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PubMed1997

Results of a survey of infectious disease testing practices by organ procurement organizations in the United States.

BACKGROUND: Information related to infectious disease testing policies and practices of organ procurement organizations in the United States does not currently exist. METHODS: A total of 63 organ procurement organizations in the United States were surveyed during May 1996. Participants responded to a detailed questionnaire concerning infectious disease tests performed for tissue and solid organ donors and policies related to the reporting and notification of positive test results. RESULTS: The response rate was 77.8%. The majority of testing is performed by hospital laboratories with an expected turnaround time of 5 hr or less by 71% of organ procurement organizations. Almost all routinely perform screening tests for human immunodeficiency virus, hepatitis C virus, cytomegalovirus, syphilis, human T lymphocyte virus I, and hepatitis B surface antigen. Other tests are performed with greater variability. Although the majority of organ procurement organizations perform confirmatory tests when screening tests are positive, 35% do not perform confirmatory testing or do so only sporadically. There are a wide range of policies concerning the subsequent reporting of positive infectious disease tests and to whom results should be reported. CONCLUSIONS: Infectious disease testing policies of organ procurement organizations, particularly for solid organs, demonstrate variability in interpretation and perceived significance of positive test results, the initiation or need for reflex and confirmatory testing, the reporting of positive results, and to whom positive test results should be reported. There is a need for a consistent national policy for appropriate infectious disease testing and reporting of results.

AIDS Serodiagnosis↗
PubMed1999

A European perspective on organ procurement: breaking down the barriers to organ donation.

A worldwide shortage of donor organs has led to the development of national and international systems for organ procurement and allocation. Such systems promote organ donation and ensure fair distribution of available donor organs through a combination of legislation, organ exchange organizations (OEOs), transplant coordinators, publicity campaigns, donor cards, and professional training programs. The development of national and international OEOs is central to this process because they maintain waiting lists and allocate organs in the most appropriate way. Most countries also employ transplant coordinators whose role involves promoting links between transplant centers and intensive care units, establishing protocols for organ donation, and helping hospital staff deal with the sensitive issues involved in organ donation. Educational initiatives, such as the European Donor Hospital Education Programme developed by Eurotransplant is now used in over 30 countries worldwide. The program aims to improve professionals' understanding of the legal and ethical issues involved in transplantation, to help them communicate effectively and sympathetically with bereaved families, and to increase organ donation rates. Other initiatives include programs such as the Donor Action Programme, which was set up by professional organizations in the US and Europe aiming to help hospitals establish tailor-made organ procurement policies to ensure that all potential donors can be identified and reported and the needs of unfortunate families can be met in a caring and sensitive manner.

Ethics, Medical↗
PubMed1990

Organ donor management and organ outcome: a 6-year review from a Level I trauma center.

A retrospective review of 114 solid organ donors over a 6-year period (1982-1987) was undertaken to identify problems in organ donor management and determine outcome of donated organs. Admission GCS was less than or equal to 4 in 84% of the donors. Complications included hypotension (81%), multiple transfusion requirements (63%), diabetes insipidus (53%), DIC (28%), arrhythmias (27%), cardiac arrest requiring CPR (25%), pulmonary edema (19%), hypoxia (11%), acidosis (11%), seizures (10%), and positive bacterial cultures (10%). Only 18% of organs were procured within 3 hours of brain death; 23% were procured more than 6 hours later. Six patients excluded from this study suffered cardiovascular collapse before their organs could be retrieved. From 114 organ donors, consent was obtained to procure 224 kidneys, 77 livers, 62 hearts, 35 pancreata, and ten heart-lung units. All 224 donated kidneys were procured and 202 were ultimately transplanted. Of 77 donated livers, 32 were procured; 31 transplanted. Of 62 donated hearts, 38 were procured; 29 transplanted and nine used for valves. Ten heart-lung units were donated; six were procured and transplanted. Of 35 donated pancreata, 11 were procured; only five were transplanted. Reasons for failure of donated organs to be procured or transplanted included abnormal organ characteristics, lack of compatible recipients, unavailability of surgical teams, organ injury during procurement, intraoperative arrest, and anatomic limitations precluding multiple organ procurement. This study identifies characteristics of organ donors and common organ-threatening complications. Rapid and continuing resuscitation of clinically brain dead trauma victims is mandatory.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2002

Multiple-organ harvesting for models of isolated hemoperfused organs of slaughtered pigs.

Single- and multiorgan transplantations for the treatment of terminal cardiac, pulmonary, hepatic and renal diseases gain therapeutic importance and transplantation research using mammalian models of isolated perfused organs resembles a major field for the improvement of transplantation techniques. We established a new method of multiple organ harvesting from slaughterhouse pigs which may be used to reduce numbers of laboratory animals. 492 organs (hearts n = 191, lungs n = 108, livers n = 48, kidneys n = 145) were harvested, perfused with autologous blood to prevent artificial perfusion effects and examined for optimal organ harvesting and preservation conditions by analysing organ specific perfusion parameters. For each organ, specific techniques in regard to dissection, cannulation and periods of ischemia have to be applied to guarantee appropriate organ perfusion. In summary, our data indicate that porcine organs obtained by multiple organ harvesting from commercial slaughterhouse animals can be efficiently used for isolated and perfused organ models. The harvesting process did not disturb the commercial use of the animals. Thus, multiple or single organ harvesting may be a useful method to reduce the use of laboratory animals.

Animals↗
PubMed1964

THE STRUCTURE AND ORGANIZATION OF, AND THE RELATIONSHIP BETWEEN THE ORGANIC MATRIX AND THE INORGANIC CRYSTALS OF EMBRYONIC BOVINE ENAMEL.

Electron microscope and electron diffraction studies of developing embryonic bovine enamel have revealed the organization of the organic matrix and the inorganic crystals. The most recently deposited inorganic crystals located at the ameloblast-enamel junction are thin plates, approximately 1300 A long, 400 A wide, and 19 A thick. During maturation of the enamel, crystal growth occurs primarily by an increase in crystal thickness. Statistical analyses failed to show a significant change in either the width or the length of the crystals during the period of maturation studied. Even in the earliest stages of calcification, the crystals are organized within the prisms so that their long axes (c-axes) are oriented parallel to the long axes of the prisms but randomly distributed about their long axes. With maturation of the enamel, the crystals become more densely packed and more highly oriented within the prisms. The organic matrix in decalcified sections of enamel is strikingly similar in its over-all organization to that of the fully mineralized tissue. When viewed in longitudinal prism profiles, the intraprismatic organic matrix is composed of relatively thin dense lines, approximately 48 A wide, which are relatively parallel to each other and have their fiber axes parallel to the long axes of the prisms within which they are located. Many of these dense lines, which have the appearance of thin filaments, are organized into doublets, the individual 48 A wide filaments of the doublets being separated by approximately 120 A. When observed in oblique prism profiles, the intraprismatic organic matrix is likewise remarkably similar in general orientation and organization to that of the fully mineralized tissue. Moreover, the spaces between adjacent doublets or between single filaments have the appearance of compartments. These compartments, more clearly visualized in cross- or near cross-sectional prism profiles, are oval or near oval in shape. Therefore, the appearance of the intraprismatic organic matrix (in longitudinal, oblique, and cross-sectional prism profiles) indicates that it is organized into tubular sheaths which are oriented with their long axes parallel to the long axes of the prisms in which they are located, but randomly oriented about their own long axes, an orientation again remarkably "blue printing" that of the inorganic crystals. The predominant feature of the walls of the tubular sheaths, when viewed in cross- or near cross-section, is that of continuous sheets, although in many cases closely packed dot-like structures of approximately 48 A were also observed, suggesting that the wall of the sheaths consists of a series of closely packed filaments. The 48 A wide dense lines (filaments) representing the width of the sheath wall were resolved into two dense strands when viewed in longitudinal prism profiles. Each strand was 12 A wide and was separated by a less electron-dense space 17 A wide. The intraprismatic organic matrix is surrounded by a prism sheath which corresponds in mineralized sections to the electron-lucent uncalcified regions separating adjacent prisms. Structurally, the prism sheaths appear to consist of filaments arranged in basket-weave fashion.

Ameloblasts↗
PubMed2000

Epidermal sensory organs of moles, shrew moles, and desmans: a study of the family talpidae with comments on the function and evolution of Eimer's organ.

The epidermal sensory organs of members of the family Talpidae (moles, shrew-moles, and desmans) were investigated and compared to determine the range of sensory specializations and better understand how they evolved. Small domed mechanosensory organs called 'Eimer's organs' were present on the rhinarium of nearly all species of talpids, but not among the sister group of shrews (Soricidae) or other insectivore families. This suggests that the common ancestor to the talpids possessed Eimer's organs. Two species of moles from the driest habitats did not exhibit Eimer's organs - suggesting that their sensory organs degenerated in response to harsh, abrasive soil conditions. The semi-aquatic desmans uniquely possessed tiny sensory hairs interspersed with their Eimer's organs; these may act to sense water currents. Some species exhibited a subdivided, star-like, rhinarium - resembling an early embryonic stage of the star-nosed mole and providing clues to the evolution of the star. A single genera (Uropsilus) that branched off early in the evolution of the talpids had Eimer's organ-like structures but lacked some typical components. These findings fill a major gap in our knowledge of talpid sensory biology and suggest (1) how Eimer's organs evolved, (2) how the unusual appendages of the star-nosed mole evolved, (3) that the evolution of Eimer's organ is convergent with the mechanosensory push-rod of monotremes. The results also demonstrate the features that distinguish Eimer's organ from similar configurations of sensory receptors in other mammalian skin surfaces. Finally, a mechanism for Eimer's organ function in detecting object and prey specific surface features is proposed.

Animals↗
PubMed1999

Polyspecific organic anion transporting polypeptides mediate hepatic uptake of amphipathic type II organic cations.

Hepatic uptake of albumin-bound amphipathic organic cations has been suggested to be mediated by multispecific bile salt and organic anion transport systems. Therefore, we investigated whether the recently cloned rat organic anion transporting polypeptides 1 and 2 as well as the human organic anion transporting polypeptide might be involved in the hepatocellular uptake of bulky type II organic cations. In cRNA-injected Xenopus laevis oocytes, all three carriers mediated uptake of the known type II model compounds N-(4, 4-azo-n-pentyl)-21-deoxy-ajmalinium and rocuronium, whereas the newly synthesized type II model compounds N-methyl-quinine and N-methyl-quinidine were transported only by the human organic anion transporting polypeptide. This carrier-mediated uptake of N-methyl-quinine and N-methyl-quinidine was sodium-independent and saturable with apparent K(m) values of approximately 5 and approximately 26 microM, respectively. In contrast to bulky type II organic cations, more hydrophilic type I organic cations such as tributylmethylammonium and choline were not transported by any of the organic anion transporting polypeptides. These findings demonstrate that organic anion transporting polypeptides can also mediate hepatocellular uptake of type II organic cations, whereas uptake of small and more water-soluble type I cations is mediated by different transport systems such as the organic cation transporters.

Animals↗
PubMed2003

Retrieving organs from non-heart-beating organ donors: a review of medical and ethical issues.

PURPOSE: The increasing gap between numbers of individuals awaiting organ replacement surgery and the supply of organs available for transplant underpins attempts to increase the number of organs available. One practice, used in other countries, is the recovery of organs from non-heart-beating organ donors (NHBD). The purpose of this review is to discuss ethical issues surrounding the use of organs from these donors. SOURCE: Narrative review from selected Medline references, and other published reports. PRINCIPAL FINDINGS: NHBD protocols have been established in many countries including the United States. Despite numerous publications, and extensive debate in the literature, significant ethical issues remain unresolved in the retrieval of organs from donors that have died from cessation of cardiac activity. The ethical concerns primarily arise in the determination of death, the tension between the time constraints on recovering organs viable for transplantation, and procedures to enhance organ viability. Despite a concerted effort in the United States, less than half of the organ procurement organizations have NHBD protocols. CONCLUSION: Canadian centres can learn from the difficulties encountered in other centres that have developed NHBD protocols. A moratorium on Canadian NHBD protocols should be considered until a National consensus reflecting Canadian values has been undertaken.

Brain Death↗
PubMed1990

Organ tropism of Sendai virus in mice: proteolytic activation of the fusion glycoprotein in mouse organs and budding site at the bronchial epithelium.

Wild-type Sendai virus is exclusively pneumotropic in mice, while a host range mutant, F1-R, is pantropic. The latter was attributed to structural changes in the fusion (F) glycoprotein, which was cleaved by ubiquitous proteases present in many organs (M. Tashiro, E. Pritzer, M. A. Khoshnan, M. Yamakawa, K. Kuroda, H.-D. Klenk, R. Rott, and J. T. Seto, Virology 165:577-583, 1988). These studies were extended by investigating, by use of an organ block culture system of mice, whether differences exist in the susceptibility of the lung and the other organs to the viruses and in proteolytic activation of the F protein of the viruses. Block cultures of mouse organs were shown to synthesize the viral polypeptides and to support productive infections by the viruses. These findings ruled out the possibility that pneumotropism of wild-type virus results because only the respiratory organs are susceptible to the virus. Progeny virus of F1-R was produced in the activated form as shown by infectivity assays and proteolytic cleavage of the F protein in the infected organ cultures. On the other hand, much of wild-type virus produced in cultures of organs other than lung remained nonactivated. The findings indicate that the F protein of wild-type virus was poorly activated by ubiquitous proteases which efficiently activated the F protein of F1-R. Thus, the activating protease for wild-type F protein is present only in the respiratory organs. These results, taken together with a comparison of the predicted amino acid substitutions between the viruses, strongly suggest that the different efficiencies among mouse organs in the proteolytic activation of F protein must be the primary determinant for organ tropism of Sendai virus. Additionally, immunoelectron microscopic examination of the mouse bronchus indicated that the budding site of wild-type virus was restricted to the apical domain of the epithelium, whereas budding by F1-R occurred at the apical and basal domains. Bipolar budding was also observed in MDCK monolayers infected with F1-R. The differential budding site at the primary target of infection may be an additional determinant for organ tropism of Sendai virus in mice.

Animals↗
PubMed2003

Decreased activity of basolateral organic ion transports in hyperuricemic rat kidney: roles of organic ion transporters, rOAT1, rOAT3 and rOCT2.

We investigated organic anion and cation transport activity and the expression of several organic ion transporters in hyperuricemic rat kidney. Feeding oxonic acid, an inhibitor of uric acid metabolism, and uric acid for 10 days significantly increased plasma uric acid level. Plasma creatinine and blood urea nitrogen concentrations also increased in hyperuricemic rats, indicating impaired renal function. The accumulation of organic anions, p-aminohippurate (PAH) and methotrexate, and cations, tetraethylammonium (TEA) and cimetidine, into renal slices was markedly decreased, suggesting decreased transport activity for organic anions and cations at the basolateral membrane in the kidney. The expression levels of basolateral organic anion transporters rOAT1 and rOAT3, and organic cation transporter, rOCT2, significantly decreased in hyperuricemic rat kidney as assessed by mRNA and protein levels. In contrast, the expression of rOCT1 was unaltered by hyperuricemia at both mRNA and protein levels. Moreover, the mRNA expression of kidney-specific organic anion transporters, OAT-K1 and OAT-K2, and organic anion transporting polypeptide (oatp) 1, which localize at the brush-border membrane in the kidney, was unchanged in hyperuricemic rats. In conclusion, we showed decreased basolateral organic anion and cation transport activity, accompanied by a specific decrease in rOAT1, rOAT3 and rOCT2 expression in hyperuricemic rat kidney. These phenomena partly contribute to the changed renal disposition of organic anions and cations in hyperuricemia.

Animals↗
PubMed1995

Hepatitis C infection in cadaver organ donors: strategies to reduce transmission of infection and prevent organ waste.

The transmission of hepatitis C virus (HCV) by organ transplantation has been unequivocally demonstrated. Among recipients of organs from anti-HCV-positive donors, 57%-96% test positive for HCV RNA. Consequently, several organ procurement organizations have adopted a policy restricting the use of anti-HCV-positive donors to life-saving transplants (heart, liver, or lung). The differences in the rate of transmission of HCV infection by anti-HCV-positive donors could be related to the prevalence of HCV RNA among these donors. In a national collaborative study of 3,078 cadaver organ donors from eight organ procurement organizations in the United States, the prevalence of anti-HCV antibodies and HCV RNA were 4.2% and 2.4%, respectively. The sensitivity and negative predictive value of anti-HCV antibodies for HCV RNA were 100%. However, despite a specificity of 98.1%, the positive predictive value was only 55.1%. Discarding organs from enzyme-linked immunosorbent assay 2-positive donors would eliminate transmission, but organs from 1.88% of donors would be wasted. Clinical and laboratory characteristics did not distinguish anti-HCV-positive donors with and without HCV RNA. Hence, to reduce waste it is necessary to develop confirmatory tests with a higher specificity for HCV RNA than those that are currently available. Even if anti-HCV-positive but HCV RNA-negative donors could be identified and utilized, 2.4% of cadaver organ donors that test positive for serum HCV RNA would remain unsuitable for transplantation of non-life-saving organs. Hence, several authors have suggested the use of kidneys from anti-HCV-positive donors in recipients with pre-existing HCV infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Cadaver↗
PubMed1997

Rostral floor plate (flexural organ) secretes glycoproteins immunologically similar to subcommissural organ glycoproteins in dogfish (Scyliorhinus canicula) embryos.

The subcommissural organ of vertebrates secretes glycoproteins into the cerebrospinal fluid of the third cerebral ventricle. This material polymerizes in Reissner's fiber. During ontogenetic development, besides the subcommissural organ, the ependyma lining the pontine flexure constitutes an additional Reissner's fiber-secreting gland named flexural organ. We have studied the secretion of the flexural organ and the subcommissural organ in dogfish (Scyliorhinus canicula) embryos using three different antisera and the lectins concanavalin A and wheat germ agglutinin. AFRU is an antiserum against the bovine Reissner's fiber, Ab-600 is an antiserum against 600 kDa dogfish subcommissural organ glycoproteins; and APSO is an antiserum against immunoaffinity purified bovine subcommissural organ secretory glycoproteins. These three antisera immunostained the flexural organ indicating that it contains epitopes similar to those present in bovine and dogfish subcommissural organ glycoproteins. It seems highly probable that the flexural organ and the subcommissural organ of dogfish embryos secrete similar compound(s). Other ependymal regions were also immunostained with Ab-600 and APSO antisera. Then, Reissner's fiber-like glycoproteins were transiently expressed by most embryonary ependymal cells. These glycoproteins might play a role in the development of the central nervous system of vertebrates.

Animals↗
PubMed2001

Cultural analysis of an organ procurement organization.

Organ procurement organizations are a critical link in the acquisition, placement, and transport of human organs for transplantation. Employed within the organ procurement organizations are organ transplant coordinators and support staff who constitute the front line in the challenge to diminish the gap between the supply and demand for organs. Responsibilities are emotionally and physiologically demanding as employees regularly face death and grieving families with empathy and commitment. This study describes and interprets dominant themes embedded in the culture of one such organ procurement organization, geographically located in northeastern United States. The authors used ethnographic research methods to understand the shared meaning system of the members of this organization. Identified themes included coping and sharing, conflicting priorities and uncertainty, and mission and reward. The influence of each theme on the organization is discussed with prescriptive implications for managerial practice.

Burnout, Professional↗
PubMed1992

Ethical considerations in living organ donation and a new approach. An Advance-Directive Organ Registry.

Living organ donation should be recognized as an ethical compromise to the principle of nonmaleficence (doing no harm), given the risks healthy donors are allowed to assume. Living organ donation should be reserved for situations in which there is no acceptable alternative. Increasing the availability of cadaveric organs is most desirable, since it would decrease (although probably not eliminate) the need for living organ transplantation and would provide organs (ie, hearts) that could not otherwise be obtained. We propose the development of an incentive-based Advance-Directive Organ Registry, in which all adults are encouraged to register their advance directive regarding organ donations. Those individuals agreeing to permit usable organs to be taken at the time of death would receive priority for organs generated by the program, should a transplant become necessary when there is a shortage of organs. The proposed Advance-Directive Organ Registry is firmly founded on the principles of autonomy, beneficence, and justice.

Advance Directives↗
PubMed1999

Characterization of the surface organization of nanostructured hybrid organic-inorganic materials by time-of-flight secondary ion mass spectrometry

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) has been used to analyse the surface composition of organic-inorganic hybrid solids obtained by a sol-gel process. Gels of type O(1.5)Si-R-SiO(1. 5), obtained from bis-silylated precursors (R'O)(3)-R-Si(OR')(3) (R' = Me, Et and R = (-CH(2))(n)-, n = 1, 2, 6, 10, 12;--CH=CH-; (-CH(2))(3)NH(CH(2))(3)-; 1, 1'-ferrocenyl; (CH(2))(n)-Ph-(CH(2))(n)- with Ph = 1,4-phenylene and n = 0, 1, 2; Ph = 1,3,5-phenyl and n = 0) were analysed. The results were highly dependent on the nature of the organic group. When the organic group was small or 'rigid', the main peaks detected corresponded to SiOH and SiOR' residual groups. Fragment ions from the organic group were poorly detected in this case. When the organic group was larger and more 'flexible', characteristic mass fragment ions were detected at higher relative intensities, indicative of a different organization of the organic units in the solid. TOF-SIMS clearly showed the differences between the xerogels derived from mono- and bis-silylated organic precursors : the organic group is present at the surface of mono-silylated xerogels, whereas for bis-silylated ones, the organization is dependent on the length and the flexibility of the organic units. These TOF-SIMS results are in agreement with other features already reported. Copyright 1999 John Wiley & Sons, Ltd.

Journal Article↗
PubMed2006

Ultrastructural organization of the anal organs in the anal capsule of Craterostigmus tasmanianus Pocock, 1902 (Chilopoda, Craterostigmomorpha).

We describe the ultrastructural organization of the anal organs of Craterostigmus tasmanianus, which are located on the ventral side of the bivalvular anal capsule. Each part of the capsule bears four pore fields with several anal pores. The pores lead into a pore canal, which is surrounded by the single-layered epithelium of the anal organs. Each anal organ is composed of four different cell types: transporting cells of the main epithelium, junctional cells, isolated epidermal glands, and the cells forming the pore canal. The transporting cells exhibit infoldings of the outer cell membranes, forming a basal labyrinth and a poorly developed apical complex. The cells are covered by a specialized cuticle with a widened subcuticular layer. Only the cuticle of the main epithelium is covered by a mucous layer, secreted by the epidermal glands. The ultrastructural organization of the anal organ is comparable to the coxal and anal organs of other pleurostigmophoran Chilopoda. It is likely that the coxal and anal organs of the Pleurostigmophora are homologous, due to their identical ultrastructural organization. Differences concerning the location on the trunk of Pleurostigmophora are not sufficient to reject a hypothesis of homology. Anal organs are found not only in Craterostigmomorpha, but also in most adult Geophilomorpha, and in larvae and most adults of Lithobiomorpha. The anal organs of C. tasmanianus are thought to play an important role in the uptake of atmospheric water. J. Morphol.

Anal Canal↗
PubMed2003

Nonionic organic solute sorption onto two organobentonites as a function of organic-carbon content.

Sorption of three nonionic organic solutes (benzene, trichloroethene, and 1,2-dichlorobenzene) to hexadecyltrimethylammonium bentonite (HDTMA bentonite) and benzyltriethylammonium bentonite (BTEA bentonite) was measured as a function of total organic-carbon content at quaternary ammonium cation loadings ranging from 30 to 100% of the clay's cation-exchange capacity. Sorption of all three solutes to HDTMA bentonite was linear and sorption of all three solutes by the HDTMA bentonite increased as the organic-carbon content of the clay increased. 1,2-Dichlorobenzene sorbed most strongly to HDTMA bentonite, followed by benzene and TCE. The stronger sorption of benzene to HDTMA bentonite compared to TCE was unexpected based on a partition mechanism of sorption and consideration of solute solubility. LogK(oc) values for all three solutes increased with organic-carbon content. This suggests that the increased organic-carbon content alone may not explain the observed increase in sorption capacity. Sorption of the three solutes to BTEA bentonite was nonlinear and solute sorption increased with decreasing organic-carbon content, with a peak in the magnitude of solute sorption occurring at an organic-carbon content corresponding to 50% of CEC. Below 50% of CEC, sorption of all three solutes to BTEA bentonite decreased with decreasing organic-carbon content. Surface area measurements indicate that the surface area of both organobentonites generally decreased with increasing organic-carbon content. Since nonionic organic solute sorption to BTEA bentonite occurs by adsorption, the reduced sorption is likely caused by the reduction in surface area corresponding to increased organic-cation loading.

Journal Article↗
PubMed2003

Sense or no-sense of the sum parameter for water soluble "adsorbable organic halogens" (AOX) and "absorbed organic halogens" (AOX-S18) for the assessment of organohalogens in sludges and sediments.

"AOX" is the abbreviation of the sum parameter for water soluble "adsorbable organic halogens" in which 'A' stands for adsorbable, 'O' for organic and 'X' for the halogens chlorine, bromine and iodine. After the introduction of the AOX in 1976, this parameter has been correctly used for "real" AOX constituents (DDT and its metabolites, PCBs, etc.) but also misused for non-adsorbable adsorbed OX-compounds, mostly high molecular organohalogens in plants and even to inorganic compounds being neither organic nor adsorbable. The question of natural "Adsorbable Organic Halogens" (AOX) formed by living organisms and/or during natural abiogenic processes has been definitively solved by the known existence of already more than 3650 organohalogen compounds, amongst them the highly reactive, cancerogenic vinyl chloride (VC). The extension of the AOX to AOX-S18 for Sludges and Sediments, in which A stands for adsorbed (not for adsorbable) is questionable. It includes the most important water insoluble technical organochlorine product: polyvinyl chloride, PVC. In addition to organic halogens it also includes inorganic, mineralogenic halides, incorporated mainly in the crystal lattice of fine grained phyllosilicates, the typical clay minerals (kaolinite, montmorillonite, illite and chlorite) which are main constituents of sediments and sedimentary rocks representing the major part of the sedimentary cover of the earth. Other phyllosilicates, biotite and muscovite, major constituents of granites and many metamorphic rocks (gneiss and mica schist) will also contribute to the AOX-S18 especially in soils as result of weathering processes. Since chlorine is incorporated into the mineral structure and, as a consequence, not soluble by the nitric acid analytical step (pH 0.5) of the S18 determination, it will account to the AOX-S18 in the final charcoal combustion step at temperatures >950 degrees C. After heavy rainfalls sewage sludge composition is strongly influenced by mineralogenic components derived from the erosion of fine grained sediments or soils. Assuming 50% geogenic particles with a mean Cl concentration of 103 mg/kg (as in shales and clays) the mineralogenic Cl-content could add about 50 mg/kg to the organic AOX in sewage sludge. The occurrence of insoluble and non-adsorbable PVC in sewage sludge exhibits the same problems as the mineralogenic constituents: a detection as AOX-S18 is possible when the final high temperature analytical step is applied. Plants as major sources of organohalogens have never been doubted. Only recently [Science 295 (2002) 985] based on the determination of the form of Cl with near-edge X-ray adsorption fine structure (NEXAFS) spectroscopy and extended X-ray adsorption showed the variations in the inorganic Cl(-) and organo-Cl compounds with increasing humification of plant leaves from "fresh leaves--senescent leaves on plants--senescent leaves on soil--powdered top soil--isolated soil humus". His finding of exclusively inorganic Cl(-) in the starting material (fresh leaves) is controverse to our earlier results indicating the presence of ionic inorganic Cl together with water insoluble absorbed organohalogens (AOX-S18) in eight different macrophytes of both terrestrial and marine environments. Our research on AOX in interstitial water of anaerobic limnic sediments has led to the role of bromine playing in the diagenesis of the organic matter of sediments. In sediments of Lake Constance Br(-) concentrations in lake water at the sediment water interface increased from <0.01 to 0.25 mg/l in the pore water at 77 cm sediment depth. In the Neckar River a Br concentrations of 0.02 mg/l at the water/sediment interface increasing to 0.74 mg/l in pore water in 85 cm depth was found. Here a parallel development could be found with ammonium concentration and alkalinity. The very high positive correlation ammonium:bromide and bromide:alkalinity leads to the conclusion, that bromine, originally a high molecular constituent of the organic matter, is released as bromide during an early dehalogenation stage of diagenesis. The mlusion, that bromine, originally a high molecular constituent of the organic matter, is released as bromide during an early dehalogenation stage of diagenesis. The main general reason to discard the AOX sum parameter as a whole lies in the fact, that adsorbable halogenated substances cannot a priori be categorized as natural/anthropogenic, biotic/abiotic, harmful/harmless. If applied to sludges and sediments, adsorbed organohalogens are not water soluble and therefore not adsorbable, and mineralogenic halogens (X) are neither organic nor adsorbable, and therefore by definition no AOX.

Absorption↗