Environmental Mimics of Chemical Warfare Agents

Military Medicine, Dec 2004 by Claborn, David M

There are several natural and artificial factors that mimic the effects of chemical warfare agents, thereby causing unwarranted alarm and confusion on the battlefield. Symptoms associated with chemical warfare include paralysis, muscle tremors, heavy salivation, severe burns, blistering, and corrosive skin injuries among others. Similar symptoms can be produced from a variety of environmental sources, artificial and natural. This article reviews several published and unpublished examples of environmental factors that produce syndromes similar to those caused by these agents. Examples of such mimics include pesticides, blistering exudates from insects and plants, various types of bites, and naturally occurring diseases. The potential for confusion caused by these factors is discussed and means of discriminating between warfare agents and naturally occurring events are identified. Recommendations for the use of this information and for needed research are also discussed.

Introduction

In 1997, several U.S. Marines on an exercise in central Arizona experienced severe blistering symptoms. Several individuals exhibited very large blisters on their legs, arms, and faces, and another victim developed a severe case of conjunctivitis in one eye. Military medical personnel could not identify the source of the outbreak. However, because the Marines did not appear to be in distress, most of the victims were returned to duty. Interestingly, the appearance of the blisters reminded the Marines of images they had seen during training sessions on chemical warfare. Fearing possible exposure to blistering agents, some Marines, including at least one company grade officer, were dissatisfied with their medical treatment and threatened to seek civilian medical care in the nearest city.

A subsequent investigation by U.S. Navy preventive medicine personnel identified the probable cause of the blistering disease as a small rove beetle (family: Staphylinidae) which exudes a strong blistering agent when disturbed.1 These beetles had probably been flooded out of their normal rodent-burrow habitats by unusually heavy rains and were attracted to the lights of the Marine encampment. As the beetles brushed against the humans, the resulting slap stimulated the insects to exude blistering agent, causing the large blebs and the conjunctivitis noted in the blistering disease. The outbreak ended a few days after the last heavy rain. The Marines had in effect suffered a chemical attack, although the attack was not human in origin.

Although limited in scope, this episode is of interest because of the response of the Marines to the perceived threat of chemical warfare. It demonstrates the confusion and alarm that ensues when military personnel cannot distinguish between the symptoms caused by chemical warfare agents and similar symptoms caused by common environmental factors. These environmental factors are "mimics" of chemical warfare agents.

During the blistering disease incident in Arizona, where there was no credible threat of a chemical warfare agent, it took several weeks to find a probable cause. A definite cause was never identified. The alarm among the Marines was significant, but in a real wartime scenario, the confusion could be much worse. One potential way of reducing such confusion would be the identification of common mimics of chemical warfare agents

before arrival in the area of operations. If such knowledge was available, medical personnel would be better able to discriminate between indigenous maladies and the emergencies caused by intentional use of warfare agents. As the Arizona incident demonstrates, nonmedical personnel can also benefit from this knowledge.

On the other hand, such information might delay proper treatment for chemical agent victims. Indeed, the speed with which medical personnel obtain proper diagnosis and the rapidity with which they apply proper therapeutic measures can greatly influence mortality rates after a chemical attack.2 Conversely, false alarms can also degrade a unit's war-fighting capabilities. The defensive measures used by the U.S. military on the chemical battlefield are effective, but they are also very risky and are likely to impair performance and decision making.3 For example, Headly4 noted that antidotal atropine increases skin and rectal temperature and compromises thermoregulation, especially in soldiers wearing protective clothing or working in hot environments.

Unnecessary alerts might also result in the wasteful employment of limited protective gear, requiring rapid replenishment to deployed units. This situation would be particularly important in a war zone where supply lines can be extended and unreliable.

Weiner5 stated that to implement a successful chemical/biological defense response, the following three questions must be answered: (1) How do we know the outbreak of a disease or malady is a chemical/biological attack and not a natural epidemic? (2) What agents are being used by hostile forces? (3) What countermeasures are available?