Solvents toxic effects

Chlorinated organic compounds (dioxins, other halocarbons) Combustion of municipal wastes, paper processing, cleaning solvents Toxic effects including birth defects, reproductive failure, cancer, and systemic poisoning. 

Mutti, A., Falzoi, M., Romanelli, A., Bocchi, M.C., Ferroni, C. Franchini, 1. (1988) Brain dopamine as a target for solvent toxicity effects of some monocyclic aromatic hydrocarbons. Toxicology, 49, 77-82... 

Toxic effects of chemicals can range from mild and reversible (e.g., headache from inhaling petroleum naphtha vapors that disappears with fresh air) to serious and irreversible (e.g., liver or kidney damage from excessive exposures to chlorinated solvents). Toxic effects from chemical exposure depend on the severity of the exposures. Greater exposure and repeated exposure generally lead to more severe effects. 

SAN resins themselves appear to pose few health problems in that they have been approved by the EDA for beverage botde use (149). The main concern is that of toxic residuals, eg, acrylonitrile, styrene, or other polymerization components such as emulsifiers, stabilizers, or solvents. Each component must be treated individually for toxic effects and safe exposure level. 

The effects of occupational exposure to lindane have been investigated extensively (96—100). These studies indicated that occupational exposure to lindane resulted in increased body burdens of this chemical however, toxic effects associated with these exposures were minimal and no central nervous system disorders were observed. This is in contrast to the polyneuropathies that are often observed after exposure to other haloorganic solvents. 

Solvent wiping. Rubbers tend to swell by application of solvents and the mechanical interlocking of the adhesive is favored. Although chlorinated hydrocarbon solvents are the most effective, they are toxic and cannot be used toluene and ketones are currently the most common solvents. The treatment with solvents is effective in the removal of processing oils and plasticizers in vulcanized mbbers, but zinc stearate is not completely removed and antiozonant wax gradually migrates to the mbber/polyurethane adhesive interface. Table 27.1 shows the moderate increase in adhesion produced in SBR by MEK wiping. 

With some insecticides the physical state of a residual deposit has a pronounced effect upon its toxic effect. This is especially true of technical DDT, which tends to remain in viscous droplets when released from solution in volatile solvents. These may remain... 

One method of overcoming the detrimental solvent dewetting effects is to use liquid C02 as the solvent for nanoparticle dispersions [52], since C02 does not experience the dewetting instabilities due to its extremely low surface tension [53]. In this case, nanoparticles must be stabilized with fluorinated ligands [30, 33, 54—65] or other C02-philic ligands [60,66-76], such that they will disperse in the C02 prior to dropcasting. These fluorinated ligands tend be toxic and environmentally persistent and, typically, only very small nanoparticles can be dispersed at low concentrations. 

Halogen content If halogens in the anion are not crucial for specific reactions performed in the ionic liquid, they should be avoided. Moisture sensitivity, halogenide transfers, alcoholysis and toxic effects are often connected with halogen atoms in the molecule [27]. In addition, the hydrolysis products HCl or HF act corrosively. Within the project reported by Wasserscheid and coworkers they successfully developed ionic liquids with alkylsulfate groups as anions to overcome the halogen content. These new solvents show very favorable properties. 

However, this may not be true the volume of the vehicle may be more than an animal (particularly a small animal such as a mouse) can handle, or the pH may produce toxic effects. To separate these factors, a large scale study was undertaken to determine the toxicity of certain commonly used solvents. 

Toxicology. Methyl ethyl ketone (MEK) is an irritant of the eyes, mucous membranes, and skin, and at high concentrations it causes nervous system effects MEK potentiates the toxic effect of other solvents. 

The toxicology of a solvent is determined by many factors, such as bioavailabihty, metabolism, and the presence of structural features that may attenuate or enhance the reactivity of the parent molecule. Despite the structure-activity data available for many classes of commercial chemical substances, chemists have not recognized the use of structure-activity relations as a rational approach for choosing or designing new, less toxic commercial chemical substances. With qualitative structure-activity relationships, comparing the structures of the substances in the series with corresponding effects on the toxicity makes the correlation between toxic effect and structure. Through these, it may then be possible to predict a relationship between structure and toxicity... 

Environmental toxicity considerations for choice of solvents include the degree of absorption reported in the literature, exploration of toxic mechanisms, and the use of Stmcture-Activity Relationships (SAR). The relative seriousness of the toxic effect depends upon the extent of exposure to the substance, its bioavailability, and the importance of the physiologic process that the substance has disrupted (DeVito, 1996a). Over this information must be laid the physical parameters of the solvent s use (i.e., amount, state, reaction environment, etc). This requires a basic understanding of the processes involved in chemical toxicokinetics and toxicodynamics. 

The toxic effect on biocatalytic activity and stability in two-phase reaction system media can be divided into two effects. The first one, called the molecular-toxicity effect, is a direct toxic effect of the solvent molecules, which are dissolved in the aqueous phase and interact with the biocatalyst, particularly with whole cells. The second one, which is created by the presence of an interface between the aqueous and the organic solvent phase, is called the phase-toxicity effect [2, 24]. 

Residual solvents are divided into three classes. Class 1 solvents are those known to cause toxic effects and should be avoided in the production of active substances and excipients. Class 2 solvents present less severe toxicity than class 1, and class 3 solvents have such low toxic potential that exposure limits are not necessary. Table 12 presents the general characteristics of the solvents included in each class, and Table 13 lists the solvents and their concentration limit in pharmaceutical products. 

Organonitriles are organic substances that contain the cyano (-C = N) group. Nitriles have wide commercial applications that include solvents, synthetic intermediates, pharmaceuticals, and monomers, to name just a few. As a class of substances, there are two types of toxicity associated with exposure to nitriles acute lethality and osteolathyrism. Some nitriles are known to cause both. The mechanisms by which nitriles cause these toxic effects, the corresponding relationships between nitrile structure and toxic potency for each effect, and the use of this information as a basis to design substances that may need to contain the functionality of the cyano group but will cause minimal toxicity have been discussed in detail [7]. Only the biochemical mechanism and SARs related to acute lethality of nitriles are discussed here. More detailed discussions are available [7, 8, 61]. 

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