Uptake and Distribution

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. 

An important factor in determining the course of uptake, transport, and distribution of xenobiotics is their polarity. Compounds of low polarity tend to be lipophilic and of low water solubility. Compounds of high polarity tend to be hydrophilic and of low fat solubility. The balance between the lipophilicity and hydrophilicity of any compound is indicated by its octanol-water partition coefficient (K J, a value determined when equilibrium is reached between the two adjoining phases  

Compounds with high values are of low polarity and are described as being lipophilic and hydrophobic. Compounds with high values are of high polarity and are hydrophilic. Although the partition coefficient between octanol and water is 

Organic Pollutants An Ecotoxicological Perspective, Second Edition 

Before leaving the subject of polarity and in relation to uptake and distribution, mention should be made of weak acids and bases. The complicating factor here is that they exist in solution in different forms, the balance between which is dependent on pH. The different forms have different polarities, and thus different values. In other words, the values measured are pH-dependent. Take, for example, the plant growth regulator herbicide 2,4-D. This is often formulated as the sodium or potassium salt, which has high water solubility. When dissolved in water, however, the following equilibrium is established  

Acutely toxic amounts of metals and their compounds are usually taken in through the mouth or lungs. In addition to the dose, the method of uptake determines the intensity as well as the duration of toxic effects, and can lead to very different symptoms (see the above-mentioned example of ingested metallic mercury and inhaled mercury vapor). 

Oral uptake often results in vomiting, which reduces the amount of toxin that can be absorbed. Metal compounds can react with either the acid in the stomach or the alkaline environment of the intestine, and this can decidedly influence solubility. Before being distributed throughout the body, the metals pass through the liver, where often detoxification processes begin. The inhalation of fine particles can result in a direct and rapid transfer of soluble metal compounds into the blood, leading to a rapid transfer and onset of symptoms. Toxic quantities of metals can also be absorbed through mucous membranes. Cuta- 

---

Collier P.J., Ramsey A.J., Austin P. Gilbert P. (1991) Uptake and distribution of some isothiazolone... 

Astrand I, Ovrum P. 1976. Exposure to trichlorethylene. I. Uptake and distribution in man. Scan J Work Environ Health 4 199-211. 

Schreckhise RG, Cline JF. 1980. Comparative uptake and distribution of plutonium, americium, curium and neptunium in four plant species. Health Phys 38 817-824. 

Most trace metals may be precipitated with phosphate into insoluble metal phosphates (Table 7.5). Most metal phosphates have low solubility. High localization of phosphates reduces the bioavailability of Zn in arid soils. The banded application of P near the seeds depresses Zn uptake by com (Adriano and Murphy, 1970 Grant and Bailey, 1993), causing Zn deficiency. However, both N and P fertilizers increase Cd concentration in plants. Cadmium and Zn are antagonistic in root uptake and distribution within plants. 

Jiao Y., Bailey L.D., Grant C.A. Effects of phosphorus and zinc fertilizer on cadmium uptake and distribution in flax and durum wheat. J Sci Food Agri 2004 84 777-785. 

Myttenaere, C., Verfaillie, G. and Bordeau, P. (1967). Uptake and distribution of 144-Ce in Oryza Sativa, page 437 in Radioecological Concentration Processes, Aberg, B. and Hungate, F. P., Eds. (Pergamon Press, London). 

Hemelraad, J., H.A. Kleinveld, A.M. de Roos, D.A. Holwerda, and D.I. Zandee. 1987. Cadmium kinetics in freshwater clams. III. Effects of zinc on uptake and distribution of cadmium in Anodonta cygnea. Arch. Environ. Contam. Toxicol. 16 95-101. 

Gunkel, G. 1981. Bioaccumulation of a herbicide (atrazine, s-triazine) in the whitefish (Coregonus fera J.) uptake and distribution of the residue in fish. Arch. Hydmbiol. Suppl. 59(2/3) 252-287. 

Modified from Turner, B.C. and J.H. Caro. 1973. Uptake and distribution of carbofuran and its metabolites in field-grown corn plants. Jour. Environ. Qual. 2 245-247. 

Balk, L., J. Meijer, J.W. DePierre, and L.E. Appelgren. 1984. The uptake and distribution of (3H) benzo[a]pyrene in the northern pike (Esox lucius). Examination by whole-body autoradiography and scintillation counting. Toxicol. Appl. Pharmacol. 74 430-449. 

Gillespie, R.B., P.C. Baumann, and C.T. Singley. 1988. Dietary exposure of bluegills (Lepomis macrochirus) to (75)Se uptake and distribution in organs and tissues. Bull. Environ. Contamin. Toxicol. 40 771-778. 

Walker SJ, Llewellyn GC, Lillehoj EB, Dashek WV. Uptake and distribution of aflatoxin Bj in excised, soybean roots and toxin effects on root elongation. JEnviron ExperBot 1984 24 113-122. 

De La Cruz AA, Rajanna B. 1975. Mirex incorporation in the environment uptake and distribution in cropseedlings. Bull Environ Contam Toxicol 14(1) 38-42. 

The uptake and distribution of organochlorine insecticides has been studied under a variety of conditions. Although the results indicate that further study is needed on a characterization of extraneous factors that affect disposition, the studies clearly demonstrate the presence of a membrane barrier to insecticide penetration in the R population. This membrane barrier would aid in the protection of target sites in the R fish from the insecticide. This barrier is felt to be an important factor in resistance to organochlorine insecticides in mosquitofish. 

The fluorescent labels reported for investigation of intracellular uptake and distribution by CLSM comprise Nile red [13], Texas Red, and 6-coumarin [14]. Not only for fluorescence microscopy but also for transmission electron microscopy (TEM), the loading of markers proved to be useful. Osmium tetroxid as an electron dense marker and bovine serum albumin (BSA) as a model protein were entrapped in PLGA-nanoparticles to elucidate their uptake and intracellular distribution in human vascular smooth muscle cells [15]. 

Smolders, E., and Shaw, G., 1995,. Changes in radiocaesium uptake and distribution in wheat during plant development a solution culture study. Plant Soil 176 1-6. 

Rowell PP, Hurst HE, Marlowe C, Bennett BD (1983) Oral administration of nicotine its uptake and distribution after chronic administration to mice. J Pharmacol Methods 9 249-261 Russell MAH (1990) Nicotine intake and its control over smoking. In Wonnacott S, Russell MAH, Stolerman IP (eds) Nicotine psychopharmacology, molecular, cellular and behavioural aspects. Oxford University Press, New York, pp 374 18... 

McFarlane JC, Pfieeger T, Fletcher J. 1987b. Transpiration effect on the uptake and distribution of bromacil, nitrobenzene, and phenol in soybean plants. J Environ Qual 16 372-376. 

Gerlach, T., Biesalski, H. K., Weiser, H., Haeussermann, B., and Baessler, K. H. (1989). Vitamin A in parenteral nutrition Uptake and distribution of retinyl esters after intravenous application. Am. ]. Clin. Nutr. 50,1029-1038. 

---