Health Risk Assessment for Cyanobacterial Toxins in Seafood

Cyanobacteria (blue-green algae) are abundant in fresh, brackish and marine waters worldwide. When toxins produced by cyanobacteria are present in the aquatic environment, seafood harvested from these waters may present a health hazard to consumers. Toxicity hazards from seafood have been internationally recognised when the source is from marine algae (dinoflagellates and diatoms), but to date few risk assessments for cyanobacterial toxins in seafood have been presented. This paper estimates risk from seafood contaminated by cyanobacterial toxins, and provides guidelines for safe human consumption

Evaluating Evidence for Association of Human Bladder Cancer with Drinking-Water Chlorination Disinfection By-Products

Exposure to chlorination disinfection by-products (CxDBPs) is prevalent in populations using chlorination-based methods to disinfect public water supplies. Multifaceted research has been directed for decades to identify, characterize, and understand the toxicology of these compounds, control and minimize their formation, and conduct epidemiologic studies related to exposure. Urinary bladder cancer has been the health risk most consistently associated with CxDBPs in epidemiologic studies. An international workshop was held to (1) discuss the qualitative strengths and limitations that inform the association between bladder cancer and CxDBPs in the context of possible causation, (2) identify knowledge gaps for this topic in relation to chlorine/chloramine-based disinfection practice(s) in the United States, and (3) assess the evidence for informing risk management. Epidemiological evidence linking exposures to CxDBPs in drinking water to human bladder cancer risk provides insight into causality. However, because of imprecise, inaccurate, or incomplete estimation of CxDBPs levels in epidemiologic studies, translation from hazard identification directly to risk management and regulatory policy for CxDBPs can be challenging. Quantitative risk estimates derived from toxicological risk assessment for CxDBPs currently cannot be reconciled with those from epidemiologic studies, notwithstanding the complexities involved, making regulatory interpretation difficult. Evidence presented here has both strengths and limitations that require additional studies to resolve and improve the understanding of exposure response relationships. Replication of epidemiologic findings in independent populations with further elaboration of exposure assessment is needed to strengthen the knowledge base needed to better inform effective regulatory approaches

Co-ordinated Airborne Studies in the Tropics (CAST)

This is the author accepted manuscript. The final version is available from the American Meteorological Society via http://dx.doi.org/10.1175/BAMS-D-14-00290.1The Co-ordinated Airborne Studies in the Tropics (CAST) project is studying the chemical composition of the atmosphere in the Tropical Warm Pool region to improve understanding of trace gas transport in convection. The main field activities of the CAST (Co-ordinated Airborne Studies in the Tropics) campaign took place in the West Pacific in January/February 2014. The field campaign was based in Guam (13.5°N, 144.8°E) using the UK FAAM BAe-146 atmospheric research aircraft and was coordinated with the ATTREX project with the unmanned Global Hawk and the CONTRAST campaign with the Gulfstream V aircraft. Together, the three aircraft were able to make detailed measurements of atmospheric structure and composition from the ocean surface to 20 km. These measurements are providing new information about the processes influencing halogen and ozone levels in the tropical West Pacific as well as the importance of trace gas transport in convection for the upper troposphere and stratosphere. The FAAM aircraft made a total of 25 flights between 1°S-14°N and 130°-155°E. It was used to sample at altitudes below 8 km with much of the time spent in the marine boundary layer. It measured a range of chemical species, and sampled extensively within the region of main inflow into the strong West Pacific convection. The CAST team also made ground-based measurements of a number of species (including daily ozonesondes) at the Atmospheric Radiation Measurement program site on Manus Island, Papua New Guinea (2.1°S, 147.4°E). This article presents an overview of the CAST project focussing on the design and operation of the West Pacific experiment. It additionally discusses some new developments in CAST, including flights of new instruments on the Global Hawk in February/March 2015.CAST is funded by NERC and STFC, with grant NE/ I030054/1 (lead award), NE/J006262/1, NE/J006238/1, NE/J006181/1, NE/J006211/1, NE/J006061/1, NE/J006157/1, NE/J006203/1, NE/J00619X/1, and NE/J006173/1. N. R. P. Harris was supported by a NERC Advanced Research Fellowship (NE/G014655/1). P. I. Palmer acknowledges his Royal Society Wolfson Research Merit Award. The BAe-146-301 Atmospheric Research Aircraft is flown by Directflight Ltd and managed by the Facility for Airborne Atmospheric Measurements, which is a joint entity of the Natural Environment Research Council and the Met Office. The authors thank the staff at FAAM, Directflight and Avalon Aero who worked so hard toward the success of the aircraft deployment in Guam, especially for their untiring efforts when spending an unforeseen 9 days in Chuuk. We thank the local staff at Chuuk and Palau, as well as the authorities in the Federated States of Micronesia for their help in facilitating our research flights. Special thanks go to the personnel associated with the ARM facility at Manus, Papua New Guinea without whose help the ground-based measurements would not have been possible. Thanks to the British Atmospheric Data Centre (BADC) for hosting our data and the NCAS Atmospheric Measurement Facility for providing the radiosonde and ground-based ozone equipment. Chlorophyll-a data used in Figure 1 were extracted using the Giovanni online data system, maintained by the NASA GES DISC. We also acknowledge the MODIS mission scientists and associated NASA personnel for the production of this data set. Finally we thank many individual associated with the ATTREX and CONTRAST campaigns for their help in the logistical planning, and we would like to single out Jim Bresch for his excellent and freely provided meteorological advice

Tumour promotion by the cyanobacterial toxin microcystin / by Andrew Raymond Humpage.

Bibliography: leaves 235-265.xvi, 265 leaves : ill. ; 30 cm.Examines the tumour promoting effects of the microcystins through a long-term study in which cyanobacterial extract containing a range of microcystins was given in drinking water to mice previously treated with the tumour initiator N-nitroso-N-methyluren by gavage ; and through examining the effects of pure microcystin-LR in cultured primary hepatocytes from immature mice.Thesis (Ph.D.)--University of Adelaide, Dept. of Clinical and Experimental Pharmacology, 1998

Cyanobacterial Harmful Algal Blooms: Chapter 15: Cyanotoxins Workgroup Report

The Cyanotoxins Workgroup was charged with the identification and prioritization of research needs associated with: the identification of cyanotoxins; toxicokinetics and toxicodynamics of cyanotoxins; human susceptibility to the toxins; cyanobacterial genetics/omics and factors for inclusion in predictive models of toxin production; and risk reduction from an intentional or accidental release of cyanotoxins. Papers presented for the Cyanotoxins Session of the symposium on toxin types, toxicokinetics, and toxicodyamics (See Humpage this volume), cyanobacterial genetics of toxin production (See Neilan this volume), and parameters related to human risks from cyanobacterial exposure (See Love this volume) set the stage for Cyanotoxins Workgroup discussions. A consensus was achieved regarding the need to focus on the major identified classes of cyanotoxins. The group expressed the belief that the most significant toxic components of presently occurring harmful algal blooms have been identified, and the knowledge gaps for these most prevalent toxins are great enough to warrant the attention of most of our future research. This belief does not negate the need to study mixtures of cyanotoxins and toxin precursors, especially those most likely to occur within a given bloom. Moreover, there is also a significant likelihood that novel cyanobacterial blooms and toxins will continue to emerge, and future identification of unknown bloom-forming species and their toxins will require ongoing diligence

Novel toxicity associated with a Limnothrix-like species : mouse bioassay results

Background & Aims: A search for novel cylindrospermopsin (CYN) producers found a Limnothrix strain that inhibited protein synthesis but did not contain detectable CYN or analogues (HPLC, LC-MS, ELISA), nor the CYN gene (Bernard et al 2010). Methods: Mouse bioassays (time-course up to seven days, and set times up to 24h) were performed followed by detailed post-mortem (PM) dissections and histopathology. By 3h, these reduced but clear mucoid diarrhoea (containing sloughed endothelium and blood cells) was observed. Body weights were reduced by 24h and remained below controls for 7d. Liver and spleen weights (% body weight) increased by 4h and remained high until at least 24h. Histopathology (10-24h) indicated cell death in the small intestine (widespread), liver and kidneys. White blood cell numbers increased in the circulation, spleen and lungs. Conclusions: Limnothrix produces a potent in vivo cytotoxin. It is water-extractable and produced by a commonly occurring genus. Hence it is a potential risk to drinking water sources. We are currently (1) clarifying the genetic identity of the toxic strain, (2) determining its Australian distribution, (3) purifying and characterising the active compound, and (4) investigating its mechanism of action post-mortem (PM) dissections and histopathology. Results: By 0.5h post-injection, signs included extreme sensitivity to touch and sudden noises, and hind limb weakness

Humpage, “Bacterial degradation of microcystin toxins in drinking water eliminates their toxicity

Abstract Microcystin-LR and -LA were readily biodegraded by a bacterium, Sphingpoyxis sp. LH21, in a treated reservoir water. Detection of the microcystins was conducted using high-performance liquid chromatography (HPLC), protein phosphatase 2A (PP2A) inhibition assay and a cell-based cytotoxicity assay. The HPLC results correlated well with the two assays. The decrease in cytotoxicity, coupled with the associated decrease in microcystin concentrations, indicated that no cytotoxic by-products were being generated, highlighting the applicability of biodegradation as a feasible treatment option for effective microcystin removal.

Novel toxic activity associated with the cyanobacteria Limnothrix : use of screening assays for detection

Development of biochemical screening assays for cyanobacterial toxins allows identification of toxins based on known activity. While this may be diagnostic for the toxin or toxin class that the assay has been designed for (e.g. microcystins, cylindrospermopsins) there is also potential to pick up new, unidentified toxins. In this example, screening cyanobacterial samples for the toxin cylindrospermopsin led to the identification of novel toxic activity from the cyanobacterium Limnothrix.The cell-free protein synthesis assay was inhibited by the Limnothrix extract as would be expected when cylindrospermopsin is present. However analysis by immunoassay (ELISA) and analytical techniques (HPLC, LC-MS) could not detect cylindrospermopsin itself. PCR amplification of genes associated with cylindrospermopsin production was also absent. Further characterisation revealed that the toxic responses induced by the Limnothrix extract could not be attributed to other known cyanobacterial toxins. Distinctive toxic effects of the Limnothrix extract in mammalian cells include significant ATP depletion and markedgranulation of cells as observed by both microscopy and flow cytometry. Current work aimsto identify and characterise the toxic agent present. This case highlights how biochemical screening assays can complement analytical techniques for the identification of toxic activity in cyanobacterial samples. Adequate validation of such techniques is required

Taxonomy and ecology of toxin producing Limnothrix

A new toxin produced by a Limnothrix was discovered while screening cyanobacterial samples for the presence of known and unknown toxins as part of an Australian Coal Association Research Project. It is the first time that a toxin-producing freshwater Limnothrix has been described. The features of this cyanobacterium in both field and pure cultures were consistent with the cyanobacterial species Geitlerinema unigranulatum as well as with the earlier Australian descriptions of Limnothrix cf. planctonica. However, genetic analyses closely group this cyanobacterium with the commonly occurring temperate species Limnothrix redekei. Limnothrix may occur as solitary planktonic trichomes, mats on the bottom or within the water column, or in balls floating on the surface. A fine mucilage, often confused with a sheath, may cover older trichomes. The long, thin trichomes may glide into coils, may flex and are not attenuated at the ends. The cylindrical cells are 1.6-2.0 μm wide and 5.0-6.5 μm long. Constriction at the cross walls is generally not observed and cross walls are often indistinct. Refractile granules are present in the cells - near the cell walls and sometimes distributed within the cells. Limnothrix often co-dominates with Cylindrospermopsis raciborskii in both temperate and tropical environments. In the Fitzroy River system, it is often found just above the level of the thermocline. However, toxin producing material has also been isolated from water sampled from major pipelines within the Central Queensland region