2. Human Biomonitoring
Biomonitoring is a valuable tool for assessing human exposures to chemical contaminants in the environment. Biomonitoring tests can be divided into biomarkers of exposure, effect, and susceptibility. In studies of community exposure to an environmental contaminant, biomarkers of exposure are most often used. The ideal biomarker should be sensitive, specific, biologically relevant, practical, inexpensive, and readily available. Seldom does a biomarker meet all of these criteria, and most biomarkers represent a compromise. In designing a community exposure study, consideration should also be given to the selection of the test population, the practicality of collecting biological samples, temporal or seasonal variations in exposure, the availability of background comparison ranges, and interpretation of the test results. Biomonitoring tests provide unequivocal evidence of exposure, but they do not typically identify the source of exposure. Furthermore, rarely do the test results predict a health outcome. For many chemicals, testing must be conducted soon after exposure has occurred. In spite of these limitations, the use of biomonitoring is finding wider application in many scientific disciplines. Recent advances in analytical techniques are expanding the utility of biomarker testing in public health investigations [13
Biological indicators or biomarkers generally include biochemical, molecular, genetic, immunologic, or physiological signals of events in biological systems. The events are depicted as a flow chart between an external exposure to a chemical and resulting clinical effects [14
The endpoint of biological monitoring is often referred to as a biomarker, defined as “a change induced by a contaminant in the biochemical or cellular components of a process, structure or function that can be measured in a biological system” [15
]. Since biomarkers lie on a flow chart (Figure 2
), it may be difficult to delineate between biomarkers of exposure and effect [16
Simplified flow chart of classes of biomarkers [17
Simplified flow chart of classes of biomarkers [17
3.1. Biomarkers of Exposure
Biomarkers of exposure have been defined as “a chemical or its metabolite, or the product of an interaction between a chemical and some target molecule or cell that is measured in an organism” [18
]. It has been suggested, that an ideal biomarker of exposure should be “specific for a chemical, detectable in small quantities, measured by non-invasive techniques, inexpensive, associated with prior exposure and have an excellent positive predictive value to a specific disease status” [19
]. Indeed, it is a hard task to discover biomarkers of exposure for various toxic chemicals that address all criteria above. However, many biomarkers have been identified and used in occupational surveys of exposure to various chemicals [20
It is generally assumed, that the longer the half-life of a marker, the better it can be correlated with effects resulting from chronic, long-term, low-level exposure to cumulative toxicants. When investigating possible exposure of toxic compounds, the choice of biomarker should depend on how long after suspected exposure the sampling was performed.
3.1.2. Adducts to Macromolecules or DNA
The calculated grade of binding to proteins (such as hemoglobin or albumin) or DNA (usually in lymphocytes) is useful as a biomarker, particularly when assessing exposure to genotoxic compounds, because it reflects the dose that has avoided detoxification and reached its target protein or DNA [24
]. Because the life span of red blood cells is comparatively long (approximately 4 months), binding to hemoglobin is considered a good biomarker to measure repeated exposure or exposure that occurred weeks or even months before sampling [25
Albumin has a shorter life-time in blood (20–25 days) and these adducts will thus reflect more recent exposures. One advantage of albumin is that toxic compounds can directly react with this protein when reaching the blood without having to penetrate a cell membrane before forming an adduct [19
Although macromolecule adducts seem like ideal biomarkers of effect, it should be mentioned that adduct measurements are difficult to perform and to standardize, and are limited to compounds or metabolites forming adducts.
3.2. Biomarkers of Effect
A biomarkers of effect has been defined as “A measurable biochemical, physiologic, behavioral, or other alternation in an organism that, depending on the magnitude, can be recognized as associated with an established or possible health impairment or disease” [20
]. It has been suggested, that ideal biomarkers of exposure should meet criteria such as non-invasiveness, sensitivity and reflect early responses that precedes functional damage. Analytical methods must be reproducible, easy to perform and applicable to a large number of samples.
Biomarkers of effect may be of value in hazard identification and dose-response assessment. In hazard identification, biomarkers may facilitate screening and/or identification of a toxic agent and characterization of the associated toxicity.
The lack of validation of most biomarkers of intermediate effect is probably the most common argument against broad use of biomarkers in risk assessment. However, efforts to validate biomarkers are rapidly generating a large amount of data measuring intermediate effects occurring after exposure and before illness. Therefore, they should identify early and reversible biochemical events that may also be predictive of later response [23
]. However, altered physiology is also considered as relevant biomarkers of exposure. The further to the right in the flow chart (Figure 2
) the biomarker is, the greater the clinical or health relevance of its measurement. An abnormal value of a biomarker of effect near the centre of the flow chart may not signal negative effects on the health of an individual or group if, for example, the cause is reversible and steps are taken to ensure that the exposure that caused it ceases [15
Unfortunately, the mechanism of action of many toxic chemicals is unknown at present. Furthermore, there are individual variations in the response to equivalent doses of chemicals. While the outcome of a chemical insult in an individual may be predicted more accurately from biomarkers of effect(s), such biomarkers may not be specific for a single causative agent. Nevertheless, many biomarkers of effect are used in everyday practice to assist in clinical diagnosis. Therefore, most biomarkers of effect have been identified starting from clinical conditions, extrapolating backward to document changes or exposure preceding illness (e.g., early markers of nephrotoxicity that was discovered in the clinic). However, clinical alterations can hardly be interpreted in terms of toxicity in the absence of experimental models, providing some mechanistic clues. Therefore, numerous experimental animal and cellular studies have contributed to the attempts to identify new biomarkers of effect.
Prospective epidemiological studies are also often used for validation of the effect of biomarkers. This type of study provides estimates of the risk of disease of individuals using monitoring of particular biomarkers. Such a strategy is suitable when the outcome is relatively frequent, and the measured biomarker is inexpensive and readily available, e.g., serum cholesterol in cardiovascular disease [27
3.3. Biomarkers of Susceptibility
An individual’s susceptibility to environmentally mediated disease may arise from genetic causes or from non-genetic factors such as age, concomitant disease state, diet, or dietary supplementation.
Genetic polymorphisms may be markers of susceptibility. The rapid advances of the Human Genome and Environmental Genome projects are generating a long list of genes and their variants (polymorphisms). Research is helping us to understand which genes are perturbed on the pathway to disease. Many of these genes are quite general in their function and broadly applicable to the assessment of susceptibility. Such genes or groups of genes will, for example, influence or control cell differentiation, apoptosis, cell cycle kinetics, or DNA repair. Receptor-mediated pathways involving alterations in signal transduction can influence a variety of health outcomes. There is a spectrum of human genetic variability such that a distribution of responses to a given exposure can sometimes be predicted.
New technologies such as microchip arrays allow researchers to explore patterns of gene expression. In the face of this burgeoning information and data being gathered by the National Institutes of Health and in other databases, the challenge for researchers interested in environmentally mediated disease or risk assessment is to understand the functionality of genetic polymorphisms and to relate this to disease. We may gain this understanding in humans, particularly by relating laboratory, clinical, and epidemiologic findings. To date, most genetic susceptibility studies have looked at cancers as an end point, although research on other diseases such as asthma is beginning to grow. As our understanding of functionality grows, so will our need for understanding of the ethical implications of our knowledge to individuals and society [15
Human Biological Monitoring (HBM) has long been used in occupational health as part of a preventive strategy in the medical surveillance of workers. Currently it is increasingly used as a tool in environmental health policy. More than the classical environmental measurements, pollution gets personal [30
]. HBM not only provides valuable information on exposure and its possible effects on health, but also has great impact in raising awareness for possibilities of prevention, and serves as a basis for establishing and evaluating policy measures.
Besides its strong points, HBM clearly has its limitations, including challenging logistical problems and important ethical concerns. Test results are often poorly related to possible health outcomes. They provide only a snapshot of substances present in the body at a single point in time and do not provide information about the source or history of exposure. A long delay may also exist between the availability of test results, the identification of the impact on health and the prospect for measures [30
]. Therefore, much work needs to be done, in particular with respect to the proper interpretation of HBM data and its translation into policy actions. Research should allow for a more appropriate use of HBM in the prevention of diseases by further validation of HBM procedures, establishment of relations between biological monitoring parameters and early indicators of disease, development of scenarios for translation into policy, progress in effect monitoring, and provision of better conditions for HBM programs (development of less invasive biomarkers, development of strategies for communication by professionals, setting up the appropriate legal conditions, etc
The future success depends on a twofold approach: thorough evaluation of the biomarkers that have been found to be useful in various settings [4
] and search for new biomarkers [1
]. The former is not always easy and hence much attention has been spent on the latter bringing new technologies to bear to look for new biomarkers (see Table 1
and Table 2
). A marker may be good in one clinical setting, but not in another. The very best biomarkers will be useful in many contexts. Networks of scientists and clinicians should be used to evaluate multiple biomarkers simultaneously. Another very important feature of the utility of biomarkers is that they must be easy to analyze rapidly and preferably at the bedside if clinical decision-making is to be optimally affected by them.
Example of chemicals, biomarkers of exposure and health effects.
Example of chemicals, biomarkers of exposure and health effects.
|Nerve Agents||Red blood cell or serum cholinesterase EEG changes||Whole blood||Diffuse muscle cramping, runny nose, difficulty breathing, eye pain, dimming of vision, sweating, muscle tremors, loss of consciousness, seizures, flaccid paralysis.|
|Cyanides||Cyanide or thiocyanate||Blood or urine||Giddiness, palpations, dizziness, nausea, vomiting, headache, eye irritation, increase in rate and depth of breathing (hyperventilation), drowsiness, loss of consciousness, convulsions and death.|
|Vesicants/Blister Agents||Thiodiglycol||Urine||Burning, itching, red skin, mucosal irritation, shortness of breath, nausea and vomiting|
|Ricin||Ricinine||Urine, respiratory secretions, serum, and direct tissue||Nausea, diarrhea, vomiting, fever, abdominal pain, chest tightness, coughing, weakness, nausea, fever|
|Benzene||Benzene, Phenol||Blood, exhaled air, urine||Confusion, sleepiness, rapid pulse, loss of consciousness, anemia, damage to the nervous system, suppression of the immune system, carcinogenic, death|
|Carbon monoxide (CO)||Hematologic biomarkers of coagulation and inflammation.||Blood||Tissue hypoxia, headache, nausea, vomiting, dizziness, blurred vision, cardiac arrhythmias, myocardial ischemia, cardiac arrest, hypotension, respiratory arrest, noncardiogenic pulmonary edema, seizures, and coma.|
|Nitrogen dioxide||Nitrate, pentane||Urine, breath||Wheezing, coughing, colds, flu and bronchitis|
|Sulfur dioxide||S-sulfonate||Blood||Lung function changes, life-threatening|
|Polycyclic aromatic hydrocarbons (PAHs)||PAH metabolites||Urine||Pulmonary, gastrointestinal, renal, and dermatologic systems, carcinogenic|
|Organic Gases (Volatile Organic Compounds—VOCs)||VOC’s or metabolites||Breath, blood, urine||Allergic sensitization or asthmatic symptoms, carcinogenic|
Examples of radiation biomarker assays and exposure assessment methods.
Examples of radiation biomarker assays and exposure assessment methods.
|Assay||Dose range (Gy)||Specificity||Induction time||Persistence||Speed of analysis||Field amenable||Automation potential|
|Dicentric Assay||0.2–5||High||Hours||Several months||2+ days||No||Partial|
|MN Assay||0.3–5||Mod.–low||Hours||Several months||3+ days,||No||Yes|
|PCC Assay||ND–20+||High–mod.||Hours||Several months||2+ days||No||Partial|
|Gene markers||Variable, ~0.2–5||Low||Variable Hours–days||Variable Hours—days||<1 day||Possible||Possible|
|Protein markers||Variable, ~0.5–20+||Low||Variable Hours–days||Variable Hours—days||<1 day||Possible||Possible|
|Blood cell kinetics||1–10||Low||Immediate||Up to 2 weeks||Days||Yes||Yes|
|Bioassay *||<0.001||High||NA||Variable||<1 day||No||Yes|
4. Chemical Exposure and Effects on Specific Organs
4.1. Chemicals Affecting the Respiratory Tract
Many toxic chemicals can damage the respiratory airways, with potentially life-threatening effects. Ammonia, various alkalis (e.g., bleach and sodium hydroxide), hydrochloric and sulfuric acid, vesicants (e.g., sulfur mustard) and other corrosive agents affect the upper airways, the portion of the respiratory tract that begins at the mouth and nose and ends at the larynx (voice box). Inhalation of these chemicals can cause acute inflammation, painful ulcerations, increased secretions, and difficulties in breathing and swallowing. Secondary bacterial infections may further exacerbate the initial injury. Damage to the upper airway can lead to respiratory failure and death. Exposure can also lead to long-term health problems. For example, chronic respiratory problems, such as scarring and narrowing of the trachea, have been observed in Iranians exposed to sulfur mustard during the Iran-Iraq War of the 1980s (vesicating chemicals will be discussed in more detail in the section entitled “Chemicals Affecting the Skin, Eyes, and Mucous Membranes”).
Some industrial chemicals, including ammonia, chlorine, phosgene, and per-fluoro-isobutylene (PFIB) can cause lower respiratory tract injuries, particularly life-threatening pulmonary edema. Pulmonary edema—the leakage of fluid into the lungs—prevents oxygen delivery to the blood, ultimately preventing oxygen from reaching the brain, kidneys, and other organs. Symptoms may be immediate or delayed; chlorine causes immediate airway irritation and pain, whereas phosgene exposure may not be evident for 24 to 48 hours [32
]. People who survive a single, acute exposure to respiratory airway toxicants generally show little or no long-term health problems, although some may eventually develop asthma or chronic bronchitis. Individuals at greatest risk are those with pre-existing heart or lung disease.
4.1.1. Diagnostic Tools
Current diagnostic capabilities are limited. Exposure to chlorine, phosgene, or any of the major alkalis is determined based on clinical signs and symptoms. No screening tests are available to identify individuals exposed to low levels of chemicals.
Mechanistic studies may also aid in the development of new diagnostic approaches. Some chemicals generate metabolic byproducts that could be used for diagnosis, but detection of these byproducts may not be possible until many hours after initial exposure. Additional research needs to be directed at developing sensitive and specific tests to identify individuals quickly after they have been exposed to varying levels of chemicals toxic to the respiratory tract.
One way to approach the diagnostic problems is by development of lung-specific biomarkers. When the integrity of the lung epithelium is broken, lung-specific proteins may leak into the blood circulation. The appearance of such proteins in peripheral blood may indicate lung injury. Clara cell protein 16 and lung surfactant D are two proteins that are produced predominantly in the lungs and therefore have been proposed as biomarkers of public health lung diseases.
Clara cell protein 16 (CC16) is a protein which is secreted in large amounts at the surface of airways from where it leaks into the serum, most likely by passive diffusion. It acts as an immunosuppressant and provides protection against oxidative stress and carcinogenesis. The serum concentration of CC16 is a new sensitive marker to detect an increased permeability of the epithelial barrier, which is one of the earliest signs of lung injury. It has been detected in a variety of both clinical and experimental situations such as exposure to smoke, chlorine, lipopolysaccharides and ozone and is indeed a promising biomarker for this area of research. It is important though to consider that serum levels of CC16 are not specific to one agent, disease state or exposure—it is merely an indication of lung injury [33
Surface protein D (SPD) is a large, multimeric protein produced mainly by cells of the lungs. It plays an important role in innate immunity and in host defense responses. Over-expression of SPD has been associated with chronic inflammatory conditions such as asthma and interstitial pulmonary fibrosis and chronic obstructive pulmonary disease (COPD) [34
When exposed to chemical agents it is very likely that the lungs are affected. Inhalation of toxic substances can cause serious injuries both in the acute phase but can also cause chronic damages. It is therefore very important to quickly be able to evaluate the severity of the damage in order to treat it correctly. Common markers for inflammation are cytokines in lung tissue, lavage fluid or serum. By a simple blood sample it is possible to run an assay (ELISA or Bioplex) which gives information on which cytokine levels that are elevated and the inflammation can be treated and monitored over time.
The collection of exhaled breath condensate (EBC) is a simple and non-invasive technique to measure mediators of airway inflammation. It is portable which makes it good for field studies [35
]. In EBC exhaled and cooled aerosol droplets serve as seeds for condensation resulting in liquid phase accumulation. EBC does not affect the airway in contrast to bronchial biopsy, bronchoalveolar lavage and induced sputum. There are two groups if inflammatory biomarkers in EBC which are of most importance; eicosanoids and cytokines. Eicosanoids, such as 8-isoprotane, are formed by lipid peroxidation of arachidonic acid during oxidative stress. Cytokines are small proteins involved in mediating inflammation and tissue repair. Cytokine concentrations in EBC samples are usually quantified by enzyme-linked immunosorbent assay (ELISA).
One of the current limitations of EBC measurements is the low concentration of many biomarkers which makes it difficult to perform measurements. It is likely that even more sensitive assays will be able as more potent antibodies are developed and new molecular techniques are introduced [36
Proteomics, which applies high resolution gel electrophoresis or mass spectrometry (MS) to detect multiple proteins in biological samples, may also be useful to analyze the proteins in EBC.
Exhaled nitric oxide (eNO) is a reliable marker of airway inflammation. The measurement is easy to perform and the result is immediately available. Increased levels of eNO have been measured in patients with respiratory diseases such as asthma and COPD. Therefore it is believed that eNO could be used as a noninvasive biomarker of respiratory inflammation [37
]. It is particularly attractive because the test requires little effort from the patient, can be measured even in young children and the result of the test can be immediately available.
4.2. Chemicals Affecting the Skin, Eyes and Mucous Membranes
Vesicating agents such as sulfur mustard, nitrogen mustard, lewisite, and caustic industrial chemicals can cause severe blistering and burns to the eyes, mucous membranes, skin, and upper airways, as well as chronic eye inflammation and blindness. The eyes are the organs most sensitive to these chemicals. Vesicants may also affect other parts of the body, including the respiratory tract, immune system, and bone marrow. Sulfur mustard can cause tissue damage within minutes of exposure. Physical injury from other vesicating agents may not be evident for several hours and may result in delayed recognition of exposure [38
]. In such situations, an exposed individual may put others at risk of secondary contamination.
The immediate symptoms of exposure to one of these chemicals includes: coughing followed by difficulty breathing/shortness of breath and possibly fluid in lungs within 2–6 hours; burning sensation in the throat and eyes accompanied with watery eyes and blurred vision; nausea and vomiting and developing skin lesions.
The exposure may cause delayed effects even if the person has no clinical symptoms. These includes: difficulty with breathing and shortness of breath and coughing up white to pink-tinged fluid; low blood pressure; heart failure and chronic bronchitis.
4.3. Chemicals Affecting the Nervous System
A variety of chemicals are known to affect the nervous system. Some directly target neural signaling pathways. These include the classic nerve agents (e.g., sarin, soman, tabun, and VX) [39
]; organophosphate pesticides [40
] and some animal toxins (e.g., botulinum toxin). Chemicals can also affect the nervous system indirectly. For example, metabolic poisons (e.g., cyanide) disrupt cellular respiration, which ultimately prevents the brain from getting sufficient oxygen and energy. Some vesicating agents (e.g., sulfur mustard) appear to have neurological effects as well, although the specific mechanism by which they affect the nervous system is poorly understood.
Neurological symptoms depend on the type of chemical, the level of exposure, and the time elapsed following exposure. Exposure to nerve agents, metabolic poisons, or high levels of sulfur mustard can trigger seizures and loss of consciousness. Other acute effects of nerve agent poisoning include muscle paralysis, cardio respiratory depression, and massive secretion from mucous membranes, eye irritation (miosis), and blurry or dim vision. Other acute effects of exposure to high doses of sulfur mustard include behavioral effects and cognitive difficulties. Nerve agents and metabolic poisons also appear to have serious long-term neurological effects, including neuronal degeneration, but these have not been studied extensively.
The physical states of chemicals that affect the nervous system are an important determinant of the requirements for developing effective countermeasures. Although some chemicals that affect the nervous system exist primarily in the form of a vapor (e.g., hydrogen cyanide), others are oily liquids that are very difficult to remove from the environment and extremely toxic even at miniscule levels (e.g., VX). For these persistent agents, it would be ideal to have pretreatments with long-lasting protective effects that can be administered in advance of possible exposure to personnel who must enter contaminated sites.
5. Radiation Exposure and Health Effects
Nuclear and radiological scenarios can result in several different types of radiation exposures that range from external exposure to penetrating radiation (such as γ- and x-ray sources) to exposure from internalized radionuclides. The primary concern from α-emitting radionuclides is internal contamination since the range of the α-particle is very short and cannot penetrate the dead layer of the skin but can deliver a significant dose to tissues in the body if internalized. The range of β-particles is longer and dependent on the energy of the emission. If deposited on the skin, radiations burns can result from the energy deposited and absorbed in the skin and β-emitting radionuclides pose a significant health hazard if internalized. The impact of γ- or x-ray emitting nuclides, or penetrating radiation, depend on the activity of the source. High activity sources can result in cutaneous effects, which are often localized. Some dose can be received from internalized γ-emmitting nuclides, however, the primary concern in most scenarios is from high doses received externally.
5.1. Radiation Injury
A whole body, or significant partial body, external exposure to penetrating radiation (>1 Gy) delivered in a short time from, i.e.
, at a high dose rate, will result in specific signs and symptoms termed acute radiation syndrome (ARS) [44
]. The four phases of ARS include prodromal, latent, manifest, and recovery or death. The prodromal phase occurs in the first 48 hours and occasionally up to 6 days. The latent phase is characterized by a short, transient period of time (few days to a few weeks) where patients demonstrate some recovery by being less affected by symptoms. Manifest illness then follows which may continue for several weeks, and is dominated by immunosuppression. The final phase will be recovery or death, dependent on the dose and other factors such as the individual’s age, existence of other injuries, etc
The focus of this discussion is primarily on acute, high dose exposures from external sources and the acute effects observed after such exposures. However, it is important to note that other injuries and latent effects can occur from radiation exposure. In the case of internalized radionuclides, specific organ damage can occur to any organ in which the radionuclide accumulates in or is retained in. For example, α-emitting, insoluble plutonium and americium radionuclides can be retained in the lungs for a long time after inhalation exposure. Once incorporated into the body, they accumulate in the bone. Therefore, these nuclides can significantly impact pulmonary tissue, resulting pneumonitis or fibrosis, and the red bone marrow resulting in impaired hematopoietic function. Latent effects that can result from radiation exposures include cataract formation and increased cancer risk.
5.2. Organ System Effects
Specific symptoms, their onset and severity are highly dependent on absorbed radiation dose. Proliferating cells are most sensitive to radiation and hence exhibit acute effects. As such, hematopoietic stem cells and intestinal crypt cells are inherently sensitive and result in clinical effects that predominate in a predictable range of doses [45
]. The specific syndromes manifested in ARS include the neuro/cerebrovascular, hematopoietic, gastrointestinal, and cutaneous systems.
The neurovascular or cerebrovascular system will exhibit symptoms, the degree of which varies depending on the dose received. In fact, the onset of nausea and vomiting has been used to estimate dose and is well correlated. Fatigue, fever, headache, hypotension, as well as neurological and cognitive deficits can be observed [46
]. At very high doses (≥30 Gy), cerebrovascular syndrome occurs. Immediate nausea, vomiting, hypotension, ataxia, and convulsions may occur soon after exposure, followed by unconsciousness and death within days [47
]. The origin of some of these symptoms relate to changes in permeability in the blood brain barrier and vasculature system.
Symptoms observed in from the gastrointestinal system include diarrhea, abdominal cramps, and pain resulting from losses in the mucosal layer in the gut. Gastrointestinal syndrome occurs with doses in the range of 6–20 Gy due to death of the intestinal stem cells causing hemorrhaging. In this dose range, prompt onset of nausea, vomiting, and diarrhea will be observed followed by recurrence of gastrointestinal symptoms after the latent phase. Sepsis can occur from gut flora leaking into the systemic circulation. Intestinal bleeding, electrolyte imbalance, and death may follow, usually in 8–10 days.
The hematopoietic system will exhibit in general an initial rise in some cells, followed by a decline. Lymphocytes, granulocytes, and thrombocytes are all affected. The depletion of neutrophils will result in increased susceptibility to infection while thrombocyte depletion can result in hemorrhaging. Hematopoietic syndrome occurs at whole body doses of 2–10 Gy due to bone marrow depression and is most strikingly characterized by lymphocyte depletion. Blood cell depletion kinetics can be used to indicate dose and facilitate prognosis. Many persons can survive ARS if treated with fluids, antibiotics, and blood products. If standard care is performed, death generally results only when there are no surviving stem cells in the red bone marrow.
The cutaneous system also exhibits effects after radiation exposure [48
]. Onset and degree of erythema and epilation has been correlated with radiation dose. At very high doses, swelling, blistering, and desquamation can occur. While cutaneous syndrome is not generally a stand-alone mechanism of mortality, it contributes the overall systemic response to radiation and has been implicated in contributing to multi-organ failure [49
]. Furthermore, radiation burns from localized radiation deposition on the skin significantly contributed to the observed mortality in Chernobyl victims.
With successful treatment of high dose radiation exposure and ARS, late effects may be observed in other organs. For example, the lungs and kidneys exhibit damage months after the exposure due to chronic inflammation leading to fibrosis or necrosis. Some cases can result in multi-organ dysfunction and failure.
5.3. Diagnosis and Assessment
The appropriate treatment of radiation injury is highly dependent on accurate diagnosis and assessment. Current methods used for determining radiation dose include any physical dose estimates or reconstruction of the exposure, clinical signs and symptoms, blood cell kinetics, and cytogenetic biodosimetry. A simple system for using the collective diagnostic information to rapidly and reliably classify acute radiation injury for managing treatment, termed Radiation Injury Severity Classification (RISC), has been described [50
]. The system was adapted from previously described injury groups [51
] to address special concerns in management of mass casualty events. A similar approach for medical radiation assessment and management which extensively describes diagnostic approaches based on organ specific parameters has been developed as part of an EU project termed METREPOL (Medical Treatment Protocols for Radiation Accident Victims) [46
Radiation assessment is only one part of the overall decision for treatment of an individual. Subsequently, all available knowledge concerning the affected persons(s) such as the existence of other injuries, age, health status, and dose will be used in determining eventual treatment and therapy.
5.3.1. Signs and Symptoms
The onset of clinical signs and symptoms can be reliably used to assess the extent of radiation dose (see Table 3
). Some of the symptoms expected after significant radiation exposure (>1 Gy) include headache, nausea, vomiting, and diarrhea. At very high whole body or local skin doses (>6 Gy), cutaneous effects such as erythema can be observed, as well as seizures and incapacitation above 10 Gy. Of these symptoms, the most useful and reproducible parameter for assessing dose is the time to emesis or vomiting. A very high dose is assessed with onset of these symptoms within one hour, and significant dose with onset within 2–4 hours. However, the exact time of exposure must be known in order to accurately determine the lapse time before onset. In accident scenarios and in the presence of other significant injuries, onset of vomiting
may be influenced by shock and trauma. In this case, a reliable dose estimate may not be possible based on this parameter. The following assessments are primarily valid for whole body doses [45
Signs and symptoms correlated with absorbed radiation dose [54
Signs and symptoms correlated with absorbed radiation dose .
| ||Onset of Symptom|| |
|ARS/ Dose||Vomiting||Diarrhea||Headache||Consciousness||Medical care|
|Mild (1–2 Gy)||>2 hr||-||Slight||-||Outpatient|
|Mod. (2–4 Gy)||1–2 hr||-||Mild||-||Hospital|
|Severe (4–6 Gy)||<1 hr||Mild, 3–8 hr||Mod., >24hr||-||Special hosp.|
|Very sev. (6–8 Gy)||<30 min||Heavy, 1–3 hr||Severe, 3–4 hr||Possible||Specialized hospital|
|Lethal (>8 Gy)||<10 min||Heavy, <1 hr|| ||Sec.–minutes||Palliative care|
5.3.2. Blood Cell Kinetics
Since the hematopoietic system is one of the more sensitive organs to radiation, blood cells parameters can be valuable tools in estimating dose. However, the methods discussed again apply primarily to whole body exposures and assessments will not be valid for partial body exposures [55
]. These endpoints are further limited by the natural variability in individual baseline cell counts and sensitivities.
If initiated early, serial blood cell counts can provide a reasonable estimate of dose as well as an indication of the treatments needed and eventual prognosis. A specific pattern of blood cell changes may be observed in the first couple of weeks after exposure and can help to provide a clear picture of the hematological response [56
]. These changes involve decreases and increases in granulocytes, platelets, and lymphocytes. Granulocytes may transiently rise before neutropenia (severe decrease of neutrophilic granulocytes) begins [44
]. In some cases, granulocytes may experience an abortive rise around day 5–10, which is indicative of residual, viable hematopoietic tissue capable of reproducing granulocytes. Lymphocytes decline rapidly and later repopulate if the radiation dose is not too extreme where bone marrow or stem cell transplantation is warranted. Platelets may have an initial shoulder before decline or begin a progressive decline within the first week depending on dose [57
The parameter most often used and recommended for aiding dose estimation is the kinetics of lymphocyte depletion. In the best case, complete blood cell counts with determination of the leukocyte differential are obtained immediately and followed up 2–3 times per day over the first week [45
]. The rate of the lymphocyte decline is highly dependent upon the radiation dose received and can be used to estimate exposure based on the slope obtained from the differential counts. Ideally, blood cell counts are followed until the nadir in the neutrophil count is established. In assessment of blood cell kinetics, some researchers recommend considering both lymphocyte and neutrophil counts or their ratio as an indicator of dose [50
Utilization of additional hematological information (i.e.
, granulocyte, lymphocyte, and platelet counts) affords a better diagnosis and facilitates prognosis since the changes observed indicate the effect on the blood stem cell pool which can aid the prediction of eventual recovery or existence of irreversible injury [57
]. If irreversible injury has occurred, definitive care such as stem cell replacement is warranted if other injuries are minimal and the dose is not too great.
The most established method used as a radiation biological dosimeter is cytogenetic analysis of chromosomal aberrations by the measure of dicentric aberrations in metaphases from blood lymphocytes (see Table 4
Dicentric chromosomes frequency expected in human lymphocytes resulting from different radiation doses [45
Dicentric chromosomes frequency expected in human lymphocytes resulting from different radiation doses .
|Dose Estimate||Dicentrics in peripheral blood lymphocytes|
|Per 50 cells (triage)||Per 1000 cells|
The dicentric assay is currently the gold standard in biodosimetry [58
]. A blood sample should be obtained at least 24 hours after exposure, followed by lymphocyte cell culture, and subsequent analysis. The time from sample acquisition to dose estimate is typically 2–3 days. If the radiation event involves a large number of individuals, analysis on a triage basis may be performed. This method evaluates fewer cells in the analysis to provide a more general estimate of dose category. The dicentric frequency observed in the patient is standardized by an in vitro
dose-response curve specific for different types of radiation. The frequency of dicentric aberrations is well correlated with dose and may be used to prepare a dose estimate. Over-dispersion of aberration frequency can be used to provide an estimate of partial body dose with the use of mathematical models. However, for certain inhomogeneous exposure events, cytogenetic dosimetry is ineffective. Examples of such situations are exposure to β-emitting radionuclides deposition on the skin and incorporation of many radionuclides that accumulate in specific organs and tissues. Altough internalized caesium-137 has more or less uniform distribution in the body and may be an exeption [6
The dicentric assay is reliable only up to 5 Gy due to cell death and saturation of the dose response curve at higher doses [60
]. Another cytogenetic assay using chemical phosphatase inhibitors to induce premature chromosome condensation (PCC) has been applied reliably at doses up to 20 Gy [61
], the utility of which was demonstrated during the Tokai-mura criticality accident [62
] and provides a good alternative for evaluation of higher doses of radiation exposure. The PCC assay can provide valuable complementary information for medical treatment decisions since with present advances in modern medicine, the critical decisions concerning definitive care in acute radiation injury is in the dose range above 5 Gy.
Other cytogenetic methods include the micronucleus assay and analysis of stable translocations by fluorescence in situ
hybridization (FISH). Micronuclei are formed when chromosomes fail to segregate properly at mitosis and appear in the cytoplasm. The method requires a longer incubation time than the dicentric assay but requires less analysis time because the cells are easier to evaluate. At low doses, the micronucleus method is uncertain, since micronuclei also are produced by other clastogens resulting in a higher background frequency. Additionally, coalescence may occur at high doses causing a flattening of the dose-response curve [63
]. Fluorescence in situ
hybridization (FISH) has been developed for retrospective analyses to complement the shorter halflife dicentrics in the lymphocyte pool. FISH proved efficacious in detecting stable translocations between chromosomes [64
]. Persistent translocations may provide a retrospective estimate of stem cell dose many years later [65
]. Its value has been demonstrated when significant time has elapsed between radiation exposure and the discovery of that exposure [54
5.3.4. Dose Reconstruction
In many cases, physical dose estimates are not available or will be only a rough estimate for a single individual involved in a large accident. However, when available and when time allows, physical dose reconstruction of dose may be very valuable since eventual prognosis concerning whole body radiation exposure is highly associated with the absorbed dose estimate. In some cases, dose reconstruction methods can be applied to estimate the partial body equivalent dose when partial body exposures have occurred or in cases where part of the body has been shielded. This greatly facilitates medical management decisions since shielding of the lung or essential parts of the bone marrow will greatly impact the chance of survival for an exposed individual.
5.3.5. Future Diagnostics
Unfortunately, the methods described above are inadequate for the diagnostic evaluation of radiation exposure in a mass casualty scenario. None of the methods are suitably fast, high-throughput, or field amenable for use in the field for triage sorting and application for making emergency care decisions. However, several methods currently under development may be able to address this gap.
The γH2AX foci analysis is based on measurement of a histone-related protein that forms a variant form of H2A, which codes the DNA [68
]. Double strand breaks in the DNA caused by ionizing radiation results in phosphorylation of H2AX adjacent to the number of double strand breaks [69
]. Antibodies specific fluorescent staining of the phosphorylated form of H2AX, termed γH2AX foci, allows observation and quantification of DNA damage. There is a good relation between γH2AX foci and DNA damage up to ~5 Gy. Currently, γH2AX foci are counted manually by microscopic analysis, but efforts are underway to develop high throughput analyses, potentially using flow cytometry and other means.
Gene expression signatures are also a potential alternative for radiation dose assessment. Microarrays embedded on chips for genomic profiling may afford a potentially fast and high-throughput technique. This procedure monitors the gene expression profile of cells that can detect 2–3 fold changes in gene expression between samples. The specific genes which expression changes following radiation exposure have been identified. Recent work suggests that the technique has potential applicability for dosimetry estimations [70
]. A linear dose-response for induction of several genes has been observed as low as 0.02 Gy. In a recent study on human peripheral blood from healthy donors, a 74-gene signature was identified that distinguishes between radiation doses (0.5–8 Gy) and control. Expression patterns of five genes (CDKN1A, FDXR, SESN1, BBC3 and PHPT1) from this signature were also confirmed by real-time PCR. The authors were able to on a single set of genes, predict radiation dose at both 6 and 24 hours after exposure without the need for pre-exposure sample, which is an important advance for gene expression biodosimetry. The separation by exposure dose was clearest between the lower doses with some overlap evident between the highest doses of 5 and 8 Gy. An effect of time since the radiation was also evident in the 74-gene signature. Inter-individual variation is another important concern for the development of gene expression biomarkers. Within a set of ten donors used by Amundsen et al
, variations by radiation exposure dose were greater than the variations in expression between donors, allowing relative accurate classification of samples by dose. In a recent study of radiation induced gene expression in human peripheral lymphocytes using real-time PCR, there was a minimal variance of base line expression and consistent radiation responses among five genes between 20 healthy donors [75
]. Gene expression signatures are looking increasingly attractive as potential biodosimeters for radiation exposure. However, further validation in terms of in vivo
responses in cancer patients and animal models, inter-individual variability, radiation specificity of the signatures is still needed. In order to make gene expression signatures practically useful for mass casualty screening, they will also be needed to be exported from the laboratory-based microarray platforms currently used for discovery research to higher throughput forward deployable platforms. Approaches have been suggested based on q-RT-PCR [76
] and nano-technology “lab-on-a-chip” designs [77
Similar to gene expression profiling, proteomic and metabolomic profiling also hold promise as alternative methods for radiation dose assessment. To exploit current advances in the ability to monitor changes in protein expression to identify a biomarker radiation exposure, it is necessary to quantify the protein expression changes and relate them to dose or establish dose-dependent panel of such changes. A number of techniques are available to examine protein profiles including higher resolution surface-enhanced laser desorption ionization time of flight mass spectrometry (SELDI-TOF MS), [78
]. The approach has been tested in cancer patients before and during radiotherapy and the exposed population could be distinguished from the unexposed population with high sensitivity and specificity. In the analyses 23 protein fragments/peptides were uniquely detected in the exposed group. This shows that the protein profile in serum changes following radiation exposure in a manner that is probably dose-dependent. The approach requires further development and a defined dose-response relationship remains to be determined. Identification of radiation-induced metabolic changes and an understanding of the signaling pathways involved are necessary for development of a reliable metabolomic marker to assess radiation exposure and extent of injury. Using state-of-the-art HPLC MS (TOF), the entire human metabolome has been illustrated as a feasible compartment to analyse the metabolome with respect to radiation dose.
An initial assessment is required to establish the necessary treatment protocol for injured patients involving radiation. Triage is performed so that patients may be sorted according to the urgency of care required. In mass casualty situations, patients are further sorted to optimally match patient needs to limited resources.
5.4.1. Radiation Independently
When radiation injury is encountered without other types of wounds, triage is focused on diagnosis and establishment of dose estimate. If any internal radiation contamination exists, decontamination and decorporation treatment should begin as early as possible since some nuclides can become lodged in tissues. The specific therapies for patients after a radiological accident are highly dependent on the dose and overall patient assessment. However, in general, the hematopoietic syndrome and resulting immune-suppression are the immediate priorities in treatment of radiation-only injuries. Treatment of hematopoietic syndrome involves predominately administration of fluids and antibiotics. The use of cytokines to stimulate hematopoietic cell proliferation has been proposed but must be initiated within the first 24–48 hours to be effective. At higher doses gastrointestinal effects can be observed but few treatment options exist for these effects. The final dose cut-off for effective treatment is in the dose range where eventual fibrosis of the lung will evolve (~10 Gy).
5.4.2. Combined with Trauma and/or Wounds
In many scenarios, radiation injury will be accompanied by burns, wounds, and trauma resulting from a blast. During the triage stage, all life threatening injuries should be prioritized and handled first. If a contamination is an issue after a patient is stabilized, decontamination and decorporation therapy can be considered. Thereafter, burns and wounds should be prioritized. If surgery is required, this should take place in the first two days after exposure. Establishment of radiation dose during this period will indicate the need for other measures such as supportive care and in some cases isolation. The prognosis of irradiated patients with combined injuries is much poorer than those with radiation alone. The changes in the traditional triage classification when combined with radiation are shown in Table 5
Triage categories for combined injuries dependent on radiation dose [45
Triage categories for combined injuries dependent on radiation dose .
|Conventional triage category||Changes in triage category with whole body radiation|
|<1.5 Gy||1.5–4.5 Gy||>4.5 Gy|
5.5. Emergency Care
After an initial triage, patients should be sorted into treatment categories with patients having exposures less than 1 Gy not normally requiring further treatment and those with greater than 10 Gy receiving supportive and palliative care since fatal outcome is anticipated. In general, this stage of care is for patients that have received significant but non-lethal doses of radiation. Treatment actions in this phase generally address the symptoms resulting from hematopoietic syndrome.
Chemical or radiological mass casualties call for rapid and robust diagnostic technologies (Figure 3
). These should determine, monitor and assist in handling of the exposed. As indicated in this review the development of new and improved medical technologies utilizing recent developments within medicine, biotechnology and intelligent communication technology (ICT) is foreseen. New insights into useful biomarkers and the development of useful analytical technologies or concepts are reciprocally dependent and driven by “curiosity” or scientific incitements. Sometimes the scientific push giving new biomarkers or new analytical technology also results in medically useful devices.
The intrinsic logistics of such development towards different diagnostic tools is simplified in the block diagram below.
The intrinsic logistics of such development towards different diagnostic tools is simplified in the block diagram below.
These devices are basically analytical instruments calibrated and somewhat modified to better serve their intended medical purpose and to be a useful property of the advanced hospital laboratory. Diagnostic tools as indicated in the figure, refers to mass produced (i.e., relatively cheap) simplified instruments that may serve as a standalone capability in acute care or in primary medical care. These are dedicated to simple routine analyses, such as blood glucose assessments. Finally, the triage tool is the instrument similarly dedicated to emergency medicine and mass casualties. It must be robust, simple, efficient and cheap in order to be produced and implemented. The development of diagnostic and/or triage tools will depend on commercial realities. If there is a market, these tools will eventually appear when the technological advancements so allow. If the market is lacking, which is the case for such rare events as mass emergencies, such development has to be politically augmented and realized through public investments.
The present review deals with the prospect of and need for diagnostic or triage tools when handling mass casualty situations following the exposure to toxic chemicals or radiation. The development of diagnostic principles for radiation damage and/or signs of intoxication have been dealt with in parallel. Obviously, the support and need for diagnostic tools within such professions as nuclear medicine, hematology and oncology has been larger than the corresponding support for development of diagnostic tools for intoxication. Biomarkers and diagnostically useful methods have, therefore, been developed for the assessment of dose effects and radiation injuries. None of these methods have as yet become a candidate for triage tool development. The development of diagnostic tools for intoxication is lagging behind. There may have been less support and/or need for this development and, indeed, there are less professionals involved in issues of intoxications in a clinical setting, i.e., involved in triage like situations.
This review underlines the relative maturity of the underpinning science, i.e., about biomarkers, analytical procedures and miniaturization. The challenge now is to develop diagnostic assays, diagnostic tools and triage tools based on bodily fluids and/or cells that assess chemical exposure or already absorbed doses of ionizing radiation or deposited internal radiological contamination and simplified and miniaturized into useful triage tools. At the same time, diagnostic technologies assessing physiological functions that are altered by e.g., chemical or radiological exposures has to be developed as an integral tool in the medical management of casualties. In the end this becomes a question of resources and priorities. Making our society more resilient towards accidental or intentional release of toxic chemicals or radioactive material has to become an issue of high priority.
The authors acknowledge the financial support of DG Sanco of the European Union. They also acknowledge the contribution of all partners to the MASH project, i.e., The European CBRNE Center, Sweden, The Karolinska Institute (KI), Sweden, Umeå University Sweden, The Swedish Defense Research Agency (FOI), Sweden, The Health Protection Agency (HPA), UK, The Service Aide Medicale Aide Urgence de Paris (SAMU), France, The Armed Forces Institute of Radiobiology (InstRadBioBw), Germany, The University of Ulm, Germany and The Centro De Estudios E Investigaciones Tecnicas De Gipuzkoa (CEIT), Spain.
Conflict of Interest
The authors declare no conflict of interest.
- Lapierre, D.; Moro, J. Five Past Midnight in Bhopal; Warner Books: New York, NY, USA, 2002. [Google Scholar]
- Van Sickle, D.; Wenck, M.A.; Belflower, A.; Drociuk, D.; Ferdinands, J.; Holguin, F.; Svendsen, E.; Bretous, L.; Jankelevich, S.; Gibson, J.J.; et al. Acute health effects after exposure to chlorine gas released after a train derailment. Am. J. Emerg. Med. 2009, 27, 1–7. [Google Scholar] [PubMed]
- Morita, H.; Yanagisawa, N.; Nakajima, T.; Shimizu, M.; Hirabayashi, H.; Okudera, H.; Nohara, M.; Midorikawa, Y.; Mimura, S. Sarin poisoning in Matsumoto, Japan. Lancet 1995, 346, 290–293. [Google Scholar]
- Cassel, G.; Eriksson, H.; Sandström, B. MASH scenarios, 2008; EU MASH project 2007209. In Proceedings of the 18th Nuclear Medical Defence Conference and EU-MASH-Symposium, Munich, Germany, 11–12 February 2009.
- The Radiological Accident in Goiânia; STI/PUB/815; International Atomic Energy Agency (IAEA): Vienna, Austria, 1988.
- Yardley, J. Indian man dies after radiation exposure. N. Y. Times 2010, A6. [Google Scholar]
- Oberemm, A.; Onyon, L.; Gundert-Remy, U. How can toxicogenomics inform risk assessment? Toxicol. Appl. Pharmacol. 2005, 207, 592–598. [Google Scholar] [CrossRef] [PubMed]
- Wang, Z.; Gerstein, M.; Snyder, M. RNA-Seq: A revolutionary tool for transcriptomics. Nat. Rev. Genet. 2009, 10, 57–63. [Google Scholar]
- Bandara, L.R.; Kennedy, S. Toxicoproteomics—A new preclinical tool. Drug Discov.Today 2002, 7, 411–418. [Google Scholar]
- Nicholson, J.K.; Lindon, J.C. Systems biology: Metabonomics. Nature 2008, 455, 1054–1056. [Google Scholar]
- Bioinformatics. Wikipedia Web site. 2011. Available online: http://en.wikipedia.org/wiki/Bioinformatic (accessed on 28 April 2004).
- Marazuela, D.; Moreno-Bondi, M.C. Fiber-optic biosensors—An overview. Anal. Bioanal. Chem. 2002, 372, 664–682. [Google Scholar]
- Metcalf, S.W.; Orloff, K.G. Biomarkers of exposure in community settings. J. Toxicol. Environ. Health 2004, 67, 715–726. [Google Scholar]
- Validation. In Molecular Epidemiology: Principles and Practices; Schulte, P.A.; Perera, F.P. (Eds.) Academic Press: San Diego, CA, USA, 1993; pp. 79–107.
- National Academy of Science, National Research Council (NRC), Biologic Markers in Reproductive Toxicology; National Academy Press: Washington, DC, USA, 1989; pp. 15–34.
- Morgan, M.S. The biological exposure indices: A key component in protecting workers from toxic chemicals. Environ. Health Perspect. 1997, 105, 105–115. [Google Scholar]
- NRC CoBMotNRC. Biological markers in environmental health research. Environ. Health Perspect. 1987, 74, 3–9.
- WHO, Biomarkers in Risk Assessment: Validity and Validation (EHC 222); WHO Library Cataloguing-in-Publication: Geneva, Switzerland, 2001.
- Henderson, R.F.; Bechtold, W.E.; Bond, J.A.; Sun, J.D. The use of biological markers in toxicology. Crit. Rev. Toxicol. 1989, 20, 65–82. [Google Scholar]
- NRC, Human Biomonitoring for Environmental Toxicants: Human Biomonitoring for Environmental Chemicals; National Academy Press: Washington, DC, USA, 2006; pp. 84–131.
- Aitio, A.; Kallio, A. Exposure and effect monitoring: A critical appraisal of their practical application. Toxico. Lett. 1999, 108, 137–147. [Google Scholar]
- Watson, W.P.; Mutti, A. Role of biomarkers in monitoring exposures to chemicals: Present position, future prospects. Biomarkers 2004, 9, 211–242. [Google Scholar]
- Mutti, A.; Mazzucchi, A.; Rustichelli, P.; Frigeri, G.; Arfini, G.; Franchini, I. Exposure-effect and exposure-response relationships between occupational exposure to styrene and neuropsychological functions. Am. J. Ind. Med. 1984, 5, 275–286. [Google Scholar]
- Ehrenberg, L.; Osterman-Golkar, S. Alkylation of macromolecules for detecting mutagenic agents. Teratog. Carcinog. Mutagen. 1980, 1, 105–127. [Google Scholar]
- Costa, L.G. Biomarker research in neurotoxicology: The role of mechanistic studies to bridge the gap between the laboratory and epidemiological investigations. Environ. Health Perspect. 1996, 104, 55–67. [Google Scholar]
- Silbergeld, E.K. Neurochemical approaches to developing biochemical markers of neurotoxicity: Review of current status and evaluation of future prospects. Environ. Res. 1993, 63, 274–286. [Google Scholar]
- Wald, N.J.; Law, M.R. Serum cholesterol and ischaemic heart disease. Atherosclerosis 1995, 118, S1–S5. [Google Scholar]
- Bennett, D.A.; Waters, M.D. Applying biomarker research. Environ. Health Perspect. 2000, 108, 907–910. [Google Scholar]
- Perbellini, L.; Veronese, N.; Princivalle, A. Mercapturic acids in the biological monitoring of occupational exposure to chemicals. J. Chromatogr. B Analyt. Technol. Biomed. Life Sci. 2002, 781, 269–290. [Google Scholar]
- Stokstad, E. Biomonitoring. pollution gets personal. Science 2004, 304, 1892–1894. [Google Scholar] [CrossRef] [PubMed]
- Angerer, J. Biological monitoring in occupational and environmental medicine—The present state of the art and future prospects. In DFG Biological Monitoring. Prospects in Occupational and Environmental Medicine; Wiley-VCH: Weinheim, Germany, 2002; pp. 5–15. [Google Scholar]
- Borak, J.; Diller, W.F. Phosgene exposure: Mechanisms of injury and treatment strategies. J. Occup. Environ. Med. 2001, 43, 110–119. [Google Scholar]
- Lomas, D.A.; Silverman, E.K.; Edwards, L.D.; Miller, B.E.; Coxson, H.O.; Tal-Singer, R. Evaluation of serum CC-16 as a biomarker for COPD in the ECLIPSE cohort. Thorax 2008, 63, 1058–1063. [Google Scholar]
- Sin, D.D.; Leung, R.; Gan, W.Q.; Man, S.P. Circulating surfactant protein D as a potential lung-specific biomarker of health outcomes in COPD: A pilot study. BMC Pulm. Med. 2007, 7, 13:1–13:7. [Google Scholar]
- Rosias, P.P.; Robroeks, C.M.; Niemarkt, H.J.; Kester, A.D.; Vernooy, J.H.; Suykerbuyk, J.; Teunissen, J.; Heynens, J.; Hendriks, H.J.; Jöbsis, Q.; et al. Breath condenser coatings affect measurement of biomarkers in exhaled breath condensate. Eur. Respir. J. 2006, 28, 1036–1041. [Google Scholar] [PubMed]
- Horváth, I.; Hunt, J.; Barnes, P.J.; Alving, K.; Antczak, A.; Baraldi, E.; Becher, G.; van Beurden, W.J.; Corradi, M.; Dekhuijzen, R.; et al. Exhaled breath condensate: Methodological recommendations and unresolved questions. Eur. Respir. J. 2005, 26, 523–548. [Google Scholar] [CrossRef] [PubMed]
- Birrell, M.A.; McCluskie, K.; Hardaker, E.; Knowles, R.; Belvisi, M.G. Utility of exhaled nitric oxide as a noninvasive biomarker of lung inflammation in a disease model. Eur.Respir. J. 2006, 28, 1236–1244. [Google Scholar]
- Greenfield, R.A.; Brown, B.R.; Hutchins, J.B.; Iandolo, J.J.; Jackson, R.; Slater, L.N.; Bronze, M.S. Microbiological, biological, and chemical weapons of warfare and terrorism. Am. J. Med. Sci. 2002, 323, 326–340. [Google Scholar] [CrossRef] [PubMed]
- Bajgar, J. Complex view on poisoning with nerve agents and organophosphates. Acta Medica (Hradec Kralove) 2005, 48, 3–21. [Google Scholar] [PubMed]
- Costa, L.G.; Giordano, G.; Guizzetti, M.; Vitalone, A. Neurotoxicity of pesticides: A brief review. Front Biosci. 2008, 13, 1240–1249. [Google Scholar]
- Wang, J.; Timchalk, C.; Lin, Y. Carbon nanotube-based electrochemical sensor for assay of salivary cholinesterase enzyme activity: An exposure biomarker of organophosphate pesticides and nerve agents. Environ. Sci. Technol. 2008, 42, 2688–2693. [Google Scholar] [PubMed]
- Christodoulides, N.; Tran, M.; Floriano, P.N.; Rodriguez, M.; Goodey, A.; Ali, M.; Neikirk, D.; McDevitt, J.T. A microchipbased multianalyte assay system for the assessment of cardiac risk. Anal. Chem. 2002, 74, 3030–3036. [Google Scholar]
- Wong, D.T. Salivary diagnostics powered by nanotechnologies, proteomics and genomics. J. Am. Dent. Assoc. 2006, 137, 313–321. [Google Scholar]
- Weisdorf, D.; Chao, N.; Waselenko, J.K.; Dainiak, N.; Armitage, J.O.; McNiece, I.; Confer, D. Acute radiation injury: Contingency planning, triage, supportive care, and transplantation. Biol. Blood Transpl. 2006, 12, 672–682. [Google Scholar] [CrossRef]
- Waselenko, J.K.; MacVittie, T.J.; Blakely, W.F.; Pesik, N.; Wiley, A.L.; Dickerson, W.E.; Tsu, H.; Confer, D.L.; Coleman, C.N.; Seed, T.; et al. Medical management of the acute radiation syndrome: Recommendations of the strategic national stockpile radiation working group. Ann. Intern. Med. 2004, 140, 1037–1051. [Google Scholar] [PubMed]
- Fliedner, T.M.; Friesecke, I.; Beyrer, K. Medical Management of Radiation Accidents: Manual on the Acute Radiation Syndrome; British Institute of Radiology: London, UK, 2001. [Google Scholar]
- Koenig, K.L.; Goans, R.E.; Hatchett, R.J.; Mettler, F.A., Jr.; Schumacher, T.A.; Noji, E.K.; Jarrett, D.G. Medical treatment of radiological casualties: Current concepts. Ann. Emerg. Med. 2005, 46, 643–652. [Google Scholar]
- Peter, R.U.; Gottlöber, P. Management of cutaneous radiation injuries: Diagnostic and therapeutic principles of the cutaneous radiation syndrome. Mil. Med. 2002, 167, 110–112. [Google Scholar]
- Meineke, V. The role of damage to the cutaneous system in radiation-induced multi-organ failure. Br. J. Radiol. 2005, S27, 95–99. [Google Scholar]
- Kuniak, M.; Azizova, T.; Day, R.; Wald, N.; Suyama, J.; Zhang, A.; Sumina, M.V.; Pesternikova, V.S.; Vasilenko, E.; Soaita, A.; et al. The radiation injury severity classification system: An early injury assessment tool for the frontline health-care provider. Br. J. Radiol. 2008, 81, 232–243. [Google Scholar] [CrossRef] [PubMed]
- Thoma, G.E.; Wald, N. The diagnosis and management of accidental radiation injury. J. Occup. Med. 1959, 1, 421–447. [Google Scholar]
- Berger, M.E.; Christensen, D.M.; Lowry, P.C.; Jones, O.W.; Wiley, A.L. Medical management of radiation injuries: Current approaches. Occup. Med. 2006, 56, 162–172. [Google Scholar]
- Epelman, S.; Hamilton, D.R. Medical mitigation strategies for acute radiation exposure during spaceflight. Aviat. Space Environ. Med. 2006, 77, 130–139. [Google Scholar]
- Diagnosis and Treatment of Radiation Injuries; STI/PUB/1040; International Atomic Energy Agency (IAEA): Vienna, Austria, 1998.
- Chao, N.J. Accidental or intentional exposure to ionizing radiation: Biodosimetry and treatment options. Exp. Hemat. 2007, 35, 24–27. [Google Scholar]
- Blakely, W.F.; Salter, C.A.; Prasanna, P. Early-response biological dosimetry—Recommended countermeasure enhancements for mass-casualty radiological incidents and terrorism. Health Phys. 2005, 89, 494–504. [Google Scholar]
- Fliedner, T.M.; Graessle, D.; Meineke, V.; Dörr, H. Pathophysiological principles underlying the blood cell concentration responses used to assess the severity of effect after accidental whole body radiation exposure: An essential basis for an evidence based clinical triage. Exp. Hemat. 2007, 35, 8–16. [Google Scholar]
- Cytogenetic Analysis for Radiation Dose Assessment: A Manual; STI/DOC/010/405; International Atomic Energy Agency (IAEA): Vienna, Austria, 2001.
- Lloyd, D.C.; Edwards, A.A.; Prosser, J.; Auf der Maur, A.; Etzweiler, A. Accidental intake of tritiated water: A report of two cases. Radiat. Prot. Dosim. 1986, 15, 191–196. [Google Scholar]
- Lloyd, D.C.; Edwards, A.A. Chromosome aberrations in human lymphocytes: Effect of radiation quality, dose, and dose rate. In Radiation-induced Chromosome Damage in Man; Ishihara, T., Sasaki, M.S., Alan, R., Eds.; Liss Inc.: New York, NY, USA, 1983; pp. 23–49. [Google Scholar]
- Kanda, R.; Hayata, I.; Lloyd, D.C. Easy biodosimetry for high-dose radiation exposures using drug-induced, prematurely condensed chromosomes. Int. J. Radiat. Biol. 1999, 75, 441–446. [Google Scholar]
- Hayata, I.; Kanda, R.; Minamihisamatsu, M.; Furukawa, A.; Sasaki, M. Cytogenetical dose estimation for 3 severely exposed patients in the JCO criticality accident in Tokai-mura. J. Radiat. Res. 2001, 42, S149–S155. [Google Scholar]
- Littlefield, L.G.; Sayer, A.M.; Frome, E.L. Comparisons of dose-response parameters for radiationinduced acentric fragments and micronuclei observed in cytokinesis-arrested lymphocytes. Mutagenesis 1989, 4, 265–267. [Google Scholar] [CrossRef] [PubMed]
- Pinkel, D.; Straume, T.; Gray, J.W. Cytogenetic analysis using quantitative, high-sensitivity, fluorescence hybridization. Proc. Natl. Acad. Sci. USA 1986, 83, 2934–2938. [Google Scholar]
- Edwards, A.A.; Lindholm, C.; Darroudi, F.; Stephan, G.; Romm, H.; Barquinero, J.; Barrios, L.; Caballin, M.R.; Roy, L.; Whitehouse, C.A.; et al. Review of translocations detected by FISH for retrospective biological dosimetry applications. Radiat. Prot. Dosimetry. 2005, 113, 396–402. [Google Scholar] [CrossRef] [PubMed]
- The Radiological Accident in Istanbul; STI/PUB/1102; International Atomic Energy Agency (IAEA): Vienna, Austria, 2000.
- Sevan’kaev, A.V.; Lloyd, D.C.; Edwards, A.A.; Moquet, J.E.; Nugis, V.Y.; Mikhailova, G.M.; Potetnya, O.I.; Khvostunov, I.K.; Guskova, A.K.; Baranov, A.E.; et al. Cytogenic investigations of serious overexposures to an industrial gamma radiography source. Radiat. Prot. Dosimetry 2002, 102, 201–206. [Google Scholar] [PubMed]
- Paull, T.T.; Rogakou, E.P.; Yamazaki, V.; Kirchgessner, C.U.; Gellert, M.; Bonner, W.M. A critical role for histone H2AX in recruitment of repair factors to nuclear foci after DNA damage. Curr. Biol. 2000, 10, 886–895. [Google Scholar]
- Rogakou, E.P.; Boon, C.; Redon, C.; Bonner, W.M. Megabase chromatin domains involved in DNA double-strand breaks in vivo. J. Cell. Biol. 1999, 146, 905–916. [Google Scholar] [PubMed]
- Amundson, S.A.; Bittner, M.; Meltzer, P.; Trent, J.; Fornace, A.J., Jr. Biological indicators for the identification of ionizing radiation exposure in humans. Expert Rev. Mol. Diagn. 2001, 1, 211–219. [Google Scholar]
- Amundson, S.A.; Bittner, M.; Meltzer, P.; Trent, J.; Fornace, A.J., Jr. Induction of gene expression as a monitor of exposure to ionizing radiation. Radiat. Res. 2001, 156, 657–661. [Google Scholar]
- Amundson, S.A.; Fornace, A.J., Jr. Monitoring human radiation exposure by gene expression profiling: Possibilities and pitfalls. Health Phys. 2003, 85, 36–42. [Google Scholar]
- Amundson, S.A.; Bittner, M.; Fornace, A.J., Jr. Functional genomics as a window on radiation stress signaling. Oncogene 2003, 22, 5828–5833. [Google Scholar]
- Amundson, S.A.; Grace, M.B.; McLeland, C.B.; Epperly, M.W.; Yeager, A.; Zhan, Q.; Greenberger, J.S.; Fornace, A.J., Jr. Human in vivo radiation-induced biomarkers: Gene expression changes in radiotherapy patients. Cancer Res. 2004, 64, 6368–6371. [Google Scholar] [PubMed]
- Grace, M.B.; Blakely, W.F. Transcription of five p53- and Stat-3-inducible genes after ionizing radiation. Radiat. Meas. 2007, 42, 1147–1151. [Google Scholar]
- Grace, M.B.; McLeland, C.B.; Gagliardi, S.J.; Smith, J.M.; Jackson, W.E., 3rd.; Blakely, W.F. Development and assessment of a quantitative reverse transcription-PCR assay for simultaneous measurement of four amplicons. Clin. Chem. 2003, 49, 67–75. [Google Scholar]
- Liu, R.H.; Yang, J.; Lenigk, R.; Bonanno, J.; Grodzinski, P. Self-contained, fully integrated biochip for sample preparation, polymerase chain reaction amplification, and DNA microarray detection. Anal. Chem. 2004, 76, 1824–1831. [Google Scholar] [PubMed]
- Ménard, C.; Johann, D.; Lowenthal, M.; Muanza, T.; Sproull, M.; Ross, S.; Gulley, J.; Petricoin, E.; Coleman, C.N.; Whiteley, G.; et al. Discovering clinical biomarkers of ionizing radiation exposure with serum proteomic analysis. Cancer Res. 2006, 66, 1844–1850. [Google Scholar] [PubMed]
- TMT Handbook: Triage, Monitoring and Treatment of People Exposed to Ionising Radiation Following a Malevolent Act; Rojas-Palma, C.; Liland, A.; Jerstad, A.N.; Etherington, G.; Perez, M.R.; Rahola, T.; Smith, K. (Eds.) Norwegian Radiation Protection Authority: Österås, Norway, 2009.
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