Presentation on theme: "Toxins as Weapons of Mass Destruction Esequiel Barrera, SM (TOX) Biol/Chem Safety Officer UTSWMC at Dallas."— Presentation transcript:
Toxins as Weapons of Mass Destruction Esequiel Barrera, SM (TOX) Biol/Chem Safety Officer UTSWMC at Dallas
Objectives Examples of toxins potential to be used as a Weapon of Mass Destruction (WMD) Ricin T-2 Mycotoxins
RICIN OVERVIEW Cytotoxin extracted from Castor Bean (Ricinus communis plant) Protein has a molecular weight 64,000 daltons Worldwide one million tons of castor beans are processed annually in the production of castor oil (waste mash is ~5% ricin by weight) Cancer and autoimmune treatment applications
History and Significance Assassination of Bulgarian exile Georgi Markov in London (1978) Minnesota Patriots Council (1994 and 1995) Deborah Green, Kansas (1995) Thomas Leahy, Wisconsin (1997) al Qaeda cell, London (2003)
Toxicology Potent protein and DNA synthesis inhibitor LD50 for mice is 3.0 ug/kg Comparative lethality: LD50 for Botulinum toxin (bacterium) is 0.001 and for VX gas (chemical agent) is 15.0 LD50 for humans is uncertain and varies with route of entry (ricin vs ricinine)
Agent Characteristics Ricin is environmentally stable with 3 day survival in dry conditions No person to person transmission Lethality is high with death occurring 10-12 days for ricin ingestion and 3-4 days for inhalational exposure
Identification Gold Standard technique is enzyme linked immunosorbent assays (ELISA) -antigen detection -IgG immunoassay -IgM immunoassay
Prophylaxis There is currently no commercial vaccine or prophylactic antitoxin available for human use albeit animal immunization studies have been promising Protective mask and engineering controls are currently the best protection
Inhalational ricin exposure: Signs and Symptoms 4 to 8 hours: Acute onset of fever, chest tightness, cough, dyspnea, nausea and arthralgias 18-24 hours: Airway necrosis and pulmonary capillary leak leading to pulmonary edema 36-72 hours: severe respiratory distress and death from hypoxemia
Medical Sampling Early Post-exposure (0-24 h): nasal swabs, induced respiratory secretions for PCR (contaminating castor bean DNA) and Serum for toxin assays Clinical (36-48 h): serum for toxin assay and tissues for immunohistological stain in pathology samples Postmortem (>6 days): Serum for IgM and IgG
Treatment Ingestional entry: Gastric lavage and cathartics are indicated. Charcoal application is of little value for large molecules such as ricin Inhalation entry: Pulmonary edema treatment and supportive management
Decontamination Ricin inactivation can be accomplished with bleach (1% sodium hypochlorite, 20 min) or autoclave treatment (80C for 10 min) Intact skin surface decontamination use soap and water (dilution).
T-2 MYCOTOXINS OVERVIEW Trichothecene (T-2) mycotoxins produced by the fungi of genus Fusarium (common grain mold) Extremely stable in the environment Toxin is dermally active causing blisters (minutes to hours after exposure)
History and Significance Shortly after WWII, flour contaminated with Fusarium unknowingly baked into bread and ingested by civilians. Exposed individuals developed a protracted lethal illness called alimentary toxic aleukia (ATA). Yellow rain incidents in Laos (1975-81), Kampuchea (1979-81) and Afghanistan (1979-81).
Toxin Characteristics Trichothecene are relatively insoluble in water Compounds are extremely stable to heat and ultraviolet light inactivation Bioactivity retained even after standard autoclaving (inactivation requires 1500 F for 30 minutes) Hypochlorite solution alone does not inactive the toxins Toxin rapidly inhibit protein and nucleic acid synthesis
Clinical Features Routes of exposure: penetration through the skin, inhalation and ingestion. Contaminated clothing can serve as a reservoir for further toxin exposure Early symptoms (minutes after skin exposure): burning skin, redness, tenderness, blistering and progression to skin necrosis with leathery blackening and sloughing of large areas of the skin Pulmonary/tracheobronchial toxicity produces dyspnea, wheezing and cough. Gastrointestinal toxicity causes pain and blood tinged saliva and sputum Death may occur in minutes, hours or days Most common symptoms: vomiting, diarrhea, skin involvement with burning pain, redness, rash or blisters, bleeding and dyspnea.
DIAGNOSIS Physical clues yellow, red, green or other pigmented oily liquid Contact with the skin (unlike ricin) forms characteristic symptoms Generally considered odorless (unlike mustard or other vesicant agents) Serum and urine should be collected to be sent to a reference lab for antigen detection (gas liquid chromatography-mass spectrometry technique)
MEDICAL TREATMENT Toxin inactivation requires 0.1M NaOH added to 1% hypochlorite solution for a duration of one hour. No specific antidote or therapeutic regimen is currently available. Exposed individuals: remove clothing, wash skin with soap and water. Standard burn care is indicated for cutaneous involvement Toxin ingestion use superactivated charcoal Aerosol attack: respiratory support may be required, rinse out eyes with saline or water. Prophylaxis: only physical protection of the skin, mucous membranes and airway are the only proven effective methods of protection during an attack.