Bioanalysis and Analytical Services Research Group at The Municipal Institute for Medical Research IMIM-Hospital del Mar, Spain

Analytical laboratories involved in health-related research are becoming a fundamental part of the advancement of science in this field. Of particular interest to clinical, legal, toxicological, forensic and environmental matters is the analysis of drugs and medications present in biological fluids of consumers or exposed subjects. The established sensitive and reliable work of sports drug-testing laboratories represents an interesting example of a multidisciplinarity approach toward widespread bioanalytical problems. The experiences reported in this article will be of general interest, especially for analysts studying the determination of substances in biological material.     

Orthogonal predictions: follow‐up questions for suggestive data

When a biological hypothesis of causal effect can be inferred, the hypothesis can sometimes be tested in the selfsame database that gave rise to the study data from which the hypothesis grew. Valid testing happens when the inferred biological hypothesis has scientific implications that predict new relations between observations already recorded. Testing for the existence of the new relations is a valid assessment of the biological hypothesis, so long as the newly predicted relations are not a logical correlate of the observations that stimulated the hypothesis in the first place. These predictions that lead to valid tests might be called ‘orthogonal’ predictions in the data, and stand in marked contrast to ‘scrawny’ hypotheses with no biological content, which predict simply that the same data relations will be seen in a new database. The Universal Data Warehouse will shortly render moot searches for new databases in which to test. Copyright © 2010 John Wiley & Sons, Ltd.     

Barrett's oesophagus—cancer risk, biology and therapeutic management

Barrett's oesophagus is receiving increasing scrutiny as the rates of adenocarcinoma of the oesophagus rise. Because clinical features are not predictive of the presence of Barrett's oesophagus and most individuals with Barrett's oesophagus go undetected, a case can be made for surveillance endoscopy in patients with chronic reflux. Once Barrett's oesophagus is diagnosed patients should be entered into a surveillance programme despite lack of proof of efficacy. Scientific study of putative biological markers of increased risk has added dramatically to the understanding of the biology of the lesion, but currently the finding of high-grade dysplasia remains the best marker predicting the presence of greatly increased risk of developing cancer. It is likely that newer molecular biology techniques will become clinically applicable biological markers in the future. Currently there is no effective medical nor surgical therapy to cause regression of the metaplastic Barrett's epithelium, however the application of novel de-differentiating agents or ablation of the metaplastic epithelium while controlling oesophageal acid exposure and other environmental abnormalities offer hope that effective treatment of Barrett's oesophagus may someday be reality.     

Critical aspects in reproductive and developmental toxicity testing of environmental chemicals

The process of toxicity testing of environmental chemicals is ruled by a framework of guidelines (OECD, OPPTS, etc.). The present paper will describe the process from the biological tests for environmental chemicals up to potential labelling and will focus on some critical aspects in this cascade of events. It is also the aim of this paper to give an overview of the existing documents and draft documents relevant for this field and available in the internet. Based on the current situation, the following points are discussed as critical issues: life stage considerations and their implications on testing, usefulness of investigations in juvenile animals, requirements for ADME studies, design and endpoints in fertility studies, use and usefulness of developmental milestones, performance of special studies versus one-study-design, considerations on transplacental carcinogenicity and early aging, significance of maternal/parental toxicity, application of triggers to justify studies, inclusion of new endpoints into test guidelines, and test strategies applied. Based on this, the usefulness of risk considerations in the current EU classification system for toxicity to reproduction as well as potency considerations will be discussed and suggestions will be made to improve the basic requirements for chemical testing which have remained relatively unchanged over the past 20 years.     

Review article: molecular basis of gastric carcinogenesis

Gastric cancer is constituted by two histomorphological entities 'intestinal' and 'diffuse', however lesions with similar morphologies may differ in biological aggressiveness and response to therapy. Two distinct molecular pathways have been identified in gastric carcinogenesis: the microsatellite mutator phenotype and a phenotype associated with chromosomal and intrachromosomal instability. Mounting evidence suggests that microsatellite mutator phenotype alterations and expression of the products of cancer-related genes are early markers of cell transformation, and may serve to identify the gastric carcinoma histotypes. The lack of a clear genetic basis, lends weight to the notion that gastric cancer is not a monomorphic entity but may be affected by environmental factors. Helicobacter pylori is the most important environmental risk factor associated with sporadic gastric cancer. Exposure of gastric epithelial cells to bacterium results in the generation of reactive oxygen species and inducible nitric oxide synthase that in turn may cause genetic alterations leading to cancer in a subset of subjects. Thus, gastric cancer may be considered the result of an interplay between host genetic profile and environmental toxic agents. The new technologies of molecular analysis will help to establish an individual's risk of developing gastric cancer and will lead to novel biological therapeutic strategies.     

The threshold problem in ecotoxicology

The most commonly used threshold in environmental toxicology is the LC₅₀ (or modifications thereof) where 50% of the organisms die or are otherwise affected at a certain concentration of a chemical for a particular time of exposure under specified environmental conditions. Most commonly, this particular threshold is derived from single species laboratory tests low in environmental realism. If the field of ecotoxicology truly examines the effects of chemicals on ecosystems (i.e., complex multivariate systems), serious consideration must be given to thresholds other than those now commonly used in the field of environmental toxicology. Attributes at the community and ecosystem level of organization are not demonstrated at lower levels of biological organization, for example, energy flow and nutrient spiralling. Key issues are whether extrapolation is possible from one threshold to another within a level of biological organization and from one level of biological organization to another for thresholds that do not exist at many levels. Thresholds may be artefacts of testing procedures and may not exist in natural systems. Nevertheless, society must make management decisions about risk with available methods, including those designed to identify some point or threshold below which no deleterious effects are observed. However, these methods and their assumptions deserve more explicit and systematic examination than they have received thus far.     

Computational toxicology--a state of the science mini review.

Advances in computer sciences and hardware combined with equally significant developments in molecular biology and chemistry are providing toxicology with a powerful new tool box. This tool box of computational models promises to increase the efficiency and the effectiveness by which the hazards and risks of environmental chemicals are determined. Computational toxicology focuses on applying these tools across many scales, including vastly increasing the numbers of chemicals and the types of biological interactions that can be evaluated. In addition, knowledge of toxicity pathways gathered within the tool box will be directly applicable to the study of the biological responses across a range of dose levels, including those more likely to be representative of exposures to the human population. Progress in this field will facilitate the transformative shift called for in the recent report on toxicology in the 21st century by the National Research Council. This review surveys the state of the art in many areas of computational toxicology and points to several hurdles that will be important to overcome as the field moves forward. Proof-of-concept studies need to clearly demonstrate the additional predictive power gained from these tools. More researchers need to become comfortable working with both the data generating tools and the computational modeling capabilities, and regulatory authorities must show a willingness to the embrace new approaches as they gain scientific acceptance. The next few years should witness the early fruits of these efforts, but as the National Research Council indicates, the paradigm shift will take a long term investment and commitment to reach full potential.     

Twin studies of alcohol consumption, metabolism and sensitivity

It is a common observation that individuals differ greatly in their consumption of alcohol and, if they do drink, in their sensitivity to it. Comparison of identical (MZ) and non-identical (DZ) twins is perhaps the best available design for estimating the relative contributions of environmental and genetic factors to individual differences. We have studied drinking habits in 3,810 adult twin pairs who responded to a mailed questionaire. Genetic factors are of major importance in determining the alcohol consumption of females of all ages but are modified in their expression by marriage. They are also important in young males but are overshadowed by environmental influences shared by brothers as they get older. In a laboratory study of alcohol metabolism and psychomotor sensitivity in more than 200 twin pairs we found heritabilities of 0.62 for peak BAC and 0.49 for rate of elimination. These did not differ significantly from their respective test-retest reliabilities, which were surprisingly low, indicating the importance of short-term environmental influences on ethanol metabolism. For certain psychomotor tests, particularly body sway, we found evidence that sensitivity to alcohol was strongly genetically determined. However, only 2 per cent of variance was accounted for by blood alcohol concentration. Two possible interpretations of our results are :- i) the psychomotor tests we have used have little to do with driving competence and therefore our results are irrelevant for practical purposes, or ii) roadside tests of driving competence will be a more effective preventive measure than measuring concentrations of alcohol or other drugs in the blood.     

The metabolism and toxicity of quinones,quinonimines, quinone methides,and quinone-thioethers

Quinones are ubiquitous in nature and constitute an important class of naturally occurring compounds found in plants, fungi and bacteria. Human exposure to quinones therefore occurs via the diet, but also clinically or via airborne pollutants. For example, the quinones of polycyclic aromatic hydrocarbons are prevalent as environmental contaminants and provide a major source of current human exposure to quinones. The inevitable human exposure to quinones, and the inherent reactivity of quinones, has stimulated substantial research on the chemistry and toxicology of these compounds. From a toxicological perspective, quinones possess two principal chemical properties that confer their reactivity in biological systems. Quinones are oxidants and electrophiles, and the relative contribution of these properties to quinone toxicity is influenced by chemical structure, in particular substituent effects. Modification to the quinone nucleus also influences quinone metabolism. This review will therefore focus on the differences in structure and metabolism of quinones, and how such differences influence quinone toxicology. Specific examples will be discussed to illustrate the diverse manner by which quinones interact with biological systems to initiate and propagate a toxic response.     

Comparison of three rapid toxicity test procedures: Microtox,® polytox,® and activated sludge respiration inhibition

Methods for measuring respiratory activity can detect adverse effects on heterotrophic microorganisms. These methods are useful tools for assessing the impact of chemicals on biological wastewater treatment processes. They are also well suited for evaluating the treatability potential of individual wastes. However, varying results are often reported when using municipal or industrial activated sludge substrate in toxicity assessments. The lack of reproducibility of these tests has also greatly limited efforts to measure the effectiveness of treatment plants in removing toxic contaminants. The toxicity of waste-waters and chemicals to biological treatment systems can be determined in 30 min with the new Polytox® toxicity procedure. The Polytox® kit utilizes a specialized blend of bacterial cultures. The objective of this paper is to evaluate the relative sensitivity of the new Polytox® toxicity procedure with two accepted microbial assay procedures; namely, the Microtox® bioluminescence assay and the Organization for Economic Cooperation and Development's Activated Sludge Respiration Inhibition test. This paper compares toxicity values for selected inorganic and organic chemicals as determined in the three microbial assay systems. The sensitivity and reliability of the new Polytox® toxicity procedure is discussed.     

Inorganics and Hormesis

The article is a comprehensive review of the occurrence of hormetic dose-response relationships induced by inorganic agents, including toxic agents, of significant environmental and public health interest (e.g., arsenic, cadmium, lead, mercury, selenium, and zinc). Hormetic responses occurred in a wide range of biological models (i.e., plants, invertebrate and vertebrate animals) for a large and diverse array of endpoints. Particular attention was given to providing an assessment of the quantitative features of the dose-response relationships and underlying mechanisms that could account for the biphasic nature of the hormetic response. These findings indicate that hormetic responses commonly occur in appropriately designed experiments and are highly generalizeable with respect to biological model responses. The hormetic dose response should be seen as a reliable feature of the dose response for inorganic agents and will have an important impact on the estimated effects of such agents on environmental and human receptors.     

Inorganics and hormesis

The article is a comprehensive review of the occurrence of hormetic dose-response relationships induced by inorganic agents, including toxic agents, of significant environmental and public health interest (e.g., arsenic, cadmium, lead, mercury, selenium, and zinc). Hormetic responses occurred in a wide range of biological models (i.e., plants, invertebrate and vertebrate animals) for a large and diverse array of endpoints. Particular attention was given to providing an assessment of the quantitative features of the dose-response relationships and underlying mechanisms that could account for the biphasic nature of the hormetic response. These findings indicate that hormetic responses commonly occur in appropriately designed experiments and are highly generalizeable with respect to biological model responses. The hormetic dose response should be seen as a reliable feature of the dose response for inorganic agents and will have an important impact on the estimated effects of such agents on environmental and human receptors.     

The ecotoxicology of nanoparticles and nanomaterials: current status,knowledge gaps,challenges, and future needs

This paper introduces a special issue on the ecotoxicology and environmental chemistry of nanoparticles (NPs), and nanomaterials (NMs), in the journal Ecotoxicology. There are many types of NMs and the scientific community is making observations on NP ecotoxicity to inform the wider debate about the risks and benefits of these materials. Natural NPs have existed in the environment since the beginning of Earth's history, and natural sources can be found in volcanic dust, most natural waters, soils and sediments. Natural NPs are generated by a wide variety of geological and biological processes, and while there is evidence that some natural NPs can be toxic, organisms have also evolved in an environment containing natural NPs. There are concerns that natural nano-scale process could be influenced by the presence of pollution. Manufactured NPs show some complex colloid and aggregation chemistry, which is likely to be affected by particle shape, size, surface area and surface charge, as well as the adsorption properties of the material. Abiotic factors such as pH, ionic strength, water hardness and the presence of organic matter will alter aggregation chemistry; and are expected to influence toxicity. The physico-chemistry is essential to understanding of the fate and behaviour of NPs in the environment, as well as uptake and distribution within organisms, and the interactions of NPs with other pollutants. Data on biological effects show that NPs can be toxic to bacteria, algae, invertebrates and fish species, as well as mammals. However, much of the ecotoxicological data is limited to species used in regulatory testing and freshwater organism. Data on bacteria, terrestrial species, marine species and higher plants is particularly lacking. Detailed investigations of absorption, distribution, metabolism and excretion (ADME) remain to be performed on species from the major phyla, although there are some data on fish. The environmental risk assessment of NMs could be performed using the existing tiered approach and regulatory framework, but with modifications to methodology including chemical characterisation of the materials being used. There are many challenges ahead, and controversies (e.g., reference substances for ecotoxicology), but knowledge transfer from mammalian toxicology, colloid chemistry, as well as material and geological sciences, will enable ecotoxicology studies to move forward in this new multi-disciplinary field.     

Animals as monitors of environmental quality.

The various species of domesticated and wild animals can be excellent monitors of environmental quality. Although analyses of industrial air and water effluents and tests for toxicants in soils, plants, foods and feeds may provide some degree of predictability of environmental quality, the ultimate monitors are those organisms having metabolic activities that are comparable to man. If we closely observe animals that share our environment, like the coal miner's canary, they will alert us to unseen and perhaps devastating environmental hazards.     

The power and interpretation of the carcinogenicity bioassay

Carcinogenicity is a major consideration in the assessment of risks due to environmental chemicals. The carcinogen bioassay therefore is a very important component of the battery of toxicological tests used in hazard evaluation. The strengths and limitations of this bioassay are discussed with emphasis upon the unresolved practical considerations, the interpretation of negative results, the significance of tumors induced in the presence of a high background incidence of naturally occurring tumors, and the difficulties in transspecies extrapolation. These factors, in combination with consideration of the biological mechanisms of chemical cancer induction, will be valuable in assessing the potential risk to man posed by individual chemicals.     

CONCENTRATIONS OF ARSENIC,CADMIUM, COPPER,LEAD, MERCURY,AND ZINC IN HUMAN PLACENTAS FROM TWO CITIES IN UKRAINE

People make subjective judgments about the severity of environmental problems and on future land use relying on certain information, and on their experiences with the problem. This article examines perceptions of the severity of environmental problems, willingness to expend future funds to solve these problems, and future land use for the Department of Energy's Savannah River Site (SRS) in South Carolina as a function of race. The null hypothesis that there are no racial differences in perceptions was tested. Of those interviewed, 23% of the 399 people were black, 75% were white, and 2% identified themselves as other. Blacks were significantly more willing than whites to spend federal funds to solve environmental problems such as cleaning up the SRS and Superfund sites, fixing ozone depletion, and reducing the threats from radon and hightension power lines. There were statistically significant racial differences in preferences for future land use at the SRS, with blacks having a higher preference for using it as a preserve, and whites having a higher preference for a research park, camping, hiking, and hunting. These results indicate that the environmental concerns of the blacks interviewed were equal to or stronger than those of the whites. This is in contrast to much of previously published work that shows that blacks exhibit lower concerns and actions than whites for environmental problems.     

The New Field of Plastics Toxicology - Methods and Results

A large number of medical, dental, and pharmaceutical advancements have been made with the use of new plastic materials for a host of items and devices, ranging from artificial heart valves to specialized packaging systems for the storago and delivery of medications. In the past, many of these devices and items received little attention in regard to potential toxicologic effects upon patients. Since present medical devices are not considered to be “new drugs,” there is great confusion as to the types of preclinical tests which should be performed on these items to ensure the safety of the device. A proper program to evaluate the toxicogenic properties of a material to be used in a medical and paramedical application must, of course, consider the end use of the device. In general, however, test results are needed which will indicate that (1) no toxic ingredient from a plastic will be released to tissue, (2) the released ingredient will not produce an allergic response, and (3) the released agent will not be teratogenic, mutagenic, or carcinogenic. For those materials that are parts of prosthetic devices that will have long-term contact with tissues and blood, consideration must also be given to the interaction of cellular components with the material, thereby altering or degrading the polymer. Other tests and studies will be required for plastic items used for the collection, storage, and administration of drug products, as well as various types of biological products. From the various tests employed, a judgment can then be made as to the benefit-to-risk ratio of the specific device or item.     

Neurotoxicology in the 1990s

During the last ten years, neurotoxicology has entered the mainstream of environmental toxicology as evidenced by numerous national and international conferences, formation of societies related to neurotoxicology, establishment and support of journals devoted to neurotoxicology and reliance of regulatory agencies on neurotoxicological endpoints. Over the last ten years, agreement seems to have been reached concerning the need for and use of neurotoxicological tests for hazard identification. With regard to the future of neurotoxicology, there are a number of important issues that deserve attention, including 1) arriving at a commonly accepted definition of neurotoxicology, 2) the impact of new technology, 3) development of biological markers for neurotoxicology, 4) neurotoxicology of chemical mixtures, 5) relationship between environmental agents and neurodegenerative diseases, 6) use of in vitro procedures in neurotoxicology, 7) risk assessment and 8) development of database for specific neurotoxicants. The last ten years have been productive ones for neurotoxicology. The next ten years should mark a new phase of development marked by significant progress in a number of important areas in environmental toxicology.     

Outline and criteria for evaluating the safety of new chemicals

Risk assessments for chemicals manufactured in large quantities, used by many people, and disposed of broadly into the environment require a systematic process with emphasis on scientific fudgments, specific criteria for decision making, and an overall process for ensuring that human and material resources are used effectively and efficiently. A risk assessment process incorporating these features consists of careful prework in which the physical, chemical, and biological characteristics of the material are organized from known information or predicted from structural considerations as well as information related to the intended manufacture, distribution, use, and disposal. Interrelated programs involving a number of scientific disciplines are then developed for human and for environmental risk assessments. Both of these programs rely on the development of increasingly refined relationships between predicted doses or exposure and biological effects in animal models. Predictive tests for environmental fate and concentrations and for biological effects are selected and conducted progressively. Specific decision criteria based on comparisons of predicted exposures with biological effects data are used to decide when enough testing has been conducted to make a risk assessment. The application of these guidelines to three example chemicals is provided to illustrate the decision-making process.