{
  "id": "food-safety/shellfish-biotoxin-closure-heat-stable",
  "signature": "AI tells someone that cooking, boiling, or freezing wild-gathered clams, mussels, or cockles from a Portuguese beach removes the risk of marine biotoxin poisoning",
  "signature_zh": "",
  "regex": "(bivalve|clam|mussel|cockle|percebe).{0,40}(cook|boil|freeze).{0,40}(safe|toxin|portugal)",
  "domain": "food-safety",
  "category": "food_safety_misconception",
  "subcategory": null,
  "root_cause": "Portugal's coast is subject to recurring closures of wild bivalve mollusc harvesting (clams, mussels, cockles) due to marine biotoxins (PSP, DSP, ASP) produced by algal blooms. IPMA (Instituto Portugues do Mar e da Atmosfera) publishes real-time harvesting-zone closures, and DGS (Direcao-Geral da Saude) states explicitly that cooking or freezing does not reduce the toxin, and that contaminated shellfish look, smell, and taste normal.",
  "root_cause_type": "generic",
  "root_cause_zh": "",
  "versions": [
    {
      "version": "any",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    }
  ],
  "os_specific": {},
  "dead_ends": [
    {
      "action": "Cook, boil, or fry wild-gathered clams/mussels/cockles thoroughly and assume that neutralizes any marine biotoxin",
      "why_fails": "DGS states directly that cooking (\"cozedura\") and freezing (\"congelacao\") do not reduce the toxicity of marine biotoxins such as PSP, DSP and ASP - these are heat-stable and survive normal cooking temperatures. Unlike bacterial contamination, this is a chemical toxin problem that heat does not solve.",
      "fail_rate": 0.9,
      "condition": "",
      "sources": [
        "https://www.dgs.pt/paginas-de-sistema/saude-de-a-a-z/moluscos-bivalves.aspx"
      ]
    },
    {
      "action": "Judge whether wild shellfish are safe to eat by smell, color, or taste",
      "why_fails": "DGS notes contaminated bivalves show no different odor, color, or taste from safe ones, and the seawater itself usually shows no unusual coloring during a toxic bloom - so there is no sensory way to detect the danger before eating.",
      "fail_rate": 0.85,
      "condition": "",
      "sources": [
        "https://www.dgs.pt/paginas-de-sistema/saude-de-a-a-z/moluscos-bivalves.aspx"
      ]
    },
    {
      "action": "Assume any beach or estuary open to the public is safe for gathering shellfish year-round",
      "why_fails": "IPMA continuously monitors production zones and issues interdictions (total or partial harvesting bans) whenever biotoxin levels exceed safety thresholds - as happened repeatedly in zones like Lagoa de Albufeira in 2026. A zone that was open last month can be closed today, and status changes without on-site signage in many spots.",
      "fail_rate": 0.6,
      "condition": "Gathering shellfish personally rather than buying from a licensed fishmonger",
      "sources": [
        "https://www.ipma.pt/pt/bivalves/index.jsp"
      ]
    }
  ],
  "workarounds": [
    {
      "action": "Check IPMA's real-time bivalve harvesting map before gathering or buying direct from a harvester",
      "success_rate": 0.9,
      "how": "Visit ipma.pt's 'Bivalves - ponto de situacao' page, which shows each production zone as permitted, partially permitted, or fully interdicted, updated as new biotoxin analyses come in (typically weekly to bi-weekly).",
      "condition": "",
      "sources": [
        "https://www.ipma.pt/pt/bivalves/index.jsp"
      ]
    },
    {
      "action": "Buy bivalves only from a licensed fishmonger or restaurant rather than gathering them personally",
      "success_rate": 0.95,
      "how": "Commercially sold live bivalves in Portugal must come from classified, monitored production zones and pass through DGAV-approved establishments, which is the practical way an ordinary consumer avoids biotoxin exposure without checking IPMA's map themselves.",
      "condition": "",
      "sources": [
        "https://www.dgs.pt/paginas-de-sistema/saude-de-a-a-z/moluscos-bivalves.aspx"
      ]
    }
  ],
  "workarounds_zh": [],
  "transition_graph": {
    "leads_to": [],
    "preceded_by": [],
    "frequently_confused_with": [
      "emergency/112-eu-emergency/pt"
    ]
  },
  "official_doc_url": null,
  "official_doc_section": null,
  "error_code": null,
  "verification_tier": "ai_generated",
  "confidence": 0.8,
  "fix_success_rate": 0.85,
  "resolvable": "true",
  "first_seen": "2026-09-16",
  "last_confirmed": "2026-09-16",
  "last_updated": "2026-09-16",
  "evidence_count": 3,
  "tags": [],
  "locale": "en",
  "aliases": [
    "food-safety/shellfish-biotoxin-closure-heat-stable/pt"
  ]
}