The Experts below are selected from a list of 12 Experts worldwide ranked by ideXlab platform

Leusden Fm Van - One of the best experts on this subject based on the ideXlab platform.

  • hazard identification and characterisation and Doseresponse Assessment of spore forming pathogens in cooked chilled food containing vegetables
    2001
    Co-Authors: Leusden Fm Van
    Abstract:

    Een gevarenidentificatie en gevarenkarakterisering, inclusief een summiere dosis respons schatting, voor sporenvormende pathogene bacteri6n (SPB) in gekookte voeding, welke als hoofdbestanddeel groente bevat en gekoeld moet worden bewaard, is uitgevoerd conform de structuur en principes behorend bij een kwantitatieve microbiologische risicoschating zoals beschreven door de Codex Alimentarius Commissie.Indien aanvullende beperkingen en omstandigheden, zoals het vermogen om te kunnen groeien gedurende opslag bij een normale koelkasttemperatuur (4 graden C) of bij een iets te hoge koelkasttemperatuur (10 graden C), aantallen explosies per jaar, aantal ziektegevallen per jaar, mate van fataal zijn van de ziekte, en een relatie met explosies door voedsel dat groente bevat, mee worden genomen dan zijn C. botulinum van groep II en B. cereus gevaren met een hoog risico in bovengenoemde producten. C. botulinum van groep I vormt dan een gemiddeld risico bij bewaring bij een te hoge koelkasttemperatuur. B. subtilis en verwante species en C. perfringens geven een laag risico in dit type producten. Er is een duidelijke relatie tussen blootstelling aan deze organismen en gezondheidseffecten. Een kwantitatieve relatie tussen blootstelling aan een bepaalde concentratie van de SPB of haar toxine en bepaalde effecten die de gezondheid schaden kon niet worden vastgesteld. Dit is voornamelijk toe te schrijven aan incomplete en niet gestandaardiseerde beschrijving van de klinische verschijnselen en het onvermogen om de dosis van organismen en/of toxinen waaraan de patient is blootgesteld te kunnen vaststellen. Op grond van gegevens bij het therapeutisch gebruik van C. botulinum toxine als spierverslapper bij de mens, is een poging gedaan een "veilige" dosis te bereken, die in voedsel zou mogen voorkomen. Deze "veilige" dosis van C. botulinum toxine bedraagt 0,004-0,008 ng/kg lichaamsgewicht. Bij een concentratie van ca 0,06 ng C. botulinum toxine /kg lichaamsgewicht kunnen reeds gezondheidseffecten optreden.

Omoniyi I.t. - One of the best experts on this subject based on the ideXlab platform.

  • Response of Four Phytoplankton Species Found in Some Sectors of Nigerian Coastal Waters to Crude Oil in Controlled Ecosystem
    University of Tehran, 2010
    Co-Authors: Adekunle I.m., Ajijo M.r., Adeofun C.o., Omoniyi I.t.
    Abstract:

    Identification and enumeration of phytoplankton species from Ilaje and Lagos sectors of the Nigerian coastal waters were conducted using standard procedures. Effects of different crude oil concentrations (6 to 50 ppm) on population of Coscnodiscus centralis , Thalassionema frauenfeldii , Odontella mobiliensis , and Ceratium trichoceros at different exposure periods (6 to 42h) via microcosm experiments were then assessed. Results showed that the phytoplankton species consisted of diatoms (83.33%) and dinoflagellates (16.67%) whose abundance ranged from 2 to 516 Cell/mL. Crude oil toxicity varied from 0.06 to 36.43% for C. centralis, 1.41 to 35.58% for C.trichoceros, 1.71 to 46.11% for T. frauenfeldii and 0.66 to 44.90% for O. mobiliensis and showed direct relationship (r -+ 0.81 to +0.97; p < 0.001) with concentration but inverse with exposure period (r = -0.83 to – 0.90; p < 0.001). Vulnerability within 24-h contact decreased in the order: T. frauenfeldii > O. mobiliensis > C. centralis > C. trichoceros. Study is a contribution to the scarce data bank on crude oil Doseresponse Assessment on plankton species in Nigeria, demonstrating that influx of crude oil into the Nigerian coastal waters is a risk factor to ecological status

Steyn Maronel - One of the best experts on this subject based on the ideXlab platform.

  • An Assessment of the human health risks posed by pathogens through various water types
    Bloemfontein: Central University of Technology Free State, 2003
    Co-Authors: Steyn Maronel
    Abstract:

    ThesisThe aim of this study was to determine whether people exposed to the waters at various pOints of use in selected areas of the Mangaung Municipality, were indeed subjected to a probability of infection by the bacterial pathogen Salmonella as previous microbiological monitoring programmes in the area (based on the indicator organism E. coil) had suggested. Applying a Water-related Quantitative Microbial Risk Assessment (WRQMRA) process determined this where domestic and recreational water-use activities lead to the potential ingestion of polluted water. The WRQMRA consisted of the Observed-adverse-effect-Ievel (OAEL) and the Quantitative Microbial Risk Assessment (QMRA) approaches. The OAEL approach (OAELA) was based on the occurrence of E. coli to determine the possible risk of infection, while the QMRA predicted the probable risk of infection by Salmonellae numbers. 80th these approaches were applied to untreated surface waters, used mainly for recreational purposes, as well as to container-stored water (untreated spring water and treated municipal supply water) used for domestic purposes. The OAELA measured the E. coli numbers against various water quality guideline limits for the various water uses, while QMRA calculated the probable infection risk (PI) by applying the four risk Assessment steps of hazard Assessment, exposure Assessment, Doseresponse Assessment and risk characterisation. The results of the OAELA and QMRA were compared to determine whether the use of the OAELA alone (applied by Environmental Health Practitioners) could, on a continual basis, reliably predict the risk of infection. \ Ingestion was the only exposure route investigated, based on selected volumes for the various water-uses. For recreational use of the untreated surface waters in the Renoster Spruit Quartemary Catchment (RSQC), 100mt, 50mt and 10mt were used depending o,n the level of contact with the water. Modified ingestion volumes were extrapolated for various consumer age groups ranging from infants (1,318 mt) to the elderly (865 mt). For the waters in the RSQC, the mean E. coli and Salmonellae occurrences at three sampling sites (RS1, RS2 and BS) were combined and used to calculate the risk. A single-exposure, as well as seasonal (242-day) exposure to the mean, as well as 95'h percentile risk was calculated. For untreated surface waters in the RSQC, both the OAEL and the QMRA approaches indicated a risk of infection to recreational users even for a single exposure event. However, the OAELA either over- or underestimated the risk of infection for singular exposure events and therefore could not predict a continual risk of infection. It is recommended that the full WRQMRA process be used in future. A single-exposure, as well as annual (365-days) risk of infection was calculated for the container-stored (untreated spring and treated municipal supply) water applied for domestic purposes based on the mean and reasonable maximum (95'h percentile) expected dose. Both the OAELA and the QMRA indicated a risk of infection after even a single exposure. However, the OAELA inconsistently over- or underestimated the risk on single sampling events, therefore not reliably indicating the risk of infection on its own. The full WRQMRA process is again recommended, considering several uncertainties that developed throughout the study. It was uncertain to what extent E. coli could indicate the risk of infection by Salmonellae, since it is an indicator of the potential presence of many other pathogens as well. Suitable risk limits lacked for the study area. It is recommended that the entire WRQMRA process developed for this study be applied more often in assessing risk posed by ingestion of water, but with provision for a wider range of pathogens and associated indicator micro-organism

Adekunle I.m. - One of the best experts on this subject based on the ideXlab platform.

  • Response of Four Phytoplankton Species Found in Some Sectors of Nigerian Coastal Waters to Crude Oil in Controlled Ecosystem
    University of Tehran, 2010
    Co-Authors: Adekunle I.m., Ajijo M.r., Adeofun C.o., Omoniyi I.t.
    Abstract:

    Identification and enumeration of phytoplankton species from Ilaje and Lagos sectors of the Nigerian coastal waters were conducted using standard procedures. Effects of different crude oil concentrations (6 to 50 ppm) on population of Coscnodiscus centralis , Thalassionema frauenfeldii , Odontella mobiliensis , and Ceratium trichoceros at different exposure periods (6 to 42h) via microcosm experiments were then assessed. Results showed that the phytoplankton species consisted of diatoms (83.33%) and dinoflagellates (16.67%) whose abundance ranged from 2 to 516 Cell/mL. Crude oil toxicity varied from 0.06 to 36.43% for C. centralis, 1.41 to 35.58% for C.trichoceros, 1.71 to 46.11% for T. frauenfeldii and 0.66 to 44.90% for O. mobiliensis and showed direct relationship (r -+ 0.81 to +0.97; p < 0.001) with concentration but inverse with exposure period (r = -0.83 to – 0.90; p < 0.001). Vulnerability within 24-h contact decreased in the order: T. frauenfeldii > O. mobiliensis > C. centralis > C. trichoceros. Study is a contribution to the scarce data bank on crude oil Doseresponse Assessment on plankton species in Nigeria, demonstrating that influx of crude oil into the Nigerian coastal waters is a risk factor to ecological status

Ajijo M.r. - One of the best experts on this subject based on the ideXlab platform.

  • Response of Four Phytoplankton Species Found in Some Sectors of Nigerian Coastal Waters to Crude Oil in Controlled Ecosystem
    University of Tehran, 2010
    Co-Authors: Adekunle I.m., Ajijo M.r., Adeofun C.o., Omoniyi I.t.
    Abstract:

    Identification and enumeration of phytoplankton species from Ilaje and Lagos sectors of the Nigerian coastal waters were conducted using standard procedures. Effects of different crude oil concentrations (6 to 50 ppm) on population of Coscnodiscus centralis , Thalassionema frauenfeldii , Odontella mobiliensis , and Ceratium trichoceros at different exposure periods (6 to 42h) via microcosm experiments were then assessed. Results showed that the phytoplankton species consisted of diatoms (83.33%) and dinoflagellates (16.67%) whose abundance ranged from 2 to 516 Cell/mL. Crude oil toxicity varied from 0.06 to 36.43% for C. centralis, 1.41 to 35.58% for C.trichoceros, 1.71 to 46.11% for T. frauenfeldii and 0.66 to 44.90% for O. mobiliensis and showed direct relationship (r -+ 0.81 to +0.97; p < 0.001) with concentration but inverse with exposure period (r = -0.83 to – 0.90; p < 0.001). Vulnerability within 24-h contact decreased in the order: T. frauenfeldii > O. mobiliensis > C. centralis > C. trichoceros. Study is a contribution to the scarce data bank on crude oil Doseresponse Assessment on plankton species in Nigeria, demonstrating that influx of crude oil into the Nigerian coastal waters is a risk factor to ecological status