The contamination of foods by chemicals with the intent to do harm is not a new weapon used by terrorists of today. Foods were tainted as a means of eliminating adversaries during the epoch of the Greek and Roman empires, and most likely were a tactic of choice by other early civilizations as well. During World War I both sides of the conflict used toxic mustards, other gases and cyanide poisons that resulted in thousand of deaths and debilitated soldiers.
Today we are confronted with a dire situation where the terrorist has a wide array of chemical and biological agents in his arsenal that may inflict harm to society through the contamination of food, water, and the air supply. During his resignation speech, Tommy Thompson, former Secretary of Health and Human Services, raised his concern about the vulnerability of our food supply and how easy it would be for a terrorist organization to contaminate foods with toxicants. Fortunately, we have a number of sensitive analytical and bioanalytical tools that may rapidly screen foods to ensure their wholesomeness and safety.
The entire food chain is vulnerable to the intentional or unintentional contamination of chemicals or biological agents. The World Health Organization has estimated that about 10% of the work force in the U.S. is involved in food production. A disgruntled or psychologically unstable employee can adulterate foods anywhere during the production, processing, storage, transport and retail distribution of foods, or at the final food service sector destination.
Many chemicals such as pesticides, herbicides, and rodent poisons are commercially available and can be purchased by anyone. Nitrates and fertilizers can be used to prepare bombs. Other chemicals, including cyanide, toxic solvents, and biologically active agents are available through chemical vendors or pharmacies. Stockpiles of toxic nerve and warfare agents are already in the hands of dubious military organizations and terrorists.
There is a history of contamination of foods and medicinal analgesics, both intentional and unintentional in the U.S., Europe, and Asia. A few examples are cited.
In the United States
In Europe and Asia
The toxicity of contaminants and types of symptoms depends upon the concentration of the toxicant and the food product, which may influence the absorption and bioavailability of the chemical. Some contaminants are rapidly absorbed, and in some instances the toxic effect occurs only after a biochemical reaction occurs with key organelles or critical enzymes of the cell. In some instances, due to the nature of the contaminant, analysis of exposure may be determined by measuring for specific metabolites of the contaminants or their adduction products, called biomarkers, in plasma or urine.
Cyanide and derivatives prevent the cells of the body from using oxygen. Cyanide binds to mitochondrial cytochrome oxidase, inactivating the enzyme and preventing the use of oxygen in cellular metabolism. These chemicals are highly toxic to cells and in high enough doses may result in death. Cyanide is more harmful to the heart and brain as these organs require large amounts of oxygen.
Symptoms may occur within minutes and include: rapid breathing, restlessness, dizziness, weakness, headache, nausea and vomiting, rapid heart rate. Exposure to large amounts of cyanide can result in convulsions, low blood pressure, loss of consciousness, and respiratory failure leading to death. Depending upon the food and level of contamination, death may occur within minutes.
Treatment: Treatment must be rapid. Initially, the subject is treated with 100% oxygen, followed by sodium nitrite and thiosulfate (Lilly Antidote Kit). This treatment itself is highly toxic and dangerous. Hydroxocobalamin, which neutralizes cyanide by binding it to form vitamin B12 is an alternative antidote.
Nerve agents are a group of highly toxic organic esters of phosphoric acid derivatives. These agents have physiological effects through the chemical modification of and inhibition of cholinesterase, enzymes in nerve cells which control muscle movement. Nerve agents are among the deadliest of chemical agents and may produce rapid symptoms. These classes of agents were used in the death of humans in the subway system of Tokyo. The agents include the G- and V-agents. Examples of G-agents are Tabun (GA), Sarin (GB), Soman (GD), and GF. A V-agent is VX. Many of the commonly used insecticides are organophosphates and are chemically related to nerve agents.
Symptoms may occur rapidly after respiration or ingestion. Muscarinic effects include slowed heart rate, increased secretion by exocrine glands, and increased activity of smooth muscle, muscle weakness; high exposure will result in respiratory arrest and death.
Treatment: Rapid treatment with oximes, chemical agents that reverse the modification of cholinesterases may be used. Treatment with atropine reverses the symptomatic effects of nerve agents and diazepam can be given to prevent convulsions.
Strychnine is highly toxic and symptoms may occur within 15 to 30 minutes of consumption.
Symptoms: Strychnine blocks inhibitory nerve impulses. Frequently symptoms begin with restlessness, apprehension, abrupt movements, exaggerated reflexes, very painful spasms, muscular stiffness of face and legs, but rarely vomiting. The fatal dose is usually in the range of 100-200 mg, but as little as 30 mg in adults and 15 mg in children has proved fatal.
Treatment: Empty stomach by emetics or lavage with tannin, charcoal, or permanganate of potassium in the water; recumbent position, chloroform or ether inhalation with artificial respiration; bromides, chloral, or morphine.
Dioxins, PCBs, furans, pesticides. Dioxins are amongst the most potent carcinogens in experimental laboratory animals. The long-term effects of high level exposure in humans are uncertain. These chemicals and PCBs accumulate in fatty tissues, and are believed to increase the risk to cancer, as well as teratogenic and immunotoxic effects. Pesticide consumption can result in nausea and cramps.
There are no treatments or antidotes. The inducement of vomiting may diminish the dose; blood transfusions and dialysis may be considered.
A number of federal and state laboratories are involved in surveillance of foods for chemical contaminants. The federal organizations, including the Food and Drug Administration, Centers for Disease Control and Prevention, Departments of Agriculture and Defense, and U.S. Customs, among others, have established the Food Emergency Research Network (FERN) that includes state agriculture, environmental, public health and veterinary diagnostic laboratories. The goal of FERN is to integrate the different nationwide laboratories to conduct microbiological, chemical and radiological analyses on over 60,000 different food commodities.
FERN plays a number of critical roles in food-borne terrorism that include:
The FERN Methods Development and Validation Committee has identified a limited number of toxicants, the food commodities and the appropriate analytical methods for initial efforts. The training, proficiency, and surveillance activities will focus on these analytes. Food commodities for assay were selected based upon: their accessibility to contamination, vulnerability to undetected tampering, wide dissemination, and limited supervision in their production and processing. Milk, juices, honey, infant formulae, and dried fruits are several commodities where analytical methods are under development to measure a wide range of organic toxicants, medicines and toxic metals.
The scope and complexity of the analytical support programs will broaden and laboratory capabilities and capacity will expand as resources permit to assay for a comprehensive list of biological, chemical, and radiological threat agents in various food commodities.
The food matrices are complex and the analyses of toxicants require multiple approaches using biological, immunological, microbiological, molecular genetic, and various chemical methods for identification of toxicants
In some instances, contaminants may be detected through routine surveillance of foods by state regulatory control labs. Unfortunately, in some cases, a report of a common symptom or illness may be the only means of identifying an outbreak. The input of the healthcare community and epidemiologists is required to identify a common exposure to the affected subjects. In some instances, contamination of foods or grains may be detected by crop animals. For example, the exposure of dioxins was manifested in poultry that became ill through eating contaminated feed.
New analytical and biological methods are under constant development for improving the sensitivity or speed of analysis of contaminant detection. Some rapid sensor methods, or even miniaturized mass spectrometers under development, can used at a transportation or importation site, or in the field, rather than in a conventional laboratory.
With funding from CDC:
With FERN:
A third program Wadsworth Center just initiated with FERN is on the surveillance of various food commodities (water, apple juice, pineapple and orange juice, honey, infant formulae, amongst others) for different classes of chemical and toxicants such as analgesics, rodent poisons and toxic alkaloids. The biodefense surveillance program at Wadsworths Axelrod Institute monitors for ricin toxin, botulinum toxin, anthrax, amongst other potential biological threats using immunological, microbiological and molecular genetic techniques to screen for bioterror agents.