Organic lead absorption

Rosen JF, Chesney RW, Hamstra AJ, et al. 1981. Reduction in 1,25-dihydroxyvitamin D in children with increased lead absorption. In Brown SS, Davis DS, eds. Organ-directed toxicity Chemical indices and mechanisms. New York, NY Pergamon Press, 91-95. 

Reisinger et al. [21] used the gas chromatographic-atomic absorption spectrometric technique to demonstrate that biomethylation of inorganic lead does not account for the presence of organolead compounds in sediments. Sulphide induced chemical conversion of organic lead(IV) salts into alkyl lead compounds is, however, possible. 

Lead compounds. These are powerful cumulative poisons and ingestion of even small amounts must be guarded against. Organic lead compounds (e.g. lead tetra-ethyl) are volatile and inhalation of their vapours must be avoided they are also dangerous by skin absorption. 

Procedure Use an atomic absorption spectrophotometer equipped with a 4-in., single-slot burner head. Set the instrument to previously determined optimum conditions for organic solvent aspiration (3 to 5 mL/min) and at a wavelength of 283.3 nm Use an air-acetylene flame adjusted for maximum lead absorption with a fuel-lean flame. Aspirate the blanks, the Standard Solutions, and the Sample Solution, flushing with water and then with Aqueous Butyl Acetate between... 

Gastrointestinal absorption, and subsequent utilization and retention by the body, of essential trace elements such as zinc, copper, and selenium can also be enhanced or diminished by the presence or absence of other trace elements and chemicals in the diet (WHO, 1996). For example, cadmium and lead absorption is enhanced when dietetic intake of calcium, iron, and phosphate is low. Phytate, an organic phosphate that is abundant in diets high in unrefined grains, especially when accompanied by high dietetic calcium, helps suppress the uptake of potentially toxic elements such as lead and cadmium, but also inhibits the uptake of essential zinc (WHO, 1996). 

Inhalation. Ready absorption of lead-rich fumes, volatile organic lead compounds, or soluble lead-rich particles. 

CaCO ) and for bluegill sunfish 23.8 pg 1 Pb (hardness = 20 mg 1 ) [7] Man can also be threatened by lead-contaminated water, seafoods or fresh-water fish. After absorption in the organism, lead is transported by the blood to the soft tissues, the highest concentrations being found in the liver and kidneys. Some, however, is transported to other organs such as the brain, lung, spleen and heart. Deposition of lead takes place in bone (where more than 90 per cent of the total body lead is found) as... 

A. Dermal absorption is minimal with inorganic lead, but may be substantial with organic lead compounds, which may also cause skin irritation. 

Electronic properties of semiconductor ensembles have been examined by absorption spectroscopy [770]. Interparticle interactions could lead to a discernable change in the optical properties of a lattice of semiconductor nanocrystals. The couphng of the electronic states could vary from weak to strong. Absorption spectra showing the results of weak coupling in CdSe nanocrystals are shown in Fig. 4.19. When present in close-packed organization, the absorption spectra of the nanocrystals are broadened and red-shifted. 

A useful indicator of excessive lead effect is the presence of free erythrocytic porphyrin (FEP). It can be measured from a small quantity of blood obtained by finger-prick. For confirmatory evidence of excessive lead absorption or poisoning, urine estimation of coproporphyrin and amino laevulinic acid are helpful. Inorganic lead is best monitored by blood sampling and organic lead by urine sampling. 

It has been noted (Section 5.1.2.3) that production of tetraalkyllead compounds gives rise to effluent streams contaminated with gaseous organic lead compounds. These cannot be controlled by the application of particulate control technology, and considerable effort has been expended in recent years to achieve satisfactory control. Present practice in England involves the use of an activated carbon absorption plant, followed by recovery of absorbed lead by steam stripping [7]. 

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