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The UK Food Standards Agency draft report on variability and uncertainty in toxicology: a response by FRAME.

At the request of the Food Standards Agency, the Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) established a Working Group on Variation and Uncertainty in Toxicology (WG VUT). In April 2006, the WG VUT produced a draft report for public consultation. FRAME made a submission in response to this consultation in July 2006. We commend the WG VUT for its comprehensive account of many of the problems associated with risk assessment, and for making recommendations about the problems that need to be addressed. We were particularly encouraged by the WG VUTs recognition of the need for guidelines on how toxicological studies should be conducted and data analysed. However, we believe that the report has not achieved all of its objectives. It does not adequately consider how modern technologies, experimental design, statistical analysis and species extrapolation can be used in practice to address variability and uncertainty. There is a disproportionate focus on the sources of variability and uncertainty in human data, with relatively little consideration of how variation and uncertainty due to animal tests can be addressed. Furthermore, it is clear that, until the advantages and limitations of all toxicological methods are fully appraised and testing strategies and guidelines are agreed, the scope for improving the existing approaches to risk assessment will be severely limited. Hence, the use of alternative methods for hazard identification and characterisation merit more consideration than they were given in the draft report.

Animals↗

A toxicology databank based on animal safety evaluation studies of pharmaceutical compounds.

Thirteen UK pharmaceutical companies have provided comprehensive toxicological data from repeated-dose animal safety evaluation studies of 74 pharmaceutical compounds. These data comprise a unique toxicology database and this paper describes its establishment including the problems encountered, its current size with over 35 000 data fields, its content and potential value for retrospective analyses. Increasing reliance on animal studies for predicting the safety of medicines in man necessitates a reappraisal of conventional animal testing procedures and better use of the considerable volume of data in the archives of regulatory authorities and pharmaceutical companies. This reappraisal may be achieved by the use of computer-based toxicology databanks.

Animals↗

Analytical toxicology.

1. Major advances in analytical toxicology followed the introduction of spectroscopic and chromatographic techniques in the 1940s and early 1950s and thin layer chromatography remains important together with some spectrophotometric and other tests. However, gas- and high performance-liquid chromatography together with a variety of immunoassay techniques are now widely used. 2. The scope and complexity of forensic and clinical toxicology continues to increase, although the compounds for which emergency analyses are needed to guide therapy are few. Exclusion of the presence of hypnotic drugs can be important in suspected 'brain death' cases. 3. Screening for drugs of abuse has assumed greater importance not only for the management of the habituated patient, but also in 'pre-employment' and 'employment' screening. The detection of illicit drug administration in sport is also an area of increasing importance. 4. In industrial toxicology, the range of compounds for which blood or urine measurements (so called 'biological monitoring') can indicate the degree of exposure is increasing. The monitoring of environmental contaminants (lead, chlorinated pesticides) in biological samples has also proved valuable. 5. In the near future a consensus as to the units of measurement to be used is urgently required and more emphasis will be placed on interpretation, especially as regards possible behavioural effects of drugs or other poisons. Despite many advances in analytical techniques there remains a need for reliable, simple tests to detect poisons for use in smaller hospital and other laboratories.

Doping in Sports↗

Computerized product information system: The Toxicological Index.

The Toxicological Index, a division of the Commission de la Santé et de la Sécurité du Travail, was established in 1980 by the Quebec Government. Its main objective, as a database producer, is to provide health and safety related toxicological information to anyone who is involved in risk management in the workplace. In order to meet this requirement, a fully computerized information system was created. It has allowed us to process, over the past 5 years, 250,000 information inquiries, to register 100,000 contaminants, to exchange information with 3,300 product manufacturers and to provide our users with 6,500 fully reviewed toxicological information profiles. The procedure used to assess the information as well as the choices made to achieve our objective in terms of quantity and quality of the information provided are described.

Chemical Phenomena↗

The impact of toxicology on public health policy and service: an update.

The Division of Toxicology, Agency for Toxic Substances and Disease Registry (ATSDR) has a Congressional mandate to develop toxicological profiles for chemicals of greatest concern at hazardous waste sites. These chemical profiles provide a comprehensive evaluation and interpretation of the health effects, chemical and physical properties, production and use, potential for human exposure, analytical methodologies, and regulations and advisories for those chemicals. In addition, these profiles identify critical gaps in the knowledge base for these chemicals and identify levels of significant human exposure. Health assessors and other public health officials use this information to make critical decisions regarding the potential for adverse health effects at hazardous waste sites and other chemical-release events through such activities as public health assessments, chemical-specific and health-specific consultations, health-guidance-value derivations, database development, and emergency response actions. In a previous paper, we provided an overview of six specific public-health activities conducted by the ATSDR Division of Toxicology and examined how these activities have made unique impacts on public health policy and service. In this paper, we follow up on two of these, ATSDR polychlorinated biphenyls (PCBs) activities and ATSDR mercury activities, and examine their long-term, continually evolving impacts on public health policy and service.

Environmental Pollutants↗

Data quality in predictive toxicology: identification of chemical structures and calculation of chemical properties.

Every technique for toxicity prediction and for the detection of structure-activity relationships relies on the accurate estimation and representation of chemical and toxicologic properties. In this paper we discuss the potential sources of errors associated with the identification of compounds, the representation of their structures, and the calculation of chemical descriptors. It is based on a case study where machine learning techniques were applied to data from noncongeneric compounds and a complex toxicologic end point (carcinogenicity). We propose methods applicable to the routine quality control of large chemical datasets, but our main intention is to raise awareness about this topic and to open a discussion about quality assurance in predictive toxicology. The accuracy and reproducibility of toxicity data will be reported in another paper.

Data Interpretation, Statistical↗

Use of genomics in toxicology and epidemiology: findings and recommendations of a workshop.

The sequencing of the human genome has revolutionized biology and led to an astounding variety of technologies and bioinformatics tools, enabling researchers to study expression of genes, the function of proteins, metabolism, and genetic differences within populations and between individuals. These scientific advances are making an impact in the medical research community and hold great promise for prevention, diagnosis, and treatment of diseases. This developing field also holds great promise for improving the scientific basis for understanding the potential impacts of chemicals on health and the environment. A workshop sponsored by the International Council of Chemical Associations was held to review the state of the science in the application of genomics technologies in toxicology and epidemiology. Further, consideration was given to the ethical, legal, and regulatory issues and their influence on the direction and application of genomics technologies to environmental health research. Four overarching themes emerged from the workshop: Genomics technologies should be used within a framework of toxicology and epidemiology principles and applied in a context that can be used in risk assessment; effective application of these technologies to epidemiology will require suitable biologic samples from large and diverse population groups at the relevant period of exposure; ethical, legal, and social perspectives require involvement of all stakeholder communities; and a unified research agenda for genomics technologies as applied to toxicology, epidemiology, and risk assessment is urgently needed for the regulatory and scientific communities to realize the potential power and benefits of these new technologies.

Animals↗

Application of genomics to toxicology research.

Traditional models of toxicity have relied on dissecting chemical action into pharmacokinetic and pharmacodynamic processes. However, the integration of genomic information with toxicology will enhance our basic understanding of these processes and significantly change the way we apply toxicological information to risk assessment and regulatory problems. In this article, we summarize the application of gene expression information and polymorphism discovery to four areas in toxicology: toxicity testing, cross-species extrapolation, understanding mechanism of action, and susceptibility.

Animals↗

Purpose and guidelines for toxicokinetic studies within the National Toxicology Program.

Toxicokinetic studies undertaken within the National Toxicology Program are intended to aid the design of toxicology and carcinogenicity studies, help interpret the results of toxicology and carcinogenicity studies with respect to the relationship between toxic effects and external exposure, and define the parameters of dose, distribution, metabolism, and elimination that can be used in human risk assessment. Descriptions of two study designs presented here represent the possible extremes in approaches to toxicokinetic studies. The comprehensive approach is geared toward the development of physiology based pharmacokinetic models that relate external exposure to target organ dosimetry and addresses the questions: Is the chemical absorbed? How is the chemical metabolized? Where are the chemical and/or metabolites distributed in the body? What are the elimination rate and route of the chemical? What is the effect of dose on absorption, distribution, metabolism, and elimination? The minimal study design is more limited in scope than the comprehensive design and addresses primarily the issues of absorption, distribution, and elimination of the parent chemical. Study protocols for most chemicals lie somewhere between these two extreme approaches. An increased understanding of the relationships between external exposure, target organ dosimetry, and adverse effects should provide greater confidence in making low-dose extrapolations of human risk. This paper focuses on the collection of data from animal toxicokinetic studies. The construction of comparable models to characterize target organ dosimetry in exposed humans would certainly require the use of human parameter values obtained from human tissue samples and volunteers.

Animals↗

ArrayTrack--supporting toxicogenomic research at the U.S. Food and Drug Administration National Center for Toxicological Research.

The mapping of the human genome and the determination of corresponding gene functions, pathways, and biological mechanisms are driving the emergence of the new research fields of toxicogenomics and systems toxicology. Many technological advances such as microarrays are enabling this paradigm shift that indicates an unprecedented advancement in the methods of understanding the expression of toxicity at the molecular level. At the National Center for Toxicological Research (NCTR) of the U.S. Food and Drug Administration, core facilities for genomic, proteomic, and metabonomic technologies have been established that use standardized experimental procedures to support centerwide toxicogenomic research. Collectively, these facilities are continuously producing an unprecedented volume of data. NCTR plans to develop a toxicoinformatics integrated system (TIS) for the purpose of fully integrating genomic, proteomic, and metabonomic data with the data in public repositories as well as conventional (Italic)in vitro(/Italic) and (Italic)in vivo(/Italic) toxicology data. The TIS will enable data curation in accordance with standard ontology and provide or interface a rich collection of tools for data analysis and knowledge mining. In this article the design, practical issues, and functions of the TIS are discussed through presenting its prototype version, ArrayTrack, for the management and analysis of DNA microarray data. ArrayTrack is logically constructed of three linked components: a) a library (LIB) that mirrors critical data in public databases; b) a database (MicroarrayDB) that stores microarray experiment information that is Minimal Information About a Microarray Experiment (MIAME) compliant; and c) tools (TOOL) that operate on experimental and public data for knowledge discovery. Using ArrayTrack, we can select an analysis method from the TOOL and apply the method to selected microarray data stored in the MicroarrayDB; the analysis results can be linked directly to gene information in the LIB.

Databases, Factual↗

Workgroup report: Review of genomics data based on experience with mock submissions--view of the CDER Pharmacology Toxicology Nonclinical Pharmacogenomics Subcommittee.

Over the past few years, both the U.S. Food and Drug Administration (FDA) and the pharmaceutical industry have recognized the potential importance of pharmacogenomics and toxicogenomics to drug development. To resolve the uncertainties surrounding the use of microarray technology and the presentation of genomics data for regulatory purposes, several pharmaceutical companies and genomics technology providers have provided the FDA with reports of genomics studies that included supporting toxicology data (e.g., serum chemistry, histopathology). These studies were not associated with any active drug application and were exploratory or hypothesis generating in nature. For training purposes, these reports were reviewed by the Nonclinical Pharmacogenomics Subcommittee consisting of the Center for Drug Evaluation and Research pharmacology and toxicology researchers and reviewers. In this article, we describe some of these submissions and report on our assessment of data content, format, and quality control metrics that were useful for evaluating these nonclinical genomics submissions, specifically in relation to the proposed MIAME/MINTox (minimum information about a microarray experiment/minimum information needed for a toxicology experiment) recommendations. These genomics submissions allowed both researchers and regulators to gain experience in the process of reviewing and analyzing toxicogenomics data. The experience will allow development of recommendations for the submission and review of these data as the state of the science evolves.

Animals↗

Infectious diseases of the upper respiratory tract: implications for toxicology studies.

The consequences of adventitious infectious agents upon the interpretation of toxicology studies performed in rats and mice are incompletely understood. Several prevalent murine pathogens cause alterations of the respiratory system that can confuse the assessment of chemically induced airway injury. In some instances the pathogenesis of infection with these agents has been relatively well studied in the lower respiratory tract. However, there are few well-controlled studies that have examined the upper respiratory region, which result in interpretive problems for toxicologic pathologists. The conduct and interpretation of both short-term and chronic rodent bioassays can be compromised by both the clinical and subclinical manifestations of infectious diseases. This paper reviews several important infectious diseases of the upper airway of rats and mice and discusses the potential influence of these conditions on the results of toxicology studies.

Administration, Inhalation↗

Interpretation of analytical toxicology results in life and at postmortem.

Interpretation of analytical toxicology results from live patients is sometimes difficult. Possible factors may be related to: (i) the nature of the poison(s) present; (ii) sample collection, transport and storage; (iii) the analytical methodology used; (iv) the circumstances of exposure; (v) mechanical factors such as trauma or inhalation of stomach contents; and (vi) pharmacological factors such as tolerance or synergy. In some circumstances, detection of a drug or other poison may suffice to prove exposure. At the other extreme, the interpretation of individual measurements may be simplified by regulation. Examples here include whole blood alcohol (ethanol) in regard to driving a motor vehicle and blood lead assays performed to assess occupational exposure. With pharmaceuticals, the plasma or serum concentrations of drugs and metabolites attained during treatment often provide a basis for the interpretation of quantitative measurements. With illicit drugs, comparative information from casework may be all that is available. Postmortem toxicology is an especially complex area since changes in the composition of fluids such as blood depending on the site of collection from the body and the time elapsed since death, amongst other factors, may influence the result obtained. This review presents information to assist in the interpretation of analytical results, especially regarding postmortem toxicology. Collection and analysis of not only peripheral blood, but also other fluids/tissues is usually important in postmortem work. Alcohol, for example, can be either lost from, or produced in, blood especially if there has been significant trauma, hence measurements in urine or vitreous humour are needed to confirm the reliability of a blood result. Measurement of metabolites may also be valuable in individual cases.

Chemistry Techniques, Analytical↗

Information extraction in the life sciences: perspectives for medicinal chemistry, pharmacology and toxicology.

Information extraction approaches have been successfully applied to mine the scientific literature in biology and medicine. So far, the main focus of research and development in this domain was on the recognition and extraction of gene and protein names in the context of molecular biology and genome research and on disease names and other medical terms in the context of clinical research. Similar to biology and medical sciences, medicinal chemistry, pharmacology and toxicology are descriptive sciences. However, information extraction approaches in these disciplines encounter a number of problems that are specific to the fact that these scientific areas are essentially centred at chemical compounds and their structures. In this review, we will give a short overview on general information extraction strategies in the life sciences and we will introduce new approaches to apply information extraction to the domain of pharmacology, medicinal chemistry and toxicology. Finally, we will emphasize on how information extraction approaches will support public and commercial research in medicinal chemistry, pharmacology and toxicology by linking information on chemical structures to biological information.

Biological Science Disciplines↗

Mink as a predictive model in toxicology.

This paper reviewed the biomedical and toxicological database concerning the use of mink as a predictive model of human responses. It is concluded that substantial information exists on the mink genetics, physiology, metabolism, nutritional requirements, and susceptibility to infectious disease; and provides a foundation upon which interspecies extrapolation may be considered. In addition, information on the response of mink to several dozen toxic substances revealed that mink respond in a qualitatively and quantitatively similar manner to other more commonly employed species as well as humans. Our conclusion does not infer that mink should be used routinely in toxicological testing for estimation of human responses. However, it indicates that toxicological data from this species may be a useful complement in risk assessment processes based upon data obtained from traditionally employed models such as rats and dogs.

Animals↗

Behavioral toxicology in risk assessment: problems and research needs.

Behavioral methods are being used with increasing frequency in toxicology to assess the deleterious effects of chemicals to which we are exposed. The impetus for the use of behavioral techniques in risk assessment resulted from the presumption that they were more sensitive than other tests in detecting toxicity. A more logical reason for the use of behavioral tests is the fact that behavior is the functional indicator of the net sensory, motor, and integrative processes occurring in the central and peripheral nervous system. Thus, the functional capacity of the nervous system cannot be determined independent of behavioral analysis. Some of the problems confronting behavioral toxicology are (1) the translation of human subjective complaints into behavioral tests in animals; (2) determining subtle effects on the nervous system in the face of the well-known functional reserve and adaptability of the system; (3) dealing with the variety of statistical problems resulting from the use of multiple tests, multiple measurements using the same test and the (relatively) large variability inherent in some behavioral phenomena; and (4) selecting the proper tests. Three critical research needs in behavioral toxicology as they relate to risk assessment are (1) development and validation of methods, (2) determining subpopulations at greatest risk, and (3) developing a strategy for determining interactions between two or more agents.

Animals↗

The development of a broad-spectrum toxicology screening program in Taiwan.

Our institute serves as a centralized clinical laboratory for municipal and private hospitals in Taipei, a major international metropolis in the Asian region. Two key considerations leading to the development of our toxicology program are: a large number of foreign visitors and local residents returning from overseas trips may bring in chemicals which are less commonly seen in this region; and the lack of readily available assays for a large percentage of commonly used medicines, including prescription and over-the-counter drugs. Our toxicology screening program addresses the needs of both the Emergency Department Drug Screening and Drug of Abuse Screening. In Emergency Department Drug Screening, REMEDi HS is used as the general screening method. In Drug of Abuse Screening, the TDx is used for the initial screening of amphetamine-like substances and opiates, followed by REMEDi HS for the confirmation of positive samples. Emergency Department data collected at our institute over one year (September 1992 to August 1993) identified 57 different drugs in 713 samples. Opiates, narcotics and central stimulants accounted for 24% of the encountered drugs. Presently, there is no extensive reporting of misuse of benzodiazepines in this region. The detection of herbal ingredients like ephedrine and methylephedrine (from the Ma-Huang plant) in patient samples illustrates a large area often overlooked by western toxicology.

Amphetamine↗

Toxicology information and computer sources for the medical practitioner.

This paper addresses the importance of toxicology information in medical practice. It begins by describing the role of clinical toxicology in dealing with health hazards that result from exposure to hazardous chemicals. This is followed by an overview of reference sources of practical value to physicians. Among the types of information considered are books, journals, fact sheets, abstracting/indexing tools, computer services, and organizations. Training resources are also presented. An appendix provides full details on accessing the toxicology resources cited in the body of the paper.

Environmental Health↗