Answers to Often-Asked Questions
PROTECTING HEALTH-CARE PROVIDERS
For the same reason that decontamination is only moderately importantafter personnel are exposed to a respirable toxin aerosol, health-careproviders are probably at only limited risk from secondary aerosols.Because toxins are not volatile, casualties can, for the mostpart, be handled safely and moved into closed spaces or buildings,unless they were very heavily exposed. Prudence dictates, however,that patients be handled as chemical casualties or, at a minimum,that they be washed with soap and water. The risk to health-careproviders is of greater concern with some agents. Secondary exposuremight be a hazard with very potent bacterial protein toxins, suchas botulinum toxin or the staphylococcal enterotoxins. (Note thatdecontamination and isolation of patients or remains could bemuch more important and difficult after an attack with a bacteriaor virus that replicates within the body.)
Remains of persons possibly contaminated with toxins should behandled as chemically contaminated remains. For the most part,toxins are more easily destroyed than chemical agents, and theyare much more easily destroyed than spores of anthrax. Chemicaldisinfection of remains in 0.2% sodium hypochlorite solution for10 minutes would destroy all surface toxin (and even anthrax spores),greatly reducing the risk of secondary exposure.
SAMPLE COLLECTION: General Rules for Toxins
Identifying toxins or their metabolites (break-down products)in biological samples (blood, urine, feces, saliva or body tissues)is difficult for several reasons. In the case of the most toxictoxins, relatively few molecules of toxin need be present in thebody to cause an effect, therefore, "finding" them requiresextremely sensitive assays. Secondly, the most toxic, and mostlikely to be seen on the battlefield, are proteins, a class ofmolecules which our bodies break down and process. Therefore,these toxins and pieces of them after breakdown often "blendinto the scenery" of the body and, at some point, are nolonger identifiable.
Typically, we must look for the toxin itself or its metabolites,not an antibody response, as can be done with infectious agents.It is very unlikely that anyone receiving a lethal dose of anyof the toxins would live long enough to be able to mount an antibodyresponse. However, with certain protein toxins (ricin and thestaphylococcal enterotoxins) that are highly immunogenic and lesslethal, one might expect to see antibodies produced in soldierswho received a single exposure and survived. These might be seenas early as two weeks after exposure.
Certain toxins can be identified in the serum of animals, thereforeprobably humans, exposed by inhalation. Blood samples should becollected in sterile tubes and kept frozen, or at least cold,preferably after clotting and removal of cells. If collected withinthe first day, swab samples taken from the nasal mucosa may beuseful in identifying several of the toxins. These too, shouldbe kept cold. As a general rule, all samples that are allowedto remain at room temperature (approximately 75-80°F) orabove for any length of time will have little value.
Biological samples from patients are generally not as useful fordiagnosis of intoxications as they ar for diagnosis of infectiousdiseases. The same is true of postmortem samples. The literaturesuggests that botulinum toxins can be isolated from liver andspleen, even when they cannot be isolated from blood. We can identifyricin with immunoassays in extracts of lung, liver, stomach andintestines up to 24 hours after aerosol exposure. We have identifiedhigh doses of ricin in fixed lung tissue of aerosol-exposed laboratoryanimals by immunohistochemical methods. The staphylococcal enterotoxinscan be detected by immunoassay in bronchial washes. Like bloodand swab samples, postmortem tissue or fluid samples should bekept cold, preferably frozen, until they can be assayed.
Environmental samples from munitions or swabs from environmentalmaterials should be placed in sealed glass or Teflon~ containers,and kept dry and as cold as possible. Handling a dry or powderedtoxin can be very dangerous, because the toxin may adhere to skinand clothing and could be inhaled.
TOXIN ANALYSIS AND IDENTIFICATION
Immunological and/or analytical assays are available for mostof the toxins discussed in this document. Immunological methods,typically enzyme-linked immunosorbent assays (ELISA) or receptorbindingassays, are sensitive to 1-10 nanograms/milliliter and requireapproximately 4 hours to complete; these are being developed asthe definitive diagnostic tests for deployment. Analytical (chemical)methods are sensitive at low microgram to high nanogram amounts,and take approximately 2 hours to run, plus time for instrumentsetup and isolation or matrix removal when necessary; the lattercan add days to the process. A small, sensitive, far-forward,fieldable assay for several toxins has been developed and similarkit assays are being developed for many of the other toxins describedin this document. The polymerase chain reaction (PCR) technique,which provides very sensitive means of detecting and identifyingthe genetic material (DNA) of any living organism, can be usedto detect remnants of the bacterial, plant or animal cells thatmight remain in the crude, impure toxin one would expect to findin a weapon. Finally, a new method of combining immunoassays withPCR may allow us to detect extremely small quantities of the toxinsthemselves. In their present state, PCR assays are primarily suitedfor use in the reference laboratory.
Questions often arise regarding the protection of water suppliesfrom toxins. It is unlikely that a typical small-particle aerosolattack with toxins would significantly contaminate water supplies.Furthermore, as a general rule, direct contamination of watersupplies by pouring toxins into the water would require that itbe done downstream of the processing plant and near the end user,even for the most toxic bacterial toxins-and normal chlorinationmethods are effective against some of the most potent toxins.Because of dilution, adding toxins to a lake or reservoir wouldbe unlikely to cause human illness. Natural production of algaltoxins (e.g., microcystin) in stagnant bodies of water could produceenough toxin to cause illness if that water were used for drinking.The following methods of water purification have been tested forthe toxins listed.
Reverse osmosis systems are effective against:
- Ricin-64,000 daltons (molecular weight)
- Microcystin-1,000 daltons
- T-2-466 daltons
- Saxitoxin-294 daltons
- (Botulinum toxin-150,000 daltons and SEB-28,494 daltons not tested:expect same result)
Not effective for removing ricin, microcystin, T-2 or saxitoxinfrom water.
Five milligrams/liter (5 parts per million) free, available chlorine(household bleach) for 30 minutes destroys botulinum toxin. Thisconcentration does not inactivate ricin, microcystin, T-2 or saxitoxin.
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