Physicochemical and toxicological

Keywords Environmental and risk assessment models, Life-cycle Impact assessment models, Physicochemical and toxicological database... 

In order to run these models, it is necessary to have input data, mainly physicochemical properties and toxicological data (for both human and ecosystems), which can be extracted from different information sources. The source selection is essential to obtain data of high quality. In some cases (e.g., emerging pollutants) there is a lack of physicochemical and toxicological data which makes it necessary to use tools such as QSARs. 

In Table 3, a selection of physicochemical and toxicological databases is shown. These databases are selected according to the existence of quality controls and their free online availability. 

Table 3 Physicochemical and toxicological databases Database Description...

A selection of the most relevant physicochemical and toxicological estimation tools, which are freely available, are presented below in Table 4. 

Table 4 Most relevant QSAR tools to estimate physicochemical and toxicological properties Tool Description Ref...

In Germany, new chemicals are notified to the Federal Institute for Health Protection of Consumers and Veterinary Medicine (BgW). To provide a tool for the evaluation of physicochemical properties and probable toxic effects of notified substances, the BgW has developed a computerized database from data sets containing physicochemical and toxicological properties. The database has been used to develop specific SAR models for predicting skin and eye irritation/cor-rosion, which have been incorporated into a decision support system (DSS) (Gemer et al., 2000a 2000b Zinke et al., 2000). 

More than 30000 of the commercially available chemicals have recorded production volumes of greater than 1 tonne and, of these, 5200 are known as high volume production chemicals, produced in quantities of more than 1000 tonnes. It is difficult to know exactly how many chemicals are available in the marketplace at any one time but estimates are in tens of thousands and for the high volume production chemicals the manufacturers or importers are required to submit information suitable for risk assessment to the European Commission. The details include information available on the uses of the chemical and on the physicochemical and toxicological properties. From these details the Commission has prepared priority lists of potentially hazardous substances that require more detailed testing and assessment. 

Pinoxaden is a new graminicide for cereal crops developed by Syngenta [7]. It belongs to the AD chemical class. Table 9.6 summarizes its physicochemical and toxicological data. 

During the scoping step of an EIS, 3. first ranking of those components (e.g. metals and organics) is reconunended, which are classified as potentially hazardous either due to the amount produced, known physicochemical and toxicological characteristics, or in relation to their application and release pattern, their environmental occurrence, or due to a particular site susceptibility. 

Taking together the biological activity, the physicochemical and toxicological data, N-Cyclohexyl-benzo-thiophen-2-carboxamid-S,S-dioxid was the best candidate for the use in waterbased emulsion paints and was developed as Preventol TP OC 3082 and TP OC 3061 by Bayer. As can be seen from Table 2, it has a broad fungicidal and a slight algicidal activity. 

At the laboratory stage, data on substances involved and their mixtures must be gathered material properties, physicochemical data, ecological and toxicological data, costs of raw materials and intermediates, an estimate of product price, energy and equipment costs, etc. These data are needed in simulation programs and to determine toxicity, safety, and impact on the environment. The data on toxicity, degradability, and safety are required by the authorities to execute an approval procedure for the plant. 

Despite the existence of several databases for certain substances, it is not possible to find physicochemical and/or toxicological parameters to assess the risk for all substances. The lack of data is one of the main problems in risk assessment. This is especially true for emerging pollutants. One solution to solve this problem is the use of QSAR or estimation tools. QSAR models correlate the structure of the substance with their activities (physicochemical properties, environmental fate, and/or toxicological properties). 

The substance data required by the models (e.g., physicochemical parameters and toxicological data) have been normally extracted from different databases depending on the substance. In the present case, the information for both substances, lead and PBDE, were taken from the full Riskcycle Database is included in the CD not only the informations for the Pb and deBDE. 

Hardman, R. (2006) A toxicologic reviewof quantum dots toxicity depends on physicochemical and environmental factors. Environmental Health Perspectives, 114 (2), 165-172. 

Moreover, a-, p- and y-HBCD diastereoisomers are chiral. Thus HBCD have three pairs of enantiomers (+)a, (—)a, (+)p, (—)p, (+)y and (—)y. The enantiomers have identical physicochemical properties and abiotic degradation rates, but may have different biological and toxicological properties and therefore different biotransformation rates. These transformations may result in nonracemic mixtures of the enantiomers that were industrially synthesized as racemates [16, 19]. The rates of metabolisation process of the enantiomers of chiral environmental pollutants may be significantly different [20],... 

Some materials, by either their physicochemical or toxicological natures, generate difficulties in the performance and evaluation of dermal irritation tests. The most commonly encountered of these problems are presented below. 

S., Vatter, S., Chahbane, N., Lenoir, D., Schramm, K.W. and Scherer, G. (2005) Biological activity and physicochemical parameters of marine halogenated natural products 2,3,3, 4,4, 5,5 -heptachloro-l -methyl-1,2 -bipyrrole and 2,4,6-tribromoanisole. Archives of Environmental Contamination and Toxicology, 48, 1-9. 

The successful and possibly rapid degradation of toxic dye residues is of considerable importance form both a human and a veterinary toxicological point of view and for environmental protection. Because of the high amount of dyes loaded in the environment, much effort has been devoted to the development of physical, physicochemical and microbiological methods obtaining the degradation of dyes to non-toxic (even nutritive) derivatives. As has been previously mentioned, visible spectroscopic methods are widely applied for the measurement of the decomposition rate of dyes. However, when more than one dye molecule is simultaneously present or the primary decomposition products also absorb on... 

The physicochemical characteristics of X-ray contrast agents strongly determine their pharmacological and toxicological behaviour and are therefore import features, particularly in guiding the search for improved substances. 

In the chemical safety report, the hazard assessment of a particular substance is based on the data set provided in the technical dossier. This contains substance-specific information on physicochemical properties as well as on toxicological and ecotoxicological hazards. One objective of the hazard assessment is the substance s hazard identification, which comprises the determination of its physicochemical and hazardous properties for the purpose of classification. Concerning human health hazards, both human and nonhuman information is taken into consideration and evaluated with respect to the classification criteria laid down in the Dangerous Substances Directive and in the CLP Regulation, respectively. However, in most cases human data do not exist, so the hazard identification has to be based on data from animal experiments. With respect to teratogenicity, this hazardous property may in principle be detected in the following toxicity studies ... 

For experimental studies of mixtmes, consideration is given to the possibility of changes in the physicochemical properties of the test substance during collection, storage, extraction, concentration and delivery. Chemical and toxicological interactions of the components of mixtmes may result in nonlinear dose-response relationships. 

Possible transformation products can be numerous and their identification and assessment are both costly and time consuming. Transformation normally causes a change in the physicochemical and (eco)toxicological properties, that is, transformation products have different environmental fates and effects. A risk assessment of such compounds is often not feasible because these chemicals are not available in the amounts needed for testing, and their identities may not even be known. 

Figure 15.4 Structures of DDT, methoxychlor, and their major metabolites, and toxicological and key physicochemical properties. Data from [132, 135, 141, 210].

Lead optimisation is the synthetic modification of a biologically active compound, to fulfill all stereoelectronic, physicochemical, pharmacokinetic and toxicologic required for clinical usefulness (IUPAC). This phase begins with the first chemical lead or lead series selected for optimisation (i.e. the "lead series selected" milestone) and concludes with a decision for an optimized compound to enter preclinical development (i.e. the "pre-clinical candidate selected" milestone). This phase consists of testing of a compound to determine the chemical structure that has the optimum potency and selectivity for the target in question. The phase includes the search for backup compounds and may also include early ADME and toxicity evaluation. 

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