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On a temporal basis, air has immense capacity for moving a large mass of pollutants. Mammals and birds are exposed to pollutants in air by the inhalation (nose and mouth), cutaneous or ocular routes. Most laboratory studies on air pollutants have been limited to single air pollutants and very little research has been done on the complex mixture of compounds that exist in ambient air. Complex mixtures are further complicated by dynamic chemical reactions that occur after the emissions leave point sources. Exposure parameters are also important in the toxicity of air pollutants. Intermittent exposure of monkeys to ozone increased the adverse pulmonary effects. Superimposing spikes of 0.8 ppm nitrogen dioxide on a baseline of 0.2 ppm, as occurs on a calm winter day, increased the susceptibility of mice to bacteria-induced pneumonia. Sulfur dioxide at concentrations of 5 ppm increased pulmonary resistance by 39%. Sulfuric acid is the predominate acid particle in the atmosphere. Exposure for 1 h to > 200 micrograms sulfuric acid/m3 depressed bronchomucociliary clearance. Concentrations of 100 micrograms/m3 of photochemical products caused headaches and 510 micrograms/m3 produced cough and chest pain. For chemical interactions in dose response, nitrogen dioxide is synergistic with ozone and ammonium sulfate. When all 3 chemicals are used in mixture, the response was 340%. Atmospheric conditions, such as fog, can alter the toxicity of air pollutants. The dose response to a single chemical can be altered by chemical mixtures and pre-existing disease conditions. Understanding these relationships is important for establishing no observable adverse effect levels. Mechanisms for multiple chemical interactions are multifaceted. One chemical may interfere with the metabolism or detoxification of another. Others may interact at cell receptors. To understand the effects of multiple chemical interactions of air pollutants, there is a need for a blend of epidemiological, laboratory and field studies. Studies are expensive. In the rural agricultural settings, the economic and environmental health risks are high. Should field observations and chemical problems be used as "red flags" for action?
We compared the usefulness of t-test and parametric and rank-sum tests in the statistical analysis of significant differences in the so-called "decision tree" for the quantitative data obtained from toxicity studies. The Dunnett's multiple comparison test had lower analytic power than the t-test when one of the groups showed a marked difference in variance. The Dunnett's test was less efficient with the increase in the number of groups. If one group showed a decrease in the number of animals, this test was less efficient than parametric tests, because the rank-sum tests should be chosen. The rank-sum test is required occasionally to attach the asterisks of significant difference to the mean +/- SD even in showing the same mean values. The nonparametric Dunnett's test could not be used for analysis of significant differences when the mean value for the control and treated groups showed big differences. The nonparametric Dunnett's and parametric Scheffé tests were not as efficient as the other parametric tests probably because of the vague evaluation or overlooking the effect of the test substance.
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The evaluation of exposure to polycyclic aromatic hydrocarbons (PAH) should firstly comply with current regulations (D.Lgs. 626/94), that is, identify the compounds and exposed subjects, quantify exposure, adopt preventive measures and health and epidemiological surveillance. Environmental monitoring should take into account the technological cycle and the tasks with higher PAH exposure risk, and the main sources of emissions. In the case of skin contamination, it should be considered the measure of skin PAH by means of sampling or removal techniques; moreover, the determination of urinary hydroxypyrene (1-HP) should be performed. It is mandatory to analyse (Benz[a]) anthracene; Benzo[b]fluroanthene; Benzo[j]fluoranthene; Benzo[k]fluoranthene; Benzo[a]pyrene; Dibenzo[a,h]anthracene, i.e. the PAH marked with the R45-R49 phrase. When 1-HP determination is planned, Pyrene should be added. Biological monitoring has been addressed mainly to hydroxylated metabolites of pyrene and among these 1-HP, the main metabolite of pyrene, although non occupational factors, such as tobacco smoking and consumption of smoked foods are potentially confounding. Urinary mutagenicity tests which are heavily influenced by non occupational factors such as tobacco smoking and diet are not advisable. The determination of DNA and protein adducts is a promising test for evaluation of metabolic active dose but at the moment it is not suitable for routine use in occupational medicine. In order to interpret environmental and biological data, it will be useful to consider appropriate reference values ("limit" "guide", "operative", "maximum admissible") such as 0.1 mg/m3 for total PAH extracted with benzene, 5 micrograms/m3 for the mixture of 15 PAH listed by US NTP, the limits varying from 0.1 to 5 micrograms/m3 for Benzo[a]pyrene, and 2.7-4.4 micrograms/g creat, for 1-HP.
In this paper, the status quo of forensic toxicology in Japan and the West is surveyed and a strategy to address future goals of Japanese forensic toxicology is proposed. Forensic toxicology in the West consists of three main areas--post-mortem forensic toxicology, human-performance forensic toxicology and forensic urine drug testing. In Japan, post-mortem forensic toxicology is practiced in university forensic medicine departments while most of the human-performance forensic toxicology is carried out in police laboratories. However, at least at present, strictly controlled workplace urine drug testing is not being performed, despite the abuse of drugs even by uniformed members of the National Defence Forces and police. For several years, the author has been introducing Western forensic toxicology guidelines and recommendations, translated into Japanese with the help of Western forensic toxicologists, to Japanese forensic toxicologists. Western forensic toxicology practice is at an advanced stage, whereas Japanese practice is in a critical condition and holds many problems awaiting solution, as exemplified by the urine drug testing in police laboratories. There is never any sample left for re-examination by the defence in all cases, though the initial volume of the urine sample available for examination is 30-50 ml. Only one organisation carries out everything from sampling to reporting and, in addition, the parent drug and its metabolites are not quantified. It is clear that the police laboratories do not work within good laboratory practice guidelines, nor do they have quality manuals or standard operating procedures manuals. A basic change in Japanese forensic toxicology practice is now essential. The author strongly recommends that, first of all, Japanese toxicologists should prepare forensic toxicology guidelines based on the Western models. The guidelines would progress the following objectives for forensic toxicology laboratories: 1) to have documented good laboratory practice standards; 2) to have a quality control system including a quality manual and standard operating procedures manual; 3) to have some degree of compulsion to implement quality assurance both through their own internal efforts and by appropriate remedial actions based on the results of an external proficiency testing scheme. For forensic toxicologists, the implications are that they should be: 1) responsible for ensuring that laboratory practices are performed under satisfactory conditions and 2) required to be certified as a forensic toxicology specialist in order to prove their forensic toxicology ability. For their part, governments should: 1) carry out administrative reforms related to forensic toxicology; 2) simplify the procedure for obtaining certified reference materials; 3) introduce a strict workplace urine drug testing programme for government employees, at least for those related to law enforcement. When all of these objectives have been realised, the specific goal will be achieved through which Japanese forensic toxicology is able, in practice, to fulfill its responsibility to society.
Genetic toxicology is the scientific discipline dealing with the effects of chemical, physical and biological agents on the heredity of living organisms. The Internet offers a wide range of online digital resources for the field of Genetic Toxicology. The history of genetic toxicology and electronic data collections are reviewed. Web-based resources at US National Library of Medicine (NLM), including MEDLINE, PUBMED, Gateway, Entrez, and TOXNET, are discussed. Search strategies and Medical Subject Headings (MeSH) are reviewed in the context of genetic toxicology. The TOXNET group of databases are discussed with emphasis on those databases with genetic toxicology content including GENE-TOX, TOXLINE, Hazardous Substances Data Bank, Integrated Risk Information System, and Chemical Carcinogenesis Research Information System. Location of chemical information including chemical structure and linkage to health and regulatory information using CHEMIDPLUS at NLM and other databases is reviewed. Various government agencies have active genetic toxicology research programs or use genetic toxicology data to assist fulfilling the agency's mission. Online resources at the US Food and Drug Administration (FDA), the US Environmental Protection Agency (EPA), the National Institutes of Environmental Health Sciences, and the National Toxicology Program (NTP) are outlined. Much of the genetic toxicology for pharmaceuticals, industrial chemicals and pesticides that is performed in the world is regulatory-driven. Regulatory web resources are presented for the laws mandating testing, guidelines on study design, Good Laboratory Practice (GLP) regulations, and requirements for electronic data collection and reporting. The Internet provides a range of other supporting resources to the field of genetic toxicology. The web links for key professional societies and journals in genetic toxicology are listed. Distance education, educational media resources, and job placement services are also available online in the field of genetic toxicology. As molecular biology and computational tools improve, new areas within genetic toxicology such as structural activity relationship analysis, mutational spectra databases and toxicogenomics, now have resources online as well.
STUDY OBJECTIVE: To determine the number of physicians who have received fellowship training in medical toxicology and to describe fellowship-trained medical toxicologists' perceptions of fellowship training and its career impact. METHODS: All current medical toxicology fellowship directors were contacted by mail for information on who had trained at their program. Subsequently, a written survey was mailed to all current American College of Medical Toxicology members regarding work force and educational issues pertaining to medical toxicology. Fellowship-trained toxicologists were asked about their clinical and research experiences during fellowship, and career impact of toxicology fellowship training. RESULTS: Fellowship directors from 21 programs reported that 147 physicians had completed a toxicology fellowship since 1970. Of the 236 current American College of Medical Toxicology members surveyed, 160 (68%) responded. Ninety-four of the 160 (59%) are fellowship trained. Sixty-four of the 94 (68%) fellowship-trained toxicologists are emergency medicine board certified. About half the respondents believed they did not have enough inpatient and outpatient experiences during fellowship, but poison center time was more than adequate. After fellowship, 91% remain in medical toxicology although 78% spend less than 3/4 time in toxicology-related activities. More than 50% of respondents believed that fellowship training impacted their career by choosing an academic career, developing a toxicology clinical program, and altering clinical responsibilities. CONCLUSIONS: Most fellowship-trained toxicologists only work part-time in medical toxicology, but fellowship training has significant impact on choice of academic career and altering clinical responsibilities. Training concerns include limited bedside experiences, particularly outpatient, and uncertain job prospects.
The toxicology of chemical mixtures will be the toxicology of the 1990s and beyond. While this branch of toxicology most closely reflects the actual human exposure situation, there is yet no standard protocol or consensus methodology for investigating the toxicology of mixtures. Thus, in this emerging science, experimentation is required just to develop a broadly applicable evaluation system. Several examples are discussed to illustrate the different experimental designs and the concepts behind each. These include the health effects studies of Love Canal soil samples, the Lake Ontario Coho salmon, the water samples repurified from secondary sewage in the city of Denver Potable Water Reuse Demonstration Plant, and the National Toxicology Program (NTP) effort on a mixture of 25 frequently detected groundwater contaminants derived from hazardous waste disposal sites. In the last instance, an extensive research program has been ongoing for the last 2 years at the NTP, encompassing general toxicology, immunotoxicology, developmental and reproductive toxicology, biochemical toxicology, myelotoxicology, genetic toxicology, neurobehavioral toxicology, and hepato- and renal toxicology.
Dr. Schwetz is the Acting Deputy Commissioner of the Food and Drug Administration (FDA). He was Director of FDA National Center for Toxicological Research in Jefferson, AR, from 1993 to 1999. A diplomate of the American Board of Toxicology, Dr. Schwetz was acting Director of the Environmental Toxicology Program at the National Institutes of Health National Institute of Environmental Health Sciences (NIEHS) in Research Triangle Park, NC, before coming to the FDA in 1993. He was also Associate Director of the National Toxicology program there. He had been Chief of the Institute Systems Toxicity Branch since 1982. Dr. Schwetz currently serves as Adjunct Professor, Department of Pharmacology and Toxicology/Division of Interdisciplinary Toxicology, at the University of Arkansas for Medical Sciences. He was editor of Fundamental and Applied Toxicology from 1986 to 1992, and serves on the Editorial Advisory Board of Environmental Health Perspectives and Critical Reviews in Toxicology. Dr. Schwetz is an invited member of the Canada Health Protection Branch Science Advisory Board, and an elected member of the National Academy of Sciences Institute of Medicine. He is a member of the Society of Toxicology (SOT) and the National Capitol Area Chapter, SOT; the American Veterinary Medical Association; National Society of Phi Zeta, Honor Society of Veterinary Medicine; Teratology Society; Behavioral Teratology Society; and the Reproductive Toxicology Specialty Section of the SOT. He is past president of the Reproductive Toxicology Specialty Section of the SOT and of the North Carolina and the South Central Chapters of the SOT. In addition to numerous other professional awards during his career, Dr. Schwetz received the U.S. Government 1998 Meritorious Executive Presidential Rank Award.