The active site of human paraoxonase (PON1)

Ideally we would like to treat people exposed to nerve agents with an enzyme that rapidly destroys nerve agents. The enzymes considered for such a role include human butyrylcholinesterase (BChE), acetylcholinesterase (AChE), carboxylesterase and paraoxonase (PON1). Success has been achieved in endowing BChE with the ability to hydrolyze organophosphates. The G117H mutant of BCHE hydrolyzes sarin and VX, whereas the double mutant G117H/E197Q hydrolyzes soman (Millard et al. Biochemistry 1995; 34: 15925-15933; 1998; 37: 237-247). However, the rates of organophosphate hydrolysis are slow and a faster organophosphate hydrolase is being sought. Native PON1 hydrolyzes paraoxon with a catalytic efficiency, of 2.4 x 10(6) M(-1) x min(-1), and our goal is to improve the organophosphate hydrolase activity of PON1. To achieve this we need to identify the amino acids in the active site of PON1. Using site-directed mutagenesis and expression in human 293T cells, we have identified the following eight amino acids as being essential to PON1 activity: W280, H114, H133, H154, H242, H284, E52 and D53. Fluorescence of PON1 complexed to terbium ion shows that at least one tryptophan is close to the calcium binding site.

Army medical laboratory telemedicine: role of mass spectrometry in telediagnosis for chemical and biological defense

An army medical field laboratory presently has the capability of performing standard protocols developed at the US Army Medical Research Institute of Chemical Defense for verification of nerve agent or sulfur mustard exposure. The protocols analyze hydrolysis products of chemical warfare agents using gas chromatography/mass spectrometry. Additionally, chemical warfare agents can produce alkylated or phosphorylated proteins following human exposure that have long biological half-lives and can be used as diagnostic biomarkers of chemical agent exposure. An analytical technique known as matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS) currently is being examined for its potential to analyze these biomarkers. The technique is capable of detecting large biomolecules and modifications made to them. Its fast analysis time makes MALDI-TOF/MS technology suitable for screening casualties from chemical or biological attacks. Basic operation requires minimal training and the instrument has the potential to become field-portable. The limitation of the technique is that the generated data may require considerable expertise from knowledgeable personnel for consultation to ensure correct interpretation. The interaction between research scientists and field personnel in the acquisition of data and its interpretation via advanced digital telecommunication technologies can enhance rapid diagnosis and subsequently improve patient care in remote areas.

Development of an immunoassay for diagnosis of exposure to toxic organophosphorus compounds

Currently, diagnosis of exposure to toxic low-molecular-weight compounds is effected by the use of chromatographic techniques. Such an approach is limited by the need for expensive equipment and sample clean-up before carrying out the analysis. To overcome those drawbacks, we have been involved in the development of an immunoassay for diagnosis of exposure to toxic organophosphorus compounds such as pinacolylmethyl phosphonofluoridate (soman), which is a chemical warfare agent. Prior estimates suggested that it is necessary to be able to detect soman at a concentration below 2.5 x 10(-7) M. Using four previously developed monoclonal antibodies, an enzyme-linked immunosorbant assay (ELISA) was used to optimize assay conditions and identify the antibody with the highest apparent affinity. The minimum required assay time was 2.0-2.5 h with no loss in sensitivity. To determine the specificity of the highest affinity antibody, a competitive inhibition enzyme immunoassay (CIEIA) was performed with six structural analogs of soman. The IC50 values for these analogues were 5 x 10(-7) M for 4-nitrophenylpinacolylmethylphosphonate, 8 x 10(-7) M for dipinacolylmethylphosphonate, 2 x 10(-6) M for diisopropylmethylphosphonate, 3 x 10(-5) M for 4-nitrophenylmethyl(phenylphosphinate) and 6.5 x 10(-5) M for 4-nitrophenylethyl(phenyl)phosphinate. 4-Nitrophenyl-di(n-butyl)phosphinate did not inhibit binding. Those inhibitors with branched alkyl side-chains, similar to the soman molecule, were effective inhibitors. Compounds, which contained predominately aromatic groups, were poor inhibitors. We are continuing to probe the binding specificity of the monoclonal antibody to determine its utility in further assay development. Our present results suggest that the antibody chosen may have the appropriate specificity and affinity for immunodiagnosis of exposure to soman.

Progress on the road to new nerve agent treatments

In the 50 years since nerve agents were developed a great deal has been learned about their acute toxicity, treatment and prophylactic strategies. However, the currently fielded treatments are not significantly different from those available at the end of World War II. Reasons for this lack of progress and strategies to circumvent those intrinsic problems that have impeded progress are discussed, with emphasis on the development of scavengers to be introduced as prophylactics that will significantly reduce the effective dose and thus protect against multiple times the normal LD50.

Combination anticonvulsant treatment of soman-induced seizures

These studies investigated the effectiveness of combination treatment with a benzodiazepine and an anticholinergic drug against soman-induced seizures. The anticholinergic drugs considered were biperiden, scopolamine, trihexaphenidyl, and procyclidine; the benzodiazepines were diazepam and midazolam. Male guinea pigs were implanted surgically with cortical screw electrodes. Electrocorticograms were displayed continually and recorded on a computerized electroencephalographic system. Pyridostigmine (0.026 mg x kg(-1), i.m.) was injected as a pretreatment to inhibit red blood cell acetylcholinesterase by 30-40%. Thirty minutes after pyridostigmine, 2 x LD50 (56 microg x kg(-1)) of soman was injected s.c., followed 1 min later by i.m. treatment with atropine (2 mg x kg(-1)) + 2-PAM (25 mg x kg(-1)). Electrographic seizures occurred in all animals. Anticonvulsant treatment combinations were administered i.m. at 5 or 40 min after seizure onset. Treatment consisted of diazepam or midazolam plus one of the above-mentioned anticholinergic drugs. All doses of the treatment compounds exhibited little or no antiseizure efficacy when given individually. The combination of a benzodiazepine and an anticholinergic drug was effective in terminating soman-induced seizure, whether given 5 or 40 min after seizure onset. The results suggest a strong synergistic effect of combining benzodiazepines with centrally active anticholinergic drugs and support the concept of using an adjunct to supplement diazepam for the treatment of nerve-agent-induced seizures.

Psycho-physiological effects of the terrorist sarin attack on the Tokyo subway system

The investigation describes the follow-up of the victims of the 1995 Tokyo sarin attack who were followed by a team at the St. Luke's International Hospital. A symptom questionnaire ("St. Luke's Questionnaire") was developed and given 2, 3, and 5 years following the sarin attack. Somatic and psychological symptoms have continued for 5 years after the incident. New post-traumatic stress disorder diagnostic criteria, which include physical symptoms, were developed and applied for assessment of the outcomes. The St. Luke's cohort was also compared with other Japanese sarin attack cohorts. Interventions, including counseling, medical treatments, and support group activities, were associated with fewer symptoms among the victims.

Effects of sarin on the nervous system in rescue team staff members and police officers 3 years after the Tokyo subway sarin attack

Although the clinical manifestations of acute sarin poisoning have been reported in detail, no comprehensive study of the chronic physical and psychiatric effects of acute sarin poisoning has been carried out. To clarify the chronic effects of sarin on the nervous system, a cross-sectional epidemiologic study was conducted 3 years after the Tokyo subway sarin attack. Subjects consisted of the rescue team staff members and police officers who had worked at the disaster site. Subjects consisted of 56 male exposed subjects and 52 referent subjects matched for age and occupation. A neurobehavioral test, stabilometry, and measurement of vibration perception thresholds were performed, as well as psychometric tests to assess traumatic stress symptoms. The exposed group performed less well in the backward digit span test than the referent group in a dose-effect manner. This result was the same after controlling for possible confounding factors and was independent of traumatic stress symptoms. In other tests of memory function, except for the Benton visual retention test (mean correct answers), effects related to exposure were also suggested, although they were not statistically significant. In contrast, the dose-effect relationships observed in the neurobehavioral tests (psychomotor function) were unclear. None of the stabilometry and vibration perception threshold parameters had any relation to exposure. Our findings suggest the chronic decline of memory function 2 years and 10 months to 3 years and 9 months after exposure to sarin in the Tokyo subway attack, and further study is needed.

Conjunctival dysplasia in soldiers exposed to mustard gas during the Iraq-Iran war: scrape cytology

OBJECTIVE

To describe the conjunctival scrape cytology findings in Iraq-Iran war veterans exposed to mustard gas and to detect malignant transformation at an early stage.

STUDY DESIGN

Twenty-two male war veterans (29-54 years old) who were exposed to chemical bombing about 14 years earlier, formed the base of this study. All of them had chronic eye problems, such as dryness, conjunctival scarring and decreased visual acuity. Conjunctival scrape cytology was performed for cytologic study.

RESULTS

Among 22 cases of conjunctival scarring, 9 were diagnosed as dysplasia. Mild inflammation and squamous metaplasia were also noted. Squamous cell carcinoma was not identified.

CONCLUSION

Conjunctival scraping cytology is useful for the diagnosis of dysplasia in soldiers exposed to mustard gas during of the Iraq-Iran war. This method is also effective for follow-up study.

Impact of chemical warfare with agent orange on women's reproductive lives in Vietnam: a pilot study

During the American war in Vietnam, huge quantities of the highly toxic herbicide dioxin ('Agent Orange'), were sprayed over large areas of central and south Vietnam. In addition to polluting the environment and causing cancers and other diseases in those directly exposed to it, dioxin has caused high rates of pregnancy loss, congenital birth defects and other health problems in their children. This paper reports the findings of a pilot study in the year 2000 among 30 Vietnamese women whose husbands and/or who themselves were exposed to Agent Orange. The aim was to develop research in order to explore the impact of chemical warfare on people's lives. Using the reproductive lifeline and semi-structured interviews, information was gathered on both partners' periods of exposure to Agent Orange, pregnancy outcomes, perceived health problems of children and experiences of living with handicapped children. The women had had a high number of miscarriages and premature births. About two-thirds of their children had congenital malformations or developed disabilities within the first years of life. Most of the families were poor, aggravated by impaired health in the men, the burden of caring for disabled children, and feelings of guilt and inferiority. The plight of 'Agent Orange families' is special and should be placed in its historical and political context.

[Sanitary and epidemiological services in chemical weapons elimination]

Chemical weapons elimination on Russian Federation territory positions some problems that should be solved to prevent harm for public health and environment in Russia. The author specified corresponding methodic recommendations.

Exposure to armament wastes and leukemia: a case-control study within a cluster of AML and CML in Germany

An unusually high incidence of acute myeloid leukemia (AML) and chronic myeloid leukemia (CML) concentrated in a specific locality of a region in Germany motivated a descriptive incidence study in that region which showed a near 10-fold increased risk of CML among males but not among females (Kolb G, Becker N, Scheller S, Zugmaier G, Pralle H, Wahrendorf J, Havemann K. Increased risk of acute myelogenous leukemia (AML) and chronic myelogenous leukemia (CML) in a County of Hesse, Germany, Soc Prev Med 1993;38:190-195). Since a serious environmental contamination of areas in this locality with armament wastes containing toluene-derivatives has been known for a long time, the hypothesis arose that TNT production and the related severe contamination of soil and water might be responsible for the observed higher risk. We carried out a case-control study within the cluster to test this hypothesis. Overall, the results do not confirm the hypothesis. There is an indication of a relationship of an increased odds ratio with the exposure for a small group of persons who lived at a particular site in one of the two communities involved during the peak phase of TNT production during the 1940s. However, this finding is spurious and cannot explain the large majority of cases which occurred in that area in the 1980s. At the moment, no other explanation can be given for the increased risk of leukemias in that area.

Symptoms of Gulf War veterans possibly exposed to organophosphate chemical warfare agents at Khamisiyah, Iraq

During the 1991 Gulf War, some Allied troops were potentially exposed to sarin/cyclosarin as the result of the destruction of Iraqi munitions at Khamisiyah. To evaluate the prevalence of past and current symptoms known to be associated with exposure to these chemical warfare agents, the authors conducted a computer-assisted telephone survey of 2,918 U.S. Gulf War veterans. Veterans who had participated in or witnessed the demolition in 1991 were more likely to report historical or extant symptoms than were veterans from other military units. These results should be viewed cautiously because they are based on symptoms recalled nine years after the event without precise characterization of exposure. Nonetheless, the findings suggest that symptoms consistent with low-level sarin exposure may have initially occurred, and health effects may have persisted in the veterans who were nearest to the demolition activity. Further research is warranted.

Disruption of gas exchange in mice after exposure to the chemical threat agent phosgene

The use of chemical warfare agents, such as the pulmonary irritant gas phosgene, is a real and constant threat not only from belligerent nations but from terrorist groups as well. Phosgene is both easy and inexpensive to produce and as such is a potential candidate for use as a threat agent. Phosgene attacks the deep lung after inhalation and can severely compromise pulmonary mechanics and gas exchange, rendering the exposed individual incapacitated. If exposure is severe, death can ensure by asphyxiation secondary to pulmonary edema formation. This paper examines the effects on lung tissue in mice over 24 hours after exposure to the irritant gas phosgene. Exposure to phosgene produced respiratory acidosis by decreasing pH, partial pressure of oxygen, O2 saturation, and increasing partial pressure of carbon dioxide. Exposure to phosgene also induced temporal increases in lung tissue gravimetric parameters such as lung tissue wet weight/dry weight ratio, which is a positive indicator of pulmonary edema formation, and dry lung weight, an indicator of lung cellular hyperaggregation. Blood gases and pH tend to normalize within 24 hours, whereas gravimetric parameters remain increased. Temporal changes in these physiological indicators of lung injury may help to explain why past exposures to phosgene required lengthy hospitalization.

Toxins as weapons of mass destruction. A comparison and contrast with biological-warfare and chemical-warfare agents

Toxins are toxic chemical compounds synthesized in nature by living organisms. Classifiable by molecular weight, source, preferred targets in the body, and mechanism of action, they include the most potent poisons on the planet, although considerations of production, weaponization, delivery, environmental stability, and host factors place practical limits on their use as WMD. The two most important toxin threats on the battlefield or in bioterrorism are probably botulinum toxin (a series of seven serotypes, of which botulinum toxin A is the most toxic for humans) and SEB, an incapacitating toxin. Ricin and the trichothecene mycotoxins, including T-2 mycotoxin, are of lesser concern but are still potential threats. Botulinum toxin is a neurotoxin, ricin and trichothecene mycotoxins are membrane-damaging proteins, and SEB is a superantigen capable of massive nonspecific activation of the immune system. The clinical intoxications resulting from exposure to and absorption (usually by inhalation) of these agents reflect their underlying pathophysiology. Because of the hybrid nature of toxins, they have sometimes been considered CW agents and sometimes BW agents. The current trend seems to be to emphasize their similarities to living organisms and their differences from CW agents, but examination of all three groups relative to a number of factors reveals both similarities and differences between toxins and each of the other two categories of non-nuclear unconventional WMD. The perspective that groups toxins with BW agents is logical and very useful for research and development and for administrative and treaty applications, but for medical education and casualty assessment, there are real advantages in clinician use of assessment techniques that emphasize the physicochemical behavior of these nonliving, nonreplicating, intransmissible chemical poisons.

Exposure to liquid sulfur mustard

Chemical weapons continue to pose a serious threat to humanity. With the use of chemical weapons by terrorists in Tokyo, and the projected disarming of the chemical weapon stockpile in this country, the possibility that emergency physicians will encounter patients contaminated by chemical munitions, such as sulfur mustard, exists. Mustard is a vesicating agent with a long latency between exposure and symptoms. Exposure can cause burns, conjunctivitis, pneumonia, and death. We describe 3 workers exposed to mustard at a chemical weapon storage facility. This article reports the first case of an exposure to mustard at a storage facility, as well as the first documented incident occurring in the United States. All physicians who manage patients in an acute care setting should be aware of the presentation and emergency treatments involving patients contaminated with mustard.

An 'injury-time integral' model for extrapolating from acute to chronic effects of phosgene

The present study compares acute and subchronic episodic exposures to phosgene to test the applicability of the 'concentrationxtime' (CxT) product as a measure of exposure dose, and to relate acute toxicity and adaptive responses to chronic toxicity. Rats (male Fischer 344) were exposed (six hours/day) to air or 0.1, 0.2, 0.5 and 1.0 ppm of phosgene one time or on a repeated regimen for up to 12 weeks as follows: 0.1 ppm (five days/week), 0.2 ppm (five days/week), 0.5 ppm (two days/week), or 1.0 ppm (one day/week) (note that the CxT for the three highest exposures was the same). Animals were sacrificed at 4, 8, and 12 weeks during the exposure and after four weeks recovery. Bronchoalveolar lavage (BAL) was performed 18 hours after the last exposure for each time period and the BAL supernatant assayed for protein. Elevated BAL fluid protein was defined as 'acute injury', diminished response after repeated exposure was defined as 'adaptation', and increased lung hydroxyproline or trichrome staining for collagen was defined as 'chronic injury'. Results indicated that exposures that cause maximal chronic injury involve high exposure concentrations and longer times between exposures, not high CxT products. A conceptual model is presented that explains the lack of CxT correlation by the fact that adaptation reduces an 'injury-time integral' as phosgene exposure is lengthened from acute to subchronic. At high exposure concentrations, the adaptive response appears to be overwhelmed, causing a continued injury-time integral, which appears to be related to appearance of chronic injury. The adaptive response is predicted to disappear if the time between exposures is lengthened, leading to a continued high injury-time integral and chronic injury. It has generally been assumed that long, continuous exposures of rodents is a conservative approach for detecting possible chronic effects. The present study suggests that such an approach my not be conservative, but might actually mask effects that could occur under intermittent exposure conditions.

Response of F344 rats to inhalation of subclinical levels of sarin: exploring potential causes of Gulf War illness

Subclinical, repeated exposures of F344 rats to sarin resulted in brain alterations in densities of chlonergic receptor subtypes that may be associated with memory loss and cognitive dysfunction. The exposures also depressed the immune system. The rat appears to be a good model for studying the effects of subclinical exposure to a nerve gas.

Ocular injuries caused by mustard gas: diagnosis, treatment, and medical defense

Sulfur mustard has been used as a vesicant chemical warfare agent. To investigate the ocular damage it causes, we studied the effects on chemical casualties in the Iran-Iraq War. The patient population consisted of more than 5,000 chemical casualties, both military and civilian. The range of ocular damage was wide. The most common ocular effects were conjunctivitis and photophobia. Patients with significant corneal involvement are at risk for corneal ulceration and rarely for anterior chamber scarring and neovascularization, any of which would result in prolonged disability. In conclusion, the eye is the organ most sensitive to sulfur mustard vapor. Ocular injuries generally heal completely. In severe cases, blindness may occur. The need for corneal transplantation is rare.

Anaesthesia and critical care considerations in nerve agent warfare trauma casualties

Nerve agents (NA) (tabun, sarin, suman, VX) have been stocked around the world for some time and still present a major threat to civilian as well as to military populations. Since NA can be delivered through both an aerial spray system and a ballistic system, victims could suffer both NA intoxication and multiple trauma necessitating urgent surgical intervention followed by intensive care. These patients can be expected to be extremely precarious neurologically, respiratorily and haemodynamically. Moreover, their clinical signs can be misleading. Further exacerbating the problem is the fact that interactions of NA with the pharmacological agents used for resuscitation and/or during anaesthesia can aggravate organ instability even more and possibly cause systemic collapse. There are no protocols for perioperative critical care and early assessment or for the administration of anaesthesia for surgical interventions in such combined multiple trauma and intoxicated casualties. We propose a scheme for the administration of critical care and anaesthesia based on the scant anecdotal reports that have emerged after the occurrence of local accidents involving NA intoxication and on the neuropharmacological knowledge of the pesticide organophosphate poisoning database, these compounds being related chemical substances.

The effects of sarin-like and soman-like organophosphorus agents on MAPK and JNK in rat brains

One sarin-like and one soman-like organophosphorus agent [bis(isopropyl methyl)phosphonate, BIMP and bis(pinacolyl methyl)phosphonate, BPMP] were injected intravenously (iv) in rats. An increase in the tyrosine phosphorylation of several proteins in the cytosol fraction of the brain was observed. Activation of c-Jun N-terminal kinase (JNK) and slight activation of mitogen-activated protein kinase (MAPK) in the cytosol were also observed. The activation of these enzymes may be related to the high toxicity of these nerve agents.

The role of the sand in chemical warfare agent exposure among Persian Gulf War veterans: Al Eskan disease and "dirty dust"

The purpose of this paper is to inquire into the relationship between Al Eskan disease and the probable exposure to chemical warfare agents by Persian Gulf War veterans. Al Eskan disease, first reported in 1991, compromises the body's immunological defense and is a result of the pathogenic properties of the extremely fine, dusty sand located in the central and eastern region of the Arabian peninsula. The disease manifests with localized expression of multisystem disorder. Signs and symptoms of Al Eskan disease have been termed by the news media "Persian Gulf syndrome." The dust becomes a warfare agent when toxic chemicals are microimpregnated into inert particles. The "dirty dust" concept, that the toxicity of an agent could be enhanced by absorption into inactive particles, dates from World War I. A growing body of evidence shows that coalition forces have encountered Iraqi chemical warfare in the theater of operation/Persian Gulf War to a much greater extent than early U.S. Department of Defense information had indicated. Veterans of that war were exposed to chemical warfare agents in the form of direct (deliberate) attacks by chemical weapons, such as missiles and mines, and indirect (accidental) contamination from demolished munition production plants and storage areas, or otherwise. We conclude that the microimpregnated sand particles in the theater of operation/Persian Gulf War depleted the immune system and simultaneously acted as vehicles for low-intensity exposure to chemical warfare agents and had a modifying-intensifying effect on the toxicity of exposed individuals. We recommend recognition of a new term, "dirty sand," as a subcategory of dirty dust/dusty chemical warfare agents. Our ongoing research efforts to investigate the health impact of chemical warfare agent exposure among Persian Gulf War veterans suggest that Al Eskan disease is a plausible and preeminent explanation for the preponderance of Persian Gulf War illnesses.

Review of the U.S. Army's health risk assessments for oral exposure to six chemical-warfare agents. Introduction

The U.S. Army is under a congressional mandate and the Chemical Weapons Convention of January 1993 to destroy its entire stockpile of chemical munitions. In addition to stockpiled munitions, nonstockpile chemical materiel (NSCM) has been identified for destruction. NSCM includes a host of lethal wastes from past disposal efforts, unserviceable munitions, chemically contaminated containers, chemical-production facilities, newly located chemical munitions, known sites containing substantial quantities of buried chemical weapons and wastes, and binary weapons and components. There are eight stockpile sites located in the continental United States and one on an island in the Pacific Ocean, and 82 NSCM locations have been identified. There are concerns, based on storage and past disposal practices, about soil and groundwater contamination at those sites. Six of the most commonly found chemical-warfare agents at stockpile and NSCM sites are the nerve agents GA, GB, GD, and VX and the vesicating (blistering) agents sulfur mustard and lewisite. To ensure that chemical contamination is reduced to safe concentrations at stockpile and NSCM sites before they are used for residential, occupational, or wildlife purposes, the U.S. Army requested that health-based exposure limits for GA, GB, GD, VX, sulfur mustard, and lewisite be developed to protect the public and the environment. Oak Ridge National Laboratory (ORNL) was asked to conduct the health risk assessments and propose chronic oral reference doses (RfDs) and, where appropriate, oral slope factors (SFs) for the six agents. RfDs are toxicological values developed for noncancer effects and used as reference points to limit human oral exposure to potentially hazardous concentrations of chemicals thought to have thresholds for their effects. RfDs are estimates (with uncertainty spanning an order of magnitude or greater) of daily oral chemical exposures that are unlikely to have deleterious effects during a human lifetime. For chemicals identified as carcinogens (e.g., sulfur mustard), SFs are also calculated. SFs are estimates of upper-bound lifetime cancer risk from chronic exposure to an agent. The Army's Surgeon General adopted the proposed RfDs and SFs developed by ORNL as interim values to ensure that consistent health-based criteria were applied in ongoing initiatives requiring decisions on the safety of contaminated sites. The Army's Surgeon General also requested that the National Research Council (NRC) independently review the scientific validity of these values. The NRC assigned this task to the Committee on Toxicology (COT), and a multidisciplinary subcommittee of experts was convened to assess the scientific validity of the interim RfDs developed for GA, GB, GD, VX, sulfur mustard, and lewisite and the SF developed for sulfur mustard. Specifically, the subcommittee was asked to (1) determine whether all the relevant toxicity data were considered appropriately; (2) review the uncertainty, variability, and quality of the data; (3) determine the appropriateness of the assumptions used to derive the RfDs (e.g., the application of uncertainty factors); and (4) identify data gaps and make recommendations for future research. Although multiple agents are present at stockpile and NSCM sites, the subcommittee was asked to evaluate the agents only on an individual basis. Furthermore, although the most likely routes of exposure to chemical-warfare agents at these sites are the inhalation and dermal routes, the subcommittee was only asked to evaluate toxicological risk from the oral route at this time. The Army is in the process of developing inhalation exposure guidelines. The subcommittee was also not asked to address issues related to risk management, such as technology, detection, and feasibility.

You can transform your HazMat policy

In addition to a protocol for everyday hazardous materials incidents, you need one for weapons of mass destruction, which include nuclear, chemical, or biologic agents. Direct minimally injured patients to a holding area. Have a plan for decontaminating hundreds or perhaps thousands of people. Have reference tables that list agents, symptoms, and the antidotes and decontamination supplies or various exposures.

Sequelae of sarin toxicity at one and three years after exposure in Matsumoto, Japan

In order to clarify the later sequelae of sarin poisoning that occurred in Matsumoto City, Japan, on June 27, 1994, a cohort study was conducted on all persons (2052 Japanese people) inhabiting an area 1050 meters from north to south and 850 meters from east to west with the sarin release site in the center. Respondents numbered 1237 and 836 people when surveys were conducted at one and three years after the sarin incident, respectively. Numbers of persons with symptoms of sarin toxicity were compared between sarin victims and non-victims. Of the respondents, 58 and 46 people had symptoms associated with sarin such as fatigue, asthenia, shoulder stiffness, asthenopia and blurred vision at both points of the survey, respectively. The prevalences were low; some complained of insomnia, had bad dreams, difficulty in smoking, husky voice, slight fever and palpitation. The victims who had symptoms one year after the incident had a lower erythrocyte cholinesterase activity than did those who did not have symptoms at the early stage; such persons lived in an area with a 500 meter long axis north east from the sarin release site. The three-year cohort study clearly showed that the odds ratios of almost all of the symptoms were high in the sarin-exposed group, suggesting a positive relationship between symptoms and grades of exposure to sarin. These results suggest that symptoms reported by many victims of the sarin incident are thought to be sequelae related to sarin exposure.

Strategies to assess validity of self-reported exposures during the Persian Gulf War. Portland Environmental Hazards Research Center

Research in the area of Persian Gulf War Unexplained Illnesses (PGWUI) is heavily dependent on self-reports of exposures. The Portland Environmental Hazards Research Center (PEHRC) conducted a population-based case-control study utilizing techniques to measure the magnitude of potential error in self-reports of exposure. While it is impossible to verify most exposures in the Persian Gulf War (PGW), results of our study reveal significant overreporting of exposures that can be verified based on the time period served in the Persian Gulf. Test-retest reliability estimates indicate inconsistency in frequency and rate of self-reported exposures during the PGW. Unexplained illness in PGW veterans has received much political and scientific attention. Self-reported exposures in surveys returned preceding and following media reports on particular exposure such as nerve gas or pesticides are presented. These results are useful in the interpretation of findings related to the PGWUI and in the design of future investigations.

Characteristics of bronchoalveolar lavage fluid in patients with sulfur mustard gas-induced asthma or chronic bronchitis

PURPOSE

To examine the pattern of immunoglobulins and cellular constituents in bronchoalveolar lavage fluid obtained from patients with sulfur mustard gas-induced asthma or chronic bronchitis as compared with healthy control subjects.

SUBJECTS AND METHODS

We studied two groups of nonsmoking veterans with either bronchial asthma (n = 21) or chronic bronchitis (n = 28) believed to have been caused by sulfur mustard gas exposure and a third group of healthy, nonsmoking, non-sulfur mustard gas exposed controls (n = 17). Bronchoalveolar lavage was performed in all three groups. The cellular constituents, albumin content, and immunoglobulin concentrations were determined.

RESULTS

The three groups did not differ in age or in the serum albumin and immunoglobulin concentrations. The volume of bronchoalveolar lavage fluid recovered was approximately 10% less in the patients with asthma and chronic bronchitis (P = 0.008). The proportions of lymphocytes among the bronchoalveolar lavage cells were similar in all three groups, whereas the proportion of eosinophils was greater in lavage fluid from the asthmatic subjects than in either the healthy control subjects or the patients with chronic bronchitis (P = 0.0001). Both the total number of the recovered cells per milliliter of lavage fluid and the proportion of neutrophils were significantly greater in bronchoalveolar lavage from patients with chronic bronchitis than in healthy subjects or in the patients with asthma (all P <0.001).

CONCLUSION

The bronchoalveolar lavage cellular constituents of patients with sulfur mustard gas-induced asthma and chronic bronchitis are similar to those that have been observed previously in patients with asthma and chronic bronchitis from other common causes.

The prevention and treatment of cutaneous injury secondary to chemical warfare agents. Application of these finding to other dermatologic conditions and wound healing

Chemical warfare agents are easily and inexpensively produced and are therefore potentially accessible to even underdeveloped nations and are a threat to civilian populations as well as advancing troops. Sulfur mustard is by far the most significant chemical warfare agent that produces cutaneous injury. Significant advances over the past few years have been made in understanding the pathophysiology of the lesions produced by sulfur mustard, as well as development of barrier creams and pre and post exposure therapies to moderate the damage and accelerate healing. Not only have these advances improved our understanding of the sulfur mustard injury and the care of the patients, these are potentially numerous applications for these findings in other dermatologic conditions including the treatment of chronic wounds.

The use of laser Doppler imaging as an aid in clinical management decision making in the treatment of vesicant burns

Vesicants are a group of chemicals recognised, under the terms of the Chemical Weapons Convention, as potential chemical warfare agents whose prime effect on the skin is to cause burns and blistering. Experience of the clinical management of these injuries is not readily available and therefore an accurate assessment of the severity of the lesion and extent of tissue involvement is an important factor when determining the subsequent clinical management strategy for such lesions. This study was performed to assess the use of laser Doppler imaging (LDI) as a noninvasive means of assessing wound microvascular perfusion following challenge with the vesicant agents (sulphur mustard or lewisite) by comparing the images obtained with histopathological analysis of the lesion. Large white pigs were challenged with sulphur mustard (1.91 mg cm(-2)) or lewisite (0.3 mg.cm(-2)) vapour for periods of up to 6 h At intervals of between 1 h and 7 days following vesicant challenge, LDI images were acquired and samples for routine histopathology were taken. The results from this study suggest that LDI was: (i) a simple, reproducible and noninvasive means of assessing changes in tissue perfusion, and hence tissue viability, in developing and healing vesicant burns; (ii) the LDI images correlates well with histopathological assessment of the resulting lesions and the technique was sufficiently sensitive enough to discriminate between skin lesions of different aetiology. These attributes suggest that LDI would be a useful investigative tool that could aid clinical management decision making in the early treatment of vesicant agent-induced skin burns.

Use of surrogate markers for drugs of military importance

In the future, U.S. military forces will be faced with opposing forces that have chemical and biological weapon capabilities. Although drugs used against these agents would be an ideal solution to protecting soldiers, the ability to test their efficacy in humans is limited by several ethical and technical problems: (1) the high risk of toxicity to volunteers; (2) the risk of delayed side effects in the volunteers; and (3) the inability to extrapolate effects against sublethal doses to efficacy against lethal doses. The Food and Drug Administration (FDA) relies on safety and efficacy data in humans, making approval for these types of drugs difficult. An alternative approach for regulatory approval would be to use surrogate markers. Surrogate markers are biochemical or physiologic measurements that demonstrate the direct effect of the drug. Surrogate markers, such as CD4 counts and viral RNA levels, have been used recently in the anti-human immunodeficiency virus drug approval process with success. A drug development program using surrogate markers must meet several criteria, including demonstrated efficacy in animal models, correlation between efficacy and the surrogate marker, a link between the surrogate marker and the pathophysiology and toxicologic effects of the agent, and the ability to produce the surrogate marker in humans. This article illustrates the use of drug-induced methemoglobin as a surrogate marker for protection against cyanide intoxication. Safety issues regarding this class of drugs would also have to be pursued aggressively during and after their use by military forces. Demonstrating that the drug satisfies these criteria would be a platform for approval by the FDA. The guidelines mentioned above should be an acceptable approach for FDA approval, scientific researchers, medical practitioners, and the soldiers using these drugs.

Self-reported chemical sensitivity and wartime chemical exposures in Gulf War veterans with and without decreased global health ratings

This cross-sectional telephone survey study assessed prevalence rates of current chemical sensitivity, frequency of chemical odor intolerance, and self-reported Persian Gulf chemical exposures among 41 randomly sampled Department of Veterans Affairs outpatients who were Persian Gulf War (PGW) and PGW-era veterans. The participants were drawn from an initial random list of 100 veterans, of whom 28 PGW and 20 era veterans had correct telephone data on file. Of those contacted, 86% of PGW veterans (24/28) and 85% of era veterans (17/20) agreed to participate. Significantly more PGW veterans with poorer global health after military service reported considering themselves now "especially sensitive to certain chemicals" (86%, 12/14) than did the PGW veterans or era veterans in stable health (both comparison groups 30%, 3/10). Among PGW veterans, the subset with worse health associated with marked increases in chemical odor intolerance since their military service had a significantly higher odds ratio for exposure to multiple chemicals, notably wartime pesticides and insect repellent, than did comparison groups. The high rate of chemical sensitivity of PGW veterans with deteriorated health is almost three times that in PGW-era veterans and in elderly primary care outpatient veterans at the same Department of Veterans Affairs medical center and in community-based civilian samples (i.e., 30%). These preliminary findings suggest the need for further study of chemical sensitivity, including tests for acquired increases in neural sensitizability to multiple low-level chemicals, in ill PGW veterans.

Chronic neuropathic symptoms after exposure to mustard gas: a long-term investigation

BACKGROUND

Long-term investigations of persons exposed to mustard gas are few and have primarily focused on its carcinogenic properties. To our knowledge neuropathic pain has never been described.

OBJECTIVE

We investigated late symptoms in the skin after exposure to sulfur mustard.

METHODS

Five patients exposed to mustard gas during battlefield operations in the Middle East and five fishermen accidentally exposed to sulfur mustard by pulling shells leaking the chemical agent aboard their fishing vessels participated in this study. Clinical examination of the patients from the Middle East and telephone interviews with the fishermen were performed.

RESULTS

All patients suffered from neuropathic pain or other deafferentation symptoms.

CONCLUSION

Persistent damage to the afferent nerve system resulting in chronic neuropathic symptoms is probably a frequent complication in persons exposed to mustard gas.

Emergency department management of nerve agent exposure

Nerve agents are toxic chemicals developed for use by the military, but used by terrorists against civilian populations. As threats of terrorism increase, it is possible that health care providers will be confronted with multiple victims of nerve agent exposure. Nerve agents are highly toxic forms of organophosphate poisons that potentially could cause harm to anyone who comes in contact. Emergency personnel need to be familiar with the agents, know how to prepare for encountering and treating victims, and know how to protect all people involved from further poisoning.

Nerve gas-induced seizures: role of acetylcholine in the rapid induction of Fos and glial fibrillary acidic protein in piriform cortex

Soman (pinacolymethylphosphonofluoridate), a highly potent irreversible inhibitor of acetylcholinesterase (AChE), causes seizures and rapidly increases Fos and glial fibrillary acidic protein (GFAP) staining in piriform cortex (PC). This suggests that the inhibition of AChE by soman leads to increased acetylcholine (ACh) and neuronal excitability in PC. The sole source of cholinergic input to PC is from the nucleus of the diagonal band (NDB). To investigate the role of ACh in soman-induced seizures, we lesioned cholinergic neurons in NDB unilaterally with 192-IgG-saporin. By 10 d, saporin eliminated staining for choline acetyltransferase (ChAT), the synthetic enzyme for ACh, in NDB ipsilateral to the lesion. Staining for AChE, the degradative enzyme for ACh, was eliminated in PC ipsilateral to the lesioned NDB. By 45-60 min after soman, increased Fos and GFAP staining in PC was evident only ipsilateral to the unlesioned NDB. By 90-120 min after soman, Fos and GFAP staining increased bilaterally in PC. In a second experiment, electrical stimulation electrodes were implanted unilaterally in the NDB to activate focally the projections to PC in unanesthetized rats. Within 5 min of NDB stimulation, there were clear behavioral and EEG signs of convulsions. After 45-60 min of NDB stimulation, there was increased Fos and GFAP staining in layer II of PC ipsilateral to the stimulation site. Pretreatment with the selective muscarinic receptor antagonist scopolamine blocked the convulsions and prevented increased Fos and GFAP staining in PC. These results suggest that ACh release in PC triggers the initiation of seizures and gliosis after soman administration, predominantly by the activation of muscarinic receptors.