Ow Data Research Articles

Why data about people are so hard to govern

AbstractHow data on individuals are gathered, analyzed, and stored remains largely ungoverned at both domestic and global levels. We address the unique governance problem posed by digital data to provide a framework for understanding why data governance remains elusive. Data are easily transferable and replicable, making them a useful tool. But this characteristic creates massive governance problems for all of us who want to have some agency and choice over how (or if) our data are collected and used. Moreover, data are co‐created: individuals are the object from which data are culled by an interested party. Yet, any data point has a marginal value of close to zero and thus individuals have little bargaining power when it comes to negotiating with data collectors. Relatedly, data follow the rule of winner take all—the parties that have the most can leverage that data for greater accuracy and utility, leading to natural oligopolies. Finally, data's value lies in combination with proprietary algorithms that analyze and predict the patterns. Given these characteristics, private governance solutions are ineffective. Public solutions will also likely be insufficient. The imbalance in market power between platforms that collect data and individuals will be reproduced in the political sphere. We conclude that some form of collective data governance is required. We examine the challenges to the data governance by looking a public effort, the EU's General Data Protection Regulation, a private effort, Apple's “privacy nutrition labels” in their App Store, and a collective effort, the First Nations Information Governance Centre in Canada.

Learned Discourses: Timely Scientific Opinions.

The fate of a chemical in the environment is primarily controlled by the physico-chemical properties of the substance, prevailing environmental conditions, and patterns of use (Mackay et al. 1997). Thus, accurate determination of physico-chemical properties is critical to the formulation of valid environmental models and assessments (Bennett et al. 2001). As litigation becomes an increasingly common aspect of environmental science, such studies may be challenged and even refuted. Recent legislation in the United States mandates that federal agencies must ensure the quality of data upon which regulatory action and policy decisions are founded (Reichhardt 2002). Some observers have suggested that because this legislation provides for unprecedented scrutiny of agency data quality, regulatory agencies might face a marked increase in the number of legal challenges. Two of the most important physico-chemical properties relating to the environmental behavior of hydrophobic organic compounds are aqueous solubility (S w ) and the octanol-water partition coefficient (K ow ). Much of the interest in these properties comes from the fact that they can be used to estimate or predict other properties of more immediate environmental and ecotoxicological interest. For this reason, a primary focus of research in the last 20 years has been development of linear regression models in which S w and K ow (or more accurately, their logarithms) are correlated with parameters such as the organic carbon-normalized partition coefficient, bioconcentration and bioaccumulation factors, and indices of biodegradability or toxicity. These, in turn, can be incorporated into models that attempt to characterize the equilibrium distribution and transport rates of organic contaminants among environmental media or to predict impacts on biota. The predictions of such multimedia models have taken on greater immediacy with the recognition that certain persistent organic pollutants, such as DDT and DDE, are globally distributed and may be exerting adverse biological effects far from their original source areas (Wania and Mackay 1996). Our interest in the K ow and S w values of DDT and DDE arose in the context of research we were conducting on the geochemical fate of these compounds in sediments of the Palos Verdes Shelf, California. We expected that studies reporting S w and K ow values for DDT and DDE would be well documented because DDT has a very long history, and its widespread application and biological effects are well known. Results of our initial literature survey, however, were unsatisfactory due to a large spread in data values. We decided to undertake an exhaustive review to identify all measured and estimated values of S w and K ow for these compounds. It soon became apparent that a number of serious problems severely limited use of the database and that our initial expectations had been naive. A complete description of the study discussed here can be found in a USGS report (Pontolillo and Eganhouse 2001) available in PDF format on the web (http://pubs.water.usgs.gov/ wri01-4201/). We examined more than 700 publications including databases, handbooks, review articles, and bibliographies for data, methodological details, and pertinent literature citations. The initial survey was augmented by computerized searches of the scientific literature using the Chemical Abstracts Search Service Index (CASSI) database and the World Wide Web using a variety of Internet searchengines. Several hundred potential articles were generated in this fashion. Each article was retrieved and scrutinized, and additional relevant leads were identified from the reference lists. The search progressed until no further leads could be identified (approximately 2 years). Two problems are evident with the available database: egregious errors in reporting data and references, and poor data quality and/or inadequately documented procedures. The published literature is characterized by a preponderance of unnecessary data duplication. Numerous data and citation errors are also present. The percentage of original S w and K ow data for DDT

Platinum(IV)-nitroxyl complexes as possible candidates to circumvent cisplatin resistance in RT112 bladder cancer cells

The therapeutic efficacy of the anticancer drug cisplatin is limited by the development of resistance. We therefore investigated newly synthesized platinum-nitroxyl complexes (PNCs) for their potential to circumvent cisplatin resistance. The complexes used were PNCs with bivalent cis-PtII(R·NH2)(NH3)Cl2 and cis-PtII(DAPO)Ox and four-valent platinum cis,trans,cis-PtIV(R·NH2)(NH3)(OR)2Cl2 and cis,trans,cis-PtIV(DAPO)(OR)2Ox, where R· are TEMPO or proxyl nitroxyl radicals, DAPO is trans-3,4-diamino-2,2,6,6-tetramethylpiperidine-1-oxyl, and OR and Ox are carboxylato and oxalato ligands, respectively. The complexes were characterized by spectroscopic methods, HPLC, log P ow data and elemental analysis. We studied intracellular platinum accumulation, DNA platination and cytotoxicity upon treatment with the PNCs in a model system of the bladder cancer cell line RT112 and its cisplatin-resistant subline RT112-CP. Platinum accumulation and DNA platination were similar in RT112 and RT112-CP cells for both bivalent and four-valent PNCs, in contrast to cisplatin for which a reduction in intracellular accumulation and DNA platination was observed in the resistant subline. The PNCs were found to platinate DNA in relation to the length of their axial RO-ligands. Furthermore, the PNCs were increasingly toxic in relation to the elongation of their axial RO-ligands, with similar toxicities in RT112 and its cisplatin-resistant subline. Using a cell-free assay, we observed induction of oxidative DNA damage by cisplatin but not PNCs suggesting that cisplatin exerts its toxic action by platination and oxidative DNA damage, while cells treated with PNCs are protected against oxidatively induced lesions. Altogether, our study suggests that PNCs may provide a more effective treatment for tumors which have developed resistance toward cisplatin.

Estimation of mean annual runoff across southeast Australia by incorporating vegetation types into Budyko-framework

This paper uses the Budyko and Fu models to estimate mean annual runoff in 0.05 degrees grid cells across southeast Australia, and assesses the estimates against observations in 323 catchments. The results show that the Budyko model can provide reasonable estimates of runoff and is suitable for data limited regions. In regions where there are some streamfl ow data available, the calibration of a single parameter in the Fu model gives better runoff estimates than the Budyko model and similar to regionalised rainfall-runoff models. In drier regions, the consideration of different vegetation types in the Fu model can improve the modelling results.

A novel evaluation method for extrapolated retention factor in determination of n-octanol/water partition coefficient of halogenated organic pollutants by reversed-phase high performance liquid chromatography

The retention factor corresponding to pure water in reversed-phase high performance liquid chromatography (RP-HPLC), k w , was commonly obtained by extrapolation of retention factor ( k) in a mixture of organic modifier and water as mobile phase in tedious experiments. In this paper, a relationship between log k w and log k for directly determining k w has been proposed for the first time. With a satisfactory validation, the approach was confirmed to enable easy and accurate evaluation of k w for compounds in question with similar structure to model compounds. Eight PCB congeners with different degree of chlorination were selected as a training set for modeling the log k w − log k correlation on both silica-based C 8 and C 18 stationary phases to evaluate log k w of sample compounds including seven PCB, six PBB and eight PBDE congeners. These eight model PCBs were subsequently combined with seven structure-similar benzene derivatives possessing reliable experimental K ow values as a whole training set for log K ow − log k w regressions on the two stationary phases. Consequently, the evaluated log k w values of sample compounds were used to determine their log K ow by the derived log K ow − log k w models. The log K ow values obtained by these evaluated log k w were well comparable with those obtained by experimental-extrapolated log k w , demonstrating that the proposed method for log k w evaluation in this present study could be an effective means in lipophilicity study of environmental contaminants with numerous congeners. As a result, log K ow data of many PCBs, PBBs and PBDEs could be offered. These contaminants are considered to widely exist in the environment, but there have been no reliable experimental K ow data available yet.

Heat Flow and Hydrologic Characteristics at the AND-1B borehole, ANDRILL McMurdo Ice Shelf Project, Antarctica

The Antarctic Drilling Program (ANDRILL) successfully drilled and cored a borehole, AND-1B, beneath the McMurdo Ice Shelf and into a fl exural moat basin that surrounds Ross Island. Total drilling depth reached 1285 m below seafl oor (mbsf) with 98 percent core recovery for the detailed study of glacier dynamics. With the goal of obtaining complementary information regarding heat fl ow and permeability, which is vital to understanding the nature of marine hydrogeologic systems, a succession of three temperature logs was recorded over a fi veday span to monitor the gradual thermal recovery toward equilibrium conditions. These data were extrapolated to true, undisturbed temperatures, and they defi ne a linear geothermal gradient of 76.7 K/km from the seafl oor to 647 mbsf. Bulk thermal conductivities of the sedimentary rocks were derived from empirical mixing models and density measurements performed on core, and an average value of 1.5 W/mK ± 10 percent was determined. The corresponding estimate of heat fl ow at this site is 115 mW/m 2 . This value is relatively high but is consistent with other elevated heat-fl ow data associated with the Erebus Volcanic Province. Information regarding the origin and frequency of pathways for subsurface fl uid fl ow is gleaned from drillers’ records, complementary geophysical logs, and core descriptions. Only two prominent permeable zones are identifi ed and these correspond to two markedly different features within the rift basin; one is a distinct lithostratigraphic subunit consisting of a thin lava fl ow and the other is a heavily fractured interval within a single thick subunit.

QSAR Models for Predicting in Vivo Aquatic Toxicity of Chlorinated Alkanes to Fish

Quantitative structure-activity relationship (QSAR) models are expected to play a crucial role in reducing the number of animals to be used for toxicity testing resulting from the adoption of the new European Union chemical control system called Registration, Evaluation, and Authorization of Chemicals (REACH). The objective of the present study was to generate in vitro acute toxicity data that could be used to develop a QSAR model to describe acute in vivo toxicity of chlorinated alkanes. Cytotoxicity of a series of chlorinated alkanes to Chinese hamster ovary (CHO) cells was observed at concentrations similar to those that have been shown previously to be toxic to fish. Strong correlations exist between the acute in vitro toxicity of the chlorinated alkanes and (i) hydrophobicity [modeled by the calculated log K ow (octanol-water partition coefficient); r (2) = 0.883 and r int (2) = 0.854] and (ii) in vivo acute toxicity to fish ( r (2) = 0.758). A QSAR model has been developed to predict in vivo acute toxicity to fish, based on the in vitro data and even on in silico log K ow data only. The developed QSAR model is applicable to chlorinated alkanes with up to 10 carbon atoms, up to eight chlorine atoms, and log K ow values lying within the range from 1.71 to 5.70. Out of the 100204 compounds on the European Inventory of Existing Chemicals (EINECS), our QSAR model covers 77 (0.1%) of them. Our findings demonstrate that in vitro experiments and even in silico calculations can replace animal experiments in the prediction of the acute toxicity of chlorinated alkanes.

Determination of n-octanol/water partition and membrane binding of cationic porphyrins

Porphyrin and their derivatives are being systematically studied as photosensitizers for photodynamic therapy. The ability to predict their membrane partition properties is of key importance to unveil their in vivo activity and applications. Several n-octanol/water partition coefficients (log P OW) of porphyrin derivatives have been reported in the literature but large discrepancies have been observed. Reproducible and reliable log P OW data for a series of 20 cationic meso-phenyl(pyridyl)porphyrin derivatives were determined by correlating log P OW with the partition coefficients measured in a more adequate n-butanol/water system. Linear correlations as a function of the number of positively charged groups bound to the periphery of the porphyrin rings were found within each series. A significant effect of the stereochemistry and nature of the positively charged substituents was also observed, but diminished steadily converging to a similar value in the mono-substituted derivatives. Binding constants to liposomes were shown to be proportional to log P OW, except for the cis-isomers of doubly charged porphyrins. The cis-isomer presented smaller log P OW and higher membrane affinity. The effect was explained based on the amphiphilic nature of the cis-porphyrin.

Examining the Effect of Flow Reversal on Seven-Hole Probe Measurements

Multihole pressure probes are frequently used to gather e ow data, sometimes in highly three-dimensional e ow. If the e ow is reversed, no method currently exists for determining whether the multihole probe is facing the right direction for data acquisition, and that the e ow is as such. A seven-hole probe is rotated in yaw by 360 deg, and rules are formulated to determine if a seven-hole probe is in a reversed e ow. The current study allows seven-hole probes to be used for gathering data in steady reversed e ows and gives an indication whether a pressure probe is insufe cient for the measurement instrument, as in the case of highly recirculating unsteady turbulent e ows. An application of the technique thus developed is also given.

Comparison between phase-velocity cine magnetic resonance imaging and invasive oximetry for quantification of atrial shunts

Measurement of the pulmonary-to-systemic blood fl ow ratio (Qp/Qs) in patients with congenital heart disease and shunting lesions may be useful for determining the need for intervention or assessing outcome postprocedure. Frequently used methods to calculate Qp/Qs, such as invasive oximetry, fi rst-pass radionuclide angiography, and Doppler echocardiography have limitations. 1 Phase-velocity cine magnetic resonance imaging (PVC MRI) is a noninvasive technique to measure blood fl ow that has been demonstrated to be accurate in vitro and in vivo. 2– 6 We have previously reported that subjects without a shunt (n 20) had a mean Qp/Qs of 0.99 0.10 by PVC MRI. 3 The aim of this study was to prospectively evaluate the accuracy, reproducibility, and interobserver variability of PVC MRI measurements of Qp/Qs in subjects with a known shunt. Oximetry at catheterization was selected for comparison because this remains the most widely accepted clinical standard.  The following criteria were included for entry into this study: (1) diagnosis of either a secundum atrial septal defect or patent foramen ovale, (2) planned cardiac catheterization for device closure of an interatrial communication, (3) anticipated ability to undergo a 30-minute MRI examination without the need for sedation (typically age 7 years). Patients referred for percutaneous device closure of an atrial septal defect or patent foramen ovale were chosen as a subject pool for this investigation because they were already scheduled for cardiac catheterization, and they were more likely to be old enough to undergo MRI without the need for sedation than patients with other shunting lesions. The study was approved by the Committee on Clinical Investigation at Children’s Hospital Boston, and informed, written consent was obtained from all participants or their legal guardian. Subjects underwent MRI to quantify fl ow in the main pulmonary artery (Qp) and ascending aorta (Qs), with 2 separate measurements acquired at each location. In all subjects, all PVC MRI fl ow data were analyzed by 2 operators (AP and BT-G) blinded to each other’s results to determine interobserver variability. MRI studies were performed using a 1.5-Tesla whole-body scanner (Signa LX, General Electric, Milwaukee, Wisconsin) with a torso phased-array radiofrequency receiver coil. Through-plane PVC MRI was performed using a commercially available conventional pulse sequence (Cine PC, General Electric) with retrospective electrocardiographic gating, no respiratory gating, and the following acquisition parameters: echo time 6 to 7 ms, repetition time 18 to 20 ms, fl ip angle 15°, fi eld-of-view 240 to 360 mm, matrix 256 128, slice thickness 6 mm, signal averages 2, and velocity encoding value 150 cm/s for the aorta and 200 cm/s for the pulmonary artery. Imaging time for each measurement was 2.3 to 4.2 minutes depending on heart rate. PVC MRI data were analyzed off-line on a computer workstation (Advantage Windows 4.0, General Electric) equipped with commercially available fl ow analysis software (Flow, MEDIS, Leiden, The Netherlands) including automated vessel border detection. The underlying principles and analysis techniques for PVC MRI have been previously de

Numerical Investigation of Transonic Resonance with a Convergent-Divergent Nozzle

At pressure ratios lower than the design value, convergent ‐divergent nozzles often undergo a e ow resonance accompaniedbytheemissionofacoustictones.Thephenomenon,drivenbytheunsteadyshockwithinthedivergent section of the nozzle, has been studied experimentally previously. The space ‐time conservation element solution element method is employed to numerically investigate the phenomenon. The computations are performed for a given nozzle geometry forseveral different pressure ratios. Sustained limit-cycleoscillations are encountered in all cases. The oscillation frequencies and their variation with pressure ratio, including a stage jump, agree well with the experimental results. The unsteady e ow data cone rm that stage 1 of the resonance (fundamental) involves a one-quarter standing wave, whereas stage 2 (third harmonic ) involves a three-quarter standing wave within the divergent section of the nozzle. Details of the shock motion, the e ow, and the near acoustic e eld are documented for one case each of stages 1 and 2. I. Introduction T HIS paper is concerned with an aeroacoustic resonance often encountered with convergent‐ divergent nozzles when run near transonic conditions. The resonance is usually accompanied by the emission of intense acoustic tones. Whereas a casual observer may easily confuse it with the well-known screech tone, it has been shown to be different in character as well as origin. The frequency of the tone increases with increasing plenum pressure. The frequency variation may involve a staging behavior, that is, an abrupt jump in frequency. Whereas odd harmonic stages take place at lower pressures, the fundamental takes place over a wide rangeof higher pressures. Depending on nozzle geometry, the fundamental has been found to persist to pressure ratios as high as 5. The phenomenon has been identie ed and studied experimentally by Zaman etal. 1 For a discussion of background, technological relevance, and pertinent past work from the literature, see Ref. 1. A discussion of numerical works from the literature apparently capturing the same phenomenon, and the implication of those results, will be deferred to the discussion in Sec. V. During the course of the experimental study a numerical study was initiated to complement the investigation. The space‐ time conservation-element and solution-element (CE/SE) method, to be elaborated shortly, was employed because of its past success with e ows involving shocks and acoustic waves. 2 The calculations were e rst performed for a nozzle geometry and pressure ratio that corresponded to an experimental test condition. The result was encouraging in that the e ow not only exhibited a quasi periodicity, but the frequency was also in agreement with the experimental result. Subsequent calculations at two other pressures captured the right trend in the frequency variation as well as the stage jump. These promising results prompted a further study. Thiswas deemedwell-justie ed

Modeling of Three-Dimensional Viscous Compressible Turbomachinery Flows Using Unstructured Hybrid Grids

An advanced numerical model for the simulation of steady and unsteady viscous compressible e ows for turbomachinery applications is described. The compressible Favre-averaged Navier ‐Stokes equations are used together with a one-equation turbulence model. The e ow domain is discretized using unstructured hybrid grids that can contain a mixture of hexahedral, pentahedral, tetrahedral, and triangular prismatic cells. The e ow equations are discretized using a node-centered e nite volume scheme that relies on representing the mesh using an edge-based data structure. A dual time stepping technique is applied to a point implicit formulation so that time accuracy can be maintained with large Courant ‐Friedrichs‐Lewy numbers. Nonree ecting boundary conditions are applied at the ine ow and oute ow boundaries to prevent any spurious ree ections of the outgoing waves. The model was validated against measured data for two cases. Radial proe les of pressure and temperature rise were determined from the steady e ow analysis of a rig fan blade, and these were found to be in very good agreement with the measured quantities. A rotor/stator interaction was studied next. Detailed comparisons were carried out against measured steady and unsteady e ow data and good agreement was obtained in all cases.

Two-Dimensional Nonadiabatic Injection into a Supersonic Freestream

Turbulence and mean e ow measurements were acquired downstream of a normal, supersonic (Mach 1.6), twodimensional, slot injection into Mach 2.9 e ow (Re/m=16 £ 10 6).An adiabatic (Tti/Tt1 =1.0)and two nonadiabatic injection cases (Tti/Tt1 =1.11andTti/Tt1 =0.93)werestudied.Multiple-overheatcross-e lmanemometryandconventional mean e ow probes, as well as instantaneous schlieren photography, were utilized to study the turbulent mixing layer. The mean e ow data included the pitot, cone-static, and Mach number proe les. The measured turbulence data included Reynolds shear stresses and turbulence intensities (mass e ux and total temperature ). The e ow visualizations highlighted the physical phenomena of the e ow as well as the associated turbulent structure that existed in the mixing layer. The injection and wall temperature were found to have a strong ine uence on the near wall (the bottom-half of the mixing layer relative to the wall ) mean and statistical turbulent e ow properties.

Sorption of chlorinated C 1- and C 2-hydrocarbons and monocyclic aromatic hydrocarbons on sea sediment

The sorption of chlorinated C 1- and C 2-hydrocarbons and monocyclic aromatic hydrocarbons on sea sediment was studied with a miscible displacement technique. Detection was done either by on-line UV-detection or off-line GC-analysis. Equilibrium partitioning coefficients between the salt water phase and the marine sediment were determined for 11 compounds by fitting their breakthrough curves to a local sorption equilibrium model. Based on the obtained partitioning coefficients and on the measurement of the organic carbon content of the sediment, the sorption into the organic carbon fraction was considered. Log K oc data ( K oc = organic carbon-water partitioning coefficient) were calculated. A linear relationship between the log K oc values and the log K ow data ( K ow = octanol-water partitioning coefficient) was found ( r = 0.94, n = 11). However, the sorption was lower than expected from the log K ow data. Finally, the implications of the experimental results for the sorption behaviour of the compounds in the marine environment were evaluated. It was concluded that the sea sediment does not act as an important sink for these anthropogenic compounds.

QSAR modelling of soil sorption. Improvements and systematics of log K OC vs. log K OW correlations

A systematic study was performed to evaluate the quality and reliability of the quantitative relationships between the soil sorption coefficients and the n-octanol/water partition coefficients (log K OC vs. log K OW). A system of QSAR models has been derived which is based on a reliable set of experimental log K OW data (LOGPSTAR data) or reliable estimates calculated with the latest version of the ClogP algorithm. Particular emphasis has been made to clearly define the boundaries for application of developed models as well as the quality of estimates. Thus, for each developed model the application domain is clearly defined through the chemical (structural) domain, substituents domain, and X-variable domain. Finally, the QSAR model with the first-order molecular connectivity indices has been incorporated in the derived system of QSAR models since the soil sorption estimates of the predominantly hydrophobic chemicals based on the log K OW data have large uncertainties, particularly in the log K OW data range from 4 to 7.5.

Modeling octanol/water partition coefficients by molecular topology: chlorinated benzenes and biphenyls

Models based on chemical structure were developed for the accurate predictions of octanol/water partition coefficients (log K ow ) for chlorinated benzenes and biphenyls (PCBs). The molecular connectivity indices and other topological properties, readily available for all chemicals, were used as molecular descriptors. In the modeling process only K ow data measured by the direct slow-stirring method have been used. Derived models account for 99.9% of the variation in the log K ow data, and partition properties are described best by the 0 χ v index

A novel efficient and accurate method to calculate n-octanol/water partition coefficients of highly hydrophobic chemicals

Models based entirely on the chemical structure have been developed for the accurate prediction and evaluation of n-octanol/water partition coefficients (log K ow) of chlorinated benzenes, chlorinated biphenyls (PCBs), polynuclear aromatic hydrocarbons (PAHs), and their derivatives. The molecular connectivity indices and other topological features, which are calculated exclusively on the basis of information readily available about all chemicals, synthesized or hypothetical, were used as molecular descriptors. In all models partition-properties are described best by the valence zero-order molecular connectivity ( 0 x v) index. The models developed enable the K ow data to be predicted within a factor of two or better, the probability being above 95%. Their precision is better than the deviation range of 0.30 log unit that is acceptable for the log K ow data according to the OECD guidelines for testing chemicals. Thus, the developed models can be used as a reliable and inexpensive estimation method for predicting and evaluating K ow data for several classes of important hydrophobic chemicals in line with the requirements of the OECD guidelines.

Modelling N-octanol/water partition coefficients by molecular topology: polycyclic aromatic hydrocarbons and their alkyl derivatives

Models based entirely on the chemical structure have been developed for accurate prediction and evaluation of n-octanol/water partition coefficients (log K ow) of the polycyclic aromatic hydrocarbons (PAHs) and their alkyl derivatives. The molecular connectivity indices and other topological features, which are calculated exclusively on the basis of information readily available about all chemicals, synthesized or hypothetical, were used as molecular descriptors. Derived models account for 98% of the variation in the log K ow data which cover the range of 4 orders of magnitude. In all models PAHs partitioning properties are described best by the 0 h ̧ i v indices whose numerical values are directly proportional to PAHs log K ow. Developed models enable the log K ow data to be predicted within a factor of two, the probability being about 98%. This result is in agreement with the deviation range of 0.30 log units proposed to be acceptable according to the OECD guidelines for log K ow data. Thus, our models can be used as reliable estimation method for predicting PAH K ow data in line with the requirements of the OECD guidelines.

Advances in bioconcentration prediction

A reexamination of the log-log relationship between the bioconcentration factor in fish (BCF) and different types of P OW data for a set of 49 compounds of diverse chemical range reveals that the overall correlation between log BCF and log P OW is only moderate but gets significantly improved by restriction to the subset of CHCs and PAHs. Furthermore, a comparison of different theoretical descriptors shows that for the combined CHCs and PAHs the solvent accessible surface area (SASA) and the molar refraction (MR) are better predictors of log BCF than calculated log P OW values according to Leo's CLOGP-3.42 program.