Possible toxicity

Sodium Nitrate and Sodium Nitrite. Nitrates and nitrites ate used in meat-curing processes to prevent the growth of bacteria that cause botulism. Nitrates have been shown to form low, but possibly toxic, levels of nitrosamines in certain cured meats. For this reason, the safety of these products has been questioned, and use is limited (80). 

Fig. 1. Periodic Table showing elements of importance in biological systems principal element of bioorganic compounds essential mineral nutrients for humans and other animals 1 essential mineral nutrient for animals, probably for humans M present in body, not known to be a nutrient or toxic element M element used in medicine element generally poisonous and present in body, possibly toxic.

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. 

Sulfur trioxide reactivity can also be moderated through the use of SO adducts. The reactivity of such complexes is inversely proportional to their stabihty, and consequentiy they can be selected for a wide variety of conditions. Whereas moderating SO reactivity by adducting agents is generally beneficial, the agents add cost and may contribute to odor and possible toxicity problems in derived products. CeUulosic material has been sulfated with SO.—trimethyl amine adduct in aqueous media at 0 to 5°C (16). Sulfur trioxide—triethyl phosphate has been used to sulfonate alkenes to the corresponding alkene sulfonate (17). Sulfur trioxide—pyridine adduct sulfates oleyl alcohol with no attack of the double bond (18). 

The following discussion on health and safety aspects of titanium compounds is concerned only with the behavior of the titanium present in inorganic compounds and not with the effects of the compounds themselves. For example, titanium tetrachloride must be treated with care because of the effects of the hydrochloric acid and heat produced when it reacts with water, not because of the possible toxicity of titanium. Apart from very few exceptions, the inorganic compounds of titanium are generally regarded as having low toxicity. Because of the ubiquitous nature of the element and its compounds, average concentrations of titanium in blood have been determined at 130—160 Fg/L (182—184), with a typical value of 10 Fg/L in urine (185). 

Calcium chloride is found in the marine environment. The elemental composition of seawater is 400 ppm calcium, 18,900 ppm chlorine, and many organisms and aquatic species are tolerant of these concentrations. Toxicity arises either from the invasion of freshwater in otherwise saltwater environments or possible toxic doses of calcium chloride from spills, surface mnoff, or underground percolation into typically freshwater streams or aquifers. Various agencies have guidelines for calcium and chloride in potable water (41). The European Economic Community (EEC) is the only agency to have a minimum specification for calcium in softened water. 

Often poly(ethylene glycol)s or derivatives thereof can be used instead of crowns or onium salts advantageously, although their catalytic activity frequently tends to be somewhat lower. The possible toxicity of crowns and cryptands and the price difference between these compounds and onium salts (100 1 to 10 1) are other important factors to be considered. Thus (1) [17455-13-9] (2) [14187-32-7] and (3) [16069-36-6] and cryptands are used more often in laboratory work, whereas onium salts are more important for industrial processes. 

In order to minimise the possible toxicity and damage to humans and the environment arising from the production and appHcations of colorants, an international association, the Ecological and Toxicological Association of the Dyestuff Manufacturing Industry (ETAD), was estabUshed in 1974. 

Neoprene latexes contain 0.5 to 0.02% residual chloroprene depending on the specific latex type. The amount of free alkaH in the water phase of latexes varies from 0.1 to 0.08% depending on type and age of the material. Eye protection and appropriate skin protection have been recommended for use in situations where splashes or spills are possible. Toxicity and safe handling practices have been recommended for Du Pont types (171). Since compositions may vary with other manufacturers, specific information should be obtained for other products. 

These materials are developed from the polyetherimides introduced by General Electric (see also Section 18.14.2). At the time of writing one grade, Ultem Siltem STM 1500, is being offered. It is of particular interest as a material for wire and cable insulation, as it not only has excellent flame resistance coupled with low smoke generation but also avoids possible toxic and corrosion hazards of halogenated polymers. This can be of importance where there are possible escape problems in the event of a fire, such as in tunnels, aircraft and marine (particularly submarine) vessels. 

Theoretically, this system offers the advantages of the thermal cure systems that include fast cure and low temperature processing. However, these systems are sensitive to atmospheric humidity and the possible toxicity of the catalyst may represent an issue. 

The Toxic Substances Control Act of 1976 was enacted by Congress to test, regulate, and screen all chemicals produced or imported into the U.S. Many thousands of chemicals and their compounds are developed each year with unknown toxic or dangerous characteristics. To prevent tragic consequences, TSCA requires that any chemical that reaches the consumer market be tested for possible toxic effects prior to commercial manufacture. Any chemical that poses health and... 

The characteristics of the downstream pollution discharge must be monitored (see Fig. 13.18). It is essential that the operation and maintenance of the pollution control equipment be included in a quality audit procedure, assisting in determining the operation efficiency of the equipment and the formation of unwanted and possibly toxic compounds in the pollution control steps. Unsuitable operation of an incinerator may result in partial oxidation and formation of unwanted combustion products or excessive formation of MO. 

The chemical industry uses esters for a variety of purposes. Ethyl acetate, for instance, is a commonly used solvent, and dialkyl phthalates are used as plasticizers to keep polymers from becoming brittle. You may be aware that there is current concern about possible toxicity of phthalates at high concentrations, although a recent assessment by the U.S. Food and Drug Administration found the risk to be minimal for most people, with the possible exception of male infants. 

The solubility (or insolubility) of different vitamins is of concern in nutrition. Molecules of vitamins B and C contain several —OH groups that can form hydrogen bonds with water (Figure 10.3). As a result, they are water-soluble, readily excreted by the body, and must be consumed daily. In contrast, vitamins A, D, E, and K, whose molecules are relatively nonpolar, are water-insoluble. These vitamins are not so readily excreted they tend to stay behind in fatty tissues. This means that the body can draw on its reservoir of vitamins A, D, E, and K to deal with sporadic deficiencies. Conversely, megadoses of these vitamins can lead to very high, possibly toxic, concentrations in the body. 

To test for possible toxic effects, rats, mice, dogs, chickens pigs, and fish were fed Pruteen at various levels in their diet, ranging from 30% to 60%. Control animals were fed casein (milk protein) instead of Pruteen. Feeding periods ranged from 28 days to 3 years. The parameters measured are outlined below. 

In fed-batch mode residual substrate concentration may be maintained at very low levels. Ibis would reduce substrate costs, may remove catabolic repressive effects and may avoid possible toxic effects of the substrate. The fed-batch mode of operation may also avoid oxygen depletion of the culture during rapid growth. 

In many countries starter batteries are almost 100 percent recycled PVC separators can cause some problems here [67]. A prior separation of PVC from other battery components, which is quite tedious, would be desirable, because a PVC content decreases the recycling purity of the container polypropylene and makes further processing of this plastic more difficult. Also, any chlorine compounds liberated can form environmentally hazardous products with other substances the usual remedy is to install costly filter stations, with the residues representing possibly toxic wastes requiring special disposal methods. 

In five pilot plants that can be used to simulate the route of anionic surfactants from the consumer via the effluent purification plant to the receiving water, possible toxic effects of residual surfactant content and breakdown products of the secondary alkanesulfonates were investigated [102]. As indicators of the effects on living organisms of the effluent in the receiving water, flora and fauna that are frequently encountered in the p-mesosaprobic zone were used as models. The embryo-larval test was also employed as an additional method for the detection of toxic compounds in the water. 

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. 

Various factors affect the activities of the enzymes metabolizing xenobiotics. The activities of these enzymes may differ substantially among species. Thus, for example, the possible toxicity or carcinogenicity of xenobiotics cannot be extrapolated freely from one species to another. There are significant differences in enzyme activities among individuals, many of which appear to be due to genetic factors. The activities of some of these enzymes vary according to age and sex. 

Evaluation of success is of primary importance. Loss of substrates is a necessary but not sufficient condition, in the light of the frequency of biotransformation reactions and the formation of terminal and possibly toxic metabolites. 

Mineral Oil Hydraulic Fluids. Aside from the possibility of the development of pneumonitis following the aspiration of ingested mineral oil hydraulic fluid, little is known regarding the toxicity of these materials. Additional animal studies to identify the possible toxic effects of exposure to these materials may provide information relevant to the investigation of methods for reducing the toxic effects. 

Maintaining the stability of a biological treatment of wastewaters containing formaldehyde and urea is complicated because some compounds exert a toxic effect on the processes involved. Figure 19.5 shows the possible toxic interactions between the different compounds and processes. 

The potential of the chemically modified nucleic acid molecules has been proven by in vitro studies however, the in vivo therapeutic applicability of these molecules seems to be unsatisfactory because of their possible toxic effects (largely unknown) and adverse bioavailability. In this view, both antisense and transfection technologies require reliable and efficient systems for their delivery into target cells. On the basis of this consideration, the development of an efficient nucleic acid delivery system represents one of the key steps for these therapeutic agents, which are necessary for a practical clinical utilization of natural or unnatural oligonucleotides. 

In this respect, an interesting approach to reduce degradation and possible toxicity problems related to nucleic acid use in vivo is offered by their encapsulation in or association to microcarrier systems, such as neutral or cationic liposome and polymeric microparticles [41 14],... 

Key study An AEGL-1 was considered to be inappropriate because significant irritation and possible toxic effects may occur at concentrations at or below the odor threshold and because of the exposure-response relationship exhibited by available toxicity data. ... 

Increased or decreased antidepressant response increased toxicity Decreased antihypertensive efficacy Decreased antihypertensive efficacy Increased hypoglycemic effects Possible additive lowering of seizure threshold Decreased antihypertensive efficacy tachycardia CNS stimulation Increased therapeutic and possibly toxic effects of both drugs hypertensive crisis delirium seizures hyperpyrexia serotonin syndrome Increased hypoglycemic effects... 

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