Toxicity to Animals

CgH,3BrN202. A soil-acting herbicide. White crystalline solid, m.p. 158-159" C. It is a non-selective inhibitor of photosynthesis used for weed control In citrus and cane fruit plantations. It is relatively non-toxic to animal life. 

Fluoroacetic acid [144-49-OJ, FCH2COOH, is noted for its high, toxicity to animals, including humans. It is sold in the form of its sodium salt as a rodenticide and general mammalian pest control agent. The acid has mp, 33°C bp, 165°C heat of combustion, —715.8 kJ/mol( —171.08 kcal/mol) (1) enthalpy of vaporization, 83.89 kJ /mol (20.05 kcal/mol) (2). Some thermodynamic and transport properties of its aqueous solutions have been pubHshed (3), as has the molecular stmcture of the acid as deterrnined by microwave spectroscopy (4). Although first prepared in 1896 (5), its unusual toxicity was not pubhshed until 50 years later (6). The acid is the toxic constituent of a South African plant Dichapetalum i mosum better known as gifirlaar (7). At least 24 other poisonous plant species are known to contain it (8). 

Toxicity. Many /V-nitrosamines are toxic to animals and cells in culture (4,6—8,88). /V-Nitrosodimethy1amine [62-75-9] (NDMA) is known to be acutely toxic to the Hver in humans, and exposure can result in death (89). Liver damage, diffuse bleeding, edema, and inflammation are toxic effects observed in humans as a result of acute and subacute exposure to NDMA. These effects closely resemble those observed in animals dosed with NDMA (89,90). 

Heavy metals on or in vegetation and water have been and continue to be toxic to animals and fish. Arsenic and lead from smelters, molybdenum from steel plants, and mercury from chlorine-caustic plants are major offenders. Poisoning of aquatic life by mercury is relatively new, whereas the toxic effects of the other metals have been largely eliminated by proper control of industrial emissions. Gaseous (and particulate) fluorides have caused injury and damage to a wide variety of animals—domestic and wild—as well as to fish. Accidental effects resulting from insecticides and nerve gas have been reported. 

Ozone is an extremely powerful oxidizing agent, which explains its toxicity to animals and humans. At partial pressures as low as 10 7 atm, it can cut in half the rate of photosynthesis by plants. 

A formidable array of compounds of diverse structure that are toxic to invertebrates or vertebrates or both have been isolated from plants. They are predominately of lipophilic character. Some examples are given in Figure 1.1. Many of the compounds produced by plants known to be toxic to animals are described in Harborne and Baxter (1993) Harborne, Baxter, and Moss (1996) Frohne and Pfander (2006) D Mello, Duffus, and Duffus (1991) and Keeler and Tu (1983). The development of new pesticides using some of these compounds as models has been reviewed by Copping and Menn (2000), and Copping and Duke (2007). Information about the mode of action of some of them are given in Table 1.1, noting cases where human-made pesticides act in a similar way. 

Mechanism of action can be an important factor determining selectivity. In the extreme case, one group of organisms has a site of action that is not present in another group. Thus, most of the insecticides that are neurotoxic have very little phytotoxicity indeed, some of them (e.g., the OPs dimethoate, disyston, and demeton-5 -methyl) are good systemic insecticides. Most herbicides that act upon photosynthesis (e.g., triaz-ines and substituted ureas) have very low toxicity to animals (Table 2.7). The resistance of certain strains of insects to insecticides is due to their possessing a mutant form of the site of action, which is insensitive to the pesticide. Examples include certain strains of housefly with knockdown resistance (mutant form of Na+ channel that is insensitive to DDT and pyrethroids) and strains of several species of insects that are resistant to OPs because they have mutant forms of acetylcholinesterase. These... 

Can cause CNS disturbances Dieldrin is persistent and highly toxic to animals... 

There are, of course, many plants toxic to animals which also may cause dermatitis. Such properties in principle are not necessarily related to allelopathy. 

One of the first considerations in the use of any chemical is possible accumulations of harmful residues in soils. Evidence proves beyond any doubt that many of the newer compounds remain in the soil for at least 5 years. How much longer they may persist, time alone can determine. We know that both selenium and molybdenum can be picked up from soils by plants, which thus become extremely toxic to animals, even when plants themselves are apparently unharmed. Often a given piece of land may be treated safely as far as one crop is concerned but another crop may be injured. For example, potatoes will tolerate large amounts of DDT in the soil as a means of controlling wireworms which are extremely destructive melons, on the other hand, are severely injured by excessive DDT in the soil. There can be no assurance in many cases as to the ultimate use of any... 

Polycationic polymers. These are macromolecules that have electropositive groups attached to the polymer chain or pendant to the chain. These materials are active against a number of bacteria and fungi. However, due to their inherent toxicity to animal species through their destructive interaction with cell membranes they are... 

Percutaneous patches are used in small animals. Fentanyl is a drug used for pain control and is quite effective. Unfortunately, it is quite toxic to animals and young children if accidentally ingested. 

We see from the above that there is a striking alternation in the physiological properties of w-fluorocarboxylic esters of the general formula of F- [CH2]w-C02.R. Thus when n is an odd number the compound is highly toxic to animals, whereas when n is even the compound is non-toxic. All the toxic compounds are powerful convulsant poisons and showed symptoms of the fluoroacetate type. 

Although penicillic acid (59) is produced in high quantities in cultures of Penicillum cyclopium and Penicillum canescens isolated from corn seeds, its toxicity to animals have precluded further development as a herbicidal agent. 

Most, if not all, occupational illnesses associated with 2,4,5-T (such as chloracne) have been found to be the result of product contamination with TCDD. TCDD is extremely toxic to animals, and exposure has also been associated with liver function impairment, peripheral neuropathy, personality changes, porphyria cutanea, hypertrichosis, and hyperpigmentation in humans. TCDD is a chlorinated dioxin, one of a large number of related compounds referred to as dioxins it has no functional use and is not intentionally produced. It has been identified as the responsible toxic agent in several industrial disasters, such as accidental releases at Nitro, WV in 1949, and at Seveso, Italy in 1976. " The role of dioxin contaminants must also be considered in the discussion of 2,4,5-T toxicology. 

Advantages of the carbamate insecticides are lower toxicity to animals and use immediately up to harvest of crops (half-life is one week). Prolonged protection against insects requires frequent sprayings. 

The phenoxy herbicides inexpensiveness, selectivity, nonpersistency and low toxicity to animals are difficult to beat. Application is usually accomplished by spraying on the leaves. The herbicides cannot themselves be applied to the soil because they are washed away or decomposed by microorganisms in a few weeks. They can be applied by this method using a sulfonic acid derivative that, after hydrolysis in the soil and oxidation by bacteria, can form 2,4-D in the plant. 2,4-D is still the main herbicide used on wheat. 

Many other alkaloids are used with various applications. One of them is strychnine, an alkaloid known to be strongly toxic to animals. Drugs such as Dysurgal or Pasuma contain strychnine in clinical doses. Strychnine-containing drugs are used in many disorders, including those of the eye. 

Molybdenum Industrial wastes plants may be toxic to animals None established... 

Protein or calcium deficiency impairs drug metabolism in animals, due to decreased activity of the microsomal enzymes of the liver. The sleeping time by hexobarbitone is increased as a result of prolonged protein malnutrition. Acetylsalicylic acid has been shown to be more toxic to animals on a diet deficient in protein and magnesium. 

The formation of the imidazoles and pyrazines in the ammoniation of molasses17-19 increases the nitrogen content of the molasses, and makes it more valuable as animal fodder, asuthe ammoniated molasses is then a cheap source of protein and not merely a source of energy. Although imidazoles and pyrazines exhibit certain toxicities to animals, these can be overcome.17... 

In Florida late in 1949 King ( 7) found that oil solutions of dieldrin, parathion, lindane, and toxaphene gave excellent control of resistant strains of larvae and that any of these insecticides would be effective substitutes for DDT. However, some of them are very toxic to animal life and must be used cautiously. 

It is used in swine in a single oral administration with feed at a dosage of 7.5-35 mg/kg bw for control of internal and external parasites. Although its anthelminthic spectfum is acceptable in cattle (38) and sheep (39), dichlorvos does not have FDA approval for use in ruminants due to its narrow safety margin. Also, dichlorvos cannot be used in poultry because birds accumulate the resin pellets in their gizzard. Dichlorvos is generally toxic to animals, and it is less toxic via the dermal and oral routes than by parenteral routes. Moreover, dichlorvos is a suspect carcinogen. 

Some of the fluorinated acids are considerably more toxic to animals than to human beings.57 On the other hand, it has been shown that the impact of fluoroacetate-containing plants on fauna results in evolution of a marked tolerance to the poison.58 In the longer chain... 

Ammonia is quite toxic to animal tissues (we examine some possible reasons for this toxicity later), and the levels present in blood are regulated. In many tissues, including the brain, some processes such as nucleotide... 

Ammonia is highly toxic to animal tissues. In the urea cycle, ornithine combines with ammonia, in the form of carbamoyl phosphate, to form citrulline. A second amino group is transferred to citrulline from aspartate to form arginine—the immediate precursor of urea. Arginase catalyzes hydrolysis of arginine to urea and ornithine thus ornithine is regenerated in each turn of the cycle. 

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