Toxic Toxicological properties

Health and Safety Factors. MEK is slightly more toxic than acetone, but is not considered highly toxic, and nor does it exhibit cumulative toxicological properties. The OSHA time weighted average iu air is 200 ppm other measured toxicity values are shown iu Table 3. Methyl ethyl ketone is highly flammable. 

Neady every significant class of dyes and pigments has some members that function as sensitizers. Toxicological data are often included in surveys of dyes (84), reviews of toxic substance identification programs (85), and in material safety data sheets provided by manufacturers of dyes. More specific data about toxicological properties of sensitizing dyes are contained in the Engchpedia under the specific dye classes (see Cyanine dyes Polymethine dyes Xanthene dyes). 

Not all contaminants or chemicals are created equal in their capacity to cause adi ersc effects. Thus, cleanup standards or action levels are based in part on the compounds toxicological properties. Toxicity data are derived largely from animal experiments in which llie aninuils (primarily mice mid rats) are exposed to increasingly liighcr concentrations or doses. Responses or effects can vary widely from no obscn ablc effect to temporary and reversible effects, to permanent injury to organs, to chronic functional impairment to ultimately, death. 

Toxicology Many companies are known to use gene expression profiling to assess the potential toxicity of lead compounds. This approach may require a database of reference compounds with known pharmacological and toxicological properties. Lead compounds can be compared to the database to predict compound-related or mechanism-related toxicity [5]. 

Studies on the chlorodibenzodioxins have led to the following conclusions (1) 2,7-dichlorodibenzo-p-dioxin and octachlorodibenzo-p-di-oxin have a low acute toxicity (2) 2,3,7,8-tetrachlorodibenzo-p-dioxin has an unusually high toxicity (3) hexachlorodibenzo-p-dioxin is highly toxic but less toxic than 2,3,7,8-tetrachlorodibenzo-p-dioxin (4) all chlorodibenzodioxins are not alike in their toxicological properties. Isomers of the same dibenzo-p-dioxin vary in toxicological properties, making it important to identify them specifically. 

Toxicological properties Acute toxicity (by two routes of admission) Skin irritation... 

It is advisable, then, in a tiered approach to concentrate first on crops and activities (scenarios) that are considered to be relevant with respect to the expected level of exposure and to exclude those not relevant. Second, whether or not the toxicological properties of the product may lead to general restrictions on re-entry should be investigated. If both the likelihood of reentry and the hazard due to the toxicity of the compound cannot generally be neglected, a risk assessment over several steps should be carried out. The assessment may be based on surrogate data and "worst-case" assumptions at first and then refined, if necessary. One possible approach to a tiered evaluation procedure is presented in Figure 1. 

Toxicological properties Acute toxicity (by two routes of admission) Skin irritation Eye irritation Skin sensitization 28 days subacute toxicity Ames test In vitro metaphase analysis (or mouse micronucleus test)... 

Not all crown ethers have been tested for ecological or toxicological properties. Some are irritants and some are known to be toxic, although those tested do not show high toxicity. Nevertheless, amongst those that have not been tested, some may be hazardous to health. 

Complex cyanides are compounds in which the cyanide anion is incorporated into a complex or complexes. These compounds are different in chemical and toxicologic properties from simple cyanides. In solution, the stability of the cyanide complex varies with the type of cation and the complex that it forms. Some of these are dissociable in weak acids to give free cyanide and a cation, while other complexes require much stronger acidic conditions for dissociation. The least-stable complex metallocyanides include Zn(CN)42 , Cd(CN)3 , and Cd(CN)42 moderately stable complexes include Cu(CN)2, Cu(CN)32, Ni(CN)42, and Ag(CN)2 and the most stable complexes include Fe(CN)64, and Co(CN)6. The toxicity of complex cyanides is usually related to their ability to release cyanide ions in solution, which then enter into an equilibrium with HCN relatively small fluctuations in pH significantly affect their biocidal properties. 

Ideally, a full data set should be available for the hazard assessment of a chemical substance, including animal tests to evaluate the toxicokinetics and the following toxicological properties acute toxicity, irritation, sensitization, toxicity following repeated exposure to the substance, mutagenicity and genotoxicify, carcinogenicity, and effects on fertility and fetal development. 

When data do not exist for a given toxicological endpoint, or when data are limited, the use of SARs may be considered in the hazard assessment. The potential toxicity of a substance, for which no or limited data are available on a specific toxicological endpoint can, in some cases, be evaluated by read-across from structurally or mechanistically related substances for which experimental data exist. The read-across approach is based on the principle that structurally and/or mechanistically related substances may have similar toxicological properties. 

The aim of the hazard assessment of a chemical substance under evaluation is to assess whether exposure to the chemical might result in adverse health effects in humans, based on a critical evaluation of the available data on the inherent toxicological properties of the substance as well as the toxicological mode(s) of action/mechanisms of toxicity. 

Thus, the hazard identification, in addition to an identification of the inherent toxicological properties (type of effects), also involves an evaluation of the nature of the observed effects, i.e. (1) whether an observed effect constitutes an adverse effect and thus results in an impairment of body function(s), and (2) whether an effect is a direct toxic effect exerted by the chemical (biologically relevant) or is due to normal unspecific reactions toward changes in the environment (homeostasis). Examples of effects, which generally are not considered as being adverse, include ... 

Testing of the whole mixture as such has been recommended for mixtures that are not well characterized (Mumtaz et al. 1993), and has successfully been applied for assessing the combined toxicity of simple, defined chemical mixtures where the toxicological properties of the individual components were also investigated, see Section 10.6. 

Methyl and ethyl mercury compounds have similar toxicological properties, and there is no sharp demarcation between acute and chronic poisoning. Once a toxic dose has been absorbed and retained for a period of time, functional disturbances and damage occur. The latency period for a single toxic dose may vary from one to several weeks longer latency periods on the order of years have been reported for chronic exposures. ... 

This compound was much less toxic to the white mouse but comparable to carbofuran in insecticidal activity. Toxicological properties for some of these compounds are presented in Table III. It is apparent from the data that the thiobiscarbamates... 

Most of the -sulfinyl derivatives in the table show good insecticidal activity along with a significant reduction in mouse toxicity (2- to 25-fold reduction). The number of new derivatives with Improved toxicological properties which can be synthesized through the N-chlorosulfinyl intermediates is exceedingly large. 

The anhydrous form is rarely if ever used for catalysis, as is the case with anhydrous RuOj. It exists in two modifications. The black a-form is made by heating P-RuClj to 600°C in vacuo, and has the laminar a-TiClj structure also found in CrClj and FeClj with a distorted octahedral structure (Ru-Cl distance 2.40 A). The brown P-form has the P-TiClj structure with linear polymers of RuClj units, the metal atoms having distorted octahedral coordination (Ru-Ru 2.68 A, Ru-Cl 2.30(7) and 2.39(7) A). Infrared spectra and magnetic susceptibility data were recorded for both forms [712]. The toxicological properties of RuClj have been listed it may give off toxic RuO when heated, and is mildly toxic by intraperito-neal routes [238]. 

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