Possible toxicity properties

Regarding the persistence of bound residues, as compared to the parent compound and other metabolites, and their high bioavailibility when fed to rats (63), special attention was paid to their identity and possible toxic properties. In particular the possible presence of reversible protein-bound metabolites in tissues of treated animals was hypothesized to imply a possible health-risk for the consumer (63). The issue of bound-residues of furazolidone and other drugs has long been one of the most controversial and difficult problems in the field of residue toxicology (64, 65). 

No toxicological studies have been reported on the triple salt. However, because of the common confusion of this compound with potassium hydrogen monoperoxosulfate monohydrate, it is possible that the pubHshed descriptions of the toxic properties of this latter compound actually refer to the triple salt. If this is so, then the triple salt must be regarded as toxic and irritating to skin, eyes, and mucous membranes (2). 

The widespread sales of this plasticizer are a redection of its all-around plasticizing performance and its provision of adequate properties for a great many standard products. It possesses reasonable plasticizing efficiency, fusion rate, and viscosity which, coupled with the normally competitive price, go a long way to explaining the popularity of this plasticizer. Some concerns have been periodically raised as to the possible toxicity of this material, but it can be said that these concerns are often related to the vast and widespread study of the toxicity of DEHP. 

Waste water rules have pH limits, a common range being between 6 and 10. There are also limits for fats and oils, solvents, heavy metals, and a variety of other compounds and ions. The fact that a compound with possible toxic or otherwise undesirable properties is not on the list does not mean it is permissible. Such a matter should be discussed with the proper authorities. The discharged water may also have to pass a test for toxicity to aquatic animals. As one frustrated manager of a chemical plant put it We can no longer put anything but pure tap water into the sewer Of course, it is not really that bad, but some of the requirements often come as a surprise. 

Although the initially reported tissue compatibility tests for subcutaneous implants of poly(BPA-iminocarbonate) were encouraging (41,42), it is doubtful whether this polymer will pass more stringent biocompatibility tests. In correspondence with the properties of most synthetic phenols, BPA is a known irritant and most recent results indicate that BPA is cytotoxic toward chick embryo fibroblasts in vitro (43). Thus, initial results indicate that poly(BPA-iminocarbonate) is a polymer with highly promising material properties, whose ultimate applicability as a biomaterial is questionable due to the possible toxicity of its monomeric building blocks. 

Measurement of exposure can be made by determining levels of toxic chemicals in human serum or tissue if the chemicals of concern persist in tissue or if the exposure is recent. For most situations, neither of these conditions is met. As a result, most assessments of exposure depend primarily on chemical measurements in environmental media coupled with semi-quantitative assessments of environmental pathways. However, when measurements in human tissue are possible, valuable exposure information can be obtained, subject to the same limitations cited above for environmental measurement methodology. Interpretation of tissue concentration data is dependent on knowledge of the absorption, excretion, metabolism, and tissue specificity characteristics for the chemical under study. The toxic hazard posed by a particular chemical will depend critically upon the concentration achieved at particular target organ sites. This, in turn, depends upon rates of absorption, transport, and metabolic alteration. Metabolic alterations can involve either partial inactivation of toxic material or conversion to chemicals with increased or differing toxic properties. 

The disulphonated DAST derivative 11.25 containing four anilino groups per molecule is effective in liquid detergent formulations and much cheaper to manufacture than the monosulphonated DAST brightener 11.67, which was withdrawn from the market in the late 1980s. It has been necessary to purify compound 11.25 specially for use in detergents, in order to eliminate traces of residual unreacted aniline as far as possible, owing to the toxic properties of this impurity. 

It is time to inquire about the methods used to identify the toxic properties of chemicals. So far a few key principles have been introduced and some information on specific substances has been discussed, but little has been said about how these principles and information have been learned. Without some appreciation of the basic methods of toxicology, and what can and cannot be accomplished with them, it will not be possible to gain a solid understanding of the strengths and, more importantly, the limitations in our knowledge of chemical risk. 

The acute toxic properties of all the organochlorine pesticides in humans are qualitatively similar. These agents interfere with inactivation of the sodium channel in excitable membranes and cause rapid repetitive firing in most neurons. Calcium ion transport is inhibited. These events affect repolarization and enhance the excitability of neurons. The major effect is central nervous system stimulation. With DDT, tremor may be the first manifestation, possibly continuing to convulsions, whereas with the other compounds convulsions often appear as the first sign of intoxication. There is no specific treatment for the acute intoxicated state, and management is symptomatic. 

These mixtures can be exploded by an electric discharge or by sparks from steel tools etc. Bronze is much safer in that respect and bronze tools should be used wherever possible. Beryllium bronze was strongly recommended at one time. However the toxic properties of beryllium limit its application. 

We should keep in mind that the term "pesticide" refers to a chemical use category and not a specific chemical characteristic. It does impart the knowledge that a substance has toxic properties which can be used to advantage. Only with proper chemical characterization of residues found in the body and knowledge of their potential influence on homeostasis will it be possible to dispel popular misconceptions to the effect that pesticide chemicals are handled differently from other chemicals which enter the body or are unique in the hazards they present to the system. 

Chemical finishes can be durable, i.e. undergo repeated launderings or dry cleanings without losing effectiveness, or non-durable, i.e. intended when only temporary properties are needed or when the finished textile typically is not washed or dry cleaned, for example some technical textiles. In nearly all cases, the chemical finish is a solution or emulsion of the active chemical in water. Use of organic solvents to apply chemical finishes is restricted to special applications owing to the expense and the real or possible toxicity and flammability of the solvents employed. 

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