Comments on Toxic marine microalgae and shellfish poisoning in the British isles: history, review of epidemiology, and future implications
Stephanie Hinder, Swansea Univeristy
13 April 2012
Re: Toxic marine microalgae and shellfish poisoning in the British isles: history, review of epidemiology, and future implications.
We would like to provide the following comments on the above paper, in order to provide additional and more up to date information and to correct some inaccuracies in the original publication.
First, in Table 1, we note that there are no known human cases of poisoning due to PTXs or YTXs, and only limited information exists from experimental animal studies. Further, these toxins should not be classified with the DSP toxin group. Neither have been shown to cause diarrhetic effects (Dominguez et al., 2010, Tubaro et al., 2010). While PTXs are often found in shellfish in combination with DSP toxins and maximum permitted levels for PTXs are set together with the DSP toxin group under the EC Regulation 853/2004, it was demonstrated by Miles et al. (2004) [53] that PTXs do not have a diarrhetic effect and they are no longer considered to be a part of the DSP group of toxins. YTXs do not share the same mode of action as the DSP toxin group and maximum permitted levels for YTXs are set independently under the EC Regulation 853/2004. Also in Table 1, the toxin associated with some species of Pseudo-nitzschia should read as `domoic¿ acid (page 6, paragraph 5, Table 1, and List of Abbreviations page 10).
We also note that European Council Directives 91/492/EEC and 91/493/EEC (described in Table 3) have been replaced, since 2006, by EC 853/2004. This regulation sets down health standards including maximum permitted levels for biotoxins for LBMs, live echinoderms, live tunicates and live marine gastropods. Liquid Chromatography using Mass Spectrometry (LC-MS) is now a reference method for the detection of lipophilic toxins (EU Regulation 15/2011, amending EC 2074/2005).
In Table 3, the limits for PSP and OA-group of toxins should be 800 ¿g/kg and 160 ¿g/kg respectively, measured in whole body or any part edible separately. In addition, on page 2 paragraph 5, the EU procedure following detection of toxins above the maximum regulatory limits is temporary closure of the bed until two consecutive samples taken at least 48hrs apart and testing below the maximum regulatory levels. In practice in the UK, this can effectively result in the closure period of two weeks, as described in the paper, as samples would normally be taken a week apart. We also note that not all species within each genera listed in table 3 are toxic.
Last, we can provide additional information on the 2008 outbreak in the Shetland Islands. 13 areas were affected between April and October (Table 7), however the outbreak was not continuous and concurrent between these areas. Across the region, harvesting areas were closed and re-opened at various points during the 8 month period. Similarly, Loch Tarbert in Argyll and Bute experienced several toxic episodes of DSP (16 positive results) throughout the year (between April 2008 and February 2009), but the area was not continually closed for 11 months, being re-opened for harvesting at several times during this period.
Stephanie Hinder (Institute of Life Science, Swansea University)
March 2012
References:
Dominguez HJ, Paz B, Daranas AH, Norte M, Franco JM, and Fernández JJ. 2010. Dinoflagellate polyether within the yessotoxin, pectenotoxin and okadaic acid toxin groups: characterization, analysis and human health implications. Toxicon 56(2), 191-217.
Tubaro A, Dell'ovo V, Sosa S, and Florio C. 2010. Yessotoxins: a toxicological overview. Toxicon 56(2), 163-172.
Acknowledgements
Thanks to Kasia Kazimierczak at the Food Standards Agency for comments, and help in clarifying several of these issues
Environmental Health
Comments on Toxic marine microalgae and shellfish poisoning in the British isles: history, review of epidemiology, and future implications
13 April 2012
Re: Toxic marine microalgae and shellfish poisoning in the British isles: history, review of epidemiology, and future implications.
We would like to provide the following comments on the above paper, in order to provide additional and more up to date information and to correct some inaccuracies in the original publication.
First, in Table 1, we note that there are no known human cases of poisoning due to PTXs or YTXs, and only limited information exists from experimental animal studies. Further, these toxins should not be classified with the DSP toxin group. Neither have been shown to cause diarrhetic effects (Dominguez et al., 2010, Tubaro et al., 2010). While PTXs are often found in shellfish in combination with DSP toxins and maximum permitted levels for PTXs are set together with the DSP toxin group under the EC Regulation 853/2004, it was demonstrated by Miles et al. (2004) [53] that PTXs do not have a diarrhetic effect and they are no longer considered to be a part of the DSP group of toxins. YTXs do not share the same mode of action as the DSP toxin group and maximum permitted levels for YTXs are set independently under the EC Regulation 853/2004. Also in Table 1, the toxin associated with some species of Pseudo-nitzschia should read as `domoic¿ acid (page 6, paragraph 5, Table 1, and List of Abbreviations page 10).
With regard to UK Monitoring procedures, for clarification (see page 2 paragraph 5) all groups of toxins (PSP, ASP, OA/DTXs, PTXs, AZAs and YTXs) are included in the biotoxin monitoring programmes in all countries of the UK (http://www.food.gov.uk/foodindustry/farmingfood/shellfish/). The Food Standard Agency (FSA) is not itself a National Reference Library (NRL) (page 2 paragraph 5 of the manuscript), but rather it funds the work of a group of various NRL¿s including an NRL on Biotoxins in Live Bivalve Mollusc (LBMs), which is currently undertaken by the Agri-Food and Biosciences Institute in Belfast (http://www.afbini.gov.uk/index/services/services-diagnostic-and-analytical/marine-biotoxins-nrl.htm). In addition, biotoxin monitoring programmes in England and Wales, Scotland and Northern Ireland apply different frequencies of sampling for biotoxin testing (http://www.food.gov.uk/foodindustry/farmingfood/shellfish/algaltoxin/, http://www.food.gov.uk/foodindustry/farmingfood/shellfish/nibiotoxin/,http://www.food.gov.uk/foodindustry/farmingfood/shellfish/ewbiotoxin/). Testing of LBMs for biotoxins monitoring purposes in Northern Ireland has now moved from DARD (page 2, paragraph 7) and is conducted by the Agri-Food and Biosciences Institute.
We also note that European Council Directives 91/492/EEC and 91/493/EEC (described in Table 3) have been replaced, since 2006, by EC 853/2004. This regulation sets down health standards including maximum permitted levels for biotoxins for LBMs, live echinoderms, live tunicates and live marine gastropods. Liquid Chromatography using Mass Spectrometry (LC-MS) is now a reference method for the detection of lipophilic toxins (EU Regulation 15/2011, amending EC 2074/2005).
In Table 3, the limits for PSP and OA-group of toxins should be 800 ¿g/kg and 160 ¿g/kg respectively, measured in whole body or any part edible separately. In addition, on page 2 paragraph 5, the EU procedure following detection of toxins above the maximum regulatory limits is temporary closure of the bed until two consecutive samples taken at least 48hrs apart and testing below the maximum regulatory levels. In practice in the UK, this can effectively result in the closure period of two weeks, as described in the paper, as samples would normally be taken a week apart. We also note that not all species within each genera listed in table 3 are toxic.
Last, we can provide additional information on the 2008 outbreak in the Shetland Islands. 13 areas were affected between April and October (Table 7), however the outbreak was not continuous and concurrent between these areas. Across the region, harvesting areas were closed and re-opened at various points during the 8 month period. Similarly, Loch Tarbert in Argyll and Bute experienced several toxic episodes of DSP (16 positive results) throughout the year (between April 2008 and February 2009), but the area was not continually closed for 11 months, being re-opened for harvesting at several times during this period.
Stephanie Hinder (Institute of Life Science, Swansea University)
March 2012
References:
Dominguez HJ, Paz B, Daranas AH, Norte M, Franco JM, and Fernández JJ. 2010. Dinoflagellate polyether within the yessotoxin, pectenotoxin and okadaic acid toxin groups: characterization, analysis and human health implications. Toxicon 56(2), 191-217.
Tubaro A, Dell'ovo V, Sosa S, and Florio C. 2010. Yessotoxins: a toxicological overview. Toxicon 56(2), 163-172.
Acknowledgements
Thanks to Kasia Kazimierczak at the Food Standards Agency for comments, and help in clarifying several of these issues
Competing interests
None declared