Since the inception in 1991 of federal programs to investigate the health concerns of Gulf War veterans, there has been a growing realization that troops deployed to the Gulf could have encountered a number of different service- related exposures with potential to cause health effects. One such exposure was to pesticides
Note: There is no evidence to support the supposition that veterans feared health effects from pesticides prior to or during Gulf War service. Health concerns expressed by veterans after the Gulf War are almost certainly not based on pre-war fears or suspicions of potential health effects from pesticides. Rather the opposite may be true: Pesticide use in the Gulf was intended to *protect* health, not put it at risk, and it is probable that the troops understood this intention and believed in it. The troops *were* instructed to use DEET on their persons, and to treat their battledress uniforms with permethrin -- these measures were clearly intended to protect health. It is not incredible to suppose that the troops may have trusted in the protective capacity of pesticides without any regard whatsoever to the harm pesticides could cause. At the time of the Gulf War, it is more than likely that the troops regarded pesticides with trust rather than with suspicion.
More than DEET and permethrin
Many people are *now* aware that troops in the Gulf were exposed to the synthetic pyrethroid insecticide permethrin in their uniforms, and to the insect repellent DEET. What many people-- including some veterans-- do *not* realize is that troop pesticide exposures may well have been far more varied-- and potentially far more hazardous--than most people think.
Troop field deployment in the Gulf region involved a substantial risk of insect-borne diseases, such as malaria, dengue, and leishmaniasis, among others. Less-than-ideal conditions prevail when troops are deployed, so insect control in the field was dependent on pesticide use
Although protection against insect-borne disease was sought from pesticide use, the pesticides used were themselves known to pose risks to human health-- some of them the same risks posed by nerve agents used in chemical weapons. It is not clear that the troops were ever informed of this, or if they knew that the pesticides that they themselves used, and that others used in the field, were hazardous.
Certainly US civilian attitudes toward pesticide use tend to be somewhat casual: In a survey of US households, EPA found that though over 80 percent of all households possess pesticide products, fewer than half of those questioned read pesticide product labels, took precautions to guard health, or even were aware of pesticide- related health risks. Such attitudes toward pesticides may have been prevalent among troops serving in the Gulf. It is not known whether troops were instructed about the hazards of pesticides, or about how to reduce their risks during use.
In addition to the pesticides used by the troops (permethrin and DEET), other pesticides were also approved for use in the Gulf. These include carbamate and organophosphate insecticides, coumarin rat poisons, pyrethroid insecticides in addition to permethrin, and a persistent organochlorine pesticide (lindane). The general activity and related health effects of these pesticides are known, but it is *not* known to what extent these pesticides were used in the Gulf, who used them, for what purpose, how, or--most important--who was exposed to them, and what safeguards were used to limit exposure.
Types of pesticides approved for US military use in the Gulf, and their health effects
The information that follows about which pesticides were used in the Gulf is based on information contained in R.R.Blanck et al., Unexplained illnesses among Desert Storm veterans: a search for causes, treatment, and cooperation. (Archives of Internal Medicine 155, 262- 268, February 13, 1995) and the Presidential Commission on Gulf War Veterans Illnesses, Final Report, January 1997. The information about the known health effects of each type of pesticide is drawn from D.P. Morgan (Recognition and Management of Pesticides Poisonings, 1989) and S.A. Briggs et al. (Basic Guide to Pesticides 1991). *Note* however, that not all effects ascribed to a particular type of pesticide listed are characteristic of all products containing that pesticide; nor are all people exposed to pesticides of any particular type equally apt to develop all (or indeed any) of the health effects associated with that type of pesticide.
*Note too* that effects ascribed below are associated with *active pesticide ingredients only*. Pesticide products frequently contain so-called inert (that is, non-pesticidal) ingredients, and some of these inerts have health effects of their own. In particular, pesticides delivered in solvents add to solvent exposure (which can itself be neurotoxic); pesticides delivered in aromatic hydrocarbons or petroleum distillates add to exposures to these substances as well as to pesticide exposures.
What this information *does* indicate is that there was potential for troops serving in the Gulf to have pesticide exposures that could have added greatly to the overall toxic burden of Gulf War service, and that some of the pesticides approved for military use have effects that could well have added to the toxicity of pyridostigmine bromide and/or nerve agent chemical weapons.
*****It is especially important to realize that all of the information that follows was readily available prior to Desert Storm/Desert Shield. Reliable and well documented information about the mode of action and toxicity of the pesticides approved for military use in the Gulf was freely available from many government sources.*****
Amide pesticide: DEET insect repellent. Acute effects of amides include skin irritation and sensitization, eye and respiratory irritation, nausea, headache, uncoordination, salivation, light sensitivity, tremor, muscle weakness. Long term effects include kidney, liver damage; irreversible eye damage; cardiovascular effects. Some amides are carcinogens, mutagens, immunotoxins. Exposure to DEET can be considered universal for US Gulf War troops.
Carbamates: bendiocarb, carbaryl, ficam, methomyl, propoxur. These insecticides inhibit the nervous system enzyme acetylcholine esterase. Acute symptoms of carbamate poisoning include sensory and behavioral disturbances, uncoordination, depressed motor function; malaise; muscle weakness;dizziness; salivation, nausea, abdominal pain, vomiting, diarrhea; slurred speech; blurred vision; muscle twitches, spasms; convulsions. Long term effects of carbamate exposure may include memory loss and behavioral defects. Carbamate pesticides are suspected of being mutagens and carcinogens; they may cause bone marrow, liver, and testicular damage. They are also suspected of enhancing the effects of viruses. Note: Bendiocarb, carbaryl and propoxur are commonly used in the US; they are among the pesticides most frequently used indoors, where people may have prolonged (and unwitting) contact with them.Thus US troop exposure to these pesticides prior to Gulf service is likely. It is not known what influence prior exposure to carbamate pesticides could have had on the effect service-related carbamate exposure; effects of repeated exposure may be cumulative over time. NOTE: The drug pyridostigmine bromide, also used in the Gulf, is also a carbamate compound known to inhibit acetylcholine esterase.
Organophosphates: chlorpyrifos, diazinon, fenitrothion, malathion. These insecticides also inhibit acetylcholine esterase, along with carbamate insecticides and pyridostigmine bromide. Acute effects of organophosphate pesticide exposure include behavioral disturbance, uncoordination, muscle twitching, headache, restlessness, sleep pattern change, tremor, confusion, incontinence, constricted pupils, memory loss, anxiety, irritability, confusion; nausea, abdominal cramps, diarrhea; slowed heartbeat, hypertension. Long term effects included delayed neurotoxicity, abnormal brain waves, destruction of myelin; decreases in auditory attention, visual memory, problem solving, balance and dexterity; persistent anorexia, weakness, malaise; eye damage; suppressed antibody formation, white blood cell destruction. Organophosphate pesticides have been linked to immunotoxicity, and are suspected of being carcinogens, mutagens, teratogens, and viral enhancers
Chlorpyrifos and diazinon are common home, garden and building maintenance pesticides, and many Americans--most likely including many Gulf War service personnel-- have been exposed to them. Effects of repeated exposures may be cumulative. Note that organophosphate pesticides represent one line of descent from the nerve gases synthesized after World War 1; modern chemical weapon nerve agents represent another line of descent from the same compounds.
Organophosphate pesticides have been implicated in both acute human poisonings and delayed effects in the human nervous system. In addition, isodiazinon, a contaminant that sometimes occurs in diazinon, has been associated with the metabolic condition porphyria. Porphyria often produces nervous system and other symptoms that are easily confused with other conditions; diagnosis of porphyria is confirmed by blood test.
Organochlorine: lindane. This pesticide is used to control head and body lice, among other uses. Authorized use in the Gulf is believed to have been limited, but actual use is not known. Acute effects of organochlorine exposure include rapid induction of drug metabolism; convulsions; hypersensitivity of skin, skin rash ; tremor, uncoordination; labored breathing; headache; hypertension; hyperthermia. Long-term effects: altered brain waves; damage to kidney, liver, testicular, eye, bladder, lung. thyroid, adrenal , bone marrow; aplastic anemia , porphyria cutanea tarda; carcinogens, teratogens, mutagens, fetotoxins, increased mortality in offspring. NOTE: many organochlorine pesticides have been banned in the US but continue to be available abroad. See below for discussion of pesticides *not* authorized for use in the Gulf. Note too that most people in the industrialized world carry traces of DDT and its metabolites in their bodies, and that ongoing exposures to one organochlorine pesticide--paradichlorobenzene--is still very common: this pesticide is the active ingredient in mothballs, some toilet cleaners, and was formerly common in “air freshener” products.
Coumarin: brodifcoum, bromadiolone. These rodent poisons work by interfering with blood clotting. Coumarin is used as a human drug, but it is a dangerous one that must be closely monitored in those taking it. Coumarin may cause hemorrhaging in the brain, as well as spontaneous bruising, bleeding gums, and blood in urine and feces.
Pyrethroids: cypermethrin, d-phenothrin, pyrethrin, in addition to permethrin. Although considered “safer” pesticides than organochlorine, organophosphate and carbamate pesticides, pyrethroid pesticides are acutely toxic if ingested (they are not thought to pass through intact skin), and can provoke allergy and asthma attacks in susceptible people, especially those allergic to ragweed. Some pyrethroid pesticides block nervous system transmission, producing effects resembling organochlorine exposure. In addition, some pyrethroid products contain chemicals to enhance their effectiveness, and the most commonly occurring such chemical, piperonyl butoxide, can intensify the effects of *other* pesticides encountered at the same time, and interfere with the metabolism of other chemicals in the liver by suppressing some liver functions.
How were pesticides used in the Gulf-- and by whom?
It is not clear who was responsible in the field for the selection, use and disposal of these materials. It *is* known that each US Army company-size unit is required by a 1989 Army regulation to have a Field Sanitation Team, "capable of implementing field preventive medicine activities beyond the individual soldier's scope." Pest control is one such "preventive medicine activity." But it is not clear how many army units deployed to the Gulf with Field Sanitation Teams.(It is also not clear what provision other service branches make for providing pest control in the field.) *After* the Gulf War, the majority of US army units deployed to Haiti went without required Field Sanitation Teams.
If army units deployed to the Gulf were similarly under-staffed, it is possible that pesticides were used in the Gulf without proper precautions. This could have exposed an unknown number of military personnel to hazardous materials without proper safeguards or sufficient information to alert the troops to the risks the pesticides posed.
To our knowledge, no one has asked about the deployment of Field Sanitation Teams in the Gulf, nor has anyone asked about who applied pesticides in army and other service units without such teams (if in fact there were units deployed in the Gulf without FSTs or the equivalent). To our knowledge, no one has examined the occupational descriptions or investigated the health of Field Sanitation Team personnel (as compared with personnel not assigned to FST's). Investigations into these matters could provide significant insight into the exposures encountered by troops deployed to the Gulf, or, alternatively, they could rule out these concerns as germane.
Little can be assumed about exposures to pesticides approved for military use in the Gulf (other than permethrin and DEET). So far, information about what was actually used, by whom and where, has not been published. Without this information, it is impossible to know what, if any, contribution pesticides have made to the health concerns of Gulf War veterans. It may be especially important to attempt to gather as much information about pesticide use in the Gulf as possible, not only because the chemicals themselves are capable of contributing to some of the symptoms being experienced by the veterans, but also because field conditions may have promoted accidental ingestion or other contact with pesticides. For instance, lack of access to water for handwashing may have contributed to the transfer of pesticides from hands to food and from food to mouth.
Several caveats to observe in interpreting this information
The assumption that US troops were exposed *only* to those pesticides approved for US military use may be unwarranted. It is known that some pesticide products were purchased locally and used in the Gulf. Accounts of such purchases indicate that product labels were in Arabic and that purchasers relied on local translators to facilitate selection and purchase of these products. Labels were not retained, nor were records kept, according to accounts published to date. It is worth noting that pesticides that have been banned in the US for both health and environmental reasons are readily available in s some places overseas. These include persistent organochlorine pesticides like DDT that have acute nervous system effects. Organochlorines can accumulate in body fat and be released during weight loss, at which time they may interact with other chemicals in the body
In addition, there have been accounts of pesticide product “sharing” among coalition forces deployed in the Gulf. It is possible that some US troops were exposed to pesticides authorized by other governments (but not by the US) with troops in the Gulf, or to unknown pesticides purchased by other coalition forces and “shared” with US troops. The extent of this practice is unknown and its effects (if any) will probably never be known.
The pesticide exposures troops encountered may not have been limited to those they applied themselves or that were applied by personnel in their own units. The Office of Technology Assessment pointed out in 1993 that environmental pesticides applied by one unit could still be active when troops in another unit arrived at that location. There evidently were no records kept of which units applied what pesticides and where, and units evidently did not report to each other what products were used prior to their move out of given areas. New pesticides applied by each unit in series during movements through territory could have resulted in substantial exposures for some troops, particularly exposures to organophosphate insecticides capable of persistence after application.
Personal use by the troops of pesticides purchased privately is not known, although there have been reports of some individuals’ (improper and unsafe) use of pet flea collars during Gulf War service. It *is* known that troops deployed to other theaters of operation after the Gulf War used privately obtained non-authorized pesticide products. Patterns of use and safety, as well as actual types of pesticides used, are not known for either Gulf War or post Gulf War deployments.
Finally, it is not known what types of pest control practices were in use in the Gulf. Field Sanitation Teams may have had standard procedures to follow, but it is not known if these procedures were actually used. For units without FSTs, it is quite possible that a standard civilian misjudgment was common: If some pesticide is good, more is better. When this rule is applied to pesticide use, disaster can ensue.
Pesticide use in the Gulf has not greatly concerned some government groups looking into the illnesses experienced by Gulf War veterans.
Lack of information about the use of pesticides in the Gulf has not been an impediment to government groups offering opinions about Gulf War illnesses and their causes: For the most part, such groups have either not focused on pesticides in detail as a potential risk factor for the troops, or they have acknowledged that pesticides pose some risk--but in the next breath conclude that pesticides are unlikely to be implicated as causative agents in Gulf War health problems.
For instance, the Final Report of the Presidential Advisory Committee on Gulf War Veterans Illnesses (January 1997) stated: "While DOD can document what pesticides were shipped--and how much-- there are virtually no records available today on how these pesticides were used in the gulf region. DOD made no provisions for collecting or keeping distribution or use records of US-shipped and approved products."
Although the Report makes much of the fact that pesticides approved for use in the Gulf were "EPA and FDA approved," it does not mention that each year, thousands of "pesticide incidents" involving EPA- and FDA- approved pesticides are reported to Poison Control Centers in the US. Nor does the Report indicate the frequency with which pesticides are mishandled , or casually handled, by civilians. Nor does it indicate that pesticide-related health effects are thought to be frequently overlooked by physicians in the US. Nor does it indicate that pesticide-related health effects may be cumulative, or that delayed effects of pesticide exposure may differ substantially from acute effects, or that delayed effects may occur without acute poisoning in some cases.
In June 1997 the General Accounting Office reported to Congress their disagreement with the Presidential Advisory Committee’s statements on pesticides and Gulf War related illness. GAO based its disagreement on a literature review that turned up evidence of the possibility of delayed neuropathy in the absence of acute pesticide poisoning, as well as research showing the synergistic effects of DEET, permethrin and pyridostigmine bromide in combination.
GAO’s criticisms seem to lie on the tip of an iceberg of questions about pesticides used in the Gulf. In view of what is known about pesticides approved for use in the Gulf, and their known health effects-- as well as what is *not* known about actual pesticide use practices in the Gulf (both authorized and unauthorized)-- it is at least premature to conclude that pesticides were “unlikely” to have contributed to the illnesses experienced by the veterans.
It may be important to find out more about how pesticides were used in the Gulf, who used them, and how. It is not clear that current research on Gulf War illnesses involves seeking the kinds of information identified here as necessary for a full understanding of pesticide exposures encountered by the troops in the Gulf: GAO identified 12 ongoing studies involving pesticides used in the Gulf, but since only *one* team reported that they were seeking exposure information other than self-reports from veterans, the chances seem slim that more substantive information will be forthcoming. And as time passes, it will become increasingly difficult to obtain the information needed.
Louise Kosta, Chief writer, The Human Ecologist.
Opinions expressed are those of the author *only*
and do not reflect the position of HEAL, its Governing Board, its staff, contractors or others.
Perspective: Environment and health
Quotable (1) American attitudes toward pesticides c. 1990
“[Two EPA surveys of non-occupational pesticide use in the US published in the early 1990’s indicated that] people choose to use and store pesticides indoors in their homes (approximately 85%). They don’t take many precautions when they apply them themselves (no precautions with approximately 60% of sprayed products). Nor do they recall learning of precautions to take from the labels of self-applied pesticides or from materials given them by pesticide applicators (75%). They don’t know what pesticides have been applied to their residences by previous residents, and they don’t keep track of what they have used themselves.” From “Pesticides in the home,” The Human Ecologist #60, Winter 1993.
"Problems with human health and problems within the environment are , in most cases, so intertwined as to be inseparable. Problems within the environment may not become apparent until many years after their initiation or until human health is affected. Resolving these problems requires an understanding of the relationships between individual components of the environment. In other words, it is necessary to encompass all areas of environmental health, so that human health issues may be recognized before major health problems become established. Only when all areas of environmental health are considered can the interdependence of the environment and human life be recognized." --Gary E.R.Hook and George Lucier, Editors-in-chief, _Environmental Health Perspectives_ . In _Twenty Years of Environmental Health Research_ ( Washington DC: DHHS-PHS-NIH-NIEHS 1993).