Registry Of Toxic Effects Of Chemical Substances Research Articles

Synthesis, characterization and antibacterial activity of imidazole-functionalized Ag/MIL-101(Cr)

Nowadays, nanomaterials have rapidly developed as a new generation of antibacterial agents. However, high local aggregation and concentration, and possible toxicity due to excess leaching are disadvantages of nanoparticles. Unique features of metal–organic frameworks (MOFs) such as coordinately unsaturated centers, high surface area and facile synthesis attracted attention to overcome the above-mentioned problems. In this context, Ag/MIL-101(Cr)/IMI was synthesized, and after characterization by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM–EDX), Transmission Electron Microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), inductively coupled plasma-optical emission spectrometry and BET surface area, TG–DTA was used as an antibacterial agent. Imidazole-functionalized Ag/MIL-101(Cr)/IMI presented a synergistic effect of imidazole and silver NPs against Escherichia coli (ATCC25292) and Staphylococcus aureus (ATCC25293) bacteria. The best antibacterial activity as minimum inhibitory concentration (MIC) was 6.2 µg/mL and 24.78 µg/mL of silver content against E. coli and S. aureus, respectively. There were 81 and 144.9 mg of Ag and imidazole per each gram of Ag/MIL-101(Cr)/IMI, which leaching rates of Ag, imidazole and Cr were 150, 828 and 153 µg/L, respectively. This leaching level of imidazole was lower than the amount recommended by Registry of Toxic Effects of Chemical Substances (RTECS) from NIOSH, while the leaching levels of silver NP and chromium is tended to be around the standard of WHO and U.S.EPA.

QSAR models of the inhalation toxicity of organic compounds

Results of QSAR research for chemical inhalation toxicity are presented. Data on the inhalation toxicity of organic compounds (403 chemicals) with respect to rats (4-h exposure) were taken from the Registry of Toxic Effects of Chemical Substances (RTECS). Among these, 28 inert chemicals with nonspecific toxicity were selected. Regression models were formed for all these compounds. The QSAR models were constructed using two approaches based on (i) experimental values of octanol—air partition coefficients and (ii) molecular physicochemical descriptors calculated by the HYBOT program. The best computer model was obtained on the basis of molecular physicochemical descriptors. A comparison of the inhalation toxicity of all examined compounds with the base nonspecific toxicity identified additional compounds with toxicity close to the base level that were not inert; a class of compounds with substantially greater toxicity (specific toxicants); and a class of compounds with substantially less toxicity due to metabolism. Satisfactory classification and regression QSAR models were obtained for 135 substances in the examined set with similar structures.

Application of QSARs: Correlation of Acute Toxicity in the Rat Following Oral or Inhalation Exposure

AbstractQuantitative Structure‐Activity Relationships (QSARs) based upon a lethal narcosis mechanism represent baseline or minimum toxicity, i.e. unless a chemical acts by a more specific mechanism, its toxicity will be predicted by such models. Baseline toxicity should be independent of exposure route. A toxicity ratio (TR) is defined as the ratio of the calculated baseline toxicity over the experimentally determined value. A TR‐value of approx. 1 indicates baseline toxicity. A TR‐value greater than 1 indicates excess toxicity due to the existence of a more specific mechanism of action. We investigated the possibility of extrapolation from the inhalation route to the oral route by applying the above concepts.

Searching for hazardous substances on the Internet

Environmental research professionals, occupational health professionals, and safety engineers rely on fast access to data on chemical substances known to be hazardous to human health and the environment. Such factual substance data can be found in Material Safety Data Sheets (MSDS) provided by manufacturers of chemicals, traditional databases such as the Registry of Toxic Effects of Chemical Substances (RTECS) or the Hazardous Chemicals Data Base (HSDB), and with the help of search engines or portals on the free Internet. The questions investigated in this paper are: can the WWW be used as a source for reliable data on chemical compounds? And can particular search services be recommended for particular questions? Recommendations for searching information about chemicals on the Internet are given.

The relative toxicity of compounds in mainstream cigarette smoke condensate

Many different in vivo and in vitro tests are currently used to assess the toxicity of chemicals and complex mixtures such as cigarette smoke condensate. In vivo tests include assays in rodents to determine carcinogenicity, tumorigenicity and reproductive effects. In vitro tests of mutagenicity are conducted with both bacterial and mammalian cell systems. A first step towards lowering the toxicity of cigarette smoke condensate is the identification of the relevant compounds. However, changing the concentration of a given smoke component may not linearly alter the biological activity of the complex mixture due to interactive effects. The “effective toxicity” of a chemical constituent is a function of the concentration, the metabolic fate, the potency in in vivo and in vitro assays, and the ability to reach the target tissues. The logarithm of the octanol–water partition coefficient (log P) is an important parameter since it affects metabolism, biological transport properties and intrinsic toxicity. Using concentration data from the International Agency for Cancer Research (IARC), biological activity data from the Registry of Toxic Effects of Chemical Substances (RTECS) database and measured and calculated log P values, we have rank ordered some of the important compounds in cigarette smoke condensate by their measured or potential toxicity. Condensates from different cigarette brands, tar categories and styles vary in their concentrations of these compounds. Chemicals of greater commercial or scientific interest may be toxicity tested more extensively, thereby increasing the probability of positive test results and highlighting the need for consideration of structure–activity relationships.

Predictive toxicology of chemicals and database mining

The toxic chemicals from the database Registry of Toxic Effects of Chemical Substances (RTECS) were analyzed by structural similarity comparison, which shows that the structure patterns or characteristics of toxic chemicals exist in a sufficiently large database. Then, a two-step strategy was proposed to explore noncongeneric toxic chemicals in the database: the screening of structure patterns by similarity comparison and the derivation of detailed relationship between structure and activity by using comparative molecular field analysis (CoMFA) of Quantitative Structure-Activity Relationship (QSAR) technologies. From the performance of the procedure, such a stepwise scheme is demonstrated to be feasible and effective to mine a database of toxic chemicals. It can be anticipated that database mining of toxic chemicals will be a new area for predictive toxicology of chemicals.

The contribution of acute toxicity in animals to occupational exposure limits of chemical substances.

The correlations of lethal doses of various industrial chemicals for rats and mice with occupational exposure limit values were investigated. 50% lethal dose (LD50) values obtained by oral (p.o.) and intraperitoneal (i.p.) injection and 50% lethal concentration (LC50) values obtained by inhalation exposure were collected from Registry of Toxic Effects of Chemical Substances (RTECS). Threshold Limit Value (Time-Weighted Average) (TLVs-TWA) and Threshold Limit Value (Short Term Exposure Limit) (TLVs-STEL) recommended by American Conference of Governmental Industrial Hygienists (ACGIH) were used as exposure limits. TLVs-TWA or TLVs-STEL and LD50 or LC50 values obtained for the rats were plotted on logarithmic scales on the ordinate and abscissa, respectively. High correlations were obtained between these parameters. The order of correlations was: TLVs-STEL vs. LC50s > TLVs-TWA vs. LC50s > TLVs-TWA vs. LD50s i.p. > TLVs vs. LD50s p.o. The same calculations for the relationship between TLVs and lethal doses in mice were also performed. The order of the three types of correlations was same as that of the rats; however, correlation coefficients for TLVs-STEL vs. LC50s and for TLVs-TWA vs. LC50s obtained in mice were smaller than those in rats. TLVs-TWA are, therefore, well correlated with LC50 values rather than LD50 values, particularly with those in rats. High correlations between TLVs-STEL vs. LC50s were also obtained, as had been expected before calculation. The equation: TLV-TWA = 10b x (LC50)a can be obtained from these plottings, where the values a and b are taken from each linear regression line. TLV-TWA for each chemical can be calculated by using LC50 and the equation. The upper and lower 95% confidence limits for calculated TLV-TWA were TLV-TWA (calculated from LC50) x 22.9 and TLV-TWA (calculated)/22.9, respectively, where LC50 for rats expressed in ppm x hr was used.

1997 Herbert Stokinger Lecture

Abstract The Registry of Toxic Effects of Chemical Substances (RTECS), formerly the Toxic Substances List, was started at the same time that the National Institute for Occupational Safety and Health was founded at the end of 1970. It was mandated then that the first list be published by June 28, 1971, and subsequently that it be published periodically, at least annually. This congressional mandate has been met faithfully since the Occupational Safety and Health Act was passed. At times when there have been budgetary constraints, continuation of the RTECS publication has been threatened. The loss of RTECS would essentially remove the expanding technical support upon which users depend for information on chemical hazards, and thus their basis for protection from exposures, particularly to lesser-known and -used chemical substances. Neither national, state, nor local occupational health agencies can allot sufficient budgetary resources to properly monitor and control these exposures. By increasing the variety of datafields to include more hazard descriptive data, RTECS will more thoroughly describe the nature of the hazards associated with the use of any substance and will assist the users of the substances to prevent exposure-related illnesses and deaths. Therefore, RTECS will never be completed nor finished.

Comparison of the Gene-Tox and RTECS data bases as predictors of carcinogenic potency

Travis et al. (1990a,b) developed a method to predict thq carcinogenic potency of known mouse carcinogens using different classes of short-term toxicologic data. The method is based on a relative potency analysis of toxicological data from the Registry of Toxic Effects of Chemical Substances (RTECS) data base (Sweet, 1987) developed by the National Institute of OccupationJ Safety and Health (NIOSH). Rather than rely solely on genotoxicity data to predict carcinogenic potency as has been done in the past (McCann et al., 1988; Piegorsch and Hoel, 19881, Travis et al. (1990a,b) make use of all available toxicologic information in RTECS (e.g. genotoxicity, cytotoxicity, reproductive effects, and chronic and subchronic tumorigenicity). The methodology em-

Quantitative correlation of carcinogenic potency with four different classes of short-term test data

The search for a short-term mutagenicity test to identify potential carcinogens has yielded over 100 assay systems, including the Ames test. This paper continues the investigation of Travis et al. into the prediction of carcinogenic potency of known mouse carcinogens using different classes of short-term toxicologic data. We used four classes of short-term test data (mutation, toxicity, reproduction and tumorigenicity) from the Registry of Toxic Effects of Chemical Substances (RTECS) database. We conclude that mutation data alone are poor predictors of carcinogenic potency, accounting for only 21% of the observed variability in experimentally-determined mouse TD50 values. We further conclude that batteries of toxicologic data containing varying types of short-term data are excellent predictors of the carcinogenic potency of known mouse carcinogens: four types of short-term data account for 82% of the observed variability in experimentally-obtained mouse TD50 values. By using all available toxicological data, we obtained a strong correlation between toxicologic assay results and carcinogenic potency of known mouse carcinogens.

Computer data bases for carcinogenicity and risk assessment

AbstractThis paper reviews information on computer data bases for carcinogenicity and risk assessment. The data bases included were Chemical Evaluation Search and Retrieval System (CESARS), Hazardous Substances Data Bank (HSDB), Registry of Toxic Effects of Chemical Substances (RTECS), Toxicology Information Online (TOXLINE), Cancer Literature (CANCERLIT), Chemical Carcinogenesis Research Information System (CCRIS), Public Health Risk Evaluation Database (PHRED) and Integrated Risk Information System (IRIS). Chemical records included in CESARS, HSDB and RTECS contain general information on carcinogenicity. TOXLINE and CANCERLIT are bibliographic data bases for toxicological and cancer studies. CCRIS contains detailed information on carcinogenicity studies for formulation of risk assessment. PHRED contains toxicological information and cancer potency factors for formulation of risk assessment. IRIS provides detailed information for carcinogenicity assessments, slope factors, unit risks and concentrations at specified risk levels for chronic exposures to carcinogens. IRIS serves as the best source of information for risk assessment for environmental contaminants.

Evaluations using test queries of chemical hazards databases and databanks

This paper consists of short reports on three projects which evaluated online chemical hazards services. Two were studies of bibliographical databases and one a study of databanks. Test queries were used in the evaluations. The chemical hazards bibliographic databases studied were HSEline, CISDOC, Laboratory Hazards Bulletin (LHB), Chemical Hazards in Industry (CHI), Occupational Health and Safety (NIOSH), Safety Science Abstracts (SSA), EMBASE, BIOSIS, MEDLINE and CASearch. The main conclusion reached was that whilst all the databases included relevant references none provided comprehensive coverage for the test queries. HSEline produced the highest number of relevant references and LHB and CHI also performed well, but most of the other databases were useful for some of the queries. The chemical hazards databanks compared were RTECS (Registry of Toxic Effects of Chemical Substances), HSDB (Hazardous Substances Data Bank), OHMTADS (Oil and Hazardous Materials - Technical Assistance Data - system), BAKER, CHRIS (Chemical Hazards Response Information System) and CESARS (Chemical Evaluation Search and Re trieval System). The main conclusions of the evaluation were that HSDB gives the widest subject coverage and has the longest datasheets. Its coverage of animal toxicology is as good as that of RTECS. HSDB is the best source for human toxicity information and has the same amount or more information than BAKER and CHRIS on emergency actions. RTECS concentrates on toxic effects and has little information on physical/chemical properties, manufacture, emergency han dling, chemical reactions or explosive properties. OHMTADS does not contain first aid procedures but gives concise infor mation on other emergency actions. BAKER and CHRIS are useful for substance identification, waste management and emergency spill procedures.

Photobacterium phosphoreum toxicity bioassay. II. Toxicity data compilation

AbstractThis review of Photobacterium phosphoreum toxicity bioassay, commonly known as the Microtox tests, consists of two parts. This second part (Toxicity Data Compilation) is a listing of all published and certain unpublished Microtox toxicity data for single organic compounds, including some salts and organometallic compounds. This listing consists of three tables: the first provides the reference source, toxicity value(s), chemical formula, name, the Chemical Abstracts Service (CAS) and Registry of Toxic Effects of Chemical Substances (RTECS) accession numbers, and molecular weight of each compound. At present, this table contains approximately 500 entries, which are ordered by the compounds' molecular formula. Two additional tables, ordered accordingly, are intended to provide quick access through cross‐references with the CAS and RTECS numbers, respectively.

Chemical scoring by a rapid screening of hazard (RASH) method.

A rapid screening of hazard method (RASH) is presented for deriving relative potency estimates for hazardous substances. The method utilizes data from any available toxicological database such as the Registry of Toxic Effects of Chemical Substances (RTECS) or EPA's GENE-TOX database on genetic activity profiles. The method has been applied to derive relative potency values and permissible environmental concentrations for 278 chemicals. The derived values have been compared with recommendations of expert committees where possible, and substantial agreement is found.

An evaluation of information sources in household product poisoning

Little work has been published on the identification or comparison of information sources in the area of household chemical poisoning. Therefore, this study was set up to evaluate the performance of 11 sources in providing information to answer a selected set of 30 questions. The sources were: 2 on-line bibliographic databases: TOXLINE (TOXL), Excerpta Medica (EMED), one databank: Registry of Toxic Effects of Chemical Substances (RTECS), 6 textbook sources and two National Poisons Information Service in-house databases (Poi sons Index, Clinical Case Reports File). The evaluation was made on the basis of completeness of information provided and search time. The retrieved references from TOXL and EMED were analysed for their relevance. The in-house data bases performed better than the other 9 sources in terms of speed of provision and completeness of information on household product poisoning. The search times (time taken to obtain original articles) using TOXL and EMED were high, although their information retrieval was as good as or better than that of the textbook sources. The RTECS databank provided no useful information. The needs of a poisons infor mation service are best served by a purpose-built in-house database, based on its own clinical case data, supplemented by external sources where necessary. The system would be im proved by computerization.

Improvements in the NIOSH registry of toxic effects of chemical substances.

Subsequent to the publication of the 1977 edition of the NIOSH Registry of Toxic Effects of Chemical Substances (RTECS), several additions and changes were introduced that substantially improved the content and accessibility of the RTECS data file. Content additions included primary irritation data for both skin and eyes, in vitro mutagenicity data, and citations to toxicology review articles and to the Toxic Substances Control Act inventory. Also undertaken was a re-evalution of existing tumorigenic entries based on revised selection criteria. Accessibility to RTECS data has been facilitated by the introduction of on-line interactive computer searching, and the preparation and distribution of Computer Output Microfiche (COM-fiche) and magnetic tape copies of the file which supplement the annual publication.

Analysis of the registry of toxic effects of chemical substances (RTECS) files and conversion of the data in these files for input to the environmental chemicals data and information network (ECDIN).

A data bank for environmental chemicals, ECDIN, is being developed at the Joint Research Centre of the European Communities in cooperation with universities and research institutes in the nine member states as a part of the Environmental Research Programme of the EC. During the pilot phase of the project, data from the Registry of Toxic Effects of Chemical Substances have been incorporated into the data bank. Conversions of the data into ECDIN input format was necessary before inclusion of the toxicity data in ECDIN, and the computer programs used for this format conversion have produced various statistics for the contents of the RTECS files. Analyses of the data in three editions of RTECS are presented.