Results show that the computed critical loads and associated excess loads for forest soils strongly depend on the threshold values chosen and on the soil phase (adsorbed/dissolved) considered. Further research is needed to improve input data and the modelling of heavy metal adsorption

Validation and application of soil acidification models at local, national and European scale; a compilation of articles on the models NuCSAM, ReSAM and SMART

An overview is given of three dynamic soil acidification models for application on different spatial scales. NUCSAM, the model for the local scale, was validated on data from two intensively monitored research sites. Results of annual average soil solution concentrations and fluxes calculated with the validated NUCSAM model agreed well with those of the national-scale model RESAM and to a lesser extent with those of the European-scale model SMART. Various deposition scenarios for SOx, NOx and NHx on soils were evaluated with the three acidification models

Critical loads of copper, nickel, zinc, arsenic, chromium and selenium for terrestrial ecosystems at a European scale; a preliminary assessment

This reports provides a preliminary assessment of critical loads of Cu,Ni,Zn,Cr, As and Se for Europe. Critical loads were computed according to existing methods, for forest soils and agricultural soils. Critical loads were assessed aiming at groundwater protection and for avoiding ecotoxilogical effects on soil organisms. Methods and input data for the models are described as well as critical limits used. Maps are provided showing the geographical distribution of 5 percentile critical loads for Europe for each metal and effect seperately. Results of the study are discussed in terms of geographical patterns and critical load ranges, and some indication of uncertainties and possible improvements of the applied methods and data is provided

Hereditary Breast-Ovarian Cancer Team of the University Medical Centre Groningen (UMCG):a Report

Female carriers of a germline BRCA1 or BRCA2 mutation have a cumulative lifetime ovarian cancer risk of 39-54 % or 11-23%, respectively [1, 2]. Preventive health strategies for these women include gynaecological screening aiming at early cancer detection and prophylactic salpingo-ophorectomy aiming at cancer risk reduction. However, it is becoming increasingly clear that (bi) annual gynaecological screening by transvaginal ultrasonography and serum CA125 estimation in women at increased risk of ovarian cancer is ineffective in detecting presymptomatic ovarian cancer [4]. In a recent publication a positive predictive value of 17 % and a sensitivity of less than 50 % were found for screening for ovarian cancer in a high-risk population [3]. Preventive bilateral salpingo-oophorectomy (BSO) reduces ovaria