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Toxicological and environmental health information from the National Library of Medicine.

The National Library of Medicine's Toxicology and Environmental Health Information Program is the outgrowth of a 1966 document on "Handling of Toxicological Information," prepared by the Presidents Science Advisory Committee (National Library of Medicine, 1995). The Toxicology and Environmental Health Program is responsible for the creation and deployment of both bibliographic and factual files concerned with toxicology, carcinogenesis, developmental and reproductive effects of chemical substances, toxic chemical releases, and the medical and environmental behavior of chemical substances. The two main computer systems that provide bibliographic and factual data banks are Toxicology Data Network (TOXNET) and ELHILL. A number of the files found in the TOXNET system are built and maintained by other federal agencies such as the National Cancer Institute, the U.S. Environmental Protection Agency, the National Institute for Occupational Safety and Health.

Animals↗
PubMed2000

Knowledge discovery and data mining in toxicology.

Knowledge discovery and data mining tools are gaining increasing importance for the analysis of toxicological databases. This paper gives a survey of algorithms, capable to derive interpretable models from toxicological data, and presents the most important application areas. The majority of techniques in this area were derived from symbolic machine learning, one commercial product was developed especially for toxicological applications. The main application area is presently the detection of structure-activity relationships, very few authors have used these techniques to solve problems in epidemiological and clinical toxicology. Although the discussed algorithms are very flexible and powerful, further research is required to adopt the algorithms to the specific learning problems in this area, to develop improved representations of chemical and biological data and to enhance the interpretability of the derived models for toxicological experts.

Algorithms↗
PubMed2005

Evidence-based toxicology: a comprehensive framework for causation.

This paper identifies deficiencies in some current practices of causation and risk evaluation by toxicologists and formulates an evidence-based solution. The practice of toxicology focuses on adverse health events caused by physical or chemical agents. Some relations between agents and events are identified risks, meaning unwanted events known to occur at some frequency. However, other relations that are only possibilities--not known to occur (and may never be realized)--also are sometimes called risks and are even expressed quantitatively. The seemingly slight differences in connotation among various uses of the word 'risk' conceal deeply philosophic differences in the epistemology of harm. We label as 'nomological possibilities' (not as risks) all predictions of harm that are known not to be physically or logically impossible. Some of these nomological possibilities are known to be causal. We term them 'epistemic'. Epistemic possibilities are risks. The remaining nomological possibilities are called 'uncertainties'. Distinguishing risks (epistemic relationships) from among all nomological possibilities requires knowledge of causation. Causality becomes knowable when scientific experiments demonstrate, in a strong, consistent (repeatable), specific, dose-dependent, coherent, temporal and predictive manner that a change in a stimulus determines an asymmetric, directional change in the effect. Many believe that a similar set of characteristics, popularly called the 'Hill Criteria', make it possible, if knowledge is robust, to infer causation from only observational (nonexperimental) studies, where allocation of test subjects or items is not under the control of the investigator. Until the 1980s, medical decisions about diagnosis, prevention, treatment or harm were often made authoritatively. Rather than employing a rigorous evaluation of causal relationships and applying these criteria to the published knowledge, the field of medicine was dominated by authority-based opinions, expressed by experts (or consensus groups of experts) relying on their education, training, experience, wisdom, prestige, intuition, skill and improvisation. In response, evidence-based medicine (EBM) was developed, to make a conscientious, explicit and judicious use of current best evidence in deciding about the care of individual patients. Now globally embraced, EBM employs a structured, 'transparent' protocol for carrying out a deliberate, objective, unbiased and systematic review of the evidence about a formally framed question. Not only in medicine, but now in dentistry, engineering and other fields that have adapted the methods of EBM, it is the quality of the evidence and the rigor of the analysis through evidence-based logic (EBL), rather than the professional standing of the reviewer, that leads to evidence-based conclusions about what is known. Recent studies have disclosed that toxicologists (individually or in expert groups), not unlike their medical counterparts prior to EBM, show distressing variations in their biases with regard to data selection, data interpretation and data evaluation when performing reviews for causation analyses. Moreover, toxicologists often fail to acknowledge explicitly (particularly in regulatory and policy-making arenas) when shortcomings in the evidence necessitate reliance upon authority-based opinions, rather than evidence-based conclusions (Guzelian PS, Guzelian CP. Authority-based explanation. Science 2004; 303: 1468-69). Accordingly, for answering questions about general and specific causation, we have constructed a framework for evidence-based toxicology (EBT), derived from the accepted principles of EBM and expressed succinctly as three stages, comprising 12 total steps. These are: 1) collecting and evaluating the relevant data (Source, Exposure, Dose, Diagnosis); 2) collecting and evaluating the relevant knowledge (Frame the question, Assemble the relevant (delimited) literature, Assess and critique the literature); and 3) Joining data with knowledge to arrive at a conclusion (General causation--answer to the framed question, Dose-response, Timing, Alternative cause, Coherence). The second of these stages (which amounts to an analysis of general causation), is addressed by an EBM-styled approach (adapted for the infrequent availability of human experimental studies in environmental toxicology). This involves assembling literature (through documented algorithms for database queries), excluding irrelevancies by use of delimiters as filters, and ranking and rating the remaining articles for strength of study design and for quality of execution gauged by application of either a ready-made quality assessment instrument or a custom designed checklist or scale. The results of this systematic review (including a structured review of relevant animal and in vitro studies) are then themselves systematically used to determine which causation criteria are fulfilled. Toxicology is maturing from a derivative science largely devoted to routinized performance and interpretation of safety tests, to a discipline deeply enmeshed in the remarkable advances in biochemistry and molecular biology to better understanding the nature and mechanism of adverse effects caused by chemicals. It is time for toxicologists, like scientists in other fields, to formalize a method for differentiating settled toxicological knowledge of risk from mere nomological possibility, and for communicating their conclusions to other scientists and the public. It is time for EBT.

Animals↗
PubMed2005

Chemical mixtures: considering the evolution of toxicology and chemical assessment.

The assessment of chemical mixtures is a complex topic for toxicologists, regulators, and the public. In this article the linkage between the science of toxicology and the needs of governmental regulatory agencies in the United States is explored through an overview of environmental regulations enacted over the past century and a brief history of modern toxicology. One of the goals of this overview is to encourage both regulators and scientists to consider the benefits and limitations of this science-regulatory relationship as they tackle existing issues such as chemical mixtures. It is clear that a) over the past 100 years chemical regulation and toxicologic research, have in large part, shared a common emphasis on characterization and regulation of individual chemicals. But chemical mixtures have been, and continue to be, evaluated at hazardous waste sites around the United States. For this reason the current U.S. Environmental Protection Agency guidelines for chemical mixtures assessment are also reviewed. These guidelines highlight the current practice of mixtures assessment, which relies primarily on the existing single-chemical database. It is also clear that b) the science and assessment of chemical mixtures are moving forward through the combined efforts of regulatory agencies and scientists from a broad range of disciplines, including toxicology. Because toxicology is at this exciting crossroads, particular attention should be paid to the forces (e.g., public demands, regulatory needs, funding, academic interests) that both promote and limit the growth of this expanding discipline.

Environmental Exposure↗
PubMed1985

Use of selected toxicology information resources in assessing relationships between chemical structure and biological activity.

This paper addresses the subject of the use of selected toxicology information resources in assessing relationships between chemical structure and specific biological end points. To assist the researcher in how to access the primary literature of genetic toxicology, teratogenesis, and carcinogenesis, three specific specialized information centers are discussed--Environmental Mutagen Information Center, Environmental Teratology Information Center, and Environmental Carcinogenesis Information Center. Also included are descriptions of information resources that contain evaluated (peer-reviewed) biological research results. The U.S. Environmental Protection Agency Genetic Toxicology Program, the International Agency for Research on Cancer Monographs, and the Toxicology Data Bank are the best sources currently available to obtain peer-reviewed results for compounds tested for genotoxicity, carcinogenicity, and other toxicological end points. The value of published information lies in its use. It has become evident that most information cannot be accepted at face value for interpretation and analysis when subjected to stringent quality evaluation criteria. This deficit can be corrected by rigid editorship and the cognizance of authors. Increased interest in alternative methods to in vivo animal testing will be exemplified by use of short-term bioassays and in structure-activity relationship studies. With respect to this latter area, it must be remembered that mechanically (computer generated) derived data cannot substitute, at least at this stage, for data obtained from actual animal testing. The future of structure-activity relationship studies will rest only in their use as a predictive tool.

Carcinogens, Environmental↗
PubMed1993

Toxicological approaches to complex mixtures.

This paper reviews the role of toxicological studies in understanding the health effects of environmental exposures to mixtures. The approach taken is to review mixtures that have received the greatest emphasis from toxicology; major mixtures research programs; the toxicologist's view of mixtures and approaches to their study; and the complementary roles of toxicological, clinical, and epidemiological studies. Studies of tobacco smoke, engine exhaust, combustion products, and air pollutants comprise most of the past research on mixtures. Because of their great experimental control over subjects, exposures, and endpoints, toxicologists tend to consider a wider range of toxic interactions among mixture components and sequential exposures than is practical for human studies. The three fundamental experimental approaches used by toxicologists are integrative (studying the mixture as a whole), dissective (dissecting a mixture to determine causative constituents), and synthetic (studying interactions between agents in simple combinations). Toxicology provides information on potential hazards, mechanisms by which mixture constituents interact to cause effects, and exposure dose-effect relationships; but extrapolation from laboratory data to quantitative human health risks is problematic. Toxicological, clinical, and epidemiological approaches are complementary but are seldom coordinated. Fostering synergistic interactions among the disciplines in studying the risks from mixtures could be advantageous.

Air Pollutants↗
PubMed1996

Information technologies for clinical toxicology in Russia.

OBJECTIVE: To describe Poison Information in Russia. RESULTS: The Moscow Toxicology Information and Advisory Center was created in 1993 as an institution of the Russian Federation Ministry of Health and Medical Industry. The Toxicology Information and Advisory Center is the first in a network of over 20 toxicology information centers to be created in different regions of Russia by 1998. At present the Toxicology Information and Advisory Center serves over 20 million people in the Moscow region with episodic inquiries from other areas. A prototype national bank of clinical and toxicological data on acute chemical poisoning and an information retrieval system POISON have been created. Work is underway to create computerized systems for data analysis of telephone inquiries on diagnosis and treatment protocols of acute poisoning.

Computer Communication Networks↗
PubMed2001

[The importance of standardised cell culture methods for the routine toxicology in pharmaceutical companies].

The establishment and the use of standardised cell cultures build the basis for toxicological investigations and guarantees the comparison over years. The requirement for these investigations in vitro are mainly primary cell cultures from the target organs. The cell cultures should keep, also under long term culture conditions, the organ differentiation. This will be supported by new developments in the fields of cell culture media, supplements and coating material of the cell culture dishes. Routinely, cells from toxicologically important organs like liver, kidney and nervous system were used in vitro. However, mechanistic investigations of toxicological findings in vivo made the use of cell systems from other organs like cartilage, bone, skeletal and heart muscle cells, testis eg necessary. All cell culture systems were established and standardised to allow repeated tests under the same conditions. The determination of characteristic proteins or enzymes of the related organ will demonstrate the organ like quality of the cell cultures. The central question of toxicology is the risk assessment. Here, the in vitro toxicology will provide important information by a comparison between human and animal cell cultures under the same conditions.

Animal Testing Alternatives↗
PubMed2003

Characteristics and toxicological processing of postmortem pilot specimens* from fatal civil aviation accidents.

INTRODUCTION: Autopsied biosamples from civil aviation accident pilot fatalities are submitted to the Civil Aerospace Medical Institute (CAMI) for toxicological evaluation. However, such evaluation is dependent on types and amounts of submitted samples, and obtaining suitable samples is governed by the nature of the accident. Characteristics of those samples and associated toxicological processing have not been well documented in the literature. METHOD: Therefore, the CAMI Toxicology Database was searched for these aspects. RESULTS: CAMI received samples from the pilot fatalities (CAMI cases) of approximately 80% of the 1990-2000 aviation accidents reported by the National Transportation Safety Board. Accidents and cases during June-September were higher than the other months, and more than half of the received cases had multiple samples in sufficient amounts. For example, out of 1891 cases processed for the 1996-2000 accidents, 1211 had at least adequate amounts of blood, urine, and/or vitreous humor; 324 had inadequate amounts of blood and urine; and 356 had no blood or urine. Muscle, liver, lung, and/or kidney samples were submitted in 90% of the cases, while cerebrospinal fluids were submitted in only 8% of the cases. The toxicologically preferred samples, blood and urine, were available in 78% and 56% of the 1891 cases, respectively. Out of 51 cases containing only one sample type, 46 had muscle and the remaining 5 had other sample types. Samples were primarily analyzed for combustion gases, alcohol/volatiles, and drugs. Generally, the presence of analytes is demonstrated in at least two different sample types by using two different analytical techniques for reporting a particular case as "positive." An effective quality-assurance/quality-control is maintained throughout the process. CONCLUSION: In the majority of the aviation accidents, sufficient amounts and types of biological samples were submitted for toxicological evaluation.

Accidents, Aviation↗
PubMed1990

NTP Toxicology and Carcinogenesis Studies of 3,3'-Dimethoxybenzidine Dihydrochloride (CAS No. 20325-40-0) in F344/N Rats (Drinking Water Studies).

3,3'-Dimethoxybenzidine dihydrochloride is an off-white powder with a melting point of 274 degrees C. 3,3'-Dimethoxybenzidine is used principally as an intermediate in the production of commercial bisazobiphenyl dyes for coloring textiles, paper, plastic, rubber, and leather. In the synthesis of the bisazobiphenyl dyes, the amine groups of 3,3'-dimethoxybenzidine are chemically linked with other aromatic amines. A small quantity of 3,3'-dimethoxybenzidine is also used as an intermediate in the production of o-dianisidine diisocyanate, which is used in isocyanate-based adhesive systems and as a component of polyurethane elastomers. 3,3'-Dimethoxybenzidine dihydrochloride was evaluated in toxicity and carcinogenicity studies as part of the National Toxicology Program's Benzidine Dye Initiative. This Initiative was designed to evaluate the representative benzidine congeners and benzidine congener-derived and benzidine-derived dyes. 3,3'-Dimethoxybenzidine dihydrochloride was nominated for study because of the potential for human exposure during production of bisazobiphenyl dyes and because benzidine, a structurally related chemical, is a known human carcinogen. NTP Toxicology and Carcinogenesis studies were conducted by administering 3,3'-dimethoxybenzidine dihydrochloride (greater than 97.5% pure) in drinking water to groups of F344/N rats of each sex for 14 days, 13 weeks, 9 months, or 21-months. The 21-month studies were intended to last 24 months but were terminated early because of rapidly declining survival due to neoplasia. Studies were performed only in rats because similar studies are being performed in mice at the National Center for Toxicology Research. Genetic toxicology studies were conducted with Salmonella typhimurium, Chinese hamster over (CHO) cells, and Drosophila melanogaster. Fourteen-Day Studies: All rats receiving drinking water concentrations up to 4,500 ppm lived to the end of the studies. Rats that received water containing 4,500 ppm 3,3'-dimethoxybenzidine dihydrochloride lost weight. Water consumption decreased with increasing concentration of chemical and at 4,500 ppm was less than one-fourth that by the controls. Lymphoid depletion of the thymus in males and hypocellularity of the bone marrow in males and females were seen at the 4,500-ppm concentration, but not at the next lower concentration or in controls. Thirteen-Week Studies: All rats receiving concentrations up to 2,500 ppm lived to the end of the studies. Final mean body weights of rats given drinking water containing 1,250 or 2,500 ppm 3,3'-dimethoxybenzidine dihydrochloride were 5%-20% lower than those of controls. Water consumption at these concentrations was 40%-60% that consumed by controls. Compound-related effects in rats given water containing 2,500 ppm 3,3'-dimethoxybenzidine dihydrochloride included a mind exacerbation of naturally occurring nephropathy and the presence of a yellow-brown pigment (lipofuscin) in the cytoplasm of thyroid follicular cells. Serum triiodothyronine (T3) and thyroxin (T4) concentrations in females receiving 330 ppm or more and T4 concentrations in males receiving 170 ppm or more were significantly lower than in controls. Thyrotropin (TSH) concentrations were comparable in controls and exposed rats. Based on the chemical-related nephropathy and reductions in water consumption and body weight gain observed in the 13-week studies, doses for the long-term studies in male and female rats were 0 or 330 ppm 3,3'-dimethoxybenzidine dihydrochloride in drinking water administered for 9 months and 0, 80, 170, or 330 ppm administered for 21 months. Nine-Month Studies: Ten rats of each sex in control and 330-ppm groups were evaluated after 9 months. Significant decreases in T3 and T4 concentrations were seen in exposed male and female rats. Other lesions seen in exposed rats included foci of alteration in the liver, a carcinoma of the preputial gland in one male, a carcinoma of the clitoral gland in one female, and carcinoma of the Zymbal gland in two males. Body Weights and Survival in the Twenty-One-Month Studies: The average amount of 3,3'-dimethoxybenzidine dihydrochloride consumed per day was approximately 6, 12, or 21 mg/kg for low, mid, or high dose male rats and 7, 14, or 23 mg/kg for low, mid, or high dose female rats. Mean body weights of male and female rats began to decrease relative to those of controls after about 1 year of exposure at 170 or 330 ppm and were 6%-22% lower for males and 7%-17% lower for females. Survival of rats exposed to 3,3'-dimethoxybenzidine dihydrochloride was reduced because animals were dying with neoplasms or being killed in a moribund condition (survival at 21 months--male: control, 44/60, 73%; low dose, 8/45, 18%; mid dose, 0/75; high dose, 0/60; female: 45/60, 75%; 15/45, 33%; 6/75, 8%; 0/60). Because of these early compound-related deaths, the studies were terminated at 21 months. Nonneoplastic and Neoplastic Effects in the Twenty-One-Month Studies: Increased incidences of several nonneoplastic lesions were observed in exposed rats, including hematopoietic cell proliferation in the spleen and cystic and centrilobular degeneration and necrosis of the liver. Neoplasms attributed to 3,3'-dimethoxybenzidine dihydrochloride exposure were observed in rats at many tissue sites, including the skin, Zymbal gland, preputial and clitoral glands, oral cavity, small and large intestines, liver, brain, mesothelium, mammary gland, and uterus/cervix. The incidences of these neoplasms in male and female rats are given in the abstract summary table (see page 5 of the Technical Report). Genetic Toxicology: 3,3'-Dimethoxybenzidine was mutagenic in S. typhimurium strain TA100 with exogenous metabolic activation and in strain TA98 without activation; a weakly positive response was observed in strain TA1535 with metabolic activation. 3,3'-Dimethoxybenzidine induced sister chromatid exchanges and chromosomal aberrations in CHO cells with and without exogenous metabolic activation. 3,3'-Dimethoxybenzidine did not induce sex-linked recessive lethal mutations in adult male D. melanogaster exposed via feeding or injection. Conclusions: Under the conditions of these 21-month drinking water studies, there was clear evidence of carcinogenic activity of 3,3'-dimethoxybenzidine dihydrochloride for male F344/N rats, as indicated by benign and malignant neoplasms of the skin, Zymbal gland, preputial gland, oral cavity, intestine, liver, and mesothelium. Increased incidences of astrocytomas of the brain may have been related to chemical administration. There was clear evidence of carcinogenic activity of 3,3'-dimethoxybenzidine dihydrochloride for female F344/N rats, as indicated by benign and malignant neoplasms of the Zymbal gland, clitoral gland, and mammary gland. Increases in neoplasms of the skin, oral cavity, large intestine, liver, and uterus/cervix were also considered to be related to chemical administration of 3,3'-dimethoxybenzidine dihydrochloride. Synonyms: o-dianisidine dihydrochloride; 3,3'-dimethoxy-1,1-biphenyl)-4,4'-diamine dihydrochloride; 3,3'-dimethoxy-4,4'-diaminobiphenyl dihydrochloride

Journal Article↗
PubMed1990

NTP Toxicology and Carcinogenesis Studies of Toluene (CAS No.108-88-3) in F344/N Rats and B6C3F1 Mice (Inhalation Studies).

Toluene is used to back-blend gasoline, as a chemical intermediate, and as a solvent; 920 million gallons were produced in the United States in 1988. Toxicology studies were conducted by administering toluene (greater than 99% pure) in corn oil by gavage to groups of F344/N rats and B6C3F1 mice of each sex for 13 weeks or by whole-body inhalation exposure for 14 or 15 weeks. NTP Toxicology and Carcinogenesis studies were conducted by whole-body inhalation exposure of F344/N rats and B6C3F1 mice of each sex for 15 months or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, mouse L5178Y lymphoma cells, and Chinese hamster ovary cells. Thirteen-Week Gavage Studies: All rats that received the top dose of 5,000 mg/kg died during the first week, and 8/10 male rats that received 2,500 mg/kg died early. The final mean body weight of male rats that received 2,500 mg/kg was 19% lower than that of vehicle controls. Relative liver, kidney, and heart (female only) weights for rats that received the higher doses were greater than those for vehicle controls. Necrosis of the brain and hemorrhage of the urinary bladder were seen at increased incidences in dosed rats. All mice that received the top dose of 5,000 mg/kg died during the first week, and 40% of those that received 2,500 mg/kg died before the end of the 13-week gavage studies. The final mean body weight of males at 2,500 mg/kg was 16% lower than that of vehicle controls. At the higher doses, relative liver weights were increased for mice. Fifteen-Week and Fourteen-Week Inhalation Studies: Eight of 10 male rats exposed at the top exposure concentration of 3,000 ppm died during week 2. Final mean body weights of rats exposed at concentrations of 2,500 or 3,000 ppm were 14%-25% lower than that of controls. As in the gavage studies, the relative liver, kidney, and heart weights for rats exposed at the top two concentrations were increased compared with those for controls. No compound-related effects were seen on sperm; no adverse effects on the estrous cycle were observed. Five of 10 male mice and all female mice exposed at 3,000 ppm and 70% of female mice at 2,500 ppm died during the first 2 weeks. Final mean body weights of all exposed groups were 7%-13% lower than those of controls. Relative liver weights for mice exposed at 625 ppm or higher, relative lung weights for mice exposed at 1,250 ppm or higher, and relative kidney weights for female mice exposed at 1,250 ppm or higher were greater than those for controls. Centrilobular hypertrophy of the liver was observed in all male mice exposed at 2,500 ppm and 70% of male mice exposed at 3,000 ppm. No effects on sperm or the estrous cycle were observed. Fifteen-Month and Two-Year Inhalation Studies: Long-term studies were conducted by exposing groups of 60 rats of each sex to 0, 600, or 1,200 ppm toluene by inhalation, 6.5 hours per day, 5 days per week. Groups of 60 mice of each sex were exposed at 0, 120, 600, or 1,200 ppm on the same schedule. Ten animals per group (except male mice) were removed for toxicologic evaluation after being exposed for 15 months. All other animals were exposed to toluene for 103 weeks. In the 15-month inhalation studies, the incidences and severity of nonneoplastic lesions of the nasal cavity (degeneration of olfactory and respiratory epithelium and goblet cell hyperplasia) were increased in exposed rats. Minimal hyperplasia of the bronchial epithelium was seen in 4/10 female mice at 1,200 ppm. The severity of nephropathy was slightly increased in exposed female rats. No chemical-induced neoplasms were observed. Body Weight and Survival in the Two-Year Studies: Mean body weights of rats and mice were generally similar (yearly averages within 5%) among groups throughout the 2-year studies. No significant differences in survival were observed among rats or mice of either sex, although survival in all groups of male mice was lower than usual (male rats: control, 30/50; 600 ppm, 28/50; 1,200 ppm, 22/50; female rats: 33/50; 35/50; 30/50; male mice: control, 17/60; 120 ppm, 22/50; female rats: 33/50; 35/50; 30/50; male mice: control, 17/60; 120 ppm, 22/60; 600 ppm, 16/60; 1,200 ppm, 19/60; female mice: 30/50; 33/50; 24/50; 32/50). Scrotal, preputial, and penile lesions observed in male mice were associated with many of the early deaths and with animals killed in a moribund condition. Nonneoplastic and Neoplastic Effects in the Two-Year Studies: Nephropathy was seen in almost all rats, and the severity was somewhat increased in exposed rats. A rare renal tubular cell carcinoma in a female rat and an equally uncommon sarcoma of the kidney in another female rat were seen in the 1,200-ppm exposure group. Erosion of the olfactory epithelium and degeneration of the respiratory epithelium were increased in exposed rats. Inflammation of the nasal mucosa and metaplasia of the olfactory epithelium were increased in exposed female rats. A rare squamous cell carcinoma of the nasal mucosa was seen in one female rat at 1,200 ppm. A squamous cell papilloma of the forestomach was observed in one female rat at 1,200 ppm, and a squamous cell carcinoma was observed in a second female rat at 1,200 ppm. No chemically related neoplasms were found in male rats, and the one nasal, two kidney, and two forestomach neoplasms observed in female rats were considered not to be associated with inhalation exposed to toluene. For mice, no biologically important increases were observed for any nonneoplastic or neoplastic lesions. Genetic Toxicology: Toluene did not induce gene mutations in S. typhimurium strain TA98, TA100, TA1535, or TA1537 with or without exogenous metabolic activation. In the mouse lymphoma assay, toluene gave an equivocal response with and without exogenous metabolic activation. Toluene did not induce sister chromatid exchanges or chromosomal aberrations in Chinese hamster ovary cells in the presence or absence of exogenous metabolic activation. Conclusions: Under the conditions of these 2-year inhalation studies, there was no evidence of carcinogenic activity for male or female F344/N rats exposed to toluene at concentrations of 600 or 1,200 ppm. There was no evidence of carcinogenic activity for male or female B6C3F1 mice exposed by inhalation to toluene at concentrations of 120, 600, or 1,200 ppm for 2 years. Synonyms: monomethylbenzene; methylbenzene; toluol; phenylmethane; tolueen (Dutch); toluen (Czech), tolueno (Spanish); toluolo (Italian) Trade Name: Methacide

Journal Article↗
PubMed2003

Toxicology of suicide: touchstone for suicide prevention?

BACKGROUND: Systematic studies of consecutive suicides show that risk for suicide concentrates heavily in people with psychiatric illness, particularly depressive disorders and substance abuse. It is generally assumed that suicide is preventable although there is currently no conclusive evidence for efficacy of any preventive action, including use of psychotropic prescription medications. The low base-rate of suicide and ethical concerns of studying suicidal people in controlled trials of medications or psychotherapy are the two most important obstacles for progress in suicide research. No prevention suicide program currently includes routine toxicological monitoring of suicide or other violent death. The use of toxicological monitoring in suicide was examined in this study. MATERIAL/METHODS: Review of the literature on toxicological studies of suicide, in particular of a study done in consecutive suicides in Mobile County, Alabama, between 1990-1998. RESULTS: Toxicological studies in suicides support that there is undertreatment of depressive disorders in people who are at risk for suicide and that substance abuse is an important risk factor. Higher detection rates of antidepressants in recent suicide samples may indicate higher treatment rates of depression. CONCLUSIONS: Surveillance of psychoactive substances among suicides may be a novel and practical way to assess efficacy of selected medical interventions aimed at reducing the number of suicides. Use of toxicological monitoring in suicide should be explored in future studies.

Age Factors↗
PubMed1986

NTP Toxicology and Carcinogenesis Studies of Dimethylvinyl Chloride (1-Chloro-2-Methylpropene) (CAS No. 513-37-1) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

Dimethylvinyl chloride is a clear colorless liquid, which, because of its volatility and flammability at room temperature, is a significant fire hazard. It has a boiling point of 68.1 degrees C (155 degrees F) and a density at 20 degrees C of 0.919 g/ml. Dimethylvinyl chloride is a byproduct in the production of 3-chloro-2-methylpropene by the chlorination of isobutene. It is not known to be produced in the United States for other than laboratory purposes. This chemical was nominated for toxicologic studies because of its reported presence in ambient air in the Baltimore area and was selected for toxicologic characterization because of its structural similarity to the known animal and human carcinogen, vinyl chloride monomer. Toxicology and carcinogenesis studies of dimethylvinyl chloride (96%-98% pure), a structural analog of vinyl chloride monomer, a known human carcinogen, by administered dimethylvinyl chloride in corn oil by gavage to groups of 50 male and 50 female F344/N rats and B6C3F1 mice at doses of 0, 100, or 200 mg/kg body weight 5 days per week for 102 or 103 weeks. The selection of these doses was based on results of 13-week studies, which included depression of body weight at doses of 500 mg/kg or above in rats as well as histopathologic changes intestinal epithelium, bone marrow, hepatocytes, and the testes at doses of 250 mg/kg and above; doses in mice were selected on the basis of histopathologic changes in lymphopoietic cells, liver, pancreatic islets, ovary, testis, and spleen, with changes being most prominent at doses of 500 mg/kg and above. In the 2-year studies, body weights of rats and mice given 100 mg/kg were comparable to those of the vehicle controls except for the last few weeks in mice when body weights were markedly lower than those for the vehicle controls. At 200 mg/kg, the mean body weights of rats and mice were progressively decreased relative to those of vehicle controls, with the significant departure from vehicle controls occurring somewhat earlier in males than in females. Survival of vehicle control rats and mice was comparable to historical values; however, survival of dosed male and female rats was significantly lower than that of vehicle controls, with the incidence of mortality being more severe at the high dose than at the low dose. There were no survivors in the high dose group of male rats after week 85 or in the high dose group of female rats after week 97. Survival was significantly lower among dosed male and female mice compared with vehicle controls. In the absence of toxicological findings that would explain the early deaths, it is assumed that the high incidence of tumors and chemical-related toxicity contributed to the decreased survival of dosed rats and mice. In rats, the severity and incidence of nonneoplastic lesions were minimal; these lesions included necrosis of the duodenum and epithelial hyperplasia at the sites of tumor formation--the nasal cavity, esophagus, and forestomach. In mice, the severity of nonneoplastic lesions was also minimal; the lesions included necrosis of the liver, bone marrow granulocytic hyperplasia, and inflammation of the nasal cavity (small number, females only.) Several types of neoplastic lesions occurred with significantly increased incidences in dosed animals as shown in the following table (see page 11 of Technical Report). Among rats, these lesions included malignant epithelial tumors of the nasal cavity and squamous cell tumors of the oral cavity, esophagus, and forestomach in males and females. The increased number of fibroadenomas of the mammary gland in female rats may have been related to dimethylvinyl chloride administration. The lack of a clear dose-response relationship for certain tumors in rats is considered to be related to the increased number of early deaths observed in the high dose groups. Among dosed mice, there were significantly increased incidences of squamous cell carcinomas of the forestomach (both sexes), squamous cell papillomas of the forestomach (males), and squamous cell carcinomas of the preputial gla preputial gland (males). The increased incidence of papillary adenomas of the harderian gland and alveolar/bronchiolar adenomas or carcinomas in female mice may have been related to administration of dimethylvinyl chloride. Limited metabolism studies of 14C-labeled dimethylvinyl chloride were conducted in male F344/N rats and B6C3F1 mice. Single doses of 150 mg/kg were administered to rats for 1, 2, or 4 consecutive days. About 25% of the administered doses was exhaled as carbon dioxide; this amount was independent of the number of doses administered. Another 25%-35% of the administered dose was exhaled; 96% of this parent was material. Approximately 35% and 6% were excreted in the urine and feces, respectively. The elimination half-life of radioactive label was 3-4 days for the liver and kidney, the two organs containing the greatest amounts of the administered dose. In mice, a much smaller fraction of the dose was exhaled and a larger proportion was excreted in urine compared with rats. Dimethylvinyl chloride was not mutagenic in four strains ofSalmonella typhimurium with or without metabolic activation, but it was mutagenic in the mouse lymphoma L5178Y/TK± assay in the absence of metabolic activation. Sister-chromatid exchanges were induced in Chinese hamster ovary cells with and without metabolic activation, but there was no increase in chromosomal aberrations. When fed to Drosophila, dimethylvinyl chloride induced significant increases in the frequencies of both sex-linked recessive lethal mutations and reciprocal translocations. Studies of the immunotoxicity of dimethylvinyl chloride were conducted in which female B6C3F1 mice received daily oral doses of 0, 50, 100, 200, or 400 mg dimethylvinyl chloride per kilogram body weight. Compound-related increases in susceptibility to bacterial infection and decreases in macrophage cytostasis were observed at all doses. At the highest dose, the decreased resistance to bacterial and viral challenge could be related to alterations in specific immune function. However, the increased mortality in rats and mice in the 2-year studies was not relatable to infectious processes. An audit of the experimental data was conducted for these2-year toxicology and carcinogenesis studies on dimethylvinyl chloride. No data discrepancies were found that influenced the final interpretations. Under the conditions of these 2-year gavage studies, there was clear evidence of carcinogenicity of dimethylvinyl chloride for both sexes of F344/N rats and B6C3F1 mice. This was based on increased incidences of neoplasms of the nasal cavity, oral cavity, esophagus, and forestomach of male and female F344/N rats. B6C3F1 mice showed increased incidences of squamous cell neoplasms of the forestomach in males and females and squamous cell carcinomas of the preputial gland in males. Synonym: 1-chloro-2-methylpropene

Journal Article↗
PubMed1990

Cost analysis in the toxicology laboratory.

The process of determining laboratory sectional and departmental costs and test costs for instrument-generated and manually generated reportable results for toxicology laboratories has been outlined in this article. It is hoped that the basic principles outlined in the preceding text will clarify and elucidate one of the most important areas needed for laboratory fiscal integrity and its survival in these difficult times for health care providers. The following general principles derived from this article are helpful aids for managers of toxicology laboratories. 1. To manage a cost-effective, efficient toxicology laboratory, several factors must be considered: the laboratory's instrument configuration, test turnaround time needs, the test menu offered, the analytic methods used, the cost of labor based on time expended and the experience and educational level of the staff, and logistics that determine specimen delivery time and costs. 2. There is a wide variation in costs for toxicologic methods, which requires that an analysis of capital (equipment) purchase and operational (test performance) costs be performed to avoid waste, purchase wisely, and determine which tests consume the majority of the laboratory's resources. 3. Toxicologic analysis is composed of many complex steps. Each step must be individually cost-accounted. Screening test results must be confirmed, and the cost for both steps must be included in the cost per reportable result. 4. Total costs will vary in the same laboratory and between laboratories based on differences in salaries paid to technical staff, differences in reagent/supply costs, the number of technical staff needed to operate the analyzer or perform the method, and the inefficient use of highly paid staff to operate the analyzer or perform the method. 5. Since direct test costs vary directly with the type and number of analyzers or methods and are dependent on the operational mode designed by the manufacturer, laboratory managers should construct an actual test-cost data base for instrument or method in use to accurately compare costs using the "bottom-up" approach. 6. Laboratory expenses can be examined from three perspectives: total laboratory, laboratory section, and subsection workstation. The objective is to track all laboratory expenses through each of these levels. 7. In the final analysis, a portion of total laboratory expenses must be allocated to each unit of laboratory output--the billable procedure or, in laboratories where tests are not billed, the tests produced.(ABSTRACT TRUNCATED AT 400 WORDS)

Costs and Cost Analysis↗
PubMed1988

Joint Toxicology Network at the Latin American Regional Level.

The Environmental Health Program of the Pan American Health Organization has established goals to be able to comply with the resolutions of the Board of Directors and the Executive Committee. As an integral part of the Environmental Health Program, the Pan American Center for Human Ecology and Health (ECO) must contribute to the achievement of these goals. Generally speaking, there is a scarcity of toxicology professionals in the Region of the Americas. In order to ameliorate this situation, it is suggested that activities in the areas of training professionals, conducting research, dissemination of information, and publishing of educational materials be undertaken. It is proposed that the "Joint Toxicology Network at the Regional Level" be created. The objectives of such a network would be the promotion and encouragement of activities in the area of toxicology; assistance to countries in identifying their needs; encouragement of information exchange, publication and training in toxicology; and support of the Toxicology Information Centers. In order to achieve the Network objectives, it is suggested that activities be undertaken by the national groups belonging to the network.

Environmental Health↗
PubMed1979

Baccalaureate program in toxicology.

A meaningful baccalaureate program in toxicology will help meet the critical manpower needs in this field. A strong undergraduate program in toxicology also will benefit the science of toxicology by: (1) Relieving PhD toxicologists from more routine tasks they perform: (2) informing bright young scientists, earlier in their careers, about potential careers in toxicology; and (3) developing wider public acceptance for toxicology and safety assessment.

Pennsylvania↗
PubMed1979

[Contemporary problems of industrial toxicology].

The author presents the present -- day position and developmental trends of industrial toxicology studies, relating this specialty to other hygiene branches, especially to natural environment protection. Disproportions in the development of this line of studies was indicated, as opposed to the progress in technique and technology. These disproportions are most evident when we compare the number of chemicals for whose some data determining their biological effects have been collected, with over 4 mln. chemical compounds used in our economy. The main general problems to be solved in the nearest future are: scientific and technical information and establishment, at an international level, of basic definitions, criteria of toxicity evaluation and occupational risk, related classification and bases constituting a starting point for establishing the hygienic standards (MAC). In addition, current orientation of studies in narrower specialties within industrial toxicology was discussed, i.e. experimental toxicology, chemical air analysis, toxicological biochemistry, chemical substances metabolism in organism, pathology of acute and chronic intoxications. The development of new narrow specialties and new problems was pointed out, in view of their perspective significance for the health protection of workers occupationally exposed to chemicals. Among those problems are: remote effects of exposure to chemicals, especially the problem of industiral carcinogenesis, combined effects of poisons, and so called behavioral toxicology. It was noted that the present knowledge of carcinogenic effects of chemicals permits to gradually set up efficient preventive measures, conditioned by implementation of systems of occupational risk control and the control of health effects of exposure.

Carcinogens↗
PubMed1999

Toxicological analysis in agitated patients.

OBJECTIVE: To assess the toxicological etiologies in agitated patients and to evaluate their initial clinical diagnosis in the light of toxicological results analysis. DESIGN: Prospective clinical study. SETTING: Emergency Department (ED) in a 2,650-bed University Hospital. PATIENTS: Fifty-eight consecutively enrolled patients admitted to the ED in agitated states over a 6-month period. MEASUREMENTS AND RESULTS: All patients underwent laboratory tests including blood glucose, ethanol and serum drug screening. Toxicology tests were conducted by fluorescence polarization immunoassay and confirmed by high performance liquid chromatography/diode array detector and gas chromatography-mass spectrometry. The physician's initial diagnosis was evaluated in the light of toxicological analysis results. Serum toxicological analysis revealed that 50/58 patients were under the influence of alcohol and/or a drug. Benzodiazepines (22/58), selective serotonin reuptake inhibitors (5/58) and opiates (4/58) were the most frequently observed. The initial clinical diagnosis was alcohol intoxication in 39 patients, although 1 patient was not under the influence of alcohol and 16 also had benzodiazepine in their sera. Moreover, the diagnosis of serotonin syndrome was overlooked in two patients. CONCLUSION: Most agitated patients were under the influence of alcohol and/or a drug. Benzodiazepine alone or in association with alcohol was surprisingly frequent. A serotonin syndrome may explain the agitation state.

Adolescent↗