Animal uptake

Animal uptake, of herbicides, 23 310 Animal viruses, 3 135-136 Animal waxes, 26 203, 206 Anion binding, in supramolecular chemistry, 24 43-47 Anion-exchange membranes, 15 836 Anion exchangers, organic fouling of, 24 416... 

As mentioned previously and shown in Fig. 6.8, movement of a chemical in a system containing plants or animals may involve exchange with the air, soil, and water phases. Bioaccumulation results when the plant or animal uptakes the contaminant. In plants, the contaminant may be, in turn, released to the air by means of volatilization or to the soil with subsequent accumulation by phytostabilization, adsorption, and sedimentation or transport to the aqueous phase by advective, diffusive, or dispersive processes. Excretion of the contaminant or a metabolite from animals may also be received by any compartment. 

Environmental releases of hazardous waste from contaminated sites can result in transport through several media. The most common pathways include (i) transport through the subsurface to groundwater and (ii) atmospheric transport after release into the air. Other less common pathways after release include surface waters, and plant and animal uptake. 

Even when considered on a long term basis, there is considerable doubt that the presence of land filled battery metals such as lead, zinc, and cadmium would have the catastrophic environmental effects which some have predicted. Studies on 2000-year old Roman artifacts in the United Kingdom (Thornton 1995) have shown that zinc, lead and cadmium diffuse only very short distances in soils, depending on soil type, soil pH and other site-specific factors, even after burial for periods up to 1900 years. Another study in Japan (Oda 1990) examined nickel-cadmium batteries buried in Japanese soils to detect any diffusion of nickel or cadmium from the battery. None has been detected after almost 20 years exposure. Further, it is unclear given the chemical complexation behavior of the metallie ions of many battery metals exactly how they would behave even if metallic ions were released. Some studies have suggested, for example, that both lead and cadmium exhibit a marked tendency to complex in sediments and be unavailable for plant or animal uptake. In addition, plant and animal uptake of metals such as zinc, lead and cadmium has been found to depend very much on the presence of other elements such as iron and on dissolved organic matter (Cook and Morrow 1995). Until these behavior are better understood, it is unjustified to equate the mere presence of a hazardous material in a battery with the true risk associated with that battery. Unfortunately, this is exactly the method which has been too often adopted in comparison of battery systems, so that the true risks remain largely obscured. 

A very large amount of information is available on the levels of total copper in various compartments of the environment, but little information on copper speciation (WHO 1998). Copper is transformed in the environment to forms that are either more or less bioavailable, depending upon the physical and chemical conditions present in the environment of interest. The net uptake of copper by microorganisms, plants, and animals from the surrounding environment (water, sediment, soil, and diet) is defined as bioaccumulation . The species of copper present in environmental media and its associated bioavailability, together with differences in plant and animal uptake and excretion rates, determine the extent of bioaccumulation. 

Antimicrobial Activity. The elfamycins antimicrobial specificity and lack of toxicity in animals can be explained in view of species-dependent specificity of elfamycin binding to EE-Tu. Inefficient cellular uptake or the presence of a nonresponding EE-Tu were cited as responsible factors for the natural resistance in Halohacterium cutiruhrum (67), Lactobaci//us brevis (68), and in actinomycetes (5,69). The low activity of elfamycins against S. aureus was also attributed to an elfamycin-resistant EE-Tu system (70). However, cross-resistance with other antibacterial agents has not been observed (71). 

Agricultural Use. Citric acid and its ammonium salts are used to form soluble chelates of iron, copper, magnesium, manganese, and zinc micronutrients in Hquid fertilizers (97—103). Citric acid and citrate salts are used in animal feeds to form soluble, easily digestible chelates of essential metal nutrients, enhance feed flavor to increase food uptake, control gastric pH and improve feed efficiency. 

Agriculture ndNutrition. Cobalt salts, soluble in water or stomach acid, are added to soils and animal feeds to correct cobalt deficiencies. In soil apphcation the cobalt is readily assimilated into the plants and subsequendy made available to the animals (56). Plants do not seem to be affected by the cobalt uptake from the soil. Cobalt salts are also added to salt blocks or pellets (see Feeds and feed additives). 

Organoselenium compounds in particular, once ingested, are slowly released over prolonged periods and result in foul-smelling breath and perspiration. The element is also highly toxic towards grazing sheep, cattle and other animals, and, at concentrations above about 5 ppm, causes severe disorders. Despite this, Se was found (in 1957) to play an essential dietary role in animals and also in humans — it is required in the formation of the enzyme glutathione peroxidase which is involved in fat metabolism. It has also been found that the Incidence of kwashiorkor (severe protein malnutrition) in children is associated with inadequate uptake of Se, and it may well be involved in protection... 

Alzheimer s disease (AD) 2. In the hippocampus of p-amylo id-treated rats, an animal model of AD, 2-AG levels are elevated and exert neuroprotection but also participate in memory retention loss 2. Inhibitors of cellular re-uptake or CB-, antagonists, possibly depending on the phase of the disorder... 

Multiple sclerosis (MS) 4. In rats with EAE, an animal model of multiple sclerosis, AEA and 2-AG levels are decreased in the striatum and midbrain. This might be associated with motor impairment 4. Inhibitors of degradation (both FAAH and cellular re-uptake)... 

Neuronal excitotoxicity AEA levels are elevated in the hippocampus of mice treated with kainic acid. 2-AG levels are elevated in rats treated with pilocarpine These are two animal models of epileptic seizures, where the endocannabinoids play an anti-convulsant and protective function Inhibitors of cellular re-uptake... 

Knockout mice have been reported for several FATPs [1]. As insulin desensitization has been closely linked to excessive fatty acid uptake and intracellular diacylgly-cerol and TG accumulation, these animal models were particularly evaluated in the context of protection from diet-induced type 2 diabetes ( Type 2 Diabetes Mellitus (T2DM)). In addition, studies on human subjects have also established genetic links between polymorphisms in FATP genes and metabolic alterations [1]. 

The major routes of uptake of xenobiotics by animals and plants are discussed in Chapter 4, Section 4.1. With animals, there is an important distinction between terrestrial species, on the one hand, and aquatic invertebrates and fish on the other. The latter readily absorb many xenobiotics directly from ambient water or sediment across permeable respiratory surfaces (e.g., gills). Some amphibia (e.g., frogs) readily absorb such compounds across permeable skin. By contrast, many aquatic vertebrates, such as whales and seabirds, absorb little by this route. In lung-breathing organisms, direct absorption from water across exposed respiratory membranes is not an important route of uptake. 

After uptake, lipophilic pollutants tend to move into hydrophobic domains within animals or plants (membranes, lipoproteins, depot fat, etc.), unless they are biotransformed into more polar and water soluble with compounds having low Metabolism of lipophilic compounds proceeds in two stages ... 

Hansen, D.J., Parrish, P.R., and Forester, J. (1974). Aroclor 1016-Toxicity to and Uptake hy Estuarine Animals. Environmental Research 7, 363-373. 

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